Flame Retardancy Of Thermoplastic Polyurethane Elastomer Based On Fumaric Acid (Salt)

Thermoplastic polyurethane elastomer(TPU)is a polymer copolymerized by isocyanate and polyol,which is an elastic material between rubber and plastic.TPU has good prospects in many fields because of its superior performance,such as high wear resistance,high strength and high elasticity.However,TPU is flammable and it can release a lot of heat and smoke during combustion,which limits its application in some fields.Therefore,it is very important to improve the flame retardancy of TPU.Considering the shortcomings of traditional flame retardants such as,low efficiency and environmental pollution,the development of halogen-free,high efficiency and low addition of new flame retardants has become the main trend.In view of the above problems,flame retardant TPU composites were prepared by using fumaric acid(FA),ferrous fumarate(FF),monosodium fumarate(MF)and FA/ammonium polyphosphate(APP)as flame retardants in this paper.The combustion parameters including ignition,heat release rate,smoke factor and luminous flux of TPU composites were carried out using LOI,cone calorimeter test(CCT)and smoke density tester(SDT).And the thermogravimetric infrared spectroscopy(TG-IR)technique was used to test the flame retardancy of TPU composites based on fumaric acid(salts).In TPU/FA system,CCT test showed that compared with pure TPU,the peak heat release rate(pHRR),peak smoke release rate(pSPR)and smoke factor(SF)of samples with 2.0 wt%fumaric acid were reduced by 50.8%,59.2%and 75.2%respectively.TG results show that FA effectively reduced the thermal decomposition rate of TPU system and increased the quality of residual carbon residue.TG-IR results showed that the TPU composites containing FA released non-flammable gases such as water vapour and carbon dioxide at lower temperature during thermal decomposition,and reduced the release of toxic gases.In TPU/FF system,CCT test showed that compared with pure TPU,the pSPR and SF of sample TPU4 with 2.0 wt%FF decreased by 66.7%and 80.4%respectively,which played better smoke suppression effect.TG results showed that the residual carbon content of TPU 4 was 14.7%,which was 40.8%higher than that of pure TPU.In TPU/MF system,CCT test showed that compared with pure TPU,the pHRR of MF-4(2.0 wt%)decreased by 63.9%,total smoke release(TSR)decreased by 46.7%,and SF decreased by73.3%.TG-IR results showed that TPU containing MF could dehydrate into carbon at lower temperature,which could delay the decomposition process of TPU.In TPU/APP/FA system,CCT test showed that the pHRR of TPU/APP/FA-0.5 added with 0.5wt%FA and 1.5wt%APP was 205.0kW/m~2,which was deceased by 29.5%compared with TPU/APP.SDT results showed that the luminous flux of TPU/APP/FA-0.5 was 24.5%,which was 18.9%higher than that of TPU/APP.The data showed that using FA as synergist of APP could further improve the flame retardancy of TPU,and both of them have certain synergistic flame retardancy.