Micromechanics of lignin/polypropylene composites suitable for industrial applications

Abstract

Lignin/polypropylene composites were compounded by melt blending in a thermokinetic mixer and then ASTM specimens suitable for tensile testing were made by injection moulding. Two polypropylenes with different molecular weights were used as matrices. Lignin contents in the composites ranged from 10 to 55 wt.-%. Tensile modulus, strength and elongation were determined for those composites. The experimental data thus obtained were thus mathematically fitted to several micromechanical models. Micromechanical models best suited for fitting experimental data were those of Halpin-Tsai, Nielsen and Pukánszky. Fitting of predicted data to the experimental data was good in most cases, thus revealing the ability of those models for predicting the tensile properties of lignin/polypropylene composites and estimate the unknown modulus of elasticity of the lignin used as filler.