CN102391661B - Method for preparing polymer composite material from plant fiber by chemical non-continuous pretreatment - Google Patents

Abstract

The invention discloses a method for preparing polymer composite materials through chemical discontinuous pretreatment of plant fibers. The specific steps are: fix the plant fibers whose length has been cut to 2cm to 3cm with a clamp, and adjust the height of the clamp to infiltrate part of the plant fibers into the chemical In the pretreatment reagent, the discontinuously pretreated plant fiber is obtained by washing; then the discontinuously pretreated plant fiber is mixed with the dried matrix resin to obtain a composite material; then the composite material is hot-pressed, Deburring, flashing, made of composite products. In the present invention, the composition and structure of the fiber part treated by the chemical reagent changes due to the action of the reagent, and fibrillation occurs, the interface adhesion between the plant fiber and the matrix material is strengthened, and the fiber part that is not infiltrated by the chemical reagent maintains the original fibril. There is strength. Compared with the composite material prepared with completely treated fibers of the same kind, the method of the invention can further enhance the mechanical properties of the prepared composite material.

Description

Method for preparing polymer composite material by chemical discontinuous pretreatment of plant fiber

technical field

The invention relates to a method for improving the interface adhesion between the plant fiber and the polymer matrix while maintaining the mechanical properties of the plant fiber through discontinuous chemical pretreatment, in particular to the preparation of polymer composite materials by chemical discontinuous pretreatment of plant fiber Methods.

Background technique

With the enhancement of people's awareness of environmental protection, the research and development of plant fiber reinforced polymer matrix composites has become a research hotspot in the new century. However, due to the high interfacial tension between the plant fiber and the matrix material, the matrix material has poor wettability to the plant fiber during melting, and the interface adhesion of the composite material is weak, which affects the mechanical properties of the composite material. Therefore, chemical or physical methods must be used for surface pretreatment of plant fibers.

Traditional chemical pretreatment methods include alkali treatment, grafting treatment, coupling treatment, etc., but no matter which method is used, the specific implementation process is to completely soak the fiber to strengthen the bond between the plant fiber and the polymer matrix. interface performance. However, such a complete immersion treatment method will weaken the performance of the plant fiber itself to a large extent. For composite materials, the improvement of the interfacial strength is only meaningful if the weakening of the properties of the plant fiber itself by a method does not affect the overall performance of the composite material. Most of the current scholars focus on the adjustment of the formulation or process parameters of the specific treatment method, such as the adjustment of the solvent concentration, the change of the treatment time, or the use of some new treatment reagents, and have not considered the adjustment of the reagents. How to improve the specific embodiment of plant fiber, all adopt the treatment method of soaking completely.

Contents of the invention

In order to solve the above defects and deficiencies in the prior art, the object of the present invention is to provide a method for preparing polymer composite materials through chemical discontinuous pretreatment of plant fibers.

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

(1) Fix the plant fiber that has been cut to a length of 2cm-3cm with a fixture, adjust the height of the fixture so that 1/5-4/5 of the length of the plant fiber is soaked in the chemical pretreatment reagent, the soaking time is 10min-120min, and then washed Plant fibers after infiltration until the washing waste liquid is neutral, that is, discontinuously pretreated plant fibers are obtained;

After the above chemical discontinuous pretreatment, the part of the plant fiber soaked in the chemical pretreatment reagent removes impurities such as hemicellulose, lignin, pectin, and increases the contact area between the plant fiber and the matrix material and the number of reactive groups. Accessibility, reducing the microfiber rotation angle, improving the interface properties between plant fibers and matrix materials; the part that is not infiltrated into the chemical pretreatment reagent maintains the original mechanical properties of plant fibers, thereby improving the comprehensive performance of composite materials. The effect of mechanical strength.

(2) Put discontinuously pretreated plant fibers and dried matrix resin into the mixing equipment for mixing, and the mixing temperature is 175°C to 210°C; discontinuously pretreated plant fibers account for 10% of the mass of dried matrix resin % to 50%, and the mixing time is 5 min to 10 min to obtain composite materials;

(3) The above-mentioned composite material is hot-pressed to obtain a molded product, and then deburred and flashed to obtain a composite material product.

