Study On The Flame Retardant Properties Of Thermoplastic Polyurethane Elastomer With Aluminum Hypophosphite And Its Composite System

As a petroleum-based polymer material,thermoplastic polyurethane elastomer(TPU)is easily ignited in the air and produces a large amount of droplets and smoke during the combustion process.Its flammability greatly limits its application.In this paper,the inorganic phosphorus flame retardant aluminum hypophosphite(AHP)and the organic phosphorus flame retardant diethyl aluminum hypophosphite(AlPi)are used to improve the flame retardancy of the TPU and compared.The synergistic effects of sepiolite(SEP)and modified sepiolite ZIF-8@SEP as a synergist with AHP for flame-retardant TPU were also studied.In addition,the flame-retardant properties,mechanical properties and processing properties of TPU composites are also explored.The main research results are as follows:1.The structure and thermal stability of AlPi and AHP and their influence on TPU performance were compared.AlPi had better thermal stability than AHP,but AHP had better flame retardancy on TPU.which The LOI was increased from 21.9%to 26.4%when 12wt%AlPi was added in TPU composites.However,it produced many droplets and ignited absorbent cotton,which can only reached UL-94 V-2.The LOI of the TPU composites was increased from 21.9%to 26.0%when added 12wt%AHP,the droplets produced were decreased and the rating of UL-94 about V-0 was reached.The addition of 12wt%flame retardants including AlPi and AHP respectively had no significant effect on the melt index of TPU,and it caused little deterioration of the mechanical properties of TPU.2.SEP and AHP were compounded to improve the fire performance of TPU composites.SEP and AHP were added to TPU in different proportions.The study found that SEP and AHP havd a good synergistic effect.With the addition of 9.0wt%AHP and 1.0wt%SEP,the flame retardancy of the TPU composites had been significantly improved,and its LOI was increased from 21.9%to 26.7%,and the rating of UL-94 about V-0 was also passed.The addition of SEP reduced the melt index of the TPU composites,however,it improved the mechanical properties of the TPU composites.3.Z1F-8@SEP was obtained by modifying the surface of SEP using ZIF-8.Then,ZIF-8@SEP and AHP were compounded into TPU composites.The study found that ZIF-8@SEP and AHP had a synergistic effect.With the addition of 8.0wt%AHP and 1.0wt%ZIF-8@SEP,the flame retardancy of the TPU composites had been significantly improved,the LOI was increased from 21.9%to 27.5%,and the UL-94 V-0 rating was also passed.The addition of ZIF8@SEP further reduced the emission of smoke and toxic gases,and improved the processing and mechanical properties of TPU composites.