Hyperspectral Raman Line Imaging of Syndiotactic Polystyrene Crystallinity

Abstract

The crystallinity of syndiotactic polystyrene (sPS) is studied by hyperspectral Raman line imaging. Images of a 140 × 1200 μm region of an sPS test piece containing 39 200 pixels/image were generated from spectra taken over the wavenumber interval between 300 and 875 cm⁻¹. The spectral region includes the moderate-intensity crystallinity-sensitive bands in the 770 800 cm⁻¹ region, as well as other useful but weaker marker bands. Factor analysis was used to extract structure information from the set of spectra. Four non-noise factors were extracted; two were assigned to crystalline and amorphous sPS and the other two to background. Score images of the crystalline and amorphous sPS factors were used to visualize distribution of those species. The results were compared to the integrated Raman intensity image for the 773 cm⁻¹ band of crystalline sPS.