Polyamide 4.6 (PA4.6) is suitable for continuous use at temperatures of up to 170°C, bringing it close to high-temperature plastics like PPS or PEEK. With its favourable price/performance ratio, this polymer is an excellent option for use at high temperatures. The automotive industry uses PA4.6 a lot because of its high resistance to hot engine oil and transmission oil, even at temperatures up to 150°C. You will find this material in chain tighteners, bearing boxes and clutch parts, and because of its excellent shape stability at high temperatures it is also used in connectors and sensors under the bonnet. The electrical industry also likes to use PA4.6 in items like connectors, ignition coils and electric motors as a replacement for metal. PA4.6 has a high crystallinity and by consequence high wear resistance, which can be increased still further by adding lubricants.
The moisture absorption of PA4.6 is high, i.e. 4.5% at 23°C/50% RH and 13% after saturation in water at 23°C. Thanks to the crystalline structure, there are limited consequences for the dimensions, roughly equivalent to PPA and PA6.6. However, rigidity is impaired significantly under moist conditions. PA4.6 possesses excellent resistance to aliphatic and most aromatic hydrocarbons, but not to halogenated hydrocarbons. Like almost all polyamides, PA4.6 is not resistant to strong acids and alkaline substances. Polar solutions are absorbed, which can cause swelling or softening.
Compared with other polyamides, the mechanical properties of PA4.6 are influenced far less by temperature. In terms of fatigue phenomena, reinforced types come close to the highly qualified PEEK, while resistance to cold deformation is excellent. Electrical resistance decreases sharply due to the high absorption of moisture, so this material is not the logical choice for use in combination with high voltages.