Characterization of blends of poly(vinyl chloride) and poly(N-vinyl pyrrolidone) by FTIR and13C CP/MAS NMR spectroscopy

Blends of poly(vinyl chloride) (PVC) with Poly(N-vinyl pyrrolidone) (PVP) were investigated by Fourier infrared spectroscopy (FTIR) and high-resolution solid-state 13C cross-polarization/magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) spectroscopy. The intermolecular interactions between PVP and PVC are weaker than the self-association of PVP and the inclusion of the miscible PVC results in the decreased self-association of PVP chains, which was evidenced by the observation of high-frequency shift of amide stretching vibration bands of PVP with inclusion of PVC. This result was further substantiated by the study of 13C CP/MAS spectra, in which the chemical shift of carbonyl resonance of PVP was observed to shift to a high field with inclusion of PVC, indicating that the magnetic shielding of the carbonyl carbon nucleus is increased. The proton spin-lattice relaxation time in the laboratory frame (T1 (H)) and the proton spin-lattice relaxation time in the rotating frame (T1ρ(H)) were measured as a function of the blend composition to give the information about phase structure. It is concluded that the PVC and PVP chains are intimately mixed on the scale of 20–30Å.