阅读说明：本技术 一种低密度复合材料及其制备方法 (Low-density composite material and preparation method thereof ) 是由 何少波 李小华 范仕杰 向上 邓朝阳 于 2020-12-15 设计创作，主要内容包括：本发明涉一种低密度复合材料及其制备方法,所述复合材料含有以下重量份的组分：液体聚丁二烯树脂100份、环氧化聚丁二烯树脂5～20份、高沸点活性交联剂15～35份、环氧固化剂0.1～0.5份、过氧化物引发剂0.5～3.0份、阻聚剂0.01～0.05份、纳米金属氧化物2～7份、偶联剂0.15～0.35和麻纤维100～180份。本发明提供的复合材料,通过采用特定配方制作,具有低密度、机械性能好、韧性好等优点。(The invention relates to a low-density composite material and a preparation method thereof, wherein the composite material comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 5-20 parts of epoxidized polybutadiene resin, 15-35 parts of high-boiling-point active cross-linking agent, 0.1-0.5 part of epoxy curing agent, 0.5-3.0 parts of peroxide initiator, 0.01-0.05 part of polymerization inhibitor, 2-7 parts of nano metal oxide, 0.15-0.35 part of coupling agent and 100-180 parts of fibrilia. The composite material provided by the invention is prepared by adopting a specific formula, and has the advantages of low density, good mechanical property, good toughness and the like.)

1. The low-density composite material is characterized by comprising the following components in parts by weight: 100 parts of liquid polybutadiene resin, 5-20 parts of epoxidized polybutadiene resin, 15-35 parts of high-boiling-point active cross-linking agent, 0.1-0.5 part of epoxy curing agent, 0.5-3.0 parts of peroxide initiator, 0.01-0.05 part of polymerization inhibitor, 2-7 parts of nano metal oxide, 0.15-0.35 part of coupling agent and 100-180 parts of fibrilia.

2. The composite material according to claim 1, characterized in that it comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 6-18 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.2-0.5 part of epoxy curing agent, 1.0-3.0 parts of peroxide initiator, 0.02-0.05 part of polymerization inhibitor, 3-7 parts of nano metal oxide, 0.2-0.35 part of coupling agent and 110-160 parts of fibrilia.

3. The composite material according to claim 2, characterized in that it comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 8-15 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.2-0.3 part of epoxy curing agent, 1.5-3.0 parts of peroxide initiator, 0.02-0.04 part of polymerization inhibitor, 3-5 parts of nano metal oxide, 0.2-0.3 part of coupling agent and 120-150 parts of fibrilia.

4. The composite material according to claim 3, characterized in that it comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 8-15 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.2-0.3 part of epoxy curing agent, 2.0-3.0 parts of peroxide initiator, 0.03-0.04 part of polymerization inhibitor, 3-5 parts of nano metal oxide, 0.2-0.3 part of coupling agent and 130-150 parts of fibrilia.

5. The composite material according to claim 4, characterized in that it comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 12-15 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.25-0.3 part of epoxy curing agent, 2.0-3.0 parts of peroxide initiator, 0.03-0.04 part of polymerization inhibitor, 4-5 parts of nano metal oxide, 0.25 part of coupling agent and 140-150 parts of fibrilia.

6. The composite material according to claim 5, characterized in that it comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 15 parts of epoxidized polybutadiene resin, 20 parts of active cross-linking agent, 0.3 part of epoxy curing agent, 2.0 parts of peroxide initiator, 0.03 part of polymerization inhibitor, 5 parts of nano metal oxide, 0.25 part of coupling agent and 150 parts of fibrilia.

7. Composite material according to any one of claims 1 to 6, characterized in that the liquid polybutadiene resin contains 65% to 95% of 1, 2-polybutadiene, the remainder being cyclized polybutadiene or 1, 4-polybutadiene.

8. The composite material as claimed in any one of claims 1 to 6, wherein the epoxidized polybutadiene resin is a low viscosity epoxidized polybutadiene resin having a molecular weight of 800-900.

9. Composite according to any one of claims 1 to 6, characterized in that the reactive cross-linker is a high-boiling reactive cross-linker, in particular one or a mixture of dicyclopentadiene acrylate, dicyclopentadiene methacrylate, isophthalate diallyl, triallyl trimellitate, tripropylene glycol diacrylate and trimethylolpropane triacrylate, preferably dicyclopentadiene acrylate or trimethylolpropane triacrylate.

