Advanced Silicone Materials for Harsh Aerospace Environments

June 1, 2026

Aerospace and defense systems demand materials capable of maintaining performance under extreme environmental and operational stressors, including wide thermal cycling ranges, exposure to hydrocarbon fuels, vacuum conditions, and repeated mechanical strain. Silicone-based materials have become essential in these environments because they can retain elasticity, stability, and functionality where many traditional materials fail.

Silicones are widely used as coatings, adhesives, sealants, and elastomers in aircraft and spacecraft applications. Their chemical structure enables resistance to both high and low temperatures, while also providing durability against solvents and fuels such as jet fuel. In contrast, many conventional elastomers degrade under prolonged thermal exposure or become brittle at cryogenic temperatures.

For space applications, vacuum-induced outgassing presents an additional challenge. Volatile components may evaporate under low-pressure, high-temperature conditions, and condense on sensitive surfaces such as optics or solar arrays. To address this, advanced silicones are engineered for high purity and low-outgassing behavior.

This article summarizes key findings on the thermal, mechanical, and reliability performance of advanced silicone materials, with a focus on fluorosilicones and diphenyl-dimethyl siloxanes. For detailed methodologies and expanded datasets, please refer to the full article located on NuSil’s website.

Material Design and Evaluation Approach

Silicones used in aerospace applications are engineered through targeted molecular modifications that enhance specific performance attributes. Incorporating diphenyl groups to create diphenyl-dimethyl copolymers improves thermal stability, while the addition of trifluoropropyl-bearing siloxanes greatly enhances resistance to hydrocarbon fuels. These tailored chemistries enable silicones to meet highly specialized operational requirements.

Performance evaluation spans thermal stability, mechanical behavior at low temperatures, resistance to chemical exposure, and outgassing under vacuum. The following sections summarize the most relevant performance outcomes and their implications.

Thermal Performance

Figure 1. TGA results of four fluorosilicone materials in an air environment from 25 °C to 600 °C (250 °C to 420 °C plotted).

Fluorosilicones demonstrate strong resistance to thermal degradation under both dynamic and sustained heating conditions. Thermogravimetric analysis shows that all tested materials experience less than 3% mass loss at temperatures up to 325 °C in air environments, with high-performance formulations maintaining this stability even up to 400 °C (Figure 1).

Isothermal testing at 275 °C for one hour confirms these findings, with comparable mass loss observed across materials. Together, these results indicate that fluorosilicones can maintain structural integrity during both transient and prolonged high-temperature exposure.

Figure 2. DSC of standard HCR and broad operating temperature HCR.

In low temperature environments, maintaining material flexibility becomes a significant engineering and design challenge, one that silicones have reliably addressed in aerospace and aviation applications for decades. Differential scanning calorimetry reveals a key distinction between standard and modified silicone formulations. Conventional high-consistency rubber exhibits a crystallization transition near -50 °C, which can lead to embrittlement. In contrast, broad operating temperature HCR materials do not show this transition, maintaining flexibility down to approximately -120 °C (Figure 2).

Dynamic mechanical analysis also demonstrates this material performance aspect. Standard polydimethylsiloxane-based silicone elastomers tend to show a sharp increase in modulus near the crystallization point, indicating stiffening in a typical range of -40 °C to – 50 °C depending on thermal testing or application conditions.

Figure 3. DMA of standard and broad operating temperature HCRs.

In contrast, the diphenyl-dimethyl-based silicone elastomer maintains a smooth modulus shift without sudden crystallization events throughout the full temperature range tested (Figure 3).

Mechanical Durability

Figure 4. Mimicking a low-temperature fatigue test at –90 °C for both standard and custom HCRs (filled symbols: elastic response hollow symbols: viscous response).

Mechanical performance under cyclic stress is critical for long-term reliability, particularly in environments, where materials experience repeated deformation at low temperatures. Fatigue testing at -90 °C highlights the differences between standard and modified silicone systems (Figure 4).

