Tech Briefs
Supply/demand for recycling

AES' Santoprene rubber weatherseal is used in the Toyota Vitz glass run channel.

Having the technology to recycle plastics does not mean the science is fully utilized. "The amount of recycled thermoset material is very small — probably less than 1% in production today — because there is no significant supply of scrap material," said Dr. Ken Rusch, Recycling Chairperson for the Automotive Composites Alliance (ACA). "From a technical standpoint, 100% of what we mold today could be recycled. Approximately 20% of thermoset parts are reused at the end of a vehicle's life cycle. Today, thermoset parts — most of which are easily removed exterior parts — actually have more value being reused than being recycled."

The number of parts using recycled content could increase dramatically if scrap supply matched demand. In 1997-98, Dana Corp.'s Plumley Division in Paris, TN, began producing prototype cam covers using recycled thermoset content at the request of an automaker. The trials initially utilized 25% recycled content but eventually focused on 15% recycled content. "When it came time to do the production tools and choose the material, we felt we would literally run out of recycled material six months into production because there was no supply infrastructure in North America," said Dwayne Matthews, Director of Sales and Technology for the Plumley Division. Facing a questionable long-term supply of recycled material, the project ended with the prototype phase. "We understood the design needs for using a recycled content material, but the lack of confidence that the supply would be there and the cost disadvantage associated with this very new reclaim process — although that might have been short term — led us to do the program without recycled content."

As was the case before the trials, Plumley produces cam covers from 100% virgin thermoset material. Shifting from virgin thermoset to a recycled content thermoset for parts production may happen in the future. "We can't say that thermosets are where thermoplastics are in terms of recycling, but I think the industry will drive the suppliers of thermoset material to get to that point of recyclability," said Matthews.

A new recycling option could result if automakers find viability in using ammonolysis, the chemical recycling process for nylon. "The idea of an ammonolysis demonstration unit is to collect information about the recycling process itself and, at the same time, seed the market with recycled material so that automakers can start their qualifying process," said Clint Christian, Marketing Leader of DuPont Automotive's recycling efforts. DuPont's Maitland, Ontario, Canada, complex will open a dedicated ammonolysis demonstration facility later this year. Production of recycled nylon — in small volumes for testing — is expected in 2001. "Currently there's a low percentage of components on automobiles that use a post consumer recycled nylon."

Industry demand is the prompter for devising a chemical recycling process for nylon. "With the present mechanical recycling process, there is no one in the industry who can take all of the impurities out," said Christian. "If the industry wants to use recycled nylon for components like air-intake manifolds and rocker covers, we need a process that can provide virgin-like properties. Ammonolysis is a unique process in that it can take waste streams of nylon 6 or nylon 66 and recreate virgin-like properties."

Troy, MI-based DuPont Automotive has been working on the ammonolysis process for more than five years. "The stumbling block, and the industry is still working on it, is collecting, sorting and identifying the waste stream in a cost-effective way," said Christian. "It's an infrastructure issue. We think we've solved the chemical step. In the future, we could look at multi-purpose chemical processes for handling differing materials as we aim for sustainable environmental solutions." Methanolysis, a chemical recycling process for PET, has been available for some time.

Material matching is a recycling avenue that is grabbing industry attention. "If you have a common platform of materials, when the vehicle is at the end of its life cycle it's easier to recycle because there's a single, compatible material stream," said John Christensen, Marketing Manager for Advanced Elastomer Systems (AES) based in Akron, OH. "There is a trend to move away from using dissimilar materials."

Thermoset composites recycle flow chart.

Weatherseals made of AES' Santoprene rubber, a thermoplastic vulcanizate, are in the same family as thermoplastic polyolefins (TPOs) — a material gaining application momentum in exterior, under-the-hood, and interior applications such as instrument panel skin. Last year, Delphi Automotive Systems received Recycler of the Year recognition from the Society of Plastics Engineers for its 100% recyclable, offal (excess material)-utilizing TPO instrument panel skin. In conventional instrument panel manufacturing, offal and other products are landfilled or sold for select applications.

"Delphi's unique process enables us to produce a two-layered skin: the base containing recycled material and the surface providing the interior color match and texture properties customers expect," noted Dr. Norm Kakarala, Research Scientist for Delphi Automotive Systems Advanced Development Group in Troy, MI. The co-extruded TPO skin debuted on the 1999 Mercedes-Benz M-Class and is also on the 2000 Pontiac Bonneville. Delphi's validated in-plant recycling system permits reprocessing up to seven times without loss of physical properties or performance.

Plastic's recycling evolution is just beginning. "The cost of reprocessing is trivial if scrap parts could get where they need to go for processing and selling to a molder," said Rusch. "Once that reprocessing flow happens, recycled composites content would be cheaper than an alternate material."

Kami Buchholz