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WO2024108310A1 - Environmentally friendly hemp plastic composite formulations and molding methods - Google Patents

Environmentally friendly hemp plastic composite formulations and molding methods Download PDF

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Publication number
WO2024108310A1
WO2024108310A1 PCT/CA2023/051579 CA2023051579W WO2024108310A1 WO 2024108310 A1 WO2024108310 A1 WO 2024108310A1 CA 2023051579 W CA2023051579 W CA 2023051579W WO 2024108310 A1 WO2024108310 A1 WO 2024108310A1
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WO
WIPO (PCT)
Prior art keywords
hemp
particles
plastic composite
hurd
control system
Prior art date
Application number
PCT/CA2023/051579
Other languages
French (fr)
Inventor
Leonardo SIMON
Douglas CASETTA
Franciele TURBIANI
Original Assignee
Tangho Green Canada Inc.
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Filing date
Publication date
Application filed by Tangho Green Canada Inc. filed Critical Tangho Green Canada Inc.
Publication of WO2024108310A1 publication Critical patent/WO2024108310A1/en

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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C08J5/045Reinforcing macromolecular compounds with loose or coherent fibrous material with vegetable or animal fibrous material
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C08J5/06Reinforcing macromolecular compounds with loose or coherent fibrous material using pretreated fibrous materials
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2499/00Characterised by the use of natural macromolecular compounds or of derivatives thereof not provided for in groups C08J2401/00 - C08J2407/00 or C08J2489/00 - C08J2497/00

Definitions

  • the present disclosure relates to hemp fiber, and novel formulations and processes for the manufacture of plastic composites incorporating hemp fiber, and molding methods for making useful articles therefrom.
  • Plastics and resins are very versatile because they enable a wide variety of useful articles to be made to meet many applications. This demand for plastic molded products can be found in housing, transportation, packaging, health care, energy, nutrition, communications, and many other sectors. In housing for example, furniture, flooring, windows and doors, and fixtures can be manufactured by injection molding, compression molding or extrusion. In transportation, parts for vehicles can be molded from plastics to the exact shapes required to enable functionality and safe operation of vehicles.
  • plastics and resins are made with petroleum feedstock, which is non-renewable, or do not biodegrade.
  • the negative environmental impacts of such non-renewable plastic waste are well known, including widespread pollution in lakes, seas and oceans, injuries to wildlife, and contribution to air pollution when plastic waste is incinerated. Recycling plastics has an environmental appeal because recycling turns the waste plastic into a useful product, thus eliminating the disposal of plastic waste in landfill, and preventing plastic waste from polluting the oceans.
  • the present disclosure relates to hemp fiber, and novel formulations and processes for the manufacture of plastic composites incorporating hemp fiber, and molding methods for making useful articles therefrom.
  • a method of producing a mouldable hemp plastic composite comprising: i) sourcing hemp hurd; ii) processing the hemp hurd utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired freeness measurement; and iii) formulating a hemp plastic composite comprising a combination of hemp particles processed in step ii) with one or more thermoplastics.
  • the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
  • CSF Canadian standard freeness
  • the hemp hurd is sourced from a Cannabis sativa plant.
  • the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
  • the method further comprises processing a mixture of hemp particles and one or more thermoplastics between 100 °C to 230 °C.
  • the method further comprises: a) identifying a use case for a molded product; and b) formulating the plastic composite comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product.
  • the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
  • the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, dimensional conformity, and thermal, chemical, and electrical properties.
  • the process control system receives feedback from test measurements comprising one or more of tensile testing, flexural testing, impact testing, hardness testing, density measurement, melt flow index, thermal analysis, chemical resistance, environmental testing, dimensional measurements, flammability testing, and electrical properties testing.
  • the system incorporates an artificial intelligence (Al) / machine learning (ML) engine which may be trained on feedback from the test measurements to determine which hemp plastic composite formulations result in the desirable properties for one or more use cases.
  • Al artificial intelligence
  • ML machine learning
  • the AI/ML engine is adapted to recommend a hemp plastic composite formulation for a given use case.
  • the AI/ML engine is further adapted to control the proportion of hemp particles to one or more thermoplastics.
  • the AI/ML engine is further adapted to control the proportion of hemp particles, one or more thermoplastics, and one or more additives to achieve desirable properties for one or more use cases.
  • the AI/ML engine is further adapted to recommend control settings for the mixing process, the mixing temperature, and the subsequent moulding process.
  • a mouldable hemp plastic composite formulation comprising: a) hemp particles sourced from the hemp hurd, the hemp particles having a desired freeness measurement; and b) one or more thermoplastics.
  • the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml. In another embodiment, the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
  • CSF Canadian standard freeness
  • the mouldable hemp plastic composite formulation further comprises one or more additives to achieve desirable properties for one or more use cases.
  • the hemp hurd is sourced from a Cannabis sativa plant.
  • FIGS. 1A - 1C show a schematic overview of processes in accordance with illustrative embodiments.
  • FIG. 2 shows an illustrative bar graph of size distributions of hemp Hurd fiber as measured by the opening in micrometers in accordance with an illustrative embodiment.
  • FIG. 3 shows an illustrative bar graph of size distributions of Tornado Pulper (TP) fiber as measured by the opening in micrometers in accordance with another illustrative embodiment.
  • TP Tornado Pulper
  • FIG. 4A shows an illustrative bar graph of size distributions of Twin Flow Refiner (TFR) fiber as measured by the opening in micrometers in accordance with another illustrative embodiment.
  • TFR Twin Flow Refiner
  • FIG. 4B shows an illustrative bar graph of size distributions of Atmospheric Refiner (ATM) fiber as measured by the opening in micrometers in accordance with another illustrative embodiment.
  • FIG. 4C shows an illustrative line graph of size distributions of Hurd, TP, and TFR samples in accordance with an illustrative embodiment.
  • ATM Atmospheric Refiner
  • FIG. 4D shows an illustrative process for utilizing an Al / ML engine to iteratively improve the hemp plastic composite formulation and a corresponding moulding process.
  • FIGS. 5A - 5C show an illustrative bar graph of a comparison of the flexural modulus of different samples of materials used in testing in accordance with an illustrative embodiment.
  • FIG. 6 shows a schematic block diagram of a generic computer system which may provide an operating environment for one or more embodiments.
  • the present disclosure relates to hemp fiber, novel formulations and processes for the manufacture of plastic composites incorporating hemp fiber, and molding methods for making useful articles therefrom.
  • Natural fibers are renewable, recyclable and have low specific gravity when compared to minerals, such as talc or calcium carbonate, or compared to glass fibers.
  • minerals such as talc or calcium carbonate
  • other natural fibers that have been explored to decrease the environmental impact of plastic composites include, wood fiber, jute, sisal, coconut, and straw for example.
  • Industrial hemp has a growing and harvesting cycle that is much shorter than trees, which enables the production of more biomass per hectare per year.
  • Industrial hemp can be used to produce long fibers with applications in ropes and twines, textiles, and non-woven fiber products.
  • Long fibers can be removed from industrial hemp main stock using a process of decortication to produce clean fibers with lengths longer than 10 cm .
  • the stalk of industrial hemp can yield long fibers in the range of about 10-20 wt.%.
  • FIG. 1A illustrates steps for production of hemp fiber in accordance with an embodiment.
  • Industrial hemp crop is a plant that has a relatively thin stalk that can be mechanically or manually harvested. The hemp leaves and grains can be separated from the stalk during harvesting.
  • the hemp stalk can then be submitted to a process known as decortication.
  • This process mechanically separated the bast fiber and hurd, and a certain amount of dust is produced as a by-product.
  • the materials produced during the decortication process are bast and hurd fiber.
  • a mechanical method is used for separating bast fiber and hurd fiber using the hemp stalk as a feedstock. This method is described in further detail below.
  • the remainder of the material produced during the decortication process is composed of fine dust and hurd.
  • Fine dust has atypical particle size smaller than 2 mm.
  • Hurd is produced as a by-product of decortication to be 50 wt.% or more, depending on type of industrial hemp and decortication process.
  • Hurd produced during the decortication process generally has a size larger than 2 mm, and smaller than 10 cm.
  • hurd is rich in cellulose, it is often considered a waste product produced during the production of long bast fibers from industrial hemp. While hurd has been used to produce energy pellets or sorbent materials, other uses for hurd are not common.
  • Fibers rich in cellulose can be produced by chemical or mechanical methods using processes known as pulping. Chemical pulping produces cellulose fibers of high quality by chemically removing lignin, but the process requires utilization of chemicals. Cellulose is separated from lignin in the chemical pulping process. Immediately after separation from cellulose, lignin is mixed with chemicals. The reparation of the lignin from chemicals after chemical pulping requires further processing to recover the chemicals.
  • Mechanical pulping produces cellulose fibers without the use of chemicals. Special equipment is used to separate fibers using physical forces.
  • One type of equipment used in mechanical pulping is a refiner.
  • the mechanical pulping process is cleaner than chemical pulping because it does not require handling chemicals and it does not produce any chemical waste that would require further processing.
  • the fibers produced by mechanical pulping contain cellulose and lignin.
  • the refiner uses mechanical stresses to produce cellulose fibers containing lignin.
  • One advantage of the mechanical pulping method is the absence of chemicals or by-products.
  • the invention presented here is described by a mechanical method to process hemp bast fiber, hurd or hemp stalk to generate hemp fiber without the use of chemical.
  • the main aspect of the production of hemp fiber is the utilization of mechanical equipment knows as refiners.
  • the hemp feedstock composed of bast fiber, hurd or simply hemp stalk, is fed into and equipment known as tornado pulper. Then the material is further processed with other types of refiners to further reduce the diameter of the fibers. Water is also utilized in this process. Typical types of refiners are tornado pulper, atmospheric refiner, twin flow refiner, or Masuko refiner.
  • FIG. IB shows the flow diagram for the process utilizing hemp hurd fiber as a feedstock and mechanical methods including a tornado pulper, screw press, atmospheric refiner, twin flow refiner and Masuko refiner.
  • the role of the refiners is to reduce fiber diameter while increasing its quality.
  • the role of the screw press is to adjust the amount of water required in the process.
  • Plastics are often mixed with other ingredients when manufacturing composite products. Fillers or fibers can be added to the formulation of plastic composites to control properties and other attributes. Mineral fillers such as talc, mica or calcium carbonate are typically added to increase rigidity of the final product. Glass fiber can be added to the formulation of plastics to increase rigidity and strength. Short glass fiber has a length typically smaller than 10 mm . When the plastics containing glass fiber are pelletized, the length of glass fiber is the same or smaller than the pellet. Plastic pellets often have 3 to 4 mm in diameter and 2 to 10 mm in length, although other sizes are also possible.
