Strain effects on thermal transitions and mechanical properties of thermoplastic polyurethane elastomers

An investigation on the effect of strain on the domain structure of thermop lastic polyurethane elastomers (TPEs) is reported. Thermal characterization utilizing differential scanning calorimetry (DSC) and dynamic mechanical a nalysis (DMA) is presented along with mechanical properties of model TPEs b efore, and after, varying degrees of strain aging. Model TPEs were subjecte d to tensile strains between 100 and 400% elongation and aged for varying l engths of time at ambient and elevated temperatures. DSC and DMA were utili zed to investigate the changes in morphology that occurred as a result of s train elongation. The effect of strain aging on the TPEs mechanical propert ies such as abrasion resistance is also discussed. DSC results indicated th at the polymer undergoes morphology changes due to strain, resulting in som e degree of phase mixing. DMA data indicated that polyester TPEs and polyet her TPEs respond differently to induced strain, suggesting that domain reor dering in these materials may occur by different mechanisms. (C) 1998 Elsev ier Science B.V. All rights reserved.