10. A method for preparing a low density composite, the method comprising the steps of:

1) weighing the components of the composite material according to any one of claims 1 to 9, mixing and heating the liquid polybutadiene resin and the epoxidized polybutadiene resin to 70-90 ℃, fully stirring, adding the active cross-linking agent and the epoxy curing agent, and stirring for reaction for 20-30 min;

2) cooling to below 50 ℃, adding a peroxide initiator, a polymerization inhibitor, a nano metal oxide and a coupling agent, fully and uniformly stirring, adding fibrilia, and infiltrating to obtain a prepreg;

3) and (3) pressing and curing the prepared prepreg in a mold at the temperature of 125-155 ℃ for 5-15 min.

Technical Field

The invention relates to the field of composite technology, and relates to a low-density composite material and a preparation method thereof.

Background

The history of the use of the composite material can be traced back to ancient times, and the rice straw or wheat straw reinforced clay used from ancient times to present and the reinforced concrete used for hundreds of years are both compounded by two materials. In the 40's of the 20 th century, glass fiber reinforced plastics (commonly known as glass fiber reinforced plastics) were developed due to the needs of the aviation industry, and the name of composite materials has since emerged.

The fiber reinforced thermosetting composite material has high specific strength and specific rigidity and good mechanical property and corrosion resistance, and is widely applied to the fields of transportation, building materials, municipal engineering and the like.

The glass fiber reinforced composite material is the most common type of fiber reinforced thermosetting composite material, and is a material compounded by taking glass fibers and products thereof as a reinforcing material and a matrix material through a certain molding process, wherein the density of the material is generally 1.7-2.0g/cm³The automobile body has the advantages of light weight, high strength, corrosion resistance and the like, and can reduce the weight of the automobile, improve the performance of the automobile, reduce the manufacturing cost of automobile parts, accelerate the assembly speed of the automobile, save fuel and the like when being applied to the automobile industry. Can be used in automobiles to make: front end panels, air conditioning ducts, exhaust valves, engine hoods, bumpers, trunk lids, body panels, roof panels, chassis, base members, instrument panels, mufflers, exhaust filtration, fuel gas cylinders, upholstery, friction materials, and the like.

With the wider application field of the glass fiber composite material, the demand for the glass fiber composite material is different, and the glass fiber composite material is gradually improved. In the end of 60 years, in order to meet the requirements of materials used in advanced technologies such as aerospace and the like, load-bearing properties of reinforced materials made of high-performance fibers (such as carbon fibers, boron fibers, aramid fibers, silicon carbide fibers and the like) are developed and produced in sequence, and the composite materials are called advanced composite materials. According to different base materials, the composite material is divided into resin base, metal base and ceramic base composite material.

Compared with glass fiber and synthetic fiber, natural fiber has environment-friendly and biodegradable properties, and natural fiber reinforced resin matrix composite material is also called green composite material, and has very wide application prospect.

Under the requirement of light weight in the automotive field such as new energy, the density of glass fiber composite materials is still large, and development of composite materials with lower density is necessary.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the resin-based fiber composite material with low density, good heat resistance, mechanical property and environmental protection.

In order to solve the technical problems, the invention adopts the following technical scheme:

a low-density composite material comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 5-20 parts of epoxidized polybutadiene resin, 15-35 parts of high-boiling-point active cross-linking agent, 0.1-0.5 part of epoxy curing agent, 0.5-3.0 parts of peroxide initiator, 0.01-0.05 part of polymerization inhibitor, 2-7 parts of nano metal oxide, 0.15-0.35 part of coupling agent and 100-180 parts of fibrilia.

Preferably, the composite material comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 6-18 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.2-0.5 part of epoxy curing agent, 1.0-3.0 parts of peroxide initiator, 0.02-0.05 part of polymerization inhibitor, 3-7 parts of nano metal oxide, 0.2-0.35 part of coupling agent and 110-160 parts of fibrilia.

Further preferably, the composite material comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 8-15 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.2-0.3 part of epoxy curing agent, 1.5-3.0 parts of peroxide initiator, 0.02-0.04 part of polymerization inhibitor, 3-5 parts of nano metal oxide, 0.2-0.3 part of coupling agent and 120-150 parts of fibrilia.