  • Cellulose fibers sourced from forestry or agriculture have been used as filler or reinforcing agents in plastics as well. These cellulose fibers can be prepared by gridding, milling, or pulping. The type of process selected for manufacturing fibers is responsible for determining their characteristics like length and aspect ratio of the cellulose fibers. These characteristics of the cellulose fibers can affect rigidity, strength, and other properties of the final plastic composites, such as impact resistance, wear resistance, deformability, and insulation properties.
  • a sustainable hemp plastic composite product and a process for its preparation is disclosed in which industrial hemp is carefully selected and processed with specific mechanical methods and then combined preferably with recycled plastics or biodegradable plastics.
  • the product and process address a need for mouldable thermoplastics with a low environmental footprint.
  • Fibers produced from industrial hemp are renewable.
  • a mechanical refining process is employed to produce cellulose fibers and particles using industrial hemp hurd.
  • the fibres and particles produced from hurd feedstock herein can improve the mechanical properties of plastics.
  • the mechanical stiffness and strength of these composites containing cellulose fibers produced from industrial hemp hurd are superior to the properties of the same thermoplastics without these added materials.
  • These hemp plastic composites also have a lower environmental footprint because their components are mainly either renewable, or recycled or biodegradable, and provide a unique pathway for producing mouldable thermoplastic composites from an environmental perspective.
  • FIG. 1C shows the flow diagram for the process necessary for manufacturing mouldable thermoplastics composites.
  • the process starts by selecting a grade of fiber obtained from processing hemp with refiners. These fibers are obtained in water; hence a dryer is utilized to decrease the moisture content below 5 wt.%.
  • the dried fibers are mixed with polymer and additives to exact quantities to achieve a desirable formulation.
  • the mixture is then fed into equipment to mix all ingredients in the formulation while melting the thermoplastic polymer using heat.
  • the product is cooled down to room temperature and cut into pellets.
  • the pellets contain a homogenous mixture of all ingredients including the hemp fiber.
  • the pellets are stable and can be stored for a long time when needed. The moisture level in pellets can increase during storage.
  • the pellets can be dried prior to injection molding to achieve a moisture level below 2 wt.%.
  • the dried pellets are then fed into an injection molding machine equipped with a mold to manufacture the final product consisting of a recycled or biodegradable plastics, additives, and hemp fibers.
  • Different grades of thermoplastics, additives, and hemp fiber can be combined during the above- mentioned process to achieve a balance of optimal performance while decreasing the environmental footprint.
  • the resulting hemp plastic composite product is suitable for manufacturing a wide range of mouldable parts useful for transportation, furniture, packaging, and other industrial applications that can benefit from a material and a process with low environmental impact. Illustrative embodiments will be described below with reference to tables and figures.
  • FIGS. 1A - 1C a schematic overview of aprocess according to an illustrative embodiment is shown.
  • the stages of the process are as follows:
  • the selection of the hurd is relevant because it determines the particle size, morphology, and the chemical composition of the hemp hurd used in a composite material. Characteristics of the chemical composition of the hemp hurd may include the quantities of cellulose, hemicellulose, lignin, moisture, and various other components.
  • the morphology of the plant tissue is very relevant, including the arrangement and geometry of cells, determining the orientation of the cell and fibers within the plant tissue. These attributes affect the composition because they will determine thermal properties, strength, and crystallinity of the finished molded product. Hemp plants contain different parts: roots, stalk, leaves, flower, and seeds.
  • a hemp plastic composite formulation uses a part of the stalks, more specifically the hemp hurds.
  • Hemp hurds are the woody inner parts of the hemp stalk and can be broken into fragments and separated from the long fiber by breaking and scutching them. The outcome of this process is the separation of three main fractions: long fibers, hurd and dust. Hurd is selected for this technology due to its characteristics, abundance, and size.
  • the particle size of hemp hurd from decortication is commonly between 0.5 cm and 10 cm, with elongated shape.
  • the competitive advantage of proper selection of feedstock resides in its high yield after the decortication process, the absence of dust and other impurities (leaves and flowers), the amount of crystallinity and thermal stability.
  • FIG. 2 shows an illustrative size distribution of hemp hurd fiber in accordance with an embodiment.
  • the hurd selected in stage 1 as described above is the feedstock for the processing with mechanical refiners.
  • the process is based on rotating discs that can decrease the particle size of hurd while producing particles with high aspect ratio due to shearing forces produces between the two discs and feedstock. This is fundamentally different than decreasing particle size of hurd by hammer milling or ball milling, as may be used in the prior art.
  • the hurds are first processed on an equipment known as tornado pulper in high dilution to decrease the particle size to less than 2 cm, and the output of the tornado pulper is fed in high dilution into a disc refiner to further decrease the particle size while maintaining the aspect ratio.
  • the dilution is a dispersion of hemp in water measured as consistency.
  • the particle produced after processing through the disc refiner can have the appearance of fibers or plates, accompanied by a somewhat small number of fine particles with low aspect ratio.
  • the combination of such particle shapes, sizes and aspect ratios is unique to the combination of processes utilized in its manufacture.
  • the materials produced in this process is rich in hemp fiber.
  • the diameter of the particles produced by the disc refiners is less than 0.5 cm, or better yet, less than 0. 1 cm, or even less than 0.05 cm.
  • the aspect ratio of fiber may be measure by optical microscopy resulting in a distribution of values between approximately 1 and 30.
  • FIG. 3 shows an illustrative size distribution of tornado pulper fiber in accordance with an embodiment.
  • the reduction of size and the increase in aspect ratio result in an increase in surface area for a given mass amount of product.
  • the resulting increase in surface area can create porosity with capacity to retain water due to capillary forces.
  • Table 1 Canadian standard freeness from hemp h rd refining, the resulting material can retain water as measured by the Canadian Standard Freeness values between 583 and 157.
  • hemp materials containing fibers, small particles, high aspect ratio and high surface area is highly desirable for application in composites because of its capacity to transfer and carry mechanical loading in composites with thermoplastics.
  • thermoplastics A competitive advantage for products manufactured with thermoplastics is related to its reduced environmental footprint. This is particularly relevant with respect to packaging, consumer goods and other markets that require products with a relatively short lifetime. Examples in this category are packaging for consumer goods. This is fundamentally different than plastics used for building infrastructure with expected long lifetime - one example of this is plastic for water pipes.
  • a key factor of the hemp plastic composite technology developed here is the selection of recycled thermoplastic or compostable thermoplastic.
  • Recycled polypropylene is a resin that has reduced environmental footprint because it does not require using new petroleum feedstock and avoids plastic scrap going to landfills.
  • PBAT is a compostable thermoplastic, its utilization is advantageous when the product is contaminated and does not lend itself for recycling.
  • PBS is a biodegradable synthetic polymer that is often used to create environmentally friendly and sustainable materials.
  • Hemp particles as described herein are preferably produced from hemp h rd processed by disc refiners.
  • the utilization of disc refiners allows a desirable particle size to be achieved and is believed to be a unique characteristic of the present hemp plastic composite technology.
  • disc refiners are especially well suited as it modifies the properties of hemp fibers mechanically.
  • Similar technologies utilizing disk and conical geometries which operate in the same way may also be used. Generally, such technologies may use a disk with cutting blades on the rotating surface, and a stationary disk also with blades. The blade design is a determining factor for refiner efficiency.
  • the raw material and type of fiber treatment are considered to calculate the appropriate blade design.
  • the desired fiber treatment is promoted.
  • the design of the blades is made according to the desired treatment, which can be high fibrillation, cutting or some combination of these.
  • the fibers dispersed or diluted in water then pass between the discs and receive the required treatment.
  • the high aspect ratio of fibers is among the most important properties making this material a good reinforcement filler. Avoiding fiber breakage during the dispersion process is essential to achieve superior enforcement.
  • hemp hurd is a renewable material which contributes to further decreasing the environmental footprint of thermoplastics.
  • composition of the matter is relevant because it controls the environmental footprint and the performance of the product.
  • formulations relevant to the technology developed here makes of at least 80 % containing ingredients with reduced environmental footprint and no more than 20 % of other ingredients with the objective to further increase other properties.
  • these other ingredients can be used, but are not limited to, improving thermal stability, flow of plastic during molding, strength of plastic goods and appearance.
  • the help plastic composite technology used here makes use of extruder (e.g., a twin-screw extruder) or other polymer mixing equipment can be used to melt the thermoplastics and mixing all ingredients.
  • the equipment can be continuous or batch.
  • melting and mixing may be achieved using a twin-screw extruder producing a pellet of thermoplastic, hemp, and additives.
  • the feedstock of hemp particles produced in stage 1 as described above have sufficient thermal stability to avoid thermal degradation when processed with compounding extrusion to temperatures up to 230°C.
  • This hemp feedstock may be prepared with a particular particle size and shape to ensure that its loading into the extrusion equipment is feasible, and it does not increase the viscosity of the molten plastic mixture to exceed the extrusion equipment capacity. After melting and mixing thermoplastics, hemp feedstock, and additives, the material is pelletized.
  • additives include compatibilizer, waxes, and lubricants.
  • compatibilizer that works between the hemp fibers and the polymer increases adhesion between the two materials, and consequently result in improved mechanical properties with stiffness and strength.
  • To create a strong composite there must be good adhesion between the polymers and fibers. To achieve this, they need to come in close contact, have appropriate surface tensions and, in most cases, have the same chemical polarity.
  • Weak adhesion is one of the biggest difficulties along with breakage and alteration of morphology between natural fibers in the polymer. This can be because natural fibers have low thermal stability, and high susceptibility to moisture as well as they experience fiber decomposition during compounding. Some other factors that affect bonding that should be considered are atomic arrangement, chemical properties, molecular conformations, and chemical constitution.
  • Fiber dispersion is also an important factor to consider in the performance of composites as well using some waxes and lubricants, or other additives, to improve fiber dispersion and reduce hydrogen bonding.
  • the pellets produced in stage 5 as described above are suitable for processing with conventional molding processes found the plastics manufacturing industry.
  • the pellets present adequate flow behavior to enable processability by compression molding or injection molding in cycle times shorter than preferably 1 minute. This is due to the selection of the formulation and material characteristics as described above. More specifically, the particles of hemp produced in stage 2 as described above have adequate size, shape, and aspect ratio to have a minimal effect on the flow properties of the compounded formulation.
  • short hemp fibers can be carried out in different percentages, normally between about 5% and 30% by weight, but also reaching 50% of the weight of the final material.
  • This amount of short hemp fiber selected should occur according to the particular industrial applications (automotive, construction materials, external applications, etc.) of the composites and their destination (i.e., environmental conditions such as temperature and humidity, and exposure to sunlight). For example, in the automotive industry, different percentages may be used for indoor and outdoor applications in automobiles. 7, Measurement of performance of molded parts (mechanical properties)
  • thermoplastics with physical properties that are improved in comparison to the properties of the thermoplastics used to make such composites.
