Influence of Almond Shell Content and Particle Size on Mechanical Properties of Starch-Based Biocomposites

Abstract

This work reports on the effect of the particle size of almond shell powder (ASP) filler on starch-based biodegradable polymer. Different size ranges of particles were studied: < 0.05 mm, 0.05–0.08 mm, 0.08–0.125 mm and 0.125–0.250 mm in biocomposites with 30 wt% ASP. Additionally, biocomposites with 5 wt%, 10 wt% and 20 wt% of filler were prepared with ASP of 0.08–0.125 mm particle size. Biocomposites were manufactured by extrusion-compounding, and test samples were produced by injection moulding with the aim to study mechanical and thermal properties. The possibility of implementing the developed biocomposites in traditional industries, such as toys or packaging was evaluated, as biodegradable materials have gained great industrial interest in recent years owing to the coming legislative requirements and/or due to customer demands. The addition of the ASP on the polymeric matrix increases the stiffness of the polymer and reduces the deformation at break, the impact strength and the thermal stability. On the other hand, the final natural aesthetics provided by the filler is highly appreciated by the manufacturers and consumers (Blasco in Consumer attitudes and toy trends for eco-babies and bio-parenting, Nuremberg, 2020; Baeza in Childcare trends 43–45, 2020). The results of the study showed that, the filler content had a more significant effect than the particle size on the mechanical properties of the biocomposites.