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THERMOPLASTIC ELASTOMER HAS STRENGTH TO HANDLE POSITIVE AND NEGATIVE AUTO ENGINE AIR FLOWS
An airduct, which transports air needed for combustion of fuel in a car, is a complex system that can see either positive or negative pressures, depending on the application. In the case of large diesel engines, an off-engine turbocharger pressurizes (charges) the airflow. In many passenger car applications, the airduct faces negative pressure, as the intake manifold draws air for combustion. Vacuum ducts and charged airducts require chemical resistance to automotive fuels and oil vapors, good mechanical strength under positive and negative pressure loads at elevated temperatures, excellent long-term oxidative aging, and minimal wind noise through the air pipe. In addition, they must be easy to work in secondary manufacturing operations. A new offering in Arnitel thermoplastic elastomer ether ester block copolymer (TEEE) compounds from DSM Engineering Plastics, Arnitel PB582-H, is an ideal choice for airducts due to its combination of these properties. The material enables designers either to specify thinner walls for material and/or space savings, or to retain the as-designed wall thickness and increase performance. It is also blow-mouldable, potentially reducing the number of parts and assembly operations. Arnitel PB582-H is a heat-stabilised, compounded black material with a high level of crystallisation. This crystallisation provides extra performance at high temperatures; the new compound exhibits a 50-60% greater lifetime at any given temperature compared to materials currently in use. Mechanical testing at 150C indicates that weight savings can run to 40% of the original part. The material has been used in Mercedes Benz C-Class automobiles since early 2003 for clean-air(post-filter) ducts. This part’s oval cross-section, dictated by tight under-bonnet space constraints, demands the extraordinary negative-pressure performance shown by Arnitel PB582-H. Side by side comparison in the lab shows also that the sound emission properties of the material - when the parts are in use and therefore hot - is up to 10dB lower. In testing, Arnitel PB582-H doubled heat-ageing performance compared to competitive systems. Arnitel PB582-H allowed for the reduction of wall thicknesses by 20%, saving significant material costs. The material also increased productivity by reducing cycle time by 20%. DSM provided application development and research support, market knowledge, and secondary assembly process support to help make this a successful application. Arnitel from DSM Engineering Plastics is a family of thermoplastic copolyester-based elastomers (TPE-Es or COPE) that combine the strength and processing characteristics of engineering plastics with the performance of thermoset elastomers. As thermoplastics, they do not require vulcanisation to obtain optimal qualities, which often leads to substantial part cost reduction. Relative to other elastomers, Arnitel’s polyester-based materials offer the most consistent performance over their entire operating temperature range since their properties vary little from low to high-temperature extremes. In addition to airducts, Arnitel is used in a broad range of other applications, including automotive constant-velocity (CV) joint boots, airbag covers, radio antennas, and fuel and vacuum hosing; building roofing membranes; surgical disposables; wire and cable insulation; hydraulic hoses; household goods; and light rail insulation and sound deadening.
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