Properties for injection molding grades
Akulon is ideal for injection molding thanks to its unique combination of temperature considerations, mechanical performance, thermal qualities and chemical resistance.
Akulon polyamide 6 has a continuous-use temperature of up to 185ºC: In fact the chart below shows that polyamide 6 delivers better long-term performance at high temperatures than polyamide 66 and should be the preferred material for any application running for extended periods above 150ºC.
With superior end-of-life properties of up to 60%, polyamide 6 can be used at the design stage, either to reduce the amount of material needed, or by extending durability or part life guarantees.
Polyamide 66 is preferred where temperatures spike at above 215ºC (the HDT of glass reinforced polyamide 6) but less than 250ºC. For even higher temperatures, a material like our super heat-resistant Stanyl® polyamide 46 is ideal - for example in part fabrication where secondary processing under high temperatures happens (like soldering in electrical applications).
In hot water environments of 100ºC+ polyamides can suffer from hydrolysis - especially around glycol (as anti-freeze additive). The hydrolysis rate is determined by the amount of water absorbed, and 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.
As well as performing well, Akulon polyamide 6 also looks good, compared to 66 it delivers easier on-line coloring where the color mixes more readily to provide a uniform, streak-free colored part.
Akulon polyamide 6 also delivers better part appearance than polyamide 66 when using reinforced grades: Easier flowing materials mean smoother, resin-rich surfaces enabling splay or flow lines to be eliminated. The result: Quality parts that don’t require painting.
Finally, the slower crystallization of polyamide 6 means the material doesn’t freeze off as quickly, which makes for a better surface appearance - especially in reinforced grades - with no orange peel effect
Polyamides are renowned for their resistance to a wide range of chemicals. Our Akulon and Akulon Ultraflow polyamides deliver excellent resistance to different types of oils and grease and are ideally suited to under-the-hood applications like engine covers - as well as gears and bearings for industrial applications.
Akulon, like other polyamides, is attacked by strong mineral acids and is susceptible to hydrolysis around water and glycols at elevated temperatures unless stabilized. So how do you choose an Akulon grade with respect to chemical properties?
- Versus polyester (PBT): Better hydrolysis resistance and resistance against alkaline solvents
- Versus poylcarbonate (PC): Better environmental stress crack resistance
- Polyamide 6 has better heat aging and oil resistance than polyamide 66
- Polyamide 66 has better hydrolysis resistance for grades with similar glass fiber content to polyamide 6.
Akulon performs over a wide temperature range. Unfilled and reinforced materials can be used for demanding engineering applications from as low as -40°C (-40°F) to just below the melting point of the polymer: 220°C (428°F) in the case of polyamide 6 and 260°C (500°F) for polyamide 66.
The high crystallinity and melting point of Akulon enables these materials to retain stiffness at elevated temperatures. For critical applications, this means better safety margins, and thinner walls compared to other materials.
When it comes to measuring properties after aging, we recommend this is best performed under real conditions in the application itself. So for automotive applications where peak temperatures remain under 180°C (356°F), polyamide 6 provides better heat aging resistance and improved security and durability compared to polyamide 66.