Effects of Chain Orientation on Raman and Brillouin Scattering Spectral of Hydrostatically Extruded Polypropylene.
UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY
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Raman and Brillouin scattering techniques have been used to study the effect of chain orientation in uniaxially extruded isotactic polypropylene. The orientation parameters P2 and P4 are obtained by measuring several Raman scattering intensities associated with the CH2 rocking mode at 841cm. Both P2 and P4 parameters represent the average of the local orientational distribution of the polypropylene backbone. The Raman scattering result for P2 is found in good agreement with the previous study using another vibrational band. The high frequency elastic constants C11, C33, C44 and C13 of extruded isotactic polypropylene are determined by Brillouin scattering. The elastic constants of deformed polymers have been related to the orientation parameters determined by Brillouin scattering. The result obtained for P2 at high extension using Brillouin scattering is found to be smaller than that of Raman. The result suggests that the pair orientation correlation between segments is important in affecting the hypersonic velocity. Author
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