Investigations of thermoplastic poly(imide-urethanes) flame-retarded by hydroxyl-terminated poly(dimethylsiloxane)

Author: A series of novel intrinsically flame-retardant thermoplastic poly(imide-urethanes) (TPIUs) has been synthesized by 4,4′-diphenylmethane diisocyanate (MDI), poly(tetrahydrofuran) (PTMG), pyromellitic anhydride (PMDA), and hydroxyl-terminated poly(dimethylsiloxane) (PDMS) used as flame retardants. The obtained TPIU/PDMS exhibited good tensile strength and elongation at break. TPIU/PDMS has a higher thermal decomposition temperature than that of commercial PTMG-MDI-1,4-butanediol-based thermoplastic polyurethane (TPU) according to thermal gravimetric analysis. The total heat released and peak heat release rate of TPIU/12.4%PDMS were found to be lower than those of the pure TPIU by 8.0% and 26.3%, respectively, based on cone calorimeter testing. The condensed phase of TPIU/PDMS has been investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy. The results indicate that the good flame retardancy of TPIU/PDMS can be attributed to thermally stable compounds with Si-O structures on the surface of its char layers.