REDUCTION OF STIFFNESS IN 100% POLYESTER WOVEN FABRICS USING COCONUT OIL DERIVED BIO-SOFTENER: A SUSTAINABLE FINISHING APPROACH

Abstract

Polyester fabrics, though valued for their strength, dimensional stability, and low maintenance, are often criticised for their stiffness and poor comfort when used in apparel worn next to the skin. Conventional chemical softeners, typically petroleum-based, are non-biodegradable and raise environmental and health concerns. This study investigated the feasibility of using coconut oil–based BIO- softener as a sustainable alternative for 100% virgin polyester woven fabrics. Softener emulsions were prepared with food-grade coconut oil, Polysorbate 80 as a non-ionic emulsifier, and citric acid as a pH adjuster, at concentrations of 2%, 5%, and 10% (w/w). Fabric samples were treated using a dip-squeeze-air dry method and evaluated for drapability (ISO 9073), stiffness (ASTM D1388), tensile strength (ISO 13934-1), fabric weight (GSM), and surface pH, with wash durability tested according to ISO 105-C01. For each test, three readings per sample were taken, and mean values were used for analysis. Results indicated that increasing BIO-softener concentration reduced stiffness and improved flexibility, with the 10% treatment giving the highest and most balanced improvement. Drapability improved by lowering the drape coefficient by 14.77%, while flexural rigidity reduced by 22.86% in the warp and 23.08% in the weft directions. GSM increased proportionally with softener concentration due to surface film deposition, but remained above untreated values even after washing, confirming acceptable durability. All treated fabrics maintained skin-safe surface pH (7.0–7.3). At the 95% significance level, tensile strength in the warp direction increased consistently and significantly (p < 0.05), while weft changes were minor and statistically insignificant (p > 0.05); the 10% treatment showed the greatest improvement in both directions. Concentrations above 10% led to undesirable oiliness and non-uniform appearance, limiting practical application. In conclusion, coconut oil–based BIO-softener proved effective in enhancing drapability and flexibility of polyester fabrics while maintaining mechanical integrity, wash durability, and wearer safety. Future studies should include thermal comfort and subjective hand-feel assessments for a more holistic evaluation of fabric performance. These findings confirm its potential as an eco-friendly alternative to petroleum-based softeners, supporting sustainable finishing practices for synthetic textiles.