Preparation of a flame-retardant coating based on solvent-free synthesis with high efficiency and durability on cotton fabric.

A novel formaldehyde-free and halogen-free flame retardant (FR), HBPOPN, was synthesized under solvent-free conditions and applied on cotton fabric to improve its durability. The reactive groups of HBPOPN could react with cellulose to form covalent bonds. The limit oxygen index (LOI) value of 160 g/L HBPOPN-treated cotton was 42.0 % and the LOI value was still 29.3 % after 50 laundering cycles (LCs). The entire vertical flammability test showed no after-flame or after-glow time. Moreover, the cone calorimetry results suggested that the peak heat release rate (PHRR) and the total heat release (THR) of the HBPOPN-treated samples were dramatically lower than those of the untreated samples. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns indicated that HBPOPN hardly affected the structure of cellulose. Thermogravimetric data from thermogravimetric analysis (TGA) with an infrared spectrometer implied that HBPOPN changed the thermal decomposition mechanism of cotton. The mechanical properties of the treated cotton fabrics were well maintained. These results indicate that the HBPOPN-treated samples had highly efficient flame retardancy and superior durability.