The chemical pretreatment reagent is lye, grafting reagent or coupling reagent.

The lye is a NaOH solution or KOH solution with a mass concentration of 5% to 20%; the grafting reagent is an alkylating reagent, an acetylating reagent, a benzoylating reagent or a cyanoethylating reagent; The coupling agent is a silane coupling agent, titanate coupling agent, organic chromium complex coupling agent or alumina acid coupling agent with a mass concentration of 0.5% to 2%.

The plant fiber is a phloem fiber of more than one fiber in flax, hemp, jute, ramie, kenaf and sisal, or a braid of the above-mentioned phloem fiber.

The temperature of the hot press forming is 190°C-210°C, the pressure is 8Mpa-12Mpa, and the molding time is 15min-22min; during the hot-pressing process, deflate 20-40 times, and the interval between each deflate is 2s-3s .

The chemical discontinuous pretreatment of plant fibers in the present invention can be used as a separate step in the preparation process of various plant fiber reinforced macromolecule matrix composite materials. The plant fibers treated by the present invention can be used to prepare composite materials by various existing mixing and forming processes such as open refining, banburying, extrusion, and calendering. Problems at the expense of improving composite interfacial properties. The plant fiber of the present invention is not limited to sisal fiber, because the core of the present invention is that when the plant fiber is pretreated, the sisal fiber that is not soaked in the chemical reagent remains in its original state and maintains the original good mechanical properties of the fiber. Various plant fibers that use plant fibers to reinforce polymer matrix composites, such as flax, hemp, jute, ramie or kenaf bast fibers, have similar properties to sisal fibers.

Compared with the prior art, the present invention has the following advantages:

(1) The present invention carries out discontinuous pretreatment to plant fibers, so that the part treated by the pretreatment solution and the untreated part exist in a bundle of plant fibers at the same time, and the treated part removes hemicellulose, lignin, Pectin and other impurities, the interface binding force with the matrix material has been enhanced, and the properties of the untreated part of the plant fiber will not be weakened. While enhancing the interface properties of the plant fiber and the matrix material, it reduces the impact of the pretreatment process on the properties of the plant fiber itself. The damage of the plant fiber can be made to maximize the reinforcement performance when it is combined with the matrix material;

(2) The plant fibers pretreated by the present invention can be used to prepare composite materials by various existing mixing and forming processes such as kneading, banburying, extrusion, and calendering. The process route is simple and feasible, and is suitable for industrial production.

Description of drawings

Fig. 1 is a schematic diagram of plant fiber pretreatment in the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments and accompanying drawings, but is not limited thereto.

The schematic diagram of the operation of chemical discontinuous pretreatment of plant fibers is shown in Figure 1, in which 1 is an iron stand, 2 is a water tank, 3 is a fixture, 4 is a plant fiber, and 5 is a chemical pretreatment reagent.

1. Put the NaOH alkali treatment solution with a mass concentration of 18% in the water tank. Fix a bunch of sisal fibers that have been cut to 2cm in length on the iron stand with clamps, adjust the height of the clamps so that 1/2 of the plant fibers are immersed below the liquid level of the tank, and the remaining 1/2 is exposed to the air. The treatment time is 10 minutes . Then wash the treated plant fiber until the washing waste liquid is neutral, and then a non-continuously pretreated plant fiber with one end treated by solution and the other end untreated can be obtained;

2. Add the above discontinuously pretreated plant fibers and the dried matrix resin polylactic acid into an open mill for mixing, the discontinuously pretreated plant fibers account for 20% of the dried matrix resin mass, and the mixing temperature is 175 ℃, the mixing time is 10min, and the composite material is obtained;

3. Add the composite material prepared in the above steps into a mold, specifically a rectangular plate mold with a length, width, and thickness of 20cm, 10cm, and 4mm, respectively, and heat-press it on a flat vulcanizing machine. The molding temperature is 210°C, the pressure is 10Mpa, and the molding time is 15min. During the hot pressing process, deflate 20 times, and the interval between each deflation is 3s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

