Unraveling the high strain-rate dynamic stiffening in select model polyurethanes - the role of intermolecular hydrogen bonding

POLYMER

卷:168

Article

Wu, You-Chi Mason^1,2  Hu, Weiguo³  Sun, Yuchen^1,2  Veysset, David¹  Kooi, Steven E.¹  Nelson, Keith A.^1,2  Swager, Timothy M.^1,2  Hsieh, Alex J.^1,4 

[1] MIT, Inst Soldier Nanotechnol, 77 Massachusetts Ave, Cambridge, MA 02139 USA

[2] MIT, Dept Chem, Cambridge, MA 02139 USA

[3] Univ Massachusetts, Dept Polymer Sci & Engn, Amherst, MA 01003 USA

[4] US Army, Res Lab, FCDD RLW MG, Aberdeen Proving Ground, MD 21005 USA

关键词: Polyurethane elastomers;    High strain-rate deformation;    Dynamic stiffening;    Laser-induced micro-particle impact test;    Intermolecular hydrogen bonding;    Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy;    Solid-state nuclear magnetic resonance (ssNMR) spectroscopy;    Dynamics at the molecular level;    Coefficient of restitution;   

DOI  :  10.1016/j.polymer.2019.02.038

来源: Elsevier

【 摘 要 】

This study elucidates the influence of molecular attributes on the observed dynamic stiffening in select two-component polyurethanes upon high strain-rate impact. Unlike typical segmented elastomers, polyurethanes consisting of poly(tetramethylene oxide), PTMO, and a diisocyanate, but without a chain extender, are investigated. The hexamethylenediisocyanate (HDI)-based polyurethane, HDI - PU, exhibits crystallinity and a much higher ambient storage modulus, as determined by dynamic mechanical analysis at 1 Hz, than that of 4,4'-methylenediphenyldiisocyanate (MDI)-based polyurethane, MDI - PU. In contrast, MDI - PU exhibits a higher glass transition temperature than that of HDI - PU, and a greater dynamic stiffening against silica micro-particle impacts at strain rates between 10(7) and 10(8) s(-1). The variation in dynamic stiffening corroborates well the observed dynamics at the molecular level, as determined via solid-state nuclear magnetic resonance (ssNMR) spectroscopy. The presence of a slower-dynamics component in MDI - PU, as evidenced in the C-13 ssNMR dipolar dephasing time, is used to explain the observed enhanced dynamic stiffening response.

【 授权许可】

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