Local and segmental dynamics in modified polystyrene containing chlorine and bromine atoms
Egorov V. M.1, Ryzhov V. A.1
1Ioffe Institute, St. Petersburg, Russia
Email: victor_egorov1@inbox.ru
The specific heat capacity of polystyrene and its modifications obtained by substitution of hydrogen atoms in the benzene ring with methyl groups and chlorine and bromine atoms has been measured by differential scanning calorimetry (DSC). The studied temperature range was 300-520 K. The glass transition temperature is found to depend on the character of the substitutions. The frequency shift and change in amplitude of the librational band vibrations have been measured by long-wavelength infrared spectroscopy. A correlation between changes in the activation energy of segmental motion and potential librational barriers is established. The influence of substitutions on the cooperative nature of segmental motion in case of devitrification of the studied polymers is discussed. The excess conformational entropy in polymers below the glass transition temperature is estimated. Keywords: molecular dynamics, heat capacity, IR spectra, polystyrene and its modifications.
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