Still more preferably, the composite material comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 8-15 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.2-0.3 part of epoxy curing agent, 2.0-3.0 parts of peroxide initiator, 0.03-0.04 part of polymerization inhibitor, 3-5 parts of nano metal oxide, 0.2-0.3 part of coupling agent and 130-150 parts of fibrilia.

The composite material has good effect, and comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 12-15 parts of epoxidized polybutadiene resin, 20-35 parts of active cross-linking agent, 0.25-0.3 part of epoxy curing agent, 2.0-3.0 parts of peroxide initiator, 0.03-0.04 part of polymerization inhibitor, 4-5 parts of nano metal oxide, 0.25 part of coupling agent and 140-150 parts of fibrilia.

The composite material has good effect, and comprises the following components in parts by weight: 100 parts of liquid polybutadiene resin, 15 parts of epoxidized polybutadiene resin, 20 parts of active cross-linking agent, 0.3 part of epoxy curing agent, 2.0 parts of peroxide initiator, 0.03 part of polymerization inhibitor, 5 parts of nano metal oxide, 0.25 part of coupling agent and 150 parts of fibrilia.

In the above composite material:

the liquid polybutadiene resin contains 65-95 wt% of 1, 2-polybutadiene, and the other part of polybutadiene is cyclized polybutadiene or 1, 4-polybutadiene.

The epoxidized polybutadiene resin is low-viscosity epoxidized polybutadiene resin with the molecular weight of 800-900;

the active crosslinking agent is a high-boiling point active crosslinking agent, specifically is one or a mixture of more of dicyclopentadiene acrylate, dicyclopentadiene methacrylate, m-phthalic acid diacrylate, m-phthalic acid diallyl ester, triallyl trimellitate, tripropylene glycol diacrylate and trimethylolpropane triacrylate, and is preferably dicyclopentadiene acrylate or trimethylolpropane triacrylate.

The epoxy curing agent is an organic urea epoxy curing agent, and preferably, the curing agent is micronized aromatic urea with the particle size of 5-20 mu m.

The peroxide initiator is tert-butyl peroxybenzoate, dicumyl peroxide, di-tert-butyl hydroperoxide, benzoyl peroxide or benzoyl acetyl peroxide and the like, and preferably, the peroxide initiator is di-tert-butyl hydroperoxide or dicumyl peroxide.

The polymerization inhibitor comprises 2, 6-di-tert-butyl-4-methylphenol, hydroquinone methyl ether, hydroquinone, methyl hydroquinone or tert-butyl hydroquinone and the like, and preferably, the polymerization inhibitor is 2, 6-di-tert-butyl-4-methylphenol or hydroquinone methyl ether.

The nano metal oxide is one or a mixture of more than two of nano silicon dioxide, nano aluminum oxide, nano zinc oxide and nano titanium dioxide.

The coupling agent is an epoxy group-containing silane coupling agent.

The hemp fiber is obtained from various hemp plants, and comprises ramie fiber, jute fiber, flax fiber, hemp fiber, sisal fiber and coconut fiber. Preferably, the hemp fibers are ramie fibers, sisal fibers, flax fibers or hemp fibers.

The invention also provides a preparation method of the composite material, which comprises the following steps:

1) weighing the components according to the raw materials, mixing and heating the liquid polybutadiene resin and the epoxidized polybutadiene resin to 70-90 ℃, fully stirring, adding the active cross-linking agent and the epoxy curing agent, and stirring for reaction for 20-30 min;

2) cooling to below 50 ℃, adding a peroxide initiator, a polymerization inhibitor, a nano metal oxide and a coupling agent, fully and uniformly stirring, adding fibrilia, and infiltrating to obtain a prepreg;

3) and (3) pressing and curing the prepared prepreg in a mold at the temperature of 125-155 ℃ for 5-15 min.

Preferably, the method comprises the steps of:

1) weighing the components according to the raw materials, mixing and heating the liquid polybutadiene resin and the epoxidized polybutadiene resin to 80-90 ℃, fully stirring, adding the active cross-linking agent and the epoxy curing agent, and stirring for reaction for 25-30 min;

2) cooling to below 50 ℃, adding a peroxide initiator, a polymerization inhibitor, a nano metal oxide and a coupling agent, fully and uniformly stirring, adding fibrilia, and infiltrating to obtain a prepreg;

3) and (3) pressing and curing the prepared prepreg in a mold at the temperature of 125-155 ℃ for 5-15 min.

