期刊
JOURNAL OF PHYSICAL CHEMISTRY B
卷 111, 期 44, 页码 12685-12692出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp0759168
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Degradation and relaxation studies have been performed on two polystyrene (PS)-montmorillonite clay nanocomposites, one of which has an intercalated PS-clay structure and the other an exfoliated PS-clay brush structure. Compared to virgin PS, both nanostructured materials have demonstrated the following similarities: (a) a high yield of a-methylstyrene in the degradation products as measured by infrared spectroscopy; (b) larger values of the activation energy of the thermal degradation as determined by isoconversional kinetic analysis of thermogravimetric data; and (c) larger values of the activation energy for the glass transition as found from the frequency dependence of the glass transition temperature measured by multifrequency temperature-modulated differential scanning calorimetry. These effects are taken as structure independent manifestations of nanoconfinement of the PS chains in the PS-clay materials. Heat capacity measurements have been employed to evaluate the size of the cooperatively rearranging region, V-CRR, that is found to be structure dependent. Compared to its value in virgin PS, V-CRR has markedly increased in the exfoliated PS-clay brush system but remained practically, unchanged in the intercalated PS-clay system.
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