Epoxy‐water interactions

Abstract

It has been shown that sorbed moisture plasticizes epoxy resins with a resultant depression in the glass transition temperature of the polymer. The nature of the epoxy‐water interaction still requires further investigation. The equilibrium sorption and diffusion of water in a high Tg epoxy is examined. Other analytical techniques including differential scanning calorimetry, infrared spectroscopy, electron microscopy and nuclear magnetic resonance are applied to the system. Experimental results suggest that the sorbed water at low concentrations is strongly localized at specific segments or groups in the polymer. Discussion is given relative to the structure‐properties of the epoxy and its possible correlation to the experimental data obtained.

Predictive Model for Tensile Properties of Carbon Fiber-Reinforced Polymers at Various Moisture Contents

“…Water absorbed into polymer can be categorized into two groups: free water and bound water (Moy and Karasz 1980;Pethrick et al 1996;Nogueira et al 2000). For the current model, bound water is considered to be the main cause of the reduction in mechanical properties of the polymer.…”

“…The effective additive properties are given in Equations (5) to (8). The values of the additive properties used in this study are obtained from (Van Krevelen and Te Nijenhuis 2009).…”

“…Pethrick et al used dielectric measurements to study the water-epoxy interactions and found that water exists in two different states in epoxy: water is bound to epoxy molecules via hydrogen bonds and water molecules that form clusters in the epoxy sub-micro-cavities (Pethrick et al 1996). The water-epoxy interaction leads to a plasticization effect on the epoxy resulting in a decrease in glass transition temperature, Tg (Moy and Karasz 1980). The mechanical properties of neat epoxy are also reduced with the increase of water content (Nogueira et al 2000;Zafar et al 2012).…”

Influence of water absorption on dielectric properties of epoxy SiO2 and BN nanocomposites

“…Two kinds of water present in epoxy and its nanocomposites [8,13]. Free water is located in free volume holes, cracks and crevices in matrix.…”

Mapping water uptake in an epoxy-phenolic coating

“…However, some degree of water uptake is characteristic of epoxy resins, and has been demonstrated to induce swelling, [15] [16] hydrolysis, [17][18] crazing, [19] cracking, [20] plasticization [21] and lowering of the Tg. [22][23] Localised water uptake by epoxy components may therefore represent failure points in the mechanical integrity of a coating, compromising barrier properties. A comprehensive understanding of the macromolecular structures underpinning water sorption is therefore a key step towards the delivery of coatings with improved long term properties.…”