The low-density composite material provided by the invention is mainly applied to related composite material products needing to reduce weight, including composite material products used in the field of new energy automobiles, composite material products in the field of rail transit and the like.

The invention has the following advantages:

1. the low-density composite material provided by the invention comprises the following components in parts by weight:

1) the liquid polybutadiene resin is a special resin variety and has many characteristics, and the density is 0.86-0.91g/cm³Is less dense than most thermosetting resins such as unsaturated polyester resins and epoxy resins. The polybutadiene resin mainly with 1, 2-polybutadiene structure has unsaturated double bonds and can be cured into tough cured products, and the vinyl functional groups of the polybutadiene resin have reactivity and have similar technological operability to that of unsaturated polyester resins. The cured polybutadiene resin has excellent electrical property, good chemical resistance, water resistance, moisture resistance, weather resistance, heat resistance and mechanical property, and the laminated material has outstanding impact resistance.

In the used liquid polybutadiene resin, when the content of 1, 2-polybutadiene is less than 65%, the resin is too soft, and the hardness and the mechanical strength are lost; if the content is more than 95%, the viscosity of the resin is too high and it is inconvenient to use. For this reason, the preferred polybutadiene resin of the present invention is a liquid resin containing 65 to 95% by weight of 1, 2-polybutadiene.

2) The epoxidized polybutadiene resin contains an unsaturated bond in addition to an epoxy group and a hydroxyl group in its molecular structure, and therefore, not only can the epoxy resin be cured by a conventional epoxy curing agent, but also a double bond-containing monomer can be crosslinked therewith under initiation of a peroxide. The epoxy polybutadiene resin cured product has excellent performance, and the heat distortion temperature can reach 250 ℃. On one hand, epoxy groups of the epoxidized polybutadiene resin improve the interface bonding performance of matrix resin and fibers, and on the other hand, double-bond groups react with double bonds in the polybutadiene resin through crosslinking. The epoxidized polybutadiene resin is used in an amount of 5 to 20 parts by weight, and if it is less than 5 parts by weight, the interface bonding effect is not remarkably improved, and if it exceeds 20 parts by weight, other problems may be caused. The epoxidized polybutadiene resin is low-viscosity resin with the molecular weight of 800-900, and if the molecular weight is too high, the viscosity of the resin is too high, so that the use process is influenced.

3) Hemp fiber is a generic term for fibers obtained from various hemp plants. Fibers derived from various hemp plants include bast fibers from the cortex of annual or perennial herbaceous dicotyledonous plants and leaf fibers from monocotyledonous plants. Bast fiber crops mainly include ramie, jute, ramie, hemp (hemp), flax, yarrow fiber and the like. All fibrilia is cellulose fiber, the basic chemical composition is cellulose, and other non-fibrous substances such as pectin, hemicellulose, lignin, fatty wax and the like are associated with the cellulose. The cellulose content in the chemical components of various fibrilia is about 75 percent. The density of the fibrilia is 1.3-1.5g/cm³While only the glass fiber has the density of 2.5g/cm³About 60% of the total.

4) The active cross-linking agent is a high-boiling point active cross-linking agent, the using amount is 15-35 parts by weight, if the viscosity of the resin is lower than 15 parts by weight, the using process of the resin is affected too high, and if the viscosity of the resin is higher than 35 parts by weight, the performance of the composite material is reduced.

5) The peroxide initiator has the characteristics of medium decomposition temperature, long service life, good curing performance and the like. The initiator is used in an amount of about 0.5 to 3.0 parts by weight, and if the amount of the initiator is less than 0.5 part by weight, complete curing may not be achieved, and if it exceeds 3.0 parts by weight, material stability is affected and gelation may occur during storage.

6) Of the polymerization inhibitors, 2, 6-di-t-butyl-4-methylphenol is preferred, having the best effect of inhibiting polymerization. The amount of the polymerization inhibitor is about 0.01-0.05 part by weight, if the amount of the polymerization inhibitor is less than 0.01 part by weight, the material may be gelled during storage, and if the amount of the polymerization inhibitor exceeds about 0.05 part by weight, the gelling time is too long, and resin is easily lost during the molding process, thereby affecting the product performance.

