CN115785328B - A method for preparing partially cross-linked PMMA and its composite materials - Google Patents

Abstract

The invention belongs to the technical field of synthesis of high polymer resin and composite materials thereof, and particularly relates to a preparation method of partially crosslinked PMMA and a preparation method of a composite material thereof. The long chains of the partially cross-linked PMMA are tightly connected through covalent bonds to form a stable three-dimensional network structure, the strength and toughness of the PMMA are enhanced simultaneously by adjusting the addition amount of diisocyanate, and the tensile strength, the impact strength and the elongation at break can be respectively improved to 85MPa and 33KJ/m ² 10 percent of the PMMA resin and the property of recycling and reusing the PMMA resin are maintained; meanwhile, the composite material prepared from the partially crosslinked PMMA and the fiber reinforced material has excellent mechanical properties. The preparation method disclosed by the invention has the advantages of few additives, simple process, no catalyst, mild and controllable reaction, ensures that the obtained partially crosslinked PMMA is used for preparing the composite material under the vacuum infusion molding process, and has higher application value.

Description

A method for preparing partially cross-linked PMMA and its composite materials

Technical field

The invention belongs to the technical field of synthesis of polymer resin and its composite materials, and specifically relates to a preparation method of partially cross-linked PMMA and its composite materials.

Background technique

Polymethyl methacrylate (PMMA) is an important transparent engineering plastic. Due to its light weight, good light transmittance, easy processing, and recyclability, it is widely used in optical materials, construction and packaging industries. has been widely used in. However, PMMA products often have defects such as low strength and insufficient toughness, which limits their wide-scale promotion and application.

In view of the above-mentioned defects of PMMA products, nanoparticles, core-shell modifiers, rubber elastomers and other materials are often used to toughen and modify PMMA; metal oxides such as alumina, chopped fibers such as glass fiber, and cellulose are used. Materials such as lignin enhance the modification of PMMA. For example, the patent with publication number CN109735035A uses a polyolefin macroinitiator containing reactive functional groups and a toughener prepared by in-situ polymerization of Methyl methacrylate (MMA) monomer to modify the PMMA resin. The impact strength of PMMA resin has been increased to 33KJ/m ² , but its tensile strength is poor, only about 62MPa; the patent with publication number CN 109370133 A uses extracted lignin to modify the prepolymerized MMA solution, making the organic The tensile strength of the glass increased by 13%, but its toughness properties still failed to be optimized. It can be seen that most of the existing modification methods can only improve one aspect of the performance alone, and it is difficult to achieve enhanced modification at the same time as toughening modification. They may even increase the brittleness of the product while enhancing the modification, causing the toughness performance to decrease. .

The patent number CN114806055A provides a reinforced and toughened PMMA sheet and its manufacturing method. It uses polymethyl methacrylate polymer chains, polyol polymers and short-range connection units as raw material components, and is reinforced through casting and polymerization. Toughened PMMA sheets, under the action of polyol polymers and short-range connecting units, the molecular chains of PMMA are entangled and interlocked with each other, and the polyol polymers are laterally connected, thus improving the toughness and strength of PMMA sheets. Compared with In the comparative example, the tensile strength of PMMA is increased to 75MPa, an increase of about 15%; the unnotched impact strength of a simply supported beam is increased to 25KJ/m ² , an increase of about 60%. This patent modifies the strength of PMMA resin from the perspective of molecular structure. and toughness to achieve simultaneous modification of both. However, a catalyst is required in this modification method to obtain a better reaction effect, and the short-range connecting unit in this modification method cannot directly connect the polymethyl methacrylate polymer chain. Together, additional polyol polymer needs to be added to connect it to the short-range connection unit. Therefore, there are many modification additives in PMMA sheets, and the modification method is cumbersome and difficult to control.

Therefore, it is of great value to develop a modification method that can simultaneously toughen and strengthen PMMA with few additives, simple operation, environmentally friendly modification process, and no use of catalysts.

Contents of the invention

In order to overcome the above-mentioned shortcomings in the prior art, the present invention proposes a preparation method of partially cross-linked PMMA and its composite material.

In order to achieve the above objects, the technical solution of the present invention is implemented as follows:

A preparation method of partially cross-linked PMMA, the steps are as follows:

(1) Dissolve the diisocyanate into MMA, then drop it into the mixture of hindered amine acrylate and MMA, stir and react at room temperature for 1-60 minutes, and obtain product 1. Keep the mixture containing product 1 for later use;

(2) Add the initiator required for the polymerization reaction to the mixed liquid containing product 1 in step (1) and mix. Under certain conditions, product 1 and MMA undergo a polymerization reaction to obtain partially cross-linked PMMA.

