Synthesis and characterization of lignin-HTPB copolyurethane

Lignin-HTPB copolyurethanes have been synthesized from hydroxyl terminated polybutadiene (HTPB) and varied quantities of lignin and toluene diisocyana te. Iii spectroscopy and estimation of isocyanate groups have established t he formation of HTPB polyurethane and lignin-HTPB copolyurethane. The cross link density, sol fraction, diffusion coefficient, mechanical properties an d X-ray crystallinity of lignin-HTPB copolyurethane have been measured and compared with those of HTPB polyurethane. Tensile strength improvement of l ignin-HTPB copolyurethane was observed up to 3-wt.% lignin incorporation. H igh hydroxyl value of lignin has been found responsible for the decrease in tensile strength with the increase in lignin content of lignin-HTPB copoly urethane. (C) 2001 Elsevier Science Ltd. All rights reserved.