Evolved Gas Analysis of CFRP by Simultaneous TG-DTA and Py-GC/MS

Importance of the Topic

Evolved gas analysis of carbon fiber reinforced plastics (CFRP) broadens understanding of thermal stability and decomposition mechanisms in advanced composite materials. Polyimide‐based CFRP offers significantly higher heat resistance compared with conventional epoxy systems, making it critical for aerospace, automotive and high‐temperature industrial applications.

Objectives and Study Overview

This study aims to characterize the thermal behavior and decomposition products of a thermosetting polyimide prepreg composite using simultaneous thermogravimetric and differential thermal analysis (TG-DTA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Detailed profiling of mass loss events and evolved volatiles over a wide temperature range provides insights into resin stability and residual solvent content.

Methodology and Used Instrumentation

The analysis combined two complementary techniques:

• TG-DTA (Shimadzu DTG-60): Samples were heated at 20 °C/min up to 800 °C under nitrogen flow. Mass change and differential thermal signals were recorded to identify glass transition, desorption, and decomposition steps.
• Py-GC/MS (QP2010Ultra with PY-3030D EGA unit): Samples were held at 100 °C for 5 minutes, then ramped to 800 °C under helium. Volatile species released during heating were separated on a UA-DTM capillary column and identified by mass spectral library matching.

Main Results and Discussion

The TG-DTA profile revealed:

• A glass transition at approximately 250 °C in the DTA curve.
• A minor mass loss (~0.6%) near 270 °C attributed to residual N-methyl-2-pyrrolidone (NMP) solvent.
• A major decomposition onset above 550 °C with mass loss exceeding 10%.

Py-GC/MS evolved gas analysis correlated these events with specific volatiles:

• At ~270 °C: Identification of NMP confirmed incomplete solvent removal, which can impact composite mechanical properties and glass transition temperature.
• Above 600 °C: Detection of aromatic degradation products such as aniline, phenol, CO and CO2 indicated polyimide backbone breakdown.

The close alignment between temperature-dependent mass loss peaks and the EGA thermogram illustrates the ability to link quantitative TG data with qualitative Py-GC/MS identification of decomposition products.

Benefits and Practical Applications

The combined TG-DTA and Py-GC/MS approach enables laboratories and manufacturers to:

• Verify solvent removal efficiency in high-performance prepregs.
• Assess thermal stability limits of polyimide composites for design and quality control.
• Identify critical decomposition pathways to guide resin formulation and processing parameters.

Future Trends and Application Possibilities

Advancements may include:

• Integration of real-time EGA with higher resolution mass spectrometry for trace component quantitation.
• In-situ monitoring of composite cure and post-cure reactions under operational atmospheres.
• Application to hybrid composites and novel high-temperature polymers for aerospace and energy sectors.

Conclusion

The study demonstrates that simultaneous TG-DTA coupled with Py-GC/MS EGA provides a powerful platform for comprehensive thermal and evolved gas characterization of polyimide CFRP prepregs. This work supports improved material design, processing control and reliability assessment for high‐temperature composite applications.