Flame Retardant Finishing of Cotton Fleece Fabric: Part IV-Bifunctional Carboxylic Acids

Abstract

Most cotton fleece fabrics are not able to meet the federal flammability standard for general apparel (16 CFR 1610). In this research, we applied three carboxylic acids, i.e., succinic acid (SUA), malic acid (MLA), and tartaric acid (TTA), as flame retardant finishing systems for cotton fleece. We found that all three acids are able to esterify cotton in the presence of sodium hypophosphite as the catalyst, and SUA is the most reactive and the most hydrolysis-resistant when it is bound to cotton. The a-hydroxyl group with both MLA and TTA appears to hinder esterification and to facilitate hydrolysis for MLA and TTA bound to cotton. All three bifunctional carboxylic acids are effective in reducing the flammability of cotton fleece from ‘Class 3’ to ‘Class 1’. The micro-scale combustion calorimetry data reveal that SUA reduces cotton flammability by reducing its peak heat-release rate and heat-release capacity. The cotton fleece treated with SUA also has the highest bursting-strength retention and the least fabric yellowing.