Influence of two‐phase behavior of ethylene ionomers on diffusion of water

Abstract

In this study, diffusion of water into ethylene ionomers neutralized with sodium or zinc cations (Na‐ionomer and Zn‐ionomer, respectively) was studied by in situ Fourier transform near infrared (NIR) spectroscopy. Water ingress was measured by NIR from the edge of the laminated glass toward the center and the measured water concentration profiles were analyzed by Fick's second law or the modified Jacobs–Jones model, which describes diffusion into a two‐phase system of different density and polarity. It was found that the modified Jacobs–Jones model agrees well with the measured water concentration profiles of ionomers, while the Fickian model fits well to the poly(vinyl‐butyral) (PVB) results. The modified Jacobs–Jones model was also confirmed to apply to water vapor transmission rate (WVTR) data of another sodium ionomer (Na‐ionomer‐HTM) with a higher melting temperature than Na‐ionomer. The water diffusion coefficient for Na‐ionomer, Zn‐ionomer, and PVB are compared, and the diffusion parameters are discussed considering the higher‐ordered structures of ionomers studied by small‐angle X‐ray scattering (SAXS). Simulating conditions that PV modules encounter in field applications, model projections show that Zn‐ionomer and Na‐ionomer‐HTM give significantly lower water permeation than PVB, and due to its low diffusion coefficient, Na‐ionomer will have significantly less water ingress than PVB. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48929.

Influence of co‐neutralization by sodium and zinc on the ethylene ionomer structure and properties

“…The value of β for EMAA‐Zn is computed to be 0.3, meaning only 30% of zinc cations are incorporated into ionic multiplets. This is similar to values reported in the literature 3,17 . The mixed ionomers, however, give β of 0.7–0.8, indicating that the mixed sodium cations promote zinc cations to form or be incorporated into ionic multiplets.…”

“…Figure 1 shows the amount of water absorbed in ionomers and the number of water molecules per cation at 40°C. Reflecting the nature of the cations that the zinc ions are divalent (bifunctional) and the sodium ions are monovalent, 17 EMAA‐Na gave the largest amount of water absorption. After 96 h of soaking, the water content in EMAA‐Na was 6.4 wt%, which equals to 4.0 water molecules per one cation.…”

“…This is similar to values reported in the literature. 3,17 The mixed ionomers, however, give β of 0.7-0.8, indicating that the mixed sodium cations promote zinc cations to form or be incorporated into ionic multiplets. This is in agreement with the v p changes.…”

Preparation of laminated safety glass based on high strength polyurethane film by solution annealing

“…The PVB owns excellent bonding strength, but water absorption of PVB will lead to less safety for laminated glass. 6,7 Under the action of ultraviolet light, the EVA material will turn yellow under long-term illumination, reducing the transmittance of laminated glass. 8 Polyurethane material is expected to be the preferred material for laminated glass.…”

“…The common intermediate materials include ethylene vinyl acetate (EVA), polyvinyl butyral (PVB), thermoplastic polyurethane (TPU), etc. The PVB owns excellent bonding strength, but water absorption of PVB will lead to less safety for laminated glass 6,7 . Under the action of ultraviolet light, the EVA material will turn yellow under long‐term illumination, reducing the transmittance of laminated glass 8 .…”