• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.354-358
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• 1998

The effect of thermal conditions on the clustering of sulfonated polystyrene ionomers was investigated. It was found that when the zinc-sulfonated ionomer was dried above a matrix glass transition temperature (Tg), the cluster Tg was observed at ca. 310 ℃, which is ca. 45 ℃ higher than that for the ionomer dried below the matrix Tg. This difference is believed to be the result of the increase in chain mobility at higher temperatures, which improves the multiplet formation and clustering; thus the cluster Tg increases. In the lithium ionomer case, however, the increase in the cluster Tg was ca. 6 ℃ upon annealing. From the results, it was suggested that in the zinc ionomer, the zinc ion is soft and divalent, which results in weaker interactions in multiplets, and thus decreases the stability of the multiplets. Therefore, the thermal effect is more significant for the zinc ionomers than for the lithium ionomers.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.424-424
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• 2009

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.106-110
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• 2001

Formation of stoichiometric lithium-, nickel-, and zinc- ferrites by calcining organo-metallic precursors a temperature below 40$0^{\circ}C$ is examined using DTA/TG, and XRD techniques. It attempts to simulate th immobilization of metal ions in industrial liquid influents (waste) through the synthesis of stoichiometric spinel ferrites (SSF). Two steps of the SSF formation during thermal treatments are noted. The transformation of magnetite to ${\gamma}$ - Fe$_2$O$_3$and subsequent first formation of SSF were observed at temperatures ranging from 200 to 45$0^{\circ}C$. Th formation of cation-containing ${\gamma}$-Fe$_2$O$_3$and subsequent second formation of the ferrite occurred at temperature ranges of < 45$0^{\circ}C$ and 500 to $650^{\circ}C$, depending on the heating rate used. Then the temperature range of 200t 45$0^{\circ}C$ is critical to the performance of the technique, because a calcination at the range would lead to a complete formation of SSF, avoiding the occurrences of ${\gamma}$-Fe$_2$O$_3$and ion-containing ${\gamma}$-Fe$_2$O$_3$. If not, so $\alpha$-Fe$_2$O$_3$would occur. And annealing at temperature above $650^{\circ}C$ must be employed by which solid-state reactio of $\alpha$-Fe$_2$O$_3$with metal ions (possibly metal oxides) to form SSF can be conducted.