Example 2

1. Put the NaOH alkali treatment solution with a mass concentration of 18% in the water tank. Set a bundle of sisal fibers cut to 2cm in length on the iron stand with a jig, adjust the height of the jig so that 1/2 of the plant fiber is immersed below the liquid level of the tank, and the remaining 1/2 is exposed to the air. The treatment time is 10 minutes . Then wash the treated plant fiber until the washing waste liquid is neutral, and then a non-continuously pretreated plant fiber with one end treated by solution and one end untreated can be obtained;

2 Add the above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid to an open mill for mixing. The discontinuously pretreated plant fibers account for 30% of the mass of the dried matrix resin, and the mixing temperature is 185 ℃, the mixing time is 8min, and the composite material is obtained;

3. Add the composite material prepared in the above steps into a mold, specifically a rectangular plate mold with a length, width, and thickness of 20cm, 10cm, and 4mm, respectively, and heat-press it on a flat vulcanizing machine. The molding temperature is 200°C, the pressure is 10Mpa, and the molding time is 19min. During the hot pressing process, deflate 30 times, and the interval between each deflation is 3s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

Example 3

1. Put the NaOH alkali treatment solution with a mass concentration of 18% in the water tank. Fix a bunch of sisal fibers that have been cut to 2cm in length on the iron stand with clamps, adjust the height of the clamps so that 1/2 of the plant fibers are immersed below the liquid level of the tank, and the remaining 1/2 is exposed to the air. The treatment time is 10 minutes . Then wash the treated plant fiber until the washing waste liquid is neutral, and then a non-continuously pretreated plant fiber with one end treated by solution and one end untreated can be obtained;

2. Add the above discontinuously pretreated plant fibers and the dried matrix resin polylactic acid into an open mill for mixing, the discontinuously pretreated plant fibers account for 40% of the mass of the dried matrix resin, and the mixing temperature is 200°C , the mixing time is 5min to obtain the composite material;

3. Add the composite material prepared in the above steps into a mold, specifically a rectangular plate mold with a length, width, and thickness of 20cm, 10cm, and 4mm, respectively, and heat-press it on a flat vulcanizing machine. The molding temperature is 190°C, the pressure is 8Mpa, and the molding time is 22min. During the hot pressing process, deflate 40 times, and the interval between each deflation is 2s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

The composite material products prepared in embodiment 1 to embodiment 3 are made into sample strips respectively (wherein the tensile sample strip size for tensile performance test is: effective length 25mm, width 4mm, thickness 1mm, dumbbell-shaped sample strip ; The sample size used for impact performance and bending performance test is: length 10cm, width 10mm, thickness 4mm, rectangular parallelepiped sample), and the sisal fiber in each embodiment is carried out fully soaking continuous pretreatment respectively, as contrast group, the pretreatment reagent and its concentration, soaking time are all the same as each corresponding embodiment, the preparation steps of each control group composite material product are all the same as each corresponding embodiment, and then carry out the performance test. Tensile performance, bending performance and impact performance were tested according to GB/T1040-2006, GB1449-2005 and GB/T1843-2008 respectively, and the test results are shown in Table 1.

Table 1

It can be seen from the above table that the mechanical properties of sisal fiber reinforced polylactic acid composites prepared by chemical discontinuous treatment with one end treated and the other untreated are generally improved. In Example 1 where the sisal fiber mass fraction is 20%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 72.54% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 39.32%; the tensile modulus increased by 12.28%. In Example 2 where the sisal fiber mass fraction is 30%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 39.46% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 53.49%; the tensile modulus increased by 13.12%. In Example 3 where the sisal fiber mass fraction is 40%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 65.79% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 15.87%; the tensile modulus increased by 12.48%.

