Introduction
Firstly let’s explain what cable insulation and sheath are.
- Insulation:A non-conductive substance called dielectric that surrounds a conductor.
- Sheath:The overall covering of a cable, also known as the outer jacket – protects the cable from environmental influences and stresses.
Types of Insulation and Sheathing Materials
In this article I have categorised cable insulation and sheathing materials into
- Thermoplastic Materials
- Elastomeric Materials
- High-Temperature Materials
1. Thermoplastic Materials
Thermoplastic Materials: A material that softens when heated and is strong when cooled.
PVC (Polyvinyl Chloride)
PVC is widely used as an insulating material for wires and cables and as a sheathing material for many types of cables. In addition to common PVC materials, there are also high temperature resistant PVC and low temperature resistant PVC materials to meet the needs of different environments. PVC materials are flame retardant and abrasion resistant, but it should be noted that it is NOT LSZH.
PE (Polyethylene)
PE material has excellent dielectric properties, strong and durable, friction resistance, and good low temperature fluidity. Usually we use this material as insulation and sheathing for cables with high requirements. However, it is NOT flame retardant compared to PVC.
PP (Polypropylene)
PP cable is similar to PE, but it is harder and has better temperature resistance and excellent electrical properties. Cables made of this material are often used for special applications, such as submarine cables and automotive wiring harnesses.
XLPE (Cross-Linked Polyethylene)
XLPE material has excellent high temperature resistance, fire retardant, weather resistance and electrical properties to ensure long term operation of the cable. Cables made of this material are ideally suited for large construction projects, public transport projects, city power supplies, etc. and are more often used for high voltage cables.
XLPO (Cross-Linked Polyolefin)
XLPO cables, as a new material this year. This material has excellent mechanical strength, high temperature resistance and aging resistance. We can see this material in photovoltaic cables, and some EV charging pile cables. It can even guarantee 25 years of operation, even if the PV cable is exposed to harsh outdoor environments for a long time.
PUR (Polyurethane)
This material is known for its good resistance to abrasion, solvents and hydrolysis. It is very suitable for equipment cables in chemical plants and other places. This material is also used in the production of spiral cables because of its excellent resilience. However, its electrical properties are not as good in comparison.
| Material | Working Temperature | Key Features | Applications |
| PVC (Polyvinyl Chloride) |
-30~70℃ | – Flame-retardant | General insulation jacket |
| – Abrasion-resistant | |||
| – Not LSZH (Low Smoke Zero Halogen) | |||
| PE (Polyethylene) |
-50~70℃ | – Excellent dielectric properties | High-performance insulation and sheathing for cables |
| – Durable and friction-resistant | |||
| – Not flame-retardant | |||
| PP (Polypropylene) |
-10~90℃ | – Good electrical properties | Submarine cables |
| – Higher temperature resistance | Automotive wiring harnesses | ||
| – Suitable for specialized applications | |||
| XLPE (Cross-Linked Polyethylene) |
-35~90℃ | – Excellent high-temperature resistance | Large construction projects |
| – Fire retardant | High-voltage cables | ||
| – Weather-resistant | City power supplies | ||
| – Strong electrical properties | |||
| XLPO (Cross-Linked Polyolefin) |
-40~90℃ | – High mechanical strength | Photovoltaic cables |
| – High-temperature resistance | EV charging pile cables | ||
| – Aging resistance | |||
| – Long-term outdoor use | |||
| PUR (Polyurethane) |
-40~80℃ | – Abrasion, solvent, and hydrolysis-resistant | Chemical plants |
| – Excellent resilience | Spiral cables | ||
| – Poor electrical properties compared to others | Equipment cables |
2. Elastomeric Materials
A material that returns to its original dimensions after stretching. Elastomers are rubber or rubber-like materials that can be repeatedly stretched by 200% or more and returned quickly and forcefully to their approximate original shape.
NR (Natural Rubber)
NR Natural Rubber has good elasticity and excellent electrical properties, and is superior to most synthetic rubbers in terms of overall performance.
However, it has poor oxygen and ozone resistance, is NOT very resistant to oils and solvents, and is susceptible to aging.
Neoprene (CR – Chloroprene Rubber)
This rubber material contains chlorine atoms. Therefore, compared to other rubbers, this material has excellent oxidation resistance and can be self-extinguishing after catching fire. It is resistant to oil, solvents, acids and alkalis, and aging. The main disadvantages are poor cold resistance and relatively heavy weight.
SiR (Silicone Rubber)
This rubber material is heavy in silicon and oxygen atoms. Its main characteristics are high temperature resistance (maximum operating temperature of 200 ℃), low temperature resistance (minimum -60 ℃). Currently it is the best high temperature resistant rubber, as well as excellent electrical properties, resistance to ozone and oxidation.
But it’s lower mechanical strength; oil, solvents, acid and alkali resistance is poor, expensive.
EPR (Ethylene Propylene Rubber)
Ethylene propylene rubber is ethylene, propylene as the main material of synthetic rubber, binary ethylene propylene rubber and ternary ethylene propylene rubber.
