Improving the water resistance of epoxy-anhydride matrices by the incorporation of bentonite

Abstract

Epoxy–anhydride‐based polymers are commonly used as a matrix in pipeline systems exposed to water during their in‐service life. Water absorption at moderate temperatures and/or at long exposure times could lead to irreversible hydrolysis reaction decreasing considerably the polymer overall performance. A strategy to enhance the barrier properties of epoxy resins is to add nanofillers to traditional matrices. In this work, we added bentonite and chemically modified bentonite to this purpose. Water absorption of the resulting materials at three different temperatures (22°C, 80°C, and 93°C) was studied, and simultaneously, the evolution during the immersion tests of glass transition temperature and flexural modulus was recorded. Long‐term gravimetric results showed that composites with chemically modified bentonite produce a delay on the hydrolysis of epoxy–anhydride matrix, which is a relevant result, because of the tough application and uses of the system, from the technological point of view. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of volume fraction on water uptake and tensile properties of epoxy filled with inorganic fillers having different reactivity to water

“…The aging temperature mainly affected the diffusivity of filled epoxy, where the increase of aging temperature increased the diffusivity, as reported by Liu et al [7] on the clay-filled epoxy. However, Capiel et al [13] reported that increasing aging temperature increased both the maximum water uptake and diffusivity on the bentonite-filled epoxy. The increase in water uptake occurred due to the epoxy-anhydride hydrolysis degradation.…”

“…The insignificant effect of MWCNT on the equilibrium water uptake was likely caused by the increase of bonded water due to opening polar groups after introducing MWCNT. Meanwhile, Capiel et al [13] reported the rise of water uptake with the increase of bentonite content aged at temperature of 22°C, which was also caused by increasing the polar groups. The aging temperature mainly affected the diffusivity of filled epoxy, where the increase of aging temperature increased the diffusivity, as reported by Liu et al [7] on the clay-filled epoxy.…”

An Artificial Neural Network (ANN) Model for Predicting Water Absorption of Nanoclay-Epoxy Composites

“…The ANN model allows identifying critical points like the precise temperature at which a particular system's water uptake goes beyond a predefined threshold, work [1], the nano-scale morphology obtained in TBHP-bentonite composites decreases the concentration of water molecules in contact with network backbone, which was confirmed by a smoother Tg versus mass uptake decrease reported in previous publications [1]. The decrease in water-reactive site concentration, produces a reduction on the hydrolysis rate, and extends the service life.…”

“…Many authors have found a considerably improvement in barrier properties of epoxy systems containing small amounts of clay as reinforcement [11]- [18]. The effect on water absorption behavior of adding bentonite and chemically modified bentonite to an epoxyanhydride system was studied in a previous work [1]. It was found that epoxyanhydride systems containing small amounts of chemically modified bentonite show higher water resistance than bentonite-epoxy composites and neat matrix.…”

“…However, hydrolytic degradation may also take place during components service life specially due high temperatures. In order to mitigate the effects of the water diffusive processes in the deterioration of in-service behavior of epoxy matrix composites, the use of chemically modified nanoclays as an additive has been proposed and studied in previous works [1]. In this work, an Artificial Neural Network (ANN) model was developed for better understanding and predicting the influence of modified and unmodified bentonite addition on the water absorption behavior of epoxy-anhydride systems.…”