Preparation of halogen-free functionalized cyclophosphazenes-based flame retarding cotton fabric via a simple UV-curing method

Cotton fabric is a flammable material, which can quickly cause civilian deaths and property losses during fire emergencies. It is, therefore, of particular interest to develop flame-retardant cotton fabric to meet the safety standards of households and industries. For this purpose, a novel UV-curable flame-retardant finishing, based on functionalized cyclophosphazenes (CCPD) and 2-hydroxyethyl methacrylate phosphate (HMP), is prepared and applied to cotton fabric (to form cotton fabric/CCPD–HMP composite). Subsequently, this presence of CCPD–HMP on the finished cotton fabric surface is confirmed using scanning electron microscopy and thermogravimetric analysis. Additionally, compared to the pristine cotton fabric, an increase in the residual char yield from 16.73 to 37.44 wt% and the limiting oxygen index from 18.5 to 24.5 vol% is indicated for the fabric/CCPD–HMP composite. Moreover, the after-flame time and after-glow time of the cotton fabric/CCPD–HMP composite reduces from 26.1 to 0 s and 60 to 0.5 s in vertical flame tests, respectively. Meanwhile, the cone calorimeter tests show that the total heat release, the peak heat release, and the fire growth rate index of the cotton fabric/CCPD–HMP composite reduce by 11.6%, 38.37%, and 30%, respectively. It is anticipated that the novel flame-retardant finishing and the UV-curing method reported in this study will provide a new research direction for flame-retardant cotton fabric.