Example 4

1. Put the NaOH lye with a mass concentration of 10% in the water tank. Fix a bundle of fibers that have been cut to 3cm on the iron stand with a clamp, adjust the height of the clamp, so that 1/3 of the fiber is immersed below the liquid level of the tank, and the remaining 2/3 is exposed to the air, and treated for 30 minutes; then the fiber is turned upside down, 1/3 of the other end is placed in the solution, and treated for the same time; then washed to neutrality, the discontinuous pretreatment plant fiber with both ends treated by solution and untreated in the middle can be obtained;

2. The above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid are added to an open mill at a weight ratio of 10:5 for mixing, and the discontinuously pretreated plant fibers account for 20% of the mass of the dried matrix resin , the mixing temperature was 175°C, and the mixing time was 10 minutes to obtain a composite material;

3. Put the composite material prepared in the above steps into the mold, specifically use a rectangular plate mold, the mold length, width, and thickness are 20cm, 10cm, and 4mm, respectively, and heat-press on a flat vulcanizing machine. The molding temperature is 210°C, the pressure is 10Mpa, and the molding time is 15min. Deflate 20 times during the hot pressing process, and the interval between each deflation is 3s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

Example 5

1. Put the NaOH lye with a mass concentration of 10% in the water tank. Fix a bundle of fibers that have been cut to 3cm on the iron stand with a clamp, adjust the height of the clamp, so that 1/3 of the fiber is immersed below the liquid level of the tank, and the remaining 2/3 is exposed to the air, and treated for 30 minutes; then the fiber is turned upside down, 1/3 of the other end is placed in the solution, and treated for the same time; then washed to neutrality, the discontinuous pretreatment plant fiber with both ends treated by solution and untreated in the middle can be obtained;

2. The above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid are added to an open mill at a weight ratio of 10:5 for mixing, and the discontinuously pretreated plant fibers account for 30% of the mass of the dried matrix resin , the mixing temperature was 185°C, and the mixing time was 8 minutes to obtain a composite material;

3. Put the composite material prepared in the above steps into the mold, specifically use a rectangular plate mold, the mold length, width, and thickness are 20cm, 10cm, and 4mm, respectively, and heat-press on a flat vulcanizing machine. The molding temperature is 200°C, the pressure is 9Mpa, and the molding time is 19min. During the hot pressing process, deflate 30 times, and the interval between each deflation is 3s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

Example 6

1. Put the NaOH lye with a mass concentration of 10% in the water tank. Fix a bundle of fibers that have been cut to 3cm on the iron stand with a clamp, adjust the height of the clamp, so that 1/3 of the fiber is immersed below the liquid level of the tank, and the remaining 2/3 is exposed to the air, and treated for 30 minutes; then the fiber is turned upside down, 1/3 of the other end is placed in the solution, and treated for the same time; then washed to neutrality, the discontinuous pretreatment plant fiber with both ends treated by solution and untreated in the middle can be obtained;

2. The above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid are added to an open mill at a weight ratio of 10:5 for mixing, and the discontinuously pretreated plant fibers account for 40% of the mass of the dried matrix resin , the mixing temperature was 200°C, and the mixing time was 5 minutes to obtain a composite material;

3. Put the composite material prepared in the above steps into the mold, specifically use a rectangular plate mold, the mold length, width, and thickness are 20cm, 10cm, and 4mm, respectively, and heat-press on a flat vulcanizing machine. The molding temperature is 190°C, the pressure is 8Mpa, and the molding time is 22min. Deflate 40 times during the hot pressing process, and the interval between each deflation is 2s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

After the composite material products made in embodiment 4 to embodiment 6 are respectively made into splines (the spline size is the same as embodiment 1-embodiment 3), and the sisal fiber in each embodiment is fully soaked respectively For continuous pretreatment, as a control group, the pretreatment reagents and their concentration and soaking time are the same as those of the corresponding examples, and then the performance test is carried out. Tensile performance, bending performance and impact performance were tested according to GB/T1040-2006, GB1449-2005 and GB/T1843-2008 respectively, and the test results are shown in Table 2.

Table 2

It can be seen from the above table that the mechanical properties of sisal fiber reinforced polylactic acid composites prepared by the chemical discontinuous treatment of two-end treatment and middle untreatment are generally improved. In Example 4 where the sisal fiber mass fraction is 20%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 4.01% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 20.22%; the tensile modulus increased by 7.69%. In Example 5 where the sisal fiber mass fraction is 30%, the bending strength of the composite material prepared by the pretreatment process of the present invention is improved by 28.21% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 79.35%; the tensile modulus increased by 21.01%. In Example 3 where the sisal fiber mass fraction is 40%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 6.62% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 59.38%; the tensile modulus increased by 17.59%.

