【Deep Coating Society Industry Analysis】Development status and prospect of polymer composite materials in China Composite materials gather | composite materials

Abstract: Because of its excellent comprehensive properties, high-performance polymer composites have become indispensable strategic key materials for national defense and national economic construction, and have been applied in aviation, aerospace, wind power generation, rail transit, automobile and other fields, with broad
development prospects 。 This paper analyzes the macroscopic needs of China's development of high-performance polymer composites, reviews the development status and characteristics of fiber reinforcements such as carbon fiber, aramid and high-performance glass fiber in high-performance polymer composites, as well as polymer resin matrices such as epoxy resin, phenolic resin and special resin for composite materials, and judges the problems in the development of high-performance polymer composites and the goals and tasks
of future development 。 It is found that the field of carbon fiber has initially formed an industrialization system from key technology research and development to engineering production, and the material has developed in both directions with high performance and low cost.
The initial success of para-aramid industrialization; Glass fiber maintains a low expansion rate; The high-performance polymer composite resin matrix industry is facing a severe development situation
.
Based on the development needs, development suggestions are put forward from the aspects of focusing on independent innovation, adhering to demand traction, attaching importance to industrial chain construction, strengthening talent training and supporting industrial innovation construction, in order to provide reference for the development of high-performance polymer composite materials in China
.

Composite materials gather to promote the digitalization, online and intelligence of the composite industry, and jointly build a composite ecosystem

I.
Preface

High-performance polymer composite materials refer to a class of materials represented by fiber-reinforced epoxy resins such as carbon fiber, aramid, glass fiber, and high-performance resins such as bismaleimide resins, which have excellent comprehensive performance and are indispensable strategic key materials
for national defense and national economic construction.
As the main material basis of high-end equipment, high-performance polymer composite materials play an irreplaceable role in the lightweight structure and ablative heat-proof parts of aerospace, aviation and other weapons and equipment, such as being used in
a new generation of weapons and equipment and major scientific and technological projects such as hypersonic vehicles, near space vehicles and deep space exploration vehicles.
At the same time, high-performance polymer composite materials are also widely used
in various major fields of the national economy represented by high-end industrial manufacturing, rail transit, clean energy, etc.

At present, a relatively mature industry has been formed in the field of high-performance polymer composite materials in the world and continues to develop
steadily.
In terms of reinforcement materials, carbon fiber, as the most important reinforcement for advanced composite materials, has become a research hotspot
for specialized or high-performance technologies for application needs and large-scale industrial-grade low-cost technologies.
In terms of para-aramid, the construction of the industrial chain has received more and more attention, the trend of technology integration has become more and more obvious, and emerging application fields have continued to emerge
.
The glass fiber industry has formed a complete industrial chain
from fibers, products to composite materials.
The development of resin matrix has entered an orderly and stable period
.
In composite material manufacturing technology, automated manufacturing technology is becoming more and more common, aviation and aerospace composite material technology has entered a mature period, the application of wind power and automotive fields has injected new vitality into the carbon fiber composite material industry, and the application of thermoplastic composite materials in rail transit and automobile industry has broad
prospects.

In recent years, with the further growth of demand for high-performance polymer composite materials in aviation, aerospace, wind power generation, rail transit, automobiles, high-pressure vessels and other industries, China's high-performance polymer composite materials industry has begun to take shape, and the application field and production capacity have continued to expand, gradually developing
in the direction of low cost and high performance.
Compared with foreign advanced levels, there is still a big gap
in the development of China's high-performance polymer composite material industry.
To this end, on the basis of sorting out the industrial development status and situation characteristics of various fiber reinforcements and resin matrices in China's high-performance polymer composites, this paper judges the manufacturing and application level of composite materials in China, analyzes the problems existing at this stage and the reasons for the gap with the international advanced level, and finally puts forward the future development direction and countermeasures of
China's high-performance polymer composites.

Second, China's high-performance polymer composite material macro demand analysis

High-performance polymer composites are indispensable strategic key basic materials for national defense and national economic construction, and are also the material basis
for the development of many key areas in "Made in China 2025".
With the transformation of China's national strategy and the proposal of new ideas for national economic development, the development and application of high-performance polymer composite materials have put forward urgent needs
.

