Characterization of Polymer Interface by Micro Raman Spectroscopy

Micro Raman spectroscopy was applied to characterize the interface region of multi-layered film specimens in which ethylene-propylene random copolymer(EPR) was sandwiched with polyethylene(PE) or polypropylene(PP) sheets. Micro Raman line scan of the interface region for PE/EPR pair indicated that PE molecules migrated into the EPR phase and crystallized there, forming a mixed phase where the PE crystallites were embedded in EPR matrix. Apparent diffusion constant(D) evaluated from the thickening rate of the mixed phase strongly depended on the chemical composition of EPR, i.e., D increased with increasing the ethylene content of EPR. On the contrary, the mixed phase thickness of PP/EPR pair showed the opposite dependence on the composition of EPR.