CN110483716B

CN110483716B - In-situ self-reinforced polyimide composite material and preparation method thereof

Info

Publication number: CN110483716B
Application number: CN201910766501.3A
Authority: CN
Inventors: 梁嵩; 冯帆; 白成琨; 刘镇宁; 秦政; 王冰迪; 王志达
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2019-08-20
Filing date: 2019-08-20
Publication date: 2021-04-27
Anticipated expiration: 2039-08-20
Also published as: CN110483716A

Abstract

An in-situ self-reinforced polyimide composite material covalently connected through imine bonds and a preparation method thereof belong to the technical field of composite materials. Dissolving aminosilane, dialdehyde and diamine in isopropanol or ethanol solvent, uniformly stirring, and then heating at 55-65 ℃ for 72-120 hours to obtain polyimide; and (3) crushing the mixture into powder, sieving the powder by using a sieve of 80-120 meshes, and then carrying out hot pressing at 80-95 kPa and 60-70 ℃ for 55-110 min for molding to obtain the in-situ self-reinforced polyimide composite material. The method utilizes raw materials with different proportions to adjust so as to synthesize the polyimide material, imine bond covalence is formed in the polyimide material through an imine double decomposition reaction of dynamic covalent chemistry, and the added aminosilane can be used as a cross-linking agent to form a silicon dioxide inorganic enhanced phase, so that the mechanical property of the material is further improved, and the in-situ self-enhanced polyimide composite material with certain mechanical property is obtained.

Description

In-situ self-reinforced polyimide composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of composite materials, and particularly relates to an in-situ self-reinforced polyimide composite material covalently connected through imine bonds and a preparation method thereof.

Background

The plastics widely used at present are mainly divided into two types, thermosetting plastics and thermoplastic plastics, wherein thermosetting plastics have good mechanical strength and physical and chemical properties, but cannot be recycled. Thermoplastics can be processed and used repeatedly, but have great disadvantages in terms of mechanical properties. Therefore, the material which can be repeatedly processed and utilized and has certain mechanical property has wide application prospect.

The chinese patent CN 104788911a prepares the epoxy resin composite material with high thermal conductivity and low viscosity by dispersing inorganic filler in the epoxy resin, but in the preparation process, a curing agent needs to be added, the preparation process is complex, the temperature is high, and the time is long. Chinese patent CN 104130509A discloses a preparation method of a strong-viscosity crosslinking material with high viscosity, low density, high strength, low heat generation and contraction-rebound memory toughness, but a crosslinking agent is required to be added in the preparation process. Chinese patent CN 104356505A discloses a method for preparing a light universal plastic composite material with large industrial solid waste filling amount, low density, good mechanical property and strong impact resistance, however, the preparation process needs high temperature and a coupling agent, and various additive materials can not be mixed according to any proportion, and the adjustability is low.

Therefore, although the existing composite materials are prepared by a plurality of methods, the synthesis method has some problems, such as the addition of a cross-linking agent and a catalyst in some preparation processes, the adjustability of different composition ratios of most composite materials in the preparation process is low, even if some composite material components are connected by chemical bonds, a coupling agent is still needed among all phases, and the like, so that the preparation process is complex, the temperature is too high, and the time is long.

Disclosure of Invention

The invention aims to develop an in-situ self-reinforced polyimide composite material which is connected by covalent bonds, can be adjusted in mixing ratio, does not need an additional adhesive, can be processed and molded in a green way and can generate an inorganic reinforced phase in situ and a preparation method thereof.

The invention utilizes the dialdehyde and diamine to prepare the polyimide material which is different from polyamide, polyimide and polyurethane, the amido (or imino) in the polyamide, polyimide and polyurethane is connected with acyl through carbon-nitrogen single bond, which has high chemical stability and can not generate double decomposition exchange reaction. The polymer chains of the polyimide composite material prepared by the method are connected through carbon-nitrogen double bonds, can generate dynamic covalent chemical imine double decomposition reaction at 60-70 ℃, and has low-temperature plasticity. The method utilizes raw materials with different proportions to adjust and synthesize the polyimide material, forms imine bond covalent connection through the imine double decomposition reaction of dynamic covalent chemistry, and the added amino silane can be used as a cross-linking agent, wherein an inorganic enhanced phase is formed, and the polyimide composite material with certain mechanical property can be obtained under the condition of low-temperature hot pressing.

