CN115873249A

CN115873249A - Plasma-treated fiber-reinforced polyimide material and preparation method thereof

Info

Publication number: CN115873249A
Application number: CN202211678316.7A
Authority: CN
Inventors: 查道鑫; 刘一修; 韩路遥
Original assignee: Huangshan Jinshimu Plastic Technology Co ltd
Current assignee: Huangshan Jinshimu Plastic Technology Co ltd
Priority date: 2022-12-26
Filing date: 2022-12-26
Publication date: 2023-03-31

Abstract

The invention relates to a plasma-treated fiber-reinforced polyimide material and a preparation method thereof, belonging to the technical field of polyimide composite materials and comprising the following preparation steps: adding a solvent and a plasma into a flask for treating fibers for the first time, adding a first monomer and a second monomer at room temperature, mechanically stirring under the protection of nitrogen until the first monomer and the second monomer are completely dissolved, adding 3,3',4,4' -biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride in batches, stirring for reaction at room temperature, adding a terminal blocking agent, stirring for reaction, supplementing the solvent, and stirring to obtain a terminal-blocked polyamic acid solution; and then adding acetic anhydride and triethylamine to carry out imidization reaction, then transferring the mixture to an ethanol solution for precipitation, carrying out suction filtration, washing and drying to obtain the plasma-treated fiber-reinforced polyimide material.

Description

Plasma-treated fiber-reinforced polyimide material and preparation method thereof

Technical Field

The invention belongs to the technical field of polyimide composite materials, and particularly relates to a plasma-treated fiber-reinforced polyimide material and a preparation method thereof.

Background

The polyimide resin material has high strength and excellent high/low temperature resistance and the like, is an excellent representative of high-performance polymer materials, but can meet the use requirement after being enhanced by additives/modifiers in certain specific use fields. The fiber reinforced thermosetting polyimide resin-based composite material has the advantages of light weight, excellent mechanical property and the like, and is widely applied to the industrial fields of aerospace, automation and the like.

In journal 2018 of aeronautical manufacturing technology, 61 (14) of "chopped carbon fiber reinforced polyimide composite performance" DOI, 10.16080/j.issn1671-833x.2018.14.079, a die pressing process is adopted to prepare the chopped carbon fiber reinforced thermosetting polyimide composite material by taking carbon fibers as additives, and the final result shows that the linear expansion coefficient of the chopped carbon fiber reinforced thermosetting polyimide composite material is reduced along with the increase of the volume fraction of chopped fibers, the tensile modulus, the compression modulus and the bending modulus are increased along with the increase of the volume fraction of the chopped fibers, the tensile strength and the bending strength are reduced after being increased, and the compression strength has the tendency of slowly increasing along with the volume fraction of the fibers.

Functional material 2019,6 (50) fatigue characteristics of quartz fiber reinforced polyimide resin-based composite material doi: 10.3969/j.issn.1001-9731.2019.06.014A reports that the quartz fiber reinforced polyimide resin matrix composite material has the advantages of high specific strength, large specific stiffness, designability of structure and the like, the room temperature and high temperature tensile properties of the quartz fiber reinforced polyimide resin matrix composite material are discussed, and the room temperature and high temperature tensile-tensile fatigue properties of the material are researched. The results show that the fatigue life of the composite material is higher under the room temperature condition.

Li Luying, university of Jiangsu, academic thesis in 2018, namely preparation of carbon fiber cloth reinforced polyimide-based composite material and research on mechanical and tribological properties of the composite material, a chapter of the preparation method utilizes continuity of Carbon Fibers (CF) to improve dispersibility and stress transfer of a reinforcing phase in a Polyimide (PI) matrix, and simultaneously utilizes high activity characteristics of dopamine to covalently graft a polydopamine (p-phenylenediamine) molecular layer on the surface of the CF. Abundant amino and hydroxyl functional groups are introduced into CF by p-phenylenediamine, so that the surface activity of the CF is enhanced, the CF and a PI matrix are subjected to covalent crosslinking, and the interface compatibility of the matrix and fibers in the p-phenylenediamine-CF/PI composite material is improved. Stress and heat are continuously transmitted and timely dissipated along the extending direction of the CF. The results prove that the heat conduction, the mechanical property and the friction property of the p-phenylenediamine-CF/PI composite material are obviously improved.

In the prior preparation process of the fiber reinforced polyimide composite material, whether the fiber is directly added as a filler during early synthesis or the polyimide resin is physically mixed with the fiber afterwards, the performance of the fiber reinforced polyimide composite material has certain bottleneck, and the fiber is usually required to be pretreated.

