Continuous-glass-fibre-reinforced polypropylene composites - II. Influence of maleic-anhydride modified polypropylene on fatigue behaviour

This study investigates the fatigue behaviour of continuous-glass-fibre-reinforced polypropylene composites, under longitudinal, shear and transverse loadings. In order to study the tension-tension fatigue behaviour under different failure modes, specimens are used with fibres oriented at 0, 10, +/- 45 and 90 degrees with the loading direction, respectively. The experiments are carried out on composites based on an isotactic-polypropylene (PP) and a blend of this homopolymer and maleic-anhydride modified polypropylene (MA-PR), the latter showing better interfacial bonding with the silanized E-glass fibres. Since the fatigue performance of composite materials is strongly determined by the matrix, the fatigue behaviour of pure matrix material is also investigated. Results indicated that improved adhesion in the glass/MA-PP composites has a positive effect on the damage development as measured by stiffness reduction during fatigue life. The fatigue sensitivity, i.e. the degree of reduction of fatigue strength with increasing life, is however not significantly affected by the matrix/interphase modification. (C) 1998 Elsevier Science Limited. All rights reserved.