C.L. Mirley's research while affiliated with University of Connecticut and other places

Publications (6)

Article
The silicone-based coating applied to 345 kV post insulators in a substation on the shore of Long Island Sound has depolymerized over a period of about 7 years although no in-service failures have occurred. However, the increasing rate of depolymerization suggests that the coatings will have to be renewed in the near future. This paper reports comp...
Article
Analysis using gas chromatography/mass spectroscopy (GC/MS) was performed for evaluation of surface degradation of silicone insulating materials. Silicones are used as coatings for porcelain insulators and shed material for high voltage composite insulators. A comparison between virgin silicone rubber and aged silicone rubber samples, which were ag...
Article
Silicone-based materials for outdoor insulators have the advantage that low molecular weight (LMW) components migrate through the material and coat the surface, thereby restoring hydrophobicity over a period of hours. By measuring the IR absorption of siloxane migrating to the silicone surface through a thin carbon coating, the time constant for mi...
Conference Paper
Thermogravimetric analysis (TGA) was used to evaluate the surface degradation of polymer insulators designed for outdoor high voltage applications. Such insulators are usually formed as a composite of silicone matrix and inorganic materials, such as aluminum trihydrate (ATH) filler and/or fumed silica. However, the surface of insulators is subject...
Conference Paper
Silicone-based materials for outdoor insulators have the advantage that low molecular weight (LMW) components migrate through the material and coat the surface, thereby restoring hydrophobicity over a period of hours. By measuring the infrared (IR) absorption of siloxane migrating to the silicone surface through a thin carbon coating, the aspect of...
Conference Paper
The present contribution describes an analytical technique which can be used to investigate degradation phenomena of silicones and provide a quantitative evaluation of surface degradation. The technique employed in the present investigation is based on the use of gas chromatography/mass spectrometer (GC/MS) methods

Citations

... For all samples, the TGA curves obtained their weight loss at a temperature of 500˚C tended to decrease of 89% for the virgin sample, 79% for the samples after ageing 60 h and 70% for the samples after ageing 120 h. This result indicates that the weight loss of the samples after the accelerated ageing process was slightly higher than the virgin sample, according to comparison of TGA curves for the virgin and aged silicone rubber material caused by depolymerisation of the siloxane matrix during the ageing process [245]. The weight loss rate of silicone elastomer can be divided into three main phases of temperature, which consisted of the low molecular weight silicone at 310˚C, the maximum weight loss due to decomposition of the crosslinked silicone elastomer at 450˚C and the formation of the silica glass, including loss of carbon on the bulk of molecular structures between 630˚C and 670˚C [246]. ...
... A FTER about 7 years of aging at the Millstone NGS on the Connecticut coast, the RTV silicone coatings on station post insulators have depolymerized substantially resulting in conversion of low molecular weight (LMW) PDMS ( to 15 DMS units) to to 5 units, which are of such low molecular weight that they are volatile and much more easily washed off the surface (Fig. 1).Fig. 2 shows the mass spectrum of LMW PDMS components with 3, 4, and 5 PDMS units which indicate that these components are primarily cyclic in nature [1]. The recent measurements in [2] confirm this finding. ...
... In Figure 2a, two parameters are presented: mass rise after the swelling process, which is proportional to the number of bonds created between different macromolecules, and mass loss during the swelling process, which is proportional to the amount of low molecular weight particles washed out in the swollen state [52]. Thus, it may be concluded that δ-TF and QU did not affect cross-linking density in a significant way as the samples are swollen similarly to the reference ENR/PLA blend. ...
... In order for a surface to be superhydrophobic, it should have a water contact angle of 150 • or greater [6,7]. Silicone rubber (SR) as a polymer has a high hydrophobicity due to an inorganic backbone of Si-O that attaches to the organic groups (frequently methyl) [8][9][10][11]. SR is commonly used in many fields such as fabrication of electrical insulators [12], biomedicine, machinery, electronics and food processing [13] due to its excellent resistance, low toxicity [14], super transparency, high thermal stability [15], and hydrophobicity. ...
... There have been many studies on the engineering applications of silicone rubber coating in electrical power systems, which have provided many theoretical bases for the engineering applications of silicone rubber coatings [2][3][4][5][6][7][8][9][10]. However, research on the characteristics of the partial discharge on the surfaces of silicone rubber coatings is rare. ...
... Here, the m/z of 73, 147 and 221 correspond to the structure of [+Si(CH 3 ) 3 ], [+(CH 3 ) 2 SiOSi(CH 3 ) 3 ], and [+((CH 3 ) 2 SiO) 2 Si(CH 3 ) 3 ], which originate from the methyl shift process after the electron impact. By contrast, the m/z of 207, 281 results from the loss of a methyl group (CH 3 ) in D 3 and D 4 , respectively [19]. The results indicate that peaks from N-1 to N-19 are also siloxanes, judging by the distinctive mass number, that is, m/z of 73, 147, 207, 221 and 281. ...