Hello and welcome to a new blog post in which we evaluate the high-temperature performance of PARA (PA-MXD6) vs PPA.
When selecting materials for demanding, high-temperature applications, understanding their mechanical performance under heat is critical. Dynamic Mechanical Analysis (DMA) is a powerful tool for assessing how polymers retain their stiffness as temperatures rise. In this post, we compare the high-temperature behavior of two advanced engineering plastics: PA-MXD6-GF50 (50 wt% glass fiber reinforced Polyarylamide) and PPA(4T)-GF50 (50 wt% glass fiber reinforced Polyphthalamide). Both material fall into the category of semi-aromatic polyamides which reflect a resistance towards higher temperatures. In this post we check if this is the case for the both materials.
DMA Results: Shear Modulus vs. Temperature
Figure 1 presents the dynamic shear modulus (E') of both materials as a function of temperature. The glass transition temperature (Tg) is a key indicator of when a polymer’s mechanical properties begin to decline:
- PA-MXD6-GF50 (PARA): E' drops sharply at around 85°C, marking its Tg.
- PPA(4T)-GF50: E' remains stable until approximately 125°C, indicating a higher Tg.
Beyond the glass transition, the differences become even more pronounced. Between 150°C and 200°C, PARA exhibits a slight plateau in modulus before dropping to zero at 250°C. In contrast, PPA(4T)-GF50 maintains a high modulus, retaining around 5 GPa even at 250°C. This demonstrates PPA’s superior ability to withstand elevated temperatures without significant loss of stiffness.
-GF50%20-%20Modulus.png) |
| Figure 1: Comparison Dynamic Shear Moldulus E' of PARA-GF50 and PPA(4T). |
Thermal Endurance: UL 746B RTI (Strength) Comparison
To further validate these findings, we examined the Relative Thermal Index (RTI, strength at 1.5 mm thickness) according to UL 746B:
- PA-MXD6-GF50: RTI (strength) = 105°C
- PPA(4T)-GF50: RTI (strength) = 130°C
The higher RTI value for PPA(4T)-GF50 confirms its suitability for applications requiring long-term mechanical integrity at elevated temperatures.
Ways to increase the thermal performance of PARA / MXD6
Increasing the thermal resistance of PARA/MXD6 can be done by blending PARA with PPE (Polyphenylenether) and make a MXD6/PPE alloy which not only exhibits high temperature resistance, high strength, but also good and wear resistance.
Conclusion: Material Selection for High-Temperature Applications
DMA provides valuable insight into how materials behave under dynamic loading across a temperature range. For applications operating above 120°C, PPA(4T)-GF50 clearly outperforms PA-MXD6-GF50, maintaining higher modulus and demonstrating better thermal endurance. Alongside DMA, considering the RTI value is essential for making informed material choices in high-temperature environments.
In summary:
- PPA(4T)-GF50 offers superior high-temperature performance and stability.
- PA-MXD6-GF50 is suitable for applications up to its Tg and shows property loss at higher temperatures above 200°C.
Selecting the optimal material ensures reliability and safety in demanding thermal conditions.
Nevertheless, PARA is outperforming PA and PPA in terms of stiffness, combined with excellent surface aesthetics and lowest water uptake allowing for high dimensional stable parts.
More on PA-MXD6 / PARA here:
Design Properties for Engineers: The ABCs of Polyarylamide (PARA; MXD6)
Design Properties for Engineers: The ABCs of Polyarylamide (PARA; MXD6)
Design Properties for Engineers: Superior Gas Barrier Properties of PolyArylAmide (PARA; MXD6)
Check out my Micro Training below too:
And my dedicated Polyarylamide Hub here.
Thanks for reading & #findoutaboutplastics
Greetings,
Literature:
[1] https://www.syensqo.com/en/brands/ixef-para
[2] https://plasticsfinder.envalior.com/en/datasheet/ForTii%C2%AE+Ace+MX53/O4A8W
[3] https://www.nexeoplastics.com/types/plastics-database-datasheet?id=2131&product=Ixef%C2%AE&grade=1022
[4] https://www.orinkoplastic.com/PA-6I-6T-And-MXD6-pl60644367.html
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