A halogen-free flame retardant with P/N and optimization for cotton fabrics tensile properties

Cotton fibers' flammability and rapid combustion greatly restrict their usage in industries that require higher flame retardancy. Phosphorus and nitrogen-based flame retardants are frequently employed in the textile industry to consolidate the flame resistance of cotton materials. To consolidate flame retardant performance, a novel flame retardant named HPAPU was synthesized by combining 3-hydroxyphenylphosphinylpropionic acid, 1,6-hexanediamine, phosphoric acid, and urea. The structure of the products at each step was analyzed using Fourier transform infrared spectroscopy. In addition, the NMR was utilized to confirm that it was successfully synthesized. In order to evaluate the flame retardancy of HPAPU-treated cotton fabrics, the limiting oxygen index (LOI) was measured. The results showed that the LOI of the cotton fabric with 27.5 % weight gain was 38.5 %, which is a significant increase compared to the pure cotton fabric. According to the cone calorimeter test, the HPAPU-treated cotton fabrics showed a decrease in 86.6 % in peak heat release rate and 41.67 % in peak total heat release rate compared with unprocessed samples. In the tensile test, we found that increasing the flame-retardant concentration can improve the fabrics' tensile strength.