SUMMARY:This paper reviews several types of thermoplastic polyurethane elastomers, and the unique properties these polymers have. I n discussing the hydrolysis stability of thermoplastic polyurethane elastomers the suitability of these polymers for such study was pointed out. A relationship between poly(ester-urethane) composition in terms of methylene group concentration, hardness and chain stiffness, and hydrolysis stability was shown. The dominant role of polyurethane acid number in thermoplastic poly(est,er-urethane) hydrolysis stability was demonstrated and the origin of this unexpected acid number was discussed. The pronounced stabilizing action of added poly(carbodiimide) in thermoplastic poly(ester-urethane) hydrolysis was shown, as well as the severe destabilizing act.ion of a carboxylic acid, stearic acid. The hydrolysis st,abilities of thermoplastic poly(ester-urethane) elastomers based on poly(s-caprolactone) glycol and on poly(hexamethy1ene carbonate) glycol were also described. ZUSAMMENFASSUNG :Die Hydrolysestabilitat einiger thermoplastischer Poly(ester-urethan)-Elastomerer in Abhangigkeit vom molekularen Aufbau wird untersucht. Entscheidend fur den hydrolytischen Abbau dieser Polymeren ist das Auftreten von Carboxylgruppen. Es werden Moglichkeiten aufgezeigt, diesen Abbau zu verringern, $3 z . B. durch Zusatz von Poly(carbodiimiden). AbschlieBend werden die Hydrolyaestabilitat von thermoplastischen Poly(ester-urethan)-Elastomeren untersucht, die Poly-( E Caprolacton) und Poly(hexamethy1encarbonat) als Glykolkomponente enthalten.

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This paper reviews several types of thermoplastic polyurethane elastomers, and the unique properties these polymers have. In discussing the hydrolysis stability of thermoplastic polyurethane elastomers the suitability of these polymers for such study was pointed out. A relationship between poly(ester‐urethane) composition in terms of methylene group concentration, hardness and chain stiffness, and hydrolysis stability was shown. The dominant role of polyurethane acid number in thermoplastic poly(ester‐urethane) hydrolysis stability was demonstrated and the origin of this unexpected acid number was discussed. The pronounced stabilizing action of added poly(carbodiimide) in thermoplastic poly(ester‐urethane) hydrolysis was shown, as well as the severe destabilizing action of a carboxylic acid, stearic acid. The hydrolysis stabilities of thermoplastic poly(ester‐urethane) elastomers based on poly(ϵ‐caprolactone) glycol and on poly(hexamethylene carbonate) glycol were also described.

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Many of the outstanding physical properties that characterize elastomeric Polyurethans have been realized in a soluble, thermoplastic variety, Polyurethan VC, which displays the superficial properties of a rubbery vulcanizate at room temperature and so is considered to be virtually crosslinked. High tensile strength as well as good tear, abrasion, solvent, oil, and ozone resistance characterizes this polymer. Since these properties are realized in the unvulcanized state, many useful applications of the readily processable polymer can be made, avoiding the complications which attend the use of conventional (vulcanizing) urethan elastomers. Outdoor exposure and indoor accelerated weathering studies demonstrated a deficiency in the weather resistance of the raw polymer. Weather-induced changes, believed to be due to ultraviolet-initiated autoxidation, have been estimated by noting changes in the stress-strain properties as well as the ultraviolet and infrared absorption spectra of the polymer on exposure to natural and artificial weather conditions. The beneficial effects of certain carbon blacks, conventional antioxidants, and ultraviolet absorbers on the weather resistance of the polymer have been described.