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Journal of Polymer Science Part B: Polymer Physics, Vol.32, No.7, 1137-1147, 1994
Photon-Correlation Spectroscopy of Syndiotactic Poly(N-Butyl Methacrylate) Near the Glass-Transition
Slow relaxing longitudinal density fluctuations in bulk syndiotactic poly(n-butyl methacrylate) [PBMA] were studied by photon correlation spectroscopy as a function of temperature from 70 to 90-degrees-C. The shape of the light-scattering relaxation function broadened as the temperature approached the glass transition (T(g) = 55-degrees-C). The average relaxation time shifted with temperature, consistent with previous studies of PBMA. The relaxation functions were analyzed in terms of a distribution of relaxation rates. The calculated distribution was clearly bimodal and the shape altered with temperature. The higher frequency peak in the distribution corresponds well with previous mechanical and dielectric relaxation studies of the intramolecular relaxation of the acrylate ester side chain. The resolution of the distribution into two modes is due to a well-defined side-chain motion with relaxation strength comparable to the primary glass-rubber relaxation.
Keywords:RAYLEIGH-BRILLOUIN SPECTROSCOPY;POLY(NORMAL-BUTYL METHACRYLATE);LIGHT-SCATTERING;RELAXATION