Effect of aging under strain on the physical properties of polyester–urethane elastomer

Abstract

The mechanical, degradation, and related thermal properties of segmented polyester-urethane elastomers which were aged under strain in three different environments (25ŶC in air, 85ŶC in air, and 85ŶC in water) were investigated by stress舑strain measurements, DSC, and FTIR. From the stress舑strain measurements, it showed that the polyester-urethane samples aged under a high prestrain, particularly at high temperature, resulted in decreases of the initial slope, and stress and elongation at break. The behavior of stress舑strain curves also showed that aging the polyester-urethane at a higher prestrain and a higher temperature leaded the urethane elastomer to be more brittle. Morphological changes which were induced in the segmented elastomer by aging under strain were investigated by DSC in terms of the glass transition temperature of the soft segments, the melting temperature of the hard segments, and the heat of fusion of the crystalline hard segments. FTIR measurements indicated the degradation of the ester C舑O舑C bond during aging at high strain, especially in the water. Based on the DSC and FTIR studies, the behavior of the stress舑strain measurements of the aged urethane elastomers was explained. © 1994, The Society of Polymer Science, Japan. All rights reserved.