Interlaminar fatigue crack propagation in continuous glass fiber/polypropylene composites

The mode II interlaminar fatigue crack propagation behavior of unidirectional continuous glass fiber (GF) composites with a polypropylene (PP) matrix obtained under three different molding conditions has been studied with the use of the end-notch flexure (ENF) geometry. The microstructure and mechanical performance, especially the interlaminar fatigue crack propagation, are strongly affected by the molding conditions. Comparative results reveal a major influence of the fiber–matrix interface and the matrix morphology on the crack propagation resistance. The distribution of the ductile amorphous PP phase in the semi-crystalline PP matrix appears to be the controlling parameter determining the fatigue crack propagation resistance of the PP/GF composite. Fractographic observations clearly showed the role of this phase.