Effect of hydrolysis time on molar mass, glass transition temperature, crystallinity, and resistance to thermooxidation at elevated temperatures was analyzed for Estanes 54600, 54610, and 54650. Kinetics of the hydrolysis can be plausibly described in terms of the first-order reaction with an average induction period of about 7 days. Reduction of molar mass induced by hydrolysis brings about an appreciable decrease in glass transition temperature, fraction of crystalline domains of soft segments, and thermooxidative stability. The latter effect is manifested by shortening of the lifetimes (related to 5% mass loss) the temperature dependence of which obeys the Arrhenius plot. The observed differences in hydrolysis resistance of Estanes can be related to their chemical composition. © 1994 Wiley Heyden Ltd, Chichester and Akadémiai Kiadó.
Effect of Hydrolysis on molar mass and thermal properties of poly(ester-urethanes)
Pegoretti, Alessandro;Penati, Amabile
1994-01-01
Abstract
Effect of hydrolysis time on molar mass, glass transition temperature, crystallinity, and resistance to thermooxidation at elevated temperatures was analyzed for Estanes 54600, 54610, and 54650. Kinetics of the hydrolysis can be plausibly described in terms of the first-order reaction with an average induction period of about 7 days. Reduction of molar mass induced by hydrolysis brings about an appreciable decrease in glass transition temperature, fraction of crystalline domains of soft segments, and thermooxidative stability. The latter effect is manifested by shortening of the lifetimes (related to 5% mass loss) the temperature dependence of which obeys the Arrhenius plot. The observed differences in hydrolysis resistance of Estanes can be related to their chemical composition. © 1994 Wiley Heyden Ltd, Chichester and Akadémiai Kiadó.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione
