Simple quantification of elastomers’ deformation-induced entropy changes through maxwell relation implementation

Abstract

An upper division experimental method to determine the configurational entropy change using an approximated Maxwell relation for short fiber reinforced polymers is presented. This approach mainly integrates two regression models in data analysis, respectively being the phenomenological Mooney-Rivlin model and the linear tension-temperature relation; the former simulates the tensile performance under various isothermal conditions, while the latter is used to measure the partial differential value (∂S/∂l)_Tin the Maxwell relation. To further correct tensile data to accurately measure the minute configurational entropy change in loading, a linear-form segmented compensation function was used to correct the dynamic fatigue effect in repetitive tensile testing. With corrected Mooney-Rivlin fits under various temperature conditions graphed, one may focus on a fixed strain and investigate its corresponding linear tension-temperature relation to establish the numerical value of (∂S/∂l)_T. In this way, the remaining unknown variable in the Maxwell relation is entropy, thereby enabling its mathematical determination. Such a simple experimental design serves as a convenient method to measure configurational entropy change with strain for basic research.