The epoxy curing agent, preferably micronized aromatic organic urea with the particle size of 5-20 μm, has good resin miscibility and excellent curing effect. The amount of the curing agent is 0.2-0.5 part by weight, if the amount is less than 0.2 part by weight, the curing crosslinking density of the epoxy resin is insufficient, the mechanical strength of the cured product is low, and if the amount exceeds 0.5 part by weight, the resin reacts too fast, and the performance of the cured product is influenced.

The coupling agent is preferably an epoxy group-containing silane coupling agent, and the epoxy group silane coupling agent can enable a resin matrix, metal oxides and fibers to form a good composite material interface and improve the mechanical properties of the composite material.

The heat resistance of the composite material is mainly determined by the heat resistance of a resin matrix, the liquid polybutadiene resin mainly contains 1, 2-polybutadiene structure, on one hand, the liquid polybutadiene resin has the impact toughness of a rubber material, on the other hand, the liquid polybutadiene resin is actually thermosetting resin because the liquid polybutadiene resin can be in crosslinking reaction with other double bond-containing resin/monomer, and a cured product of the liquid polybutadiene resin has good heat resistance through the reaction with an active crosslinking agent. In addition, the epoxy polybutadiene resin has good impact strength, bending strength and heat resistance of a cured product, and can increase the heat resistance of the composite material and improve the mechanical property.

2. The inventor knows that fibrilia has the advantages of low density, high flame retardant property and the like (blackish and bright, automobile technology and material, 2015 7 th year, 56 pages) through literature, and attempts to replace glass fiber with fibrilia based on the advantages of fibrilia, but when the fibrilia is used alone, the fibrilia is not easy to form, so that the application range of the fibrilia is limited, and therefore, the fibrilia is improved in series:

first, screening of resins, polyurethane resins, epoxy resins, silicone resins, vinyl resins, and the like was performed, and it was found that: when combined with polyurethane resin, the polyurethane resin has insufficient mechanical properties such as toughness, poor impact strength and low tensile strength; when the epoxy resin is combined with the epoxy resin, the bending strength is good, the tensile strength is good, the impact toughness is general, the density is high, and the forming process is complex; when the fiber is combined with organic silicon resin, the bending strength is low, the interface bonding between the fiber and the resin is poor, and the bonding cannot be improved even if a coupling agent is added; when the material is combined with vinyl resin, the bending strength is better, the impact toughness is general, and the density is higher; in combination with polybutadiene resin, various mechanical properties are slightly increased with less influence on density … …, and therefore, polybutadiene resin is finally selected;

secondly, the adhesive property of the polybutadiene is low due to the molecular chain structure of the polybutadiene, even if a coupling agent is used, the interface of the polybutadiene and a composite material of fibrilia is poor, the impact strength is reduced greatly, in order to enhance the viscosity of the polybutadiene, the inventor tries to add epoxy resin (adhesive is preferred) into the polybutadiene, and the proportion relation is very critical, and finally 100 parts of liquid polybutadiene resin and 5-20 parts of epoxy polybutadiene resin are limited as described above.

Thirdly, a good interface transition layer is formed between the matrix resin and the plant fiber through the epoxy group in the coupling agent, and the good overall performance of the composite material is realized.

3. The invention has good environmental protection performance, and the environmental protection performance of the composite material comprises the discharge amount of VOC (volatile organic compounds) of raw materials in the processing and forming process and the influence on the health of operators. The formula of the invention greatly avoids the generation of VOC from raw materials, on one hand, the VOC content of polybutadiene and epoxidized polybutadiene resin is extremely low, and on the other hand, the VOC emission is also very low by selecting the high-boiling-point allyl structure active cross-linking agent. The common reinforcing fibers such as glass fibers, carbon fibers, basalt fibers and the like in the composite material have the problem that the skin is allergic after partial personnel contact more or less, and the common plant fibers in the invention basically have no allergy problem for operators, so that the real environmental protection is realized.

4. The composite material provided by the invention is prepared by adopting a specific formula, and has the advantages of low density, good mechanical property, good toughness and the like.

