In general, all silicones (we often refer to silicones as polydimethylsiloxanes) stand out for their high thermal stability, biocompatibility, hydrophobic nature, electrical and separating properties. When silicones are crosslinked to form a silicone rubber, their characteristic properties are still present.
During the production stages of silicone elastomers, many main products and by-products are obtained as output. Silicone rubber group is one of the main products after this synthesis. silicone rubbers; The curing method can classify according to the viscosity of the base polymer. The main classification type is according to the vulcanization system. Here, the classification made according to the vulcanization system also forms the basis for the abbreviations and names given to silicone rubbers. Manufacturers create coding systems in their commercial products according to these abbreviations.
As nomenclature, room temperature vulcanization is RTV (room temperature vulcanization) and high temperature vulcanization is HTV (high temperature vulcanization). RTV systems can be cured at room temperature and HTV systems at temperatures above 100°C. If there is a number in the name, it indicates the number of components that must be mixed to achieve curing, eg RTV-2.
HTV silicone rubbers are mainly solid silicone rubbers. In the uncured state they have a very high viscosity and appear as solids. This behavior has also led to the emergence of the term HCR (high consistency rubber).
In the 1975’s, a new group of materials emerged, intended to be processed in injection molding machines. They were called liquid silicone, LSR (liquid silicone rubber) or simply LR (liquid rubber) because of their low viscosity and paste-like behavior and their fluidity compared to HTV silicones. It is common to use LSR or LR for the abbreviation instead of HTV, even if they are cured at high temperatures as with solid silicone rubbers. The vulcanization and processability of LSR or LR silicones in the injection process is much faster than HTV silicones. Processes in LSR silicones behave like thermoplastics in behavior. This material type is more prone to automation applications as it is possible to achieve lower cycle times. It is possible to achieve fully controllable fast cycles.