Butyl: The polymer butyl (IIR - isobutylene isoprene - rubber) is an elastomer with a small number of double bonds, produced through co-polymerisation of isobutylene and isoprene.
EPDM: The polymer EPDM, ethylene-propylene rubber, is produced through co-polymerisation of ethylene, propylene and diene monomer, producing a polymer made up of saturated linear macromolecules with a paraffinic structure.
In addition to the base polymer, both EPDM and Butyl contain reinforcing carbon black, fillers, process chemicals, antioxidants and vulcanising agents. After mixing the ingredients into a homogenous plastic compound, two layers of the rubber are rolled out in a calender to form a double sheet. Vulcanisation is then carried out. The long rubber molecules in the material are cross-linked through heat and pressure, creating an elastic membrane.
RESISTANT TO THE ENVIRONMENT
The vulcanisation process means that the material differs from all thermoplastic products, in that its properties are not affected by varying temperatures. The product is chemically stable and always returns to its original dimensions after stretching.
The cross-linked molecular structure gives EPDM and Butyl rubber their unique properties. Ageing or changes in characteristics are negligible despite decades of exposure to the atmosphere, sunlight, UV radiation, chemical fallout, water or major temperature fluctuations.
