Thermo-Mechanical Creep and Recovery of CTBN–Epoxy Shape Memory Polymers Under Saline Environment

Abstract

In the present study, the creep and recovery experiments of unmodified epoxy SMP and 5% carboxyl-terminated butadiene acrylonitrile (CTBN) modified epoxy SMPs were carried out after being exposed to saline environment (5% NaCl, 35 °C/98% RH). The creep results of the SMP specimens before and after exposure to saline environment, obtained through short-term tensile creep test at different temperatures (i.e., 25, 80, 103 and 120 °C) and loading conditions, were compared. Prior to exposure to saline environment, the creep strain was found to increase with increasing temperature and reached a maximum around the glass transition temperature (i.e., 103 °C). A higher creep recovery ratio was noticed in the CTBN-modified epoxy SMP particularly at high-temperature conditions. The creep strain was higher in saline environment at 25, 80 and 103 °C; however, at 120 °C both the SMPs could not withstand the applied load. The creep recovery ratio was unaffected by the saline environment in both the SMPs.