The invention relates to a method for preparing an in-situ self-reinforced polyimide composite material through imine bond covalent connection, which uses amino silane to replace the traditional cross-linking agent and comprises the following steps:

(1) aminosilane (silane compound with primary amine group including but not limited to 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane, 3-aminopropyldiethoxymethylsilane, 3- (2-aminoethyl methyl) propyldimethoxymethylsilane, 3- (2-aminoethyl methyl) propyltrimethoxysilane, 3- (2-aminoethyl methyl) propyltriethoxysilane, [3- (6-aminohexylmethyl) propyl) trimethoxysilane, etc.), dialdehyde (aliphatic dialdehyde including but not limited to glutaraldehyde, hexandialdehyde, heptadialdehyde, etc., and dialdehyde derivative with side chain thereof, such as aromatic dialdehyde including terephthalaldehyde, o-phthalaldehyde, m-phthalaldehyde, etc.), diamine (including but not limited to diethylenetriamine, di-allyltrimethoxysilane, etc.), Dissolving N, N-bis (2-aminoethyl) -1, 3-propanediamine and the like) in isopropanol or ethanol solvent, uniformly stirring, and then heating at 55-65 ℃ for 72-120 hours to obtain polyimide; wherein the molar ratio of dialdehyde to aminosilane to diamine is 2.000: (1.000-1.750): (1.500-1.125);

(2) crushing the polyimide obtained in the step (1) into powder, and sieving the powder by a sieve of 80-120 meshes;

(3) and (3) carrying out hot pressing on the polyimide powder obtained in the step (2) at 80-95 kPa and 60-70 ℃ for 55-110 min for molding, thus obtaining the in-situ self-reinforced polyimide composite material.

Drawings

FIG. 1: the in-situ self-reinforced polyimide composite material prepared in example 1 (a product corresponding to the third row of data in table 1) has different treatment modes (hot pressing and non-hot pressing) and infrared spectra of raw materials; unned represents the sample without autoclave treatment, Cured represents the sample with autoclave treatment, and APTMS, GA and DETA represent 3-aminopropyltrimethoxysilane, glutaraldehyde and diethylenetriamine respectively.

FIG. 2: the X-ray diffraction pattern of the in situ self-reinforced polyimide composite prepared in example 1 (the product corresponding to the third row data in table 1);

FIG. 3: optical photographs of the in situ self-reinforced polyimide composite (the product corresponding to the third row of data in table 1) prepared in example 1, the sample on the right side is a sample prepared without repeated pulverization and hot pressing, and the sample on the left side is a sample prepared by repeated pulverization and hot pressing.

FIG. 4: tensile curves for 8 in situ self-reinforced polyimide composites prepared in example 1;

FIG. 5: tensile modulus scatter plots of 8 in situ self-reinforced polyimide composites prepared in example 1;

FIG. 6: tensile toughness scatter plots of 8 in situ self-reinforced polyimide composites prepared in example 1;

FIG. 7: a scatter plot of elongation at break for 8 in situ self-reinforced polyimide composites prepared in example 1;

FIG. 8: tensile strength scatter plots of 8 in situ self-reinforced polyimide composites prepared in example 1;

FIG. 9: tensile curves of the 4 reheat pressed in situ self-reinforced polyimide composites prepared in example 2;

FIG. 10: tensile modulus scatter plots of 4 in situ self-reinforced polyimide composites prepared in example 2, reheated 1,3, 5, 7 times;

FIG. 11: tensile toughness scatter plots of 4 in-situ self-reinforced polyimide composites prepared in example 2, reheated 1,3, 5, 7 times;

FIG. 12: breaking elongation scatter plots of 4 in-situ self-reinforced polyimide composite materials prepared in example 2, reheated 1,3, 5 and 7 times;

FIG. 13: tensile strength scatter plots of 4 in situ self-reinforced polyimide composites prepared in example 2, reheated 1,3, 5, 7 times.