Preferably, the ratio of the total amount of MMA to the amount of hindered amine acrylate and diisocyanate is 1:(0.05-0.5):(0.025-0.25), wherein the amount of hindered amine acrylate is 2 times the amount of diisocyanate material; the added amount of the initiator is 0.1-5% of the total mass of MMA and hindered amine acrylate.

Preferably, the diisocyanate is any one of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and 4,4'-dicyclohexylmethane diisocyanate (HMDI); the hindered amine acrylate is any one of tert-butylaminoethyl methacrylate, tert-butylaminoethyl acrylate, isopropylaminoethyl methacrylate, isopropylaminoethyl acrylate, piperidineaminoethyl acrylate and piperidineaminoethyl methacrylate; the initiator is a thermal decomposition initiator and/or a redox initiator; the thermal decomposition initiator is an azo compound and/or a peroxide compound; the redox initiator is a combination of a peroxide and a reducing agent.

More preferably, the azo compound is azobisisobutyronitrile (2,2'-Azobis(2-methylpropionitrile), AIBN for short) or azobisisoheptanitrile (2,2'-Azobis(2, 4-dimethyl)valeronitrile (ABVN for short); the peroxide compound is benzoyl peroxide (Benzoyl peroxide, BPO for short); the peroxide is BPO or Dilauroyl peroxide (Dilauroyl peroxide, LPO for short); The reducing agent is N,N-Dimethyl-p-toluidine (DMT for short) and/or N,N-dimethylaniline (DMA for short) .

Preferably, the polymerization reaction conditions in step (2) are: reaction at -20~100°C for 0.1-48h, and then post-curing at 60-120°C for 0.1-48h.

The preparation reaction process of the partially cross-linked PMMA is as follows:

in, Is the molecular structure of diisocyanate,/> is the molecular structure of hindered amine acrylate,/> is the molecular structure of product 1,/> Is the molecular structure of methyl methacrylate (MMA),/> It is the structure of partially cross-linked PMMA; where m is an integer ≥1, n is an integer ≥1; R ₁ is hydrogen or methyl, and R ₂ is a large sterically hindered hindered group, including tert-butyl and isopropyl. or piperidine.

The preparation principle of the partially cross-linked PMMA: monomeric hindered amine acrylate and diisocyanate are first subjected to polyurea reaction to prepare product 1 containing large sterically hindered urea groups in the molecular structure, and both ends of product 1 contain unsaturated double bonds , under the action of the initiator, a free radical copolymerization reaction occurs between the unsaturated double bonds in product 1 and the MMA monomer, and the two ends of product 1 are grafted with PMMA molecular chains, that is, at this time, the long chain of PMMA molecules is due to the product 1 form cross-links with each other, thereby forming partially cross-linked PMMA. At a certain degree of cross-linking, the force between PMMA molecular chains is enhanced, and the tensile strength is improved. At the same time, by adjusting the amount of diisocyanate added, the strength and toughness of this partially cross-linked PMMA can be improved at the same time.

The present invention also includes partially cross-linked PMMA prepared by the above method.

The present invention also includes a partially cross-linked PMMA composite material, which contains the above-mentioned partially cross-linked PMMA and fiber reinforcement materials.

Preferably, the fiber reinforcement material is chopped fiber or continuous fiber; the chopped fiber is one or more of chopped carbon fiber, chopped glass fiber, chopped aramid fiber and chopped high-density polyethylene fiber. kind; the continuous fiber is one or more of carbon fiber, glass fiber, basalt fiber and aramid fiber; the continuous fiber is continuous fiber yarn or fiber cloth.

The preparation method of the above partially cross-linked PMMA composite material is any one of injection molding, vacuum-assisted infusion molding, compression molding, winding molding and pultrusion.