  • the flexural strength of PBAT is 4 MPa and the thermoplastic composite of PBAT with 20% hemp processed by the atmospheric refiner is 16 MPa. This represents an increase of 400% in the physical property.
  • Table 5 shows illustrative tensile properties of hemp fiber filled PBAT composites.
  • Table 6 illustrates the results of flexural properties and Izod impact strength using polybutylene succinate (PBS) without hemp fibers and with hemp fibers acquired at various stages and mechanical refiners as an example.
  • PBS polybutylene succinate
  • Table 7 depicts the tensile properties of hemp fiber filled PBS composites.
  • the performance of molded parts is tested for various performance measurements (e.g., elasticity or stiffness, hardness, fracture resistance, flexural strength, fatigue strength, tensile strength, wear strength, thermal properties, etc.) and feedback from the testing is utilized as an input to further improve the formulation of the composite for particular use cases.
  • various performance measurements e.g., elasticity or stiffness, hardness, fracture resistance, flexural strength, fatigue strength, tensile strength, wear strength, thermal properties, etc.
  • the composites fdled with the developed hemp fibers showed promising results in relation to their mechanical properties, enhancing their applications in injection molded parts for the automotive and furniture industries.
  • the addition of 20% hemp fiber increased the tensile modulus of the composites as well as their flexural modulus.
  • the increase was up to 140 % in the recycled polypropylene, 190 % in the polybutylene succinate, and 778% in the polybutylene adipate terephthalate when compared to the pure polymer.
  • Processing lignocellulosic material originated from plants like trees or other agricultural feedstock with mechanical refiners is a known method to produce cellulose pulp.
  • Refiners use mechanical energy for disintegrating the plant tissue thus exposing the cellulose particles and fibers.
  • One method for measuring the degree of fiber formation by those skilled in the art is measuring the retention (or rate of drainage) of water using the method of Canadian standard freeness (CSF).
  • the degree of pulping can be controlled by type of equipment, by time and by concentration. Consistency is the measurement of amount of pulp in water expressed in weight percent.
  • FIG. 4A shows an illustrative size distribution of twin flow refiner fiber in accordance with an illustrative embodiment.
  • the output of the tornado pulper was fed in a twin flow refiner resulting a significant decrease in the CSF value to 209 ml.
  • This value of CSF below 300 ml indicates that processing the twin flow refiner has created a pulp in the range that is suitable for making paper products.
  • Increasing the time for processing with the twin flow refiner further reduced the value of CSF to as low as 157 ml. This shows that the degree of processing can be controlled by time to result in pulps with different degrees of pulp development.
  • FIG. 4B shows an illustrative size distribution of atmospheric refiner fiber in accordance with an illustrative embodiment.
  • Another method that can be used for producing hemp pulp using hemp hurd as a feedstock is atmospheric refiner. Processing the output of the tornado pulper with the atmospheric decreased the value of CSF from 583 ml to 291 ml. Increasing the consistency from 4% to 10% of the feedstock feeding the atmospheric refiner decrease the CSF from 291 ml to 190 ml.
  • FIG. 4C shows an illustrative size distribution of hurd, tornado pulper, and twin flow refiner samples in accordance with an embodiment.
  • Some common uses include several packaging applications: flexible packaging for use in food, shrink-film overwrap, electronic industry films, graphic arts applications, as well as disposable diaper tabs and closures. It is also blow-molded in rigid packaging in order to produce crates, bottles, and pots; consumer goods including translucent parts, housewares, furniture, appliances, luggage and toys; automotive applications such battery cases and trays, air ducts, shields and deflectors, bumpers, fender liners, interior trim, instrumental panels and door trims; fibers and fabrics such raffia/ slit-film, tape, strapping, bulk continuous filament, staple fibers, spun bond and continuous filament.
  • PP rope and twine are extraordinarily strong and moisture-resistant, being very suitable for marine applications.
  • PP is widely used in industrial applications to produce acid and chemical tanks, sheets, pipes, returnable transport packaging and other products.
  • PBAT is one such potential copolymer, which is a successful alternative for low-density polyethylene in applications such as plastic film for food packaging, compostable plastic bags for gardening and agricultural use and coatings for materials such as paper cups.
  • PBS results in materials that are not only biodegradable and eco-friendly but also possess desirable mechanical properties, making them suitable for a wide range of applications across various industries such as packaging materials, automotive components, construction materials, agricultural mulch films, textiles and apparel, consumer goods such as disposable cutlery, tableware, and household items, furniture, eco- friendly toys, and sporting goods.
  • the process described above may be automated, and controlled via a computer- implemented process control system as shown in FIG. 4D.
  • a process control system may include sensors and measurement tools to measure the hemp particles in one or more processing stages as described above.
  • Such a system may also be used to optimize the processing and/or formulation of the hemp particles with one or more thermoplastics or other additives to produce mold pellets for desired properties of an identified use case for a molded product.
  • the process control system may also obtain various measurements from tests of hemp plastic composite products to confirm that a formulation resulted in desirable properties for the molded product. These tests may include but are not limited to:
  • Tensile Testing This measures a material's resistance to a force pulling it apart. It assesses properties like tensile strength, elongation at break, and Young's modulus, which indicate how much a hemp plastic composite can stretch before breaking and its stiffness.
  • Flexural Testing This evaluates a hemp plastic composite's ability to bend without breaking. The most common method is the three-point bend test, which measures properties like flexural strength and modulus of elasticity.
  • Hardness Testing Hardness is a measure of a material's resistance to indentation or scratching. Common methods include Rockwell, Brinell, and Vickers hardness tests.
  • Density Measurement Determining a hemp plastic composite's density is essential for quality control. It can be measured using methods such as the displacement method or pycnometer.
  • MFI Melt Flow Index
  • DSC Differential Scanning Calorimetry
  • TGA Thermogravimetric Analysis
  • Hemp plastic composites may be exposed to various chemicals in their applications. Testing for resistance to specific chemicals may be essential to ensure product durability.
  • Hemp plastic composites may be subjected to UV radiation, humidity, and temperature variations. Environmental testing evaluates how these factors affect the material over time.
  • Dimensional Measurements Precise measurements of the product's dimensions, such as thickness and length, may be critical to ensure that a part meets design specifications.
  • Flammability Testing Assessing a hemp plastic composite's resistance to combustion for safety. Common tests include the UL 94 vertical bum test and oxygen index testing.
  • the process control system is configured to modify the hemp plastic composite formulation to determine a more appropriate mixture of the hemp particles with one or more thermoplastics.
  • the process control system may be assisted by an artificial intelligence (Al) / machine learning (ML) engine, embodied and executed on a computing device (e.g. as described below with reference to FIG. 6), to retain information about various different formulations of hemp particles and one or more thermoplastics, and utilize test data obtained from one or more tests as described above to provide feedback on how well a particular hemp plastic composite formulation matched desired reference properties for a use case.
  • An illustrative system incorporating an Al / ML engine is shown in FIG. 4D.
  • the feedback from the one or more tests as collected by sensors is provided as input data to the Al / ML engine, which may be one or more of text, images, sensor data, etc.
  • the test data may undergo preprocessing steps, such as cleaning, normalization, or feature extraction, as necessary for preparing the input data for analysis.
  • the Al / ML engine may comprise a neural network which processes and compares the test data against a desired set of parameters, and determines how successfully a hemp plastic composite formulation met the desired set of parameters. Over many iterations, a model is developed which minimizes the difference between the test data and the desired set of parameters, and the developed model is used to predict the probability that a particular hemp plastic composite formulation, or some change thereof, will result in a moulded product with the desired set of parameters or reference points.
  • the Al / ML engine may learn how changing the hemp particles and thermoplastics formulation and altering any parameters during the moulding process changes the characteristics of the molded parts, as measurable by one or more sensors for executing and measuring one or more of the above tests.
  • the trained model of the Al / ML engine is better able to recommend to the process control system a particular hemp plastic composite formulation and moulding process parameters for a particular use case.
  • the potential for using natural fibers as a reinforcement in composites is hampered due to the inherent incompatibility between hydrophilic fibers and the hydrophobic polymeric matrix resulting in poor fiber adhesion to the matrix.
  • the presence of 0.5% coupling agent, polypropylene grafted with maleic anhydride (MAH) has been shown to increase the compatibility between the polypropylene matrix and the fiber, resulting in a better reinforcement mechanism.
  • Hemp fibers from different parts of the process were considered in this invention: Hemp Hurd (fiber length between 2 to 4 cm), Tornado Pulper (TP), Twin Flow Refiner (TFR), Atmospheric Refiner (ATM), and Masuko Refiner (MR). In all these 0.5% compatibilizers were used with the exception of TP w/o MAH (without maleic anhydride compatibilizer).
  • FIG. 5B shows an illustrative Flexural modulus of the hemp fiber filled PBAT composites in accordance with an illustrative embodiment.
  • FIG. 5C shows an illustrative Flexural modulus of the hemp fiber filled PBS composites in accordance with an illustrative embodiment.
  • hemp fiber significantly increased the flexural modulus and tensile modulus of the samples.
  • the flexural modulus increased from 802.89 MPa to 1524.63 MPa with the addition of 20% hemp fiber when comparing the pure polybutylene succinate sample with the TFR sample, representing an increase of 89.89%.
  • the incorporation of fiber into matrix results in reduction in impact strength as fiber tends to hinder deformation and ductile mobility of polymer molecules which reduce the capability of composites to absorb energy during crack propagation.
  • FIG. 6 shown is a schematic block diagram of a generic computing device that may provide a suitable operating environment in one or more embodiments.
  • a suitably configured computer device, and associated communications networks, devices, software, and firmware may provide a platform for enabling one or more embodiments as described above.
  • FIG. 6 shows a generic computer device 700 that may include a central processing unit (“CPU") 702 connected to a storage unit 704 and to a random-access memory 706.
  • the CPU 702 may process an operating system 701, application program 703, and data 723.
  • the operating system 701, application program 703, and data 723 may be stored in storage unit 704 and loaded into memory 706, as may be required.
  • Computer device 700 may further include a graphics processing unit (GPU) 722 which is operatively connected to CPU 702 and to memory 706 to offload intensive image processing calculations from CPU 702 and run these calculations in parallel with CPU 702.
  • GPU graphics processing unit
  • An operator 710 may interact with the computer device 700 using a video display 708 connected by a video interface 705, and various input/output devices such as a keyboard 710, pointer 712, and storage 714 connected by an I/O interface 709.
  • the pointer 712 may be configured to control movement of a cursor or pointer icon in the video display 708, and to operate various graphical user interface (GUI) controls appearing in the video display 708.
  • GUI graphical user interface
  • the computer device 700 may form part of a network via a network interface 711, allowing the computer device 700 to communicate with other suitably configured data processing systems or circuits.
