THE ENDLESS POSSIBILITIES OF RUBBER
Silicone Rubber, VMQ/PVMQ
Dow Corning (a joint venture between Dow Chemicals and the Corning Glass Company) first produced silicone
rubber in 1943. General Electric followed with the production of silicone rubber in 1947. They patented their production method.
|Resistance and properties:|
The rubber with the largest temperature range (-100 deg C (phenyl silicone rubber) up to more than +300 deg C). Superior ageing and ozone resistance, high electrical insulation values. Broad scale of chemical resistances. Good compression set at higher temperatures. PVMQ especially resistant to high energy ionising radiation. Its mechanical properties are not highly regarded, although this does not have to be the case. The tensile strength of silicone may not exceed around 11 MpA at room temperature. If desired, there are other elastomers with higger tensile strength. However, if temperatures are higher we see the values for other elastomers decline. At these higher temperatures, the values of silicone rubber remain much more constant. In addition we have silicone compounds with extremely high tear strengths for silicone rubber. As a result of its high degree of physiological inertness, silicone rubber is also used in food and medical applications. Silicone rubber is also resistant to bacteria and fungi.
Silicone rubber adheres poorly, for example to PTFE. We have been bounding silicone rubber to PTFE for almost 44 years. We can also make silicone rubber flame resistant. When silicone rubber is totaly burned, a white silicium powder remains. We are also able to produce silicone rubber that is an electrical conductor. We are able to make the compound suitable for gas chromatic applications, such as septa, that have to continue to close after a great number of perforations and may not emit any substances that could interfere with the readings measurements.
We are also able to make silicone rubber of extremely low hardness, around 10 deg Shore A.
Poor impermeability to gas, not resistant to hydrocarbon-based fuels, aromatic hydrocarbons (benzene, toluene), low molecular weight silicone oils, strong acids and alkalis. It is regarded as mechanically weak.