The prior pretreatment methods comprise: the method comprises the modes of acid etching treatment, chemical grafting treatment, plasma treatment and the like, wherein the acid etching treatment has poor broad spectrum, and different etching solutions are required to be adopted for different fibers; the chemical grafting treatment steps are complicated, the consumed time is long, and the industrial growth is not facilitated; the plasma treatment adopts a plasma cleaner (also called a plasma cleaner or a plasma surface treatment instrument) to complete cleaning and decontamination, improves the surface performance of the material (such as improving the surface wettability and the film adhesion) and has specific broad spectrum, so that the fiber can be treated with different materials, and the fiber is suitable for industrial production.

However, in the process of plasma treatment of the fiber, the selection of the cleaning degree is closely related to the performance of the material, and for the fiber reinforced polyimide composite material, the fiber subjected to plasma cleaning treatment is not suitable for over-cleaning, and over-long cleaning time may cause a compact cross-linked layer to be formed on the surface of the material, so that physical or chemical changes occur on the surface of the material, that is, the over-cleaning treatment damages the surface base energy of the material, and the overall performance of the material is reduced.

Therefore, it is necessary to provide a better plasma-treated fiber-reinforced polyimide material and a preparation method thereof.

Disclosure of Invention

The invention aims to provide a plasma-treated fiber-reinforced polyimide material and a preparation method thereof, which solve the technical problems in the prior art.

The purpose of the invention can be realized by the following technical scheme:

a preparation method of a plasma-treated fiber-reinforced polyimide material comprises the following steps:

adding a solvent into a flask for the first time, adding a plasma treated fiber, adding a first monomer and a second monomer under the room temperature condition, mechanically stirring until the first monomer and the second monomer are completely dissolved under the protection of nitrogen, slowly adding 3,3',4,4' -biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride in batches, stirring and reacting for 12 hours at the room temperature at the rotating speed of 300-500r/min, then adding a blocking agent, stirring and reacting for 6 hours, supplementing the solvent in the period, stirring for 11.5-12.5 hours to obtain a polyamide acid solution after blocking, then adding acetic anhydride and triethylamine for imidization, transferring the mixture after reacting for 20 hours to a mixed solution consisting of deionized water and absolute ethyl alcohol for precipitation, carrying out suction filtration, washing a filter cake, and carrying out vacuum drying at the temperature of 150 ℃ under the pressure of-0.095 MPa for 3-5 hours to obtain the plasma treated fiber reinforced polyimide material.

Further, the dosage ratio of the primary solvent, the plasma treated fiber, the first monomer, the second monomer, 3,3',4,4' -biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride, the end capping agent, the supplementary solvent, acetic anhydride and triethylamine is 500-600mL:18-50g:0.25mol:0.025mol:8.0g:53.9g:0.2g:100-200mL:60mL of: 30mL.

Further, the plasma treated fiber is made by the steps of:

placing the fiber material in a plasma cleaning cavity, vacuumizing the cavity to the limit vacuum by adopting a vacuum pump, introducing a cleaning medium to ensure that the vacuum degree in the cleaning cavity is 50-100Pa, turning on a power supply, and cleaning for 5min at the frequency of 40kHz-13.56MHz to obtain the plasma treated fiber.

Further, the fiber material is glass fiber or carbon fiber, and the cleaning medium is one or two of argon and helium.

Further, the solvent is one of N, N-dimethylacetamide, N-dimethylacetamide and N-methylpyrrolidone.

Further, the first monomer is one of 4,4 '-diaminodiphenyl ether, 4,4' -bis (4-aminophenoxy) biphenyl and 3,3',5,5' -tetramethylbenzidine.

Further, the second monomer is p-phenylenediamine or 4,4' -diaminodiphenyl ether.

Further, the end capping agent is 4-phenylethynyl phthalic anhydride.

Further, the volume ratio of the deionized water to the absolute ethyl alcohol in the mixed solution consisting of the deionized water and the absolute ethyl alcohol is 5-6:3-7.

Further, a plasma-treated fiber-reinforced polyimide material is prepared by the preparation method.

The invention has the beneficial effects that:

1. according to the invention, the fibers are cleaned by adopting the plasma, so that impurities on the surfaces of the fibers can be effectively removed, the surface performance of the material can be improved, the surface wettability can be improved, the adhesion force can be improved, the fibers and the polyimide resin have good adhesion, and the overall performance of the composite material can be improved.