  • a non-transitory medium 716 may be used to store executable code embodying one or more embodiments of the present method on the generic computing device 700.
  • hemp hurd is mechanically processed to decrease its particle size using mechanical refiners, creating fiber and particles that have CSF less than 300 ml.
  • This formulation of plastic and hemp has improved mechanical performance and other desirable properties compared to the pure plastics and is therefore suitable for various use cases for molded products.
  • a method of producing a mouldable hemp plastic composite comprising: sourcing hemp hurd; utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired Canadian standard freeness (CSF) measurement; and formulating a composite plastic comprising a combination of the hemp particles and one or more thermoplastics.
  • CSF Canadian standard freeness
  • the method further comprises identifying a use case for a molded product; and formulating the composite plastic comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product.
  • the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
  • the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, and insulation properties.
  • a method of producing a mouldable hemp plastic composite comprising: i) sourcing hemp hurd; ii) processing the hemp hurd utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired freeness measurement; and iii) formulating a hemp plastic composite comprising a combination of hemp particles processed in step ii) with one or more thermoplastics.
  • the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
  • CSF Canadian standard freeness
  • the hemp hurd is sourced from a Cannabis sativa plant.
  • the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
  • the method further comprises processing a mixture of hemp particles and one ore more thermoplastics between 100 °C to 230 °C.
  • the method further comprises: a) identifying a use case for a molded product; and b) formulating the composite plastic comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product.
  • the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
  • the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, dimensional conformity, thermal properties, chemical properties, and electrical properties.
  • a process control system adapted to control a process for performing the method in accordance with claim 1.
  • the process control system receives feedback from test measurements comprising one or more of tensile testing, flexural testing, impact testing, hardness testing, density measurement, melt flow index, thermal analysis, chemical resistance, environmental testing, dimensional measurements, flammability testing, and electrical properties testing.
  • the system incorporates an artificial intelligence (Al) / machine learning (ML) engine which may be trained on feedback from the test measurements to determine which hemp plastic composite formulations result in the desirable properties for one or more use cases.
  • Al artificial intelligence
  • ML machine learning
  • the AI/ML engine is adapted to recommend a hemp plastic composite formulation for a given use case.
  • the AI/ML engine is further adapted to guide the process control system to control the proportion of hemp particles to one or more thermoplastics.
  • the AI/ML engine is further adapted to guide the process control system to control the proportion of hemp particles, one or more thermoplastics, and one or more additives to achieve desirable properties for one or more use cases.
  • the AI/ML engine is further adapted to recommend control settings for the mixing process, the mixing temperature, and the subsequent moulding process.
  • a mouldable hemp plastic composite formulation comprising: a) hemp particles sourced from the hemp hurd, the hemp particles having a desired freeness measurement; and b) one or more thermoplastics.
  • the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
  • CSF Canadian standard freeness
  • the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
  • the mouldable hemp plastic composite formulation further comprises one or more additives to achieve desirable properties for one or more use cases.
  • the hemp hurd is sourced from a Cannabis sativa plant. While various illustrative embodiments of the system, method, and apparatus have been described, it will be appreciated that various modifications and amendments may be made without departing from the scope of the invention.

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Abstract

This disclosure describes the method for preparation of hemp fiber and thermoplastic composites and their formulations. Hemp feedstock is processed with mechanical refiners and then compounded with plastics that have a reduced environmental footprint because they are recycled or biodegradable. The resulting product has a formulation containing hemp fiber or particles in a matrix of recycled or biodegradable thermoplastic that can be manufacturing using injection molding, compression molding or other molding methods.

Description

ENVIRONMENTALLY FRIENDLY HEMP PLASTIC COMPOSITE FORMULATIONS AND MOLDING METHODS
REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 63/427,980, filed on November 25, 2022, and entitled ENVIRONMENTALLY FRIENDLY HEMP PLASTIC COMPOSITE FORMULATIONS AND MOLDING METHODS, the entirety of which is incorporated herein by reference.
FIELD
The present disclosure relates to hemp fiber, and novel formulations and processes for the manufacture of plastic composites incorporating hemp fiber, and molding methods for making useful articles therefrom.
BACKGROUND
Plastics and resins are very versatile because they enable a wide variety of useful articles to be made to meet many applications. This demand for plastic molded products can be found in housing, transportation, packaging, health care, energy, nutrition, communications, and many other sectors. In housing for example, furniture, flooring, windows and doors, and fixtures can be manufactured by injection molding, compression molding or extrusion. In transportation, parts for vehicles can be molded from plastics to the exact shapes required to enable functionality and safe operation of vehicles.
Most plastics and resins are made with petroleum feedstock, which is non-renewable, or do not biodegrade. The negative environmental impacts of such non-renewable plastic waste are well known, including widespread pollution in lakes, seas and oceans, injuries to wildlife, and contribution to air pollution when plastic waste is incinerated. Recycling plastics has an environmental appeal because recycling turns the waste plastic into a useful product, thus eliminating the disposal of plastic waste in landfill, and preventing plastic waste from polluting the oceans.
New ways to mitigate the detrimental effect of plastics on the environment are needed at a product’s beginning by selecting renewable feedstock, or at a product’s end-of-life by selecting materials that are either biodegradable or recyclable. Efforts in this direction have been made by using renewable feedstock for manufacturing common plastics, like the example of polyethylene utilizing ethylene monomer made from bioethanol or creating monomers by fermentation methods which then are made into polymers or copolymers which are then biodegradable, like the examples of poly (lactic acid) (PLA), polybutylene succinate (PBS), or recycling the end products, like for example in the cases of recycled polypropylene (PP) or recycled polyethylene terephthalate (PET). However, these processes may be complicated, and may take a long time to neutralize their impact.
Therefore, what is needed are improvements in plastic composite formulations and manufacturing methods which reduce the amount of non-biodegradable plastics, and enable such plastic composites to be highly recyclable, thereby significantly reducing their environmental impact.
SUMMARY
The present disclosure relates to hemp fiber, and novel formulations and processes for the manufacture of plastic composites incorporating hemp fiber, and molding methods for making useful articles therefrom.
In another aspect, there is provided a method of producing a mouldable hemp plastic composite, comprising: i) sourcing hemp hurd; ii) processing the hemp hurd utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired freeness measurement; and iii) formulating a hemp plastic composite comprising a combination of hemp particles processed in step ii) with one or more thermoplastics.
In an embodiment, the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
In another embodiment, the hemp hurd is sourced from a Cannabis sativa plant.
In another embodiment, the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
In another embodiment, the method further comprises processing a mixture of hemp particles and one or more thermoplastics between 100 °C to 230 °C.
In another embodiment, the method further comprises: a) identifying a use case for a molded product; and b) formulating the plastic composite comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product. In another embodiment, the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
In another embodiment, the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, dimensional conformity, and thermal, chemical, and electrical properties.
In another aspect, there is provided a process control system adapted to control a process for performing the method in accordance with claim 1.
In an embodiment, the process control system receives feedback from test measurements comprising one or more of tensile testing, flexural testing, impact testing, hardness testing, density measurement, melt flow index, thermal analysis, chemical resistance, environmental testing, dimensional measurements, flammability testing, and electrical properties testing.
In another embodiment, the system incorporates an artificial intelligence (Al) / machine learning (ML) engine which may be trained on feedback from the test measurements to determine which hemp plastic composite formulations result in the desirable properties for one or more use cases.
In another embodiment, the AI/ML engine is adapted to recommend a hemp plastic composite formulation for a given use case.
In another embodiment, the AI/ML engine is further adapted to control the proportion of hemp particles to one or more thermoplastics.
In another embodiment, the AI/ML engine is further adapted to control the proportion of hemp particles, one or more thermoplastics, and one or more additives to achieve desirable properties for one or more use cases.
In another embodiment, the AI/ML engine is further adapted to recommend control settings for the mixing process, the mixing temperature, and the subsequent moulding process.
In another aspect, there is provided a mouldable hemp plastic composite formulation, comprising: a) hemp particles sourced from the hemp hurd, the hemp particles having a desired freeness measurement; and b) one or more thermoplastics.
In an embodiment, the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml. In another embodiment, the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
In another embodiment, the mouldable hemp plastic composite formulation further comprises one or more additives to achieve desirable properties for one or more use cases.
In another embodiment, the hemp hurd is sourced from a Cannabis sativa plant.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the illustrative embodiments set forth in the following description or illustrated in the drawings. Therefore, it will be appreciated that a number of variants and modifications can be made without departing from the teachings of the disclosure as a whole.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention, and the objects of the invention will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, wherein:
FIGS. 1A - 1C show a schematic overview of processes in accordance with illustrative embodiments.
FIG. 2 shows an illustrative bar graph of size distributions of hemp Hurd fiber as measured by the opening in micrometers in accordance with an illustrative embodiment.
FIG. 3 shows an illustrative bar graph of size distributions of Tornado Pulper (TP) fiber as measured by the opening in micrometers in accordance with another illustrative embodiment.
FIG. 4A shows an illustrative bar graph of size distributions of Twin Flow Refiner (TFR) fiber as measured by the opening in micrometers in accordance with another illustrative embodiment.
FIG. 4B shows an illustrative bar graph of size distributions of Atmospheric Refiner (ATM) fiber as measured by the opening in micrometers in accordance with another illustrative embodiment. FIG. 4C shows an illustrative line graph of size distributions of Hurd, TP, and TFR samples in accordance with an illustrative embodiment.
FIG. 4D shows an illustrative process for utilizing an Al / ML engine to iteratively improve the hemp plastic composite formulation and a corresponding moulding process.
FIGS. 5A - 5C show an illustrative bar graph of a comparison of the flexural modulus of different samples of materials used in testing in accordance with an illustrative embodiment.
FIG. 6 shows a schematic block diagram of a generic computer system which may provide an operating environment for one or more embodiments.
In the drawings, embodiments are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding and are not intended as describing the accurate performance and behavior of embodiments and a definition of the limits of the invention.
DETAILED DESCRIPTION
As noted above, the present disclosure relates to hemp fiber, novel formulations and processes for the manufacture of plastic composites incorporating hemp fiber, and molding methods for making useful articles therefrom.
Natural fibers are renewable, recyclable and have low specific gravity when compared to minerals, such as talc or calcium carbonate, or compared to glass fibers. In addition to hemp fiber, other natural fibers that have been explored to decrease the environmental impact of plastic composites include, wood fiber, jute, sisal, coconut, and straw for example.
