silicone rubber cap

Silicone rubber is an elastomer composed of siliconeaaitself a polymeraacontaining silicon together with carbon, hydrogen,oxygen

Silicone rubber offers good resistance to extreme temperatures, being able to operate normally from −55 °C to +232 °C.

At the extreme temperatures, the tensile strength, elongation, tear strength and compression set can be far superior to conventional rubbers although still low relative to other materials.

Silicone is resistant to hot air, ozone, UV radiation, engine and transmission oils, animal and vegetable fats and oils, and brake fluids.

VMQ also has low resistance to mineral oils. Silicone can be compounded to be electrically resistant, conductive, or flame retardant.

Compared to organic rubbers, however, silicone rubber has a very low tensile strength.  For this reason, care is needed in designing products to withstand even low imposed loads. The material is also very sensitive to fatigue from cyclic loading.