ガラス繊維強化シンジオタックチックポリスチレン（GF-SPS）切欠平板の破壊強度に及ぼす温度および引張速度の影響

抄録

The effects of environmental temperature and tensile speed on the fracture of notched plates of glass-fiber-reinforced syndiotactic polystyrene (GF-SPS) were investigated. Since GF-SPS has high heat resistance, it is expected to be a useful material at high temperature. In this study, GF-SPS plates containing 30 % E-glass fiber by weight were prepared by injection molding. The notch radii were 0.5, 1, and 2 mm, while the notch depth ranged from 2 to 5 mm. The tensile test was carried out at 23, 40, 60, 80, 100, and 120 °C with a constant crosshead speed. The effect of the notch geometry on the tensile strength decreased as the environmental temperature increased. Furthermore, at ≥ 80 °C, the maximum nominal stress of notched specimen was approximately equal to that of the smooth specimen. At ≤ 60 °C, the specimen failed in a brittle manner at the maximum load. Tensile tests were performed in this temperature range at tensile speeds of 10², 1, 8.33 x 10^-3, 8.33 x 10^-4, and 8.33 x 10^-5 mm/s. In case of the same temperature, the maximum elastic stress at fracture was determined from the notch-root radius and the time to fracture but it was independent of the notch depth. It was verified that a fracture criterion based on the severity of the stress fields near the notch roots was applicable in this temperature range. Furthermore, a log-log plot of the maximum elastic stress at fracture versus the time to fracture displayed a straight line and it can be presumed that the slope of the line is the same as that of the plot representing the data obtained at 23 °C.