<![CDATA[The development of biodegradable plastics with tunable performance is critical for replacing petroleum-based polymers in engineering applications. This study systematically compares tapioca-starch-based bioplastics reinforced with Pandanus amaryllifolius (PA) and Cyclea barbata Miers (CBM) extracts to elucidate their structure–property–degradation relationships. Bioplastic films were fabricated via solution casting and characterized through mechanical testing, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), soil-burial biodegradation tests, and scanning electron microscopy (SEM). The results show that pandan–tapioca films (PTF) exhibit higher tensile strength and Young’s modulus, which are likely associated with the presence of lignocellulosic constituents in the pandan-derived extract and a more compact microstructural organization. In contrast, grass-jelly–tapioca films (GTF) demonstrate higher elongation at break, which may be related to the presence of water-soluble polysaccharide constituents in the CBM-derived extract that promote greater polymer-chain mobility. Differences in intermolecular interactions and morphology directly govern thermal resistance and degradation behavior, with PTF showing controlled degradation and GTF exhibiting rapid environmental breakdown. These findings establish a comparative materials-design framework for tailoring starch-based bioplastics toward specific mechanical durability and service-life requirements.]]>