1.
High-performance polymer composites are the key basic materials to achieve the support and support needs in the field of national security

With the implementation of China's national innovation-driven development strategy, the strategy of strengthening the country with space power, aviation power and ocean power as the main way has become the foundation
of the country.
The research and development of strategic missiles, new armor and ships, large aircraft, new generation fighters and satellites has a strong demand for high-performance, multi-functional, structure-function integration of high-performance advanced composite materials, and key composite materials and structural components have become bottlenecks restricting the completion of major national safety engineering tasks
.
For example, strategic and tactical missiles, hot end parts of aircraft engines, hypersonic vehicles, etc.
have an urgent need for carbon fiber composites above T800; The implementation of domestic large aircraft, advanced satellites and lunar exploration projects requires high-strength medium-mold, ultra-high-strength high-mode carbon fiber and its composite materials to guarantee
.

2.
High-performance polymer composites are key materials leading technological upgrading

In many key fields such as aviation and aerospace equipment, marine engineering equipment and high-tech ships, advanced rail transit equipment, energy-saving and new energy vehicles, new material industry, power equipment, new generation information technology industry, high-end CNC machine tools and robots, and high-performance medical equipment, high-performance polymer composite materials are key basic materials or upgrading materials
leading the technological revolution 。 For example, the use of carbon fiber composite materials on the beam cap and main beam of wind turbine blades with a length of more than 40m can reduce the blade weight by 38% and the cost by 14% on the one hand; On the other hand, to improve the fatigue resistance of the blades and increase the power output, it is easier to produce large-diameter and adaptive wind turbine blades
made of carbon fiber.

3.
High-performance polymer composites are an urgent need to achieve the green development of China's economy

In the case of limited energy innovation, energy conservation and emission reduction are important research topics in the automotive industry, and lightweight is one of
the keys to solving the problem.
Advanced polymer composites have outstanding advantages such as high specific modulus and specific strength, great weight reduction potential and good safety, and are the best choice for
automotive lightweight.
With the continuous advancement of composite technology, carbon fiber composite materials have been applied to automobile bodies, rear wings, chassis, hoods, interiors, etc
.
In the future, the growth rate of carbon fiber demand in the automotive industry will remain at about 7% for a certain period of time
.

Third, the development status of high-performance polymer composite materials in China

At present, although the development of high-performance polymer composite materials in China has made substantial progress, the industrialization process of high-performance fiber reinforcements, resin matrices and composite materials preparation is relatively slow, and there is still a certain gap
in some fields compared with the world's material powers.
The development of high-performance polymer composite materials in China is as follows
.

(1) The development of high-performance fibers has its own characteristics

1.
The field of carbon fiber has initially formed a research and development and production platform, and has developed rapidly in the direction of high performance and low cost

Carbon fiber is a class of inorganic fibrous materials with carbon content of more than 90%, of which polyacrylonitrile (PAN) fiber is the most important polyacrylonitrile-based carbon fiber prepared as a precursor, and its preparation process mainly includes the preparation of acrylonitrile (AN) polymer solution, the preparation of PAN precursors, PAN fiber preoxidation, PAN preoxide fiber carbonization and surface treatment for resin composite, if the preparation of high modulus carbon fiber also needs to go through the high-temperature graphitization process
.
The production and preparation process of PAN-based carbon fiber is shown in
Figure 1.
With the support of the National Science and Technology and Industrialization Demonstration Program, after more than 10 years of collaborative research, China's high-performance carbon fiber preparation and application technology has made a major breakthrough.

(1) Initially establish high-performance carbon fiber technology and product system, and the technical level has been continuously improved

At present, China's domestic carbon fiber has initially realized the industrialized large-scale production
of T300 grade and T700 grade carbon fiber.
Specifically, the performance of T300-grade carbon fiber has basically reached the international level, and its application in the field of national defense is gradually maturing, and its application in the civilian field still needs to be developed; T700 grade and T800 grade high-performance carbon fiber break through the dry spray wet spinning process and realize industrial production; Innovative development of wet spinning T700 grade carbon fiber preparation process, related products have been applied to the aviation field; Under laboratory conditions, T1100 grade high-performance carbon fiber has broken through key preparation technologies
.
In the field of high-modulus and high-strength high-mode carbon fiber, M40-grade high-modulus carbon fiber has achieved small batch production, with a production capacity of about 300kg/a, and has been applied to multiple satellite models; M40J grade high-strength and high-mode carbon fiber has been developed and is undergoing application assessment; M55J grade high-strength and high-mold carbon fiber is still in the engineering development stage, and higher performance carbon fiber varieties are still in the key technology research and development stage
.

