The fire performance of polyamide66 fabric coated with soybean protein isolation

Abstract

It has been a big challenge to produce sustainable environmental-friendly flame- retardant synthetic textiles for many years. In this work, soybean protein isolation in association with thiourea was coated on the surface of fibers through a simple pad-dry process in order to prepare flame retardant polyamide 66 (PA66) fabric with reduced environmental hazard and fire risk. The chemical components and the morphology of the treated fabric surface were analyzed by a Fourier transform infrared spectrometer and a scanning electron microscopy respectively. The flammability evaluation by limiting oxygen index (LOI) and vertical burning tests indicated that the LOI value was increased from 20.5–25.5, the damaged char length was reduced to only 4 cm, and the dripping phenomenon was eliminated for the coated PA66 fabric sample by the presence of protein/thiourea. It was demonstrated that the deposited protein/thiourea combination coating significantly improved the fire hazard resistance through affecting the thermal degradation pathway of PA66 fabric. It was proposed that oxygen and flammable gases in the gas phase be diluted by the released H2S, NH3, H2O gases, and compact char formation be promoted by the formed unsaturated double bonds (such as -C = N) during the burning process of PA66-SPI-thiourea samples. It was suggested the sustainable bio-based SPI could be an effective alternative to conventional flame retardants used in textile finishing.