Cyclic Moisture Sorption and its Effects on the Thermomechanical Properties of Epoxy and Epoxy/MWCNT Nanocomposite.

Tatjana Glaskova-Kuzmina,Andrey Aniskevich,Anna Borriello,Jevgenijs Sevcenko,Mauro Zarrelli

doi:10.3390/polym11091383

Abstract

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.

Highlights

The addition of nanoparticles to traditional polymer resins allows the final material properties to be tuned by changing the concentration and morphology of the nanoparticles
Multiwall carbon nanotubes (MWCNTs) have unique mechanical properties; their stiffness and strength values are within the range of 100–1000 and 2.5–3.5 GPa, respectively, and their electrical conductivity is 3000–4000 S/m
The characteristics of moisture absorption–desorption–resorption of epoxy and epoxy-based NC filled with different MWCNTs were estimated and the reversibility of the moisture effect on their thermomechanical properties was determined

Summary

Introduction

The addition of nanoparticles to traditional polymer resins allows the final material properties to be tuned by changing the concentration and morphology of the nanoparticles. Multiwall carbon nanotubes (MWCNTs) have unique mechanical properties; their stiffness and strength values are within the range of 100–1000 and 2.5–3.5 GPa, respectively, and their electrical conductivity is 3000–4000 S/m. Such properties make them valuable candidates to develop novel composites characterized as advanced polymer materials [1,2]. To date, such materials have been limited mostly to indoor applications due to the relative sensitivity of the mechanical properties of polymers and polymer composites to environmental conditions, such as moisture and temperature [3]. The analysis of the available literature revealed contradictory information on the reversibility of hygrothermal effects on the structure and mechanical properties of epoxy [3,4,5] and epoxy-based nanocomposite (NC) [6,7,8].

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