Bits of clay improve TPO properties
Thermoplastic olefin (TPO) nanocomposites, which use nanometer-sized clay particles as a reinforcement, have so far been discussed more than molded. But General Motors, Blackhawk Automotive Plastics, and Basell Polyolefins recently used this emerging materials technology in a commercial application—the step-assist (running board) for the 2002 GMC Safari and Chevrolet Astro. "This is the first automotive exterior application for a TPO nanocomposite," notes Mark Bennett, Blackhawk's advanced technology manager. TPO nanocomposites offer some compelling benefits. Bennett reports that the new materials are about 15% lighter than conventional talc-filled TPO grades. "The nanocomposites are also stiffer, less brittle in cold temperatures, and easier to recycle," he adds. And they can be formulated with shrink similar to talc-filled TPO, allowing them to run in existing TPO tooling. "They can be a drop-in replacement for talc-filled which was important in this initial program," he says. Future projects will likely take greater advantage of the design possibilities provided by a stiff, light material. Blackhawk has started working on another exterior application and is helping evaluate an interior instrument-panel component for GM, which has exclusive rights for two years. Basell Polyolefins : Enter 515
Nylon gives tanks utility, looks
In outdoor power equipment, "see-through" is a quality that's more practical than fun. Tanks made from see-through plastics let operators check the fuel and oil levels. "And they look much better than opaque gray tanks," says Jorge Theresin, production control manager for Stihl Inc. "Looks really count in our market." Yet not all translucent plastics have enough fuel resistance or strength to hold up to the hard use they will see out on the lawn. DuPont has introduced a new Zytel nylon that balances these competing needs. Called FE5322, this new material is translucent, yet it has mechanical and physical properties similar to traditional glass-reinforced nylon 66. Stihl recently used the new nylon to create tanks for its 420 Series of commercial backpack blowers and sprayers. The company injection molds two tank halves and vibration welds them together for the finished product. Theresin points out that the nylon had to be reinforced to eliminate a leak path around the filler cap, which screws into internal threads in the tank. "A snug fit is essential, so we need an exceptionally rigid tank construction material that resists flexing when subject to vibration forces," he says.
DuPont Engineering Polymers : Enter 516
Rotomolded color charges ahead
A new antistatic technology from Teknor Color Company takes aim at the swirling color defects that once hurt the cosmetics of rotomolded parts. These swirls, and streaks also result from static electricity generated by friction between the powdered plastic resin and the rotating mold, explains Harry Howard, Teknor's director of R&D. The company's patented H2Stat technology uses an inherently conductive additive to dissipate static charges. It's suitable for both organic and inorganic pigments and a variety of resins—including PE, PP, PC, and nylon. The use of an inorganic additive sets H2Stat apart from previous static fighters, which use organic compounds to draw a bit of charge-dissipating moisture from the atmosphere. Unlike traditional antistatic treatments, atmospheric conditions don't matter to H2Stat. So it could help more rotomolders deliver swirl-free parts. "For molders in very dry climates, the technology is the first effective solution to static build-up," says Howard. The first user of the new technology, however, doesn't normally worry too much about moisture: Swimways Corp., a Virginia Beach, VA-based maker of leisure products, recently used H2Stat to produce pontoons for a swimming pool lounge.
Teknor Color Company : Enter 517