INFLUENCE OF MATRIX MOLECULAR-WEIGHT AND PROCESSING CONDITIONS ON THEINTERFACIAL ADHESION IN BISPHENOL-A POLYCARBONATE CARBON-FIBER COMPOSITES

The adhesion of bisphenol-A polycarbonate, an amorphous thermoplastic, to carbon fiber was studied by varying both the intrinsic and the ext rinsic properties such as the molecular weight, processing conditions, and test temperature. It was seen that processing methods and conditi ons had a significant effect on adhesion as measured by the interfacia l shear strength. Commercial grade Lexan 141 solvent deposited onto ca rbon fibers showed poor adhesion when processed below the glass transi tion temperature and reached a limiting value at a higher temperature. Melt consolidated pure polycarbonate specimens showed increases in ad hesion both with increasing processing temperature and with time, Pure polycarbonate having a molecular weight above the critical molecular weight exhibited a higher adhesion at different processing conditions, while for polycarbonate below the critical molecular weight adhesion was poor and unaffected by the processing temperature. Increases in te mperature lowered the adhesion as a result of the dependence of adhesi on on the matrix modulus, which decreases with increasing temperature.