Biocomposite consisting of miscanthus fiber and biodegradable binary blend matrix: compatibilization and performance evaluation

Biocomposites were fabricated from miscanthus fibers and a blend composed of poly(butylene succinate) (PBS)/poly(butylene adipate-co-terephthalate) (PBAT) matrix by extrusion and injection molding. Due to the reinforcing effect of miscanthus fibers, the tensile, flexural, and storage modulus of the composites were increased with increasing fiber content from 30 to 50 wt%. Young's modulus of the composite was evaluated by parallel, series, Hirsch and Halpin-Tsai models. It was found that the Hirsch model has good agreement with the experimental modulus of the composites. There was a sharp reduction in tensile strength and impact strength after the incorporation of miscanthus fibers into PBS/PBAT blend matrix. These reductions were due to the incompatibility between the fibers and the matrix. Therefore, maleic anhydride (MAH) functionalized PBS/PBAT blend was prepared and used as compatibilizer to improve the compatibility between the fibers and the matrix. The composites prepared with 5 wt% MAH functionalized compatibilizer showed significant improvement in mechanical properties compared to their uncompatibilized counterparts. The morphological analysis of the composites displayed good fiber-matrix interaction in the presence of compatibilizer whereas composites showed poor interface between the phases without compatibilizer. The shear thinning behavior of the composites was increased compared to neat PBS/PBAT blend. The increased shear thinning behavior of the composite was attributed to the reduced polymer chain entanglement in the presence of fibers. The miscanthus fibers reinforced PBS/PBAT composites can offer significant benefit in terms of economic competitiveness and functional performances.