Silikonikumi

Silikonikumi, also known as silicone rubber, is an elastomer based on siloxane polymers, which consist of alternating silicon and oxygen atoms with organic groups attached to silicon. The Si–O backbone provides high thermal stability, chemical resistance, and electrical insulation. Silikonikumi is typically crosslinked to form a three-dimensional network, and the degree of crosslinking determines its hardness and elasticity.

Two main families are used: high-temperature vulcanized (HTV) silicone rubber, cured by peroxide or platinum-catalyzed crosslinking, and liquid silicone rubber (LSR), which is cured by platinum-catalyzed addition or condensation processes. The most common base polymer is polydimethylsiloxane (PDMS), though other siloxane backbones exist. Fillers, reinforcing agents, and pigments adjust properties such as hardness (Shore A), tear strength, and color.

Key properties include outstanding heat resistance (often usable above 200 °C, with some formulations up to 300 °C), weathering and ozone resistance, low surface energy, chemical inertness, and flexibility over a wide temperature range. Processing methods include extrusion and molding for HTV and LSR, with injection molding common for LSR parts.

Applications span seals and gaskets, automotive and aerospace components, electrical insulation and potting, medical devices and tubing (including biocompatible grades), kitchenware and bakeware, molds, and adhesives. Medical-grade silicones are particularly valued for biocompatibility and sterilizability.

Safety and environment: silikonikumi is generally chemically inert, but curing and processing can release volatile byproducts; handling catalysts and solvents requires proper controls. They are not readily biodegradable, and recycling options are limited, often relying on energy-intensive processing or mechanical recovery.