Abstract
<title>Abstract</title> <p>This study investigates the thermal degradation behavior and degradation kinetics of polylactic acid (PLA)/starch biocomposites reinforced with spider silk for sustainable packaging applications. Thermogravimetric analysis (TGA) was conducted under a nitrogen atmosphere at heating rates of 10, 15, and 20°C min⁻¹ to assess the impact of starch and spider silk on the thermal stability of PLA. The results revealed that the addition of starch decreased the thermal stability of PLA, leading to a reduction in the maximum degradation temperature (Tmax) from 386°C for neat PLA to 369°C for the PLA/starch blend. In contrast, the incorporation of spider silk enhanced thermal resistance, raising Tmax to 373°C and 383°C for composites with 1 wt% and 2 wt% spider silk, respectively. Moreover, spider silk promoted char formation, leading to increased residual mass following degradation. Degradation kinetics were evaluated utilizing the Flynn–Wall–Ozawa (FWO) and Kissinger methods to calculate the apparent activation energy (Ea). FWO analysis demonstrated conversion-dependent activation energies, showing that starch introduced heterogeneous multi-step degradation behavior, whereas spider silk raised the energy barrier for thermal decomposition by enhancing interfacial interactions and limiting chain mobility. Kissinger analysis exhibited a similar trend, validating the enhancement of thermal stability in the composites by spider silk reinforcement. Overall, the results demonstrate that spider silk effectively mitigates the thermally destabilizing effect of starch and serves as a promising bio-reinforcement for the development of thermally stable, biodegradable PLA-based composites suitable for sustainable packaging applications.</p>