Industrial hemp has a growing and harvesting cycle that is much shorter than trees, which enables the production of more biomass per hectare per year. Industrial hemp can be used to produce long fibers with applications in ropes and twines, textiles, and non-woven fiber products. Long fibers can be removed from industrial hemp main stock using a process of decortication to produce clean fibers with lengths longer than 10 cm . Depending on the type of industrial hemp and the type of decortication process, the stalk of industrial hemp can yield long fibers in the range of about 10-20 wt.%. FIG. 1A illustrates steps for production of hemp fiber in accordance with an embodiment. Industrial hemp crop is a plant that has a relatively thin stalk that can be mechanically or manually harvested. The hemp leaves and grains can be separated from the stalk during harvesting. The hemp stalk can then be submitted to a process known as decortication. This process mechanically separated the bast fiber and hurd, and a certain amount of dust is produced as a by-product. The materials produced during the decortication process are bast and hurd fiber.
In accordance with an embodiment, a mechanical method is used for separating bast fiber and hurd fiber using the hemp stalk as a feedstock. This method is described in further detail below.
After the decortication process generates the bast fiber, the remainder of the material produced during the decortication process is composed of fine dust and hurd. Fine dust has atypical particle size smaller than 2 mm. Hurd is produced as a by-product of decortication to be 50 wt.% or more, depending on type of industrial hemp and decortication process. Hurd produced during the decortication process generally has a size larger than 2 mm, and smaller than 10 cm. Although hurd is rich in cellulose, it is often considered a waste product produced during the production of long bast fibers from industrial hemp. While hurd has been used to produce energy pellets or sorbent materials, other uses for hurd are not common.
Fibers rich in cellulose can be produced by chemical or mechanical methods using processes known as pulping. Chemical pulping produces cellulose fibers of high quality by chemically removing lignin, but the process requires utilization of chemicals. Cellulose is separated from lignin in the chemical pulping process. Immediately after separation from cellulose, lignin is mixed with chemicals. The reparation of the lignin from chemicals after chemical pulping requires further processing to recover the chemicals.
Mechanical pulping produces cellulose fibers without the use of chemicals. Special equipment is used to separate fibers using physical forces. One type of equipment used in mechanical pulping is a refiner. The mechanical pulping process is cleaner than chemical pulping because it does not require handling chemicals and it does not produce any chemical waste that would require further processing. The fibers produced by mechanical pulping contain cellulose and lignin. The refiner uses mechanical stresses to produce cellulose fibers containing lignin. One advantage of the mechanical pulping method is the absence of chemicals or by-products. The invention presented here is described by a mechanical method to process hemp bast fiber, hurd or hemp stalk to generate hemp fiber without the use of chemical. The main aspect of the production of hemp fiber is the utilization of mechanical equipment knows as refiners. The hemp feedstock, composed of bast fiber, hurd or simply hemp stalk, is fed into and equipment known as tornado pulper. Then the material is further processed with other types of refiners to further reduce the diameter of the fibers. Water is also utilized in this process. Typical types of refiners are tornado pulper, atmospheric refiner, twin flow refiner, or Masuko refiner.
FIG. IB shows the flow diagram for the process utilizing hemp hurd fiber as a feedstock and mechanical methods including a tornado pulper, screw press, atmospheric refiner, twin flow refiner and Masuko refiner. The role of the refiners is to reduce fiber diameter while increasing its quality. The role of the screw press is to adjust the amount of water required in the process.
Plastics are often mixed with other ingredients when manufacturing composite products. Fillers or fibers can be added to the formulation of plastic composites to control properties and other attributes. Mineral fillers such as talc, mica or calcium carbonate are typically added to increase rigidity of the final product. Glass fiber can be added to the formulation of plastics to increase rigidity and strength. Short glass fiber has a length typically smaller than 10 mm . When the plastics containing glass fiber are pelletized, the length of glass fiber is the same or smaller than the pellet. Plastic pellets often have 3 to 4 mm in diameter and 2 to 10 mm in length, although other sizes are also possible.
Cellulose fibers sourced from forestry or agriculture have been used as filler or reinforcing agents in plastics as well. These cellulose fibers can be prepared by gridding, milling, or pulping. The type of process selected for manufacturing fibers is responsible for determining their characteristics like length and aspect ratio of the cellulose fibers. These characteristics of the cellulose fibers can affect rigidity, strength, and other properties of the final plastic composites, such as impact resistance, wear resistance, deformability, and insulation properties.
In an embodiment, a sustainable hemp plastic composite product and a process for its preparation is disclosed in which industrial hemp is carefully selected and processed with specific mechanical methods and then combined preferably with recycled plastics or biodegradable plastics. The product and process address a need for mouldable thermoplastics with a low environmental footprint.
Fibers produced from industrial hemp are renewable. Hence addition of hemp fibers to thermoplastic composites increases the quantity of renewable content in the thermoplastics thus decreasing its environmental footprint. In another embodiment, a mechanical refining process is employed to produce cellulose fibers and particles using industrial hemp hurd. The fibres and particles produced from hurd feedstock herein can improve the mechanical properties of plastics. The mechanical stiffness and strength of these composites containing cellulose fibers produced from industrial hemp hurd are superior to the properties of the same thermoplastics without these added materials. These hemp plastic composites also have a lower environmental footprint because their components are mainly either renewable, or recycled or biodegradable, and provide a unique pathway for producing mouldable thermoplastic composites from an environmental perspective.
FIG. 1C shows the flow diagram for the process necessary for manufacturing mouldable thermoplastics composites. The process starts by selecting a grade of fiber obtained from processing hemp with refiners. These fibers are obtained in water; hence a dryer is utilized to decrease the moisture content below 5 wt.%. The dried fibers are mixed with polymer and additives to exact quantities to achieve a desirable formulation. The mixture is then fed into equipment to mix all ingredients in the formulation while melting the thermoplastic polymer using heat. At the end of the extrusion machine the product is cooled down to room temperature and cut into pellets. The pellets contain a homogenous mixture of all ingredients including the hemp fiber. The pellets are stable and can be stored for a long time when needed. The moisture level in pellets can increase during storage. The pellets can be dried prior to injection molding to achieve a moisture level below 2 wt.%. The dried pellets are then fed into an injection molding machine equipped with a mold to manufacture the final product consisting of a recycled or biodegradable plastics, additives, and hemp fibers. Different grades of thermoplastics, additives, and hemp fiber can be combined during the above- mentioned process to achieve a balance of optimal performance while decreasing the environmental footprint.
Through extensive experimentation, the inventors have identified the following key factors that contribute to lowering the environmental footprint: a) selection of industrial hemp hurd that is considered as a waste of producing long hemp fiber. b) processing industrial hemp hurd with mechanical refiner to produce fiber or particles without the use of chemical or creation of by-products. c) incorporation of renewable hemp fiber or particles in the formulation of recycled or biodegradable thermoplastics with extrusion. d) producing a mouldable formulation with superior mechanical properties.
The resulting hemp plastic composite product is suitable for manufacturing a wide range of mouldable parts useful for transportation, furniture, packaging, and other industrial applications that can benefit from a material and a process with low environmental impact. Illustrative embodiments will be described below with reference to tables and figures.
Now referring to FIGS. 1A - 1C, a schematic overview of aprocess according to an illustrative embodiment is shown. The stages of the process are as follows:
1. Selection of hemp hurd, describe origin from decortication, size, and composition
2. Mechanical pulping, describe tornado pulper and refiners, list sequence of steps to produce hemp fibers and particles (fines)
3. Selection of recycled PP (polypropylene) , PBAT (polybutylene adipate-co-terephthalate) and PBS (polybutylene succinate)
4. Formulation of composites (resin, hemp, coupling agent, antioxidant)
5. Compounding with extrusion
6. Injection and Compression Molding
7. Measurement of performance of molded parts (e.g., elasticity or stiffness, hardness, fracture resistance, fatigue strength, tensile strength, wear strength, thermal properties, etc.) and feedback to further improve the formulation for particular use cases.
Each of these stages will now be described in more detail below.
1. Selection of hemp hurd. describe origin from decortication, size, and composition
The selection of the hurd is relevant because it determines the particle size, morphology, and the chemical composition of the hemp hurd used in a composite material. Characteristics of the chemical composition of the hemp hurd may include the quantities of cellulose, hemicellulose, lignin, moisture, and various other components.
In selecting a suitable hemp plant, the morphology of the plant tissue is very relevant, including the arrangement and geometry of cells, determining the orientation of the cell and fibers within the plant tissue. These attributes affect the composition because they will determine thermal properties, strength, and crystallinity of the finished molded product. Hemp plants contain different parts: roots, stalk, leaves, flower, and seeds.
In an embodiment, a hemp plastic composite formulation uses a part of the stalks, more specifically the hemp hurds. Hemp hurds are the woody inner parts of the hemp stalk and can be broken into fragments and separated from the long fiber by breaking and scutching them. The outcome of this process is the separation of three main fractions: long fibers, hurd and dust. Hurd is selected for this technology due to its characteristics, abundance, and size.
The particle size of hemp hurd from decortication is commonly between 0.5 cm and 10 cm, with elongated shape. The competitive advantage of proper selection of feedstock resides in its high yield after the decortication process, the absence of dust and other impurities (leaves and flowers), the amount of crystallinity and thermal stability.
FIG. 2 shows an illustrative size distribution of hemp hurd fiber in accordance with an embodiment.
2, Mechanical pulping, describe tornado pulper and refiners, list sequence of steps to produce hemp fibers and particles (fines)
The hurd selected in stage 1 as described above is the feedstock for the processing with mechanical refiners. In an embodiment, the process is based on rotating discs that can decrease the particle size of hurd while producing particles with high aspect ratio due to shearing forces produces between the two discs and feedstock. This is fundamentally different than decreasing particle size of hurd by hammer milling or ball milling, as may be used in the prior art. The hurds are first processed on an equipment known as tornado pulper in high dilution to decrease the particle size to less than 2 cm, and the output of the tornado pulper is fed in high dilution into a disc refiner to further decrease the particle size while maintaining the aspect ratio. The dilution is a dispersion of hemp in water measured as consistency.
The particle produced after processing through the disc refiner can have the appearance of fibers or plates, accompanied by a somewhat small number of fine particles with low aspect ratio. The combination of such particle shapes, sizes and aspect ratios is unique to the combination of processes utilized in its manufacture. The materials produced in this process is rich in hemp fiber. The diameter of the particles produced by the disc refiners is less than 0.5 cm, or better yet, less than 0. 1 cm, or even less than 0.05 cm. Then, the aspect ratio of fiber may be measure by optical microscopy resulting in a distribution of values between approximately 1 and 30.
FIG. 3 shows an illustrative size distribution of tornado pulper fiber in accordance with an embodiment.
The reduction of size and the increase in aspect ratio result in an increase in surface area for a given mass amount of product. The resulting increase in surface area can create porosity with capacity to retain water due to capillary forces. With reference to Table 1 below, Canadian standard freeness from hemp h rd refining, the resulting material can retain water as measured by the Canadian Standard Freeness values between 583 and 157.
