| 초록 |
In this study, the physical gelation of triblock copolymer Polystyrene- b-(ethylene-co-butylene)-b-styrene in different hydrocarbon oils with different concentrations was investigated. Thermoplastic elastomer gels were prepared by dissolving the poly (styrene-ethylene-butylene-poly) styrene triblock copolymer in the presence of hydrocarbon oil at different concentrations. The linear viscoelastic behavior, thermal transitions, swelling behavior and gel properties on physical gelation were discussed. The linear viscoelastic behavior was highly dependent on the copolymer concentration and type of oils. The degree of moduli responses of triblock copolymer gels increased with higher gelation melting temperature, thereby indicating the longer lifetime of gel junctions. Small amount of aromatic content in the hydrocarbon oil decreases the thermal stability of micelle formation of the gel and increases the compatibility of the solvent with copolymer, thereby resulting in low gelation melting temperature, lower moduli, as well as gel strength. With increase in the paraffinic content and molecular weight of the hydrocarbon oil, the gelation melting temperature, moduli and gel properties showed improvement. The DSC results showed phase separation of soft segment and hard segment. The Tg of soft EB midblock was not dependent on the triblock copolymer concentration nor the type of oils, whereas the Tg of hard segment styrene endblock was highly dependent on triblock copolymer concentration and type of oils. It should be noted that although the polystyrene block is responsible for the gel junctions and the length of copolymer block, and thereby determining the ease of gelation and thermal stability of the gels formed, however this study proved that the molecular weight and paraffinic hydrocarbon contents of oil have also contributed to the stability of micelles and the incompatibility of hydrocarbon oil in triblock copolymer. |
