Rotational Rheology of Wood Flour Composites Based on Recycled Polyethylene

In this work, highly filled composites made of a commercial polypropylene resin and low melting point Tin particles, up to 50 vol.% in loadings, have been prepared by melt blending process. The introduction of stearic acid (SA), a common dispersant, was investigated in compositions. The developed systems were characterized in terms of dynamic rheological testing. Final results confirmed a reduction of linear viscoelastic domain, by increasing filler loadings, with an effect more emphasized in the presence of SA. Contrary to literature studies, at equal filler content (50%), both moduli resulted to be superior for formulations containing the dispersing agent. A further rheological characterization continued on systems at 30 vol.% of particle loadings for highlighting differences depending on the SA addition. Specific tests were also performed at temperatures above the melting of Tin particles. Finally, optical microscopic analyses were carried out for gaining insight on sample microstructure, in controlled conditions of temperature and shear rate.