The Influence of Varying Polymer Matrices on the Mechanical Properties of Biocomposites

The mechanical properties of oil palm empty fruit bunch (OPEFB) filled composites based on two (2) types of polymer matrices, high-density polyethylene (HDPE) and low-density polyethylene (LDPE) were studied. The EFB content was varied from 0, 10, 20 to 30 wt%. EFB in the form of particulate (0.325 – 0.4 mm) was treated with 3 wt% of vinyltriethoxysilane (VTS) coupling agent. Scanning electron microscope (SEM) micrographs revealed rough and more texturized surface after the EFB was being treated. Subsequently, EFB was compounded and molded with HDPE and LDPE using injection molding machine to produce dog-bone shaped specimens for tensile and flexural testing. Generally, tensile strength for HDPE-EFB was higher than LDPE-EFB which was due to the low degree of branching in HDPE molecules with higher intermolecular forces and higher tensile strength. However, both HDPE-EFB and LDPE-EFB showed a decreasing trend as the EFB content increased from 0 to 30%wt. In the case of flexural strength, HDPE-EFB also recorded higher results when compared to LDPE-EFB due to the fact that HDPE molecules packed into crystal structures with higher intermolecular forces to resist deformation. Additionally, both HDPE-EFB and LDPE-EFB demonstrated an increment as the EFB content increased. At the microstructural level, SEM micrographs of the fractured specimens showed that the composites were filled with voids and the tensile failure occurred due to poor wetting of filler.