Insulation & Sheath Material Properties In General

Characteristics of Thermoplastic Insulating and Sheath Materials

Characteristics of Elastomeric Insulating and Sheath Materials

Characteristics of High Temp. Insulation and Sheath Materials

PVC
Polyvinyl chloride (PVC) is durable, cheap, and easily worked. It can be made softer and more flexible by the

addition of plasticizers. There are many formulations for the variety of different applications. The many varieties

of PVC also differ in pliability and electrical properties.

PE
Polyethylene (PE) is a thermoplastic polymer consisting of long chains produced by combining the ingredient

monomer ethylene. It has good electrical properties. In terms of flexibility, polyethylene can be rated stiff to very

hard, depending on molecular weight and density—low density being the most flexible, with high-density, high-

molecular weight formulation being very hard. Moisture resistance is rated excellent. Black and specially

formulated colored versions have excellent weather resistance.

LDPE

Low Density Polyethylene has a high degree of short and long chain branching, which means that the chains do

not pack into the crystal structure as well. It has, therefore, less strong intermolecular forces as

the instantaneous-dipole induced-dipole attraction is less. This results in a lower tensile strength and

increased ductility. LDPE is created by free radical polymerization. The high degree of branching with long chains

gives molten LDPE unique and desirable flow properties.

HDPE 
High Density Polyethylene has a low degree of branching and thus stronger intermolecular forces and tensile

strength. The lack of branching is ensured by an appropriate choice of catalyst (for example, chromium catalysts

or Ziegler-Natta catalysts) and reaction conditions. It is generally used as a sheathing material where it provides

high resistance to water penetration, is very hard, has low coefficient of friction, and is abrasion resistant.

XLPE
By introducing chemical bonding between the chains in PE we get cross-linked polyethylene (XLPE), a thermoset

type of PE. It improves the properties of the cables and makes it suitable for power transmission. XLPE has very

good mechanical strength, low density. It can be used at high temperature above 110°C where the normal

Polyethylene compounds are thermally unstable.

Polyamide (Nylon)

Nylon is a generic designation for a family of synthetic polymers known generically as polyamides. It has good

durability, high elongation, excellent abrasion resistance and high resilient. It also resists insects, fungi, molds,

midew, rot and many chemicals.

Polypropylene

Polypropylene (PP), also known as polypropene, is normally tough and flexible, especially when

copolymerized with ethylene. It is similar as polyethylene in electrical properties. This material is primarily used

as an insulation material. Typically, it is harder than polyethylene. This makes it suitable for thin wall insulations.

Polyurethane

Polyurethane (PUR and PU) combines the best properties of both rubber and plastic. This material is used

primarily as a cable jacket material. It has excellent oxidation, oil, and ozone resistance. Some formations also

have good flame resistance. It is a hard material with excellent abrasion resistance.

TPE 

Thermoplastic Elastomer. TPE is cross linkable elastomers with styrenic rubbers which gives homogenous

compound excellent hybrid properties with rubbery effect. TPE gives advantage to cost effective and achieves

high performance applications and specification to thermoset rubbers. TPE is normally tough, cut resistant,

flexible, smooth, with vibrant coloring.

LSZH

Low smoke zero halogen or low smoke free of halogen is composed of thermoplastic or thermoset compounds

that emit limited smoke and no halogen when exposed to high sources of heat, e.g. flame. In a fire, a halogen-

containing plastic material releases, e.g. hydrogen chloride, a poisonous gas that forms hydrochloric acid when it

comes in contact with water. Designated Halogen-free cables, on the other hand, do not produce a dangerous

gas/acid combination or toxic smoke when exposed to flame. Low smoke zero halogen cable reduces the

amount of toxic and corrosive gas emitted during combustion. This type of material is typically used in poorly

ventilated areas such as aircraft or rail cars. Low smoke zero halogen is becoming very popular and, in some

cases, a requirement where the protection of people and equipment from toxic and corrosive gas is critical.

It is often lighter, so overall cable network system weights can be reduced. The environmental impact of halogen

free cabling can be lower if there are fewer toxic chemicals.