(2) A number of carbon fiber production enterprises and R&D platforms have been established, and the domestic carbon fiber industry pattern has basically formed

In terms of carbon fiber production enterprises, there are more than 20 carbon fiber enterprises in China, mainly distributed in Shandong, Jiangsu, Hebei and Jilin, and the industrial pattern of domestic carbon fiber has basically formed
。 Six enterprises, represented by Weihai Development Fiber Co.
, Ltd.
, Jiangsu Hengshen Co.
, Ltd.
, Zhongfu Shenying Carbon Fiber Co.
, Ltd.
, Zhonganxin Technology Co.
, Ltd.
, Jilin Jinggong Carbon Fiber Co.
, Ltd.
, and Sinopec Shanghai Petrochemical Co.
, Ltd.
, have built more than 10 single-line production lines with a capacity of 1,000 tons, and another 18 enterprises have built production lines with a capacity of tens to hundreds of tons; At the same time, the high-strength large tow carbon fiber precursor technology based on the acrylic industry has made a breakthrough, and Jilin Carbon Valley Carbon Fiber Co.
, Ltd.
has built a precursor production line with a production capacity
of 1.
5×104t/a.
In 2019, the theoretical production capacity of domestic carbon fiber reached 2.
6×104t/a, the effective production capacity was about 1.
5×104t/a, and the T300/T700 grade carbon fiber produced basically met the application needs
of the defense field.
Although the production capacity of the carbon fiber industry is constantly growing, there are problems such as
large production capacity, small output and insufficient operating rate.

In terms of platform construction, China has built a lot of carbon fiber science and technology research to support the localization of carbon fiber industry, namely 1 national carbon fiber engineering technology research center, 2 national engineering laboratories of carbon fiber preparation technology, 2 national engineering laboratories of carbon fiber composite materials, and several national key laboratories
.

2.
The industrialization of para-aramid is successful, but there is still a gap compared with the international advanced level

para-aramid is an important member of the para-aromatic polyamide fiber family, which is a polymer terephthaloyl p-phenylenediamine prepared by polycondensation of terephthaloyl chloride and p-phenylenediamine, and then prepared by solution spinning
.
The total international para-aramid production capacity is about 7.
6×104t/a, and the operating rate is about 70%~80%.

At present, 8 enterprises in China have built para-aramid fiber production equipment, with a production capacity of more than 7×103t/a, and the specific capacity distribution is shown
in Figure 2.
However, the actual annual output of the country is about 1.
8×103t, and the industry operating rate is less than 30%.

Generally speaking, the gap between the industrialization level of para-aramid in China and the advanced level of foreign countries is large, and a strong competition pattern
has not yet been formed in terms of industrial scale, product quality and application.

In terms of platform construction, China has established a number of national and local R&D and technology platforms
for aramid fibers.
For example, Donghua University is the State Key Laboratory of Fiber Material Modification, South China University of Technology is the State Key Laboratory of Pulp and Paper Engineering, Yantai Taihe New Materials Co.
, Ltd.
is the National Aramid Engineering Center, and Zhonglan Chenguang Chemical Research Institute Co.
, Ltd
.
is the support for the research and development of multi-variety, small-batch military materials such as fibers.

3.
Glass fiber production capacity ranks first in the world, maintaining low-speed expansion

Glass fiber is an excellent functional material and structural material
.
In 2016, the national glass fiber production capacity was about 3.
8×106t/a, accounting for 60%
of the global total production capacity.
From 2017 to 2019, the average annual compound growth rate of China's glass fiber production capacity was 6.
65%, which was much higher than the average annual compound growth rate of 1.
70%
of global production capacity.
The annual output of glass fiber in China increased from 9.
5×105t in 2005 to 3.
62×106t in 2016, and the average annual compound growth rate of output reached 12%.

Since the 13th Five-Year Plan, glass fiber production capacity has maintained a low speed of expansion, and the new production capacity is mainly concentrated in a few enterprises, such as China Jushi Co.
, Ltd.
has completed the transformation of 5 production lines, Taishan Glass Fiber Co.
, Ltd.
has built a new pool kiln production line, and Chongqing International Composite Materials Co.
, Ltd.
has put into production a cold repair line
.

