Green Machines

Jan. 21, 2005
With worldwide automobile sales expected to more than double in the next 50 years, the drive for waste reduction is accelerating. When specifying materials, product development staffs must now equally embrace design for disassembly and recycling as well a

Concerns about energy use and waste generation are nothing new to the automotive sector. They have been bottom-line issues since the industry's beginnings, and Henry Ford in his 1926 book, "Today and Tomorrow" offered his guiding philosophy: "Industry owes it to society to conserve material in every possible way. Not only for the element of cost in the manufactured article, although this is important, but mostly for the conservation of those materials whose production and transportation are laying an increasing burden on society."

By the second half of the 20th century, the producers' concerns were joined by growing government regulations, and a variety of groups began offering studies dramatizing the finite nature of resources such as energy. It was only natural that governmental policies would initially emphasize improvements in fuel economy and emissions, and the achievements of OEMs in this area are substantial.

Now, global policy makers are shifting towards mandating greater recyclability goals. The good news about recycling is that the metallic content, about 75% of a vehicle, is already recycled via existing infrastructures that perform as profitable business models. The challenge comes from directives from both the European Union and Japan for increasing recyclability above 75%. For example, the European Union's requirement is for 85% recyclability by the end of 2005 and 95% by 2015.

The Plastics Challenge

In a typical vehicle end-of-life context today, 25% remains after parts are recovered for reuse or remanufacture. The dismantling facility then sends this to a shredder for separation into ferrous and non-ferrous metals for recycling.

What's left is non-metallic shredder residue with a growing presence of plastics, says Jim Kolb, director of the American Plastic Council's Automotive Learning Center, Troy, Mich. Kolb estimates that every 100 pounds of shredder residue contains roughly 25 pounds of plastics -- such things as polyurethane foams and polymers along with a fines fraction of metals, metal oxides, glass and dirt.

Kolb's American Plastics Council (APC), reports that 4.19 billion pounds of plastics were used in automobiles and light trucks in 2001. By 2011 APC expects usage to reach about 5.63 billion pounds as vehicle designers choose lighter-weight plastics over heavier materials in order to reduce weight, therefore fuel consumption, and therefore emissions. Citing figures from American Metal Market, APC says usage per vehicle (both cars and light trucks) has grown from 168 pounds in 1977 to 248.5 pounds in 2000. During that time average vehicle weight fell from 3,665 pounds to 3,286 pounds.

The weight-reduction advantage is not the only force driving increased use of plastics in vehicles. OEMs are discovering other performance advantages of hybrid plastic/metal structures that are not available in an all-metal configuration. For example, hybrid front end modules are replacing structures once made of heavy steel stampings and gaining more than 10 times the torsional stiffness according to a study by Bayer Corp., Pittsburgh. In addition, cost benefits accrue from the ability to integrate parts via the molding process. Bayer says plastic/metal front-end structures are rapidly being adopted by OEMs.

But two complications of the increased use of plastics is that not all plastics are recyclable, and a mature recycling infrastructure doesn't exist, as it does for metals.

Partnering For A Solution

Indeed while some cars on roads today contain some recycled plastics, the loop to bring all plastics back into autos again and again is not complete. At General Motors Corp., the concerted effort to consider the use of recycled plastics began in the 1980s, recalls Terry Cullum, director, corporate responsibility and environment and energy, Detroit. In product engineering at the time, Cullum remembers the motivator as being the growing use of plastics to lighten vehicles. The initial challenge was to evaluate the availability of adequate material streams. Initially the company tapped into recycled pop bottles for such things as headliner materials. The high scrap rate for compact disks formed the next supply opportunity for a very high-value polycarbonate material.

"In the early 1990s we joined the Vehicle Recycling Partnership along with Ford and Chrysler to see how the vehicle recycling infrastructure could be optimized. Although metals have a robust economic infrastructure, our challenge is to achieve equivalent results with plastics and fabrics. The goal for a more robust infrastructure for organic materials -- plastics and fabrics -- is part of our research agreement [a five-year agreement signed in 2003] with Argonne National Laboratories and the American Plastics Council."

Recycling plastics raises challenges of feasibility, business infrastructure development and whether the environmental footprint is indeed smaller than the virgin material that is replaced. For example, those factors were involved when a Japanese OEM and a supplier (Toyota Motor Corp. and Denso Corp.) evaluated new technology for recycling Nylon composites from Du Pont and Co., Wilmington, Del.

Du Pont's composite recycling technology is a closed-loop process that is designed to convert parts made of glass- or mineral-filled Nylon 6 or 66 into resin that is essentially equivalent to virgin material.

A variety of parts were evaluated at Du Pont's new Canadian prototype plant at Mississuaga. The feedstock for the development program with Denso consisted of 500 radiator end tanks collected from scrapped end-of-life vehicles in Japan. All of the tanks were made of glass-reinforced Nylon 66. The tanks were dirty and somewhat degraded by age.