Preferably, the specific steps for preparing partially cross-linked PMMA composite materials by the vacuum-assisted infusion molding method are as follows:

Step a: Dissolve diisocyanate into MMA, then drop it into the mixture of hindered amine acrylate and MMA, stir and react at room temperature for 1-60 minutes to obtain product 1, in which the total amount of MMA is equal to that of hindered amine acrylate, The ratio of the amount of diisocyanate substances is 1:(0.05-0.5):(0.025-0.25), and the amount of hindered amine acrylate substances is 2 times the amount of diisocyanate substances, and the mixed solution containing product 1 is retained, spare;

Step b: Add the initiator required for the polymerization reaction to the mixed liquid containing product 1 in step a. The amount of the initiator added is 0.1-5% of the total mass of MMA and hindered amine acrylate, and stir evenly to obtain a mixed liquid;

Step c: Degas the mixed liquid in step b, and use the vacuum-assisted infusion molding method to vacuum infuse (vacuum negative pressure is - (0.08-0.1) MPa) into the preform paved with fiber reinforced materials. At this time The preform filled with the mixed liquid is reacted (i.e., cured) at a temperature of 0-100°C for 0.1-48h, and then post-cured at 60-120°C for 0.1-48h. After demoulding and post-processing, a partially cross-linked PMMA composite is obtained. Material.

Beneficial effects of the present invention:

1. The present invention provides a method for preparing partially cross-linked PMMA. First, a polyurea reaction occurs between diisocyanate and hindered amine acrylate to generate an intermediate product (ie, product 1) containing a hindered urea group. At this time, the molecules of product 1 Both ends of the structure contain unsaturated double bonds, and then a free radical polymerization reaction occurs between the unsaturated double bonds and the MMA monomer through the initiator, and finally partially cross-linked PMMA is obtained. The long chains of the PMMA polymer are connected to each other through product 1 , so that long chains are connected through covalent bonds, that is, cross-links between long chains are formed. Compared with non-covalent bond connections between long chains of unmodified PMMA, this cross-link connection method is closer. A stable three-dimensional network structure is formed, which is conducive to improving the mechanical properties of partially cross-linked PMMA.

2. The present invention provides a method for preparing partially cross-linked PMMA. The overall steps are clear and simple, and the reaction process is controllable. First, the polyurea reaction occurs between small molecules to ensure that the polyurea reaction is complete and no by-products are produced. At the same time, the polyurea reaction is The reaction does not affect the subsequent free radical polymerization reaction, ensuring the structure of the final product - partially cross-linked PMMA; in addition, the entire reaction process uses MMA as the solvent for the polyurea reaction, and no other organic solvents are used, so in the polyurea reaction There is no need to remove the solvent at the end, and the next polymerization reaction can be carried out directly, effectively simplifying the reaction steps.

3. In the preparation method of partially cross-linked PMMA of the present invention, during the polymerization reaction, the entire reaction system contains a large amount of unreacted MMA, and the viscosity of the reaction system is low. At the same time, the polymerization reaction requires an initiator to initiate the polymerization reaction, so it has After a certain length of induction period, the vacuum-assisted infusion molding process can be directly implemented, that is, the mixed liquid containing partially cross-linked PMMA is degassed and then impregnated into the fiber-reinforced preform through vacuum infusion, and finally the fiber-reinforced resin matrix composite material is obtained, that is, Partially cross-linked PMMA composites.

4. The partially cross-linked PMMA prepared by the method of the present invention is cross-linked between its molecules through product 1, so it has a certain degree of cross-linking and has better mechanical properties than pure PMMA resin. By adjusting the amount of diisocyanate added, Its strength and toughness can be enhanced at the same time, and the tensile strength, impact strength and elongation at break can be increased to 85MPa, 33KJ/ ^m2 and 10% respectively; at the same time, the hindered urea bonds in the network of this partially cross-linked PMMA molecule are dynamic Valent chemical bonds will dissociate at high temperatures, enabling molecular healing, recycling and shape memory through the dissociation exchange mechanism, thus retaining the recyclable and reusable properties of PMMA resin. At the same time, the composite material prepared by using the partially cross-linked PMMA and fiber reinforced material of the present invention also has excellent mechanical properties, and the PMMA can also be recycled, so it is an environmentally friendly composite material.

5. The preparation method of partially cross-linked PMMA of the present invention not only has very few additives, a simple process, is green and environmentally friendly, does not use catalysts, and has a mild and controllable reaction, but also ensures that the partially cross-linked PMMA can be suitable for compounding under vacuum infusion molding processes. The preparation of the material has expanded the wide application of partially cross-linked PMMA resin in wind turbine blades, ships and yachts and other fields.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without exerting creative efforts fall within the scope of protection of the present invention.

