A novel flame retardant with reactive ammonium phosphate groups and polymerizing ability for preparing durable flame retardant and stiff cotton fabric

A novel flame-retardant ammonium salt of cholamine (methylenephosphonic acid) ethylene-organic phosphate acid (ACMPEP) with reactive -P=O(ONH4)(2) and -OH groups was synthesized and characterized using nuclear magnetic resonance spectroscopy. The flame retardant not only could be grafted onto cotton fibers through P-O-C covalent bonds, but also react with each other to form poly-ACMPEP. The results showed that the finished cotton fabrics have excellent flame retardance, good stiffness and durability. The limiting oxygen index (LOI) value of 30% ACMPEP-treated cotton was 42.0%, and after 50 laundering cycles, the LOI value still had 30.0%. Thermogravimetric analysis (TGA) results showed that the decomposition temperature of treated cotton fibers in N-2 and air was 253 degrees C and 247 degrees C, lower than that of the control cotton fibers. Additionally, thermogravimetric-Fourier transform infrared (TG-FTIR) spectroscopy analysis indicated that the treated cotton fibers only released little combustible volatile during the thermal pyrolysis process. The cone calorimetry results showed that the heat release rate (HRR) and the total heat release (THR) of treated cottons were much lower than those of control cottons. The bending length increased 44.8% for the cotton fabric treated with 30% ACMPEP. The scanning electron microscopy (SEM) and the X-ray diffraction suggested that the finishing process only slightly affected the cotton fiber structure. The FTIR spectroscopy analysis confirmed the cross-linking reaction between ACMPEP molecules and cellulose. The tensile strengths of the finished cotton fabrics decreased a little. Together, the results suggested that the ACMPEP-treated cotton fabrics have excellent flame retardance and durability. (C) 2019 Elsevier Ltd. All rights reserved.