Petroleum Engineering

Biography

Biography: Bum Jae Lee

Abstract

Conventional polyolefin-based thermoplastic elastomers have a variety of merit. But the copolymers including block, graft and blend types have some limitations due to their low use temperature. In this study, novel polyolefin-g-poly(t-butylstyrene) as one of the promising high utility temperature polyolefin-based thermoplastic elastomers was synthesized by the graft anionic living polymerization from the initiation of styrene unit form the poly(t-butylstyrene) hard grafts along the poly(ethylene-ter-1-hexane-ter-divinylbenzene) backbone as the soft block (0.3~0.5 mol% of graft sites). Phase-separation occurred in these polyolefin TPEs when the Mn of poly(t-butylstyrene) was more than 5,000 g/mol, which was evidenced by the presence of two distinct Tgs(-20°C of polyolefin soft block and 125°C of poly(t-butylstyrene) hard block) observed in DSC and DMTA. These high temperature polyolefin TEPs exhibited distinct mechanical property with high modulus and toughness even above 125°C. And when the content of P(t-butylstyrene) over 28wt%, excellent mechanical properties: high tensile strength (>21MPa) with high elongation (>1,100%) could be obtained, similar to that of S-EB-S(30wt% styrene content). The multi-carboxyl functionalized polyolefin-g-poly (t-butylstyrene) could be synthesized by the incorporation of high vinyl oligo-isoprene at the end of poly (t-butylstyrene) hard block via sequential anionic polymerization followed by the thiolene click reaction with thioglycolic acid to incorporate multi-carboxyl groups at the pendant vinyl units. The contact angle of these result multi-carboxyl functionalized polyolefin (12-COOH/molecule) was decreased to 58° compared to 95° in case of the non-functionalized polyolefin TPEs.