Unless otherwise specified, the experimental methods used in the examples of the present invention are conventional methods.

Materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources unless otherwise specified.

Example 1

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1; the total moles of MMA are The ratio of the molar amount to tert-butylaminoethyl methacrylate and HDI is 1:0.05:0.025, and the mixture containing product 1 is retained for later use;

Step 2: Add the peroxide 1.0925g LPO and the reducing agent 0.4435g DMT required for the polymerization reaction to the mixed solution containing product 1 in step 1, stir until it is transparent and particle-free, and then proceed with product 1 and MMA at 25°C. Polymerization reaction, reaction time is 8 hours, and post-curing at 80°C for 3 hours, a product containing partially cross-linked PMMA is obtained.

Test the mechanical properties of the partially cross-linked PMMA prepared in this example: use the existing sample preparation method to prepare a standard test sample by pouring the mixture containing partially cross-linked PMMA in step 2, and compare the standard test strip according to the ISO international standard The tensile strength, elongation at break, and unnotched impact strength of the simply supported beam were characterized, and its mechanical properties were measured: the tensile strength was 79MPa, the impact strength was 31KJ/m ² , and the elongation at break was 9%.

Example 2

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 8.6976g MDI in 30g MMA, then slowly drop it into the mixture of 21.3064g isopropylaminoethyl methacrylate and 70g MMA, stir and react at room temperature for 20 minutes to obtain product 1, in which MMA total The molar ratio to isopropylaminoethyl methacrylate and MDI is 1:0.1:0.05, and the mixture containing product 1 is retained for later use;

Step 2: Add the peroxide 1.7776g LPO and the reducing agent 1.7412g DMA required for the polymerization reaction to the mixed solution containing product 1 in step 1. Under 40°C and anaerobic conditions, product 1 and MMA undergo a polymerization reaction. The reaction time 5h, and post-cured at 90°C for 3h to obtain a product containing partially cross-linked PMMA.

The mechanical properties of the partially cross-linked PMMA prepared in this example were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 80 MPa, the impact strength was 32 KJ/m ² , and the elongation at break was 9%.

Example 3

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 11.1008g IPDI in 25g MMA, then drop it into the mixture of 18.3028g piperidine aminoethyl acrylate and 75g MMA, stir and react at room temperature for 30 minutes to obtain product 1, in which the total molar amount of MMA and piperidine acrylate are The molar ratio of pyridine aminoethyl ester and IPDI is 1:0.1:0.05, and the mixture containing product 1 is retained for later use;

Step 2: Add the peroxide 0.2839g BPO and the reducing agent 0.1183g DMT required for the polymerization reaction to the mixed solution containing product 1 in step 1. Under -20°C and anaerobic conditions, product 1 and MMA undergo a polymerization reaction. The time was 48h and post-cured at 120°C for 1.5h to obtain a product containing partially cross-linked PMMA.

The mechanical properties of the partially cross-linked PMMA prepared in this example were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 78MPa, the impact strength was 30KJ/m ² , and the elongation at break was 8%.

Example 4

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 22.2053g IPDI in 35g MMA, then add dropwise to the mixture of 39.6020g piperidine aminoethyl methacrylate and 65g MMA, stir and react at room temperature for 50 minutes to obtain product 1, in which the total molar amount of MMA is The molar ratio with piperidine aminoethyl methacrylate and IPDI is 1:0.2:0.1, and the mixture containing product 1 is retained for later use;

Step 2: Add the peroxide 0.3282g BPO and the reducing agent 0.137g DMT required for the polymerization reaction to the mixed solution containing product 1 in step 1. Under 100°C and anaerobic conditions, product 1 and MMA undergo a polymerization reaction. The reaction time 1 h, and post-cured at 110°C for 2 h to obtain a product containing partially cross-linked PMMA.

The mechanical properties of the partially cross-linked PMMA prepared in this example were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 81 MPa, the impact strength was 32 KJ/m ² , and the elongation at break was 10%.

Example 5

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 22.2053g IPDI in 35g MMA, then add dropwise to the mixture of 39.6020g piperidine aminoethyl methacrylate and 65g MMA, stir and react at room temperature for 50 minutes to obtain product 1, in which the total molar amount of MMA is The molar ratio with piperidine aminoethyl methacrylate and IPDI is 1:0.2:0.1, and the mixture containing product 1 is retained for later use;

Step 2: Add the initiator AIBN 6.9801g required for the polymerization reaction to the mixed solution containing product 1 in step 1, polymerize product 1 and MMA at 50°C, the reaction time is 12h, and post-cure at 110°C for 2h , to obtain a product containing partially cross-linked PMMA.

