Effect of treatment‐varying generation number of with hyperbranched polyphosphate ammonium salts on the fire retardant finish performance of cotton fabric

In this study, the aim was to study the effect of the generation number on flame resistant properties of treated fabric. A series of hyperbranched poly phosphate ammonium salts (HBPOPNs) with various generation numbers was successfully prepared by modifying different generations of hydroxyl-terminated hyperbranched polymers (HBPs). The chemical structure of the samples was investigated by Fourier transform infrared spectroscopy, which revealed the presence of a P–O–C covalent bond between cellulose and HBPOPN. The thermal decomposition behavior of the samples was characterized by thermogravimetric analysis. With increasing of generation number (2, 3 and 4), the residues were 31.4%, 33.1%, and 34.8%, respectively, which indicated that the thermal stability of HBPOPN-treated fabric improved with higher generation number. In the vertical flammability test, all samples treated with the different generations of HBPOPN were immediately extinguished after removing the igniter. Values of the limit oxygen index of 42.0, 42.7 and 43.0 were observed with the increase in the generation number (2, 3 and 4) at a concentration of 160 g/L. After 50 laundering cycles (LCs), the LOI values were still remained at 29.3, 29.7 and 29.6. With increasing of generation number, the peak heat release rate and the total heat release of the treated sample decreased slightly. Hyperbranched polymers from the 2nd to the 4th generation could be applied to cotton fabric with excellent flame retardant properties and durability.