Investigation of novel polyurethane elastomeric networks based on polybutadiene-ol/polypropyleneoxide mixture and their structure–properties relationship

Polyurethane elastomer networks were designed and 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. Our observations 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) and chemical network (crosslinking) have synergistic effects. Moreover, Flory–Hugins interaction parameters of soft and hard segments were calculated. Synthesized polyurethane elastomer networks have a structure similar to semi interpenetrating polymer networks, which is named pseudo-semi-IPN. These novel polyurethane elastomer networks show higher tensile strength and economic benefit than polyurethanes which are based on other non-polar polyols.

Research highlights
► Design and synthesis of novel semi-IPN based on PPO and HTPB.
► Finding optimum composition of PPO/HTPB to obtain best mechanical properties.
► HTPB/PPO polyurethane networks with higher tensile strength their related polyurethanes.
► Improvement of thermal stability of PPO or HTPB-based polyurethanes.
► Evaluation of chemical & physical aspects on properties of semi-PU IPNs simultaneously.