Three forms of CFRTP as raw materials: pellets, composite yarns, prepregs

With the continuous upgrading of products, the demand for high-performance lightweight composite materials in downstream applications is also increasing. Carbon fiber reinforced thermoplastic composites with light weight, high temperature and wear resistance, not easy to be corroded, small creep, and strong comprehensive properties have also gained new development opportunities. However, due to the upstream preparation technology of carbon fiber and the expensive material cost, the application of carbon fiber reinforced thermoplastic composites (CFRTP) in China has not yet begun.

As far as the current situation is concerned, CFRTP mainly has three forms as raw materials: pellets, composite yarns, and prepregs, and the processes involved and application effects are different to some extent.

Form 1: Carbon fiber reinforced thermoplastic composite pellets

Carbon fiber reinforced thermoplastic composite pellets with chopped carbon fiber as reinforcement material and resin such as PA6/6, PPA, PEI, PPS, PEEK and PAEK as matrix can be used to produce parts with complex structure through injection molding process. Because this raw material can be produced at a faster rate and with higher consistency, this raw material is most widely used in the automotive market where application costs and consumption are high. However, various experiments have shown that the longer the single fiber in the same volume content of the composite material, the fewer the number of fibers, polyethylene wax emulsion uses, the less stress concentration caused by the fiber end, and the more difficult the material damage. And in a certain length range, the longer the fiber, the more energy it absorbs when it is pulled out, and the more significant the strength improvement is. Therefore, compared with continuous carbon fiber reinforced thermoplastic composites, carbon fiber reinforced thermoplastic composite pellets have obvious deficiencies in mechanical properties.

Form 2: Carbon fiber reinforced thermoplastic composite yarn

Carbon fiber reinforced thermoplastic composite yarns are generally used to make thermoplastic composite material profiles. Through the procedures of flattening, impregnating, exhausting, compacting, cooling, and cutting, the high pressure and high temperature of the molding die promote the molten thermoplastic resin and carbon fiber. Interpenetration between yarns. The process is often associated with a semi-continuous automated manufacturing CCM technology for the manufacture of virtually unlimited lengths of thermoplastic composite flat sheets or highly formed profiles. The advantages of this process are high productivity and consistent quality. and dimensional consistency. However, the application of such raw materials and processes is very limited. One is that it can only form products with simple cross-sections and less surface area, and cannot produce parts with various forms and complex structures like prepreg. Raw materials and processes cannot achieve multi-angle layup design, because the direction of reinforcing fibers is too single, and it is difficult to meet the product performance requirements that require high warp and weft strength.

Form 3: Continuous Carbon Fiber Reinforced Thermoplastic Composite Prepreg

As a material with extremely high unidirectional tensile strength and modulus, continuous carbon fiber reinforced thermoplastic unidirectional prepreg tape has comprehensive properties far exceeding that of carbon fiber reinforced thermoplastic composite pellets, and is far superior to carbon fiber in terms of plasticity and product complexity. Reinforced thermoplastic composite yarn. Zhishang New Material Technology is one of the earliest manufacturers in China that started to study the continuous carbon fiber reinforced thermoplastic melt impregnation process. This process puts forward high requirements for continuous carbon fiber spreading and impregnation with thermoplastic resin. The viscosity of thermoplastic resin is very high, so the yarn should be spread enough and thin enough, the amount of dip coating of the resin matrix should be uniform, and the carbon fiber must be fully infiltrated in the resin matrix to ensure good performance. After several years of continuous efforts, Zhishang New Materials has completed the mass production target of continuous carbon fiber reinforced PA/PPS/PEEK series of unidirectional prepreg tapes. The parts made with this prepreg tape have high tensile strength. Elongation and tensile strength at break, as well as good impact strength, have excellent performance in high temperature resistance, wear resistance, corrosion resistance and light weight.