Flame retardant effect of 1-aminoethyl-3-methylimidazolium hexafluorophosphate in thermoplastic polyurethane elastomer

Abstract

In this paper, 1-aminoethyl-3-methylimidazolium hexafluorophosphate ([APMIm]PF6) and 1-butyl-3-methylimidazolium hexafluorophosphate ([EMIM]PF6) were used as flame retardant additives in thermoplastic polyurethane elastomer (TPU). The flame retardant effect of [APMIm]PF6 and [EMIM]PF6 in TPU had been investigated by cone calorimeter (CCT), scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), microcombustion calorimeter (MCC), fourier transform infrared spectroscopy (FT-IR), smoke density test (SDT), thermogravimetric analysis (TG) and thermogravimetric/fourier transform infared spectroscopy (TG-IR), respectively. The results indicated that TPU/[APMIm]PF6 had better thermal properties compared with pure TPU and TPU/[EMIM]PF6. The peak heat release rate (pHRR) of TPU/A-1.0 was remarkably reduced by 32.97% and 19.15%, in comparison with that of TPU and TPU/E-1.0. Moreover, the total heat release (THR) and smoke production rate (SPR) of TPU/A-1.0 were the lowest among all samples. And, in the early stage of fire, [APMIm]PF6 can promote the formation of protective carbon layer, reduce the HRR and SPR. Therefore, it is necessary to develop environment-friendly green flame retardants.