Fracture and impact behaviour of solid phase formed polypropylene composites with long glass fibres

Solid phase forming is prominent in the processing of thermoplastic composites, but not much work has been done in this area. In the present study, the effect of fibre content and prestrain on the fracture and impact behaviour of solid phase formed glass–polypropylene composites was investigated. Fracture tests were conducted using specimens with three fibre contents (20, 30 and 40%). Impact tests were carried out with the application of three different fibre contents (20, 30 and 40%) and three levels of prestrain (10, 20 and 30%). After fracture and impact testing, SEM examination was carried out of the fracture surfaces to investigate the failure mechanism of the solid phase formed glass–polypropylene composites. The results showed that fracture toughness and impact strength increased with increasing fibre content. Fracture toughness and impact strength increased by ∼15% and ∼190%, respectively, when the fibre content was increased from 20 to 40%. The results also showed that, for fibre contents of 20 and 30%, the impact strength increased with increasing prestrain. For a fibre content of 40%, however, the impact strength increased until the prestrain reached , 10%, but decreased thereafter. Examination by SEM indicated that plastic deformation and matrix fracture played an important role in the case of low fibre content and prestrain. Fibre breakage and debonding functioned as dominant failure mechanisms in the case of high fibre content and prestrain.