(2) The development situation of high-performance epoxy resin and phenolic resin for composite materials is grim

1.
Epoxy resin

Epoxy resin is a thermosetting resin formed by polycondensation of epichlorohydrin and bisphenol A, which is widely used as a matrix resin for composite materials, especially in aviation composite materials
.
In 2016, the world's total epoxy resin production capacity was about 4.
62×106t/a
.
At present, the epoxy resin production capacity of three companies, Dow Chemical Company, Nanya Plastic Industry Co.
, Ltd.
and Momentive Specialty Chemicals Co.
, Ltd.
, ranks among the top three in the world, accounting for 37%
of the total epoxy resin production capacity in the world.
The production capacity of China's epoxy resin industry in 2017 was 2.
3×106t/a, accounting for 50% of the world's total production capacity, and the output in 2017 was 1.
2×106t
.
9% of the epoxy resin produced in China is used in the field of composite materials, and the rest is used in electronic appliances, coatings, adhesives and other fields
.

O-cresol epoxy resin is an epoxy resin obtained by replacing bisphenol A with o-cresol resin, which has a higher epoxy value than bisphenol A epoxy resin, and can provide 2.
5 times the cross-linking point when cured, so that the composite material has higher thermal stability, mechanical strength, electrical insulation and chemical resistance
.
At present, the world o-cresol epoxy resin market is basically monopolized by enterprises in Japan, the United States, Switzerland and other countries, and China cannot produce high-quality, high-purity o-cresolaldehyde epoxy resin
on a large scale.

Typically, epoxy resins are cured to form a mesh of three-dimensional polymers, which envelop the composite bone in
a mesh.
According to different curing temperatures, it can be divided into room temperature curing (20~30 °C), medium temperature curing (50~130 °C), high temperature curing (above 130 °C), etc
.
Compared with high temperature curing, medium temperature curing has the advantages of low curing temperature, less strict requirements for molds, low internal stress and dimensional stability, and has broad development space
.
In order to avoid problems such as poor toughness and strong brittleness of the cured epoxy resin, it needs to be toughened and modified, including toughening of rubber elastomers, toughening of high-performance thermoplastic polymers, toughening of thermogenic liquid crystal polymers, etc
.
In addition, it is also necessary to modify the flame retardant of epoxy resin, and halogen-free flame retardants have been widely studied and applied
in recent years.
The functional monomer with a certain amount of N, Si or P elements in the molecular structure is used as a reactive monomer or curing agent for flame retardant epoxy resin, so that the resin composite material has good flame retardancy
.
At present, domestic flame retardant manufacturers such as Zhejiang Wansheng Co.
, Ltd.
, Jiangsu Yake Technology Co.
, Ltd.
, etc.
have begun to produce organophosphorus-based halogen-free flame retardants, but the overall level and effect are still far from
developed countries.

2.
Phenolic resin

Phenolic resin, as a matrix resin widely used in composite materials, is a thermosetting resin formed by polycondensation of phenolic compounds (such as phenol) and aldehyde compounds (such as formaldehyde), of which the most typical and important phenolic resin is a polymer
made of polycondensation of phenol and formaldehyde.
In 2016, there were about 200 phenolic resin manufacturers in China, with a production capacity of about 1.
3×106t/a and an output of about 1.
02×106t, ranking first in
the world.
However, for some high-performance phenolic resins and their composite technologies, casting technologies, etc.
, China has not yet mastered the core key technologies, and it is urgent to improve the phenolic resin modification and casting level of
domestic enterprises.

Phenolic resin has high brittleness, low elongation, and its structure of phenolic hydroxyl and methylene is easy to oxidize
.
In order to meet the requirements of phenolic resin performance in aviation, aerospace and other high-end fields, toughening modification and heat resistance modification are required
.
Among the existing modified phenolic resins, boron phenolic resins introduce B elements into the molecular structure of phenolic resins, so that phenolic resins show the characteristics of high oxygen index, low toxicity, low smoke, etc.
, and are one of
the important materials urgently needed in rockets, aerospace, missiles, nuclear power plants and automobile brake pads.

