Electrical strength and chemical surface analysis of polypropylene after exposure to external partial discharges

Rodehed, Cenita; Gustafsson, Åsa B.; Gedde, Ulf W.

doi:10.1109/14.64491

Cited by 17 publications

(4 citation statements)

References 14 publications

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“…The five-layer laminar composite consisting of sheets of PS-SEBS-PE-SEBS-PS exhibited electrical properties superior to those predicted by the upper bound rule of mixing. In a previous paper (22) it was reported that external PD on polypropylene caused a considerable surface roughening and that breakdown occurred when the surface cracks reached a critical depth of the order of 40 to 50 pm. The presence of a more stable surface layer of a thickness such as that of the PS sheets in the laminar composites may well give rise to the observed increase in PD strength.…”

Section: Discussionmentioning

confidence: 99%

Electrical degradation of blends and laminar composites of polyethylene and polystyrene

1993

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Physical blends and laminar composites of polystyrene (PS) and polyethylene (PE) were prepared with and without a tri‐block copolymer compatibilizer (poly(styrene‐block‐(ethylene‐co‐1‐butene)‐block‐styrene)), denoted SEBS. Dielectric strength and breakdown time of samples exposed to external partial discharges (PD) were measured and relationships were sought with composition, phase morphology, and phase bonding. The polymers were selected because they are incompatible and because the dielectric strength and stability towards PD are greater for PS than for PE. It was shown by adding small quantities of SEBS that a minimum amount of cohesive forces between the components was required to achieve good electrical properties. The major morphological factor controlling the electrical stability was which polymer constituted the continuous phase. Laminar composites with continuous sheets of stable PS as a top layer exhibited a stability equal to or better than that predicted from the upper bound rule of mixing.

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Section: Discussionmentioning

confidence: 99%

Electrical degradation of blends and laminar composites of polyethylene and polystyrene

1993

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“…Presence of molecular oxygen results in the formation of water, alcohols, and carbonyl groups (aldehydes, ketones, carboxylic acids, etc.) [29,30]. This process is known as auto-oxidation and arises from the paramagnetic nature of molecular oxygen, as its ground state contains two unpaired electrons that are very reactive with the unpaired electron of a free radical.…”

Section: Technical Backgroundmentioning

confidence: 99%

The effect of oxidative and paper degradation impurities on partial discharge characteristics of hexadecane

Bolliger

Pilania

Boggs

2013

IEEE Trans. Dielect. Electr. Insul.

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Partial discharge (PD) characteristics of hexadecane were studied in a needle-plane electrode geometry under AC field with a tungsten needle of 20 m tip radius. PD experiments were conducted on samples containing known concentrations of oil/paper degradation compounds. Partial discharge inception voltage (PDIV), streamer repetition rates, and phase resolved PD (PRPD) patterns were acquired. Ionization potentials (IP) and electron affinities (EA) of hexadecane and a selection of additives were calculated with density functional theory (DFT) and correlated to PD characteristics. IP did not have a significant effect on the number of streamers initiated as most additives had higher IP relative to hexadecane. The presence of electronegative oxygen changes substantially the PD characteristics and, for most additives, increases the number of positive and negative streamers initiated. The greatest changes in PD characteristics, a reduced number of negative streamers, was observed for compounds with large electron capture cross section, even those with negative EA.

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“…Degradation leads to the formation of various volatile products, and in some cases crosslinking may occur. The surface is roughened and ultimately, when a critical surface roughness is attained, final breakdown of the film occurs (19). I t can be stated that the overall stability of a given polymer sample is controlled by several factors: (a) the state of the cold plasma (constant in this study): (b) the stability of the polymer towards the formation of the primary radicals; (c) the segmental mobility: (d) the stability of the polymer towards the formation of secondary radicals (depolymerization and crosslinking).…”

Section: Molar Content Of P-phs In Copolymermentioning

confidence: 99%

Electrical degradation of homo‐ and copolymers of styrenes and of styrene/2‐vinylnaphthalene

Gustafsson

Wiberg

Gedde

1993

Polymer Engineering & Sci

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A variety of different styrene monomers [styrene (S), p‐fluorostyrene (p‐FS), pentafluorostyrene (PFS), p‐chlorostyrene (p‐ClS), p‐bromostyrene (p‐BrS), p‐methylstyrene (p‐MS), p‐tert‐butylstyrene (p‐tBS), p‐methoxystyrene (p‐MOS), p‐ethoxystyrene (p‐EOS), and p‐propoxystyrene (p‐POS)] have been polymerized by radical and cationic mechanisms. Copolymers of S/PFS, S/p‐ClS, S/2‐vinyl‐naphthalene (2‐VN), and S/p‐phenylstyrene (p‐PhS) were prepared by radical polymerization. All polymers were fully amorphous and transparent and exhibited only one glass transition temperature in the temperature range 77 to 141°C. Thin films of the polymers were subjected to external electrical partial discharges (PD). Typically, 20 PD experiments were conducted for each polymer and the data for the time to breakdown were adapted to the two‐parameter Weibull distribution function. The resistance towards PD of the various polymers was found to depend strongly on the monomeric structure. Complementary PD experiments on a series of narrow molecular mass polystyrenes confirmed that the minor variation in molecular mass between the different styrene polymers is of no importance for the PD resistance. The PD resistance of the homopolymers decreased in the following order: PS ≈︁ P(p‐MS) > P(p‐tBS) ≈︁ P(p‐BrS) > P(p‐POS) > P(p‐ClS) ≈︁ P(p‐MOS) > P(p‐EOS) ≈︁ P(p‐FS) > P(PFS). The time to breakdown for copolymers of S and PFS decreased monotonously with increasing PFS content. Styrene copolymers with low molar contents of 2‐ VN and p‐PhS exhibited a higher resistance towards PD than PS. The results are discussed with reference to various properties of the studied polymers, such as segmental mobility, ionization potential, resonance stabilization, and reactivity of the radicals formed.

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Electrical strength and chemical surface analysis of polypropylene after exposure to external partial discharges

Cited by 17 publications

References 14 publications

Electrical degradation of blends and laminar composites of polyethylene and polystyrene

Electrical degradation of blends and laminar composites of polyethylene and polystyrene

The effect of oxidative and paper degradation impurities on partial discharge characteristics of hexadecane

Electrical degradation of homo‐ and copolymers of styrenes and of styrene/2‐vinylnaphthalene

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