Effect of methylene chain length of polycarbonate (PC) glycols on properties of PC-based polyurethanes

Polycarbonate-based polyurethane elastomers (PUEs) were prepared from poly(carbonate) glycol baring the number of methylene unit of 3, 4, 5 and 6. Aggregation structure and mechanical properties of these PUEs were investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and tensile testing. The difference in temperature of the glass transition temperature of polyols (ΔT_g,polyols) and T_g,PUEs (ΔT_g) decreased with decreasing methylene chain length indicating the degree of microphase separation become stronger with decreasing methylene chain length. Also, Young's modulus increased with decreasing methylene chain length. Around the higher strain region in the stress-strain curve, the elongation-induced crystallization was suppressed for the PC-glycol-based polyurethane with even number of methylene chain length.