Dynamic mechanical study of thermoplastic polyurethane/polypropylene blends

Abstract

Thermoplastic polyurethanes (TPU) are an important class of elastomers that found many novel and specialized applications where high mechanical and chemical performances are prerequisites. They are known for their good mechanical strength, wear and tear resistance, and low-temperature elasticity. The aim of this work is to study the viscoelastic behaviour of TPU, polypropylene (PP) and their blends using dynamic mechanical analysis. Blends of TPU+PP as well as samples of pure TPU and PP were prepared using a laboratory twin-screw extruder. Primary and secondary viscoelastic functions were determined. Primary viscoelastic functions, viz. storage modulus, loss modulus and loss tangent, were evaluated in the temperature range -100 to 250°C. The secondary viscoelastic functions creep, recovery and creep modulus were investigated in the creep-fatigue regime at 25 - 65°C. A master curve at the reference temperature 25°C for the creep modulus of TPU, PP and TPU+PP blends was created by applying the time-temperature correspondence principle. The obtained results are discussed.