The effects of the aggregation structure parameters on impact-fractured surface fractal dimension and strain-energy release rate for polypropylene

By changing the distribution of polypropylene (PP) molecular weight, thermal treatment and adding a nucleation agent, the effects of crystallinity and spherulite size of polypropylene material on its impact-fracture surface fractal dimension and strain-energy release rate have been studied. It is shown by theoretical calculation and experiments that the larger the crystallinity and the spherulite size of PP material are, the smaller the fracture-surface fractal dimension and the strain-energy release rate. The effect of the nucleating agent, molecular weight distribution (MWD) and thermal treatment on the strain-energy release rate is brought about by a change in the aggregation structure parameters of PP.