STUDIES ON MECHANICAL, BIODEGRADABILITY AND WATER ABSORPTION CHARACTERIZATION OF STARCH-BASED PACKAGING FILMS FORMULATED FROM AGRICULTURAL WASTES

Abstract

Biodegradable polymers derived from agricultural wastes are increasingly favoured over synthetic petroleum-based plastics owing to their sustainability, renewability, biodegradability, low toxicity and cost-effectiveness. Some studies emphasize structural characterization while paying less attention to the mechanical, biodegradability and water absorption performance of the final product. This study evaluated the mechanical properties, biodegradability and water absorption behaviour of starch-based biodegradable packaging films formulated from a composite of yam peels, potato peels and sugarcane bagasse. The Starch was extracted from the samples using a wet milling method, and biodegradable films were formulated through gelatinization, glycerol plasticization, pH adjustment with acetic acid and calcium chloride crosslinking. Mechanical characterization revealed a tensile strength of 8.42 ± 0.58 MPa, elongation at break of 42.76 ± 4.21%, Young's modulus of 186.35 ± 18.47 MPa, tear strength of 1,284 ± 96 gf (MD) and 1,167 ± 88 gf (TD) and fold endurance of 74 ± 9 double folds. Soil burial test over 12 weeks demonstrated progressive biodegradation of the TPS film, with weight loss increasing from 18.42% (week 3) to 37.65% (week 6), 56.89% (week 9) and 74.23% (week 12), while the LDPE control remained essentially intact with only 0.79% weight loss. FTIR of the biodegraded polymer confirmed molecular-level degradation: O–H stretching shifted from 3284 to 3274 cm⁻¹, a new carbonyl C=O band appeared at 1716 cm⁻¹ indicating oxidative degradation products, the C–O–C band shifted from 1154 to 1150 cm⁻¹ indicating glycosidic cleavage, and the C–O band at 1080 cm⁻¹ disappeared entirely. The water absorption test showed that the TPS film absorbed 32.20% water after 24 hours, compared to only 0.40% for LDPE. Absorption increased progressively from 8.40% (3 h) to 15.60% (6 h), 24.80% (12 h) and 32.20% (24 h), consistent with the bulk absorption mechanism characteristic of starch-based materials. The combined mechanical, biodegradability and water absorption evidence confirms that starch-based films from agricultural wastes are viable biodegradable alternatives to conventional petroleum-based packaging materials.