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.