Appliance Design - August 2007 - (Page 29)

These pellets from PolyOne are used in the company’s NanoBlend nanocomposites. PLASTICS 14.0 12.0 10.0 Log (Resistance) q Surface Resistivity Volume Resistivity 8.0 6.0 4.0 2.0 0.0 A B C D E Increasing CNT Weight Percent An example of the CNT- Percolation curve from RTP Co. As carbon-nanotube material is added, the resistivity is changed. composites offer tremendous benefits over standard materials. Initial testing of DuPont’s DNM product for instance illustrates the point. In one test, the addition of 1.5 percent by weight of DNM in glass-reinforced PET material produced improvements in heat deflection temperature (HDT) of 10 DegC to 15 DegC over typical glass-reinforced PET (see chart). Since that introduction, Rao says that the company has made significant progress understanding the properties attainable as particle size is reduced and a “greater interfacial area” is generated. He added that significant improvements in crystallization, rheological, mechanical, and permeability properties can be achieved for improved processing, better structural performance, higher heat deflection temperatures, better electrical insulation and improved barrier to gas permeation. formation of a stable char. Testing by NIST and other groups has shown that the materials decrease peak heat release rates. The barrier properties offered by nanoclay compounds is one reason that RTP Co. chose this type of material for fuel system applications, which have stringent barrier demands. “The new nanoclay compounds can provide a monolayer solution for small engine and fuel tank manufacturers to meet the new fuel emission standards for recreational vehicles and lawn and garden equipment,” says Sam Dahman, product development engineer at RTP. He says that the nanocomposites performance is due to “large aspect ratio layers creating an extremely tortuous path for diffusion.” Another unique nanoclay material is called NanoVin produced by European-based SolVin. This nanocomposite combines polyvinyl chlo- Calling on clay To date, nanoclay technology has been more often discussed than nanotubes. A primary reason for this had been the high cost for nanotubes, but that reason is starting to wane as nanotube costs have dropped. Still, nanoclays have their own benefits such as improved barrier properties and flame retardancy. Nanoclay materials are made with clay mixed at small percentages with plastic resins. In one application, the composite is used to produce a transparent film. The compounds offer improved mechanical and thermal properties compared to neat resins. And their low loading levels, in the 2 percent to 8 percent range, increase stiffness with minimal impact on specific gravity. In flame retardancy tests, the clay eliminates dripping and promotes the ride (PVC) and clay nanoparticles. According to Richard Thommeret, marketing manager for SolVin, the initial research was undertaken to improve the stiffness of PVC, but it was discovered that material had viscoelastic behavior. Thommeret says they are targeting coating applications such as mastics and inks where the viscosity behavior is critical. He adds that the material is meant for plastisol application, a mixture of paste PVC with plasticizer enabling the finished product to be soft. The principle of the process is to apply a thin layer of plastisol on a support such as fabric, metal, and glass, Thommeret says. The plastisol material is applied as a fluid and as it contacts the surface to be coated it becomes viscous, sticking to the surface and not dripping. It is then ‘cooked’ to make it homogeneous and fire and impact resistant. The company is working on new versions with barrier properties against moisture, oxygen and carbon dioxide, as the clay material has already demonstrated such improvement in polyamides. Tumbling tube costs Nanotubes, most often made from carbon, also offer numerous benefits. They are infinitely small, but very strong and stiff, says PolyOne’s Jarus. He adds that they are appropriate for use in electrical applications because they are good at electrostatic dissipation. They are also clean systems, says Ned Bryant, a senior product development engineer for the RTP Co. Clean means that they are free from ionic contamination and from out gassing from the plastic over time or from exposure to elevated temperatures. PolyOne offers a variety of nano and nonnano polymers that are used depending on the application. www.applianceDESIGN.com applianceDESIGN August 2007 29 http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - August 2007

Contents Editorial Shipments/Forecasts News Watch A Reed Switch is Simople, yet Versatile, and Designers are Finding New Uses for this Time-Tested Technology A Novel Actuation and Sensing Technology can Register a Light Touch, but Resist Blows from a Hammer Tracing the Source of Noise is Made Easier with Noise Source Identification Methods Appliance Noise can be Annoying, but Designers have Many Material Choices to Help Rein in the Racket Nanocomposites are No Longer a Technology for the Future. These Plastic Materials are Already on the Job A New High-Strength, Low-Density Glass-Microsphere Additive can Improve Plastic Part and Molding Performance A New Electromagnetic Weld/Bonding Process Helps Ensure Long-Term Integrity of Joints in Plastic Parts Snap-Based Technology Eases Installation and Makes Products More Serviceable Two-Part Silicone Adhesives Provide a Rapid-Cure Alternative to Traditional One-Part Silicones Classified DesignMart Advertiser’s Index Association Report: GAMA

Appliance Design - August 2007

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