Fabrication and Characterization of Starch/PVA Blend Films Reinforced With Black Tea for Packaging Applications

Abstract

Conventional petroleum-based plastics, with annual global production exceeding 400 million metric tons, pose severe environmental challenges due to their nonbiodegradable nature and persistent pollution, necessitating innovative bio-based derived alternatives. This study addresses this need by developing bioplastic films through solution casting of potato peel starch and polyvinyl alcohol (PVA) reinforced with black tea waste extract (BTWE) at 0.5%–2.0% w/v, using glycerol as a plasticizer. BTWE was characterized via GC–MS, revealing 44 bioactive compounds, including 2-hydroxymethyl-5-furfural (34.02%) and caffeine (9.29%). Films were comprehensively evaluated for mechanical, barrier, optical, friction, migration, and structural properties using standardized ASTM/ISO methods. Key findings demonstrate concentration-dependent enhancements: tensile strength increased from 8.35 MPa (control) to 13.42 MPa (2.0% BTWE), approaching LDPE (10–21 MPa); burst strength peaked at 3.95 kg/cm² (1.0% BTWE), matching commercial standards (2–5 kg/cm²); and elongation reached 692% for flexibility. Water absorption was minimized to 118.07% (1.5% BTWE vs. 155.92% control) through polyphenol-polymer hydrogen bonding; migration stayed below 1.79 mg/dm², compliant with EU limits (10 mg/dm²); and thickness increased from 0.124 to 0.152 mm. SEM revealed progressive surface roughness uniformity, while FTIR confirmed strengthened hydrogen bonds; the 1.5% BTWE formulation optimized performance. Overall, this work offers a scalable, eco-efficient, and scientifically robust strategy for transforming biowaste into high-quality bioplastic films for advanced packaging applications, thereby contributing meaningfully to environmental stewardship and materials innovation.