Hemp Strands: PP Composites by Injection Molding: Effect of Low Cost Physico-chemical Treatments

Abstract

Hemp strands as natural lignocellulosic fibers are used to reinforce polypropylene composites obtained by injection molding. The aim of this work is to improve the final mechanical properties using simple and cheap treatments. Therefore, a refining process is applied to increase the specific surface and the fibrillation of hemp strands resulting in a better mechanical anchoring and adhesion with the matrix. The hydrophilic nature of the hemp strands is diminished by surface chemical treatment with alkyl ketene dimmer (AKD) in aqueous media. Final mechanical properties of hemp composites are studied and compared to those of glass fiber reinforced polypropylene composites. The fiber length and diameter of fiber reinforcement during processing are also analyzed. The results thus obtained show that the specific mechanical properties at yield of hemp composites may increase 80% of the mechanical properties of glass fiber composites.