Research on viscoelastic behavior of semi‐crystalline polymers using instrumented indentation

Abstract

In this study, the viscoelastic behavior of a polyamide 12 (PA12) polymer was evaluated using instrumented indentation technology based on a rheological model. The creep compliance and retardation spectra were obtained to analyze the viscoelastic response during the holding stage according to the rheological model under different preloading conditions. The results showed that the viscoelastic responses were independent of the indentation depth or load under step loading conditions. However, the creep compliance increases, and the peak intensity of the retardation spectrum decreases with a decrease in the preloading rate owing to the structural relaxation observed during the preloading stage under ramp loading conditions. Furthermore, softening dispersion can be completed during the loading stage under continuous stiffness measurement (CSM) conditions. As the preloading strain rate changes, the peak of the retardation spectrum gradually decreases until it disappears completely. Moreover, studies on indentation creep using the CSM method are challenging because of the complicated viscoelastic response observed during the preloading stage.

The Study Influence Analysis of the Mathematical Model Choice for Describing Polymer Behavior

“…In addition, if, in the first type there, is a trace of plastic deformations, the second type will have insignificant plastic deformations. Studies aimed at analyzing both the viscoelastic-plastic behavior of materials [24][25][26][27] and viscoelastic behavior of materials [28][29][30] are gaining momentum. The paper considers a mathematical model of only viscoelastic behavior for the first stage of the study.…”