Raman spectra of the a-, p, 7-and smectic polymorphs of isotactic polypropylene were recorded at 298 and 16.5 K. At 298 K the spectra of the polymorphs were very similar except in the antisymmetric C-H stretching region. However, at 16 K the Raman spectra of the polymorphs show different features in several wavenumber shift regions. Comparisons are made with infrared spectra recorded at 298 and 100 K and interpretations are made on the basis of nonequivalent sites in the monoclinic unit cells.

No abstract

No abstract

No abstract

The technique of diffuse reflectance infrared spectroscopy can be used to characterize materials without recourse to extensive sample preparation. The applicability of this sampling approach is demonstrated on a variety of diffusely scattering solids including bulk powders and foams. The technique is also applied to the identification of chromatographically (HPLC and TLC) separated fractions.