The increasing concern about global warming and the accumulation of non-biodegradable plastic has caused serious environmental issues. Hence, the need to create a more environmentally friendly material such as thermoplastic starch (TPS) has grown. However, the poor properties of TPS, such as high moisture sensitivity and low mechanical properties, have limited the potential application of this biopolymer. This study aims to modify TPS’s thermal and mechanical properties by incorporating coconut fiber. The composites were prepared by incorporating various coconut fiber loading (0, 10, 20, 30, 40, and 50 wt.%) into the TPS matrix. The mixture was fabricated using a hot press at 145°C for 1 hour. The sample is then characterized using thermogravimetric analysis and tensile and flexural tests. The results show that the composite with 50 wt.% coconut fiber had higher thermal stability than samples with lower fiber content. A significant increment in tensile strength and modulus of up to 20.7 MPa and 2890 MPa were recorded for samples with 50 wt.% fiber content—the sample with 50 wt.% fiber also demonstrated the highest flexural strength and modulus of up to 30.3 MPa and 3266.3 MPa, respectively. These changes are consistent with the FTIR and SEM findings, which show good compatibility of TPCS and coconut fiber with a homogeneous structure. Overall, coconut fiber shows good potential as reinforcement for biodegradable-based polymer composites.

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