AN INVESTIGATION OF GLASS-FIBER POLYPROPYLENE INTERFACE STRENGTH AND ITS EFFECT ON COMPOSITE PROPERTIES

The structure and properties of the fibre/matrix interface region play a major role in determining the performance of structural composites. One of the main factors which influences the interface region is the fibre surface coating applied by the manufacturer. The influence of these coatings on the interfacial strength of glass fibre/polypropylene composites has been evaluated using the single fibre pull-out test. Results indicate that silane coupling agent alone has little effect on the interfacial strength. However, in combination with some other component of the coating, significant effects were found. The level of glass fibre/polypropylene interfacial strength varied by an order of magnitude depending on the nature of the fibre coating. Furthermore, the flexural strength of a unidirectional glass-reinforced polypropylene laminate varied by a factor of two depending on the type of glass fibre coating. The flexural strength results correlated well with the level of interfacial shear strength as measured by the single fibre pull-out test. The interfacial shear strength could also be correlated with the level of fibre surface coverage given by the fibre coating as measured using X-ray photoelectron spectroscopy.