Optimization of the mechanical properties of polyester/coconut shell ash (CSA) composite for light-weight engineering applications

The mechanical properties of coconut shell ash (CSA) reinforced polyester composite have been optimized. Various test specimens were developed by dispersing 10, 20, 30 and 40 wt.%, of CSA in unsaturated polyester resin in decreasing particle sizes of 40, 30, and 20 µm in an open mould using hand lay-up technique. Tensile, flexural, and impact strengths, as well as tensile and flexural moduli and Shore D hardness of all test samples were determined. The results showed that 10–20 wt.% CSA increased tensile, flexural, impact strengths and flexural modulus for all particle sizes, but 30–40 wt. % CSA engendered depreciation in corresponding performance. For all particle sizes, 10–40 wt. percent CSA resulted in an increase in tensile strength, whereas 10–40 wt. percent resulted into a linear increase in Shore D hardness. Further observation portrayed that in each case, the finest CSA (20 µm) have the optimum result. Statistical analysis carried out on experimental outcomes confirmed the experimental variables (particle proportion and sizes) to be significant. From the surface plot, the strength responses revealed more dependence on the individual variables than their interactions. Regression models developed for individual responses are termed statistically fit in representing the experimental data.