Development and characterization of cassava starch-coated biodegradable packaging sheets from corn husk, corn silk, cassava peel, and banana peel waste

Abstract

The accumulation of petroleum-derived single-use plastic packaging has created a strong need for biodegradable materials from renewable, low-cost resources. This study developed biodegradable packaging sheets coated with cassava starch using corn husk, corn silk, cassava peel, and banana peel waste. The raw materials were washed, cut, alkaline-pulped with sodium carbonate, blended into a homogeneous pulp, and formulated into three treatments by varying corn husk content (T1: 100 g, T2: 200 g, and T3: 300 g), while cassava peel, banana peel, and corn silk were kept constant. Bentonite, rosin-alum, and over-matured okra mucilage were incorporated to improve sheet formation and bonding. The molded sheets were sun-dried and coated on both surfaces with a cassava starch-polyvinyl alcohol bioplastic coating plasticised with glycerol. The developed sheets were evaluated for moisture content, water absorption, thickness, grammage, tensile strength, solubility, and soil-burial biodegradability. Significant treatment effects (p < 0.05) were observed for the major physical and mechanical properties. T3 showed the highest thickness (1.926 ± 0.029 mm), grammage (617.7 ± 16.41 g/m²), moisture content (7.163 ± 0.150%), water absorption (385.5 ± 11.42%), and tensile strength (2.1067 ± 0.03 MPa). However, biodegradation was fastest in T1, which reached 63.33 ± 2.00% weight loss after 49 days, compared with 52.00 ± 2.00% for T2 and 37.33 ± 2.00% for T3. All treatments showed low solubility (<4%) in distilled water, acetic acid, sodium hydroxide, and ethanol after 24 h immersion. The results indicate that agricultural wastes can be converted into biodegradable single-use packaging sheets, with T3 offering better structural performance and T1 showing faster environmental degradation. Further hydrophobic coating optimization is recommended for wet food-contact applications.