Silicones: Characteristics
Flexible from deep frost to engine heat
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Silicones are bought by viscosity (fluids), hardness and tear strength (rubbers), cure system and adhesion (sealants) and purity (electronics and medical). Thermal stability, low surface tension and electrical insulation are the properties that make them hard to replace.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Service temperature | about -50 C to 200-250 C (indicative) | Seals and potting near engines, batteries and lamps | typical datasheet values (indicative) |
| Viscosity of PDMS fluids | about 0.65 to 1,000,000 cSt by grade (indicative) | From cosmetic volatiles to high-viscosity damping fluids | typical (indicative) |
| Dielectric strength | about 18-25 kV/mm (indicative) | Insulators and electronics encapsulation | typical (indicative) |
| Volatile cyclic content (D4, D5, D6) | below 0.1% each in EU-compliant products (indicative) | Regulatory compliance | EU Regulation 2024/1328 (indicative) |
Commercial grades
- DMC and cyclic siloxanes (D4, D5)
- PDMS fluids
- silicone emulsions and antifoams
- HTV gums and compounds
- liquid silicone rubber (LSR)
- RTV-1 and RTV-2 sealants
- silicone resins
- functional silanes
- medical and food-grade elastomers
- thermal interface and potting compounds