Thermal properties and hydrogen bonding in polymer blend of polybenzoxazine/poly(N-vinyl-2-pyrrolidone)

The thermal properties and hydrogen bonding behavior of B-a type polybenzoxazine (PBZZ)/PVP blends were investigated by DSC and FTIR. The DSC result shows a single Tg over the entire compositions and a large positive deviation based on Kwei equation was observed in the Tg versus composition diagram, implying that strong hydrogen bonding interaction exists between PBZZ and PVP segments. The strength of hydrogen bonding interaction is in the order of inter-association between the hydroxyl group of PBZZ and the carbonyl group of PVP (KA=594 L mol−1)>self-association between the hydroxyl group of pure PBZZ (KB=72.6 L mol−1)>inter-association between the hydroxyl and the Mannich-based bridge of pure PBZZ (KC<10 L mol−1). Good correlation between DSC and FTIR analysis were observed.