Current situation and development of prepreg standardization
I. Overview of prepreg
Prepreg is an important intermediate transition substrate for the preparation of composite materials, and its quality directly affects the performance of composite materials. With the development of composite technology, there are two types of thermosetting and thermoplastic prepregs. The quality of various prepregs seriously affects the process realization of composite materials and the properties of final products.CFRTP
Prepreg can be divided into unidirectional prepreg and fabric prepreg according to the physical shape of reinforcement. According to the width, there are wide and narrow bands. According to the type of reinforcement, there are carbon fiber reinforced prepreg, glass fiber reinforced prepreg and aramid fiber reinforced prepreg, etc. According to the curing temperature can be divided into low temperature (80℃), medium temperature (120℃), high temperature (180℃) curing prepreg; According to the different matrix resins used, the prepreg is mainly divided into thermosetting prepreg and thermoplastic prepreg two categories, in which the thermosetting matrix resin mainly uses epoxy resin, others include phenolic, unsaturated polyester, vinyl ester and so on. The reinforced fibers used are carbon fiber, glass fiber, aramid fiber, ultra high molecular weight polyethylene fiber, PBO fiber and so on.
Second, standardization status
Prepreg is an important intermediate material of composite materials and its properties will be extended to the composite materials. Therefore, the quality control of prepreg is very important. The properties of prepreg mainly include physical properties and chemical properties Physical properties include resin content, carbon fiber mass per unit area, volatile content, resin fluidity, gel time and viscosity and other chemical properties are mainly the standard infrared spectrum of the prepreg resin matrix.
According to incomplete statistics, China's prepreg standardization work has involved the development of national standards, national military standards, industry standards and local standards at multiple levels, and focused on the layout of the standard of prepreg experimental methods, and the overall importance of the aviation industry and building materials industry is higher.
3. Categories of prepregs with development potential
1, carbon fiber reinforced epoxy prepreg
Epoxy resin is the most used resin matrix for carbon fiber prepreg, and it is still the most important type of prepreg. Its excellent mechanical properties determine the good weather resistance, high toughness and processability of carbon fiber reinforced epoxy prepreg. It can be cured at medium temperature 120℃ and high temperature 180℃ respectively, and is widely used in aerospace, sports and leisure, ocean engineering, automotive lightweight and other fields.
2, high silica glass fiber cloth reinforced phenolic prepreg
The high silica glass fiber/phenolic material has the advantages of low cost, simple molding process, high strength and stiffness, good thermal protection performance, etc., and is widely used in the outer thermal protection layer of aerospace vehicles and engine nozzles. In a high temperature environment, a loose carbon layer structure is formed. With the further increase of temperature, the high silica fiber melts and produces a liquid layer with high viscosity, which is attached to the surface of the carbon layer structure and can play the role of heat shielding and radiation heat dissipation.
3, thermoplastic resin reinforced glass fiber prepreg belt
Thermoplastic prepreg belt has excellent mechanical properties, chemical corrosion resistance and heat resistance, easy to form and process and environmental protection. Continuous glass fiber /PPS thermoplastic prepreg tape is the ideal material for the manufacture of battery pack cover, which can withstand the burning of 1000℃ for more than 30 minutes, meeting the requirements of the battery cover for fire-resistant materials. In addition, compared with the complex casting, welding and other processes of metal battery boxes, the thermoplastic prepreg belt production process of battery boxes is simple, effectively reducing the production cost of battery boxes.
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