Characteristics of Polyethylene
Polyethylene is a milky white plastic, waxy and translucent surface is ideal wire and cable insulation and jacketing materials. Its main advantages are:
(1) excellent electrical properties. High insulation resistance and electric strength; over a wide frequency range, the dielectric constant ε and the dielectric loss tangent value of tgδ and substantially independent of frequency change, as the communication cable insulation materials are almost ideal one medium.
(2) mechanical properties, full flexibility, and tough, resistant capacitive good.
(3) heat aging resistance, low temperature resistance, cold resistance and chemical stability.
(4) good water resistance, low moisture absorption, insulation resistance immersed in water is generally not declined.
(5) as the non-polar materials, a large gas permeability, the permeability is low-density polyethylene is the most excellent in various plastics.
(6) the proportion of light, its specific gravity less than one. LDPE is particularly prominent, about 0.92g / cm3; large low pressure polyethylene, although its density is only about 0.94g / cm3.
(7) has a good processing performance, easy-to-melt plasticizing, and difficult to break down, cooling easy molding, product geometry and structure size easy to control.
(8) with its light weight wire and cable production, use, laying convenient, easy fitting.
But there are many disadvantages of polyethylene: the softening temperature is low; contact with the flame burning and melting easy, and emit the same smell when burning paraffin; poor resistance to environmental stress cracking resistance and creep resistance, as the seabed in polyethylene cables and larger gap (especially vertical laying) when the cable insulation and sheathing materials using special attention. Wire and cable polyethylene plastic
(A) General insulated polyethylene plastic
（1）Only the polyethylene resin and an antioxidant composition.
(2) weather polyethylene plastic
Mainly composed of a polyethylene resin, an antioxidant, and carbon black composition. Weathering performance is good or bad depends on the particle size of the carbon black content, and dispersion.
(3) resistance to environmental stress cracking of polyethylene plastic
Melt index of 0.3 or less, not too wide molecular weight distribution polyethylene; irradiation or chemical cross-linking of the polyethylene for.
(4) high-voltage insulated with polyethylene plastic
Polyethylene plastic for high voltage cable insulation highly pure, still need to add a voltage stabilizer and using a special extrusion machine, avoid pores produce to inhibit resin discharge, increase polyethylene arc resistance, corrosion resistance and electrical corona .
(5) semi-conductive polyethylene plastic
Semi-conductive polyethylene plastic is added conductive carbon black in polyethylene obtained, the general should be fine particle size carbon black, high structure.
(6) Thermoplastic LSZH polyolefin cable material
This kind of cable is a polyethylene resin-based material, adding quality and efficient halogen-free non-toxic flame retardants, smoke suppressants, heat stabilizers, fungicides, additives, coloring agents modified by mixing, plasticizing , granulating