Dielectric properties of cured epoxy resin+poly(ethylene oxide) blends

Kalogeras, Ioannis M.; Roussos, Michalis; Christakis, Ioannis; Spanoudaki, Anna; Pietkiewicz, Dorota; Brostow, Witold; Vassilikou‐Dova, Aglaia

doi:10.1016/j.jnoncrysol.2005.03.066

Cited by 21 publications

(14 citation statements)

References 37 publications

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“…Combining the results of this study with those of previous researchers on water uptake in epoxy resins leads to a generalized model for water permeation. Initial moisture absorptionThe first stage is the adsorption of moisture by polar entities in the surface of the resin.…”

Section: Discussionmentioning

confidence: 62%

“…Detailed analysis of the FTIR and nmr spectra have identified singly and doubly hydrogen bonded forms of water which is consistent with the breadth of the dielectric relaxation and the observed values of the Kirkwood “Ng” factor, Table . The activation energy for water diffusion depends on the matrix, but typically has a value between 48 and 60 kJ mol −1 . Plasticization and swellingWater adsorbed at polar sites and in nano‐voids can plasticize the resin and allow changes in topography . PALS measurements have shown changes in the size and number of voids on water absorption .…”

Section: Discussionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

A dielectric study of water uptake in epoxy resin systems

Garden¹,

Pethrick²

2017

J of Applied Polymer Sci

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“…Both the location and strength of the peak recorded above b PEO (e.g., at 20 8C in the homopolymer) is also highly dependent on the selection of the electrode material. [47] Blending induces modifications in the segmental and local-chain dynamics of the constituting phases. The relaxation bands attributed to local-chain motions (g PEO and g ER ) activate in the same temperature region forming a complex band (denoted g blend ), which locates between À190 and À140 8C.…”

Section: Dielectric Characterization Of Cured Er þ Peo Blendsmentioning

confidence: 99%

Thermophysical Properties and Molecular Relaxations in Cured Epoxy Resin + PEO Blends: Observations on Factors Controlling Miscibility

Kalogeras

Vassilikou‐Dova

Christakis

et al. 2006

Macro Chemistry & Physics

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Summary: Thermophysical properties and molecular relaxations in aromatic amine‐cured diglycidyl ether of bisphenol‐A (DGEBA) epoxy oligomer and poly(ethylene oxide) (PEO) mixtures were determined by DSC and dielectric techniques (TSC, DRS). The binary blends were judged to be fully miscible in the amorphous state (wPEO < 40 wt.‐%), as evidenced by the single composition‐dependent glass transition temperatures Tgs. In the amorphous blends, negative deviations of dielectric/thermal Tg‐estimates from the linear mixing rule or the behavior predicted by the Fox equation reveal weaker intermolecular interactions, compared to strong self‐association of hydroxyls in the cured thermoset. Morphological changes in PEO‐rich blends (wPEO ≥ 40 wt.‐%) are in accordance with their complicated interface structure, previously reported to consist of amorphous PEO regions, branched epoxy resin chains and an imperfect epoxy resin network located between PEO lamellae. In these blends, PEO crystallites exert steric hindrances in the amorphous regions, causing strong Tg upshifts. Changes in the relaxation dynamics of glyceryl segments (e.g., in the activation energy barrier and relaxation strength) are in accordance with the idea that the close matching between the molecular polarities of PEO, epoxy resin and the cure agent significantly contributes to the observed miscibility.

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“…Dielectric analysis can be used to monitor changes in characteristics of local relaxations and more importantly to study the variation of the glass transition signal and σ DC at different loadings of the modifi er . 6.32 b) (Kalogeras et al 2005a(Kalogeras et al , 2006b(Kalogeras et al , 2007b. 6.32 a).…”

Section: Evolution Of Relaxation Dynamics During Curementioning

confidence: 99%