Lignocellulosic fibers: a critical review of the extrusion process for enhancement of the properties of natural fiber composites

Abstract

Natural fiber composites have various applications, since they can bring interesting mechanical and sustainability properties. Extrusion with a single- or twin-screw is the main industrial process to incorporate lignocellulosic fibers into polymers. In this review, the origin and preparation of lignocellulosic fibers are first presented, before discussing the composite processing, with a particular emphasis on the impact of process conditions on the composites final properties that is highly related to the final application. A broad panel of composites reinforced with lignocellulosic fibers is reviewed along with their polymeric matrix, lignocellulosic fiber type and pretreatments, and extrusion process conditions. Finally, the most critical extrusion process parameters (screw profile, speed and temperature) are also examined in order to determine some guidelines to optimize lignocellulosic fiber composites preparation.