Thermal strain recovery of anelastic monodomain liquid crystalline networks: Mechanically induced strains ratios

Authors

  • Wanting Ren,

    1. School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332 0295, USA
    2. R&D Center, China Textile Academy, YanJingLi Middle Street, Beijing 100025, P.R. China
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  • Whitney M. Kline,

    1. School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332 0295, USA
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  • Philip J. McMullan,

    1. School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332 0295, USA
    2. Department of Chemistry, Grambling State University, Grambling, LA 71245, USA
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  • Anselm C. Griffin

    Corresponding author
    1. School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, GA 30332 0295, USA
    • Phone: +1 404 894 2490, Fax: +1 404 894 8780
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Abstract

A series of smectic liquid crystalline network polymers was subjected to a large uniaxial stress at temperatures far below the clearing temperature. Their dimensional recovery is anelastic showing substantial retained strain. This process produced a temporally stable monodomain state. Upon heating this monodomain from room temperature, recovery of the original film dimensions occurs. The strain recovery (length) curves show a pronounced curvature as the temperature approaches the smectic–isotropic temperature. It is proposed that nanosegregation of netpoints in the smectic structure is responsible for the anelasticity and that the temperature dependence of the shape recovery is consistent with a balance between enthalpic and entropic forces with temperature. An interesting mechanically induced strains ratio (MISR) was observed on heating these pre-stressed films. Loss of the monodomain structure near the isotropization temperature is postulated to rationalize the shape of the MISR curves.

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