It's back to the future for plastics researchers at Ford Motor Co.
Henry Ford famously unveiled a "Soybean Car" in 1941 at an annual community festival in Dearborn, MI. Fourteen plastic panels strengthened with soy fiber reduced the weight of the car by half. It was never built because focus quickly shifted to military requirements.
Today a six-member engineering team at Ford is looking for new applications for soybeans and other sustainable materials in an industry-leading effort to replace hydrocarbon-based materials.
"Wherever petroleum-based materials exist - in plastic, rubber, foam, film or fabric - we are looking to minimize its proportion and replace it with a sustainable material," says Dr. Cynthia Flanigan, technical expert in Ford Plastics Research.
The group, formed in 2000, has had tremendous success to date. Soy-based foam seat cushions and backs will be used in more than one million Ford, Lincoln and Mercury vehicles by the end of this year, leading to a total reduction in carbon dioxide emissions of more than 5 million lb.
"We started looking at soy-based polyurethane foams in 2001," says Dr. Deborah Mielewski, the leader of the group told Design News in an interview. The first foam produced in the lab had a rancid odor, poor compression set and poor mechanical properties.
"This is where the chemical companies and most of the supply base pretty much ended looking at hydroxylated soybean oil as a component in automotive foams," says Mielewski. "My group had a formulation chemist named Christine Perry who said, ‘I think I can do it.' She went away and made hundreds of different formulations, and the whole point was to balance two reactions: the crosslinking reaction and the blow reaction that makes the cells, and over a two-year period she did it."
The first production model to use the new foam was the Mustang in 2007. It's now used in seven vehicles.
"It definitely has further potential," says Mielewski. "We think we can do headrests. The headliner in the Ford Escape will use soy foam starting this month. We feel it could be used for door arm rests. We can use it anywhere there is urethane foam."
Soy oil is used to replace hydrocarbon-derived oils to make polyols, one of the reactive components that produce polyurethanes.
Soy Flour Reinforcements
"You also get flour or meal from the soybean," says Mielewski. "Now we're studying if we can use that for reinforcement for plastics." That takes the company right back to Henry Ford's demonstration car in 1941. In fact, meal constitutes 82 percent of the soybean.Â
Some of the specific projects at the research department include the following uses for soy fillers:
·      Incorporation of up to 24 percent soy filler in rigid polyurethane foams.
·      Up to 30 percent soy flour can be used in natural rubber. Results to date are positive.
·      Use of soy fillers in EPDM (synthetic) rubber. Ford is collaborating with suppliers on development of actual parts. Results to date are promising.
·      Use of soy as a filler in polypropylene, thermoplastic olefins and thermoplastic elastomers. The soy flour could potentially replace mineral fillers or hydrocarbon materials.
·      Use of soy as a component in automotive paints.
Some of the work on soybean development was funded by a three-year $230,000 grant from the United Soybean Board.
One of the interesting aspects of Ford's research is its emphasis on local crops. Some automotive OEM's are boosting use of polyamide 11 made from castor oil. Mielewski says Ford is not testing the castor oil polymers because its focus has been on local crops.
Another potential local feedstock for Ford vehicles is the Indian grass that grows wild near roads in the Midwest.
"The big motivation in working on natural fiber is a 30 percent weight reduction compared to glass fiber," says Mielewski. "Also, glass fiber takes a lot of energy to produce, and you also get the carbon dioxide reduction because you're sequestering carbon dioxide in the plant when you grow it."
Other natural fibers Ford is studying include hemp, coconut hair (coir) and wheat straw.
"You have probably 10 to 15 different types of plastics on cars and 10 to15 different fibers you might like to use," says Mielewski. "So it's a huge developmental process to find a plastics fiber combination that meets the requirements."
The issue is moisture absorption. "You mold the part and it's lightweight, but over time it picks up moisture," she says.
Natural fiber has been used for years in compression molded seat backs. The new research is looking at injection molding, which takes place at higher temperatures and pressures.
Bioplastics' Potential
Another area of interest, possibly farther out, is use of bioplastics. "The big thing here is their compostability," says Mielewski. That is, after the parts finish their useful life, they are sent to a landfill where they decompose. Current plastics used on cars are theoretically recyclable, but in fact are mostly sent to anaerobic landfills, where they stay for a very long time.
The big technical hurdle is timing the decomposition. "We're looking for switches, such as a microbe that would exist in a landfill but would never exist in the vehicle," says Mielewski. "With a switch, the material won't decompose until it's exposed to humidity, heat, and a microbe."
There's nothing in production yet, but closer may be use of compostable bioplastics for packaging, such as shrink wrap, used by Ford.
Mielewski has three degrees in chemical engineering from the University of Michigan. She'll be the keynote speaker at the SPE Automotive Composites Conference Sept. 15-16 in Troy, MI.
