An infrared spectroscopy study of PES PVP blend and PES-g-PVP copolymer

Systematic study of FTIR spectra was carried out on the PES/PVP blends and PES-g-PVP copolymers . In the blends, no shift of carbonyl group absorbance was observed. In the copolymers, there was an occurrence of blue-shift that increases with the grafting degree, which can be used as a compelling evidence of PVP being grafted onto PES . This phenomenon was interpreted from the stereo-hindrance effect. Besides, as the intensity of carbonyl group absorbance increased proportionally with the degree of grafting obtained by elementary analysis, FTIR, a simple and easy tool, became feasible for the quantitative determination of PVP content in the graft copolymers . Calibration curves with high correlation coefficient were established from which the quantitative relationship between the intensity of carbonyl group absorbance normalized by a chosen internal reference and the grafting degree can be obtained.