Understanding the Ageing of Thermoplastic Composites for Aerospace Applications

Publication associated with this work: Annelise Jean-Fulcrand, Ewen Léger, Frédéric Dau, Martine Dubé, Ilyass Tabiai, Degradation mechanisms of CF/PPS, CF/PEI, and CF/PEEK under combined UV radiation and condensation, Composites Part A: Applied Science and Manufacturing, Volume 198, 2025, 109131, ISSN 1359-835X, https://doi.org/10.1016/j.compositesa.2025.109131. This work was possible thanks to the support of Flying Whales.

The Challenge of Durability: Thermoplastic Composites in Extreme Environments

Thermoplastic composites are increasingly vital in the aviation and aerospace sectors due to their excellent strength-to-weight ratio and design flexibility. However, their long-term performance in harsh operational environments, characterized by exposure to UV radiation and moisture, remains a critical area of investigation. Understanding the degradation mechanisms of these materials is paramount to ensuring the safety and longevity of aerospace components.

Our latest research delves into the ageing behavior of three prominent carbon fibre-reinforced thermoplastic composites: CF/PPS, CF/PEI, and CF/PEEK. We subjected these materials to accelerated ageing tests under combined UV radiation and condensation in a controlled environmental chamber. By meticulously characterizing their degradation through various advanced techniques, we aim to provide crucial insights into how these materials withstand the rigors of real-world aerospace applications.

Key Findings:

• Accelerated Ageing Methodology: We successfully implemented an accelerated ageing protocol in an environmental chamber, allowing for controlled exposure to UV and humidity, mimicking extreme aerospace conditions.
• Diverse Degradation Mechanisms: Our comprehensive characterization, utilizing techniques such as tensile testing, Scanning Electron Microscopy (SEM), confocal microscopy, Energy Dispersive Spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC), revealed distinct degradation mechanisms for each composite type.
• CF/PPS Behavior: We observed that CF/PPS tends to increase cross-linking and brittleness under combined UV and condensation exposure.
• CF/PEI and CF/PEEK Behavior: In contrast, CF/PEI and CF/PEEK primarily exhibited chain-scission degradation mechanisms.
• Implications for Design: These varied degradation pathways highlight the importance of material-specific considerations when designing components for long-term performance in challenging environments.

What Does This Mean for the Future of Aerospace Materials?

This research offers vital insights for enhancing the reliability and lifespan of thermoplastic composites in aerospace:

• Improved Material Selection: Our findings provide a scientific basis for selecting the most suitable thermoplastic composite for specific aerospace applications, considering anticipated environmental exposures.
• Enhanced Component Design: Understanding the degradation mechanisms allows engineers to design components that are more resilient to environmental stressors, potentially extending their service life.
• Predictive Maintenance: The insights gained can contribute to developing more accurate predictive models for material degradation, enabling proactive maintenance and reducing unforeseen failures.

By thoroughly investigating the ageing behavior of these advanced materials, we are paving the way for more robust and reliable aerospace structures, ultimately contributing to safer and more efficient air and space travel.