Influence of reprocessing on properties of short fibre-reinforced polycarbonate

The influence of reprocessing by injection moulding on properties of polycarbonate has been studied. It was found that reprocessing reduces the mean fibre length and increases the melt flow index. There was no variation in tensile or flexural properties with the number of reprocessing cycles. Fracture toughness, K-c, measured via notched tensile and flexural bars indicated that the material toughness is affected by the number of reprocessing cycles. The effect was more pronounced in bending than in tension. Strain energy release rate, G(c), was found not to be affected significantly by the number of reprocessing cycles. Although, as the material was reprocessed, fracture parameters were always lower than that of the virgin unprocessed material. The influence of reprocessing on weld-line properties was also investigated using notched tensile specimens. It was found that whereas tensile strength is not affected by the presence of the weld-line, fracture toughness deteriorated significantly, giving a weld-line integrity factor, F, of 0.75. The value of F was not affected significantly by the number of reprocessing cycles.