Standard HCR materials exhibit a gradual increase in stiffness over repeated strain cycles, signaling progressive embrittlement and reduced resilience. In contrast, broad operating temperature HCR materials maintain consistent mechanical properties even after extensive cycling, demonstrating their ability to withstand combined thermal and mechanical stress without degradation.

Resistance to Hydrocarbon Fuel Exposure

Exposure to hydrocarbon fuels such as JP-8 is common in aerospace and defense applications, making chemical resistance a key performance requirement. Swell testing conducted over seven days at elevated temperature shows a dramatic difference between fluorosilicones and conventional silicones.

Figure 5. Mass swell results for fluorosilicones and non-fluorinated silicones when soaked in heated jet fuel for seven days.

The 100 percent molar trifluoropropyl-bearing silicone elastomers exhibited low mass swell, averaging under 6 percent mass change, while non-fluorinated silicones showed mass increases exceeding 130 percent (Figure 4). This contrast highlights the effectiveness of fluorinated chemistries in limiting fuel absorption and maintaining material integrity (Figure 5).

Even under conditions more severe than typical operational exposure and military specification testing conditions, fluorosilicones remain well within acceptable limits, reinforcing their suitability for applications involving direct fuel contact.

Outgassing Behavior in Vacuum Environments

In space environments, outgassing can compromise the performance of sensitive systems and affect bonding operations. Testing using ASTM E595 and ASTM E1559 provides both total mass loss values and time-dependent outgassing profiles to ensure the highest quality and performance materials are selected for such critical applications.

Results show that all evaluated materials meet stringent aerospace requirements for low outgassing. Ultra-low outgassing silicones (dashed lines, Figure 5) particularly demonstrate significantly reduced levels of condensable volatiles compared to standard low-outgassing materials.

Figure 6. Comparison of the TML percent (80 K QCM) over time for NuSil products tested by ASTM E 1559. Dashed lines are ultra-low outgassing materials, and solid lines are low outgassing materials.

Time-dependent analysis reveals that outgassing occurs most rapidly during the initial hours of exposure, followed by a rapid decline and stabilization. Some materials reach steadystate behavior within the first several hours, indicating minimal long-term contamination risk ( Figure 6). These findings highlight the importance of material purification and formulation control in reducing volatile content and ensuring compatibility with vacuum-sensitive applications.

Integrated Performance Perspective

Taken together, these results illustrate the ability of advanced silicone materials to address multiple, simultaneous challenges in aerospace environments. Their performance spans extreme temperatures, mechanical stress, chemical exposure, and vacuum conditions without significant degradation.

Fluorosilicones provide critical advantages in fuel resistance, while use of diphenyl-dimethyl systems extends operational limits at both cryogenic temperatures and extreme heat. At the same time, low-outgassing formulations ensure compatibility with sensitive optical and electronic systems in space applications.

These capabilities are not inherent to all silicones but are achieved through deliberate material design, controlled synthesis, and rigorous testing. As a result, silicones remain a highly adaptable platform for meeting evolving aerospace requirements.

Conclusion

As aerospace and defense systems become more advanced, the demands placed on materials continue to increase. Components must perform reliably under extreme and often overlapping conditions, including thermal cycling, mechanical stress, chemical exposure, and vacuum environments.

The results presented here demonstrate that advanced silicone materials, particularly fluorosilicones and broad operating temperature phenyl-based copolymers, are well-suited to meet these challenges. They offer strong thermal stability across a wide temperature range, resistance to embrittlement and fatigue, excellent performance in hydrocarbon-rich environments, and low outgassing characteristics.

These attributes make silicones a critical material class for next-generation aerospace applications. Their continued development and optimization will play an important role in enabling reliable, high-performance systems in increasingly demanding operational environments.

This article was written by Daniel E. Hess, Technical Marketing Engineer, NuSil Technology (Carpinteria, CA). For more information, visit here .