CN105622991B - Nano micro crystal cellulose enhances the preparation method of chitosan/guar gum composite membrane - Google Patents

Abstract

The invention discloses a preparation method of a nano-microcrystalline cellulose reinforced chitosan/guar gum composite film. The invention first prepares chitosan solution and guar gum solution, and mixes chitosan solution and guar gum solution according to a certain volume ratio to obtain uniformly mixed chitosan/guar gum solution. Secondly, prepare nano-microcrystalline cellulose suspension with microcrystalline cellulose powder, and then prepare nano-microcrystalline cellulose suspension; add nano-microcrystalline cellulose suspension of different proportions to chitosan/guar gum and mix In the solution, a high-speed disperser is used to disperse and ultrasonicate to obtain a chitosan/guar gum/nano microcrystalline cellulose mixed solution. Finally, take a certain amount of chitosan/guar gum/nano-microcrystalline cellulose mixed solution and cast it on an acrylic plate, and dry it in a blast drying oven at a constant temperature to obtain chitosan/guar gum/nano-microcrystalline fiber plain composite film. The invention mixes the natural macromolecule and the synthetic macromolecule, and endows the mixture with excellent comprehensive performance.

Description

Preparation method of nano-microcrystalline cellulose reinforced chitosan/guar gum composite film

technical field

The invention relates to the field of composite membrane materials, in particular to a method for preparing a nano-microcrystalline cellulose reinforced chitosan/guar gum composite membrane to produce a non-toxic, biodegradable, high-performance, environment-friendly composite membrane.

Background technique

Chitosan (chitosan) is obtained by deacetylation of chitin (chitin), which exists widely in nature. It is insoluble in water and alkaline solution, but soluble in dilute acid with pH<6.5. It is non-toxic, odorless, slightly Sweet white powder, molecular formula (C ₆ H ₁₁ NO ₄ ) _n , molecular weight (160.9) _n , pH value 7.0-8.0, viscosity 50-800 mPa·s. Chitosan has good gas permeability, film-forming property, blood compatibility, safety and microbial degradability, so it is widely used in many fields such as medicine, food, chemical industry, cosmetics, water treatment, biomedical engineering and so on. Guar gum (Guargum) is a galactomannan with a content of 98%, soluble in cold and hot water, insoluble in oils, fats, hydrocarbons, ketones and esters. The aqueous solution is a tasteless, odorless, non-toxic, neutral, light gray transparent liquid, which is highly viscous in water, and the viscosity changes depend on the particle size, pH, temperature, etc. Guar gum can be used as emulsification stabilizer and thickener, as well as conditioner, antistatic agent and thickener for hair and skin.

The composite film of chitosan and guar gum is non-toxic, has good antibacterial properties and biocompatibility, is a biodegradable and environmentally friendly composite film, can effectively reduce environmental problems, and is expected to be used in food packaging field.

Nanocrystalline cellulose (NCC) is a kind of cellulose crystal obtained by extracting the amorphous region and the low-crystallinity crystalline region of cellulose by certain treatment of cellulose. NCC is approximately rod-shaped, with a diameter of about 30-80nm and a length of about 300-600nm. Nano-microcrystalline cellulose has excellent mechanical properties, huge specific surface area (~70), high crystallinity (>70%), and high Young's modulus , high strength (7500MPa), ultra-fine structure and high transparency, good biodegradability and biocompatibility, and stable chemical properties. In view of its unique physical and chemical properties, it has strong application potential in the fields of fine chemicals, medicine, food, ultra-micro composite materials, heat exchange materials and new energy. Therefore, the research and development of nano-microcrystalline cellulose has important scientific significance and application value.

The strong polarity and large specific surface area of nanocrystalline cellulose make it have a strong interaction with water, and it is easy to form a entangled network structure, so that the solution has a gel-like behavior, enhances the flow resistance of the solution, and increases the flow resistance of the solution. Therefore, adding nanocrystalline cellulose to the chitosan/guar gum mixed system can significantly enhance the viscosity. Research and development of related preparation technology to produce a chitosan/guar gum/nanocrystalline cellulose composite film has important practical value and environmental protection value.

Contents of the invention

Based on the strengthening effect of nano-microcrystalline cellulose, the purpose of this invention is to provide a kind of preparation method of nano-microcrystalline cellulose reinforced chitosan/guar gum composite film, which can produce non-toxic, good biocompatibility, biodegradable The degradable environment-friendly composite film, which reduces environmental problems, is also expected to provide a new method for the field of food packaging.

