Construction of anti-flame network structures in cotton fabrics with pentaerythritol phosphate urea salt and nano SiO2

Based on pentaerythritol phosphate urea salt (PEPAS), 2-(4-(4,6-dichloro- 1,3,5-triazin-2-ylamino) phenylsulfonyl) ethyl sulfate sodium (CYPA) and nano-SiO2, a novel flame-retardant method for cotton fabrics was developed via chemical modification and nano deposition technologies. The chemical structure of PEPAS and CYPA was studied using Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR, H-1) spectroscopy. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) combined with elemental dispersive spectroscopy (EDS) and FT-IR were performed on the cotton fabrics, showing that PEPAS, CYPA and nano SiO2 were successfully introduced into the cotton fabrics, formed a complex internal network structure and generated a continuous carbon layer during the burning process. TG/DTA analysis indicated that the sample treated with 300 g/L PEPAS, 125 g/L CYPA and nano-SiO2 deposition (TCFSi) showed significantly smaller exothermic quantities than the original cotton sample (OCF) and the char yield data were improved from 3.41% in OCF to 15.02% in TCFSi at 700 degrees C. The LOI value of the TCFSi sample reached 31.8 and remained at 27.8 after 20 launderings, while that of OCF was only 17.8. In the vertical flammability tests, the TCFSi samples were hard to ignite, had excellent self-extinguishing ability and exhibited no after-flame and afterglow time while the OCF samples burnt to complete ash with an after-flame time and afterglow time of 17.4 s and 42.6 s, respectively. Even after 50 launderings, the afterglow time of the TCFSi sample was only 3.1 s and the basic form of the fabric was sustained after combustion. Overall, the results showed that the anti-flame performance of the cotton fabrics treated with PEPAS, CYPA and nano SiO2 was significantly enhanced.