The mechanical properties of the partially cross-linked PMMA prepared in this example were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 80 MPa, the impact strength was 33 KJ/m ² , and the elongation at break was 9%.

Example 6

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 43.4965g TDI in 60g MMA, then drop it into the mixture of 84.5455g tert-butylaminoethyl acrylate and 40g MMA, stir and react at room temperature for 1 minute to obtain product 1, in which the total molar amount of MMA is The molar ratio of tert-butylaminoethyl acrylate and TDI is 1:0.5:0.25, and the mixture containing product 1 is retained for later use;

Step 2: Add 0.1845g of the initiator ABVN required for the polymerization reaction to the mixed solution containing product 1 in step 1, polymerize product 1 with MMA at 30°C, the reaction time is 48h, and post-cure 0.3 at 120°C h, a product containing partially cross-linked PMMA is obtained.

The mechanical properties of the partially cross-linked PMMA prepared in this example were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 85 MPa, the impact strength was 33 KJ/m ² , and the elongation at break was 10%.

Example 7

This embodiment provides a method for preparing partially cross-linked PMMA. The steps are as follows:

Step 1: Dissolve 26.2088g HMDI in 55g MMA, then drop it into the mixture of 39.424g isopropylaminoethyl acrylate and 45g MMA, stir and react at room temperature for 60 minutes to obtain product 1, in which the total molar amount of MMA is The molar ratio of isopropylaminoethyl acrylate and HMDI is 1:0.2:0.1, and the mixture containing product 1 is retained for later use;

Step 2: Add 6.9712g of the initiator BPO required for the polymerization reaction to the mixed solution containing product 1 in step 1, polymerize product 1 and MMA at 100°C, the reaction time is 0.1h, and post-cure at 80°C After 48h, a product containing partially cross-linked PMMA was obtained.

The mechanical properties of the partially cross-linked PMMA prepared in this example were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 78MPa, the impact strength was 31KJ/m ² , and the elongation at break was 9%.

Comparative ratio

Partially cross-linked PMMA was prepared according to the method described in Example 1. The difference from Example 1 is that no HDI (i.e. no diisocyanate) was added to the reactant. 9.2521g of tert-butylaminoethyl methacrylate was added. Blended with 100g MMA, add 1.0925g LPO as peroxide and 0.4435g DMT as reducing agent, stir until there are no particles, then perform polymerization reaction at 25°C, the reaction time is 8h, and post-cure at 80°C for 3h to prepare a product containing Partially cross-linked PMMA product.

The mechanical properties of the above partially cross-linked PMMA were tested with reference to the mechanical property testing method of Example 1. The measured tensile strength was 68MPa, the impact strength was 23KJ/m ² , the elongation at break was 5%, and the three parameter values were all less than Partially cross-linked PMMA prepared in Example 1. This shows that the addition of diisocyanate in the present invention does effectively improve the tensile strength and impact strength of partially cross-linked PMMA, that is, the strength and toughness are improved.

At the same time, the partially cross-linked PMMA strips prepared in the above Examples 1-7 were broken into small pieces, and then put into a molding press, melted at 140°C, and hot-pressed to form standard test strips. This hot-pressed standard spline was tested according to ISO international standards. Compared with the properties before crushing and melting, its mechanical properties remain unchanged.

Example 8

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add the peroxide 1.0925g LPO and the reducing agent 0.4435g DMT required for the polymerization reaction to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: Degas the mixed liquid obtained in step b, use the vacuum-assisted infusion molding method, evacuate, and infuse it into a preform made of unidirectional high-alkali glass fiber cloth under a true negative pressure of -0.08MPa. , at this time, the preform filled with the mixed liquid is cured at 25°C for 8 hours, then post-cured at 80°C for 3 hours, and post-demoulding treatment is performed to obtain a partially cross-linked PMMA composite material. The surface of the unidirectional glass fiber cloth The density is 1250g/m ² , and the volume fraction of fiber reinforcement is 60%.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The 0° tensile strength of the partially cross-linked PMMA composite prepared above was 1442.3MPa and the tensile modulus was 46.5GPa.