Example 7

1. Put the NaOH solution with a mass concentration of 5% in the water tank. Fold a bunch of fibers that have been cut to 3cm in half and fix them on the iron stand with clamps. Adjust the height of the clamps so that 1/2 of the folded fiber part is immersed below the liquid level of the tank, and the remaining 1/2 is exposed to the air. Treat for 120 minutes; then Washing to neutrality can produce discontinuous pretreated plant fibers with solution treatment in the middle and untreated ends.

2. The above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid are added to an open mill at a weight ratio of 10:3 for mixing, and the discontinuously pretreated plant fibers account for 20% of the mass of the dried matrix resin , the mixing temperature was 175°C, and the mixing time was 10 minutes to obtain a composite material;

3. Put the composite material prepared in the above steps into the mold, specifically use a rectangular plate mold, the mold length, width, and thickness are 20cm, 10cm, and 4mm, respectively, and heat-press on a flat vulcanizing machine. The molding temperature is 210°C, the pressure is 10Mpa, and the molding time is 15min. Deflate 20 times during the hot pressing process, and the interval between each deflation is 3s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

Example 8

1. Put the NaOH solution with a mass concentration of 5% in the water tank. Fold a bunch of fibers that have been cut to 3cm in half and fix them on the iron stand with clamps. Adjust the height of the clamps so that 1/2 of the folded fiber part is immersed below the liquid level of the tank, and the remaining 1/2 is exposed to the air. Treat for 120 minutes; then Washing to neutrality can produce discontinuous pretreated plant fibers with solution treatment in the middle and untreated ends;

2. The above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid are added to an open mill in a weight ratio of 10:3 for mixing, and the discontinuously pretreated plant fibers account for 30% of the mass of the dried matrix resin , the mixing temperature was 185°C, and the mixing time was 8 minutes to obtain a composite material;

3. Put the composite material prepared in the above steps into the mold, specifically use a rectangular plate mold, the mold length, width, and thickness are 20cm, 10cm, and 4mm, respectively, and heat-press on a flat vulcanizing machine. The molding temperature is 200°C, the pressure is 9Mpa, and the molding time is 19min. During the hot pressing process, deflate 30 times, and the interval between each deflation is 3s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

Example 9

1. Put the NaOH solution with a mass concentration of 5% in the water tank. Fold a bunch of fibers that have been cut to 3cm in half and fix them on the iron stand with clamps. Adjust the height of the clamps so that 1/2 of the folded fiber part is immersed below the liquid level of the tank, and the remaining 1/2 is exposed to the air. Treat for 120 minutes; then Washing to neutrality can produce discontinuous pretreated plant fibers with solution treatment in the middle and untreated ends;

2. The above-mentioned non-continuously pretreated plant fibers and the dried matrix resin polylactic acid are added to an open mill in a weight ratio of 10:3 for mixing, and the discontinuously pretreated plant fibers account for 40% of the mass of the dried matrix resin , the mixing temperature was 200°C, and the mixing time was 5 minutes to obtain a composite material;

3. Put the composite material prepared in the above steps into the mold, specifically use a rectangular plate mold, the mold length, width, and thickness are 20cm, 10cm, and 4mm, respectively, and heat-press on a flat vulcanizing machine. The molding temperature is 190°C, the pressure is 8Mpa, and the molding time is 22min. Deflate 40 times during the hot pressing process, and the interval between each deflation is 2s, so that the gas in the mold is fully discharged, and the molded product is obtained; after the molded product is taken out, the burr and flash are removed to obtain a plate-shaped composite material product.