3.
Special resin matrix

In terms of special resin matrix, there are mainly bismaleimide resin, cyanate resin, benzoxazine resin,
etc.
These special resins have good heat resistance, flame retardancy, radiation resistance, wave transmission, electrical insulation and mechanical properties, and are considered to be a class of thermosetting polymer matrix resins with broad development prospects, which are expected to become the successor of epoxy resins and are widely used
in the field of aviation and aerospace.
In the fourth generation of the American fighter F-22, the amount of composite material accounted for 24% of its total structural mass, of which 70% was a two-horse resin matrix composite
.

In the past 30 years, the United States, Japan, the United Kingdom, Germany and other countries have successively carried out a lot of modification research on special resin matrices such as bismaleimide resin to prepare matrix resin materials
with better performance.
These special resins are developed and produced in China, and compared with the international advanced level, there is a big gap
in mass production scale and product stability.
As a high-performance material, special resin matrix composites need to solve two major technical problems in practical application: (1) improve the processing performance of the resin through copolymerization, blending or other methods, and solve the problems of brittleness and easy fracture caused by solid-phase high-temperature curing molding; (2) While ensuring that the material has sufficiently high heat resistance, mechanical properties and mechanical strength, it also improves toughness and prepares composite materials that integrate strength, toughness, heat resistance, processability and other excellent properties to meet the requirements
of aviation, aerospace and other military fields.

(III) China's composite material manufacturing and application level has developed significantly

1.
Composite technology has entered a mature period and began to be applied on a large scale

(1) In the aviation field, the application level of composite materials has been improved, and the proportion of composite materials is getting higher and higher, such as the composite material of China's fourth-generation fighter aircraft accounts for 25%, the composite material of large transport aircraft accounts for 15%, and the composite material of a certain helicopter accounts for 34%.

In addition, China's large passenger aircraft in the research and development stage plan to use carbon fiber composite materials in tail, wing and other structures, and the amount of composite materials will account for 15%~25%
of its structural weight.
(2) In the aerospace field, with the continuous improvement of resin matrix performance and the gradual application of advanced process technology, the application trend of composite materials in China's aerospace structure has developed
from small-size sub-bearing structure to large-size main load-bearing structure.
(3) In the weapons industry, glass fiber, carbon fiber reinforced composite materials, etc.
are mainly used, and their application scope has developed from non-bearing and sub-bearing structural parts to main bearing structural parts, such as high internal pressure rocket engine shell resistant to high overload, large-caliber armor-piercing bullet stock, etc
.
According to incomplete statistics, the annual consumption of glass fiber in the weapons industry has reached thousands of tons, and the annual consumption of carbon fiber, aramid fiber and polyethylene fiber has reached more than
50t, 70t and 10t respectively.
(4) In the civil field, the application of composite materials in wind power generation and automobiles has injected new vitality into the carbon fiber composite industry, and thermoplastic composite materials have broad
application prospects in the field of rail transit and automobile industry.

2.
Composite material automation manufacturing technology is becoming more and more mature

With the wide application of high-performance composite materials, the composite material manufacturing process is developing rapidly in the direction of diversification and automation, and the composite material molding process has developed from 2~3 kinds (hand lay-up and manual laying) to nearly 10 kinds (automatic laying), and the proportion of automatic manufacturing of composite components will reach 50% in 2016 and will reach more than
65% by the end of 2020 。 During the Twelfth Five-Year Plan period, China's composite material automation manufacturing technology has been well developed, automatic tape laying, automatic wire laying and prepreg automatic pultrusion and other advanced and efficient process technologies are gradually being put into application, the development of hot melt prepreg production and autoclave composite molding process technology, fiber/cloth tape winding molding technology, resin transfer molding molding process (RTM) molding technology and composite structure integral molding technology, composite material manufacturing technology system has taken shape, can be used for the development and small batch production of carbon fiber, Glass fiber and aramid reinforced high-performance phenolic resin, epoxy resin, bismaleimide resin and polyimide and other composite materials, mainly used in auto parts, rail transit, communication power, building materials, electricity/electrical appliances, municipal infrastructure, new energy development and other fields, basically meet the needs
of aviation, aerospace, weapons, energy and transportation fields.

