江蘇春晨電纜有限公司：http://www.caria-chile.com/st82365/
FDEG風(fēng)能電纜，江蘇春晨電纜有限公司專業(yè)生產(chǎn)FDEG風(fēng)能電纜，F(xiàn)DEG-40(-55) 0.6/1kV1.8/3kV銅芯乙丙橡皮絕緣硅橡膠橡皮護(hù)套風(fēng)力發(fā)電用耐寒(耐嚴(yán)寒)耐扭曲軟電纜。
Polyethylene of plastic for cable
Synthetic methods and varieties of polyethylene
(1) low density polyethylene (LDPE)
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A small amount of oxygen or peroxide is added to the pure ethylene for the initiator, compressed to 202.6kPa, and heated to about 200oC, the ethylene on the synthesis of white waxy polyethylene. This method is under high pressure, often referred to as the high pressure method. With this method, the soft polyethylene with a density of 0.930 ~ 0.915 can be obtained with a molecular weight of 15000 to 40000. The molecular structure of the branched chain is more, but the structure is loose, and the molecular configuration is "dendritic", so the density is low, so it is called low density polyethylene.
(2) medium density polyethylene (MDPE)
In 30 ~ 100 atmospheric pressure, using metal oxide as catalyst, the ethylene polymerization into polyethylene method, known as the medium pressure method. The density of polyethylene is 0.931 ~ 0.940. Medium density polyethylene is also useful for the incorporation of high density polyethylene and low density polyethylene; or a medium density polyethylene, which is formed by the copolymerization of ethylene with maleic, vinyl acetate and acrylic acid.
(3) high density polyethylene (HDPE)
At room temperature and atmospheric pressure, the high catalytic efficiency of the complex catalyst (with aluminum chloride and four titanium chloride compound organic compounds), so that the ethylene polymerization into polyethylene. Because of its high catalytic performance, so the polymerization of ethylene can be at a lower pressure or lower temperature (0 ~ 10 atmospheric pressure and 60 ~ 75oC very fast complete, called the low pressure method. The molecular structure of PE has no branching characteristics, and its molecular structure is linear. Linear molecular structure has the characteristics of high density (0.965 ~ 0.941), called high density polyethylene. Compared with low density polyethylene, it has the advantages of heat resistance, good mechanical performance and good resistance to environmental stress cracking.
Properties of polyethylene
Polyethylene is a milky white plastic, the surface is waxy and translucent, is the ideal insulation and sheath material wire and cable. The main advantage is that:
(1) excellent electrical performance. The insulation resistance and dielectric strength is high; in a wide frequency range, the dielectric constant and dielectric loss tangent of TG value is small, and no effects by frequency change, as an insulation material for communication cable, is a nearly ideal medium.
(2) good mechanical properties, rich flexibility, and good toughness, tolerable.
(3) heat aging resistance, low temperature resistance and good chemical stability.
(4) good water resistance, low moisture absorption, immersion in water, the insulation resistance is generally not decreased.
(5) as a non polar material, the permeability of the low density polyethylene is the most excellent one in all kinds of plastics.
(6) the proportion of light, its proportion is less than 1. High pressure polyethylene is particularly prominent, about 0.92g/cm3; low pressure polyethylene, although its density is larger, it is only about cm3 0.94g/.
(7) with good processing performance, easy to melt and plastic, and not easy to break down, the cooling is easy to shape, the product geometry and structure size is easy to control.
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(8) with its light weight, easy to use, easy to lay, easy to use, and easy to use.
But there are many disadvantages: Polyethylene low softening temperature; easy to contact with the flame combustion and melting, and release and smell the same wax burning; resistance to environmental stress cracking resistance and creep is poor in polyethylene as a submarine cable and a large drop (especially vertical laying) using cable insulation and sheath material should pay special attention to.
Polyethylene plastics for wire and cable
(1) polyethylene plastics for general insulation
Only composed of polyethylene resin and antioxidant.
(2) weather resistant polyethylene plastics
Mainly composed of polyethylene resin, antioxidant, and carbon black. Weathering performance depends on the particle size and carbon content, and dispersion.
(3) resistance to environmental stress cracking of polyethylene plastics
Using the melt index 0.3 or less, the molecular weight distribution is not too wide, and the polyethylene is irradiated or chemically cross-linked.
(4) polyethylene plastics for high voltage insulation
Polyethylene plastic high voltage cable insulation requirements of highly pure, also need to add the voltage stabilizer and the special extruder, avoid pores, to inhibit the increase of polyethylene resin discharge, arc resistance, resistance to corrosion and corona resistance.
(5) semi conductive polyethylene plastic
Semi conductive polyethylene plastic with conductive carbon black obtained in polyethylene, generally using fine diameter and high structure carbon black.
(6) thermoplastic low smoke halogen free flame retardant polyolefin cable material
The cable material is a polyethylene resin as base material, with high quality and efficient non-toxic halogen-free flame retardant and smoke suppressant, heat stabilizer, anti mildew agent, colorant modified additives, through mixing, plasticizing, granulation.
Crosslinked polyethylene
Under the action of high energy beam or cross linking agent, the molecular structure of the linear molecular structure can be changed into the shape of the molecular structure. Make thermoplastic materials into thermosetting materials. With crosslinked polyethylene as insulating material, long-term working temperature can be increased to 90oC, the transient short circuit temperature can reach 170 ~ 250oC. Cross linked polyethylene crosslinking methods are: physical and chemical crosslinking. Radiation crosslinking belongs to physical crosslinking, chemical crosslinking crosslinking agent is the most commonly used DCP (two cumene peroxide).
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