Sample Identification Canadian Standard Freeness (ml)
Tornado Pulper - Screw Press 583
Twin Flow Refiner (0 min) 209
Twin Flow Refiner (3 min) 180
Twin Flow Refiner (9 min) 157
Atmospheric Refiner (4%) 291
Atmospheric Refiner (10%) 190
Table 1
The production of hemp materials containing fibers, small particles, high aspect ratio and high surface area is highly desirable for application in composites because of its capacity to transfer and carry mechanical loading in composites with thermoplastics.
3, Selection of recycled PP. PBAT and PBS, use data from literature for LCA of each
A competitive advantage for products manufactured with thermoplastics is related to its reduced environmental footprint. This is particularly relevant with respect to packaging, consumer goods and other markets that require products with a relatively short lifetime. Examples in this category are packaging for consumer goods. This is fundamentally different than plastics used for building infrastructure with expected long lifetime - one example of this is plastic for water pipes.
A key factor of the hemp plastic composite technology developed here is the selection of recycled thermoplastic or compostable thermoplastic. Recycled polypropylene is a resin that has reduced environmental footprint because it does not require using new petroleum feedstock and avoids plastic scrap going to landfills. PBAT is a compostable thermoplastic, its utilization is advantageous when the product is contaminated and does not lend itself for recycling. PBS is a biodegradable synthetic polymer that is often used to create environmentally friendly and sustainable materials.
4, Formulation of composites (resin, hemp, coupling agent, antioxidant) Hemp particles as described herein are preferably produced from hemp h rd processed by disc refiners. The utilization of disc refiners allows a desirable particle size to be achieved and is believed to be a unique characteristic of the present hemp plastic composite technology. During testing, the inventors found that disc refiners are especially well suited as it modifies the properties of hemp fibers mechanically. Similar technologies utilizing disk and conical geometries which operate in the same way may also be used. Generally, such technologies may use a disk with cutting blades on the rotating surface, and a stationary disk also with blades. The blade design is a determining factor for refiner efficiency. That is to say, the raw material and type of fiber treatment are considered to calculate the appropriate blade design. During cutting, when the laminae cross, the desired fiber treatment is promoted. The design of the blades is made according to the desired treatment, which can be high fibrillation, cutting or some combination of these. The fibers dispersed or diluted in water then pass between the discs and receive the required treatment. The high aspect ratio of fibers is among the most important properties making this material a good reinforcement filler. Avoiding fiber breakage during the dispersion process is essential to achieve superior enforcement.
Advantageously, hemp hurd is a renewable material which contributes to further decreasing the environmental footprint of thermoplastics.
The composition of the matter is relevant because it controls the environmental footprint and the performance of the product. The preferrable, but not limited to, formulations relevant to the technology developed here makes of at least 80 % containing ingredients with reduced environmental footprint and no more than 20 % of other ingredients with the objective to further increase other properties. These other ingredients can be used, but are not limited to, improving thermal stability, flow of plastic during molding, strength of plastic goods and appearance.
5 , Compounding with extrusion
The help plastic composite technology used here makes use of extruder (e.g., a twin-screw extruder) or other polymer mixing equipment can be used to melt the thermoplastics and mixing all ingredients. The equipment can be continuous or batch. In an embodiment, melting and mixing may be achieved using a twin-screw extruder producing a pellet of thermoplastic, hemp, and additives.
The feedstock of hemp particles produced in stage 1 as described above have sufficient thermal stability to avoid thermal degradation when processed with compounding extrusion to temperatures up to 230°C. This hemp feedstock may be prepared with a particular particle size and shape to ensure that its loading into the extrusion equipment is feasible, and it does not increase the viscosity of the molten plastic mixture to exceed the extrusion equipment capacity. After melting and mixing thermoplastics, hemp feedstock, and additives, the material is pelletized.
Some examples of additives include compatibilizer, waxes, and lubricants. Using a compatibilizer that works between the hemp fibers and the polymer increases adhesion between the two materials, and consequently result in improved mechanical properties with stiffness and strength. To create a strong composite, there must be good adhesion between the polymers and fibers. To achieve this, they need to come in close contact, have appropriate surface tensions and, in most cases, have the same chemical polarity.
Weak adhesion is one of the biggest difficulties along with breakage and alteration of morphology between natural fibers in the polymer. This can be because natural fibers have low thermal stability, and high susceptibility to moisture as well as they experience fiber decomposition during compounding. Some other factors that affect bonding that should be considered are atomic arrangement, chemical properties, molecular conformations, and chemical constitution.
Fiber dispersion is also an important factor to consider in the performance of composites as well using some waxes and lubricants, or other additives, to improve fiber dispersion and reduce hydrogen bonding.
In addition, mixing and dispersing natural fibers into polymers is a challenge. The strategy used was to add polymers to the dry hemp fibers (preferably maximum 0.2% moisture, but not limited to) to avoid blistering and cracking that could be caused by the evaporation of moisture in the fibers during injection molding.
An illustrative formulation is shown in Table 2, below.
Sample ID Fiber Description Fiber (%) Rec-PP (%) MAH (%)
Rec'PP - - 100.0
Hurd Hemp Hurd 20.0 79.5 0.5 p Tornado Pulper 20.0 79.5 0.5
TP w/o MAH Tornado Pulper 20.0 80.0
TFR Twin Flow Refiner 20.0 79.5 0.5
A™ Atmospheric Refiner 20.0 79.5 0.5
MR Masuko Refiner 20.0 79.5 0.5
Table 2 Table 3, below, shows the results of mechanical tests with recycled polypropylene (Rec-PP) without the use of hemp fibers and with the use of hemp fibers obtained at different stages and mechanical refiners.
„ . T_ Impact strength Flexural strength Flexural modulus
Samples ID (j/m) (MPa) (MPa)
Rec-PP 43.54 ± 4.04 c 36.83 ± 1.72 a b 1096 ± 111 a
Hurd 23.49 ± 1.04 a b 38.00 ± 1.90 b c 1439 ± 111 b c
TP 23.85 ± 2.32 ab 36.67 ± 1.37 ab 1493 ± 106 b c
TP w/o MAH 27.03 ± 2.08 b 32.83 ± 1.33 a 1341 ± 169 b
TFR 23.16 ± 3.29 a b 39.17 ± 4.12 b c 1539 ± 66 c
ATM 21.62 ± 0.34 a 39.17 ± 1.17 b c 1530 ± 51 c
MR 21.49 ± 1.84 a 41.83 ± 2.14 c 1477 ± 76 b c
Mean ± standard deviation (10 repetitions). Note: average with the same letter in the same column indicates no significant difference (p < 0.05) by Tukey test.
Table 3
6, Injection and Compression Molding
The pellets produced in stage 5 as described above are suitable for processing with conventional molding processes found the plastics manufacturing industry. The pellets present adequate flow behavior to enable processability by compression molding or injection molding in cycle times shorter than preferably 1 minute. This is due to the selection of the formulation and material characteristics as described above. More specifically, the particles of hemp produced in stage 2 as described above have adequate size, shape, and aspect ratio to have a minimal effect on the flow properties of the compounded formulation.
The addition of short hemp fibers can be carried out in different percentages, normally between about 5% and 30% by weight, but also reaching 50% of the weight of the final material. This amount of short hemp fiber selected should occur according to the particular industrial applications (automotive, construction materials, external applications, etc.) of the composites and their destination (i.e., environmental conditions such as temperature and humidity, and exposure to sunlight). For example, in the automotive industry, different percentages may be used for indoor and outdoor applications in automobiles. 7, Measurement of performance of molded parts (mechanical properties)
The addition of hemp particles to the formulation of thermoplastics produces plastic composites with physical properties that are improved in comparison to the properties of the thermoplastics used to make such composites. For example, the flexural strength of PBAT is 4 MPa and the thermoplastic composite of PBAT with 20% hemp processed by the atmospheric refiner is 16 MPa. This represents an increase of 400% in the physical property.
The incorporation of fiber into matrix results in reduced impact strength as fiber tends to hinder deformation and ductile mobility of polymer molecules, which reduce the capability of composites to absorb energy during crack propagation. As an example, Table 4, below, shows results of flexural properties and Izod impact strength with polybutylene adipate-co-terephthalate (PBAT) without hemp fibers and with hemp fibers obtained at different stages and mechanical refiners.
Impact strength Flexural strength Flexural modulus
Sample ID /T/ \
F (J/m) (MPa) (MPa)
PBAT 208.26 ± 21.27 c 4.00 ± 0.05 a 65.80 ± 7.01 a
Hurd 109.33 ± 23.65 b 12.75 ± 0.50 c 288.25 ± 10.87 c
TP 76.96 ± 10.13 a 12.67 ± 1.03 c 352.33 ± 50.63 d
TFR 51.93 ± 2.85 a 14.50 ± 0.58 d 453.00 ± 4.97 e f
ATM 51.38 ± 6.38 a 16.17 ± 0.75 e 511.83 ± 38.53 f
MR 10% 66.06 ± 4.11 a 9.50 ± 0.55 b 198.33 ± 25.00 b
MR 20% 65.09 ± 5.57 a 18.30 ± 0.10 f 446.83 ± 28.58 e
Mean ± standard deviation (10 repetitions). Note: average with the same letter in the same column indicates no significant difference (p < 0.05) by Tukey test.
Table 4
Table 5 below shows illustrative tensile properties of hemp fiber filled PBAT composites.
„ . T_ Tensile strength Tensile modulus Elongation at break
Sample ID (MPa) (MPa) (%)
PBAT 10.00 ± 0.01 b 47.00 ± 2.16 a 38.0 ± 0.1 c
Hurd 11.25 ± 0.50 c d 99.75 ± 4.57 cd 18.6 ± 2.5 a b
TP 8.67 ± 0.52 a 92.50 ± 8.14 b c 16.8 ± 2.7 a
TFR 10.67 ± 0.82 b c 111.67 ± 8.87 d e 13.6 ± 1.5 a
ATM 11.83 ± 0.41 d 118.83 ± 8.93 e f 14.5 ± 1.6 a
MR 10% 10.40 ± 0.55 bc 82.20 ± 3.03 b 23.8 ± 3.1 b
MR 20% 17.00 ± 0.01 e 126.50 ± 1.64 f 15.3 ± 0.8 a
Mean ± standard deviation (10 repetitions). Note: average with the same letter in the same column indicates no significant difference (p < 0.05) by Tukey test.
Table 5
Table 6 illustrates the results of flexural properties and Izod impact strength using polybutylene succinate (PBS) without hemp fibers and with hemp fibers acquired at various stages and mechanical refiners as an example.
Impact strength Flexural strength Flexural modulus
Sample ID ,T/ .
