Polypropylene composite reinforced with fibrillated curaua fiber and using maleic anhydride as coupling agent

Curaua fibers (CF) were fibrillated using high-intensity ultrasonication, which is fast and uses water as a solvent. The fibrillated fibers (CFf) were used as reinforcement (20 wt %) in polypropylene composites processed by extrusion with or without 2 wt % of polypropylene grafted with maleic anhydride (PPMA). Fibrillation promotes an increase from 11.3 to 33.8 in the aspect ratio of the fiber. Sonication caused extraction of lignin and a decrease in the degree of crystallinity of the CF. Extrusion of the composites causes no additional fibrillation of the CF. A composite reinforced with CFf had tensile and flexural strength of 24.9% and 51.5%, respectively, higher than that of pristine PP. The use of PPMA and CFf in the composite promotes a further increase of 30% and 50.5% in these parameters, respectively. A thermal analysis of the composites using CFf with or without PPMA showed similar behavior. (C) 2017 Wiley Periodicals, Inc. (AU)