Dynamic Viscoelasticity of PUF under Small Strain and Prediction of Dynamic Viscoelasticity in a Wide Frequency Range

ABSTRACTThe dynamic viscoelasticity of polyurethane fiber (PUF) under small strain was studied with dynamic mechanical analysis and differential scanning calorimetry, and its viscoelasticity was predicted in a wide frequency range. The results revealed that the loss factor (tan δ) was about 0.05 and the phase angle (δ) was 2.86°, very close to the δ of a perfect elastomer in the range from −100°C to −80°C. The master curves superimposed by time‐temperature superposition (TTS), the frequency range of the storage modulus master curve spanned 17 orders of magnitude from 10−7 Hz to 1010 Hz, and the loss modulus master curve spanned 13 orders of magnitude from 10−3 Hz to 1010 Hz. The apparent activation energy of the soft segment relaxation decreased with increasing temperature in the range from −70 to −26°C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47070.