Preparation And Properties Of Epoxidized Polyisoprene Polymerized With Rare Earth Catalyst System

At present the production growth of natural rubber (NR) is slow, difficult to meet the needs of domestic development of rubber.The molecular structure and physical performance of cis-1,4-polyisoprene rubber are most close to natural rubber, so it can instead of natural rubber to solve the shortage problem of natural rubber resources.This paper studies the Russian Ln-IR, through in situ generated peroxide formic acid to prepare EIR,reaction conditions and the structure of EIR performance were studied. Aims to provide theoretical basis for practical production.The epoxidation of rare earth isoprene(Ln-IR) rubber was investigated by using hydrogen peroxide and organic performic acid as epoxide agent and catalytic agent respectively. The structure of epoxidized Ln-IR was characterized by1H-NMR and IR. The results showed that when reaction temperature was40℃-60℃, the reaction time was2h-5h, the mole ratio of formic acid and hydrogen peroxide was about1, the epoxidation could occur without side reaction and the high epoxy degree of Ln-IR can be obtained.The properties of compounds and vulcanizates for five grades of rare earth isoprene(Ln-IR) rubbers were studied. The results showed that the scorch time of EIR compounds reduced, curing rate and maximum torque value increased as the extent of epoxidation of EIR increased from0to50%. The optimum post curing condition was obtained:145℃/10min. With the increasing extent of epoxidation, the maximum stress, tensile strength and hardness increased, the breaking elonqation ratio decreased. After heat-aging at100℃for48h, the maximum stress, tensile strength and breaking elongation ratio decreased, and there is a obvious performance degradation as the extent of epoxidation increased. The oil resistance properties of EIR improved as the extent of epoxidation increased, and it was clearly better than the resistance properties of Ln-IR, it means epoxy modification can improve the oil resistance property of Ln-IR. The hardness of vulcanzite increased after air-oven aging and it decreased after oiling. So the hardness of vulcanizate can be adjusted by heat-aging and oiling.