Plastic in Common Use for Wire and Cable ( II )
PVC has good physical and mechanical properties and excellent process performance. It is the most used plastic in twentieth Century, and also the main insulating material and sheath material for low voltage wire and cable. But in twenty-first Century, PVC will gradually shrink or even fade out in the cable market.
There are two reasons for it. On the one hand, people’s safety awareness is improved, and they hope to use halogen free materials. Therefore, many halogen free materials emerge as the times require. There is no doubt that it will become the new favorite of the cable industry in twenty-first Century and occupy the market.
On the other hand because PVC has five weaknesses: one is the density, is about 1.5 times of XLPE insulation, and high cost; two is the low working temperature; three is the high dielectric loss, more than 100 times higher than the crosslinked polyethylene; four is cold tolerance (-15 is brittle; five is burning) burning gas (HCL) released.
In recent years the development of crosslinked PVC mechanical properties, electric properties, insulation resistance is greatly improved, some small section cable using irradiation technology to enter the market, in the equipment with wire, high voltage wiring, automotive wire and building wiring has been applied, but it has the disadvantage of being unable to change the halogen.
Fluoroplastics are widely used in wire and cable because of their many advantages such as high working temperature, small medium, insulation, weather resistance, acid and alkali resistance, oil resistance and good flame retardancy. Especially, polyfluoroethylene propylene is very popular because of its good technological nature. But the price is expensive, the user had to think twice.
Low smoke halogen-free polyolefin is a new type of cable sheath material developed in the twentieth Century. Its biggest advantage is its flame retardancy and low smoke and no gas in combustion. It has been widely applied in important public buildings.