Constitutive Models for Temperature-, Strain Rate- and Time-Dependent Behaviors of Ionomers in Laminated Glass

Ionomer, which has significant dependency on temperature, strain rate and time, is widely used in structural laminated glass to achieve strong adhesion and high shear transferring ability. In this study, to fix the shortcomings of the current models in describing the characteristic phases and extending application range of ionomers, both experimental and theoretical efforts were made for the constitutive models with introducing the concerned dependency. Uniaxial tensile tests were firstly performed with varying temperatures (−50 to 80 °C) and strain rates (0.001–0.1 s−1). The phenomenological model, DSGZ, was then employed to describe the characteristics of the overall stress–strain curves at different temperatures and strain rates. The comprehensive comparison study shows that the constitutive models can well-describe all the characteristic phases in both glassy and rubbery state. It was followed by conducting dynamic mechanical analysis (DMA) tests to identify the time sensitivity of ionomers. A temperature–frequency sweep at a wider temperature range (−50–100 °C) than current reports was adopted in DMA tests. Williams–Landel–Ferry (WLF) model was utilized to describe the time–temperature superposition, which was subsequently combined with generalized Maxwell model to fit and predict the relationship between relaxation modulus, time and temperature.