Quality Products from Rubber Residues

Photo: Products

Each year throughout the world, up to 22 million tons of rubber are processed and a large portion of it goes into the production of vehicle tires. Once the products reach the end of their useful life, they typically land in the incinerator. In the best case, the waste rubber is recycled into secondary products.

Ground to powder, the rubber residues can be found, for example, in the floor coverings used at sports arenas and playgrounds, and in doormats. But until now, the appropriate techniques for producing high-quality materials from these recyclables did not exist. Researchers at the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany, recently succeeded in optimizing the recycling of rubber waste materials. They have developed a material that can be processed into high-quality products, like wheel and splashguard covers, handles, knobs and steerable castors.

The new plastic compounds are called elastomer powder modified thermoplastics or EPMT for short. They are comprised of rubber residues crushed into elastomer powder that are blended with thermoplastics. “In the first step, the rubber residues – that can be meter-long rubber pieces are granulated to three-millimeter large particles. The particles are cooled with liquid nitrogen and then ground into elastomeric powders. This is then conducted to the melt-mix process with thermoplastics and additives. Here we use, for example, polypropylene as a thermoplastic material,” as Doktor Holger Wack, scientist at UMSICHT, explains the production process. Working jointly with his colleagues Damian Hintemann and Nina Kloster, the trio collaborates on the “EXIST Research Transfer” project sponsored by the Federal Ministry for Economics and Technology BMWi, where they work meticulously on various recipes for new blends of materials that are already protected by patent and trademark rights.

The compound stands out from a number of different perspectives: The crushing of rubber waste is more environmentally-friendly and resource-efficient than producing new rubber products – an important aspect in view of the rising costs of energy and raw materials. “EPMT may contain up to 80 percent residual rubber; only 20 percent is made up by the thermoplastics,” says Wack. EPMT can be easily processed in injection molding and extrusion machines, and in turn, these products are themselves recyclable. The clou: The physical and mechanical material properties of the substance – like elasticity, breaking strain and hardness – can be individually modified, according to the customer’s wishes.

COMPAMED.de; Source: Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT