FTIR study of poly(propylene carbonate)/bisphenol A blends

A systematic investigation by FTIR spectroscopy was undertaken on blends of poly(propylene carbonate) (PPC and bisphenol A (BPA). It provided direct evidence of the hydrogen bond (H-bond) between BPA O-H groups and PPC C=O groups. Using a curve-fitting method, qualitative as well as quantitative information concerning this H-bond interaction was obtained. The inter-H-bond in PPC/BPA blends was weaker than the self-H-bond in BPA. The absorptivities of the free and the H-bonded C=O groups were nearly equal. The fraction of H-bonded C=O in the blends increased with BPA content and leveled off at a value close to 40 %. Finally, FTIR-temperature measurements of pure PPC and a representative blend were reported: by monitoring the peak areas of C=O absorptions, the dissociation of the inter-H-bonds and the thermal degradation of PPC were observed. It revealed that the presence of BPA clearly retarded the thermal degradation of PPC.