Investigation of the Mechanical Properties of TPU on Molecular and Micro Scale

Abstract

The mechanical properties of thermoplastic polyurethane (TPU) are highly dependent on the chemical composition [1]. This dependency was investigated with micromechanics based and molecular dynamics simulations. TPU is a copolymer which consists of hard and soft segments. The microstructure of the copolymer for different mass fractions of the hard segment was determined with the group contribution method [2] and the phase diagram according to [3]. The results are compared with the microstructures obtained with the Self Consistent Field Theory [4]. For the assessment of the Young’s moduli of the segments tensile tests on the molecular level were performed. Furthermore, a sensitivity study of several parameters which have an influence on the results of the molecular dynamics simulations was performed. With the information about the Young’s moduli and the microstructure micromechanics based simulations were performed to determine the Young’s modulus of the TPU. The outcome of this research study is a complete workflow for the determination of the elastic properties of multiphase materials based on the molecular structure of the phases using molecular dynamics and micromechanics simulations. Multiphase ma- terials, so called digital materials, can be manufactured for example with the polyjet 3D-printing technology. Thus, a future application of the developed methodology is the investigation of the elastic properties of 3D-printed digital materials.