Effects of heat exposure and volumetric compression on Poisson's ratios, Young's moduli and polymeric composition during thermo-mechanical conversion of auxetic open cell polyurethane foam

DUNCAN, Oliver, CLEGG, Francis, ESSA, Abdusalam, BELL, Anthony, FOSTER, Leon, ALLEN, Tom and ALDERSON, Andrew (2019). Effects of heat exposure and volumetric compression on Poisson's ratios, Young's moduli and polymeric composition during thermo-mechanical conversion of auxetic open cell polyurethane foam. physica status solidi (b), 256 (1).

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Official URL: https://onlinelibrary.wiley.com/doi/full/10.1002/p...
Link to published version:: https://doi.org/10.1002/pssb.201800393
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    Abstract

    The effects of thermo-mechanical auxetic foam conversion parameters on the Young's modulus and Poisson's ratio of open-cell polyurethane foam are related to changes in chemical bonding and cell structure. Applied volumetric compression, conversion temperature and duration are reported on foam Young's modulus, Poisson's ratio and structural stability. Fourier transform infrared spectral analysis on samples converted at and above 160°C strongly indicates a hydrogen bond interaction increase in urea groups (C=O---H-N) and an increase in hydrogen bonding population. Spectral changes inferred soft segment degradation following extensive heat exposure (200°C, 180 minutes), specifically a shift and intensity change in CH2 and C-O-C polyol bands and a broad baseline increase between 3600 and 2400 cm-1. These changes are linked to: i) resistance to dimensional recovery over time and during re-heating, ii) Poisson's ratio becoming negative, then zero in tension or marginally positive in compression, iii) Young's Modulus reducing then increasing, iv) mass loss, evidenced by thermogravimetric analysis increasing from 150°C. The minimum mean values of Poisson's ratio of ~-0.2 (to 10% compression/tension) are comparable to other studies. All samples that retain their imposed compression over time are isotropic, with near constant Young's moduli and Poisson's ratio (to 10 % compression/tension).

    Item Type: Article
    Uncontrolled Keywords: 0204 Condensed Matter Physics; 0206 Quantum Physics; 1007 Nanotechnology; Applied Physics
    Departments - Does NOT include content added after October 2018: Faculty of Science, Technology and Arts > Department of Engineering and Mathematics
    Identification Number: https://doi.org/10.1002/pssb.201800393
    SWORD Depositor: Symplectic Elements
    Depositing User: Symplectic Elements
    Date Deposited: 08 Nov 2018 10:23
    Last Modified: 18 Mar 2021 03:17
    URI: http://shura.shu.ac.uk/id/eprint/23226

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