Cyclic moisture sorption and its effects on the thermomechanical properties of epoxy and epoxy/MWCNT nanocomposite

Funding Information: This research was funded by ERDF project No. 1.1.1.2/VIAA/1/16/066 for the support of the post-doctoral research project "Environmental effects on physical properties of smart composites and fiber-reinforced plastics modified by carbonaceous nanofillers for structural applications". Publisher Copyright: © 2019 by the authors.The aim of this work was to reveal the moisture absorption-desorption-resorption characteristics of epoxy and epoxy-based nanocomposites filled with different multiwall carbon nanotubes (MWCNTs) by investigating the reversibility of the moisture effect on their thermomechanical properties. Two types of MWCNTs with average diameters of 9.5 and 140 nm were used. For the neat epoxy and nanocomposite samples, the moisture absorption and resorption tests were performed in atmospheres with 47%, 73%, and 91% relative humidity at room temperature. Dynamic mechanical analysis was employed to evaluate the hygrothermal ageing effect for unconditioned and environmentally "aged" samples. It was found that moisture sorption was not fully reversible, and the extent of the irreversibility on thermomechanical properties was different for the epoxy and the nanocomposite. The addition of both types of MWCNTs to the epoxy resin reduced sorption characteristics for all sorption tests, improved the hygrothermal and reduced the swelling rate after the moisture absorption-desorption.publishersversionPeer reviewe