Diffusion of moisture into two-phase polymers

Jacobs, P. M.; Jones, Elizabeth R.

doi:10.1007/bf01174494

Cited by 35 publications

(23 citation statements)

References 11 publications

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“…Namely, a dense phase with a large number of crosslinks and a less dense phase with fewer crosslinks, as predicted by the models of Jacobs and Jones [21,22] . For all formulations tested, the proportion of the dense phase present in the system was superior to that of the "less" dense phase, what is depicted by the high volume fraction obtained for the dense phase (V d ).…”

Section: Resultsmentioning

confidence: 83%

“…The lack of consistence of the Carter and Kibler model can be explained regarding that the boundary conditions stablished by Equation 13 were not satisfied -i.e., the values obtained to both a and b are greater than To verify the results listed at Table 2 for V d , the graphical methodology described at the work of Jacobs and Jones [21,22] was also used. The complete description of the graphical approach can be found at the works of Jacobs and Jones [21,22] , and is not reproduced here for the sake of shortness.…”

Section: Resultsmentioning

confidence: 99%

“…These models take new assumptions such as water molecules acting both as a bound and unbound phase [18][19][20] . or considering that polymers can have phases with different macromolecular structures (for example, regions heavily crosslinked and regions with light crosslinking) [21,22] . Some of these models also include a term considering that stress relaxation can occur due to swelling after water uptake [23,24] .…”

Section: Non-fickian Behaviormentioning

confidence: 99%

“…At region II, diffusion occurs more slowly, and the water uptake is attributed only to diffusion at the dense phase, since saturation has already occurred at the less crosslinked phase [21] . To model the behavior of this two-phase polymer, the equation developed by Jacobs and Jones assumed that diffusion is governed by a Fickian behavior at both phases [21,22] . The resultant equation is as follow:…”

Section: Jacobs-jones Modelmentioning

confidence: 99%

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Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Pereira

d’Almeida

2016

Polímeros

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SbstractThe water absorption behavior of the DGEBA/TETA epoxy system was evaluated as a function of the epoxy monomer to amine hardener ratio. Weight gain versus immersion time curves were obtained and the experimental points were fitted using Fickian and Non-Fickian diffusion models. The results obtained showed that for all epoxy monomer to hardener ratios analyzed water diffusion followed non-Fickian behavior. It was possible to correlate the water absorption behavior to the macromolecular structure developed when the epoxy/ hardener ratio was varied. All epoxy/hardener ratios present a two-phase macromolecular structure, composed of regions with high crosslink density and regions with lower crosslinking. Epoxy rich systems have a more open macromolecular structure with a lower fraction of the dense phase than the amine rich systems, which present a more compact two-phase structure.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Non-fickian Behaviormentioning

confidence: 99%

Section: Jacobs-jones Modelmentioning

confidence: 99%

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Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Pereira

d’Almeida

2016

Polímeros

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“…This behavior can be modeled by a two-mode desorption process originally put forward by Jacob and Jones 29,30 and later modified by Maggana and Pissis 31 to describe the diffusion of water in epoxy networks. These authors adopted the Shen and Springer equation originally used for the diffusion of vapors through glass-fiber composites, assuming that epoxy networks contain two phases, differing only with respect to their density and each having a different diffusivity.…”

Section: Spectroscopic Determination Of the Water Diffusion Parametersmentioning

confidence: 99%

Probing the molecular interactions in the diffusion of water through epoxy and epoxy–bismaleimide networks

Musto

Ragosta

Scarinzi

et al. 2002

J Polym Sci B Polym Phys

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ABSTRACT:Fourier transform infrared spectroscopy in the near-infrared (NIR) frequency range was used to investigate the molecular interactions occurring between absorbed water molecules and networks based on a tetrafunctional epoxy resin. One of these networks was a typical formulation containing 4,4Ј-diamino diphenylsulfone as a hardener, and the other was a modified resin containing 4,4Ј-bismaleimide-diphenylmethane (BMI) as a coreactive monomer. Molecular spectroscopy analysis confirmed the existence of mobile water localized into network defects (microvoids) that did not interact with the networks and water molecules bound to the networks through hydrogen-bonding interactions. In the BMI-containing system, the fraction of bound water decreased significantly with respect to the unmodified epoxy resin. This was a relevant result because the bound water was primarily responsible for the plasticization of the network and for the consequent worsening of mechanical performance. Water diffusion was investigated with gravimetric sorption measurements and time-resolved Fourier transform NIR spectroscopy measurements. These showed that the presence of BMI decreased the water uptake at equilibrium, enhanced the diffusivity, and reduced the activation energy for diffusion. A dual-mode model for diffusion was found to be suitable for accurately describing the mass-transport process in both investigated systems. The results of the model simulations allowed us to estimate the ratio of free and bound water, which was in good agreement with that obtained from the spectroscopic analysis.

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Water sorption and diffusion studies in an epoxy resin system

Maggana

Pissis

1999

J. Polym. Sci. B Polym. Phys.

214

112

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The kinetics of water absorption in epoxide materials was studied by the aid of a diglycidyl ether of bisphenol‐A–triethylenetetramine (DGEBA–TETA) epoxy–resin system containing various amounts of the plasticizer THIOCOL (0–40 phr). The presence of plasticizer permits the formation of products with different crosslinking densities and hydrophilic characters. Dynamic water absorption experiments were carried out at 15, 40, and 70°C. For the fitting of the experimental results, a new model was used, based on a model proposed earlier by Jacobs and Jones. This model considers epoxide product as a two‐phase system consisting of a master phase (where the major part of the water is absorbed), which is homogeneous and nonpolar (phase 1), and of a second phase with different density and/or hydrophilic character (phase 2). By making the assumption that water diffusion can take place independently in the different phases of the material in accordance with Fick's second law, we can calculate the diffusion coefficient D and the water content at saturation M∞ for each phase separately. Equilibrium water sorption measurements were performed at 40°C, and the data were analyzed and discussed based on the Guggenheim–Anderson–de Boer (GAB) equation, the results being in support of the two‐phase model used in the analysis of absorption kinetics. The linear expansion coefficient and the glass transition temperature of the materials, employed in the discussion of the results, were measured by thermomechanical analysis. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1165–1182, 1999

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Diffusion of moisture into two-phase polymers

Cited by 35 publications

References 11 publications

Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Effect of the hardener to epoxy monomer ratio on the water absorption behavior of the DGEBA/TETA epoxy system

Probing the molecular interactions in the diffusion of water through epoxy and epoxy–bismaleimide networks

Water sorption and diffusion studies in an epoxy resin system

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