Development of flexible composites from modified starch reinforced with coarse wool fibers: Processing, characterization and applications

The objective of the present study is to use low-grade coarse wool fibers for the development of environmentally friendly, biodegradable flexible composite materials. Thermoplastic corn starch (TPCS) was reinforced with coarse wool fibers at varying fibre loadings of 25%, 35%, and 45 wt% to make flexible composites. A needle punched nonwoven fabric was used to as a reinforcing material for composite fabrication. To improve water resistance, a thin polyurethane-based coating was applied on both sides of the developed composites. The reinforcing fibers were characterized for tensile properties, diameter, medullation and moisture content. The developed composites were evaluated for tensile test, tear resistance, folding endurance, water absorption, thickness swelling and thermal behavior using thermogravimetric analysis, limiting oxygen index (LOI) and vertical flammability tests. Morphological and chemical interactions were analyzed using SEM and FTIR techniques. Results revealed that composites with 45 wt% fiber content exhibited superior tensile strength (5.62 MPa in cross direction and 4.62 MPa in machine direction) compared to pure TPCS (2.9 MPa). The study demonstrates that coarse wool fiber-reinforced TPCS composites possess improved mechanical and functional properties, making them suitable for sustainable applications such as biodegradable packaging materials, flexible sheets, and eco-friendly textile-based products.