2. The invention really realizes the optimal time for treating the fiber by the plasma through a systematic experimental means, improves the treatment effect while ensuring the working efficiency, and avoids the phenomenon that the performance of the fiber and polyimide resin composite material is influenced by a compact cross-linking layer formed on the surface of the fiber material due to over-treatment.

3. The invention compares the performance of the composite material formed by the plasma-treated fiber and the polyimide resin which is not subjected to the plasma treatment, and the result proves that the performance of the polyimide resin composite material formed by the plasma-treated fiber is obviously improved under the same condition.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a microscopic morphology of a carbon fiber of comparative example 1 of the present invention;

FIG. 2 is a microscopic topography of the plasma treated carbon fiber prepared in example 1 of the present invention;

fig. 3 is a structural view of the plasma-treated fiber reinforced polyimide materials prepared in example 5 of the present invention and comparative example 5.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Comparative example 1

This comparative example is a commercially available carbon fiber. The microscopic morphology of the carbon fibers was observed as shown in fig. 1.

Example 1

Plasma treatment of the fiber:

and (3) putting 30g of carbon fiber into a plasma cleaning cavity, vacuumizing the cavity to the limit vacuum by using a vacuum pump, introducing argon to ensure that the vacuum degree of the cavity is 60Pa, then opening a power supply, cleaning for 5min at the frequency of 40kHz, and immediately transferring into a reaction flask after cleaning to obtain the plasma treated fiber.

The microscopic morphology observation of the plasma treated fiber shows that the surface smoothness and the dispersibility of the carbon fiber after the plasma treatment are obviously improved as shown in figure 2.

Comparative example 2

This comparative example is a commercially available glass fiber.

Example 2

Plasma treatment of the fiber:

and (3) putting 30g of glass fiber in a plasma cleaning cavity, vacuumizing to the limit vacuum by using a vacuum pump, introducing helium to ensure that the vacuum degree of the cavity is 80Pa, then, turning on a power supply, cleaning for 5min at the frequency of 13.56MHz, and immediately transferring into a reaction flask after cleaning to obtain the plasma treated fiber.

Comparative example 21

Compared with example 2, the cleaning time is adjusted to 10min for 5min, and the rest raw materials and preparation process are the same as example 2.

Comparative example 22

Compared with example 2, the cleaning time is adjusted to 30min for 5min, and the rest raw materials and preparation process are the same as example 2.

Example 3

Plasma treatment of the fiber:

and (2) putting 60g of glass fiber into a plasma cleaning cavity, pumping the cavity to the limit vacuum by using a vacuum pump, introducing argon to ensure that the vacuum degree in the cavity is 50Pa, then introducing helium to ensure that the vacuum degree in the cavity is 100Pa, then turning on a power supply, cleaning for 5min at the frequency of 40kHz, and immediately transferring into a reaction flask after cleaning to obtain the plasma treated fiber.

Example 4

Respectively adding 500mL of N, N-dimethylacetamide into a 1000mL glass flask, respectively adding 18g of the plasma treated fiber obtained in the above example 1 into the flask, respectively adding 50.06g of 4,4' -diaminodiphenyl ether and 2.7g of p-phenylenediamine at room temperature, protecting in nitrogen atmosphere, mechanically stirring until the two substances are completely dissolved, slowly adding 8.0g of 3,3',4,4' -biphenyl tetracarboxylic dianhydride and 53.90g of pyromellitic dianhydride in two batches at an interval of 10min, wherein the two additions are the same, stirring at room temperature and at the speed of 300r/min for 12h, then adding 0.2g of 4-phenylethynyl phthalic anhydride, stirring for 6h, adding 100100 mL of N-dimethylacetamide during the stirring, and adding 11.5h of end capping reagent to obtain a polyamic acid solution after end capping; and then adding 60mL of acetic anhydride and 30mL of triethylamine for imidization, reacting for 20h, precipitating in a mixed solution of water and ethanol, carrying out suction filtration, washing a filter cake, and carrying out vacuum drying at the temperature of 150 ℃ and the pressure of-0.095 MPa for 3h to obtain the plasma-treated fiber-reinforced polyimide material.

