August 09 ElectroIndustry - 17

NANOTECHNOLOGY But nanotechnology is also making its way into old technologies—like wire and cable—in a real and tangible way. Power cables employ jacketing that protects circuit and grounding conductors from mechanical damage Scanning electron transmission microscopy and fire effects. The cable (STEM) STEM Image at 150,000X showing industry uses a number nanoclay dispersion of different materials in its jacketing compounds, including halogens, aluminum trihydrate (ATH) and other fillers to give cable its fire-retardant properties. However, exceeding certain levels of fire-retardant fi llers reduces the mechanical properties of the cable, increases cable density, and leads to poor extrusion during manufacture. In order to counteract these challenges, CONDUMEX-CIDEC (Querétaro, Mexico), together with the Research Center for Applied Chemistry (CIQA) in Saltillo, Coahuila México, investigated ethylene-vinyl acetate-based compounds using nanoclay. The objective was to determine if fire-retardant properties of a polyolefin-based compound would be maintained by substituting some of the ATH content with nanoclay. This particular blend included 43 percent polyolefin, 10 percent nanoclay, and 47 percent ATH. Once nanoclays are introduced into the compound, uniform dispersion is critical. In order to verify that the degree of dispersion was adequate and to verify dimensions, wide-angle x-ray diffraction analysis, transmission electron microscopy, and scanning electron transmission microscopy were used. These tools helped verify that a true nanoproduct was being produced. While these tools can be very expensive because of limited availability, the lack of published standards that govern how measurements are performed on a universal basis is even more problematic. The findings of this investigation were quite favorable. When evaluated according to UL 94, flame-retardant properties were maintained with an 11 percent reduction in ATH. The use of nanoclay compounds also resulted in improved mechanical properties, lower density, and lower viscosity. When compared to standard compounds without nanoclay, this lower viscosity led to 13 percent lower energy consumption during the manufacturing process and a 4 percent reduction in extruder head pressure. New Technologies Yield New Questions Can nanoclay compounds provide similar benefits when used in insulating materials? Will basic insulation properties and mechanical and electrical performance levels be maintained? These questions open new windows of opportunity for the wire and cable industry. Nanotechnology is making its way into old technologies in a real and tangible way As new discoveries in nano-enabled wire and cable products are made, the industry needs to demonstrate that nano-enabled products are indeed nanoscale and that they work the way they should before they become commercialized on a large scale. This is accomplished through IEC TC 113 and IEC end-product committees, where performance assessment methods for nanoscale subassemblies are developed to ensure that they do what they are supposed to do and that they do it for a long time. International consensus standards will enable industry stakeholders worldwide to speak the same language with standard measurements, and allow international commerce to grow. ei 17

August 09 ElectroIndustry

Table of Contents for the Digital Edition of August 09 ElectroIndustry