3.
The structural and functional integration composite material technology is developing rapidly in the direction of high-end and practicality, which supports the development and production of high-end equipment

China's structural and functional integration composite material technology has developed significantly, and structural absorbing and wave-transmitting composite materials have been widely used
in new aircraft, missiles, ships, ground vehicles and other fields.
The first generation of bulletproof/structural composites - high-strength glass fiber reinforced resin matrix composites, the performance has reached the US MIL-46197A structural armor composite standard, has been used in a variety of armored equipment hatches
.
The second-generation anti-bullet/structural composite materials have the characteristics of multi-functional integration such as anti-bullet, load-bearing and stealth, and have outstanding absorption effect in a wide radar band while maintaining high rigidity and elastic performance, and have been used in the roof cover and exposed parts
of large power compartments of tanks.
Under the impetus of the development plans of manned spaceflight and star exploration, China's resin-based heat-proof composite materials have developed honeycomb reinforced low-density resin-based heat-insulating composites and successfully applied
them on the manned return capsule.

High-performance carbon fiber composite materials are the core of the composite industry, in 2016, the annual amount of carbon fiber composite materials in the world is about 1.
1×105t, the total market value is about 20 billion US dollars, and the market development prospects are broad
.
After more than 30 years of development, China's composite materials have established a number of composite component research and development platforms and manufacturing bases to promote the improvement of
composite technology and industrial level.

Fourth, the development of high-performance polymer composite materials facing the problems

At present, China's high-performance polymer composite materials represented by carbon fiber reinforced composite materials are still in the development stage, and there is still a big gap
compared with foreign advanced levels.
China's related product research and development and industrial development direction is mostly benchmarked against existing foreign products, mainly tracking imitation, product import dependence is high, industrialization process is slow, and some fields seriously lag behind the development speed
of world material powers.

(1) There are few high-end carbon fiber products, low-end products are expensive, and the development of para-aramid is difficult

The development of various varieties of high-performance fibers in China is uneven
.
For high-performance inorganic fibers, glass fiber has entered the mature stage of industrialization, with good product quality and high market share; Carbon fiber is in the early stage of industrialization, the production capacity is constantly increasing, but the output and market share are low, and the stability of product quality needs to be improved; Aramid fiber is in the early stage of industrialization and has a certain production capacity, but the output is low, and the product quality stability and market share need to be further improved
.

The production cost of domestic carbon fiber remains high, and there is a generation gap between high-performance carbon fiber used in aviation, aerospace and other fields, and the ability of independent innovation needs to be strengthened
.
At the same time, China's carbon fiber application market cultivation is slow, wind power, automotive and other industries have not yet been applied on a large scale, and the pulling force of industrial demand is weak
.
The products of existing carbon fiber enterprises are mostly concentrated in the production of T300-grade carbon fiber, there is a certain low-level disorderly expansion, coupled with foreign related enterprises to China's low-grade carbon fiber price suppression, is not conducive to the growth of carbon fiber industry, difficult to form a competitive and sustainable and healthy development of the industry
.

In terms of para-aramid, foreign companies continue to accurately suppress China's aramid products through price means, resulting in the use of 118 China's high-performance polymer composite materials development status and the enthusiasm of domestic aramid products are not high
.
At the same time, domestic aramid manufacturers are also facing the challenge
of strengthening export control of aramid monomer (terephthaloyl chloride) abroad.
In short, at present, the growth and development of China's aramid industry is full
of difficulties.

(2) There is a gap between the research and development and application level of resin-based materials

The resin matrix is the weakest and first component of fiber-reinforced composites and plays a key role
in the overall performance of the composite.
The problems and gaps in resin matrix in China are mainly manifested as follows: (1) the research and development strength is weak, the research body is mainly universities and scientific research institutes, and the application research of composite materials is relatively disconnected from enterprises; (2) Low large-scale production capacity of high-quality, high-purity epoxy resin, phenolic resin and modified high-end products; (3) In view of the requirements of advanced composite materials in high-end fields, the design ability of resin compounding system needs to be strengthened; (4) The industrialization ability of high-performance resin matrix is insufficient, and there is a lack of products
that meet the performance of low frequency band, omnidirectional stealth, wave transmission, low density, anti-heat insulation, and bulletproof.
In addition, it is necessary to increase the application of new metamaterials, frequency selection, graphene and other new technologies and materials in the field of structural absorption and wave transmission
.

(3) The design, manufacture and application level of resin matrix composites are low

(1) The design of structural parts of composite materials in China is mainly based on tracking alternative applications, and the ability of independent design and application is weak
.
At present, according to foreign practical application statistics, the weight reduction efficiency of the main load-bearing structure using T300-grade carbon fiber composite materials can reach 25%, while the weight reduction efficiency in China is relatively low, most of which are less than 20%.

