ABSTRACT The melting behavior of o-dichlorobenzene in isotactic polypropylene (iPP) / o-dichlorobenzene gel was investigated as functions of incubated time and gelation temperature. When the 5 wt% gel was incubated at 0oC, DSC measurement showed that the melting peak of o-dichlorobenzene was first close to that of pure o-dichlorobenzene, and then gradually changed to the peak along with the high temperature shoulder with increasing incubated time. In addition the melting enthalpy increased up to 2 days and reached a constant value. These results indicated that the o-dichlorobenzene was gradually bound in the network structure even after the gel was formed. Polarizing microscopic measurements showed that the spherulites were first isolated each other, and gradually contacted with adjacent ones. It was suggested that the morphology of iPP chain allowed the bound state of solvent change. When the gelation temperature was changed, the spherulites formed in iPP gel became larger with increasing gelation temperature from 0oC to 70oC. The melting behavior of o-dichlorobenzene in the 30 wt% gel was characterized by two endothermic peaks. The high melting peak provided almost the same temperature irrespective to gelation temperature, but the low melting peak decreased at higher gelation temperature. Since the gelation is regarded as crystallization in solution, the large spherulites were formed at high gelation temperature. These spherulites would be filled by lamellar due to secondary crystallization. This allows the non-crystalline domain smaller. As a result the melting temperature would be lowered.
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