Hydrolytic and thermal stability of novel polyurethane elastomers

Abstract

AbstractNovel Polyester glycols with alkyl side groups were used for the improvement of thermal stability and hydrolytic stability of polyester urethane elastomers. The novel polyester glycols used are poly( β ‐methyl‐ δ ‐valerolactone)glycol (PMVL), poly(3‐methyl pentamethylene adipate) glycol (PMPA), poly(nonamethylene‐co‐2‐methyl octamcthylene carbonate) gycol (PNCO). A mixture of PNCO and poly(dimethyl siloxane)gycol (PNCO/PDMS) was also used. Polyurethane network elastomers were prepared from 4,4′‐diphenylmethane diisocyanate (or 2,4‐tolylene diisocyanate), and a mixture of 1,4‐butane diol and trimethylol propane by a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. Morphology were also measured by means of polarizing microscopy, dynamic viscoelastometer, and ESR. The properties of novel polyurethane elastomers have good mechanical properties comparable to those of the general purpose polyester urethanes, and better thermal and hydrolytic stability than PTMG‐based polyurethane. These polyurethane elastomers were exposed in out door during 2 year in Nagasaki, JAPAN. The novel polyurethane clastomers held alomost constant values for gel fraction, swelling ratio, relative modulus during 12 months, while poly(oxytetramethylene oxide)‐based polyurethane as a control decreased the these values. Relationship of degradation behaviors with chemical structure and morphology were discussed.