(2) The application proportion of domestic composite material automation molding process is low, less than 20% overall, mainly limited to high-end fields such as aviation and aerospace, and civil composite materials are still dominated by traditional hand lay-up or manual paving molding, which has a significant gap with
foreign automated manufacturing levels.
The backward process makes the composite materials have discrete, low yield and high cost, which has become a prominent problem
restricting the development of high-performance composite materials.

(3) The technical level of key equipment for composite material manufacturing is weak, mainly imported and supplemented by imitation, and some equipment such as hot melt prepreg machine, winding machine, autoclave, hot press machine design and manufacturing, as well as the development of composite material automatic laying equipment and prepreg automatic pultrusion equipment, although a certain breakthrough has been made, but the dependence on imported equipment in scientific research and production is still high
.

(4) There is a clear gap
between the application level of high-performance resin matrix composites and the advanced level of developed countries.
The composite material of ARJ21 regional passenger aircraft developed in China accounts for about 2%, the composite material of C919 medium passenger aircraft under development accounts for about 10%, and the latest foreign development of Boeing 787, Airbus A350 and other large passenger aircraft composite materials account for more than
50%.
Eurocopter's NH90 helicopter composite material reached 95%, while the composite material of the new domestic helicopter Z10 accounted for only 34%.

The large-scale application of high-performance resin matrix composites in large passenger aircraft, wind power and automobiles has not yet been broken, and the composite industry has not yet formed a scale
.

(5) The foundation of structural and functional composite materials is weak, and the comprehensive design ability
of technological development is lacking.
The research of raw materials such as reinforcing materials, resin matrix, and functional fillers is scattered, with low level and serious homogenization competition, and the performance cannot meet the existing needs
.
New metamaterials, frequency selection, graphene and other new technologies and materials have made certain progress in the application of structural absorption and wave transmission, but they are still in the stage of theoretical design and experimental verification, and there is still a gap
from the requirements of practical engineering applications 。 Although China has made obvious progress in the research of structural/absorbing composites, structural/ballistic composites, and structural/heat-resistant composites, the development of structural functional composites still has problems such as lack of top-level design, insufficient resource integration ability, lack of important fields, insufficient interdisciplinary comprehensive design ability and insufficient technology sharing, and low-level repetition, and has not yet formed a generalized, serialized and standardized material system, and lacks high-performance products
to support future technological development.

5.
The development goals and development suggestions of high-performance polymer composite materials in China

(1) Development goals

1.
Towards the development goals of 2025

The development goals for 2025 are: to complete the serialization of domestic carbon fiber varieties, process diversification, production capacity scale, high-strength, high-strength medium mold and high-mode high-strength carbon fiber main products to meet application needs, with industrial competitiveness; Breakthrough in large-scale integrated para-aramid production and preparation technology, built a 10,000-ton production line; Establish a large-scale preparation and application platform for the second generation of advanced composite materials based on high-strength medium-mold carbon fiber, realize the application in major projects such as large aircraft and manned spaceflight, and be comprehensively replaced and applied in weapons and equipment, reaching the world's advanced level
.

The key development directions include: (1) Strengthen the research and development of domestic carbon fiber high-performance and low-cost preparation technology, break through the localization technology of T1100 grade carbon fiber, carry out M55J grade high-mode and high-strength carbon fiber stability engineering technology research and M65J grade carbon fiber preparation key technology research, and realize the application
of national defense models 。 Breakthrough in the domestic carbon fiber preparation technology with high strength, high mold, high toughness and high elongation, compression and tensile properties balanced development characteristics; Carry out research on low-cost industrial preparation technology of T300, T700 and T800 grade carbon fiber with a scale of 1,000 tons and above, and carry out research on the integration of high-speed dry spray wet spinning process system technology; Breakthrough in the key technology
of mass production of large tow carbon fiber above 48K.
(2) Break through the large-scale integrated para-aramid production and preparation technology and build a 10,000-ton production line
.
(3) Carry out carbon fiber composite material design and application technology research in aviation and aerospace fields, including resin design improvement and large-scale synthesis technology for high-toughness prepreg matching domestic T800 grade carbon fiber, RTM resin formula design and large-scale synthesis technology, domestic high-strength medium-mold carbon fiber prepreg quality and performance consistency control technology, RTM composite toughening technology, composite material fast beat manufacturing technology research, domestic high-strength medium-mold carbon fiber composite airworthiness verification technology, etc
。 (4) Carry out research on high-strength, high-mold, high-toughness, tensile-pressure balanced carbon fiber reinforced resin matrix composite materials, and develop the third-generation advanced composite materials
with the goal of comprehensively replacing high-performance aluminum alloys.
(5) Realize the application
of domestic low-cost high-performance polymer composites in construction, wind turbine blades, transmission lines, automobiles and rail transit and other fields.

