Milling Time Effects on the Thermal Degradation, Density, and Porosity of Coconut Shell-Reinforced Epoxy Biocomposites

Polymer biocomposites are sustainable and environmentally friendly materials that can be applied to the building, furniture, aerospace, and automotive industries. In this study, biocomposites made of coconut shell-reinforced epoxy resin were prepared and characterised. Initially, the coconut shells were 200 mesh. Then, they were milled by using a ball mill for 10, 20, 30, and 40 h. The biocomposites were manufactured by using a compression method while keeping a constant ratio of filler and matrix at 85 vol.%: 15 vol.%. The effects of ball milling duration on the thermal degradation and physical properties of biocomposites were examined. The thermal degradation of coconut shell biocomposite occurred at 250 – 400 °C. Its thermal degradation temperature increased with the increasing milling times. The density of the coconut shell biocomposite was 1.087 g/cm3 for 0 h (without milling the fillers). Its density increased to 1.248 g/cm3 for 40 h of milling duration. Meanwhile, the porosity of coconut shell biocomposite decreased from 17.5% (0 h milling duration) to 12.1% (40 h milling duration). It was found that there was a correlation between thermal degradation and physical properties (density and porosity). This study revealed that the thermal degradation and physical properties of the biocomposites can be enhanced by decreasing the size of the fillers.