Fiber Sizing Treatment And Properties Of Sizing Agent Treated Fiber Composites

Nowadays composites with high strength and environmentally friendly behaviorare becoming increasing important. Fiber reinforced composites attract much attentionbecause of their high strength, easy processing, corrosion resistance and so on. Thestrength of the composites is attributed to not only the material itself, but also theinterface bonding between materials. Thus, surface modification to improve interfacebonding has become a research hotspot. In this paper, carbon fiber reinforced PA6composites and corn fiber reinforced PLA composites were successfullymanufactured. Mechanical properties, heat deflection temperature (HDT), melt flowindex (MFI) and crystallinity of the composites were investigated by means ofuniversal tester, impact testing machine, DSC, SEM and TEM etc..Sizing agent was employed to treat carbon fibers before the preparation ofCF/PA6composites. The results showed that concentration of sizing agent had greatinfluence on the strength of the composites. Tensile and flexural strength of thecomposites increased initially up to the maximum at22wt%sizing agent. However,with increasing the concentration of sizing agent, the processability of compositesincreased all the time. At the same filler fraction, the tensile and flexural strength ofthe composites were significantly improved at the condition of adding a little couplingagent and decreased when added more coupling agent. KH560had great influence onthe tensile and flexural strength of the composites than other coupling agent. But nosignificant difference was found on flow properties of the composites treated withdifferent coupling agent. CF/PA6composites with different fiber content weremanufactured under the optimum process and the highest strength was obtained at20wt%fiber content. The thermal deformation temperature could be dramaticallyimproved with the addition of a small amount of carbon fibers. Flowability of thecomposites decreased with increasing the content of carbon fiber.Sizing agent treated corn fibers were added to the PLA to prepare CFA/PLAcomposites. Tensile and flexural strength, the glass transition temperature, thecrystallinity and melting point of composites treated with sizing agent are higher than those of the composites treated with alkali only or alkali/silane co-treated. However,no great difference was found on the heat distortion temperature of composites withdifferent treatment. Concentration of sizing agent is also responsible for themechanical properties of the composites. CFA/PLA composites with different fibercontent were manufactured under the optimum process and verified that fiber contenthas great influence on the mechanical properties of the composites. Moreover, tensile,flexural and impact strength of the composites were further improved when sizingagent was modified by nano-silica, and the highest strength level of the compositeswere achieved at the content of1wt%nano-silica.