The Interlaminar Fracture Properties of Fibre Reinforced Thermoplastic Composites:The Efect of Processing Temperature and Time

An experimental study has been conducted to study the effect of processing temperature and dwell time on the critical energy release rate, Gc of unidirectional carbon fibre-reinforced poly ether imide (CF/PEI) under Mode II and Mixed-Mode I/II loading. Under Mode II loading, the value of GIIc, increased as a function of both processing temperature as well as with dwell time at the required temperature. A linear relationship was observed between the value of GIIc and the logarithm of the dwell time, t. Under Mixed-Mode loading conditions, the R-curves showed a continuous increase in the value of GI/IIC as a function of crack length, possibly due to the effect of fibre bridging. A comparison between the fracture toughness under Mode II shear loading and Mixed-Mode I/II loading indicated that Mode II loading yielded higher fracture energies for the same temperature and dwell time, possibly due to the occurrence of additional toughening mechanisms. The results suggest that the optimum processing temperature and dwell time for this material are 300°C and 60 minutes respectively. It is planned that these processing parameters will be employed in the repair of impact-damaged panels based on this thermoplastic material