Example 9

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add the peroxide 1.0925g LPO and the reducing agent 0.4435g DMT required for the polymerization reaction to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: After degassing the mixed liquid obtained in step b, use the method of vacuum-assisted infusion molding, evacuate, and infuse under a vacuum negative pressure of -0.09MPa until it is made of unidirectional carbon fiber cloth (specification: T700SC). In the preform, the preform filled with the mixed liquid is cured at 0℃ for 45h, then post-cured at 120℃ for 2h, and post-demoulding treatment is performed to obtain a partially cross-linked PMMA composite material, in which the volume of the fiber reinforced material The score is 60%.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The 0° tensile strength of the partially cross-linked PMMA composite prepared above was 1988.1MPa and the tensile modulus was 127.5GPa.

Example 10

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add the peroxide 0.6639g BPO and the reducing agent 0.4435g DMT required for the polymerization reaction to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: After degassing the mixed liquid obtained in step b, use the method of vacuum-assisted infusion molding, evacuate, and pour into the unidirectional basalt fiber cloth (specification: 12k-200G) under a vacuum negative pressure of -0.08MPa. In the flat preform, the preform filled with mixed liquid is cured at 40°C for 6 hours, and then post-cured at 80°C for 6 hours. After demoulding, a partially cross-linked PMMA composite material is obtained, in which fiber reinforcement The volume fraction of the material is 60%.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The 0° tensile strength of the partially cross-linked PMMA composite prepared above was 1250.5MPa and the tensile modulus was 92.8GPa.

Example 11

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add 1.0925g of the peroxide required for the polymerization reaction and 0.4435g of the reducing agent DMT to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: After degassing the mixed liquid obtained in step b, use a vacuum-assisted infusion molding method to evacuate and infuse it into a preform made of unidirectional aramid fiber cloth under a vacuum negative pressure of -0.098MPa. , at this time, the preform filled with the mixed liquid is cured at 100°C for 2 hours, then post-cured at 120°C for 1 hour, and post-demoulding treatment is performed to obtain a partially cross-linked PMMA composite material, in which the volume fraction of fiber reinforcement is 60 %.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The 0° tensile strength of the partially cross-linked PMMA composite prepared above was 506.3MPa and the tensile modulus was 29.4GPa.

Example 12

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add 1.0925g of the peroxide required for the polymerization reaction and 0.4435g of the reducing agent DMT to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: After degassing the mixed liquid obtained in step b, use the method of vacuum-assisted infusion molding, evacuate, and infuse under a vacuum negative pressure of -0.098MPa until it is made of chopped glass fiber (specification: fiber monofilament diameter 10 μm , fiber length 4mm), the preform filled with the mixed solution is cured at 100°C for 2 hours, then post-cured at 120°C for 1 hour, and post-demoulding to obtain a partially cross-linked PMMA composite material. , where the volume fraction of fiber reinforced material is 40%.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The tensile strength of the partially cross-linked PMMA composite prepared above was 98.8MPa and the tensile modulus was 3.4GPa.

Example 13

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add 1.0925g of the peroxide required for the polymerization reaction and 0.4435g of the reducing agent DMT to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: After degassing the mixed liquid obtained in step b, use the method of vacuum-assisted infusion molding, evacuate, and pour into the mixture made of glass fiber bidirectional cloth (specification: EWR600-1000, fiber In the preform paved with a monofilament diameter of 10 μm), the preform filled with the mixed liquid is cured at 100°C for 2 hours, then post-cured at 120°C for 1 hour, and post-demoulding, to obtain a partially cross-linked PMMA composite material. , where the volume fraction of fiber reinforced material is 55%.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The 0° tensile strength of the partially cross-linked PMMA composite prepared above was 261.2MPa and the tensile modulus was 9.7GPa.

Example 14

This embodiment provides a method for preparing a partially cross-linked PMMA composite material. The steps are as follows:

Step a: Dissolve 4.2182g HDI in 20g MMA, then add dropwise to the mixture of 9.2521g tert-butylaminoethyl methacrylate and 80g MMA, stir and react at room temperature for 10 minutes to obtain product 1, and retain product 1. mixture, set aside;

Step b: Add 1.0925g of the peroxide required for the polymerization reaction and 0.4435g of the reducing agent DMT to the mixed solution containing product 1 in step a, and stir until it is transparent and particle-free;

Step c: After degassing the mixed liquid obtained in step b, use a vacuum-assisted infusion molding method to evacuate and pour it into a preform paved with continuous glass fiber yarn under a vacuum negative pressure of -0.098MPa. The preform filled with the mixed liquid was cured at 100°C for 2 hours, then post-cured at 120°C for 1 hour, and post-demoulding, to obtain a partially cross-linked PMMA composite material, in which the volume fraction of fiber reinforcements was 70%.

