Two Main Types of RTV-2 Silicone Rubbers

RTV-2 SILICONE RUBBER Condensation-Curing Systems

Condensation-curing RTV-2 silicone rubbers are composed of a rubber base and a curing agent which contains a tin catalyst. In condensation curing, the polymer chains bond together via a crosslinker and ethanol is released as a by-product. Temperatures exceeding 90 °C before curing is complete result in reversion.

Properties

     RTV-2 grades contain an organo-tin catalyst
     Volatile alcohol by-product released during curing
     At temperatures exceeding 90 °C, reversion sets in
     When heating to boost curing rate, temperature must not exceed 80 °C
     No inhibition of curing
     Weight loss and shrinkage occur during curing (0.2 -0.5%)
     Curing rate can be adjusted to a certain extent by varying the quantity of the curing agent

 
RTV-2 SILICONE RUBBER Platinum Catalyzed Systems

Platinum-curing RTV-2 silicone rubbers are composed of two components, designated A and B. In platinum-curing, polymer chains are linked through a hydrosilylation reaction at the vinyl groups by means of the hydrogen-containing curing agent. Some platinum-curing silicone rubbers are available as ready-to-use one-component products. These are cured by heating to high temperatures.

Properties

     RTV-2 grades contain an organo-platinum compound as catalyst
     No weight loss on curing and very low shrinkage (< 0.1 %)
     No by-products released
     Curing can be accelerated by heating (e.g. 2 min at 200 °C)
     Pot life can be adjusted with platinum
     No reversion of curing
     Curing can be inhibited by certain substances, e.g. compounds that contain amine, sulfur or tin
     One-component materials available