Enhancement of physical properties of thermoplastic polyurethanes by blending with cyclic olefin copolymer elastomer

Abstract In this study, two different thermoplastic polyurethanes (TPUs), a poly(ester)‐based TPU including aromatic diisocyanate units (TPU1) and a poly(ester‐ether)‐based TPU including aliphatic diisocyanate units (TPU2) were blended with a cyclic olefin copolymer (COC) elastomer to prepare TPU‐rich blend films via melt compounding in a twin screw extruder equipped with a slit die and film casting rollers. Morphological features and viscoelastic properties of blend films were characterized with scanning electron microscope analysis, different test protocols in melt rheology measurements, and dynamic mechanical analyzer tests, in detail. Viscoelastic properties of blend films were quantified with various mathematical approaches such as Williamson model, discrete retardation spectrum (DRS), Burger, and Findley equation. It was found that COC phase dispersed more homogenously into TPU1 matrix than TPU2. COC elastomer addition significantly increased the melt viscosity and melt elasticity of TPUs and improved the creep strength. Highlights COC addition enhanced the viscosity and elasticity of TPUs in melt state. The creep strains of TPUs decreased by 65% with addition of 40 wt% of COC.