HFFR ( Low smoke , Flame retardant , Halogen-free and Thermoplastic compounds)

When PVC is not acceptable due to the problems chlorine (halogen) containing materials present in the event of

a fire HFFR must be used. (In accordance with IEC 60092-359 type SHF1). The materials will not propagate a fire

along a cable run, drip or give off black smoke. No acid gases will be released during a fire that can corrode and

damage expensive equipment.

CPE

Chlorinated Polyethylene. An oil, ozone and heat resistant sheathing compound.

Rubber

Rubber normally includes natural rubber and SBR compounds.

Natural rubber is an elastomer (an elastic hydrocarbon polymer) that was originally derived from latex, a

milky colloid produced by some plants. It is normally very stretchy and flexible and extremely waterproof. Rubber

exhibits unique physical and chemical properties. Rubber’s stress-strain behavior exhibits the Mullins effect, the

Payne effect, and is often modeled as hyperelastic. Owing to the presence of a double bond in each repeat unit,

natural rubber is sensitive to ozone cracking.

Styrene-butadiene rubber (SBR) is asynthetic rubber copolymer consisting of styrene and butadiene. It has

good abrasion resistance and good aging stability when protected by additives. it offers good durability, less

shrinkage and flexibility, as well as being resistant to emulsification in damp conditions.

Synthetic rubber
Synthetic rubber is any type of artificial elastomer, invariably a polymer. An elastomer is a material with the mechanical (or material) property that it can undergo much more elastic deformation under stress than most materials and still return to its previous size without permanent deformation. Synthetic rubber serves as a substitute for natural rubber in many cases, especially when improved material properties are required.

Silicon Rubber

Silicone rubber is an elastomer (rubber-like material) composed of silicone—itself

a polymer—containingsilicon together with carbon, hydrogen, and oxygen. Silicone rubber offers good resistance

to extreme temperatures, being able to operate normally from −55 °C to +300 °C. At the extreme temperatures,

the tensile strength, elongation, tear strength and compression set can be far superior to conventional rubbers

although still low relative to other materials. Organic rubber has a carbon to carbon backbone which can leave

them susceptible to ozone, UV, heat and other ageing factors that silicone rubber can withstand well. This

makes it one of the elastomers of choice in many extreme environments. Compared to organic rubbers,

however, silicone rubber has a very low tensile strength.[1] For this reason, care is needed in designing

products to withstand even low imposed loads. The material is also very sensitive to fatigue from cyclic loading.

Silicone rubber is a highly inert material and does not react with most chemicals.

Nitrile Butadiene Rubber (NBR)

Nitrile butadiene rubber (NBR) is a family of unsaturated copolymers of 2-propenenitrile and various butadiene

monomers (1,2-butadiene and 1,3-butadiene). Although its physical and chemical properties vary depending on

the polymer’s composition of nitrile, this form of synthetic rubber is generally resistant to oil, fuel, and other

chemicals (the more nitrile within the polymer, the higher the resistance to oils but the lower the flexibility of the

material).

NBR/PVC

NBR/PVC is admixture of NBR and PVC. It unite both advantages of those two materials. It has better ability to

resist oil, chemicals, ozone and weather.

Polybutadiene

Polybutadiene is a highly resilient synthetic rubber. Heat buildup is lower in polybutadiene rubber based

products subjected to repeat flexing during service. It is sensitive to oxidation and ozone owing to the reactivity

of the double bond present in every repeat unit. Anti-oxidants are normally added to protect against cracking

and deterioration.

EPR 

Ethylene Propylene Rubber. A water and ozone resistant, flexile, cross linked high grade insulation material.

However, relatively poor cold traction and cut growth resistance limits the use to blends with other types of

rubber.

EVA (Flame retardant halogen-free termoset compound)

EVA, ethylene vinyl acetate, is a multi-functional elastomer, which resists the combined deteriorating influences

of heat, oil and weather. (In accordance with IEC 60092-359 type SHF2).

For offshore applications, EVA can be compounded to produce high quality cable sheathing with low smoke and

flame propagation, and with no emission of halogenous acids.

It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other

thermoplastics. The material has good clarity and gloss, barrier properties, low-temperature toughness, stress-

crack resistance, hot-melt adhesive water proof properties, and resistance to UV radiation. EVA has little or no

odor and is competitive with rubber and vinyl products in many electrical applications.

