Characterisation of fibre–polymer interactions and transcrystallinity in short keratin fibre–polypropylene composites

Abstract

Short fibre reinforced composites were made from keratin fibres obtained from poultry feathers. The matrix material was either polypropylene or a blend of polypropylene and maleic anhydride modified polypropylene (MaPP). In general, the addition of MaPP to polypropylene (PP) did not alter the tensile properties of the blend in a significant way. When not using MaPP, composites had lower breaking stresses than samples without fibres. However, MaPP at concentrations of >4 wt-% enhanced the breaking stress of the composites to above the value without fibres. Concurrent thermal analysis using differential scanning calorimetry (DSC) showed a distinct increase in the amount of transcrystallinity in the composites at MaPP concentrations greater than 4 wt-%. Scanning electron microscopy (SEM) revealed increased interactions between the protein fibres and the PP/MaPP matrix. Annealing showed that more large polymer crystals near the fibres were not enough to increase stress transfer across the interface.