アニール処理をした非充填および短繊維充填ポリプロピレンの破壊の様相

概要

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Fracture mechanisms of unfilled (N-PP) and short glass fiber filled polypropylene (GF-PP) were studied with particular attention to the effect of temperature and annealing on the fracture morphology. Optical and scanning electron microscope observations were made for fractured compact tension specimens. In a temperature range from -60°C to 23°C, a low speed fracture zone appeared on the fracture surfaces of N-PP. The zone increased in area almost linearly with an increase of logarithmic value of the fracture toughness (Jm). On a surface region near the crack tip of loaded GF-PP specimens, whitening was observed and its area had a linear relation with logarithmic toughness value. The slope of the linearity changed considerably below and above the temperature range of -30°C∼0°C. The glass transition temperature of PP resin was about -15°C. Annealing of N-PP specimens caused a change in propagation mode from a branching type to a straight type, whereas for GF-PP it caused to generate rather flat fracture surfaces.