Formation and Thermal Behavior of Polystyrene and Polystyrene/Clay Gels

DSC was used to study the thermal behavior of virgin PS as well as of PS/clay nanocomposites of exfoliated brush and of intercalated structure dissolved in carbon disulfide. Compared to virgin PS, the behavior of the brush material did not show any obvious difference, whereas the intercalated material demonstrated markedly larger heats of gelation and gel melting. Isoconversional kinetic analysis of the melting process revealed that the activation energy was independent of the conversion for the gels prepared under isothermal conditions, whereas an increase in the activation energy with the extent of conversion was observed for the gels prepared under continuous cooling conditions. The melting of the nonisothermally prepared gels apparently occurred alongside with the formation of new gel structures.