Detailed Description

The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The raw material sources are as follows:

liquid polybutadiene resins containing 65-90% by weight of 1, 2-polybutadiene structure, available from sartomer (guangzhou) chemical co;

a low viscosity epoxidized polybutadiene resin having a molecular weight of 800-900 is available from Sartomer chemical Co., Ltd.

Example 1: low-density composite material

1. Raw materials:

100g of liquid polybutadiene resin containing 90% of 1, 2-polybutadiene structure, 15g of epoxidized polybutadiene resin, 20g of dicyclopentadiene acrylate, 0.3g of organic urea epoxy curing agent, 2.0g of dicumyl peroxide, 0.03g of 2, 6-di-tert-butyl-4-methylphenol and nano Al₂O₃5g of KH560 coupling agent, 0.25g of flax fiber and 150g of flax fiber.

2. The preparation method comprises the following steps:

weighing liquid polybutadiene resin and epoxidized polybutadiene resin according to raw materials, mixing and heating to 90 ℃, fully stirring, adding dicyclopentadiene acrylate and an organic urea epoxy curing agent, stirring and reacting for 30min, cooling to below 50 ℃, adding dicumyl peroxide, 2, 6-di-tert-butyl-4-methylphenol and nano Al₂O₃And fully and uniformly stirring the mixture and KH560 coupling agent, adding flax fiber, and infiltrating to obtain the prepreg. And pressing and curing the prepared prepreg in a mold at 150 ℃ for 5 min.

Example 2: low-density composite material

1. Raw materials:

100g of liquid polybutadiene resin containing 75% of 1, 2-polybutadiene structure, 8g of epoxidized polybutadiene resin, 20g of m-phthalic acid diacrylate, 0.2g of organic urea epoxy curing agent, 2.5g of tert-butyl peroxybenzoate, 0.04g of tert-butylhydroquinone, 3g of nano titanium dioxide, 0.25g of A-187 coupling agent and 130g of sisal fiber.

2. The preparation method comprises the following steps:

weighing liquid polybutadiene resin and epoxidized polybutadiene resin according to raw materials, mixing and heating to 70 ℃, fully stirring, adding m-phthalic acid diacrylate and organic urea epoxy curing agent, stirring and reacting for 20min, cooling to below 50 ℃,adding tert-butyl peroxybenzoate, tert-butylhydroquinone and nano Al₂O₃And the A-187 coupling agent are fully and uniformly stirred, sisal fibers are added, and the prepreg is prepared after infiltration. And pressing and curing the prepared prepreg in a mold at 155 ℃ for 8 min.

Example 3: low-density composite material

1. Raw materials:

100g of liquid polybutadiene resin containing 85% of 1, 2-polybutadiene structure, 12g of epoxidized polybutadiene resin, 35g of trimethylolpropane triacrylate, 0.25g of organic urea epoxy curing agent, 3.0g of di-tert-butyl hydroperoxide, 0.04g of hydroquinone methyl ether, 4g of nano silicon dioxide, 0.25g of KH560 coupling agent and 140g of sisal fiber.

2. The preparation method comprises the following steps:

weighing liquid polybutadiene resin and epoxidized polybutadiene resin according to raw materials, mixing and heating to 80 ℃, fully stirring, adding trimethylolpropane triacrylate and an organic urea epoxy curing agent, stirring and reacting for 25min, cooling to below 50 ℃, adding di-tert-butyl hydroperoxide and hydroquinone methyl ether, nano silicon dioxide and a KH560 coupling agent, fully stirring uniformly, adding sisal fibers, and infiltrating to obtain a prepreg. And pressing and curing the prepared prepreg in a 125 ℃ mold for 15 min.

Example 4: low-density composite material

1. Raw materials:

100g of liquid polybutadiene resin with a structure of 80% 1, 2-polybutadiene, 10g of epoxidized polybutadiene resin, 25g of tripropylene glycol diacrylate, 0.3g of organic urea epoxy curing agent, 1.5g of benzoyl peroxide acetyl, 0.02g of 2, 6-di-tert-butyl-4-methylphenol, 3g of nano zinc oxide, 0.25g of KH560 coupling agent and 120g of ramie fibers.

