Water transport through epoxy-based powder pipeline coatings

Zargarnezhad, Hossein; Asselin, Edouard; Wong, Dennis; Lam, C.N. Catherine

doi:10.1016/j.porgcoat.2022.106874

Cited by 14 publications

(32 citation statements)

References 59 publications

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“…( 8)) in a glassy polymer by fitting data from vapor sorption experiments to this equation [36]. Since the vapor transport properties of FBE agree reasonably well with published data for other epoxy formulations [9], we applied Eq. ( 8) and solubility data from the literature [39] for epoxy to determine the modified DMS parameters.…”

Section: Models Developed For Competitive Permeation At Elevated Temp...mentioning

confidence: 94%

“…Thus, we use vapor sorption data in epoxy based on the multilayer sorption theory for our mathematical modeling. Microstructural characterization of the FBE coating in the presence of water vapor has been discussed in detail elsewhere [9]. In all experiments, the downstream volume was connected to a relief compartment to maintain the total pressure of the gas phase in the downstream chamber at atmospheric pressure.…”

Section: Dissolved Oxygen Permeationmentioning

confidence: 99%

“…Thus, applying this theory gives us a means to evaluate water/gas permeability trade-offs in glassy polymers. Thus, we used the Freeman theoretical model to estimate the epoxy coatings' performance prior to initiation of water-induced plasticization effects (i.e., < 65°C [9]).…”

Section: H2o/o2 Upper Bound Relationship At Ambient Temperaturesmentioning

confidence: 99%

“…The dissolved gas permeation rate through water-saturated films was empirically determined according to water activities in the upstream gas phase. We also applied mathematical models developed for glassy polymers to quantify adjustable parameters of competitive sorption based on our previously reported water permeability data [9] and on sorption data available in the literature. Then, permeation of water and oxygen through coating layers was directly modeled and described according to sorption and diffusion concepts for competitive transport.…”

Section: Introductionmentioning

confidence: 99%

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Transport of water and oxygen in epoxy-based coatings

Zargarnezhad

Zarei

Wong

et al. 2022

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Epoxies are used in various industrial applications as corrosion barriers but quantitative time-dependent predictions of their ability to mitigate corrosion attack at the metal/coating interface remain elusive. Permeability data for water and oxygen through epoxy-based coatings are of particular interest because the coating’s barrier performance in humid environments is directly related to how quickly these reactants get to the metal/coating interface. There is, however, an absence of literature data to explain oxygen transport within coatings in the presence of condensed water and its associated plasticization effects. We show that water is a dominant player in the barrier performance of epoxy coatings because it blocks the transport of other permeants. Through analysis of the sorption isotherms and empirical permeation data, we determined adjustable parameters that explain water vapor plasticization effects in fusion bonded epoxy (FBE) at 65°C. At this temperature, evolution of cavity formation and break-up of water clusters result in high mobility of water molecules inside the epoxy network. We also modeled oxygen transport through FBE in wet-state conditions based on time lag measurements, and with reported literature data on vapor and gas sorption in epoxy. In a mixed gas/vapor system, condensed water in FBE blocks and/or significantly decreases gas permeation in the coating. If the service temperature is low (less than 40°C), water immobilizes the oxygen gas within microvoid regions in the glassy epoxy. Our experimental measurements, combined with Freeman’s theoretical model for upper bound limits, showed that this water-induced blocking mechanism is sufficient to suppress corrosion reactions on the underlying substrate material. At 65°C and above, the synergistic effect of coating plasticization by water molecules and dissolution of oxygen in a mobile water phase results in significant gaseous transport. We applied mathematical models based on proven sorption and transport models to FBE free-standing films and derived adjustable parameters to quantitatively explain this competitive permeation. Our O2 transport data show that, compared to the single-layer FBE, epoxy-based coatings with additional polyolefin layers can improve the barrier performance by deprivation of micropore channels for gas transport.

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Section: Models Developed For Competitive Permeation At Elevated Temp...mentioning

confidence: 94%

Section: Dissolved Oxygen Permeationmentioning

confidence: 99%

Section: H2o/o2 Upper Bound Relationship At Ambient Temperaturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Transport of water and oxygen in epoxy-based coatings

Zargarnezhad

Zarei

Wong

et al. 2022

Preprint

Self Cite

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“…Yet to our knowledge, there is no study on oxygen permeability of epoxybased coatings in wet-state conditions, which are common in most applications of these coatings [17]. Since the permeability coefficient of water in FBE is high (10 −13 mol/m-s-Pa at 25°C [9]) and transport of water-dissolved oxygen through the glassy coating is anticipated [18], we might expect dissolved oxygen transport. In addition, at high activities, water molecules tend to self-associate rather than interact with the polymeric chains [19].…”

Section: Introductionmentioning

confidence: 99%

Competitive transport of water vapor and oxygen in epoxy-based coatings

Zargarnezhad

Zarei

Wong

et al. 2022

Preprint

Self Cite

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Epoxies are used in various industrial applications as corrosion barriers but quantitative time-dependent predictions of their ability to mitigate corrosion attack at the metal/coating interface remain elusive. Permeability data for water vapor and oxygen through epoxy-based coatings are of particular interest because the coating’s barrier performance in humid environments is directly related to how quickly these reactants get to the metal/coating interface. There is, however, an absence of literature data to explain oxygen transport within coatings in the presence of water vapor and its associated plasticization effects. We show that water vapor is a dominant player in the barrier performance of epoxy membranes because it blocks the transport of other permeants. Through analysis of the sorption isotherms and empirical permeation data, we determined adjustable parameters that explain water vapor plasticization effects in fusion bonded epoxy (FBE) at 65°C. At this temperature, evolution of cavity formation and break-up of water clusters result in high mobility of water vapor molecules inside the epoxy network. We also modeled oxygen transport through FBE in wet-state conditions based on time lag measurements, and with reported literature data on vapor and gas sorption in epoxy. In a mixed gas/vapor system, water vapor in FBE blocks and/or significantly decreases gas permeation in the coating. If the service temperature is low (less than 40°C), water vapor immobilizes the oxygen gas within microvoid regions in the glassy epoxy. Our experimental measurements, combined with Freeman’s theoretical model for upper bound limits, showed that this water-induced blocking mechanism is sufficient to suppress corrosion reactions on the underlying substrate material. At 65°C and above, the synergistic effect of coating plasticization by water molecules and dissolution of oxygen in a mobile water vapor phase results in significant gaseous transport. We applied mathematical models based on proven sorption and transport models to FBE membrane systems and derived adjustable parameters to quantitatively explain this competitive permeation. Our O2 transport data show that, compared to the single-layer FBE, epoxy-based coatings with additional polyolefin layers can improve the barrier performance by deprivation of micropore channels for gas transport.

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