The former is a copolymer of ethylene and propylene, expressed as EPM, and the latter is a copolymer of ethylene, propylene and a small amount of non-conjugated diolefin third monomer, expressed as EPDM.
The two are collectively known as ethylene propylene rubber (EPR).
EPR has excellent ozone and UV resistance and is very suitable for outdoor applications. It maintains its flexibility and elasticity at high and low temperatures. It also has a low water absorption rate, enabling it to withstand humid environments and prevent damage to cable insulation. The disadvantage is that it is difficult and costly to produce.
CSM (Chlorosulfonated Polyethylene)
This material is an elastic polymer obtained by chlorination and sulphonation of polyethylene. It has excellent ozone resistance and aging resistance, and its weather resistance is superior to other rubbers. It has good flame retardancy, heat resistance, solvent resistance, acid and alkali resistance. The disadvantage is that the tear resistance is poor.
NBR (Nitrile Rubber)
This rubber material is a copolymer of butadiene and acrylonitrile. It is characterised by excellent resistance to petrol and aliphatic hydrocarbon oils. It has good heat resistance, air tightness, abrasion resistance and water resistance. Disadvantages include poor cold and ozone resistance, low elasticity, and poor acid resistance.
| Material | Working Temperature | Key Features | Applications |
| NR
(Natural Rubber) |
-65~60℃ | – Superior overall performance to most synthetic rubbers | General insulation and sheathing |
| – Poor oxygen and ozone resistance | |||
| – Not resistant to oils and solvents | |||
| – Susceptible to aging | |||
| CR
(Chloroprene Rubber, Neoprene) |
-40~100℃ | – Self-extinguishing after fire | Industrial cables |
| – Excellent oxidation resistance | Marine and mining cables | ||
| – Resistant to oil, solvents, acids, and alkalis | |||
| – Poor cold resistance and heavy weight | |||
| SiR
(Silicone Rubber) |
-60~200℃ | – High temperature resistance (up to 200°C) | High-temperature cables |
| – Low temperature resistance (-60°C) | Aerospace and medical applications | ||
| – Excellent electrical properties | |||
| – Resistant to ozone and oxidation | |||
| – Expensive, low mechanical strength | |||
| EPR
(Ethylene Propylene Rubber) (EPDM) |
-30~90℃ | – Excellent ozone and UV resistance | Outdoor power cables |
| – Retains elasticity at high and low temperatures | Submarine cables | ||
| – Low water absorption, ideal for humid environments | |||
| – Difficult and costly to produce | |||
| CSM
(Chlorosulfonated Polyethylene) |
-30~80℃ | – Outstanding weather and ozone resistance | Harsh environmental applications |
| – Flame retardant, heat-resistant | Chemical-resistant cables | ||
| – Good solvent, acid, and alkali resistance | |||
| – Poor tear resistance | |||
| NBR
(Nitrile Rubber) |
-40~90℃ | – Excellent resistance to petrol and hydrocarbon oils | Oil-resistant cables |
| – Good heat resistance, airtightness, and water resistance | Industrial machinery wiring | ||
| – Poor cold resistance, low elasticity, and poor acid resistance |
3. High-Temperature Materials
Wires and cables with thermal operating characteristics of 150°C and higher. The main focus here is on fluoroplastics.
ETFE (Ethylene Tetrafluoroethylene)
This material is a copolymer of ethylene & tetrafluoroethylene and is the toughest fluoropolymer with excellent chemical resistance.
Operating temperature range: -200℃~150℃.
FEP (Fluorinated Ethylene Propylene)
This material is the more common fluoroplastic for cables, with good flame retardant properties and excellent abrasion resistance.
Operating temperature range: -100℃~200℃.
PTFE (Polytetrafluoroethylene)
This material has excellent chemical resistance and excellent electrical properties. However, the abrasion resistance and tensile strength are poor.
Operating temperature range: -190℃~260℃.
PFA (Perfluoroalkoxy)
This material retains the same properties as PTFE, and has superior mechanical properties compared to PTFE. However, the cost of this material is quite expensive.
Operating temperature range: -190℃~260℃.
| Material | Working Temperature | Key Features |
| ETFE
(Ethylene Tetrafluoroethylene) |
-200°C to 150°C | – Toughest fluoropolymer |
| – Excellent chemical resistance | ||
| FEP
(Fluorinated Ethylene Propylene) |
-100°C to 200°C | – Good flame retardancy |
| – Excellent abrasion resistance | ||
| PTFE
(Polytetrafluoroethylene) |
-190°C to 260°C | – Excellent electrical properties |
| – Poor abrasion resistance and tensile strength | ||
| PFA
(Perfluoroalkoxy) |
-190°C to 260°C | – Retains PTFE properties |
| – Higher mechanical strength | ||
| – Expensive |
Conclusion
Understanding the properties of different cable insulation and sheath materials helps in choosing the right cable for specific applications. Selecting the appropriate material ensures durability, safety, and long-term performance.
Need help selecting the right cable? Contact us for expert recommendations!