F (J/m) (MPa) (MPa)
PBS 28.53 ± 3.15 b 37.22 ± 0.67 a 802.89 ± 18.83 a
Hurd 14.75 ± 2.03 a 51.40 ± 3.60 b 1142.60 ± 55.20 b
TP 14.43 ± 2.32 a 54.50 ± 0.93 b 1273.25 ± 38.39 c
TFR 12.22 ± 1.59 a 59.50 ± 1.58 c 1524.63 ± 41.50 d
ATM 12.05 ± 1.26 a 59.89 ± 3.86 c 1514.33 ± 37.54 d
Mean ± standard deviation (10 repetitions). Note: average with the same letter in the same column indicates no significant difference (p < 0.05) by Tukey test.
Table 6
Table 7 below depicts the tensile properties of hemp fiber filled PBS composites.
Tensile strength Tensile modulus Elongation at break (MPa) (MPa) (%)
PBS 32.60 ± 3.40 a 114.75 ± 14.38 a 35.50 ± 3.72 c
Hurd 31.25 ± 0.96 a 123.50 ± 16.87 a 27.57 ± 3.51 b
TP 29.00 ± 3.24 a 130.50 ± 3.27 a 21.78 ± 2.49 ab
TFR 31.14 ± 2.91 a 152.86 ± 412.47 a b 19.70 ± 1.25 a
ATM 36.00 ± 2.35 a 176.17 ± 15.14 b 19.11 ± 1.54 a
Mean ± standard deviation (10 repetitions). Note: average with the same letter in the same column indicates no significant difference (p < 0.05) by Tukey test. Table 7
In an embodiment, the performance of molded parts is tested for various performance measurements (e.g., elasticity or stiffness, hardness, fracture resistance, flexural strength, fatigue strength, tensile strength, wear strength, thermal properties, etc.) and feedback from the testing is utilized as an input to further improve the formulation of the composite for particular use cases.
In testing, the composites fdled with the developed hemp fibers showed promising results in relation to their mechanical properties, enhancing their applications in injection molded parts for the automotive and furniture industries. In test materials studied by the inventors, the addition of 20% hemp fiber increased the tensile modulus of the composites as well as their flexural modulus. Regarding the flexural modulus, the increase was up to 140 % in the recycled polypropylene, 190 % in the polybutylene succinate, and 778% in the polybutylene adipate terephthalate when compared to the pure polymer.
Examples
Processing lignocellulosic material originated from plants like trees or other agricultural feedstock with mechanical refiners is a known method to produce cellulose pulp. Refiners use mechanical energy for disintegrating the plant tissue thus exposing the cellulose particles and fibers. One method for measuring the degree of fiber formation by those skilled in the art is measuring the retention (or rate of drainage) of water using the method of Canadian standard freeness (CSF).
The Canadian Standard Freeness (CSF): the freeness of pulp is related to the surface conditions and swelling of the fibers and is a measurable index of the refining degree of pulps. It is possible to relate that the lower the CSF value, the smaller the particle size of the refined fibers. For example, tensile modulus and flexural modulus of recycled polypropylene, PBS and PBAT composites were significantly increased by the addition of hemp fiber. This variation indicated increasing values in the smaller size fibers added to the polymeric matrix, varying according to the type of fiber studied (Hurd, TP, TFR, ATM or MR).
Increasing the intensity of mechanical refining decreased the number of milliliters of water measured in the CSF, as shown in Table 1. The process of mechanical decortication is used to separate hemp stalk in long fibers, h rd and dust. The amount of hemp hurd produced by decortication is higher than 50%. Hemp hurd obtained after decortication of industrial hemp grown in Canada was used for processing with mechanical refiners.
The degree of pulping can be controlled by type of equipment, by time and by concentration. Consistency is the measurement of amount of pulp in water expressed in weight percent.
Processing hemp hurd with tornado pulper produced a CSF value of 583 ml. This indicates that the tornado pulper can provide an initial level of refining creating a coarse hemp pulp. Further refining and formation of more hemp fiber was obtained by using other types of refiners and by increasing the time of refining.
FIG. 4A shows an illustrative size distribution of twin flow refiner fiber in accordance with an illustrative embodiment.
The output of the tornado pulper was fed in a twin flow refiner resulting a significant decrease in the CSF value to 209 ml. This value of CSF below 300 ml indicates that processing the twin flow refiner has created a pulp in the range that is suitable for making paper products. Increasing the time for processing with the twin flow refiner further reduced the value of CSF to as low as 157 ml. This shows that the degree of processing can be controlled by time to result in pulps with different degrees of pulp development.
FIG. 4B shows an illustrative size distribution of atmospheric refiner fiber in accordance with an illustrative embodiment.
Another method that can be used for producing hemp pulp using hemp hurd as a feedstock is atmospheric refiner. Processing the output of the tornado pulper with the atmospheric decreased the value of CSF from 583 ml to 291 ml. Increasing the consistency from 4% to 10% of the feedstock feeding the atmospheric refiner decrease the CSF from 291 ml to 190 ml.
The examples discussed above are summarized in the tables. They indicate that these methods can decrease the size of hemp hurd originated from decortication and turn it into smaller fibers that have CSF in the range of 583 ml to 157 ml. These values of CSF are in the range of pulps that can be used for making paper products. Although the intention here is not specifically to use the produced pulp to make paper, the use of CSF is adequate to measure the speed of drainage of pulp produce from wood or pulp from other plants. CSF is widely used to measure drainage in wood pulp. The method of CSF is used here to measure the drainage of hemp fibers produced in this embodiment. FIG. 4C shows an illustrative size distribution of hurd, tornado pulper, and twin flow refiner samples in accordance with an embodiment.
Illustrative Use Cases
The following use cases describe various illustrative examples of how the above described plastic composite materials may be used.
Some common uses include several packaging applications: flexible packaging for use in food, shrink-film overwrap, electronic industry films, graphic arts applications, as well as disposable diaper tabs and closures. It is also blow-molded in rigid packaging in order to produce crates, bottles, and pots; consumer goods including translucent parts, housewares, furniture, appliances, luggage and toys; automotive applications such battery cases and trays, air ducts, shields and deflectors, bumpers, fender liners, interior trim, instrumental panels and door trims; fibers and fabrics such raffia/ slit-film, tape, strapping, bulk continuous filament, staple fibers, spun bond and continuous filament. PP rope and twine are extraordinarily strong and moisture-resistant, being very suitable for marine applications. It is also appropriate for medical applications due to high chemical and bacterial resistance. Lastly, due to its high tensile strength, resistance to high temperatures and corrosion resistance, PP is widely used in industrial applications to produce acid and chemical tanks, sheets, pipes, returnable transport packaging and other products.
PBAT is one such potential copolymer, which is a successful alternative for low-density polyethylene in applications such as plastic film for food packaging, compostable plastic bags for gardening and agricultural use and coatings for materials such as paper cups.
PBS results in materials that are not only biodegradable and eco-friendly but also possess desirable mechanical properties, making them suitable for a wide range of applications across various industries such as packaging materials, automotive components, construction materials, agricultural mulch films, textiles and apparel, consumer goods such as disposable cutlery, tableware, and household items, furniture, eco- friendly toys, and sporting goods.
In an embodiment, the process described above may be automated, and controlled via a computer- implemented process control system as shown in FIG. 4D. Such a process control system may include sensors and measurement tools to measure the hemp particles in one or more processing stages as described above. Such a system may also be used to optimize the processing and/or formulation of the hemp particles with one or more thermoplastics or other additives to produce mold pellets for desired properties of an identified use case for a molded product. In another embodiment, the process control system may also obtain various measurements from tests of hemp plastic composite products to confirm that a formulation resulted in desirable properties for the molded product. These tests may include but are not limited to:
Tensile Testing: This measures a material's resistance to a force pulling it apart. It assesses properties like tensile strength, elongation at break, and Young's modulus, which indicate how much a hemp plastic composite can stretch before breaking and its stiffness.
Flexural Testing: This evaluates a hemp plastic composite's ability to bend without breaking. The most common method is the three-point bend test, which measures properties like flexural strength and modulus of elasticity.
Impact Testing: This determines a hemp plastic composite's ability to absorb energy when struck by a falling weight. The Charpy and Izod tests are common methods to measure impact strength.
Hardness Testing: Hardness is a measure of a material's resistance to indentation or scratching. Common methods include Rockwell, Brinell, and Vickers hardness tests.
Density Measurement: Determining a hemp plastic composite's density is essential for quality control. It can be measured using methods such as the displacement method or pycnometer.
Melt Flow Index (MFI): MFI measures the flowability of molten hemp plastic composite under specific conditions. It's particularly relevant for injection molding processes.
Thermal Analysis: Techniques like Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) assess a hemp plastic composite's thermal properties, including melting point, glass transition temperature, and decomposition temperature.
Chemical Resistance Testing: Hemp plastic composites may be exposed to various chemicals in their applications. Testing for resistance to specific chemicals may be essential to ensure product durability.
Environmental Testing: Hemp plastic composites may be subjected to UV radiation, humidity, and temperature variations. Environmental testing evaluates how these factors affect the material over time. Dimensional Measurements: Precise measurements of the product's dimensions, such as thickness and length, may be critical to ensure that a part meets design specifications.
Flammability Testing: Assessing a hemp plastic composite's resistance to combustion for safety. Common tests include the UL 94 vertical bum test and oxygen index testing.
Electrical Properties Testing: For applications involving electrical conductivity or insulation, tests like dielectric strength and surface resistivity may be important.
Based on measurements from one or more tests as described above, if the desired properties were not achieved, the process control system is configured to modify the hemp plastic composite formulation to determine a more appropriate mixture of the hemp particles with one or more thermoplastics.
In another embodiment, the process control system may be assisted by an artificial intelligence (Al) / machine learning (ML) engine, embodied and executed on a computing device (e.g. as described below with reference to FIG. 6), to retain information about various different formulations of hemp particles and one or more thermoplastics, and utilize test data obtained from one or more tests as described above to provide feedback on how well a particular hemp plastic composite formulation matched desired reference properties for a use case. An illustrative system incorporating an Al / ML engine is shown in FIG. 4D.
The feedback from the one or more tests as collected by sensors is provided as input data to the Al / ML engine, which may be one or more of text, images, sensor data, etc. The test data may undergo preprocessing steps, such as cleaning, normalization, or feature extraction, as necessary for preparing the input data for analysis.
In an embodiment, the Al / ML engine may comprise a neural network which processes and compares the test data against a desired set of parameters, and determines how successfully a hemp plastic composite formulation met the desired set of parameters. Over many iterations, a model is developed which minimizes the difference between the test data and the desired set of parameters, and the developed model is used to predict the probability that a particular hemp plastic composite formulation, or some change thereof, will result in a moulded product with the desired set of parameters or reference points.