2.
Towards the development goals of 2035

The development goal for 2035 is to establish high-performance reinforced fiber technology and product series that meet China's application needs through independent innovation, and form a continuous independent support capability
for domestic high-performance fibers and composite materials for national defense.
We have developed new high-performance fiber composite materials necessary for national advantageous industries, strategic industries and new weapons and equipment, and improved product performance and market competitiveness
through large-scale verification in the use of environment.
Realize the industrialization and promotion and application of domestic high-performance polymer composite materials, so that China's composite material technology can reach the world's synchronous development level and gradually achieve a comprehensive surpassing and leading international development level
.

The key development directions include: (1) Realize the engineering preparation of high-performance carbon fiber at M55J, M65J, T1100 and other levels to meet the needs
of national defense industry and national economic development.
(2) According to the requirements of material properties in the actual service environment, realize the structural design of high-performance new resin matrix and ultra-micro interface control of polymer composite materials, and realize the development of new technologies such as new methods for rapid prototyping of
composite materials and integrated molding of super-large composite materials.
(3) Establish a domestic polymer composite material industry technology innovation system to meet the needs of major fields of
national defense and national economy.

(2) Countermeasure suggestions

1.
Pay attention to independent innovation and promote the sustainable development of the industry

The development of high-performance polymer composite materials should adhere to the application of major fields as the guide, scientific understanding as the basis, key technology breakthroughs as the center, industrial innovation as the goal, not only aiming at the urgent needs of major national projects, but also taking into account the development of cutting-edge science and technology, eliminating the phenomenon of disconnection between preparation and application, rapidly improving the maturity of industrial technology, and establishing a strict scientific and reasonable operation mechanism
.

2.
Adhere to the demand for high-end equipment as the traction to make technological breakthroughs, promote industrial development through the scale of civilian demand, and achieve a virtuous circle

Driven by the development trend of high-performance polymer composite materials with high performance and low cost, guided by the demand for high-end products in the field of national security such as aviation and aerospace, we continue to make technological breakthroughs and provide key strategic basic material support, and at the same time expand their application in the civilian fields represented by automobiles, wind power generation, pressure vessels, etc.
, improve the hematopoietic function of the enterprise, realize the healthy and sustainable development of the domestic high-performance polymer composite material industry, and meet the needs of national security, national defense modernization.
The needs of
the national economy and the country's medium- and long-term major projects.

3.
Attach importance to the construction of high-performance polymer composite material industry chain, and establish an efficient and low-cost application technology system for carbon fiber composite materials

Strengthen investment and guidance, from high-performance fiber reinforcement – composite materials – market applications to carry out system layout and technical research, and lay a solid foundation
for development.
Focus on cultivating hard power of technology and equipment, and build a complete industrial technology chain integrating composite design, manufacturing, and application
.
Promote the development of high-performance polymer composites in key civil industries such as energy, transportation, and construction engineering, and form a complete industrial chain
of R&D and production of high-performance fiber reinforcements, R&D, production of high-performance resins, and preparation and application of composite materials.

4.
Strengthen talent training, respect intellectual property rights and standardization, and support the construction of industrial innovation centers

It is recommended to strengthen the integration of relevant interdisciplinary majors, expand the scale of talent training and strengthen the training of interdisciplinary compound talents; Establish high-level open research platforms such as enterprise technology centers and key laboratories in key enterprises, and effectively strengthen and improve the process technology level of enterprises; Attach importance to the establishment of testing standards, process standards and product quality standards; Respect intellectual property rights, establish a reasonable and orderly talent flow mechanism, and provide independent innovation source power
for the sustainable and healthy development of China's high-performance polymer composite technology industry.

Source: China Engineering Science, 2020 Vol.
22 Issue 5 Authors: Cao Weiyu, Yang Xueping, Zhang Ronsheng

Source: China Engineering Science

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