The effect of curing conditions on the electrical properties of an epoxy resin

Saeedi, Istebreq A.; Vaughan, A. S.; Andritsch, Thomas; Virtanen, Suvi

doi:10.1109/ceidp.2016.7785649

Cited by 22 publications

(6 citation statements)

References 5 publications

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“…Following degassing, samples of the required thickness were cast in pre-assembled steel molds, which were then placed in a fan oven for curing. The amine hardened samples were cured at 80 °C for 2 h, then post-cured at 125 °C for 3 h, based upon a prior detailed study [16]. The anhydride-hardened systems were cured, initially at 90 °C for 2 h, then at 150 °C for 4 h, as recommended by the manufacturer.…”

Section: Methodsmentioning

confidence: 99%

On the Dielectric Behavior of Amine and Anhydride Cured Epoxy Resins Modified Using Multi-Terminal Epoxy Functional Network Modifier

2019

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A range of modified amine- and anhydride-cured epoxy systems based upon diglycidyl ether of bisphenol A was produced, through the systematic incorporation of moieties termed functional network modifiers (FNMs) that serve to change the network structure in controlled ways. Here, the chosen FNM was trimethylolpropane triglycidyl ether (TTE). The resulting materials were characterized by Fourier transform infrared spectroscopy, thermal analysis, dielectric spectroscopy and measurements of direct current conduction. A progressive reduction in the glass transition temperature of the modified samples was seen with increasing TTE, which is interpreted in terms of changes in the network architecture of the resin. The molecular origins of the dielectric and relaxation processes are proposed. The observed increase in conduction seen exclusively with increasing TTE content in the amine-cured systems is considered in terms of the chemistry of the FNMs, variations in free volume, changes in molecular dynamics and residual unreacted groups retained from the curing reaction. Specifically, we relate the observed increase in conduction to the presence of unreacted amine groups.

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Section: Methodsmentioning

confidence: 99%

On the Dielectric Behavior of Amine and Anhydride Cured Epoxy Resins Modified Using Multi-Terminal Epoxy Functional Network Modifier

2019

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“…The curing and post-curing processes used here were determined from a detailed optimisation investigation reported elsewhere. 26 The produced samples, nominally 200 m in thickness, were stored in vacuum until use.…”

Section: Materials and Sample Preparationmentioning

confidence: 99%

Functional design of epoxy-based networks: tailoring advanced dielectrics for next-generation energy systems

Saeedi¹,

Vaughan²,

Andritsch³

2019

J. Phys. D: Appl. Phys.

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Epoxy resins are widely used as the primary insulation material in many demanding energyrelated applications. As such, the ability specifically to tailor the electrical performance of such systems to meet increasingly demanding insulation situations has considerable utility. This paper describes a new approach to this problem, which is based upon the controlled introduction of specific functional groups into the cured resin's network architecture. Here, two additives are considered, termed functional network modifiers (FNM), namely glycidyl hexadecyl ether and glycidyl 4-nonylphenyl ether; in all the investigated systems, the ideal stoichiometric ratio of epoxide groups to amine hydrogens is retained. In the case of both FNM, their inclusion resulted in a progressive reduction in the glass transition temperature T g of the system, a reduction in the real part of the permittivity and reduced dielectric losses wihin the accessible frequency range, increased DC conductivity and increased AC breakdown strength. The magnitude of the observed effects are found to be dependent upon the choice of functional modifier, which suggests that such changes are not related merely to the inclusion of an additive within the system, but are also influenced by the chemistry of the additive itself. Explanations for these effects are proposed. It is concluded that the use of such FNM at low concentrations (~4% in the work reported here) offers a novel alternative means of engineering advanced materials to meet the current and future needs in an adaptable and easily implemented manner.

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“…Epoxide resins are among the most commonly used polymer-based insulating adhesives in high-voltage insulations [ 1 , 2 ]. These epoxy resins can be cured by anhydrides or amines after thermal activation.…”

Section: Introductionmentioning

confidence: 99%

Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites

et al. 2017

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Five types of nanofillers, namely, silica, surface-silylated silica, alumina, surface-silylated alumina, and boron nitride, were tested in this study. Nanocomposites composed of an epoxy/amine resin and one of the five types of nanoparticles were tested as dielectrics with a focus on (i) the surface functionalization of the nanoparticles and (ii) the water absorption by the materials. The dispersability of the nanoparticles in the resin correlated with the composition (OH content) of their surfaces. The interfacial polarization of the thoroughly dried samples was found to increase at lowered frequencies and increased temperatures. The β relaxation, unlike the interfacial polarization, was not significantly increased at elevated temperatures (below the glass-transition temperature). Upon the absorption of water under ambient conditions, the interfacial polarization increased significantly, and the insulating properties decreased or even deteriorated. This effect was most pronounced in the nanocomposite containing silica, and occurred as well in the nanocomposites containing silylated silica or non-functionalized alumina. The alternating current (AC) breakdown strength of all specimens was in the range of 30 to 35 kV·mm −1 . In direct current (DC) breakdown tests, the epoxy resin exhibited the lowest strength of 110 kV·mm −1 ; the nanocomposite containing surface-silylated alumina had a strength of 170 kV·mm −1 . In summary, water absorption had the most relevant impact on the dielectric properties of nanocomposites containing nanoparticles, the surfaces of which interacted with the water molecules. Nanocomposites containing silylated alumina particles or boron nitride showed the best dielectric properties in this study.

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The effect of curing conditions on the electrical properties of an epoxy resin

Cited by 22 publications

References 5 publications

On the Dielectric Behavior of Amine and Anhydride Cured Epoxy Resins Modified Using Multi-Terminal Epoxy Functional Network Modifier

On the Dielectric Behavior of Amine and Anhydride Cured Epoxy Resins Modified Using Multi-Terminal Epoxy Functional Network Modifier

Functional design of epoxy-based networks: tailoring advanced dielectrics for next-generation energy systems

Effect of Interfacial Polarization and Water Absorption on the Dielectric Properties of Epoxy-Nanocomposites

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