Wherein the volume ratio of the deionized water to the absolute ethyl alcohol in the mixed solution consisting of the deionized water and the absolute ethyl alcohol is 5:3.

example 5

Adding 500mL of N, N-dimethylacetamide into a 1000mL quartz flask, adding 25g of the plasma treated fiber obtained in example 2 into the flask respectively, adding 2.7g of p-phenylenediamine and 92.10g of 4,4' -bis (4-aminophenoxy) biphenyl under room temperature conditions, mechanically stirring until the substances are completely dissolved under nitrogen protection, slowly adding 8.0g of 3,3',4,4' -biphenyl tetracarboxylic dianhydride and 53.90g of pyromellitic dianhydride in equal amount in two batches, wherein the two batches are separated by 10min, and the two batches are added in the same amount, violently stirring and reacting for 12h at room temperature, then adding 0.2g of 4-phenylethynyl phthalic anhydride, reacting for 6h, adding 150mL of N, N-dimethylacetamide during the reaction, and stirring for 12h to obtain a polyamic acid solution capped by a capping agent; adding 60mL of acetic anhydride and 30mL of triethylamine for imidization, reacting for 20h, precipitating in a mixed solution of water and ethanol, filtering, washing a filter cake, and drying in vacuum at 150 ℃ and-0.095 MPa for 4h to obtain the plasma-treated fiber-reinforced polyimide material.

Wherein the volume ratio of the deionized water to the absolute ethyl alcohol in the mixed solution consisting of the deionized water and the absolute ethyl alcohol is 5:5.

the resulting plasma-treated fiber-reinforced polyimide material was pressed into a plate and the surface was observed as shown in the right drawing of fig. 3.

Example 6

Adding 600mL of N-methylpyrrolidone into a 1000mL quartz flask, adding 50g of the plasma-treated fiber obtained in example 2 into the flask respectively, adding 5.0g of 4,4' -diaminodiphenyl ether and 60.08g of 3,3',5,5' -tetramethylbenzidine at room temperature, protecting by nitrogen atmosphere, mechanically stirring until the two substances are completely dissolved, slowly adding 8.0g of 3,3',4,4' -biphenyltetracarboxylic dianhydride and 53.90g of pyromellitic dianhydride in equal amount in two batches, wherein the two batches are separated by 10min, violently stirring and reacting for 12h at room temperature, adding 0.2g of 4-phenylethynylphthalic anhydride and reacting for 6h, adding 200mL of N-methylpyrrolidone during the reaction, stirring for 12h to obtain a polyamide acid solution after end capping by an end capping agent, adding 60mL of acetic anhydride and 30mL of triethylamine, imidizing the polyamide acid solution after reacting for 20h, precipitating in a mixed solution of water and ethanol, washing at 150 MPa, vacuum drying a filter cake at 0.095-5 h, and drying to obtain a polyimide reinforced polyimide material.

Wherein the volume ratio of the deionized water to the absolute ethyl alcohol in the mixed solution consisting of the deionized water and the absolute ethyl alcohol is 6:7.

comparative example 4

Compared with example 4, the plasma treated fiber in example 4 was replaced by the carbon fiber in comparative example 1, and the rest of the raw materials and the preparation process were the same as in example 4.

Comparative example 5

Compared with example 5, the plasma treated fiber in example 5 is replaced by the glass fiber in comparative example 2, and the rest of the raw materials and the preparation process are the same as example 5.

The obtained plasma-treated fiber-reinforced polyimide material was pressed into a plate, and the surface was observed, as shown in the left diagram of fig. 3, it was found that the surface of the plate prepared in example 5 was more bright and flat and the color was lighter.

Comparative example 51

In comparison with example 5, the plasma-treated fiber of example 5 was replaced with the glass fiber of comparative example 21, and the remaining raw materials and preparation process were the same as those of example 5.

Comparative example 52

Compared with example 5, the plasma treated fiber in example 5 was replaced by the glass fiber in comparative example 22, and the rest of the raw materials and the preparation process were the same as example 5.

Comparative example 6

Compared with example 6, the plasma treated fiber in example 6 was replaced by the glass fiber in comparative example 2, and the rest of the raw materials and the preparation process were the same as example 6.

