摘要:
Compositions comprising: A. Ethylene-based polymer, e.g., LDPE; B. Polyalkylene glycol, e.g., PEG; C. Tertiary hindered amine stabilizer; D. Sulphur-containing hindered phenol antioxidant; E. Peroxide; and F. Optional coagent are useful in the preparation of TRXLPE insulation for medium voltage cable that exhibits a commercially desirable balance of long term heat aging retardancy and water-tree resistance.
摘要:
TRXLPE-type cable sheaths are prepared by a method in which a solid polymer is mixed with a liquid water tree-resistant agent either by dosing or direct injection. In the dosing method, the solid polymer, e.g., high pressure LDPE, is sprayed or otherwise contacted with the liquid agent, e.g., PEG, the agent is allowed to absorb into the polymer, and the polymer with absorbed agent is then fed to an extrusion apparatus for extrusion over a sheathed or unsheathed wire or optic fiber. In the direct injection method, the solid polymer is first fed to an extrusion apparatus, and the liquid agent is sprayed or otherwise contacted with the polymer before the two are blended with one another through the action of the mixing elements of the apparatus.
摘要:
A method for testing a mechanical integrity of an insulating layer covering a conductor in a cable, a longitudinal void being defined inside the insulating layer in a region of the conductor. A first end of the insulating layer is blocked. A compressed gas is injected at a second end of the insulating layer so that the gas enters and travels the longitudinal void inside the insulating layer towards the first end. A gas pressure inside the insulating layer is measured at least near the second end. Injection of the compressed gas is stropped after a predetermined injection time period. A variation of the gas pressure inside the insulating layer is monitored during a diagnostic time window succeeding to a transitional time period following the stopping of the injection. Integrity of the insulating layer is determined based on the variation of the gas pressure during the diagnostic time window.
摘要:
A method for testing a mechanical integrity of an insulating layer covering a conductor in a cable, a longitudinal void being defined inside the insulating layer in a region of the conductor. A first end of the insulating layer is blocked. A compressed gas is injected at a second end of the insulating layer so that the gas enters and travels the longitudinal void inside the insulating layer towards the first end. A gas pressure inside the insulating layer is measured at least near the second end. Injection of the compressed gas is stropped after a predetermined injection time period. A variation of the gas pressure inside the insulating layer is monitored during a diagnostic time window succeeding to a transitional time period following the stopping of the injection. Integrity of the insulating layer is determined based on the variation of the gas pressure during the diagnostic time window.
摘要:
A composition comprising: (i) polyethylene, and, based on 100 parts by weight of component (i), (ii) about 0.3 to about 0.6 part by weight of 4,4′-thiobis(2-methyl-6-t-butylphenol); 4,4′-thiobis(2-t-butyl-5-methylphenol); 2,2′-thiobis(6-t-butyl-4-methylphenol); or a mixture of said compounds, and (iii) about 0.4 to about 1 part by weight of a polyethylene glycol having a molecular weight in the range of about 1000 to about 100,000.
摘要:
A process for crosslinking comprising (a) introducing into a reactor, under crosslinking conditions, a mixture comprising(i) one or more polyolefins;(ii) organic peroxide;(iii) an ester, ether, or ketone containing two or more unsaturated groups; and(iv) a compound having the formula: ##STR1## wherein R=hydrogen, methyl, or ethyl; R.sup.1 =an alkylene having 1 to 6 carbon atoms;andR.sup.2 =an alkyl having 8 or more carbon atoms or Si(R.sup.3).sub.3 wherein R.sup.3 is hydrogen or alkoxy having 1 to 6 carbon atoms; each R.sup.3 is the same or different; and at least one R.sup.3 is an alkoxy,and (b) crosslinking the polyolefin(s).
摘要:
The method of manufacturing a natural ester, oil-based electrical insulation fluid by contacting refined, bleached, optionally winterized, and deodorized natural ester oil, e.g., soy oil, with an absorbent is improved by using as the absorbent a synthetic silicate absorbent comprising an alkali and/or alkaline earth metal, e.g., magnesium.
摘要:
Compositions comprising: A. Ethylene-based polymer, e.g., LDPE; B. Polyalkylene glycol, e.g., PEG; C. Tertiary hindered amine stabilizer; D. Sulphur-containing hindered phenol antioxidant; E. Peroxide; and F. Optional coagent are useful in the preparation of TRXLPE insulation for medium voltage cable that exhibits a commercially desirable balance of long term heat aging retardancy and water-tree resistance.
摘要:
Power cables that comprise a sheath layer, e.g., an insulation layer, are produced from a mixture of a high pressure polyolefin free of silane functionality, e.g., high pressure low density polyethylene, and a polyether polyol of which at least 50 percent of its molecules comprise no more than a single hydroxyl functionality. Preferably, the power cable is a medium or high voltage power cable, and the polyolefin is crosslinked as the sheath layer is fabricated and/or subsequent to the fabrication of the sheath layer.
摘要:
A process for the co-extrusion of an inner layer around a conductive medium and an outer layer around the inner layer including:(i) introducing into an extruder adapted for profile coextrusion, a preformed conductive medium; an inner layer formulation including a homogeneous polyethylene having a polydispersity in the range of about 1.5 to about 3.5 and an essentially uniform comonomer distribution, and an organic peroxide; and an outer layer formulation including (A) one of (a) a copolymer of ethylene and an unsaturated ester; (b) or a polyethylene having a polydispersity greater than about 4.0 and a density of at least 0.916 gram per cubic centimeter, said polymer made by a high pressure process; or (c) a heterogeneous copolymer of ethylene and one or more alpha-olefins having a density of less than 0.916 gram per cubic centimeter, a melt index of at least about 4 grams per 10 minutes, and a polydispersity greater than about 4.0, and, (B) optionally, an organic peroxide; and(ii) co-extruding said formulations around the conductive medium at a temperature no higher than about 160 degrees C.