Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure ...Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.展开更多
The relationship between the reduced viscosity and concentation of sulfonated styrene-isoprene- styrene triblock copolymer（SSIS） and its ionomers in toluene and toluene/methanol solutions were studied. The intrinsic...The relationship between the reduced viscosity and concentation of sulfonated styrene-isoprene- styrene triblock copolymer（SSIS） and its ionomers in toluene and toluene/methanol solutions were studied. The intrinsic viscosity \ was calculated. The results show that SSIS tends to form an intra-molecular chain interaction and form more enclosed molecular chain with a lower reduced viscosity and intrinsic viscosity when the sulfonation degree x（SO3H） decreased. A change of interaction from intra- to inter-molecular chain was observed, and the intrinsic viscosity improved from 0.641 dL/g to 0.656 dL/g by increasing the sulfonation degree from 3.95% to 7.36% due to the chain combination. This also make the size of molecular chain of SSIS larger than SIS . Although be a precipitant for SIS , a few amounts of methanol can change the solubility of SSIS in toluene by destroying the combination of molecular chain. Lanthanum ionomers showed a lower reduced viscosity as compared with sodium and zinc ionomers.展开更多
文摘Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.
文摘The relationship between the reduced viscosity and concentation of sulfonated styrene-isoprene- styrene triblock copolymer（SSIS） and its ionomers in toluene and toluene/methanol solutions were studied. The intrinsic viscosity \ was calculated. The results show that SSIS tends to form an intra-molecular chain interaction and form more enclosed molecular chain with a lower reduced viscosity and intrinsic viscosity when the sulfonation degree x（SO3H） decreased. A change of interaction from intra- to inter-molecular chain was observed, and the intrinsic viscosity improved from 0.641 dL/g to 0.656 dL/g by increasing the sulfonation degree from 3.95% to 7.36% due to the chain combination. This also make the size of molecular chain of SSIS larger than SIS . Although be a precipitant for SIS , a few amounts of methanol can change the solubility of SSIS in toluene by destroying the combination of molecular chain. Lanthanum ionomers showed a lower reduced viscosity as compared with sodium and zinc ionomers.
