Silicone can be supplied as an oil, grease, sealant, or rubber.
The rubber is typically supplied in one of three forms – a room temperature vulcanisation (RTV) kit, as a liquid, or as high consistency rubber (HCR). In its uncured (un-vulcanised) form, the consistency of HCR silicone ranges from soft putty to cheddar cheese! This is in sharp contrast to most other rubbers, which have a much higher viscosity.
Silicone is resistant to very high and very low temperatures, and so is ideally suited to applications that must perform in the harshest of conditions. This includes engine parts, furnace seals, and components used in outer space!
Phenyl-based compounds have been developed for products in operation below the -55°C which general purpose silicone can withstand. These can be moulded, extruded, or calendered, and offer excellent resistance to temperatures down to -100°C.
High temperature resistant silicone compounds can withstand temperatures of up to 300°C for periods of up to 3 weeks. Temperature peaks above 300°C can be tolerated for very short periods of time but they are not recommended for continuous operation at these temperatures. The effect of high temperatures tends to lead to a hardening and increasing brittleness of the silicone so it loses its elastomeric properties.
Silicone will retain its properties regardless of the weather conditions to which it is exposed.
Wet, dry, cold, hot, or humid, parts made from silicone rubber will also not be affected by ozone or UV.
This has led to widespread use in the construction industry (e.g. coatings, fire protection, glazing seals), and automotive industry (external gaskets, external trim).
In addition to being resistant to rainwater, parts made from silicone are not adversely affected by immersion in seawater. This has enabled diving gear, seals and gaskets on submarines and ships, and components on oil-rigs to have a longer operational life.
Because silicone can be formulated to be electrically insulative or conductive, it is suitable for a wide range of electrical applications, including cable covers, insulating gaskets, conductive gaskets, and keyboard components.
Outstanding physical and mechanical properties are enhanced by exceptional resistance to ageing factors such as oxygen, ozone, humidity and moulds. These silicone compounds can be supplied with a high ash cohesion level if required and low burning toxicity.
Specialist insulating materials resist combustion arc tracking and environmental degradation. As such, they are ideally suited for use with high voltage and power transmission equipment such as insulators, surge arresters, and casing pipe.
Silicone is suitable for use in clean environments as the polymer does not support microbiological growth. This makes it ideal for medical devices.
Joint replacements, tubing, catheters, and all manner of medical devices are manufactured using medically approved silicone. Most processing methods can be used for these devices, provided they are carried out in a suitably clean environment.
As a low taint, non-toxic material, silicone can be used where contact with food is required. Coupled with its high temperature resistance, this makes it an ideal polymer for food moulds, baking machinery components, and vending machine tube. Over the last few years there has also been an increase in the number of household utensils manufactured from silicone rubber. Specific grades of silicone rubber are used widely in the production of baby bottle teats due to their cleanliness aesthetic appearance and low extractable content.