Utilizing of b class carbon fiber in composite materials

Carbon fiber (CF) reinfoced polymer composites were fabricated by direct fiber feeding injection molding (DFFIM) process. Three polymer matrices were used including polyamide 66 (PA66), polypropylene (PP) and polycarbonate (PC). Two types of commercial treated CF with called a standard CF (CF-A) and a non-standard CF (CF-K) were applied in this research. Additionally, the CF-K was desizing to remove its surface treatment. The reinforcing fibers were fed into vented hole of the vented barrel injection molding of DFFIM process. The effect of fiber types and the desizing on tensile properties and morphology of the composites was investigated. The desizing of fiber promoted fiber dispersion, reduced fiber agglomeration and improved adhesion between fiber and the matrix. Hence, tensile modulus and tensile strength of the CF reinforced polymer composites. The DFFIM process would be an alternative fabrication for composites production in automotive industry. Introduction Fiber reinforced plastic (FRP) which made a contribution to the light weight process, was expected to replace the position of steel in automobile industry. Carbon fiber plays an important role as reinforcement in composite and achieved excellent properties [1-3]. Carbon fiber composites have very high mechanical properties and light weight, so that various application fields have been spread out to aerospace and aircraft industries. Not only contineous fiber reinforced composites but also short fiber composite fabricated by injection molding are important material system in automobile industry. However carbon fiber is expensive in short fiber composites. Research and developmet are needed to fully usage of carbon fiber performance; that means optimiation of fiber surface treatment, effective fiber length in products and so on. However, the high price obstructed the widely application of carbon fiber. On the other hand, the sub-quality products or the non-standard that called B-class carbon fiber were produced inevitably during the producing process or when the product type changes. At present, the electroconductibility of carbon fiber has been put into practical application as the raw material for IC tray to eliminate the effect of static electricity phenomenon. By this way, the B-class carbon fiber can be used widely as raw material of FRP, achieving a low cost as reinforcement. Regarding as far as the FRP products, fiber length, distribution, orientation and the interface between fiber and resin are the effecting aspects of the mechanical properties. By considering these four aspects during the injection molding process, the product made from B-class carbon fiber can be expected to achieve the comparable mechanical properties as A-class product or the standard fiber product. Normally in order to binding or treating carbon filaments, sizing agent is used, however the sizing agent prevent dispersion of the filaments in injection molding products. Poor dispersion state reduces strength of the composite because there is no resin adhered with bind ing