• Elastomers and Composites
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• v.49 no.1
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• pp.13-23
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• 2014

In this work, glycolide, L-lactide and ${\varepsilon}$-caprolactone monomers were polymerized into the triblock copolymers by two step polymerization method and their non-isothermal crystallization behaviors were studied by combination of modified Avrami and Ozawa formula for further analysis of their behaviors. The result showed that PGCLA21 gave the highest value for supercooling analysis and super cooling degree increased with L-lactide content. Crystallization velocity constant, however, showed no significant change. The result of cooling function in specific relative crystallization degree showed that the increase of L-lactide content made an effect on the more enhancement of crystallization velocity of the PGCLA than PGCL. The result of big logF(T) value with the L-lactide content above critical point for PGCLA41 and PGCLA21 showed that bigger cooling velocity needed to gain same crystal size compared with PGCL. This means that it gives negative effect in the increase of crystallization velocity.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.608-614
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• 2009

In this work, ruthenium substituted SBA-15's(Ru-SBA15's) of various Si/Ru ratios were prepared using a non-ionic triblock copolymer surfactant, $EO_{20}PO_{70}EO_{20}$, as template. We investigated the nitrogen or oxygen adsorption/desorption behaviors of the Ru-SBA-15's for their future applications as catalysts or selective adsorbents, etc. The pore size of the Ru-SBA-15's was determined by both the Barrett-Joyner-Halenda(BJH)($D_{BJH}$) and the Broekhoff-de Boer analysis with a Frenkel-Halsey-Hill isotherm(BdB-FFF) method($D_{BdB-FHH}$). The $D_{BJH}$ and $D_{BdB-FHH}$ of the Ru-SBA-15 having 50/1 ratio of Si/Ru were 3.9 nm and 4.7 nm, respectively. The transmission electron microscope(TEM) image of the Ru-SBA 15 of the Si/Ru mole ratio of 50 showed that the pore size is 4.7 nm, which is consistent with the $N_2$ adsorption results with the BdB-FHH method. The surface area of pores form oxygen adsorption/desorption isotherm was higher than that from the nitrogen adsorption/desorption isotherm by the Brunauer-Emmett-Teller(BET) method, which were respectively $612.7m^2/g$, and $573.3m^2/g$. X-ray diffraction(XRD) patterns and TEM analyses showed that the mesoporous materials possess well-ordered hexagonal arrays.