What Are The Main Plastic Cable Materials?

What Are the Main plastic raw materials for Power Cables?

The materials used for electric wires and cables can be divided into conductive, insulating, sheathing, shielding, filling materials, etc. according to their use and function. According to their properties, they can be divided into metal (copper, aluminum, aluminum alloy, steel), plastic (PVC, PE, PP, XLPE/XL-PVC, PU, TPE/PO), and rubber. However, some of these materials are common to several structural components. In particular, thermoplastic materials such as polychlorinated ethylene and polyethylene can be used for insulation or sheathing if part of the formulation composition is changed.
Next, we introduce our commonly used non-metallic wire and cable raw materials

 

Polyvinyl chloride (PVC)

PVC is generally used as insulation and sheathing material. PVC is wire and cable insulation with the performance: not easy to burn, aging, oil, chemical resistance, impact resistance, and easy to color; but due to the large dielectric constant, generally only as low-voltage cable insulation and control cable insulation materials.

PVC as wire and cable sheathing performance: good abrasion resistance, resistance to oil, acid, alkali, bacteria, moisture, and sunlight, etc., and the role of flame has self-extinguishing properties; PVC sheathing minimum working temperature of -40 degrees, high-temperature resistance up to 105 degrees.

 

Polyethylene (PE)

PE’s general physical properties: white waxy, translucent, soft and tough, slightly elongated, lighter than water, non-toxic; burning characteristics: flammable, continue to burn after leaving the fire, the upper end of the flame is yellow and the lower end is blue, molten drops when burning, the smell of burning paraffin; polyethylene processing melting point range is 132 ~ 1350C, the fire temperature is: 3400C, the spontaneous combustion temperature is: 3900C.

Polyethylene (PE) is generally divided into several categories: LDPE, MDPE, HDPE, and FMPE.

1, LDPE: Low-density polyethylene is the lightest of the polyethylene series, also known as low-pressure polyethylene, structural characteristics are non-linear, score it has a low crystallinity and softening point, has good flexibility, elongation, electrical insulation, transparency, as well as high impact strength. LDPE has poor mechanical strength, low heat resistance, and, in addition, an obvious weakness is its poor resistance to environmental stress cracking.

2, MDPE: medium-density polyethylene, also known as medium-pressure polyethylene and Phillips polyethylene, its performance and high-density polyethylene exorcise, the plant is no longer used, not detailed here.

3, HDPE: High-density polyethylene compared to low-density polyethylene, also known as high-pressure polyethylene, has excellent overall performance, such as improved heat resistance and mechanical strength (such as tensile length, bending strength, compression strength, and shear strength), and improved barrier performance to water vapor and gas, superior resistance to environmental stress cracking.

4, FMPE: foamed PE is the most widely used foam material, using chemically foamed foam polyethylene, its dielectric constant can be reduced to about 1.55. If the new process of physical foaming is adopted, that is, inert gas (nitrogen or air) is injected into the melted polyethylene to foam when extruding, the foamed polyethylene with smaller bubble size can be made, the foaming degree can be controlled between 35-40%, more than 40% piebald, its dielectric constant can be reduced to about 1.20, and because the chemical foaming agent is not used, the insulation does not contain the residue of foaming agent, the dielectric loss can also be The loss has reached the level of air insulation.

Polyethylene has excellent electrical insulation properties and is widely used for the insulation of communication cables; to improve the technical-economic indicators of communication cables, foam polyethylene is generally used. Generally, the smaller the molecular weight (the higher the melt index), the worse the resistance to environmental stress cracking. Those with a melt index of 0.4 or less can avoid environmental stress cracking. For densities around 0.950, the smaller the melt index, the most resistant to environmental stress cracking. If the density is greater than 0.95, the resistance to environmental stress cracking becomes worse, but lower densities with the same melt index are much better. However, HDPE often has residual internal stresses during molding, which should be noted during use.

PE mixed with EVA in a certain ratio can improve environmental stress cracking; mixed with PP can improve hardness; mixed with PE of different densities, can adjust its softness and hardness.

 

Ethylene-vinyl acetate copolymer (EVA)

EVA is a class of elastic thermoplastics with a class of exorbitant rubber, its performance and vinyl acetate (VA) content have a great relationship: the smaller the VA-like high-pressure polyethylene, the more VA-like rubber. low VA content of EVA exorbitant high-pressure polyethylene, soft and good impact strength, suitable for the manufacture of composite materials.

EVA has good elasticity and low-temperature flexibility, chemical resistance, weather resistance, and LDPE copolymer use, which can improve the environmental cracking resistance of LDPE, impact resistance, softness and hardness, and adhesion between the conductor and insulation.

 

Polypropylene (PP)

The specific gravity of polypropylene is 0.89-0.91, which is the smallest of the commonly used plastics, with excellent mechanical strength, the highest softening temperature in thermoplastic resins, good low-temperature resistance, and good aging resistance; only the spin resistance is slightly poor but can be improved by adding stabilizers through co-polymerization.

General properties of polypropylene: PP is very similar to HDPE in appearance, it is a white waxy solid, more transparent than PE, non-toxic, combustible, and will continue to burn after leaving the fire, and emits the smell of petroleum noxious.

Compared to polyethylene, polypropylene has the following different characteristics.

1, PP surface hardness than PE, wear resistance, and bending deformation ability are very good, so PP has “low density and high strength plastic” called.

2, Another advantage of PP over PE is that there is almost no environmental stress cracking, PP has an extremely good resistance to environmental stress cracking. However, the high degree of regularity in the molecular structure of PP itself makes its impact performance at room temperature and low temperature very poor.

3, PP electrical insulation performance: PP is a non-polar material, so it has very good electrical insulation.

Its electrical insulation properties are essentially similar to those of LDPE and do not change over a wide range of frequencies. Because of its extremely low density, the dielectric constant than LDPE is also small (ε = 2.0 ~ 2.5), dielectric loss angle tangent for 0.0005 ~ 0.001, volume resistance coefficient of 1014Ω.m above, the breakdown field strength is also very high, 30MV/m; coupled with very small water absorption, so PP can be used as high-frequency insulation materials.

 

Polyester

These materials are characterized by high modulus, high tear resistance, high abrasion resistance, high elasticity, and low hysteresis, with an upper-temperature range of 1500C, which greatly exceeds that of other thermoplastic rubbers, and excellent oil and solvent resistance.

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