LMW components in silicone rubbers and epoxy resins

Janssen, Henrike; Herden, A.; Karner, H.C.

doi:10.1049/cp:19990782

Cited by 18 publications

(5 citation statements)

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“…The plates were washed with acetone. Subsequently, an artificial pollution layer of 0.5 mm silica W12 was applied to the surface according to [5]. The behavior of a 30ml droplet of water was investigated several times after the application of the silica layer, according to Table III.…”

Section: Methodsmentioning

confidence: 99%

Experiences with new hydrophobic cycloaliphatic epoxy outdoor insulation systems

Beisele¹,

Kultzow²

2001

IEEE Electr. Insul. Mag.

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C ycloaliphatic epoxy resins (CEP) have been used successfully alongside silicones and ceramics (porcelain, glass) for more than 30 years as insulation materials for outdoor applications [1].Insulators made of cycloaliphatic epoxies offer many advantages over those made of ceramic or silicones. Due to their rubbery nature, silicones cannot be used as construction materials, although they have impressive hydrophobic properties. Therefore, silicones are only used as housing materials in combination with reinforcement (e.g., glass fiber rod for composite insulators). Conversely, standard CEPs are construction materials; however, they do not exhibit hydrophobicity as do silicones. This gap has been filled with a new generation of cycloaliphatic epoxy systems with enhanced hydrophobic properties [2] which are referred in the following as HCEP (Hydrophobic Cycloaliphatic Epoxy). These are now commercially available. Compared to standard cycloaliphatic epoxies, HCEP offers three main advantages: G HCEP shows a hydrophobicity transfer effect (Fig. 1). This is the ability to convert a hydrophilic pollution precipitated on a surface to a hydrophobic state. G HCEP shows a hydrophobicity recovery effect (Fig. 2). This is the ability to regain the initial hydrophobicity after a temporary forced loss (e.g., due to electrical discharges). G HCEP shows greatly improved thermal cycle crack resistance. Due to its unique composition, less stress is produced in case of temperature changes despite mismatches of coefficients of thermal expansion to metallic inserts. This was demonstrated by a very demanding thermal cycle crack test (result illustrated in Fig. 3, details to be found in [2], [3]. This very advantageous property is usually only achieved with core shell toughening technology, as described in [4]. Hydrophobicity prevents formation of completely saturated (and, therefore, resistive-conductive) zones on an insulator's surface. This helps to reduce discharging activity and decreases the probability of flashover. Improved hydrophobicity is especially required for medium-voltage outdoor electrical applications that operate in heavily polluted areas, where silicone-based composite insulators are usually employed.In this paper, HCEP and a prefilled product based thereon are described more in detail and an update of new test results is given.

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Section: Methodsmentioning

confidence: 99%

Experiences with new hydrophobic cycloaliphatic epoxy outdoor insulation systems

Beisele¹,

Kultzow²

2001

IEEE Electr. Insul. Mag.

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“…In the present work, about 14.7% increase in average pore fused more rapidly to the bulk. 61 As the temperature increases, thermal activation occurs in the system. As a result, the system gains energy at a rate proportional to $k B T (where k B is the Boltzmann constant and T is the temperature in Kelvin).…”

Section: Hydrophilicity Enhancement By Plasma Treatmentmentioning

confidence: 99%

Flux enhancement of cellulose nitrate membrane through plasma assisted route for waste and mud water treatment

Hazarika,

Das,

Jose

et al. 2023

Polymers for Advanced Techs

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Fouling of polymeric membranes is a common problem due to its hydrophobic nature. Plasma assisted surface modification of polymeric membranes are immensely popular method in particular for the improvement of antifouling and adhesive properties. The effect of low‐pressure nitrogen plasma on surface morphology, hydrophilicity, structure, permeate flux and ageing effect for the cellulose nitrate polymer membrane are studied in the present work. The cylindrical Langmuir probe and optical emission spectroscopy are used to characterize the plasma. The macro void creation and pore enlargement effects have been observed from scanning electron microscopy images due to the surface etching of the membrane after plasma treatment. The atomic force microscopy analysis shows a prominent enhancement of the surface roughness of the plasma treated membrane. Wettability of membrane is studied as a function of plasma treatment time for treated and untreated membrane. From the contact angle measurement, it is found that the hydrophilicity of the plasma treated membranes increases with plasma treatment time. From gravity filtration process, the enhancement of permeate flux for both waste water and mud water are observed after plasma treatment. The ageing mechanism of the treated membranes is investigated for 30 days for different plasma treatment time. The hydrophobic recovery of plasma treated membranes is significant for initial ageing period of 7 days, after that it has shown almost stable in nature. A theoretical model is developed to study the hydrophilic recovery of plasma treated membranes. It is observed that the experimental results show a very good agreement with the theoretical results.

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“…These LMW siloxanes are initially formed during the polymerization process of silicone rubber. The aging of silicone rubber could either prevent the hydrophobicity recovery by the decomposition of LMW siloxanes and the crosslinking reactions or facilitate the recovery process through generation of LMWs from the scission of long backbone chains [54,55]. In most studies [56][57][58], it has been shown that when a silicone rubber surface is covered with a non-hydrophobic contamination layer operating in a highly contaminated environment, the uncrosslinked LMW components move to the surface and penetrated into the contaminants, thereby varying the contamination layer from hydrophilic to hydrophobic.…”

Section: Effect Of Electrical and Environmental Stresses On Self-heal...mentioning

confidence: 99%

Self-Healing Silicones for Outdoor High Voltage Insulation: Mechanism, Applications and Measurements

et al. 2022

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This paper discusses the state of the art in the application of self-healing silicone-based materials for outdoor high-voltage insulation. Both the dynamic behavior of the dimethyl side groups of silicone rubber and the diffusion of a bulk siloxane to maintain low surface energy are respectively reported as intrinsic mechanisms responsible for the self-healing of silicone rubber. Localization, temporality, mobility, and the type of synthesis are the aspects defining the efficiency of the self-healing ability of silicone rubber. In addition, the deterioration of the self-healing ability with filler loaded into silicone rubber insulation housing composites is discussed. Taking the self-healing property into consideration among the other properties of silicone rubber insulators, such as tracking and erosion resistance, can be a useful design practice at the material development stage. Hydrophobicity retention, recovery, and transfer measurements are discussed as useful indicators of the self-healing ability of silicone rubber. Nevertheless, there remains a need to standardize them as design tests at the material development stage. The paper is intended to shed the light on the hydrophobicity recovery, a key material design parameter in the development of silicone rubber outdoor insulating composites, similar to the tracking and erosion resistance.

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LMW components in silicone rubbers and epoxy resins

Cited by 18 publications

References 0 publications

Experiences with new hydrophobic cycloaliphatic epoxy outdoor insulation systems

Experiences with new hydrophobic cycloaliphatic epoxy outdoor insulation systems

Flux enhancement of cellulose nitrate membrane through plasma assisted route for waste and mud water treatment

Self-Healing Silicones for Outdoor High Voltage Insulation: Mechanism, Applications and Measurements

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