Crystallization of polypropylene in the presence of Miscanthus x giganteus stems fragments

Abstract : Miscanthus Giganteus – reinforced polypropylene composites have been prepared by internal mixing. The effect of the size of the miscanthus fragments used as fillers onto the thermal properties of composites has been evaluated by differential scanning calorimetry (DSC) and polarized light optical microscopy (POM). The kinetics of the crystallization processes have been evaluated by isothermal methods. The influence of the fiber‐matrix interface onto the melting/crystallization processes has been evaluated by adding a maleic anhydride–grafted polypropylene (MA‐g‐PP) coupling agent. A clear acceleration of the crystallization kinetics was observed in the presence of miscanthus stem fragments. However, the results showed that, for non‐coupled composites, the size and aspect ratio of those fragments had no significant influence onto the crystallization kinetics of polypropylene. The presence of the MA‐g‐PP coupling agent increased the kinetics and reduced the crystallization activation energy. Although relatively small, if a good fiber‐matrix interface is achieved, the size of the filler plays a significant role onto the crystallization kinetics of the matrix, with smaller fragment leading to faster kinetics and reduced activation energy