Lignin-based polymer blends: analysis of intermolecular interactions in lignin-synthetic polymer blends

The development of lignin-based thermoplastics relies on altering the viscoelastic properties of lignin through chemical modification or polymer blending. In polymer blends, miscibility is dependent on the occurrence of exothermic reactions such as hydrogen-bonding, acid-base interactions and the like. The effects of polymer-polymer interactions, specifically hydrogen-bonding, on lignin-based thermoplastics was studied in a series of lignin/synthetic polymer blends prepared by melt extrusion. Thermal analysis revealed miscible blend behavior in the lignin blends containing PEO and PET, whereas the PVA and PP lignin blends appeared immiscible. The glass transition (T-g) of the lignin/PEO and lignin/PET blends showed a negative deviation from a linear mixing rule, indicative of specific intermolecular interactions. DRFT-IR analysis revealed the formation of a strong intermolecular hydrogen bond between lignin and PEO, but not with PET. (C) 2003 Elsevier Ltd. All rights reserved.