POLYMERS USED IN CABLE INSULATION AND SHEATHING

POLYMERS USED IN CABLE INSULATION AND SHEATHING

Polymers are insulating materials that are insulating against electricity and heat. Being insulating against electricity is the main reason for its use in cable insulation and sheathing.
Another reason is that it is resistant to chemical corrosion and effects.

Polymers are generally divided into three.

• Thermoplastics
• Thermosets
• Elastomers

TERMOPLASTICS on

When heated, they soften and flow, and when cooled, they harden and solidify. This cycle is repeatable for thermoplastics. During shaping
they do not undergo any chemical changes. If we give an example to thermoplastics; PVC, Polyethylene, Plopropylene.

TERMOSETS on

After heat treatment, they take the desired shape, but they cannot be reheated and shaped. These materials are very resistant to solvents. They have a cross-linked structure.
As an example of thermosets; XLPE, XLHFFR can be given.

ELASTOMERS

Cross-linked rubber-like polymers or rubber-like web structures are called elestomers, which elongate very high when a pulling force is applied and return to its initial size when the pulling force is removed.
Elastomer is the network structure formed by the sparse crosslinking of polymers. As an example of elastomers; EPDM, SBR can be given.

All of the polymers are good insulators at neurovoltage and frequencies. The insulating feature decreases as the ambient temperature increases. Polymers are dielectric materials.
Each polymer has a dielectric constant and is greater than 1.9 – 2.

Polyethylene: It has 2.33 dielectric constant and provides excellent electrical insulation.

PVC: It has 4 – 8 dielectric constant. Although it has a good viscosity, its insulation is low compared to polyethylene.

Silicone: It has around 3 dielectric constants.

Additives introduced into polymers can cause the dielectric constant to rise or fall.

Polymer should be selected according to the characteristics of the cable to be produced. The main criteria in this selection can be concluded as follows.

1. Insulation feature (electrical)
2. Resistance to mechanical strain and impacts
3. Effects in the working environment
• Temperature
• Chemicals
UV resistance
• Flame and fire resistance
4. Flexibility
5. Life

DIELECTRIC FIXES OF POLYMERS

PVC: 4 ~ 8
PE: 2.33
PE (physical foam): 1.6 ~ 2.1
SILICONE: 3.2 ~ 4.7
PP: 2.23
XLPE: 2.33
HFFR (thermoplastic): ~ 4
HFFR (thermoset): ~ 4
POLYURETHANE: ~ 6

CABLE INSULATION AND SHEATH POLYMERS

PVC (poklivinil chloride)
LDPE (low density polyethylene)
HDPE (high density polyethylene)
XLPE (cross-linked polyethylene)
PP (polypropylene)
TPU (thermoplastic polyurethane)
TPE (thermoplastic elastomer)
SIR (silicone rubber)
HFFR, LSZH, LS0H (hffr compounds)
-TERMOPLASTIC HFFR
-TERMOSET HFFR