Standard composite splines were prepared according to ISO international standards and their strength was tested. The tensile strength of the partially cross-linked PMMA composite prepared above was 705.2MPa and the tensile modulus was 26.7GPa.

From the measurement results of the mechanical property parameters of the partially cross-linked PMMA composite materials obtained in Examples 8-14, it can be seen that the fiber-reinforced partially cross-linked PMMA composite material prepared by the vacuum-assisted infusion molding method has excellent mechanical properties; at the same time, the PMMA in the composite material The resin can be recycled and reused through solvent dissolution, and fiber reinforcements can also be reused, such as in the preparation of composite materials.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims (9)

1. A method for preparing partially cross-linked PMMA, which is characterized in that the preparation steps are as follows: (1) Dissolve the diisocyanate into MMA, then drop it into the mixture of hindered amine acrylate and MMA, stir and react at room temperature for 1 to 60 minutes, and obtain product 1. Keep the mixture containing product 1 for later use; (2) Add the initiator required for the polymerization reaction to the mixed solution containing product 1 in step (1) and mix. Under certain conditions, product 1 and MMA undergo a polymerization reaction to obtain partially cross-linked PMMA; The ratio of the total amount of MMA substances to the amount of hindered amine acrylate and diisocyanate substances is 1: (0.05~0.5): (0.025~0.25), wherein the amount of hindered amine acrylate substances is diisocyanate substances 2 times the amount; the added amount of the initiator is 0.1~5% of the total mass of MMA and hindered amine acrylate. 2. The preparation method of partially cross-linked PMMA according to claim 1, characterized in that: the diisocyanate is any one of IPDI, HDI, TDI, MDI and HMDI; the hindered amine acrylate is methyl In tert-butylaminoethyl acrylate, tert-butylaminoethyl acrylate, isopropylaminoethyl methacrylate, isopropylaminoethyl acrylate, piperidine aminoethyl acrylate and piperidine aminoethyl methacrylate Any of; the initiator is a thermal decomposition initiator and/or a redox initiator; the thermal decomposition initiator is an azo compound and/or a peroxy compound; the redox initiator is a combination of a peroxide and a reducing agent combination. 3. The preparation method of partially cross-linked PMMA according to claim 1, characterized in that the polymerization reaction conditions in step (2) are: after reacting at -20~100°C for 0.1~48h, then at 60 Post-cure at ~120°C for 0.1~48h. 4. Partially cross-linked PMMA prepared by the method of any one of claims 1-3. 5. A partially cross-linked PMMA composite material, characterized in that: the partially cross-linked PMMA composite material contains the partially cross-linked PMMA as claimed in claim 4 and fiber reinforcement. 6. The partially cross-linked PMMA composite material according to claim 5, characterized in that: the fiber reinforcement material is chopped fiber or continuous fiber; the chopped fiber is chopped carbon fiber, chopped glass fiber, chopped aramid fiber and chopped high-density polyethylene fiber; continuous fiber is one or more of carbon fiber, glass fiber, basalt fiber and aramid fiber. 7. The preparation method of partially cross-linked PMMA composite material according to claim 5, characterized in that: the preparation method is an injection molding method, a vacuum-assisted infusion molding method, a compression molding method, a winding molding method and a pultrusion molding method. any kind. 8. The preparation method of partially cross-linked PMMA composite material according to claim 7, characterized in that the step of the vacuum-assisted infusion molding method is: adding a product with an initiator in step (2) of claim 1 The mixed liquid in 1 is degassed, and the vacuum-assisted infusion molding method is used. Vacuum infusion is carried out into a preform paved with fiber reinforced materials, and then through curing reaction, demoulding and post-processing, a partially cross-linked PMMA composite material is obtained. 9. The method for preparing a partially cross-linked PMMA composite material according to claim 8, characterized in that: the vacuum negative pressure of the vacuum infusion is -(0.08~0.1)MPa; the curing reaction conditions are first curing at a temperature of 0~100°C for 0.1~48h, and then post-curing at a temperature of 60~120°C for 0.1~48h.