Effect of the fiber orientation on the sorption kinetics of seawater in an epoxy/glass composite: A free‐volume microprobe study

Radha, J.C.; Ranganathaiah, C.

doi:10.1002/app.28100

Cited by 4 publications

(4 citation statements)

References 32 publications

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“…The moisture is not lost but is moving into the matrix and becoming molecularly dispersed. This effect has been observed previously with other epoxy systems . The rise after 332 h exposure followed by a decrease again (both above the initial starting value) reflecting the moisture filling the voids which can collapse as the water is re‐dispersed.…”

Section: Resultssupporting

confidence: 82%

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A dielectric study of water uptake in epoxy resin systems

Garden¹,

Pethrick²

2017

J of Applied Polymer Sci

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The influence of epoxy resin formulation on the nature and extent of moisture is studied using dielectric and gravimetric analysis for samples cured at 40, 50, 60, and 70 8C and aged at 50 8C and 70 8C. The equilibrium moisture uptake depends on the difference between the glass transition and aging temperature. Dielectric relaxation data measured from 1 to 3 3 10 10 Hz indicates the presence of water in at least two different environments. The high frequency relaxation ca. 1 3 10 10 Hz is associated with water clustered in nano-voids, whereas the relaxation at 10 5 Hz arises from a combination of OH pendant group reorientation motion coupled with that of molecularly dispersed water molecules. A correlation exist between the dielectric permittivity and the amount of moisture absorbed. Water initially resident in voids is re-dispersed with aging into the resin matrix aiding plasticization and allowing densification of the matrix. The extent to which changes occur depends on the chemical functions forming the matrix and densification leads to a drop in the amount of water absorbed. In the complex resin systems, water interacts with both OH groups and polyether of the amine curing agent which is not possible with the aliphatic diamine in the simple system.] V C 2017 Wiley Periodicals, Inc. J. Appl. Polym.Sci. 2017, 134, 44717.

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Section: Resultssupporting

confidence: 82%

“…The relaxation located ∼100 KHz is ascribed to dipole reorientation of OH groups and water molecules attached to the hydroxyl groups of the epoxy matrix. Plots of the permittivity and loss measured at 1 kHz reflect the changes in the total dipole relaxation for both “bound” and “free” in the resin, Figure (a,b).…”

Section: Resultsmentioning

confidence: 99%

A dielectric study of water uptake in epoxy resin systems

Garden¹,

Pethrick²

2017

J of Applied Polymer Sci

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“…From the microscopic viewpoint, fiber architecture is an important aspect that can influence the moisture diffusion. Therefore, there is a need to accurately model the ingress of moisture into composites [14][15][16][17]. As the fiber diameter is fairly small in comparison with its length, most of the researches have been conducted using two-dimensional models.…”

Section: Introductionmentioning

confidence: 99%

A framework for three-dimensional finite element analysis of unidirectional and cross-ply composite layups through localized microstructures under hygromechanical conditions

Jain

Vats

Bera

et al. 2020

J Braz. Soc. Mech. Sci. Eng.

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Fiber-reinforced polymers (FRPs) are sensitive to moisture diffusion. Deterioration caused by moisture can limit their service lives considerably. In this work, a three-dimensional finite element modeling and analysis framework is presented to investigate the moisture diffusion kinetics inside fiber-reinforced inside polymer matrix composites by considering different angle and cross-ply orientations. A small localized representative volume element considering a few fibers in the neighborhood of three-layer stacks has been analyzed. The emphasis is on the effect of different fiber orientations over moisture saturation time and diffusion-induced stresses. Stresses induced due to moisture diffusion in FRPs are evaluated on the free fiber ends. The numerical results from finite element approximations are compared with theories of composite micromechanics such as rule of mixtures, Halpin-Tsai model and concentric cylinder assemblage framework. It is observed that the orientation of fiber layers can greatly influence the moisture ingress inside the matrix and resulting stresses. At intermediate time durations of moisture progression, the cross-ply orientation had ~ 25% lower weight gain in comparison with the unidirectional ply orientations. The overall von Mises stresses at the fiber matrix interface were also lower in cross-ply orientations by ~ 40% in comparison with the other orientations with similar fiber volume fraction. The three-layered cross-ply, 90/90/90 orientation took almost 50% more time to fully saturate with moisture in comparison with the unidirectional, 0/0/0 orientation. The interpretations from the smaller local microstructural models presented in this work can be extended to study and design the structure scale composite layups for the improved moisture durability.

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“…Positron lifetime spectroscopy (PLS) is a well‐known nondestructive technique and proved to be a very powerful method in direct measurement of free volume sizes in the Å range in polymeric materials, irradiated polymers , polymer blends , composites , and natural polymers . It is also a very powerful technique in detecting the defects in metals and semiconductors .…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of methacrylic acid-based molecular imprinted polymers by positron lifetime spectroscopy

Pasang

Ranganathaiah

2013

Polym Eng Sci

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Three molecular imprinted polymers (MIPs) were prepared with different amounts of crosslinker (ethylene glycol dimethacrylate) in methacrylic acid functional monomer. Positron lifetime spectroscopy has been used to study the variation in free volume cavities (nanosize pores) in these MIPs of different monomercrosslinker ratio. The changes in free volume cavities after the template molecule 4-chlorophenol extracted from the polymer matrix were measured. The results indicate that the optimum monomer-crosslinker ratio for this MIP is 1:5. The free volume distribution derived from CONTIN program further reveals the presence and absence of template molecules in the system. The Fourier transform infrared spectra results have been used to compliment this through the absence of stretching frequencies at 648 cm 21 and 825 cm 21 of CACl suggesting the successful extraction of the template from the MIPs. Scanning electron microscope (SEM) scans indicate the grains are of heterogeneous shape and size in agreement with earlier studies. POLYM. ENG. SCI., 54:667-674, 2014.

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Effect of the fiber orientation on the sorption kinetics of seawater in an epoxy/glass composite: A free‐volume microprobe study

Cited by 4 publications

References 32 publications

A dielectric study of water uptake in epoxy resin systems

A dielectric study of water uptake in epoxy resin systems

A framework for three-dimensional finite element analysis of unidirectional and cross-ply composite layups through localized microstructures under hygromechanical conditions

Synthesis and characterization of methacrylic acid-based molecular imprinted polymers by positron lifetime spectroscopy

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