A discussion of the molecular mechanisms of moisture transport in epoxy resins

Soles, Christopher L.; Yee, Albert F.

doi:10.1002/(sici)1099-0488(20000301)38:5<792::aid-polb16>3.0.co;2-h

Cited by 276 publications

(213 citation statements)

References 27 publications

(30 reference statements)

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“…The amount of free volume is considered as the main driving force to water absorption, and is related to several different physical characteristics of the polymer [15,16,[28][29][30][31] . These physical characteristics are intimately linked to the degree of cure, the stoichiometric ratio and with the stiffness of the molecular bonds [29][30][31] .…”

Section: Resultsmentioning

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: 99%

“…These physical characteristics are intimately linked to the degree of cure, the stoichiometric ratio and with the stiffness of the molecular bonds [29][30][31] . The chemical affinity of a polymer to water, by the other side, is attributed to the …”

Section: Resultsmentioning

confidence: 99%

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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“…[30][31] The term "epoxy resin" is a general descriptor that includes a variety of different monomers with a variable extent of hydrophilic groups that contribute differentially to water sorption and diffusion through polymerized resin matrices. [32][33][34] Unfortunately, the types of silane and epoxy resin utilized in fiber posts are regarded as proprietary information by the manufacturer and were not available to the authors. The phenomenon may be prevented with the application of more hydrophobic coatings 36 or by selecting alternative strategies of post superficial treatment, such as sandblastings, 36 allowing a more hydrolitically stable micromechanical bonding mechanism.…”

Section: Discussionmentioning

confidence: 99%

In Vitro Hydrolytic Degradation of Composite Quartz Fiber-post Bonds Created by Hydrophilic Silane Couplings

Monticelli¹,

Osorio²,

Toledano³

et al. 2006

Operative Dentistry

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©Operative Dentistry, 2006, 31-6, 728-733 F Monticelli • R Osorio M Toledano • FR Tay • M Ferrari Clinical RelevanceSilane-based composite bonds are susceptible to hydrolytic degradation: interfacial water sorption induced by hydrolytic couplings may adversely affect their strength. SUMMARYThe hydrolytic stability of a pre-activated MPS silane (Monobond-S) and a 2-component 4-META/ γ γ-MPTS silane (Porcelain Liner M) to H 2 O 2 -etched quartz fiber posts was investigated using a modeling approach. Composite build-ups around silanized posts were stored dry for 24 hours, stored in deionized water at 37°C for 24 hours, 1 week, 1 month or they were thermocycled. Sectioned specimens were prepared for microtensile bond testing and SEM examination; 4-META/γ γ-MPTS silane produced a rapid decline in bond strength after 1 week and 1 month of water storage and after thermocycling. This was not apparent in pre-activated MPS silane. SEM revealed debonding along the post-composite interfaces, which were coupled with 2-component silane. The use of a hydrophilic resin monomer (4-META) for on-demand hydrolysis of the γ γ-MPTS silane expedited interfacial water sorption and hydrolytic degradation, which may be prevented with alternative coupling strategies.

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“…However, its strength varies from one sample to another. This relaxation is generally attributed to the rotation of the hydroxyether groups that are generated due to the crosslinking reaction between the epoxy and amine groups [49][50][51], and its strength should therefore be related to the crosslinking density of the epoxy network. For the 2 wt% filled nanocomposites, the strength of the b relaxation for samples E/100H/ 2SiN and E/90H/2SiN is not significantly different from that of the reference sample since the crosslinking density in these samples, deduced from T g , is not markedly affected.…”

Section: Dielectric Spectramentioning

confidence: 99%

Influence of filler/matrix interactions on resin/hardener stoichiometry, molecular dynamics, and particle dispersion of silicon nitride/epoxy nanocomposites

et al. 2017

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The addition of nanofillers can have a significant influence on the resin stoichiometry of thermosetting polymer systems. Based on differential scanning calorimetry (DSC) results, it is estimated that the inclusion of 2 and 5 wt% of silicon nitride nanofiller displaces the resin/hardener stoichiometry of an epoxy/amine network by 6.5 and 18%, respectively. Dielectric spectroscopy results confirm the above findings, in that the spectra of the nanocomposite samples were found to be equivalent to the spectra of unfilled samples when the above stoichiometric effect was taken into account. Therefore, this study provides clear evidence that the presence of a nanofiller can directly and significantly affect the curing process of an epoxy network. Consequently, this should always be considered when introducing nanofillers into thermosetting matrices. These results indicate the presence of covalent bonding between the nanoparticles and the surrounding polymer and, therefore, provide an opportunity to explore the influence of this bonding on the molecular dynamics of the polymer layer around the particles. However, the obtained DSC and dielectric spectroscopy results suggest that, in the system considered here, either the covalent bonding does not have an appreciable influence on the segmental dynamics of the polymer, as revealed by these techniques, or that the thickness of the affected layer is less than 1 nm and therefore too small to be distinguished from experimental uncertainties.

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A discussion of the molecular mechanisms of moisture transport in epoxy resins

Cited by 276 publications

References 27 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

In Vitro Hydrolytic Degradation of Composite Quartz Fiber-post Bonds Created by Hydrophilic Silane Couplings

Influence of filler/matrix interactions on resin/hardener stoichiometry, molecular dynamics, and particle dispersion of silicon nitride/epoxy nanocomposites

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