The purpose of the present invention is achieved through the following technical solutions:

(1) First, prepare a certain concentration of chitosan solution and guar gum solution, and mix the chitosan solution and guar gum solution according to a certain volume ratio to obtain a uniformly mixed chitosan/guar gum solution.

(2) Secondly, use the method of acid hydrolysis to prepare nanocrystalline cellulose suspension with microcrystalline cellulose powder, and then prepare nanocrystalline cellulose suspension with a certain solid content; nanocrystalline cellulose with different proportions The suspension is added to the chitosan/guar gum mixed solution, dispersed and ultrasonicated by a high-speed disperser to obtain the chitosan/guar gum/nano-microcrystalline cellulose mixed solution.

(3) Finally, take a certain amount of chitosan/guar gum/nano-microcrystalline cellulose mixed solution and cast it on an acrylic plate, and dry it in a blast drying oven at a constant temperature to obtain chitosan/guar gum/ Nano-microcrystalline cellulose composite film, and the composite film is placed in a ziplock bag for preservation.

Chitosan/guar gum/nano-microcrystalline cellulose composite membrane obtains through following process in this implementation step:

① Accurately weigh 1g of chitosan powder and dissolve it in 100mL of 2% (v/v) acetic acid solution, shake and accelerate the dissolution in a constant temperature water bath at 90°C to obtain a uniformly mixed 1% (w/v) chitosan solution ; Accurately weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, heat and stir to dissolve, and obtain a uniformly mixed 1% (w/v) guar gum solution.

② Take 15mL guar gum solution and add it to 85mL chitosan solution (do not add it in reverse, otherwise the mixed solution will turn light red after heating for a period of time, which will lead to the failure of the experiment), and then put the mixed solution of chitosan and guar gum in the In a constant temperature water bath at 90°C, the stirring speed of the digital heating magnetic stirrer is controlled at 400r/min, and mixed for 2-3 hours to obtain a uniform and transparent chitosan/guar gum mixed solution.

③The nano-microcrystalline cellulose suspension obtained by acid hydrolysis is diluted with water to prepare a solid content of 1% (w/w), and then according to the ratio of 0%, 1%, 3%, 5% or 7% (nano-microcrystalline cellulose The solid content of the crystalline cellulose suspension (relative to the solid content of the chitosan/guar gum mixed solution) is added to the chitosan/guar gum mixed solution, the speed of the high-speed disperser is 1000-2000r/min, and the dispersion is 30-60min , ultrasonic 30min, to obtain chitosan/guar gum/nanocrystalline cellulose mixed solution.

④ Take 50g of chitosan/guar gum/nano-microcrystalline cellulose mixed solution and cast it on a special 130mm×18mm×3mm acrylic plate mold, put it in a blast drying oven at a constant temperature of 50°C and dry it for 5 hours to obtain chitosan Sugar/guar gum/nanocrystalline cellulose composite film.

Beneficial effects of the present invention:

(1) The present invention combines chitosan's good film-forming properties, air permeability and excellent physical and chemical properties of guar gum, and at the same time adds nano-microcrystalline cellulose, which can play a reinforcing role, to prepare a composite material with excellent mechanical properties. membrane.

(2) In the present invention, a digital display heating magnetic stirrer and a high-speed dispersing machine are used to make the mixed solution reach a state of uniform dispersion at a certain speed and a certain time, breaking through the chitosan solution, guar gum solution, nano micro The difficult problem that crystalline cellulose suspensions are not easy to disperse.

(3) The present invention mixes natural macromolecules and synthetic macromolecules, endows the mixture with excellent comprehensive properties, uses non-toxic, biocompatible chemical reagents, and prepares biodegradable and environment-friendly composite Films are expected to be used in food packaging materials.

Detailed ways

The present invention will be further described below in conjunction with the examples, but the protection scope of the present invention is not limited to the scope expressed by the examples. Unless otherwise indicated.

Example 1:

First, weigh 1g of chitosan powder and dissolve it in 100mL of 2% (v/v) acetic acid solution, stir in a constant temperature water bath at 90°C to accelerate the dissolution, and obtain a uniformly mixed 1% (w/v) chitosan solution Weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, stir in a beaker to accelerate dissolution, and obtain a uniformly mixed 1% (w/v) guar gum solution; then mix the uniformly mixed chitosan solution with guar gum The solution was added into a three-necked flask at a volume ratio of 85:15, placed in a constant temperature water bath at 90°C, and stirred at a stirring speed of 400r/min for 2h to obtain a uniformly mixed and transparent chitosan/guar gum solution. Finally, take 50g of the homogeneously mixed transparent chitosan/guar gum solution and cast it on a special 130mm×18mm×3mm acrylic plate, place it in a blast drying oven at a constant temperature of 50°C and dry it for 5 hours to obtain a transparent chitosan Sugar/Guar Gum Composite Film.

