Stanyl is the first high-temperature polyamide and the only aliphatic polyamide in its class. Thirty years ago it defined this class of materials and today it is still the most widely used polymer basis. The symmetry of the 46 structure ensures that the polymers fit in the crystal in multiple ways, thereby giving rise to high crystallization speeds and high crystallinity. This combination makes the material ideal for high-temperature applications due to excellent mechanics as well as wear and friction behavior, where the flow and the flow-mechanics balance are one of a kind.
The unique stabilization technique developed in house at DSM has sparked the Diablo portfolio. This class of materials have improved heat ageing performance versus the standard-heat stabilized materials.
A wide range of PA46 materials have been developed that can be applied in friction driven applications, like gears, actuators and valve timing chain guides.
Due to the superior flow behavior, high CTI, strong mechanical performance at high temperatures and weld-line strength, Stanyl is often used in connectors, for example USB-C connectors.
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.
TENSILE IMAGE
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.
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The first commercializations of Stanyl were achieved 30 years ago. Currently, it is the largest single polymer being used in the high-performance polyamide landscape. The symmetry of the chemical structure lays the foundation of its success as it provides the basis for the high degree of crystallinity and fast crystallization speed. These two features are the basis of the three key strengths of Stanyl being excellent high-temperature mechanics, excellent wear and friction performance and superior flow. These strengths are what drives the business of Stanyl. Because of these features, this materials displays exceptional retention of mechanical properties after passing through the glass transition, giving rise to its high-temperature performance.
Sintered metal gears are being replaced with high-performance plastic gears in automobiles because the demand to lightweight vehicles and increase fuel efficiency is far from just a trend—it is driven by meeting new and upcoming legislation to reduce emissions.
As consumer acceptance of electric vehicles continues to rise, the need for equivalently advanced material solutions in growing. DSM offers a wide range of product portfolio which addresses these diverse needs.
Join this 30-minute webinar and learn which metal components can be replaced with plastics now and in the future. Presenter: Bert Havenith, Strategic and Market Intelligence Director, DSM Engineering Materials
