Since Stanyl® is the only semi-crystalline aliphatic polyamide operating in the high-temperature field, the comparison with other materials is generally with other material classes, like PPS or semi-aromatic polyamides, referred to as PPA. For clarification, we displayed a PA66 based material to show the differences with other aliphatic polyamides, showing that Stanyl® is uniquely situated in this class of materials. All data shown is based on 30% glass fiber filled materials.
In the graph to the left, the loss modulus of three different materials are displayed—a PA66 (blue), two different PPAs (green and purple), a PPS (red), and Stanyl® (orange) as determined in a dynamic mechanical thermal analysis in tensile mode. The DMTA can be divided into the glass plateau region, below the glass transition temperature, and in the rubber plateau region at temperatures higher than the glass transition temperature. Where in the glass plateau all polymers have a similar modulus being 1-1.5 GPa, it is clear that the real strength of Stanyl® starts at temperatures higher than the glass transition temperature. Here, irrespective of the polymer class displayed in the graph, the modulus of Stanyl® is highest of all polymers.
A similar effect can also be seen for the short-term mechanics testing—in this case tensile performance. Where the difference at room temperature is not that big—at 120°C when comparing the data between PPS, PA66, and Stanyl®—it is already clear that Stanyl® has the highest strength and elongation at break of the different materials. The PPA2 deviates as this material is below its glass transition temperature. However, when the temperature is increased to 200°C, Stanyl® outperforms all other materials displayed in this graph, with Stanyl® having the highest strength and elongation at break of these materials.
The wear depth has been determined for PA66 and Stanyl® PA46. In this case the wear was determined in a gear application where the wear depth as function of the number of cycles was being studied. The wear was determined to be much higher for PA66 materials than for the Stanyl® material. The main elements that are providing this strength is the creep and fatigue performance of Stanyl® versus PA66 based materials. In both properties Stanyl® outperforms the other aliphatic polyamides as the stiffness and strength level in Stanyl® is higher due to the higher degree of crystallinity.
Although the chemical structure of Stanyl® brings the fast crystallization speed and the high degree of crystallinity, it also brings a higher degree of water absorption than other aliphatic polyamides. Naturally this absorption of water negatively impacts the dimensional stability of Stanyl® materials and especially for unfilled materials as it contains the highest amount of polymer. Consequently, for the highly filled materials that have a high glass fiber or carbon fiber loading, the water absorption is much lower and the impact on the dimensional stability less severe.
The second effect that moisture has on any polyamide is the lowering of the glass transition temperature (Tg). The moisture absorption for Stanyl® is the highest and the drop-in glass transition temperature is higher, yet Stanyl® starts with a Tg that is 15°C higher than that of PA66. For some applications, this is an issue; however, in cases where the application is operated at a moist condition and at a moderate temperature (40-100°C) the benefits of a high crystallinity level for Stanyl® start to kick in. In this area, the mechanical performance of Stanyl® is higher than PA66.
By using different types of additives, the good electrical properties and the high mechanical performance can be combined in thermal conductive materials.
