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RheTech's RheVision natural fiber families include coconut fiber, flax fiber, wood fiber, and rice hulls (shown).

Growing interest in bio-based material parts

Plastic composite parts outnumber bio-based material vehicle applications, but “green” projects are making inroads by overcoming various hurdles.

“The primary challenges to using bio-based materials, as with any new materials, are meeting or exceeding the cost targets and the performance characteristics of the incumbent material,” Valerie Sathe Brugeman, Senior Research Project Manager in the Sustainability and Economic Development Strategies Group at the Center for Automotive Research (CAR), noted in an interview with Automotive Engineering.

Brugeman moderated the “Bio-Based Materials: Ready For Mainstream?” panel discussion on December 4 at Schoolcraft College’s VisTaTech Center in Livonia, MI. It was CAR’s first event on the bio-based material topic, underscoring the auto industry’s interest in making vehicle parts from sustainable materials.

Prior to the Great Recession of 2008-2009, RheTech Inc. executives had a strong motivator for diversifying the privately held firm’s portfolio. “We felt that we had to get into the bio-renewable segment because non-renewable materials aren’t going to be around forever,” said James Preston, RheTech’s Vice President of Strategic Growth.

The Whitmore Lake, MI-based company, a provider of filled and reinforced polypropylenes, engineered resins, color concentrates, and additives, spotlights sustainable materials via its RheVision portfolio of bio-fiber-reinforced thermoplastics.

“The majority of our bio-fibers are true waste products. They are not grown for us, nor do they take away from food production,” Preston said.

Certain natural fibers (ground rice hulls, ground wood fiber, and flax fiber) match up very well to the properties of traditional ground-mineral-reinforced polypropylenes. However, natural fibers fall short in tensile strength compared to glass-fiber-reinforced polypropylenes.

“We’ve done a great deal of work with Dow Corning on an additive that could increase the tensile strength of these natural-fiber materials. We’re completing our commercial trials and should have the results in the second quarter of 2015,” said Preston.

Focus on interiors

Plastic composite material parts are a vehicle interior mainstay, but the door is open for bio-based materials usage. Rose Ryntz, PhD, Senior Director of Advanced Engineering and Material Development, North America for International Automotive Components (IAC), pointed out that “virtually every interior component can be made of bio-content material.”

IAC’s interior portfolio includes parts made from bio-based materials, such as the natural-fiber-based door bolster used on the current Ford Escape utility vehicle.

“We’re about to test prototype parts made with carbon fiber and the natural fiber, kenaf,” said Ryntz. A door bolster made of carbon fiber and kenaf is expected to provide a 35% to 50% weight savings in a production application. “IAC produces compression molded parts made from natural fibers that are 3 mm thick, but those parts could drop to 1.5 mm to 2 mm in thickness because of the stiffness provided by the carbon fiber,” Ryntz said.

Carbon-fiber/natural-fiber door bolsters are planned as a cost-neutral counterpart to natural-fiber door bolsters.

Henning Karbstein, BASF Corp.’s Manager of New Business & Idea Management for Dispersions & Formulation Additives in North America, said that the North American market typically expects a short-term return on investment without a performance compromise from a natural-fiber composite solution. Paying a “premium for a green solution is mostly not accepted,” said Karbstein.

Ford collaboration pursues tomato-based composites

A Ford team is looking for green material solutions, a task that matches the sentiments of auto pioneer Henry Ford. “He had a vision that the farmer and the automaker each produced what the other needed,” said Ellen Lee, PhD, Team Leader of Plastics Research at Ford Motor Co.

The team’s key research areas are bio-based and sustainable foam development, natural fibers for reinforcement of composite materials, bio-based resins, and recycled materials. Their R&D work is being enhanced by a unique industry-to-industry partnership, the Plant PET Technology Collaborative (PTC).

Ford, The Coca-Cola Co., H.J. Heinz Co., Nike Inc., and Procter & Gamble formed the PTC strategic working group in June 2012. “We’re sharing a lot of information that doesn’t really affect our competitive advantage,” said Lee, noting that various production processes are being evaluated from lifecycle assessment and other perspectives.

One notable outgrowth from the collaboration deals with finding a viable automotive application for a tomato processing byproduct.

“Heinz processes millions of tons of tomatoes every year to make their ketchup products. Some of the leftover tomato pomace goes into pet food, but for the most part there is not a big value-add use for the pomace; it’s a waste product,” Lee told Automotive Engineering.

Ford researchers have been mixing the pomace with plastic resins to make composites. Explained Lee, “Because we have many different types of composites that need to meet different requirements and functions, we think we can find an area to use it. We’re still in the materials development phase, but we’re starting to reach out to the supply base, looking for compounders that can help develop formulations for the materials.”

The ability to use tomato pomace as a feedstock for making storage bins, wiring brackets, or other automotive components looks promising, but there are challenges.

“One of the hurdles is cost. Even though it’s a waste product, there is a cost if you have to dry the tomato skins. And if you have to transport the pomace, that adds cost,” Lee said.

Sustainable supply chain

Growing renewable resources near the supply base is a transportation cost saver, but there are many factors affecting the sustainable materials supply chain, noted RheTech’s Preston.

“A lot of companies may not be able to find some of the vendors we did,” said Preston. “We’re working with the largest walnut producer in the United States, and about two and a half years ago they set up an operation to grind the shells.”

RheTech uses the walnut shells as reinforcement for certain polypropylene compounds.

IAC’s Ryntz agrees that access to crops and other bio-based resources is one of several stepping stones toward vehicle implementation.

“The big thing when you’re talking natural products is where do you get them? But just as important is the growing season, the sorting process, and the type of ancillary processes that are needed to assure the quality control specifications,” said Ryntz.

Preston expects bio-based consumer goods to grow at a faster rate than automotive uses over the next 10 years.

“Automotive OEMs and Tier 1s are definitely looking at bio-based material applications; some are more purposeful than others. Ford and Hyundai, for example, have very aggressive programs to get natural fibers in place,” said Preston. “We believe it’s just a matter of time before more companies jump on the bandwagon as automakers understand the capabilities of natural fibers.”

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