Moisture Diffusion in Fiber Reinforced Plastics

McKague, E. L.; Reynolds, JD; Halkias, J. E.

doi:10.1115/1.3443342

Cited by 40 publications

(18 citation statements)

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“…In fact, the determination coefficient values (r 2 ) for non-Fickian models were very close to 1, denoting very high correlation between the curve stipulated by the models and the experimental data. It is worth saying that the McKague model [13] also presented high correlation with experimental results. However, it is only a mathematical modification of the Fick's approach, without including any new physical approach to the diffusion problem.…”

Section: Resultsmentioning

confidence: 94%

“…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%

“…A general equation based on the same approach of the Fick law but covering the entire range of absorption was proposed by McKague et al [13] , namely:…”

Section: Fickian Behaviormentioning

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: 94%

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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“…If, after correcting for the fiber content of the composite, there is no difference between the two, interphase effects may be negligible. This in general is found for glass/epoxy systems [25]. Fig.7 shows an example of moisture absorptiondesorption experiment for BT of 70μm thickness [5], where the temperature was kept at 60 o C and the RH level was cycled between 0 and 60%.…”

Section: State Of Moisture Within the Bulk Polymers And Interactions mentioning

confidence: 99%

“…However, in general the pressure field is coupled with the strain changes, which is described previously. The above equation must be solved together with equations (25) and (26).…”

mentioning

confidence: 99%

Mechanics of moisture for polymers: Fundamental concepts and model study

Fan

2008

EuroSimE 2008 - International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronic

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Reliability issues associated with moisture have become increasingly important as advanced electronic devices demand for new materials, more function integration and further miniaturization. However, the fundamentals of the mechanics of moisture transport and the subsequent failures in polymers have not been investigated extensively. This paper is devoted to some fundamental concepts of moisture absorption, diffusion, and swelling. The mathematical descriptions of moisture phase transition with temperature, and the governing equations for a deforming polymer with moisture effect are presented. The non-Fickian sorption behavior is discussed and a widely-used two-stage theory is introduced. It has been found that water sorption (immersion into liquid water bath) has very different transport mechanism at surface compared to the moisture sorption (moisture in air). The state of moisture within polymers and its interactions with polymer matrix, fillers and additives are discussed. It has been suggested that, in most of cases, the majority of absorbed water molecules neither show significant interaction with other water molecules nor with their environment. Those 'unbound' moisture stays in free-volumes and does not contribute to hygroscopic swelling. Swelling is caused by water molecules bound to the polymer matrix. Although the free volume fraction is usually in the range of 1% to 5%, the pore size is always below nanometers and not detectable by the conventional measurement techniques such as SEM and mercury intrusion. An approximate estimate of free volume fraction using weight gain data is introduced. A vapor pressure model, which allows the whole-field vapor pressure calculations, is presented. Finally the governing equations for a deforming polymer with the consideration of moisture are developed.

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Swelling and glass transition relations for epoxy matrix material in humid environments

McKague

Reynolds

Halkias

1978

J of Applied Polymer Sci

196

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SynopsisAn experimental investigation has established coherent data sets describing effects of moisture absorption upon swelling and glass transition of an epoxy resin. Equilibrium moisture absorption levels and resultant swelling can be represented by power law functions of relative humidity and quantity of absorbed moisture, respectively. Depression of glass transition temperature is shown to be described by a relationship derived from free-volume theory. INTRODUCTIONIt is an accepted fact that epoxy matrix composites absorb moisture and that this absorption can alter behavior of certain pr0perties.l The absorption process has been defined in various ways but is reasonably well described by classical diffusion law.2 Altered behavior due to this absorption has been predicted for both loaded and unloaded structures due to swelling of the matrix.3 Methods have been developed which incorporate this hygrothermal conditioning effect into thermal stress analy~is.~ However, coherent data sets describing the swelling behavior have not been reported.Altered mechanical behavior has been observed in matrix dominated properties such as compression strength and shear m o d u l u~.~ Behavior alteration is particularly apparent at elevated temperatures. This has been related to depression of glass transition temperature caused by the moisture absorption.6 It has also been shown that moderate temperature transients can alter the subsequent diffusion behavior of laminates containing certain amounts of moi~ture.~ The importance of these temperature effects requires a coherent data set and theory describing glass transition shifts due to moisture absorption. This paper presents experimental findings of swelling behavior, thermal expansion behavior, and changes in glass transition of an epoxy matrix material resulting from moisture absorption. Theories describing these properties are discussed, and modifications to currently accepted views are proposed. EXPERIMENTALNarmco 5208 epoxy resin was used for all of the investigations discussed in this report. Specimens for all tests were rectangles having a thickness of about 0.035 in. (0.89 mm) and were cut from a neat resin casting. The resin was cured using the cycle shown in Table I.Special care was taken to assure that all specimens were completely dry at the start of testing. The resin casting was kept in a desiccator following cure until individual specimens could be cut with a Micromatic Wafering Saw. The individual specimens were then postcured for 4 hr at 400°F (204OC) and placed immediately into a room-temperature desiccator.One group of specimens was maintained in the reference dry condition. The remainder were placed in groups of three into each of several hygrothermal conditioning environments. The various stagnant-air, constant humidities were provided in laboratory jars containing appropriate saturated salt solutions. The constant temperatures resulted from placing the jars in ovens. Table I1 identifies the environmental conditioning matrix.Specimens from each environmen...

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Moisture Diffusion in Fiber Reinforced Plastics

Cited by 40 publications

References 0 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

Mechanics of moisture for polymers: Fundamental concepts and model study

Swelling and glass transition relations for epoxy matrix material in humid environments

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