What is EPDM (ethylene propylene diene rubber), and what are EPDM granules used for?
EPDM stands for ethylene propylene diene rubber, a synthetic rubber made from ethylene, propylene and a small proportion of a diene. The diene provides the reactive sites through which the polymer chains form an elastic network during vulcanisation. Compound formulation and crosslink density can be varied to control hardness, elasticity, heat resistance, low-temperature flexibility and chemical resistance.
The polymer has a largely saturated backbone and therefore contains few ozone-sensitive double bonds. This structure gives EPDM strong resistance to ozone, UV radiation and ageing, properties that are important in outdoor floor coverings. The rubber remains elastic over a broad temperature range and resists water, dilute acids and dilute alkalis. Mineral oils and fuels can, however, cause the rubber to swell.
Unlike recycled tyre rubber granules, EPDM rubber granules are manufactured from newly compounded rubber and through-coloured during compounding. Each granule is consequently coloured throughout its cross-section. In WARCO floor coverings, coloured EPDM rubber granules form the wear layer of two-layer rubber tiles, including patio tiles, balcony tiles and gym tiles. The base layer beneath consists of recycled tyre rubber granules from end-of-life tyres, known as ELT granules.