Design And Preparation Of Special Isoprene-based Elastomers

In this paper,isoprene-based elastomers were designed and prepared based on two special application fields of low temperature resistance and plasticization.Low temperature resistant polyisoprene elastomers,butadiene-pentadiene copolymer elastomers and liquid polyisoprene elastomers for plasticizers were prepared respectively.Polyisoprene elastomers(RPI)with cis-1,4,trans-1,4,1,2 and 3,4 structures were synthesized by free radical emulsion polymerization.Crystallization properties of RPI at low temperature were tested by volume dilatometer and compared with that of NR.The random structure of RPI inhibits the crystallization behavior at low temperature,and no crystallization was observed in the tests at-20℃,-25℃ and-30℃ The molecular weight of RPI is low,the sulfurization process is not obvious,and the mechanical properties are poor.Polyisoprene elastomers(SPIP)with cis-1,4,trans-1,4,3,4 structures and random butadiene-isoprene copolymer elastomers(SPIBP)with different butadiene content were synthesized by anionic solution polymerization.Crystallization properties of SPIP and SPIBP at low temperature were tested by volume dilatometer and compared with BR,NR and high cis-polyisoprene rubber,respectively.The random structure inhibits the crystallization behavior of SPIP and SPIBP at low temperature,and no crystallization occurs at-25℃ and-40℃ for a short time.A small amount of crystallization is observed in the long-term test at-25oC.SPIP vulcanizate has high tensile strength and low 300%elongation stress.The tensile strength of SPIBP vulcanizate is lower than that of SPIP,and the 300%elongation stress is higher than that of SPIP.Liquid polyisoprene rubber(LIR)of different molecular weights were prepared by RAFT polymerization.The plasticization of LIR was carried out with SBR1502/BR9000 and SSBR2466/CB24 rubber composites as the matrix,and compared with the aromatic oil plasticizer.The plasticizing effect of LIR is comparable to that of aromatic oil plasticizers and gradually decreases as the molecular weight of LIR increases.LIR is significantly superior to aromatic oil plasticizers in terms of migration resistance,extraction resistance and thermal stability due to its ability to participate in co-vulcanization reactions.