Preparation of durable flame retardant PAN fabrics based on amidoximation and phosphorylation

Abstract

Abstract This paper aims to develop a method to impart polyacrylonitrile (PAN) fabric durable flame retadancy. PAN fabric was modified with hydroxylamine hydrochloride (HA) to prepare amidoxime PAN fabric (A-PAN) followed by phosphorylation with phosphoric acid (PA) to obtain flame retardant PAN fabric (P-A-PAN). Thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), microscale combustion calorimetry (MCC) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) were used to analyze the thermal degradation process and flame retardant mechanisms. The structure of the fabrics was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). The surface morphology of fabrics was observed by scanning electron microscope (SEM). Moreover, the flame retardancy of fabrics before and after washing was evaluated by Limiting oxygen index (LOI) and horizontal burning test. The results showed that the P-A-PAN possessed an excellent thermal stability with the highest LOI value of 34.1% and the highest char residue of 55.67% at 800 °C. Most importantly, the P-A-PAN possessed a wonderful flame retardant durability with a little decrease of LOI after 20 washing cycles. When they were ignited, the P-A-PAN fabrics before and after washing were both nonflammable due to the char residue formation of modified fabric.