Keratin obtained from poultry feathers was extruded at 120°C using a combination of glycerol, water, and sodium sulfite as processing aids. Rheological properties were assessed as a function of water, glycerol, and sodium sulfite content as well as extruder die temperature. The lowest viscosity blends at a constant feather keratin concentration of 60 wt % were found at glycerol concentrations that were higher than the water concentration and sodium sulfite concentrations of 3-4 wt % of the feather keratin fraction. For the melt state, higher or lower sodium sulfite concentrations resulted in increased viscosity. In the solid state, it was observed that processing induced orientation increased the tensile properties of the extrudates. Raman spectroscopy and DSC showed that there was a transition from ␣-helix to ␤-sheet at sodium sulfite concentrations of less than 4 wt %. At greater sodium sulfite concentration, increased crystallinity was found, because keratin chains could be extended more during processing.

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.

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