Example 2:

First, weigh 1g of chitosan powder and dissolve it in 100mL of 2% (v/v) acetic acid solution, stir in a constant temperature water bath at 90°C to accelerate the dissolution, and obtain a uniformly mixed 1% (w/v) chitosan solution Weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, stir in a beaker to accelerate dissolution, and obtain a uniformly mixed 1% (w/v) guar gum solution; then mix the uniformly mixed chitosan solution with guar gum The solution was added into a three-necked flask at a volume ratio of 85:15, placed in a constant temperature water bath at 90°C, and stirred at a stirring speed of 400r/min for 2h to obtain a uniformly mixed and transparent chitosan/guar gum solution. Then, add the nano-microcrystalline cellulose suspension (1%, w/w) to the homogeneously mixed transparent chitosan/guar gum mixed solution according to the ratio of 1%, and use a high-speed disperser under the condition of 1000rpm Disperse for 60 minutes, and then sonicate for 30 minutes to obtain a uniform transparent chitosan/guar gum/nanocrystalline cellulose solution. Finally, take 50g of the homogeneously mixed transparent chitosan/guar gum/nano-microcrystalline cellulose solution and cast it on an acrylic plate (130mm×18mm×3mm), and place it in a blast drying oven at a constant temperature of 50°C for 5 hours to dry , to obtain a transparent chitosan/guar gum/nano-microcrystalline cellulose composite film.

Example 3:

First, weigh 1g of chitosan powder and dissolve it in 100mL of 2% (v/v) acetic acid solution, stir in a constant temperature water bath at 90°C to accelerate the dissolution, and obtain a uniformly mixed 1% (w/v) chitosan solution Weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, stir in a beaker to accelerate dissolution, and obtain a uniformly mixed 1% (w/v) guar gum solution; then mix the uniformly transparent chitosan solution with guar The guar gum solution was added into a three-necked flask at a volume ratio of 85:15, placed in a constant temperature water bath at 90°C, and stirred at a stirring speed of 400r/min for 2h to obtain a uniformly mixed and transparent chitosan/guar gum solution. Then, add the nano-microcrystalline cellulose suspension (1%, w/w) to the homogeneously mixed transparent chitosan/guar gum mixed solution according to the ratio of 3%, and use a high-speed disperser under the condition of 1000rpm Disperse for 60 minutes and sonicate for 30 minutes to obtain a uniform transparent chitosan/guar gum/nanocrystalline cellulose solution. Finally, take 50g of a homogeneously mixed transparent chitosan/guar gum/nanocrystalline cellulose solution and cast it on an acrylic plate (130mm×18mm×3mm), place it in an oven at a constant temperature of 50°C for 5 hours and dry it to obtain a transparent chitosan/guar gum/nanocrystalline cellulose composite film.

Example 4:

First, weigh 1g of chitosan powder and dissolve it in 100mL of 2% (v/v) acetic acid solution, stir in a constant temperature water bath at 90°C to accelerate the dissolution, and obtain a uniformly mixed 1% (w/v) chitosan solution Weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, stir in a beaker to accelerate dissolution, and obtain a uniformly mixed 1% (w/v) guar gum solution; then mix the uniformly mixed chitosan solution with guar gum The solution was added into a three-necked flask at a volume ratio of 85:15, placed in a constant temperature water bath at 90°C, and stirred at a stirring speed of 400r/min for 2h to obtain a uniformly mixed and transparent chitosan/guar gum solution. Then, according to the ratio of 5%, nanocrystalline cellulose suspension (1%, w/w) was added to the homogeneously mixed chitosan/guar gum mixed solution, and a high-speed disperser was used to disperse at 1000rpm for 60min , Ultrasound for 30min to obtain a uniform transparent chitosan/guar gum/nanocrystalline cellulose solution. Finally, take 50g of the homogeneously mixed transparent chitosan/guar gum/nano-microcrystalline cellulose solution and cast it on an acrylic plate (130mm×18mm×3mm), and place it flat in a blast drying oven at a constant temperature of 50°C for 5 hours to dry , to obtain a transparent chitosan/guar gum/nano-microcrystalline cellulose composite film.

