Flame-resistant polymeric composite fibers based on nanocoating flame retardant: thermogravimetric study and production of α-Al2O3 nanoparticles by flame combustion

In this work, we investigated the effect of aluminum chloride hexahydrate as a flame retardant coating on the flammability of cellulosic and polyester (polyethylene terephthalate, PET) fibers. The samples were characterized by several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, vertical flammability test, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and differential thermogravimetric (DTG). Aluminum chloride hexahydrate <100 nm in size has been found to form continuous and dispersed particles coatings on the fibers surface which shows efficient flame retardant properties. The optimum loadings to impart flame retardant properties were about 8.73-9.93% for cellulosic fiber and 20.30-23.48% for polyester fiber. Flame retardant activity was tested by a vertical flammability tester and LOI. XRD results of ashes revealed that after combustion of the treated specimens, the existence of alpha-Al2O3 nanoparticles was detected in the ashes of treated samples. TGA/DTG of pure, treated fibers and the salt was accomplished, and thermograms were compared and discussed. The results obtained are in favor of the free radical theory and also the dust or wall effect theory.