The influence of glass fiber on fracture behavior of isotactic polypropylene

This study is focused on the role of glass fiber on the fracture mechanism in PP/GF composites. Several composites with different amounts of glass fiber were examined. Three-point and four-point bending tests were carried out. The results of three-point bending tests show that the fracture toughness of PP increases with the increase of GF content. The results of four-point bending tests display a wide spread damage zone in front of the pre-crack while optical photographs appears that the damage zone including craze which is initiated from glass fibres. Also, the observation of the damage zone utilizing cross-polarized light illustrates that there is no evidence of shear yielding phenomenon. Looking at this in more detail via scanning electron microscopy shows that the craze propagation can be dictated by glass fiber. The crazes in PP/GF composite, studied in this work, are propagated by moving towards the interface followed by craze thickening and fiber breakage.