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

An investigation on the effect of strain on the domain structure of thermoplastic polyurethane elastomers (TPEs) is reported. Thermal characterization utilizing differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) is presented along with mechanical properties of model TPEs before, and after, varying degrees of strain aging. Model TPEs were subjected to tensile strains between 100 and 400% elongation and aged for varying lengths of time at ambient and elevated temperatures. DSC and DMA were utilized to investigate the changes in morphology that occurred as a result of strain elongation. The effect of strain aging on the TPEs mechanical properties such as abrasion resistance is also discussed. DSC results indicated that the polymer undergoes morphology changes due to strain, resulting in some degree of phase mixing. DMA data indicated that polyester TPEs and polyether TPEs respond differently to induced strain, suggesting that domain reordering in these materials may occur by different mechanisms. (C) 1998 Elsevier Science B.V. All rights reserved.