The plasma-treated fiber-reinforced polyimide materials prepared in comparative examples 4 to 6, comparative example 51, comparative example 52 and examples 4 to 6 were subjected to heat preservation and pressure holding for 2 hours at a plate temperature of 420 ℃ under a pressure of 40MPa by using a 100T four-column press vulcanizer, and then to performance tests, in which tensile strength and elongation at break were measured according to reference standard GB/T1040.1-2008, flexural strength was measured according to reference standard GB/T9341-2008, unnotched impact strength was measured according to reference standard GB/T1043.1-2008, and hardness was measured according to reference standard GB/T3398.2-2008, and the test results are shown in table 1:

TABLE 1

It can be seen from table 1 that compared with the comparative examples, the fiber reinforced polyimide materials prepared in examples 4 to 6 have higher performance, because the surface activity of the fiber is increased by reasonably controlling the cleaning time of the plasma and the treatment of different media, which is beneficial to improving the overall performance of the composite material;

it can be seen from the comparison of the experimental data of example 5, comparative example 51 and comparative example 52 that as the plasma cleaning time increases, the exposure time of the material to be cleaned in the plasma has a great influence on its surface cleaning effect and on the contribution of the composite material performance.

With the deep exposure of the cleaning process, the organic matter pollution on the surface of the substance to be cleaned and the surface containing trace oxide layer are subjected to chemical impact, the pollutants are partially evaporated in a vacuum state, and the pollutants are crushed and vacuumized under the impact of high-energy ions. The plasma cleaning is just an obvious characteristic, so that organic pollutants on the surface of the fiber are cleaned firstly in the cleaning process of the fiber of the system, then an oxide layer is cleaned, and with the deepening of the cleaning process and the prolonging of the cleaning time, the high-energy ions clean the organic matters and the oxides on the surface of the fiber and then continue to treat the surface of the fiber, and the high-energy ions cause certain damage to the surface of the fiber under the long-time action and impact, so that the comprehensive mechanical property of the composite material is obviously reduced;

therefore, the cleaning time is controlled to be 5min as the optimal choice, so that the working efficiency is ensured, and the phenomenon that the performance of the fiber and polyimide resin composite material is influenced due to the formation of a compact cross-linked layer on the surface of the fiber material caused by over-treatment is avoided.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.

Claims

1. A preparation method of a fiber reinforced polyimide material treated by plasma is characterized by comprising the following steps:

adding a solvent and a plasma into a flask for treating fibers for the first time, adding a first monomer and a second monomer at room temperature, mechanically stirring under the protection of nitrogen until the first monomer and the second monomer are completely dissolved, adding 3,3',4,4' -biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride, stirring for reacting for 12 hours, adding a terminal-blocking agent, stirring for reacting for 6 hours, supplementing the solvent during the reaction, and stirring for 11.5-12.5 hours to obtain a terminated polyamic acid solution;

and then adding acetic anhydride and triethylamine, reacting for 20h, transferring to a mixed solution consisting of deionized water and absolute ethyl alcohol for precipitation, performing suction filtration, washing a filter cake, and performing vacuum drying at the temperature of 150 ℃ and the pressure of-0.095 MPa for 3-5h to obtain the plasma-treated fiber reinforced polyimide material.

2. The method for preparing a plasma-treated fiber-reinforced polyimide material according to claim 1, wherein the amount ratio of the primary solvent, the plasma-treated fiber, the first monomer, the second monomer, 3,3',4,4' -biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, the capping agent, the supplementary solvent, acetic anhydride, and triethylamine is 500-600mL:18-50g:0.25mol:0.025mol:8.0g:53.9g:0.2g:100-200mL:60mL of: 30mL.

3. The method of claim 1, wherein the plasma treated fiber is made by the steps of:

placing the fiber material in a plasma cleaning cavity, vacuumizing the cavity to the limit vacuum by using a vacuum pump, introducing a cleaning medium to ensure that the vacuum degree in the cleaning cavity is 50-100Pa, and cleaning for 5min at the frequency of 40kHz-13.56MHz to obtain the plasma treated fiber.

4. The method of claim 3, wherein the fiber material is glass fiber or carbon fiber.

5. The method of claim 3, wherein the cleaning medium is one or both of argon and helium.

6. The method of claim 1, wherein the solvent is one of N, N-dimethylacetamide, N-dimethylacetamide and N-methylpyrrolidone.

7. The method of claim 1, wherein the first monomer is one of 4,4 '-diaminodiphenyl ether, 4,4' -bis (4-aminophenoxy) biphenyl, and 3,3',5,5' -tetramethylbenzidine.

8. The method of claim 1, wherein the second monomer is p-phenylenediamine or 4,4' -diaminodiphenyl ether.

9. The method of claim 1, wherein the end-capping agent is 4-phenylethynyl phthalic anhydride.

10. A plasma-treated fiber-reinforced polyimide material, which is obtained by the production method according to any one of claims 1 to 9.