A novel phosphorus-containing flame retardant for the formaldehyde-free treatment of cotton fabrics

A novel flame retardant, poly (1,2-dicarboxyl ethylene spirocyclic pentaerythritol bisphosphonate) (PEPBP) has been synthesized by the reaction of spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) with tartaric acid (TA). PEPBP was used as the flame-retardant finishing agent for cotton fabrics. The flame retardancy of the samples was characterized by limiting oxygen index (LOI) and the vertical burning test. The cotton fabric sample with 21.2 wt% of PEPBP has a LOI value of 33.8, which is 14.4 higher than that of the untreated cotton sample. The treated cotton fabrics have shorter after-glow time, shorter char length and no after-flame during the vertical burning test. The thermal decomposition behaviors of the fabrics, the chemical structures and morphologies of the residues of the fabrics were investigated using thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM), respectively, and a possible flame retardant mechanism was discussed.