Correlation between post fire behavior and microstructure degradation of aeronautical polymer composites

• Prior fire exposure is more detrimental to the tensile mechanical properties of C/Epoxy than to the ones of C/PPS laminates.
• A correlation has been established between the residual properties and the thermal decomposition of polymer-based composites.
• Char yield is similar in studied materials.
• Melted PPS matrix within the carbon fibers network maintains a partial bonding contrary to C/Epoxy laminates.

The influence of fire conditions on the thermo-physical properties of carbon fibers woven-ply PPS and epoxy has been investigated. More specifically, this work was aimed at comparing the changes on laminates meso- and microstructure due to increasing heat fluxes, and depending on matrix nature. The residual tensile mechanical properties were compared considering the specific thermal decomposition of thermosetting- and thermoplastic-based composites, with a particular attention paid to the char formation along with the mass loss. For the range of heat fluxes studied (up to 50 kW/m2), the post-fire tensile mechanical properties of PPS-based laminates are significantly higher than those of C/Epoxy laminates (about twice higher at 50 kW/m2), not due to the char yield which is similar in the studied materials (about 80%), but rather to a better residual cohesion of the fibrous reinforcement at both microscale (within fiber bundles) and mesoscale (intra and inter-ply).

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