Improving the Fire Performance of Nylon 6,6 Fabric by Chemical Grafting with Acrylamide

Our previous study has demonstrated that photografting can enhance the flame retardancy of both polyamide and polyester fabric. In this work, efforts to use chemical grafting with acrylamide (AM) as the monomer and dibenzoyl peroxide (BPO) as the initiator were made to improve the homogeneity of the grafting chains and the flame retardancy of nylon 6,6 fabric. The effects of reaction time, reaction temperature, and monomer concentration on the percentage of grafting (PG) were investigated. The effect of PG on the fire performance of AM-g-nylon 6,6 fabric was also studied. The flame retardancy and thermal behavior were characterized in terms of the limiting oxygen index (LOI), UL 94 test, cone calorimetry, thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The results showed that the after-flame time and char length were significantly reduced after grafting. The heat release rate (HRR) of grafted sample was decreased by 28% compared to that of the ungrafted sample. The optimal grafting conditions were obtained as follows: reaction time, 1.5 h; reaction temperature, 70 °C; and concentration of total monomer, 15 wt %. The chemical structure and microstructure of AM-g-nylon 6,6 fabric were analyzed by attenuated-total-reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. A possible grafting mechanism is proposed and discussed.