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...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.展开更多
The gel and sol parts in epoxidized natural rubber(ENR) were separated with toluene and 2-pentanone, respectively, and their thermal aging behaviour were studied by FTIR spectrometry. The results indicate that the car...The gel and sol parts in epoxidized natural rubber(ENR) were separated with toluene and 2-pentanone, respectively, and their thermal aging behaviour were studied by FTIR spectrometry. The results indicate that the carbon-carbon double bonds and the epoxy bonds in both gel and sol are destroyed successively on aging process, accompanied with the occurance of the hydroxyl, ether, carbonyl of aldehyde and ketone groups. Along with prolonging the aging time, the aldehyde and ketone are further converted into ester structures. These changes of the functional groups demonstrate the gel is less thermostable than sol in ENR.展开更多
The thermogravimetric analysis of ENR(epoxidized natural rubber) has been carried out byTG-DTG methods at temperature rising rate of 5, 10, 15 and 20 ℃ · rmin-1. The results showed thatthe activation energy of t...The thermogravimetric analysis of ENR(epoxidized natural rubber) has been carried out byTG-DTG methods at temperature rising rate of 5, 10, 15 and 20 ℃ · rmin-1. The results showed thatthe activation energy of the thermoreaction in flowing air during the course of mass loss wasn＇t alwayskeep rising, but declined at mass loss of 1.0％～10.0％, 20.0％～30.0％ and 70. 0％～80. 0％.展开更多
文摘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.
文摘The gel and sol parts in epoxidized natural rubber(ENR) were separated with toluene and 2-pentanone, respectively, and their thermal aging behaviour were studied by FTIR spectrometry. The results indicate that the carbon-carbon double bonds and the epoxy bonds in both gel and sol are destroyed successively on aging process, accompanied with the occurance of the hydroxyl, ether, carbonyl of aldehyde and ketone groups. Along with prolonging the aging time, the aldehyde and ketone are further converted into ester structures. These changes of the functional groups demonstrate the gel is less thermostable than sol in ENR.
文摘The thermogravimetric analysis of ENR(epoxidized natural rubber) has been carried out byTG-DTG methods at temperature rising rate of 5, 10, 15 and 20 ℃ · rmin-1. The results showed thatthe activation energy of the thermoreaction in flowing air during the course of mass loss wasn＇t alwayskeep rising, but declined at mass loss of 1.0％～10.0％, 20.0％～30.0％ and 70. 0％～80. 0％.
