Improvement of the low-temperature property of aliphatic polycarbonate glycols-based polyurethane elastomers

Structure-property relationship of polyurethane elastomers (PUEs) based on aliphatic carbonate glycols (PCglycols) with various molecular weights (HO-[(CH₂)_mOC(=O)O]n-(CH₂)_m-OH, m = 3 and 6, M_n = 1000-3000) were investigated to improve their low-temperature property. Differential scanning calorimetry (DSC) measurement revealed that the glass transition temperature (T_g) of the soft segment in the PUEs decreased ca. 10-25 ^oC and crystallized hard segment exhibited larger heat of fusion with increasing molecular weight of the PC-glycol. This trend clearly implies that the degree of microphase separation of the PUEs became stronger with an increase in molecular weight of the PC-glycol. In the tensile testing, Young's modulus and tensile strength increased with increase in the degree of microphase separation. In other words, an increase in molecular weight of the PC-glycol gives the PUEs bearing lower T_g and superior mechanical properties.