Wrinkles and Cracks -- Quantifying the Mechanical Properties of Polymer Thin Films

ORAL

Abstract

To further engineer materials that are mechanically strong and fracture-resistant, direct knowledge of the key mechanical properties such as stiffness, strength, and ductility is a necessity. Previous works have demonstrated the capabilities of a combined wrinkling-cracking test to measure the elastic modulus of ultrathin glassy polymer films. It is shown that the modulus observed often deviate significantly from the bulk, and may undergo subcritical cracking from continuous loading conditions. In this study, the elastic and fracture properties of polycarbonate thin films is measured as a function of film thickness and strain rate. Additionally, using the crack density and channel crack growth, in combination with our numerical model, the strain energy release rate 𝒢 can be calculated to benchmark the failure criterion of the material in terms of a crack driving force that is independent of sample history and geometry.

*This work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).

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Presenters

  • Shawn Chen

    • Materials Science & Engineering Department, Northwestern University

Authors

  • Shawn Chen

    • Materials Science & Engineering Department, Northwestern University

  • Caleb Fishell

    • Materials Science and Engineering Division, National Institute of Standards and Technology

  • Jae-Hwang Lee

    • Mechanical and Industrial Engineering, University of Massachusetts Amherst
    • Mechanical and Industrial Engineering, University of Massachusetts
    • Department of Mechanical and Industrial Engineering, Univ of Mass - Amherst

  • Christopher Soles

    • Materials Science and Engineering Division, National Institute of Standards and Technology
    • NIST -Natl Inst of Stds & Tech
    • Materials Science & Engineering Division, National Institute of Standards & Technology
    • National Institute of Standards and Technology

  • Edwin Chan

    • National Institute of Standards and Technology
    • Materials Science and Engineering Division, National Institute of Standards and Technology
    • NIST -Natl Inst of Stds & Tech

  • Kenneth Shull

    • Materials Science & Engineering Department, Northwestern University
    • Materials Science and Engineering, Northwestern Univ