Silicone rubber is an elastomer (rubber-like material) composed of silicone—itself a polymer—containing silicon together with carbon, hydrogen, and oxygen. Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures from -50 °C to +250 °C while still maintaining its properties. It repels water and in terms of tear strength, tensile strength, compression set and elongination in extreme temperatures silicone rubber outperforms conventional rubbers. Can be used as electrical insulator, but most commonly used as a radiator hose. Oils, acids and concentrated solvents can attack the compound.
Polyurethane elastomers are a special compound developed to fulfill specific performance. It has excellent elongination and tensile strength, good abrasin and compression set properties. PU is also reistance to light, ozone and oxidation. Limitations are high temperature and acid, vapor and alkali resistance.