Reinforcement potential of miscanthus post-harvest dust for polymer composites
Résumé
In the last decades, the interest in using biomass in polymer composites has largely grown. Lignocellulosic fragments present lower density compared to conventional reinforcements, such as glass fibers, leading to lighter manufactured materials and displaying competitive mechanical properties. Moreover, they come from renewable resources, are non-toxic and usually environmentally friendly. The mechanical properties of biomass-reinforced composites are controlled by the efficiency of the stress transmission from the polymer matrix to the fragments. It depends on the biomass/matrix adhesion, fragments dispersion and distribution in the matrix, the type and composition of the biomass and their morphology (length L, diameter D, aspect ratio L/D). The latter are, in turn, strongly affected by compounding conditions. Hence, well-defined length distribution and initial fragments size are determined in order to maximize composite properties. Owing to these constrains, a large amount of biomass material remains left over because not considered suitable for industrial applications. In this work, we investigated the mechanical properties of polypropylene composites reinforced with miscanthus post-harvest dust and the influence of fragment size distribution. The goal is to understand the reinforcement potential of this biomass product and, possibly to maximize it by adapting the fragment size distribution. Miscanthus biomass have been mixed with polypropylene (PP) and a fragment/matrix compatibilizer (MA-g-PP) is added to improve the interfacial adhesion between biomass and polymer matrix. The compounding mixing conditions (rotors speed, mixing time, temperature) are kept constant, while biomass concentration is varied systematically (from 20 to 50 wt.%), and its size distribution as well. Length and diameter measurements are obtained using a high-resolution 2D scanner.