Cure systems for silicone
Silicone fluids can be used "as supplied." In other words, their
properties are fully developed. Silicone gels, elastomers, and resins, however,
may need to be crosslinked (or cured) to achieve their final properties. This
requires the presence of a crosslinker – a silicone molecule with multiple
functional sites that can react or link with another silicone polymer.
Under the right conditions (heat, humidity, or ultraviolet
light) – and in the presence of the crosslinker and a catalyst – the individual
polymer chains will link together to form a more complex material.
Depending on the base polymer, the crosslink density, and the
presence of any reinforcing fillers, this material can range from a rigid film
to a flexible rubber or a spongy gel.
Crosslinking or cure reactions for silicones
There are three crosslinking reactions for reactive silicone
A peroxide-initiated free radical reaction, which is activated by
A condensation reaction, which takes place in the presence of a tin
salt or titanium alkoxide catalyst
An addition reaction, which is generally catalyzed by a platinum or
For an in-depth discussion of silicone crosslinking reactions, read Section
5 of the Silicone
Chemistry Overview. (PDF Size 210KB)
|One- or two-part cure systems are selected based on the
environment they will be used in, the method of application, the expected rate
of use, and other application requirements. Compare the typical uses,
advantages and disadvantages of one- vs. two-part
silicone cure systems.