A network-based transversely isotropic visco-hyperelastic constitutive model accounting for pendant chains

Abstract

Crosslinked polymeric films are widely used as a bonding component in flexible electronic devices. The ultra-thin polymeric materials are often transversely isotropic and visco-hyperelastic in response to a wide range of strains. The mechanical properties of such adhesives are a crucial part of the design process and device reliability evaluation. In this paper, we perform systematic investigation by characterizing the mechanical behavior of a typical group of optically clear adhesives (OCAs). By including the influence of pendant chains on the mechanical behaviors of OCAs under different loading conditions, we propose a network-based constitutive model for those OCAs, where a hyperelastic response originates from the crosslinked and entanglement networks and a viscous effect comes from free chains and pendant chains. The model is applied to predict the mechanical response of four commercially available 3M OCAs. Results show that our model can predict the mechanical response of OCAs well. We expect the experiment observation and the developed modelling may help in understanding the mechanical behavior of a wide range of polymeric adhesives for engineering practice.