Condensation-curing silicone rubbers

During the curing of condensation-curing RTV silicone rubbers, a volatile substance is released: ethanol/propanol. Optimum properties can be obtained by post-curing the rubber at a high temperature (up to 150°C) after curing so that the by-products can remove themselves from the rubber.

Condensation-curing systems are mainly used for making flexible moulds with a complicated surface texture. The silicone rubber is resistant to castings from polyester resin, polyurethane castings, polyurethane foams, plaster and wax. Characteristics compared to addition-curing systems are:

• Curing time cannot be accelerated by adding additional heat.

• Curing not sensitive to inhibition.

• Cured rubber can depolymerise when heated to high temperature (> 250 º C) in an enclosed environment.

• Condensation-curing silicone rubbers have low shrinkage, but higher shrinkage than addition-curing silicone rubbers.

Romar-Voss Composites' product range includes the following condensation-curing silicone rubbers.