Reprocessing began after the tanks were reduced to finely ground particles that were subsequently dissolved at elevated temperatures in a pressurized reactor. Glass fibers and other insoluble ingredients were filtered out, and the next step was to precipitate the dissolved Nylon from the solution. During drying, the precipitated material was heated, inducing solid-phase polymerization to restore the polymer's molecular weight to the same level as that of the virgin Nylon.

The recovered polymer was compounded with glass fibers and compared to the performance of virgin material. Du Pont reports no difference in terms of mechanical properties, resistance to aggressive liquid coolants or molding characteristics. Performance was also similar in terms of high-temperature creep, high-pressure cycling, vibration and low temperature impact.

The studies show that the technology can provide a workable, cradle-to-cradle solution for radiator end tanks, says Du Pont's Bill Hsu, vice president, global technology for engineering polymers. In addition to potentially reducing the amount of materials going into landfills, Hsu says the technology has a smaller environmental footprint and a higher financial return than alternatives that included incineration with energy recovery.

Both Toyota and Denso favorably reviewed test results. Toyota's evaluation involved two identical air intake manifolds -- one made from compounded virgin Nylon 6 -- the other from compounded resin containing 100% recycled Nylon 6. Results of end-use testing for leaks, burst and breaking strength revealed that parts made of recycled content are within specification.

"The technology is very important in helping us achieve our Recycled Vision," says Toyota's Yasushi Miyamoto, general manager, Organic Material Department, Material Engineering Division. "Our vision includes improving the vehicle recovery rate to 95% and developing new technologies that increase to 20% the use of plastic from recycled materials or renewable resources by 2015. We plan to continue to develop this new technology so it can be applied economically in our vehicle recycling initiatives." (See "Toyota's Vision")

Focus On Biomaterials

In 2004 Ford Motor Co.'s vision of the path to sustainable mobility was outlined at the Japan Automobile Research Institute's Next Generation Vehicle Forum. The message to those convened at the United Nations University in Hiroshima seemed to commit the entire global automotive industry. Ford's Ashok K. Goyal, director, product development was the presenter:

"The ultimate goal of producing cars and trucks that emit nothing more harmful than water vapor and use up no finite resource is not only achievable, but will in fact occur because society demands it, consumers say they want it, [and] competition is advancing the necessary technologies to the point that no auto manufacturer can afford to be left behind."

The science of biomaterials will help sustain that direction, adds Paul C. Killgoar Jr., director, environment, physical science and safety of Ford's Research and Advanced Engineering, Dearborn, Mich. He says Ford and the rest of the auto industry are beginning to see an opportunity to replace fossil carbon-based materials with natural-based materials. "We're looking to replace glass fiber with natural fiber such as hemp. We're looking at soy-based foam materials. In addition to enhancing recyclability, biomaterials also offer the environmentally friendly possibility of composting in end-of-vehicle life situations."

Ford's showcases its environmental vision with the Model U, a concept car intended to be as much a watershed for the 21st century as the Model T was for the 20th. First shown to celebrate the company's 100th anniversary, the Model U prototypes a hydrogen-fueled internal combustion engine plus a variety of biomaterial concepts: corn-based tire fillers, engine oil from sunflower seeds, soy-based seat foam and a corn-based compostable fiber sun roof.

The Model U also sports a soy-based resin tailgate that auto buffs will connect with an early 1940s biomaterial project of the original Henry Ford. (Interested in the possible use of agricultural-based materials, the automotive genius tested trunk lids of soy-based composites. One of the publicity photos of the era shows Ford swinging a sledgehammer at a soy-based trunk lid to demonstrate the material's capability.)

Killgoar says biomaterials are already applied to Ford's manufacturing processes to reduce tooling and operating costs. "One example is Canola -- an oil derived from rape seed -- that is formulated as a soluble oil for metal working applications. Both environmentally and user friendly, Canola is low foaming and low misting and can be easily formulated for applications," says Killgoar.

Canola is also being evaluated for possible use in hydraulic oils and lubes, he adds.

Killgoar is enthusiastic about the potential of biomaterials but admits that economic and technical requirements are still to be addressed. One of his examples is the characteristic aroma of soy-based foams: "When you get in your car, it smells like peanut butter. We can't have that!"

He outlined other challenges at the American Chemical Society/Biotechnology Industry Association CTO Summit last October: "fiber-matrix compatibility, increasing fiber flow to eliminate resin rich areas and controlling a tendency of some biomaterials to breakdown in the presence of water. One thing we can't have is the car composting when the person is driving! We need materials that are not composting during the life of the car." At the summit, Killgoar issued this challenge to the chemists: "We're not going to make it until you can prove that it works."

But Killgoar, with 32 years as a research chemist, is confident that biomaterials will be common for automotive applications "before I retire."

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