The molecular structures,molecular weights,viscocities and moduli of thermal aged and thermal oxidative aged epoxidized natural rubber（ENR） were determined by means of FTIR,GPC and RPA.It was found that the decrease in the IR absorption intensity of the epoxy was more obvious than that of the C[ZJLX,Y]C bond,and the molecular weight and the dynamic rheological behavior had changed.Mn and Mw were reduced respectively by 26% and 5% after thermal oxidative aging.After thermal aging,however,Mn was reduced by 2% only,and Mw increased by 6%.The molecular weight distribution broadened from 3.18 for ENR to 3.43 for the thermal aged ENR and 4.05 for the thermal oxidative aged ENR.The decrement of η* of the thermal aged ENR with rising shear rate was larger than that of the unaged ENR,but for the thermal oxidative ENR the decrement of η* was lower compared with the unaged ENR.G′ of the thermal aged ENR decreased slightly and G′ of the thermal oxidative aged ENR was obvious lower than that of the unaged ENR in the low frequency range.In the high frequency range,G′ of the thermal aged ENR was larger than that of the unaged ENR,and G′ of the thermal oxidative ENR increased to the same level as that of the unaged ENR.
