Ammonium poly phosphate PIN FR effective for durable fire safety for Varanasi brocade woven from waste pineapple fibres. Indian handloom Varanasi textiles are >80% exported so must meet fire safety standards. Secondary pineapple cellulose fibres can replace cotton, providing a sustainable, locally sourced and economically attractive material, but must be fire safety treated. Ammonium polyphosphate (APP, a phosphorus-nitrogen inorganic salt PIN flame retardant) was dissolved in water then applied to the pineapple-fibre fabrics with cyanoguanidine catalyst by soaking, curing at 150°C, rinsing then drying. Application of 15% APP, 5% catalyst resulted in a 9% weight gain and increased N and P content of the fabric from near zero (untreated fabric) to 12% and 5% respectively. LOI was doubled, peak heat release rate was reduced by 98%, and there was no after-flame in vertical burn test. LOI remained > one third increased after 20 washes and there was no colour impact on the fabric. APP is considered to bind to the OH group of pineapple cellulose and to reduce flammability by intumescence, char formation and release of gas phase radicals.
“Application of ammonium polyphosphate as intumescent flame retardant on Varanasi brocade pineapple fabric”, A. Kushwaha et al., Biomass Conversion and Biorefinery 2023 https://doi.org/10.1007/s13399-023-04274-x