POLYURETHANE ELASTOMERS BASED ON MOLECULAR-WEIGHT ADVANCED POLY(ETHYLENE ETHER CARBONATE) DIOLS .2. EFFECTS OF VARIATIONS IN HARD SEGMENT CONCENTRATION

A series of polyurethane elastomers were studied in which the soft segment composition was a molecular weight advanced poly(ethylene ether carbonate)diol (2025 mol wt) and the hard segment composition was based on MDI/1,4‐butanediol. These polyurethane elastomers had a constant soft segment composition and block length, a constant hard segment composition, but a variable hard segment block length and concentration (31.9–65.2 wt % hard segment). Properties such as rubbery plateau modulus, solvent resistance, melting point, hardness, tensile strength, and hard segment run length all improve with increasing hard segment concentration. DMA and DSC data indicate a partially phase mixed morphology. However, phase mixing must occur at domain boundaries since the soft segment Tg is nearly invariant with hard segment concentration. Annealing studies indicate that the optimum post‐cure temperature, for 1 h, is about 175°C. Copyright © 1990 John Wiley & Sons, Inc.