Electrical Conductivity and Moisture Uptake Studies of Low Density Polyethylene Octylnanosilica Composite

Virtanen, Suvi; Vaughan, A. S.; Yang, Shuangqiao; Saiz, Fernan; Quirke, N.

doi:10.5324/nordis.v0i25.2368

Cited by 6 publications

(6 citation statements)

References 14 publications

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“…The latter appears to be a critical variable and, indeed, elsewhere [34], we have shown that the good dispersion that characterizes systems based upon silicon nitride is actually detrimental, in that exposure to water allows a percolating network of water shells to form. More recent work [42] has shown the same effects in well-dispersed silica systems. Also, from a technological perspective, agglomerates will be present in many bulk prepared commercial nano-powders -such as those used here.…”

Section: Discussionsupporting

confidence: 52%

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

Hosier

Praeger

Vaughan

et al. 2017

IEEE Trans. Dielect. Electr. Insul.

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Particle dispersion, water absorption/desorption and electrical breakdown behavior were studied in a range of polyethylene composites having a common matrix morphology. Three different conditioning routes (dry, ambient and wet) were used to vary the absorbed water content. Systems employing oxide fillers (silica and alumina) were found to have poor or intermediate levels of particle dispersion and could absorb/desorb significant amounts of water. Consequently, they required drying to provide breakdown strengths comparable to that of the host matrix. Systems based on calcined silica exhibited reduced water absorption and provided improved breakdown strength after ambient conditioning, despite having an identical dispersion to those utilizing untreated silica. Composites employing nitride fillers (silicon nitride and aluminum nitride) were found to have good or intermediate levels of particle dispersion. These absorbed far less water and hence provided breakdown strength values comparable to that of the host matrix following ambient conditioning. Their breakdown strength was degraded after wet conditioning with both exhibiting similar breakdown strengths despite there being a large difference in the level of particle dispersion between the two fillers. In composites based upon a hydrophobic host matrix, water absorption is largely determined by particle surface chemistry and, although the above results are presented in terms of water absorption, we suggest that changes in this characteristic can be interpreted as a proxy for changed surface chemistry. The results suggest that surface chemistry is at least as important as particle dispersion in determining the electrical breakdown strength.

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Section: Discussionsupporting

confidence: 52%

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

Hosier

Praeger

Vaughan

et al. 2017

IEEE Trans. Dielect. Electr. Insul.

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show abstract

“…The electrical conductivity of the samples was determined using a system designed and built in-house, which is described in detail elsewhere [20]. In this, the sample was placed between two parallel electrodes, 50 mm in diameter, the required voltage was applied and the resulting current was recorded as a function of time using a Keithley 6487 picoammeter (Keithley Instruments Inc., Cleveland, OH, USA).…”

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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“…The electrical conductivity of the samples was measured using a Keithley 6487 picoammeter. The in-house built apparatus that was used is discussed in detail elsewhere [36]. The dielectric response of the samples was measured using a Solartron 1296 dielectric interface in combination with a Schlumberger SI 1260 impedance/phase gain analyser and a Lake Shore 332 temperature controller.…”

Section: Characterization Techniquesmentioning

confidence: 99%

Understanding the cross-linking reactions in highly oxidized graphene/epoxy nanocomposite systems

et al. 2018

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Graphene oxide (GO) was produced using acidic graphite oxidation and dispersed within an epoxy matrix using a solvent-based technique, to give nanocomposites containing up to 2 wt% of GO. Transmission and scanning electron microscopy revealed a fine dispersion of graphitic sheets which alters the nanocomposite's fractured surface morphology, while Fourier transform infrared spectroscopy revealed an excess of epoxide groups in the system, which are associated with the included GO. These additional moieties react with hardener amine groups and, consequently, displace the reaction stoichiometry away from the optimum. The result of this is a change in the network architecture and, in particular, the introduction of epoxy-terminated branches, which modify the dielectric c relaxation. During post-curing, hydroxyl groups on the GO surface react with residual epoxide groups through etherification reactions, to give a marked increase in the glass transition temperature. These reactions lead to increased interfacial interactions between the GO and the matrix, which contribute to an increase in tensile performance. In addition, post-curing also reduces the defect content within the GO lattice which, in turn, increases the electrical conductivity, dielectric permittivity and low frequency losses of the system. Associated chemical pathways are proposed.

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Electrical Conductivity and Moisture Uptake Studies of Low Density Polyethylene Octylnanosilica Composite

Cited by 6 publications

References 14 publications

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

The effects of hydration on the DC breakdown strength of polyethylene composites employing oxide and nitride fillers

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

Understanding the cross-linking reactions in highly oxidized graphene/epoxy nanocomposite systems

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