After the composite material products made in embodiment 7 to embodiment 9 are respectively made into splines (the spline size is the same as embodiment 1-embodiment 3), and the sisal fiber in each embodiment is fully soaked respectively For continuous pretreatment, as a control group, the pretreatment reagents and their concentration and soaking time are the same as those of the corresponding examples, and then the performance test is carried out. Tensile performance, bending performance and impact performance were tested according to GB/T1040-2006, GB1449-2005 and GB/T1843-2008 respectively, and the test results are shown in Table 3.

table 3

It can be seen from the above table that the mechanical properties of the sisal fiber reinforced polylactic acid composites prepared by the chemical discontinuous treatment of the middle section and the untreated ends are generally improved. In Example 7 where the sisal fiber mass fraction is 20%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 16.32% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 11.37%; the tensile modulus increased by 7.65%. In Example 8 where the sisal fiber mass fraction is 30%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 31.86% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 28.59%; the tensile modulus increased by 9.86%. In Example 9 where the sisal fiber mass fraction is 40%, the flexural strength of the composite material prepared by the pretreatment process of the present invention is improved by 15.82% relative to the sisal fiber reinforced polylactic acid material of the complete continuous soaking process; the impact strength is improved increased by 33.29%; the tensile modulus increased by 8.40%.

It can be seen from Tables 1, 2, and 3 that the mechanical properties of sisal fiber reinforced PLA/cellulose acetate composites prepared by chemical discontinuous treatment are generally improved. Because the comprehensive mechanical properties of composite materials are not only related to the interface bonding performance between the reinforcing fiber and the matrix material, but also related to the performance of the reinforcing fiber itself. It can be seen that the present invention, by means of chemical discontinuous treatment, removes impurities, increases the contact surface area of plant fiber and matrix material, improves its surface roughness to enhance the interfacial performance between the two, and can retain The mechanical properties of the original fiber greatly improve the tensile, bending and impact properties of the composite material. At the same time, when the composite material is impacted by an external force, the energy is transmitted from the thinned part of the fiber to the unrefined part of the fiber, and when the unrefined part with higher strength is torn, the energy is absorbed in large quantities, so the impact strength The most significant increase.

For those skilled in the art, according to the elaboration of the present invention in the foregoing specification and examples, the plant fibers are chemically discontinuously treated to prepare some improvements in plant fiber reinforced polymer matrix composites with excellent performance. Improvements to the present invention that deviate from the gist and scope of the present invention determined by the claims shall fall within the protection scope of the present invention.

Claims (3)

1. the method for preparing polymer composite material from plant fiber by chemical non-continuous pretreatment is characterized in that step is as follows:

(1) length has been reduced to the vegetable fibre of 2cm～3cm and fixed with fixture, the alignment jig height infiltrates in Chemical Pretreatment reagent 1/5～4/5 of plant fiber length, infiltrating time is 10min～120min, then, till vegetable fibre to the scrub raffinate after the washing infiltration is neutrality, obtain discontinuous pretreated vegetable fibre;

(2) above-mentioned discontinuous pretreated vegetable fibre and dried matrix resin are added in mixing facilities mixing, obtain matrix material; Discontinuous pretreated vegetable fibre accounts for 10%～50% of dried matrix resin quality;

(3), by above-mentioned composite material hot-pressed formation, obtain goods after moulding, then, through burr removal, overlap, make composite product;

Described Chemical Pretreatment reagent is alkali lye, grafting reagent or coupling reagent; The NaOH solution that described alkali lye is mass concentration 5%～20% or KOH solution; Described grafting reagent is alkylating reagent, acetylation reagent, benzoylation reagent or cyanoethylation reagent; The silane coupling agent that described coupling reagent is mass concentration 0.5%～2%, titanate coupling agent, organic chromium complex compound coupling agent or aluminic acid class coupling agent;

The phloem fiber that described vegetable fibre is more than one fibers in flax, hemp, jute, ramie, mestha and sisal hemp, or the cloth of above-mentioned phloem fiber.

2. method according to claim 1, is characterized in that described mixing melting temperature is 175 ℃～210 ℃, and mixing time is 5min～10min.

3. method according to claim 1, is characterized in that described hot-forming temperature is 190 ℃～210 ℃, pressure 8MPa～12MPa, and clamp time is 15 min～22min; In hot pressing, venting is 20 times～40 times, and be 2 s～3s the interval time of at every turn exitting.