Mechanical properties of hybrid sisal/coir fibers reinforced polylactide biocomposites

Untreated sisal and coir fibers (USF and UCF), alkali-treated sisal and coir fibers (ASF and ACF), and alkali-treated sisal/coir hybrid fibers (ASF/ACF) reinforced polylactide (PLA) composites were prepared by compression molding technique. The materials were characterized in terms of tensile, flexural, and impact properties. While all mechanical tests showed that the composites reinforced by alkali-treated fibers could withstand more fracture strain than untreated fibers reinforced composites which could be attributed to the improved interfacial adhesion between alkali-treated fibers and matrix related to the remove of lignin, hemicellulose and pectin by the alkali treatment, the addition of ACF in PLA/ASF composites improved the impact strength of PLA/ASF/ACF composites and showed a positive effect. More fibers tended to be torn apart or fractured, but less pulled out with the increase of coir fiber content. Compared to other composites, the ASF/ACF-reinforced PLA composites offered superior mechanical properties when the ratio of sisal to coir was 7:3. POLYM. COMPOS., 39:E188-E199, 2018. (c) 2017 Society of Plastics Engineers