2. The preparation method comprises the following steps:

polybutadiene resin and epoxidized polybutadiene resin are weighed according to raw materials, mixed and heated to 85 ℃, after full stirring, tripropylene glycol diacrylate and an organic urea epoxy curing agent are added, stirring reaction is carried out for 20min, benzoyl peroxide acetyl, 2, 6-di-tert-butyl-4-methylphenol, nano silicon dioxide and a KH560 coupling agent are added, full stirring is carried out, ramie fibers are added, and the prepreg is prepared after infiltration. And (3) pressing and curing the prepared prepreg in a 135 ℃ mould for 10 min.

Comparative example 1: composite material

1. Raw materials:

100g of o-benzene type unsaturated polyester resin, 8g of poly-p-styrene resin, 15g of styrene, 1.5g of tert-butyl peroxybenzoate, 0.02g of 2, 6-di-tert-butyl-4-methylphenol, 75g of 800-mesh calcium carbonate and 90g of glass fiber.

2. The preparation method comprises the following steps:

weighing the o-benzene type unsaturated polyester resin, the poly-p-styrene resin, the styrene, the tert-butyl peroxybenzoate and the 2, 6-di-tert-butyl-4-methylphenol according to the raw materials, fully stirring, adding 800 meshes of calcium carbonate, stirring for 20min, adding the glass fiber, and infiltrating to obtain the prepreg. And (3) pressing and curing the prepared prepreg in a mold at 145 ℃ for 10 min.

Comparative example 2: composite material

1. Raw materials:

100g of o-benzene type unsaturated polyester resin, 8g of poly-p-styrene resin, 15g of styrene, 1.5g of tert-butyl peroxybenzoate, 0.02g of 2, 6-di-tert-butyl-4-methylphenol, 75g of 800-mesh calcium carbonate and 90g of flax fiber.

2. The preparation method comprises the following steps:

weighing the o-benzene type unsaturated polyester resin, the poly-p-styrene resin, the styrene, the tert-butyl peroxybenzoate and the 2, 6-di-tert-butyl-4-methylphenol according to the raw materials, fully stirring, adding 800 meshes of calcium carbonate, stirring for 20min, adding flax fibers, and infiltrating to obtain the prepreg. And (3) pressing and curing the prepared prepreg in a mold at 145 ℃ for 10 min.

Experimental example 1: performance detection

1. Sample preparation: examples 1-4 provided composites, control 1 was comparative example 1 and control 2 was flax fiber.

2. The detection method comprises the following steps:

impact strength: an index for measuring the toughness of materials is determined according to the part 1 of GB/T1043.1-2008 plastic simple supported beam impact performance: the impact strength is tested by the non-instrumented impact test scheme;

bending strength: testing the bending strength according to a GB/T9341-2008 plastic bending performance test method;

tensile strength and elongation at break: the tensile properties of the plastics are measured according to GB/T1040-2008;

density: the mass of a unit volume of a material in an absolute compact state is calculated according to the following formula: m/v, where m is the mass (g) of the material in the dry state and v is the volume of the material in the absolutely dense state;

load heat distortion temperature: part 2, plastics and hard rubber, were measured according to GB/T1634.2-2019 plastics load deformation temperature.

3. And (3) detection results: see Table 1

Table 1: formula of composite material obtained from each sample and performance detection result

Test items	Control group 1	Control group 2	Example 1	Example 2	Example 3	Example 4
							Density (g/cm)3)	1.75	1.55	1.21	1.23	1.22	1.25
Impact Strength (KJ/m)2)	89	90	123	91	122	95
							Flexural Strength (MPa)	118	115	195	122	176	147
Tensile Strength (MPa)	52	57	68	58	65	61
							Elongation at Break (%)	1.9	2.2	2.7	2.8	2.9	2.4
Load Heat distortion temperature (. degree. C.)	200	200	220	200	210	200

Note: the impact strength test sample adopts a type 1 unnotched test sample and is subjected to lateral impact. The angular impact results are related to the fiber direction, and there is no fiber direction problem in the present invention.

Table 1 the results show that: impact strength, bending strength and tensile strength, the best results were obtained in examples 1 and 3; elongation at break is best achieved with examples 2 and 3; the density was the lowest for the composite material of example 1, and the effect of weight reduction was most pronounced.

The results show that: compared with the contrast glass fiber composite material, the density of the composite material is greatly reduced, and the product

The weight reduction can reach 30%, and meanwhile, the composite material has good mechanical properties.

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.