The development of poly (propylene glycol) (PPG) polyether polyols with low unsaturation has attracted recent attention to partially or fully replace poly (tetramethylene ether glycols) (PTMEG) in coatings, adhesives, sealants, elastomers (CASE) and thermoplastic polyurethanes (TPUs). The loss of material performance in conventional PPG-based polyurethanes for CASE and TPU applications compared to PTMEG-based systems is well established and is attributed to a lack of strain-induced crystallization in soft segments comprised of PPG, and the presence of unsaturation at chain ends in conventional PPG polyols, leading to reduced network formation. VORANOL™ 223-060LM, from Dow, is a newly developed polyether polyol that delivers liquid processing at room temperature, low unsaturation and optimized extent of microphase separation from conventional urethane hard segment chemistries. The performance of VORANOL 223-060LM has been benchmarked against that of PTMEG- and alternative PPG-based polyether polyols in cast elastomers and TPUs with respect to reactivity, tensile properties, hysteresis, dynamic mechanical spectroscopy (DMS) and elevated temperature compression set. Cast elastomers and TPUs based on VORANOL 223-060LM polyol were observed to deliver material performance comparable to PTMEG-based systems and comparable to or exceeding alternative PPG-based polyether polyols.
Cast elastomers were prepared from quasi-prepolymers synthesized at 60 °C (2 h) using ISONATE™ 125M/143L and benzoyl chloride (stability). The prepolymer was combined with a curative comprised of 1, 4-butanediol, polyol, and catalyst (1.05 index), cast into a heated, open mold at 80-90 °C, de-molded in <5 min, and subsequently post-cured at 80 °C for 16 h.