Abstract
Application of the microbond method to thermoplastics was investigated. Adhesion (shear strength) between carbon fiber and various polypropylenes (PP) was evaluated by the microbond method. Optimum measurement conditions such as the conditioning time from droplet application to measurement and the embedded length of the fiber in the resin and the effect of viscosity (melt flow index) of the resin were studied. Shear strength was measured successfully for conditions of an embedded length from 100 to 250 μm and of a time of 3 or 4 days. In order to improve the adhesion, a maleic anhydride-grafted PP (MPP) was mixed with PP and carbon fiber was treated by various plasmas. Addition of MPP to PP increased the shear strength by 50% for untreated carbon fiber and by 70% for O2 plasma treated carbon fiber.
