The inside story. (On Materials).

Looking Beyond the Exterior

While the exterior of the Pontiac Aztek has engendered the use of adjectives by automotive journalists and consumers alike in a way not seen or heard since the days of the Edsel, the interior of the vehicle has actually garnered some praise for its utility (even though Pontiac doesn't call the Aztek a "sport utility vehicle," but, rather, a "sport recreation vehicle").

Part of the inside story of the vehicle is the use of two engineering thermoplastics--a polycarbonate/acrylonitrile-butadiene-styrene (PC/ABs) resin and an ABS resin from Bayer Corp.'s Plastic Div. (Pittsburgh, PA), Bayblend and Lustran, respectively--for the instrument panel (IP) and the knee bolsters. The molding of the components is performed by Meridian Automotive Systems (Dearborn, MI).

Specifically, the IP cluster (which measures 18 x 30 x 9 in.), radio trim plate (15 x 12 x 9 in.), end caps (10 x 8 x 1 in.), and forward extension defroster grille (13 x 50 x 2 in.) are molded with a heat-resistant ABS that is colored with metallic flake colorants, Lustran Elite HH ABS 1827. Heat-resistance is particularly key for the forward extension defroster grille, as it includes the air conditioning vents: think of what cold air might otherwise do to hot ductwork.

The driver-side knee bolster and the glove box assembly are both molded with Bayblend T 85, a PC/ABS blend. The knee bolster consists of two 9 x 20 x 2-in. pieces that are vibration welded to form the assembly. The glove box is assembled from three moldings: an inner and outer, both measuring 10 x 14 x 1 in., and the 12 x 20 x 15-in, box bin. It's said that because the resin provides good impact strength, there is no need for metal reinforcement behind either the bolster or the glove box. That said, however, there are ductile failure properties associated with the material, which would come into play should vehicle occupants collide with the parts during an accident.

Speaking of Unusual Designs ...

Anyone who watched the closing ceremonies of the Sydney Olympics knows that the Aussies are, well, nothing if not imaginative. With that in mind, listen to Sharon Gauci, Ford Australia's Colour and Trim Design Manager: "Leather and faux fur are huge in fashion at the moment, so it is not surprising that they are going to have a big influence in car interiors over the next 12 to 24 months." Faux fur? Gauci says that the material "will be seen in the pile of fabrics used in interior finishes. Fabrics will become shinier, glossier, smoother with a strong brushing and napping effect." And she notes that while the next two years will have colors (or colours) such as camel, dark brown, orange, white, and silver, "Beyond the next couple of years, there will be the emergence of hot acid brights like lime chartreuse and muted, greener versions of chartreuse, industrial grays and colours inspired from liquid sources such as clean, pure bright colour saturations and dehydrated, grayer softer undertones." Sounds like the excess fabric-making capacity for Furbies will be making its way to the auto industry.

As the design brief for Ford Australia calls for a more holistic approach, Gauci is concerned with the exterior, as well. She proposes, "I think you will see more linking of interior and exterior colour and trim of our cars coming onto the market over the next couple of years. We have thought of everything--blending interior and exterior colours, carpets with seat fabrics, wood and other finishes to create a seamless, harmonious transfer from the outside to the inside of the car."

Remember Wood?

Did you ever wonder why the North American auto industry is concentrated where it is? According to James J. Flink in his classic book The Automobile Age (The MIT Press; 1988), "Michigan, Indiana, and Ohio... provided the ideal environment for the manufacture of gasoline automobiles. Their excellent hardwood forests had made these states the center for carriage and wagon manufacturing, and they were also important in the manufacturing of the stationary gasoline engines widely used on midwestern farms. They thus afforded the assembler of gasoline automobiles access to suppliers of bodies, wheels, and internal-combustion engines." While the wood is less important to automotive manufacture right now, Ms. Gauci's comment above causes us to take note of a development taking place at the Fraunhofer Institut fur Chemische Technologie (Pfinztal, Germany, or in North America in Plymouth, MI); a thermoplastic based on lignin and cellulose fibers--a.k.a., liquid wood. Lignin is the material that forms the support structu re for the cellulose fibers in the trunk of a tree. According to the people at Fraunhofer, there are millions of tons of the stuff produced each year as a by-product of paper production. Mixed with other fibers (e.g., flax, hemp), the lignin, processed at high temperature in standard plastic processing machines, can be used to produce various parts with mechanical and thermal properties that are like wood. (Presumably, interior trim parts made with liquid wood would be more wood-like than the faux-wood plastic that is sometimes, unfortunately, used to adorn interiors.) What's more, the lignin-based polymers are biodegradable.