Mechanical, physical and thermal properties of High Density Polyethylene (HDPE) composite filled with Azadirachta excelsa (Sentang) tree wastes flour / Aina Munirah Zakaria

Forest biomass in the form of leaves, branches, broken logs, barks and stumps are becoming one of the issues that can lead to the landfill without proper management. Efficient methods should be considered in order to minimize the volume and utilized it into a valuable product. In this study, wastes flour from different parts of Azadirachta excelsa (Sentang) tree such as leaves, branches and trunks were combined with high density polyethylene (HDPE) polymer as a matrix and maleic anhydride as a coupling agent in order to produce HDPE composite filled with Sentang waste flour. The HDPE composite tree waste flour; HDPE composite-filled leaf flour (HDPECL), HDPE composite-filled branch flour (HDPECB) and HDPE composite-filled trunk flour (HDPECT) consisted of 25%, 35% and 45% wastes flour respectively. These HDPE composite panels were manufactured using micro-injection moulding machine under the temperature of 190 ˚C. The mechanical, physical, thermal properties and microstructure of the HDPECL, HDPECB and HDPECT at different filler loading were analysed and compared with HDPE composite. The chemical composition of trunk, branch and leaf were identified in order to correlate with the mechanical, physical and thermal properties of HDPE composite. Result shows that HDPE composite-filled trunk at 45% (T45) filler loadings had better mechanical properties, thermal properties and morphology characteristics. T45 had the highest flexural modulus, flexural strength, tensile strength and hardness with 3822.8 MPa, 65.79 MPa, 27.91 MPa and 71.0 Shore D hardness. The high holocellulose and lignin content presents inside the trunk which is 85.5% and 49.6% contributes to the enhancement properties of the composites especially in mechanical and thermal properties. The presence of trunk and branch waste flours enhanced the properties of the composite because there is no significant in terms of mechanical properties between them. This is due to the chemical composition that found inside the trunk and branch which have almost the same composition. However, leaf waste flour showed no significant difference with HDPE composite, thus, the addition of leaf waste flour to the HDPE composite has not enhanced its properties. 45% filler loading shows the significant roles in mechanical and thermal properties as it exhibited better mechanical strength and thermal stability. However, it showed lower performance in terms of physical properties as it consists of lots of hydrophilic lignocellulosic fibers compared to others. Overall, HDPECT at 45% filler loading shows better performance compared to HDPECB and HDPECL.