With pbc polymer ag’s STAR and OPTI TPE material ranges, virtually the entire spectrum of applications is covered.
|Mechanics||very good elastic and mechanical properties||good elastic and mechanical properties|
|UV/ozone||excellent weather resistance||excellent weather resistance|
|Resistance||excellent longevity, good resistance to water, acids and alkalis, good paint and colour compatibility||excellent longevity, good resistance to water, acids and alkalis, good paint and colour compatibility|
|Temperature||-50 to +120°C||-50 to +100°C|
|Applications||Machinery and plant engineering
Medical and food sectors
|Building for doors, windows, façades and conservatories
Medical and food sector
pbc polymer ag’s range of silicone materials covers practically the entire spectrum of applications.
Silicone - VMQ
|Mechanics||limited mechanical properties|
|UV/ozone||very good weather resistance|
|Resistance||good resistance to ageing and chemicals, good resistance to corrosive air pollutants, good paint compatibility, even with aqueous acrylic dispersions|
|Temperature||-70 to +200°C|
|Applications||Building, transport and vehicle sectors
Household appliances such as fridges and ovens
Medical and food sectors FDA / KTW / BfR
Silicones consist of individual siloxane units. Those silicon atoms that do not reach their octet (electron shell) by forming bonds with oxygen are saturated with organic residues.
The composition of the siloxane unit is given taking into account the fact that each oxygen atom forms a bridge between every two silicon atoms: RnSiO(4–n)/2 (n=0, 1, 2, 3), i.e. a siloxane unit may have one to four further substituents, depending on the number of remaining valences on the oxygen. Siloxane units can therefore be mono-, di-, tri- or tetrafunctional. In symbolic notation, this is represented by the letters M (mono), D (di), T (tri) and Q (quatro): [M]=R3SiO1/2, [D]=R2SiO2/2, [T]=RSiO3/2 and [Q]=SiO4/2. A network constituted of Q units would correspond to quartz glass.
As with organic polymers, the multitude of possible compounds is based on the fact that different siloxane units can be linked together in the molecule. Based on the systematics of organic polymers, the following groups can be distinguished:
- Cyclic polysiloxanes are ring-shaped and comprised of difunctional siloxane units. Structure [Dn].
- Linear polysiloxanes with the structure [MDnM] or R3SiO[R2SiO]nSiR3 (e.g. Poly(dimethylsiloxane))
- Cross-linked polysiloxanes in this group are chain- or ring-shaped molecules linked by way of tri- and tetrafunctional siloxane units into planar or three-dimensional networks. For the construction of high-molecular silicones, chain formation and cross-linking are the dominant principles.
- Branched polysiloxanes that have trifunctional or tetrafunctional siloxane units as branching elements. Structure [MnDmTn]. The branching point(s) is/are incorporated either in a chain or a ring.
Silicones can be further classified according to the substituents bonded to the silicon. The siloxane backbone may contain various hydrocarbons, and silicon-functional and organofunctional groups may be present. A division into non-functional, silicon-functional and organofunctional is therefore expedient.