Polylactic-acid–starch-based polymer composite (PLA/TPS) has good thermal stability for biocomposites. However, the physical and mechanical properties of PLA/TPS do not meet the standards. It needed additives to enhance its physical and mechanical properties. The aim was to improve the physical and mechanical properties of PLA/thermoplastic starch using sucrose. In addition, this study evaluated the enhancement of thermal properties of PLA/thermoplastic starch using sucrose. This study used sucrose as an additive to enhance the PLA/TPS composite. The addition of sucrose inhibits the degradation of biocomposites. This means that thermal stability increases. The thermal stability increased because the degree of crystallinity increased with the addition of sucrose, which was also proven in the XRD result. The addition of sucrose caused the morphology of the biocomposite to have pores. The FESEM results showed that biocomposites with the addition of sucrose had pores and gaps. These gaps result from low adhesion between polymers, causing a decrease in the mechanical and physical properties of the sample. Based on the FTIR spectra, biocomposite PLA/TPS blends with the addition of sucrose still have many hydroxyl groups that will lead to attracting other molecules or ions, such as oxygen or water. This phenomenon affects the physical and mechanical properties of materials. The physical and mechanical properties increased with sucrose addition. The best composite was prepared using 3% sucrose. This is because sucrose has a crystalline structure that affects the properties of biocomposites. However, the addition of 3% sucrose was not as effective as that of neat PLA.

Polylactic Acid (PLA) is a biodegradable polymer, but the cost of PLA is not competitive compared to polyolefins. The development of bioplastic composites by blending PLA with spent coffee grounds (SCG) and thermoplastic starch (TPS) is an effective way to reduce the cost of PLA. This study aimed to investigate and evaluate the feasibility of using SCG to develop bioplastic composite materials with a blend of PLA and TPS. Bioplastics were fabricated with various SCG contents (5, 10, 15 wt%). The physical and mechanical characteristics of the bioplastic composite decreased as the SCG content increased owing to the higher aggregation caused by SCG dust. However, the bioplastics manufactured with the addition of SCG exhibited enhanced crystallinity, resulting in enhanced thermal properties compared to the composites without SCG. The best characteristics of bioplastics, obtained with a 5% SCG addition, were as follows: water vapor transmission rate of 1276 g d/m², water vapor permeability (WVP) of 1.86256 × 10⁻⁷ g/ms Pa, Young’s modulus of 420 MPa, elongation of 2.59%, and tensile strength of 5 MPa. Based on the results obtained, it can be concluded that the addition of SCG is not recommended for improving the physical and mechanical properties of bioplastics. However, owing to its large content of organic compounds, SCG represents a promising and low-cost functional material that can be exploited in the development of various value-added products.