Example 5:

First, weigh 1g of chitosan powder and dissolve it in 100mL of 2% (v/v) acetic acid solution, stir in a constant temperature water bath at 90°C to accelerate the dissolution, and obtain a uniformly mixed 1% (w/v) chitosan solution Weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, stir in a beaker to accelerate dissolution, and obtain a uniformly mixed 1% (w/v) guar gum solution; then mix the uniformly mixed chitosan solution with guar gum The solution was added into a three-necked flask at a volume ratio of 85:15, placed in a constant temperature water bath at 90°C, and stirred at a stirring speed of 400r/min for 2h to obtain a uniformly mixed and transparent chitosan/guar gum solution. Then, add nanocrystalline cellulose suspension (1%, w/w) to the homogeneously mixed chitosan/guar gum mixed solution according to the proportion of 7%, and disperse for 60min under the condition of 1000rpm with a high-speed disperser , Ultrasound for 30min to obtain a uniform transparent chitosan/guar gum/nanocrystalline cellulose solution. Finally, take 50g of the homogeneously mixed transparent chitosan/guar gum/nano-microcrystalline cellulose solution and cast it on an acrylic plate (130mm×18mm×3mm), and place it flat in a blast drying oven at a constant temperature of 50°C for 5 hours to dry , to obtain a transparent chitosan/guar gum/nano-microcrystalline cellulose composite film.

Claims (4)

1. The preparation method of nano-microcrystalline cellulose reinforced chitosan/guar gum composite film, concrete steps are as follows: Step (1) Prepare a certain concentration of chitosan solution and guar gum solution, and add the guar gum solution into the chitosan solution according to a certain volume ratio for mixing to obtain a uniformly mixed chitosan/guar gum solution. Step (2) Prepare nano-microcrystalline cellulose suspension with microcrystalline cellulose powder by acid hydrolysis, and then prepare nano-microcrystalline cellulose suspension with a certain solid content, and suspend nano-microcrystalline cellulose with different proportions Add liquid to the chitosan/guar gum mixed solution obtained in step (1), disperse with a high-speed disperser, and then sonicate to obtain a chitosan/guar gum/nanocrystalline cellulose mixed solution; Step (3) Take a certain amount of chitosan/guar gum/nano-microcrystalline cellulose mixed solution obtained in step (2) and cast it on an acrylic plate, and dry it in a blast drying oven at a constant temperature to obtain chitosan Sugar/guar gum/nano-microcrystalline cellulose composite film; In the step (1), 1g of chitosan powder is accurately weighed and dissolved in 100mL of acetic acid solution with a volume ratio of 1-2%, shaken in a constant temperature water bath at 70°C-90°C to accelerate dissolution, and obtain a uniform weight A chitosan solution with a volume ratio of 1%; accurately weigh 1g of guar gum powder and dissolve it in 100mL of distilled water, heat and stir to dissolve, and obtain a well-mixed guar gum solution with a weight to volume ratio of 1%; In the step (1), take 15mL of guar gum solution and add it to 85mL of chitosan solution, then place the mixed solution of chitosan and guar gum in a constant temperature water bath at 70°C-90°C, and heat the digital display with magnetic stirring The stirring speed of the device is controlled at 400r/min, and the mixture is mixed for 2-3 hours to obtain a uniform and transparent chitosan/guar gum mixed solution. 2. The preparation method according to claim 1, characterized in that in step (2), the nanocrystalline cellulose suspension obtained by acid hydrolysis is diluted with water to prepare a solid content of 1% by weight, and then according to 1%, The proportion of 3%, 5% or 7% is added in the chitosan/guar gum mixed solution, and this proportion is the solid content of the nano-microcrystalline cellulose suspension relative to the solid content of the chitosan/guar gum mixed solution. content. 3. The preparation method according to claim 1, characterized in that in step (2), the speed of the high-speed disperser is 1000-2000r/min, the dispersion is 30-60min, and the ultrasonic is 30min. 4. The preparation method according to claim 1, characterized in that step (3) takes 40-60 g of the chitosan/guar gum/nano-microcrystalline cellulose mixed solution obtained in step (2) and casts it to a size of 130mm×18mm ×3mm acrylic plate mold, put it in a blast drying oven at a constant temperature of 50°C for 5-7 hours, and dry it to obtain a chitosan/guar gum/nano-microcrystalline cellulose composite film.