Hydrolysis critical environments
In hot water environments of 100ºC+ polyamides can suffer from hydrolysis - especially when glycol (as anti-freeze additive) is found (the rate being determined by the amount of water absorbed). Because polyamide 66 absorbs less than polyamide 6, its performance is slightly better. However, for reinforced materials, higher fill levels in polyamide 6 mean grades that deliver the same performance as a polyamide 66, with a lower level of reinforcement. This offers benefits in terms of stiffness, but disadvantages in terms of part weight and design flexibility.
Polyamide 6 has better ductility than polyamide 66. At lower temperatures this makes it a tougher material; less impact sensitive, less notch sensitive and with ductile behavior at lower temperatures. The result: Safer parts (less risk of splintering at low temperatures) and lower breakages levels during processing because parts are tougher coming out of the mold. For unmodified grades where lower temperatures are found, polyamide 6 provides the better performance: Typical applications for this low temperature performance are power tools, ski and snowboard bindings, and automotive exterior parts.