5 years ago

Atomistic Simulation of a Thermoplastic Polyurethane and Micromechanical Modeling

Atomistic Simulation of a Thermoplastic Polyurethane and Micromechanical Modeling
Gregory C. Rutledge, Pieter J. in ‘t Veld, Nikolaos Lempesis
Thermoplastic polyurethanes constitute a versatile family of materials with a broad variety of engineering applications. However, connection between their chemical structure and mechanical properties remains elusive, in large part due to their heterogeneous nature, arising from segregation of chemically distinct segments into separate domains, with resulting complex morphologies. Using atomistic simulations, we examine the structure and mechanical properties of a common family of thermoplastic polyurethanes (TPU) comprising 4,4′-diphenylmethane diisocyanate and n-butanediol (hard segment) and poly(tetramethylene oxide) (soft segment). A lamellar stack model previously developed for the study of semicrystalline polymers is applied here for the first time to a phase-segregated copolymer. Equilibrium structure and properties were evaluated for TPUs with different ratios of hard and soft components, using a combination of Monte Carlo and molecular dynamics simulations. Stress–strain behaviors were then evaluated using nonequilibrium molecular dynamics (NEMD) simulations. The compositional dependence of the Young’s moduli thus obtained is shown to be well-approximated by a micromechanical homogenization model of the hard and soft components. Voigt (upper) and Reuss (lower) bounds of modulus were obtained for orientationally averaged aggregates and shown to be greater than those measured experimentally. The discrepancy is explained in terms of the strain rate dependence of elastic moduli, characterized by an Eyring-like function.

Publisher URL: http://dx.doi.org/10.1021/acs.macromol.7b01296

DOI: 10.1021/acs.macromol.7b01296

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.