Advantageously, over many iterations, the Al / ML engine may learn how changing the hemp particles and thermoplastics formulation and altering any parameters during the moulding process changes the characteristics of the molded parts, as measurable by one or more sensors for executing and measuring one or more of the above tests. By iteratively improving the resulting characteristics of the molded products, the trained model of the Al / ML engine is better able to recommend to the process control system a particular hemp plastic composite formulation and moulding process parameters for a particular use case.
As an illustrative example, with reference to FIG. 5A, the potential for using natural fibers as a reinforcement in composites is hampered due to the inherent incompatibility between hydrophilic fibers and the hydrophobic polymeric matrix resulting in poor fiber adhesion to the matrix. The presence of 0.5% coupling agent, polypropylene grafted with maleic anhydride (MAH), has been shown to increase the compatibility between the polypropylene matrix and the fiber, resulting in a better reinforcement mechanism.
Hemp fibers from different parts of the process were considered in this invention: Hemp Hurd (fiber length between 2 to 4 cm), Tornado Pulper (TP), Twin Flow Refiner (TFR), Atmospheric Refiner (ATM), and Masuko Refiner (MR). In all these 0.5% compatibilizers were used with the exception of TP w/o MAH (without maleic anhydride compatibilizer).
FIG. 5B shows an illustrative Flexural modulus of the hemp fiber filled PBAT composites in accordance with an illustrative embodiment.
The measurement of flexural modulus of composites made with different fiber sizes shows that there are significant differences of flexural modulus among different composites, especially between the composites made with fibers which have the smallest size. When the hemp fibers of the MR- 10% and MR-20% process were used, it showed an increase in the flexural modulus of 301 % and 679 %, respectively.
FIG. 5C shows an illustrative Flexural modulus of the hemp fiber filled PBS composites in accordance with an illustrative embodiment.
The addition of hemp fiber significantly increased the flexural modulus and tensile modulus of the samples. The flexural modulus increased from 802.89 MPa to 1524.63 MPa with the addition of 20% hemp fiber when comparing the pure polybutylene succinate sample with the TFR sample, representing an increase of 89.89%. The incorporation of fiber into matrix results in reduction in impact strength as fiber tends to hinder deformation and ductile mobility of polymer molecules which reduce the capability of composites to absorb energy during crack propagation.
Now referring to FIG. 6 shown is a schematic block diagram of a generic computing device that may provide a suitable operating environment in one or more embodiments. A suitably configured computer device, and associated communications networks, devices, software, and firmware may provide a platform for enabling one or more embodiments as described above. By way of example, FIG. 6 shows a generic computer device 700 that may include a central processing unit ("CPU") 702 connected to a storage unit 704 and to a random-access memory 706. The CPU 702 may process an operating system 701, application program 703, and data 723. The operating system 701, application program 703, and data 723 may be stored in storage unit 704 and loaded into memory 706, as may be required. Computer device 700 may further include a graphics processing unit (GPU) 722 which is operatively connected to CPU 702 and to memory 706 to offload intensive image processing calculations from CPU 702 and run these calculations in parallel with CPU 702. An operator 710 may interact with the computer device 700 using a video display 708 connected by a video interface 705, and various input/output devices such as a keyboard 710, pointer 712, and storage 714 connected by an I/O interface 709. In known manner, the pointer 712 may be configured to control movement of a cursor or pointer icon in the video display 708, and to operate various graphical user interface (GUI) controls appearing in the video display 708. The computer device 700 may form part of a network via a network interface 711, allowing the computer device 700 to communicate with other suitably configured data processing systems or circuits. A non-transitory medium 716 may be used to store executable code embodying one or more embodiments of the present method on the generic computing device 700.
Thus, in an aspect, there is provided a process to create a plastic compound with lower environmental footprint.
In an embodiment, hemp hurd is mechanically processed to decrease its particle size using mechanical refiners, creating fiber and particles that have CSF less than 300 ml. This formulation of plastic and hemp has improved mechanical performance and other desirable properties compared to the pure plastics and is therefore suitable for various use cases for molded products.
In another embodiment, there is provided a method of producing a mouldable hemp plastic composite, comprising: sourcing hemp hurd; utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired Canadian standard freeness (CSF) measurement; and formulating a composite plastic comprising a combination of the hemp particles and one or more thermoplastics.
In another embodiment, the method further comprises identifying a use case for a molded product; and formulating the composite plastic comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product. In another embodiment, the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
In another embodiment, the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, and insulation properties.
In another aspect, there is provided a method of producing a mouldable hemp plastic composite, comprising: i) sourcing hemp hurd; ii) processing the hemp hurd utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired freeness measurement; and iii) formulating a hemp plastic composite comprising a combination of hemp particles processed in step ii) with one or more thermoplastics.
In an embodiment, the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
In another embodiment, the hemp hurd is sourced from a Cannabis sativa plant.
In another embodiment, the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
In another embodiment, the method further comprises processing a mixture of hemp particles and one ore more thermoplastics between 100 °C to 230 °C.
In another embodiment, the method further comprises: a) identifying a use case for a molded product; and b) formulating the composite plastic comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product.
In another embodiment, the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
In another embodiment, the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, dimensional conformity, thermal properties, chemical properties, and electrical properties.
In another aspect, there is provided a process control system adapted to control a process for performing the method in accordance with claim 1. In an embodiment, the process control system receives feedback from test measurements comprising one or more of tensile testing, flexural testing, impact testing, hardness testing, density measurement, melt flow index, thermal analysis, chemical resistance, environmental testing, dimensional measurements, flammability testing, and electrical properties testing.
In another embodiment, the system incorporates an artificial intelligence (Al) / machine learning (ML) engine which may be trained on feedback from the test measurements to determine which hemp plastic composite formulations result in the desirable properties for one or more use cases.
In another embodiment, the AI/ML engine is adapted to recommend a hemp plastic composite formulation for a given use case.
In another embodiment, the AI/ML engine is further adapted to guide the process control system to control the proportion of hemp particles to one or more thermoplastics.
In another embodiment, the AI/ML engine is further adapted to guide the process control system to control the proportion of hemp particles, one or more thermoplastics, and one or more additives to achieve desirable properties for one or more use cases.
In another embodiment, the AI/ML engine is further adapted to recommend control settings for the mixing process, the mixing temperature, and the subsequent moulding process.
In another aspect, there is provided a mouldable hemp plastic composite formulation, comprising: a) hemp particles sourced from the hemp hurd, the hemp particles having a desired freeness measurement; and b) one or more thermoplastics.
In an embodiment, the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
In another embodiment, the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
In another embodiment, the mouldable hemp plastic composite formulation further comprises one or more additives to achieve desirable properties for one or more use cases.
In another embodiment, the hemp hurd is sourced from a Cannabis sativa plant. While various illustrative embodiments of the system, method, and apparatus have been described, it will be appreciated that various modifications and amendments may be made without departing from the scope of the invention.

Claims

CLAIMS:
1. A method of producing a mouldable hemp plastic composite, comprising: i) sourcing hemp hurd; ii) processing the hemp hurd utilizing a mechanical refiner to create hemp particles from the hemp hurd, the hemp particles having a desired freeness measurement; and iii) formulating a hemp plastic composite comprising a combination of hemp particles processed in step ii) with one or more thermoplastics.
2. The method of claim 1, wherein the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
3. The method of clam 1, wherein the hemp hurd is sourced from a Cannabis sativa plant.
4. The method of claim 1, wherein the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
5. The method of claim 1, further comprising processing amixture of hemp particles and one or more thermoplastics between 100 °C to 230 °C.
6. The method of claim 1, further comprising: a) identifying a use case for a molded product; and b) formulating the composite plastic comprising a combination of the hemp particles and one or more thermoplastics such that the formulation is suitable for the identified use case for the molded product.
7. The method of claim 6, wherein the formulation suitable for the identified use case is selected to have properties desirable for the molded product.
8. The method of claim 7, wherein the desirable properties include one or more of mechanical strength, impact resistance, wear resistance, deformability, dimensional conformity, thermal properties, chemical properties, and electrical properties.
9. A process control system adapted to control a process for performing the method in accordance with claim 1.
10. The process control system of claim 9, wherein the process control system receives feedback from test measurements comprising one or more of tensile testing, flexural testing, impact testing, hardness testing, density measurement, melt flow index, thermal analysis, chemical resistance, environmental testing, dimensional measurements, flammability testing, and electrical properties testing.
11. The process control system of claim 10, wherein the system incorporates an artificial intelligence (Al) / machine learning (ML) engine which may be trained on feedback from the test measurements to determine which hemp plastic composite formulations result in the desirable properties for one or more use cases.
12. The process control system of claim 11, wherein the AI/ML engine is adapted to recommend a hemp plastic composite formulation for a given use case.
13. The process control system of claim 12, wherein the AI/ML engine is further adapted to guide the process control system to control the proportion of hemp particles to one or more thermoplastics.
14. The process control system of claim 12, wherein the AI/ML engine is further adapted to guide the process control system to control the proportion of hemp particles, one or more thermoplastics, and one or more additives to achieve desirable properties for one or more use cases.
15. The process control system of claim 14, wherein the AI/ML engine is further adapted to recommend settings for the control the mixing process, the mixing temperature, and the subsequent moulding process.
16. A mouldable hemp plastic composite formulation, comprising: a) hemp particles sourced from the hemp hurd, the hemp particles having a desired freeness measurement; and b) one or more thermoplastics.
17. The mouldable hemp plastic composite formulation of claim 16, wherein the hemp particles have a Canadian standard freeness (CSF) of less than 300 ml.
18. The mouldable hemp plastic composite formulation of claim 16, wherein the amount of hemp particles in the hemp plastic composite is in the range of 5 to 50% by weight.
19. The mouldable hemp plastic composite formulation of claim 16, further comprising one or more additives to achieve desirable properties for one or more use cases.
20. The mouldable hemp plastic composite formulation of claim 16, wherein the hemp hurd is sourced from a Cannabis sativa plant.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1318067C (en) * 1987-06-26 1993-05-18 Fumio Goto Composite thermoplastic materials reinforced with hemp fibers
KR20110088801A (en) * 2010-01-29 2011-08-04 한중대학교 산학협력단 Plastics containing hemp as a main ingredient and methods for preparing the same
US11149131B2 (en) * 2020-01-30 2021-10-19 Edward Showalter Earth plant compostable biodegradable substrate and method of producing the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1318067C (en) * 1987-06-26 1993-05-18 Fumio Goto Composite thermoplastic materials reinforced with hemp fibers
KR20110088801A (en) * 2010-01-29 2011-08-04 한중대학교 산학협력단 Plastics containing hemp as a main ingredient and methods for preparing the same
US11149131B2 (en) * 2020-01-30 2021-10-19 Edward Showalter Earth plant compostable biodegradable substrate and method of producing the same

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