On the dielectric response of silica-based polyethylene nanocomposites

Lau, Kwan Yiew; Vaughan, A. S.; Chen, G; Hosier, I. L.; Holt, A. F.

doi:10.1088/0022-3727/46/9/095303

Cited by 92 publications

(123 citation statements)

References 21 publications

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“…Under such conditions, silanol production and subsequent reaction are expected to be confined to the vicinity of nanosilica surfaces containing hydroxyl groups/adsorbed water. Detailed information on the surface modification process and the mechanisms involved can be found elsewhere [43,45]. This surface modified nanosilica is referred to as C3-treated nanosilica throughout the text.…”

Section: Methodsmentioning

confidence: 99%

“…An in-depth discussion of nanoparticle dispersion and matrix morphology is not the primary emphasis here, since this has been covered elsewhere [43,45]. Nevertheless, in summary, in all the nanocomposites, a significant mass fraction of the nanofiller appeared in the form of agglomerates, which were not easily broken up and dispersed even after surface…”

Section: Dispersion and Morphologymentioning

confidence: 99%

“…Nanocomposite samples were prepared using a solution blending method, as described in detail elsewhere [43,45]. Briefly, the desired amount of nanosilica (2 wt%, 5 wt% or 10 wt%) was sonicated in xylene before the polyethylenes were added.…”

Section: Sample Preparationmentioning

confidence: 99%

“…This work revealed the existence of localized states at the interface that the authors associated with double bond in the vinylsilane and classified these as shallow traps for electrons and holes, due to their proximity to the conduction band and valence band edges. Evidently, the electrical response of nanoparticle interfaces is subtly dependent on such factors, which are deliberately introduced, and on the diffusion of mobile species to interfaces [43] and, consequently, the detailed study of the local structure, chemistry and electrical characteristics of such regions is in its infancy. However, since the concept of dielectric nanocomposites was first introduced by Lewis in 1994 [17], the essential characteristics of this class of material have been associated with variations in the "intensity" I [5] of properties associated with local interfacial features, such that the extent of the interface/interphase is then defined by the local spatial variation in I.…”

Section: Introductionmentioning

confidence: 99%

“…Detailed information on the surface modification process and the mechanisms involved can be found elsewhere [43,45]. This surface modified nanosilica is referred to as C3-treated nanosilica throughout the text. …”

mentioning

confidence: 99%

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Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Lau

Vaughan

Chen

et al. 2016

J. Phys. D: Appl. Phys.

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The topic of nanodielectrics continues to receive significant attention from today's dielectrics community, due to the property enhancements that can stem from the unique interfacial features within such material systems. Nevertheless, understanding of the interfacial phenomena that occur in nanodielectrics and which determine their electrical behaviour is challenging. In this paper, we report on an investigation into the absorption current behaviour of two nanocomposite systems, one containing an untreated nanosilica and the other containing the same nanofiller chemically modified using trimethoxy(propyl)silane.The results indicate that the absorption current behaviour of all the nanocomposites is very different from that of the reference, unfilled polymer; while the current flowing through the unfilled polyethylene decreased monotonically with time in a conventional manner, all nanocomposites revealed an initial decrease followed by a period in which the current increased with increasing time of electric field application. Possible mechanisms leading to the observed absorption current behaviour in the nanocomposites are discussed with the aid of space charge measurements. The presence of space charge limited conduction (SCLC) and its trap-filled limit is proposed.Keywords: nanocomposites, nanosilica, interface, absorption current, space charge limited conduction. 2 IntroductionThe addition of a nanofiller to a polymer matrix has been shown to be a flexible means of tailoring the dielectric properties of materials [1][2][3] and Chen et al. [19], for example, have emphasized the unsatisfactory nature of our understanding of charge transport mechanisms. In conventional polymeric insulation, charge transport mechanisms are extremely complicated, when compared with many conducting and semiconducting materials [20,21]. In semicrystalline polyethylene, for example, chainfolded lamellar crystals are surrounded by amorphous conformations and there is likely to be a high concentration of traps relating to each of these structural motifs. On the addition of a nanofiller, charge transport mechanisms will become yet more complicated, since the inclusion of nanoparticles will introduce extensive interfacial surfaces between the nanofiller and the polymer. The presence of such interfaces may directly introduce additional nanofiller/polymer trapping sites and/or modify the surrounding polymer morphology, thereby affecting the local density of states within the system.The current flow caused by the action of an applied electric field on charge carriers within a dielectric material can broadly be categorized into three types [22]: the initial current that flows through the material is the capacitive charging current, which causes a dramatic rise at the very beginning of the voltage application. This is followed by a gradual decrease of current, known as the absorption current or the anomalous current. Conventionally, the absorption current decreases slowly until it reaches a quasi-steady state, providing a conduction c...

