A Second Life for EPDM

EPDM is a synthetic rubber used, among other things, for seals in washing machines and car doors, as well as for technical elastomer components. Until now, such materials have often been incinerated or processed into rubber powder after use. In the process, valuable material properties are largely lost.

The “MoRE” project takes a new approach: sorted EPDM seals are processed into reusable materials. In particular, used car door seals are shredded and processed into a granulate suitable for further processing.

Devulcanization for New Applications

In the next step, the material undergoes continuous thermomechanical devulcanization. This partially breaks down the rubber’s chemical network structure. The resulting devulcanized EPDM material (rEPDM) can then be reused in new products.

The Fraunhofer Institute for Chemical Technology ICT is developing a continuous process for this in a twin-screw extruder. In addition, process intensification using microwaves and ultrasound is being investigated. Intensive degassing is also intended to reduce unpleasant odors.

New Seals and Technical Components

The Fraunhofer Institute for Structural Durability and System Reliability LBF is preparing rEPDM material for new elastomer products. Through re-vulcanization, the recycled material is to be processed back into durable elastomer components.

Applications include, for example, new seals, technical rubber molded parts, and vibration and damping elements. The goal is to achieve 80 to 100 percent of the level of virgin material in key mechanical properties.

Interesting for Plastic Products as well

The Fraunhofer Institute for Environmental, Safety, and Energy Technology UMSICHT is pursuing another approach. There, rEPDM is further processed into so-called core-shell particles and used as an impact modifier for polypropylene (PP).

This could make the recycled material attractive for technical thermoplastic products as well. With a recycled content of 20 to 40 percent, the core-shell particles improve the impact resistance of PP, allowing the plastic to be used in demanding technical applications.

On the Home Stretch to Industrial Application

In the final phase of the project, the primary focus is on transferring the developed processes to industrial applications. The results are of particular interest to manufacturers and recyclers of household appliances, seal manufacturers, and companies in the automotive, plastics, and elastomer industries.

The initial results of incorporating the devulcanized material into both new elastomer products and as an impact modifier in PP are promising.

“MoRE” thus demonstrates a way in which used EPDM gaskets can not only be recycled but also returned to the material cycle as a raw material for new, high-quality gaskets and technical plastic and elastomer products.