FFKM, or perfluoroelastomers, are a group of elastomers that are used across a wide range of industries.
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Material selection for spacecraft and satellite systems extends far beyond traditional sealing considerations. While factors such as chemical resistance, compression set, and operating temperature remain important, contamination control is of critical consideration.
For engineers designing systems for Low Earth Orbit (LEO), Earth observation satellites, propulsion systems, and scientific payloads, material outgassing can significantly influence long-term reliability and performance. To support these applications, TRP Polymer Solutions has recently completed independent ECSS-Q-ST-70-02C thermal vacuum outgassing testing on three specialist elastomer compounds: F207, TRPlast LT45 and E334.
In this blog, we cover the independently verified data results of testing these materials and how they demonstrate the resilience needed for contamination-sensitive extraterrestrial applications.
Under vacuum conditions, polymer materials can release volatile compounds that would otherwise remain trapped within the elastomer matrix. These compounds may migrate throughout the spacecraft before condensing onto colder surfaces such as optical sensors, lenses, solar arrays, thermal control surfaces, and scientific instrumentation.
Even extremely small levels of contamination can affect optical transmission, sensor performance and measurement accuracy. As a result, low-outgassing materials are often specified throughout spacecraft assemblies, particularly where contamination-sensitive payloads are present.
For this reason, polymers for space applications are required to be rigorously tested against recognised industry standards before they can be specified for flight hardware.
ECSS-Q-ST-70-02C is a European Space Agency standard used to assess the outgassing characteristics of materials intended for space applications. The standard evaluates three key parameters:
Total Mass Loss (TML) is the percentage of mass lost during vacuum exposure. Lower values indicate greater material stability.
Collected Volatile Condensable Materials (CVCM) is the percentage of volatile material released from the sample that subsequently condenses onto a collector surface. This is one of the most important measurements when assessing contamination risk.
Recovered Mass Loss (RML) is the remaining mass loss after post-test conditioning. This provides an indication of the non-recoverable material loss.
The standard acceptance criteria – the property acceptance limits – are:
All three of the materials that we have developed to dependably withstand the intensive conditions of space applications – F207, TRPlast® LT45, and E334 – successfully met the ECSS-Q-ST-70-02C acceptance criteria during our testing. The average results of these tests are shown below:
| Material | Polymer Type | TML (%) | CVCM (%) | RML (%) | Result |
| F207 | Ultra Low Temperature FKM | 0.169 | -0.007 | 0.015 | Pass |
| TRPlast® LT45 | Low Temperature FFKM | 0.100 | -0.006 | 0.038 | Pass |
| E334 | EPDM | 0.254 | 0.005 | 0.171 | Pass |
All three materials comfortably achieved the required acceptance limits, clearly demonstrating suitability for use in low-outgassing sealing applications. Of particular note is the exceptionally low CVCM performance exhibited by all three compounds, which indicates their minimal condensable contamination under test conditions.
While all three materials passed the outgassing requirements, each offers different advantages depending on the specific application, as explained below:
F207 is a specialist fluoroelastomer (FKM) developed for applications requiring both broad chemical resistance and excellent low-temperature performance. Its key characteristics include:
Its typical applications include fuel system seals, fluid handling components, and sealing elements exposed to challenging thermal environments.
TRPlast® LT45 is a perfluoroelastomer (FFKM) designed for applications requiring exceptional chemical resistance alongside extended low-temperature capability. Its key characteristics include:
For those seeking a low-outgassing material capable of operating in chemically aggressive environments, LT45 provides a compelling solution.
E334 is a specialist EPDM compound developed by TRP specifically for use in ADN monopropellant systems.
Unlike conventional EPDM rubber grades, EPDM E334 was formulated to provide compatibility with modern green propulsion technologies whilst maintaining good low-temperature performance and strong chemical resistance.
The key characteristics of this elastomer include:
The material has seen repeated use within rubber diaphragm and bladder applications associated with modern spacecraft propulsion systems.
While numerical outgassing data provides the primary acceptance criteria, visual inspection can often provide additional engineering insight that may influence material selection decisions.
During testing, the collector plates associated with E334 displayed visible signs of fogging. Despite this observation, the material remained comfortably within the ECSS-Q-ST-70-02C acceptance limits and achieved a CVCM value of just 0.005%.
This highlights an important consideration when specifying elastomers for space applications. Whilst a material may satisfy the requirements of a recognised standard, the suitability of that material ultimately depends on the specific application, its location within the spacecraft, and the sensitivity of nearby components.
For example, a material that performs exceptionally well within a propulsion system, pressure regulation device, or fluid handling assembly may require additional consideration if located in close proximity to optical payloads, imaging systems, or scientific instrumentation. Understanding these nuances is often just as important as reviewing the test data itself.
This is where early engagement with TRP’s engineering team can add significant value. Our specialists work with customers to interpret material performance data alongside application requirements, helping to identify potential contamination risks, optimise seal selection, and recommend appropriate materials for the operating environment.
Whether specifying standard O-rings, custom rubber seals, diaphragms, or complex elastomer components, we support our customers throughout the design process to significantly reduce risk and improve long-term reliability.
The photographs obtained during our testing provide a useful visual reference and demonstrate why experienced engineering judgement should always complement laboratory test results when designing for critical space applications.
Selecting the correct rubber materials is only one aspect of achieving reliable sealing performance in space systems, and we can support customers throughout the development process. By combining our in-house formulation expertise with UK manufacturing capability, we can support projects from initial rubber moulding design through to production.
If you are specifying materials for satellite, LEO, optical observation, propulsion or contamination-sensitive applications, our technical team can help. With decades of experience in producing custom rubber components specially made for the toughest of applications across a diverse range of industries, we can assist you in producing the perfect sealing solution for your requirements.
Contact TRP Polymer Solutions to discuss how our ECSS-Q-ST-70-02C tested materials and custom sealing solutions can help you today.
4 Aug 2026 • 
6 min read
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