Detailed Description

Example 1

(1) The following series of materials were obtained

Original polyimide material: dissolving 75.6mL (0.4mmol) of glutaraldehyde in 100mL of isopropanol to obtain a methyl solution, and dissolving diethylenetriamine and 3-aminopropyltrimethoxysilane (a cross-linking agent) in the amount proportion shown in Table 1 in 100mL of isopropanol to obtain an ethyl solution; respectively and magnetically stirring and uniformly mixing the solution A and the solution B, dropwise adding the solution B into the solution A, stirring simultaneously, and after 5min, moving the container into a 60 ℃ oven for heating treatment for 96 hours to obtain a solid polyimide material (except the first row ratio);

table 1: experimental data for Polyimine prepolymers with different monomer ratios

(2) Crushing the original polyimide material solid obtained in the step (1) into powder, and sieving the powder with a 80-mesh sieve;

(3) 0.8g of the sample (the product of the raw material ratio shown in the second row to the ninth row in the table 1) is weighed respectively, and hot-pressed for 60min at 9MPa and 60 ℃ to prepare 8 in-situ self-reinforced polyimide composite materials with different raw material ratios, wherein the obtained composite materials are sheets of 40mm multiplied by 10mm multiplied by 1 mm.

(4) And (4) carrying out infrared detection comparison on the composite material powder obtained in the step (3) and the powder with the same components obtained without hot pressing treatment.

As shown in FIG. 1, the infrared spectrum of the infrared spectrum is 1637cm, following the autoclave of the polyimide composite preparation process^-1The absorption peak is greatly enhanced, and in the prepared polyimide material, the functional group of partial monomer is contained and 1033cm is increased^-1Imine bond at (b). At the same time, as can also be seen from FIG. 2, inThe polyimide powder obtained contains amorphous silica. Further, as can be seen from fig. 3, in the molding range, the color of the composite sheet obtained by subjecting the sample to the reheat pressing treatment after the repeated processing becomes darker, and the internal unevenness is caused by the continuous processing from the sample having good transparency to the polyimide sample having poor light transmittance. In summary, covalent linkage is formed in the polyimide material through an imine double decomposition reaction, and a silica reinforced phase is formed, so that the mechanical property of the material is further improved, and the in-situ self-reinforced polyimide composite material with certain mechanical property is obtained.

Example 2

Respectively crushing the 8 in-situ self-reinforced polyimide composite materials (products in the lines 2 to 9 in the table 1) obtained in the example 1 into powder, and sieving the powder by a 80-mesh sieve; respectively weighing 0.80g of polyimide material powder, placing the polyimide material powder into a die, and flattening the surface of the powder; and then hot-pressing for 60min under the conditions of 90kPa and 60 ℃ for molding, thus obtaining the in-situ self-reinforced polyimide composite material again, wherein the obtained composite material is a sheet of 40mm multiplied by 10mm multiplied by 1 mm. The mechanical performance of a series of polyimide composite materials prepared by the operations of crushing and hot pressing for a plurality of times is tested, and the test results are shown in table 2. The result shows that the product prepared by any raw material proportion can be molded, good hardness and tensile strength can be maintained, the tensile elastic modulus is increased along with the increase of the addition amount of the cross-linking agent, and the stress-strain relationship follows a certain rule.

Table 2: ABSE-Pi and reworked ABSE-Pi mechanical property integrity test data

The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A preparation method of an in-situ self-reinforced polyimide composite material comprises the following steps:

(1) dissolving aminosilane, dialdehyde, diethylenetriamine or N, N-bis (2-aminoethyl) -1, 3-propane diamine in isopropanol or ethanol solvent, uniformly stirring, and then heating at 55-65 ℃ for 72-120 hours to obtain polyimide; wherein, the molar ratio of dialdehyde, amino silane and diethylenetriamine or N, N-bis (2-aminoethyl) -1, 3-propane diamine is 2.000: (1.000-1.750): (1.500-1.125);

(3) and (3) hot-pressing the polyimide powder obtained in the step (2) for 60min at the temperature of 60 ℃ under 9MPa to form the in-situ self-reinforced polyimide composite material.

2. The method of claim 1, wherein the in situ self-reinforced polyimide composite material is prepared by the following steps: the aminosilane is 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldimethoxymethylsilane or 3-aminopropyldiethoxymethylsilane.

3. The method of claim 1, wherein the in situ self-reinforced polyimide composite material is prepared by the following steps: the dialdehyde is glutaraldehyde, hexanedial, heptanedial, terephthalaldehyde, o-phthalaldehyde or m-phthalaldehyde.

4. An in-situ self-reinforced polyimide composite material, which is characterized in that: is prepared by the method of any one of claims 1 to 3.