Mechanical properties of viscoelastic materials subjected to thermal-oxidative aging: An experimental and theoretical study

Viscoelastic materials (VEMs) made from rubber polymer will inevitably age due to the interactions with the harmful environment during service life, thus reducing the reliability of viscoelastic (VE) damping equipment installed in building structures. In order to understand and be able to predict the degradation of VE damping equipment, it is imperative to comprehensively study the influence of aging on the mechanical properties of VEMs. In this paper, a series of thermal-oxidative (TO) aging tests and mechanical property tests are conducted on our previously developed VEMs to study effects of TO aging on the molecular chain structure and corresponding changes of macroscopic mechanical properties of VEMs. By classifying molecular chains of VEMS into elastic chains and free chains, the effects of different chemical reactions during TO aging on these two main chains and corresponding changes on macroscopic mechanical behaviors of VEMs are analyzed. This facilitates formulating a mathematical model that can characterize the mechanical behavior of TO aging VEMs. In conjunction with the experimental data, the accuracy and applicability of the proposed model are compared and verified. Sensitivity analyses of parameters involved in the proposed model are then performed. The experimental results demonstrate that the TO aging can degrade the deformation capability and harden the modulus of VEMs, which may adversely affect the performance of VE damping devices. The parameter analyses depict that the TO aging affects the macroscopic mechanical behavior of VEMs by altering the relative number and configuration of free chains and elastic chains as well as their respective contributions to the total stress of VEMs. The results point to the high accuracy of the proposed model in representing the strain-stress behavior of VEMs under different aging conditions.

Automated summary

This paper comprehensively studies the influence of thermal-oxidative aging on the mechanical properties of viscoelastic materials (VEMs). By conducting thermal-oxidative aging tests and mechanical property tests, the authors analyze the effects of different chemical reactions during aging on the molecular chain structure and macroscopic mechanical behaviors of VEMs. A mathematical model is formulated to characterize the mechanical behavior of aging VEMs and is compared and verified using experimental data. The results demonstrate that thermal-oxidative aging can degrade the deformation capability and harden the modulus of VEMs, affecting the performance of VE damping devices.