Wiring And Cables

Plasticised polyvinyl chloride (PVC) is the most widely used electrical insulation material in use today. Not only is it the most commonly specified material for protecting wires in the many thousands of different types of machines and appliances that we have come to rely upon in our everyday lives, it is also the preferred insulation for transmission cables and for the very latest fibre optics. 

By volume, about 25 per cent of all plasticised PVC is used by the wire, cable and electrical industries.

Plasticised PVC is the preferred choice because it offers the benefits of long service life and durability in a wide range of conditions at exceptionally competitive prices.

Flexibility

PVC's ability to bend and twist without cracking is a feature which makes it particularly suitable for a wide range of applications. This flexibility is provided by the addition of plasticisers that are mixed with the PVC before it is typically extruded around the metal wires it has to insulate and sheath.

Depending on the application, there are a variety of different plasticisers that can be used, ranging from general-purpose plasticisers like phthalates to more special purpose ones such as trimellitates, phosphates, and polymeric plasticisers.

General-purpose plasticisers

Phthalates are widely used as general-purpose plasticisers because they offer the advantage of lower costs and increased production efficiency. This is achieved through improved melt viscosity and production speeds of heated PVC with phthalates added. Increased flow characteristics give better workability and reduced out-of service breaks in equipment.
Phthalates are a family of substances which have a similar molecular structure. Different individual phthalates, however, confer particular qualities. By varying the phthalate used, cable manufacturers are able to produce a wide range of sheathing for particular applications.

Phthalate plasticisers, in particular di-2-ethylhexyl phthalate (DEHP or DOP), diisononyl phthalate (DINP) dipropylheptyl phthalate (DPHP), and diisodecyl phthalate (DIDP), meet a wide range of operating demands. This is vital, for example, for energy cables used in buildings or for energy distribution wiring buried in the ground which should remain flexible even at low temperatures.

Special-purpose plasticisers

Trimellitate plasticisers have become the first choice for high temperature applications, such as for wiring that will be used in close proximity to vehicle engines.

Phosphate ester plasticisers are more commonly used in applications where flame-retardant and smoke-suppressant properties are important.

Polymeric plasticisers are ideal for use in cables where oil resistance is necessary or where plastics susceptible to stress cracking can make contact with the cable.

Versatility

By varying the quantity of plasticiser, manufacturers can select precisely the degree of flexibility necessary to meet the mechanical requirements of the end application. Road vehicles, for example, need very different wiring to household appliances.
Furthermore, the equipment used by wire and cable producers - although sophisticated - does not demand high levels of investment.

Consequently, using plasticised PVC guarantees a compelling ratio between cost and performance.