The effects of varying the backbone polyol on the properties of polyurethane elastomers were investigated. Unaged polyester urethanes, especially those based on polyethylene and polybutylene adipates (mol wt 2000), were generally tougher but considerably less resistant to hydrolysis than polyurethanes prepared from polyethers of similar molecular weights. Low molecular weight polyols (650 to 1260) led to more highly crosslinked elastomers with improved tensile strength, modulus, hardness, but with reduced flexibility. Elastomers based on hydroxyl-terminated polybutadiene urethanes and to a lesser extent polyoxybutylene glycol urethanes (mol wt 1300), showed the best resistance to hydrolysis at 80 C, while those based on polydiethylene adipate (mol wt 1000) and polyoxypropylene glycol (mol wt 1250) showed the best resistance to petrol (STF) at 65 C. (Author)
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