Thermal processability of polyvinyl alcohol / polyvinyl pyrrolidone blends

Polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) blends were difficult to be thermal processed due to their special structure and properties. In this paper, by adopting molecular complexation and plasticization, PVA/PVP blends were prepared through thermal processing. By means of DSC, TGA, FTIR and high pressure capillary rheometer, the intermolecular interactions, thermal behavior and rheological property of the blends were studied. The results show that PVP can form hydrogen bonding with PVA and modifiers, thus increased the hydrogen bonding types of the systems, and further shielded the hydroxyl groups in PVA molecular chains and retarded their dehydroxylation, resulting in increase of the initial decomposition temperature, which is beneficial to the thermal processing of PVA. With increase of the PVP content, the melting temperature of the systems slightly increases and then decreases, obtaining the thermal processing window of 86.4°C; both the apparent viscosity and the shear sensitivity of the melt increase first and then decrease after the mass fraction of PVP reaches 20%; and the flow activation energy is reduced, indicating the improvement of the stability of the thermal processing of PVA. The addition of proper PVP, i.e. 10%, can increase the crystallinity of PVA, thus obtained the highest tensile strength, i.e. 43MPa.