Factors of hetero space charge generation in XLPE under dc electric field of 20 kV/mm

This report deals with the mechanism of space charge accumulation in cross‐linked polyethylene (XLPE) under dc electric field. Space charge was measured by the pulsed‐electroacoustic method with applying dc stress of 20 kV/mm. A large amount of hetero space charge accumulated in fresh XLPE samples. Factors influencing the space charge accumulation were analyzed in regard to cross‐linking by‐products and antioxidant. No space charge was seen when the fresh sample was degassed to remove cross‐linking by‐products. Introducing acetophenone, one of the cross‐linking by‐products, in a degassed sample produces no space charge, suggesting that acetophenone itself could not be the direct factor of space charge formation. However, heating this sample up to 150 °C results in formation of hetero space charges as in virgin samples. Hence, it is concluded that hetero space charges may be formed when impurities, such as an antioxidant, dissociate thermally with the help of acetophenone and that the dissociated products are attracted toward both electrodes under a dc field to form the hetero space charges. © 1999 Scripta Technica, Electr Eng Jpn, 129(2): 13–21, 1999     

Preparation and properties of ethoxylated fatty methyl ester nonionics

Ehthylene oxide (EO) cannot react directly with fatty methyl esters that have no active hydrogen. We developed a new synthetic method, which directly inserts EO into fatty methyl esters (RCOOCH₃) to give [RCO(OCH₂CH₂)_nOCH₃]. This was achieved by the use of a novel solid catalyst modified by metal cations. Ethoxylates of fatty methyl esters obtained by this method were homogeneous monoesters and had good properties as nonionic surfactants. Presented at the AOCS Annual Meeting & Expo in Anaheim, California, April 1993.     

Breakdown strength at the interface between epoxy resin and silicone rubber-a basic study for the development of all solid insulation

As a key component for a future power substation system entirely consisting of solid insulating materials, a special connection system between different pieces of power equipment has to be developed. A soft dielectric such as silicone rubber and a hard one such as epoxy resin are to be used for this connection. This paper describes the interfacial breakdown strength between silicone rubber and epoxy resin using two types of model samples on which the electric field can be applied in parallel or perpendicularly to their interface. Partial discharge characteristics at the interface and the effect of air penetration on the breakdown voltage along the interface are discussed.     

Determination of a sulfur-containing drug in human plasma by an improved method for sulfur chemiluminescence detection in combination with capillary gas chromatography

An improved method for sulfur chemiluminescence detection in combination with capillary gas chromatography was established. The method was applied to the analysis of a sulfur-containing antiasthma drug, S-1452, and its nine metabolities in human plasma. The high selectivity and sensitivity of the method allowed accurate quantitation of trace levels of these compounds in human plasma with no interferences from the biological components present. To enable stable measurements and maintain reproducibility over a long period, the performance characteristics of a commercially available instrument were investigated. The gas seal in the injection port was found to easily corrode through interaction of the sulfur analyte with the metal gas seal. To prevent this, a disk made from an alloy of platinum and gold (60:40) was mounted on the gas seal. The reproducibility of the measurement was improved remarkably by using the disk. The use of compressed air of high purity significantly lowered the signal-to-noise ratio. The optical filter was kept clean by using a nickel catalyst to trap ozone in place of copper manganese oxide (CuMn2O4). These improvements raised the sensitivity and selectivity with the lower quantitation limits of 0.5-1.0 ng/mL in human plasma.