Abstract
Tensile strength of injection-molded short glass fiber reinforced thermoplastics was remarkably decreased by the addition of a slight amount of titanium dioxide (TiO2) . Generally it is explained that the strength deterioration is due to much shortening of glass fiber length under processing, since the hardness of TiO2 is higher than that of glass fibers. In this study, the influence of the addition of TiO2 (0.2 wt%) to short glass fiber reinforced polyamide 6 on the strength of glass fibers in the composite was investigated. The tensile strength of the composite containing TiO2 was fairly lower than that of the composite without TiO2, even if the glass fiber lengths in the composite were unchanged. However, numerous flaws were observed on the surface of glass fibers in the composite containing TiO2. After tensile test of the composites, the pull-out lengths of glass fibers were measured and the variation of Weibull moduli was estimated by using the data based on the Weibull weakest-link theory. As a result, the value of scale parameter decreased markedly by the addition of TiO2. Namely, it was found that the main factor of the strength deterioration of short glass fiber reinforced polyamide 6 containing TiO2 was weakening of glass fibers.
