Enhancement of interfacial compatibility and mechanical performance of polylactic acid/oil palm empty fruit bunch composites via anhydride treatment

The incompatibility between a hydrophilic lignocellulosic fiber and a hydrophobic polymer matrix is always one of the major challenges in the development of lignocellulosic polymer composites. In this study, oil palm empty fruit bunch (EFB) fiber was chemically treated using three different anhydrides, i.e., maleic anhydride (MAh), itaconic anhydride (IAh), and succinic anhydride (SAh). Treated fiber (20%) was added to PLA to study the effects of anhydride type, concentration, and hydroquinone addition (for MAh and IAh) on composite properties. The results showed that the composites made of MAh and IAh treated EFB exhibited a better flexural property as compared to SAh treated EFB. The mechanical properties of the composites were further enhanced by preventing premature polymerization of C = C bonds from the MAh and IAh treated EFB. However, the impact strength was affected, which may be due to an increase in the composite stiffness, while SAh showed an improvement in the sudden energy absorption. Morphology studies had shown the treatments had improved fiber dispersion and interfacial adhesion in the composites. Overall, MAh and IAh treated EFB, especially with hydroquinone, had significantly improved the mechanical and interfacial properties of PLA/EFB composites, whereas SAh treatment resulted in more balanced enhancements.