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Section: Methodsmentioning

confidence: 99%

Section: Dispersion and Morphologymentioning

confidence: 99%

Section: Sample Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Lau

Vaughan

Chen

et al. 2016

J. Phys. D: Appl. Phys.

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Sulfonated gamma‐irradiated blend poly(styrene/ethylene‐vinyl acetate) membrane and their electrical properties

Ghobashy

Khozemey

2016

Adv Polym Technol

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A compatibilized blend membrane of polystyrene (PS)/polyethylene-vinyl acetate (PEVA) (50: 50) wt % was produced by compression molded at 180°C after irradiated by gamma ray at 50-kGy dose. The influence of gamma radiation on the properties of the blend (PS/PEVA) membrane was investigated. The irradiated samples showed an increase in the degree of crystallinity due to the presence of additional chemical bonds as observed by X-ray diffraction. As a result of irradiation, the miscibility of the two polymer matrix is enhanced by interfacial adhesion between the components in the blend polymer without any voids as observed by scanning electron microscopy. Furthermore, electrical conductivity in the blend (PS/PEVA) membrane was enhanced by introducing SO 3 H groups. Sulfonation process converts the blend from noncontact (5 × 10 −8 S cm −1 ) to semi-contact (3.8 × 10 −3 S cm −1 ) by AC current at wet condition, and this can find applications in the fuel cells. K E Y W O R D Scompatibilization, electrical conductivity, gamma irradiation, morphology, PS/EVA blends

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Effect of the compatibility on dielectric performance and breakdown strength of poly(vinylidene fluoride)/low‐density polyethylene blends

Lin

Fan

Zhao

et al. 2015

J of Applied Polymer Sci

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Immiscible polymer blends with high dielectric constant (e) and improved breakdown strength (E b ) performance were obtained by composing poly(vinylidene fluoride) (PVDF) with low-density polyethylene (LDPE) or the LDPE grafted with maleic anhydride (LDPE-g-MAH) through melt-blending way. The dielectric properties of these blends were emphasized for considering the compatibility effect on the energy storage application. Interface morphology, co-continuity behavior, and grafted ratio were simultaneously investigated to detect the compatibility enhancement after introducing MAH. Results showed that the MAH positively improved the dielectric properties. Both the measured E b of PVDF/LDPE and PVDF/LDPE-g-MAH blends showed a minimum value at v PVDF 5 50 vol % because of the worst compatibility; meanwhile, higher E b of PVDF/LDPE-g-MAH than that of PVDF/LDPE blend was observed owing to the better compatibility. For considering the effect interface morphology on the dielectric performance, layerstructure films composing with pure PVDF and LDPE layers were further constructed and studied. It was revealed that the layered structure could be treated as a helpful way to improve e and E b for immiscible polymer blends.

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On the dielectric response of silica-based polyethylene nanocomposites

Cited by 92 publications

References 21 publications

Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Polyethylene/silica nanocomposites: absorption current and the interpretation of SCLC

Sulfonated gamma‐irradiated blend poly(styrene/ethylene‐vinyl acetate) membrane and their electrical properties

Effect of the compatibility on dielectric performance and breakdown strength of poly(vinylidene fluoride)/low‐density polyethylene blends

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