m amrollahi - Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box ۱۵۸۷۵/۴۴۱۳, Tehran, Iran
g mir mohamad sadeghi - Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, P.O. Box ۱۵۸۷۵/۴۴۱۳, Tehran, Iran

Polyurethane elastomer networks were synthesized based on hydroxyl terminated polybutadiene/polypropyleneoxide (HTPB/PPO) mixtures, 2,4-toluene diisocyanate and 1,4- butanediol. Various networks with different molar ratio of HTPB to PPO (0/100, 25/75, 50/50, 75/25 and 100/0) had been prepared. Depending on the length of soft segment, average functionality of polyol mixtures, mechanical and thermal properties of samples were varied. Ourobservations confirmed that final properties of the networks can be attributed to two synergistic factors: (a) formation of chemical network (crosslinking) and (b) soft segment length. An optimum composition was found. This optimum composition shows that both physical (hard domains) andchemical network (crosslinking) have synergistic effects. Synthesized polyurethane elastomer networks have a structure similar to semi interpenetrating polymer networks, which is namedpseudo-semi-IPN. These novel polyurethane elastomer networks show higher tensile strength and economic benefit than polyurethanes which are based on other non-polar polyols.

Synthesis, Polyurethane Elastomer, Psedue-Semi IPN, Microstructure, Mechanical and Thermal Properties