Neoprene (Polychloroprene)

Neoprene in general has good chemical stability, and maintains flexibility over a wide temperature range. It is

both oil-resistant and sunlight-resistant, making it ideal for many outdoor applications. The most stable colors

are Black, Dark Brown, and Gray. The electrical properties are not as good as other insulation materials.

CSPE (CSM) 

Chlorosulphonated Polyethylene. Oil, ozone and heat resistant sheathing material. 

EPDM

EPDM (ethylene-propylene-diene elastomer), is a hydrocarbon rubber that combines electrical performance

suitable for fire resistant offshore cables with mechanical toughness and resistance to ozone, UV light and heat.

It's wet electrical properties are unique. It is very flexile at high and low temperatures ( -55°C to 150°C). It has

good insulation resistance and dielectric strength, as well as excellent abrasion resistance. EPDM also has

better cut-through resistance than Silicone rubber, which it replaces in some applications.

EPDM exhibits satisfactory compatibility with fireproof hydraulic fluids, ketones, hot and cold water, and alkalis,

and unsatisfactory compatibility with most oils, gasoline, kerosene, aromatic and aliphatic hydrocarbons,

halogenated solvents, and concentrated acids.

PVDF

Polyvinylidene fluoride, or polyvinylidene difluoride (PVDF) is a highly non-reactive and pure thermoplastic

fluoropolymer. PVDF is a specialty plastic material in the fluoropolymer family; it is used generally in applications

requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low smoke

generation during a fire event. Compared to other fluoropolymers, it has an easier melt process because of its

relatively low melting point of around 177 °C. It has a low density (1.78) and low cost compared to the other

fluoropolymers.

Polytetrafluoroethylene

It is a synthetic fluoropolymer oftetrafluoroethylene. The most well known brand name of PTFE is Teflon. PTFE is

a fluorocarbon solid, as it is a high-molecular-weight compound consisting wholly of carbon and fluorine. It is

hydrophobic. PTFE has one of the lowest coefficients of friction against any solid.

PTFE has excellent dielectric properties. Combined with its high melting temperature, this makes it the material

of choice as a high-performance substitute for the weaker and lower melting point polyethylene that is

commonly used in low-cost applications. This material has excellent temperature range and chemical resistance.

It is not suitable where subjected to nuclear radiation and does not have good high voltage characteristics.

PFA

Perfluoroalkoxy (PFA) is very similar in composition to the fluoropolymers PTFE and FEP (fluorinated ethylene-

propylene). PFA and FEP both share PTFE’s useful properties of low coefficient of frictionand non-reactivity, but

are more easily formable. PFA is similar to FEP in terms of its mechanical properties. These two are both superior

to PTFE with regards to their flexibility. However, their ability to endure repetitive folding (flex life) is actually

lower than PTFE. PFA has a higher flex life than FEP. PFA is preferable to FEP where heat is concerned, but PTFE

itself is slightly more resistant to heat than both. PFA is more affected by water absorption and weathering than

FEP, but is superior in terms of salt spray resistance.

FEP

In terms of corrosion resistance, Fluorinated ethylene propylene (FEP) is the only other readily available

fluoropolymer that can match PTFE's own resistance to caustic agents, as it is a pure carbon-fluorine structure

and fully. Thermally, FEP stands out from PTFE and PFA by having a melting point of 260 °C (500 °F), around

forty degrees lower than PFA and lower again than PTFE. Electrically, PTFE, FEP and PFA have identical dielectric

constants, but FEP's dielectric strength is only surpassed by PFA. However, whilst PFA has a similar dissipation

factor to PTFE, FEP's dissipation is around six times that of PFA and EFTE (making it a more non-linear conductor

of electrostatic fields).

TFE

TFE Teflon is extrudable in a hydraulic ram type process. Lengths are limited due to amount of material in the

ram, thickness of the insulation, and preform size. TFE must be extruded over a silver- or nickelcoated wire. The

nickel- and silver-coated designs are rated 260°C and 200°C maximum, respectively. The cost of Teflon is

approximately 8 to 10 times more per pound than PVC compounds