Development of Starch-based Biodegradable Plastics reinforced with Natural Fiber for enhanced mechanical and biodegradation properties

Abstract

This study investigates the development of starch-based biodegradable plastic composites reinforced with kenaf fibre to improve mechanical performance and biodegradation. Starch was extracted from plant sources, and kenaf fibres were chemically treated prior to composite fabrication to improve interfacial compatibility. Composite films were produced from starch, glycerol, and varying kenaf fibre contents using optimized formulations derived from response surface methodology. Structural and physicochemical characterizations of the treated fibres and composites were conducted using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) to evaluate functional group interactions and crystalline structures. Film density and water absorption were evaluated in accordance with ASTM D792 and ASTM D570, respectively, while chemical resistance was assessed in accordance with ASTM D543-95. Composite density ranged from 0.87 to 1.45 g/cm³, with higher values observed at increased kenaf fiber content, demonstrating the influence of formulation on composite structure. Film thickness ranged from 2.84 to 4.85 mm, with higher glycerol content increasing thickness and fiber addition contributing to improved dimensional uniformity. Mechanical testing showed that kenaf fiber reinforcement enhanced tensile strength to 22.91 MPa, elongation at break to 59.42%, and Young’s modulus to 322.46 MPa. Water absorption measured according to ASTM D570 reached 85.20%, reflecting the hydrophilic nature of the starch matrix. Biodegradation studies using a soil burial method showed effective microbial degradation, with percentage weight loss ranging from 18.03% to 91.70%. Thermal analyses (DSC and TGA) revealed improved thermal stability for kenaf-reinforced composites, with crystallization and melting temperatures of approximately 250 °C and 340 °C, respectively. Overall, kenaf fiber reinforcement significantly enhanced the mechanical properties, thermal stability, chemical resistance, and biodegradability of starch-based bioplastics, highlighting their potential as sustainable alternatives to conventional plastics.