The Influencing Factors Of Rubber Low Temperrature Performance

With the popularization of polar scientific research and oil exploitation in alpine regions,the performance of rubber in low temperature environment has attracted more and more attention.However,there are few reports on systematically exploring the influencing factors of low temperature performance of rubbers with different molecular structures.Therefore,natural rubber(NR),nitrile butadiene rubber(NBR),ethylene propylene diene monomer(EPDM),ethylene-vinyl acetate rubber(EVM)and vinyl acetate rubber(AVM)with significant differences in polarity and saturation were selected as the research objects.Differential scanning calorimeter(measuring glass transition temperature Tg),retraction temperature tester(measuring low temperature retraction temperature TR10)and low temperature brittleness tester(measuring brittleness temperature Tb)were used as low temperature performance characterization methods.The effects of crosslinking density,carbon black filling amount,particle size and fillers on the low temperature performance of rubber with different molecular structures were investigated,in order to provide scientific reference for the study of low temperature performance of rubber materials and the application of rubber products in low temperature environment.Firstly,the effect of crosslinking density on the low temperature properties of NR,NBR,EPDM and EVM was studied.The results showed that crosslinking density had no effect on Tg,TR10 and Tb of NR,NBR,EPDM and EVM.The Tb of EPDM with different crosslinking density is much lower than its Tg,which has lower low temperature brittleness.Secondly,the effects of carbon black filling amount and particle size on the low temperature properties of NR,NBR,EPDM and ACM were studied.The results showed that the filling amount and particle size of carbon black had a significant effect on the low temperature properties Tg and Tb of polar NBR.The filling of 70 phr carbon black N550 and 30 phr carbon black N234 could improve the low temperature brittleness of NBR.The Tb of EPDM filled with carbon black is under-70 °C and far lower than its Tg,and the low temperature brittleness is the lowest.The change of carbon black filling amount and particle size has no effect on the low temperature performance of non-polar rubber.The influence of carbon black filling amount and carbon black particle size on the low temperature performance of saturated and unsaturated rubber is consistent.Finally,the effects of different kinds of fillers such as carbon nanotubes(CNTs),carbon nano-onions(CNOs),carbon microspheres(CMSs)and silica aerogel(SA)on the low temperature properties of NR and NBR were studied.The results showed that the filler type had a great influence on the Tg and Tb of the polar unsaturated rubber NBR.Under the filling of CNTs and SA,the low temperature brittleness of NBR was significantly improved.In conclusion,the carbon black content,particle size and filler type have the most significant effect on the low temperature performance of polar unsaturated rubber NBR.Under different influencing factors,there are many trends in the brittleness temperature of each rubber;the Tb of EPDM and its carbon black filled materials with different crosslinking densities is much lower than its Tg,and the low temperature brittleness is the lowest.