The morphology, character and strength of the interface in glass fibre-polypropylene composites

Abstract

The interface in clean glass fibre-polypropylene and silane-treated glass fibre-polypropylene pull-out specimens has been studied. The nature of the silane layer on the treated fibres was examined and the influence of agglomerates in the silane layer on the nucleating ability of the fibre surface has been considered. Transcrystalline sheaths of polypropylene were observed in the water-quenched samples but not the air-cooled and 50 °C oven-cooled samples. The nature of the interface and the plane of failure have been determined utilizing optical microscopy and scanning electron microscopy of both the fibre and matrix-failure surfaces. The shrinkage stresses in the air-cooled and oven-cooled clean fibre specimens were relieved by the formation of kink bands. The results suggest the existence of an interphase. The different interfacial strengths in the silane-treated and clean fibre specimens can be explained in terms of the above findings.