An improved grade of polyphtalamide overcomes the material's inherent brittleness, giving extrusion processors the ability to use the material to replace metal in automotive engine compartment tubing applications.
The new grade, Rilsan HT, was developed and is supplied by Arkema (Philadelphia, PA). Polyphtalamide (PPA) has been used for years in high-temperature automotive applications, but almost exclusively for rigid molded parts. Arkema reckons Rilsan HT is the first PPA-based extrusion grade that can replace metal in tubing for severe engine-compartment service and other demanding industrial applications. The material even has 'green' credentials as it largely (up to 70% of its carbon content) is derived from renewable non-food-crop vegetable feedstock—castor beans.
According to the supplier, the material brings with it top-notch long-term resistance to thermo-oxidative and chemical aging at high temperatures. Arkema says that not only did it overcome the material's inherent brittleness with this grade but that it also managed to ensure it would have low moisture uptake, so that parts extruded from it are dimensionally stable.
Arkema says the material already has been specified for metal replacement in engine-compartment tubing applications. It has also been selected for powertrain applications, including oil transport, exhaust gas recirculation and blow-by lines. Based on these applications, system cost savings up to 50% are seen as possible when metal is being replaced. Rilsan HT processes on standard extrusion equipment and also is thermoformable.
Glass-fiber-reinforced and conductive grades for injection molding also are available, suitable for processing on standard injection molding equipment with conventional water-cooled temperature control using injection molds designed for PA11 and PA12. Rilsan HT can be spin-welded with aliphatic polyamides, which Arkema says is a new feature for PPA. —[email protected]