Abstract
Lignin based copolymers were synthesized using a single pot, solvent free, melt condensation reaction. The synthesis occurred in two stages. In the first stage a prepolymer consisting of a diol and diacid with varying amounts diamine was heated under vacuum. In the second stage, prepolymer was mixed with kraft lignin and further reacted under vacuum at elevated temperature. Progression of polymerization was monitored using FT-IR and ESI-MS. Polymer properties were characterized using DMA, DSC and TGA techniques. The morphology was analyzed using polarized optical microscopy. Polymer mechanical properties were found to be influenced by the type of diacid, lignin and diamine content, ball milling of lignin and presence of an acid catalyst. The lignin-copolymers were shown to have thermoplastic behavior. Additionally, above 30 wt% lignin the lignin-copolymers did not exhibit melt behavior.