(259b) Coupling Rheometry and Computed Tomography to Study the Evolution of Voids during the Consolidation of CF/Pekk Composites

Recently, carbon fiber reinforced thermoplastic (CFRTP) composites have gained in interest over thermoset-based ones, particularly in the aerospace field, because of faster processing and the potentiality to weld and recycle parts [1]. However, the manufacturing of these composites remain challenging as it requires several steps at high temperatures (above 350°C for PEKK (Poly-(ether ketone ketone)-based composites). The last processing step, consolidation, aims at heating and compressing highly-filled plies after lay-up. The goal is to reach a low void content composite (under 1% for the aerospace industry [2]) in order to obtain the desired mechanical properties. To become an economically viable alternative, out-of-autoclave (OOA) consolidation such as Vacuum Bag Only (VBO) needs to be achieved [3].

To optimize the process, one needs to understand how the porosities evolve and are reduced during consolidation. To go beyond classical C-Scan measurements, we propose here a new methodology, which consists in conducting interrupted squeeze flow experiments on CF/PEKK tapes. In parallel, the samples are observed through optical microscopy as well as X-ray high resolution computed tomography in order to analyze quantitatively the porosities and their evolution during consolidation.

References

[1] McCool R, Murphy A, Wilson R, Jiang Z, Price M, Butterfield J, et al. Thermoforming carbon fibre-reinforced thermoplastic composites. Proc Inst Mech Eng Part L J Mater Des Appl 2012;226:91–102. https://doi.org/10.1177/1464420712437318.

[2] Van Hoa S, Duc Hoang M, Simpson J. Manufacturing procedure to make flat thermoplastic composite laminates by automated fibre placement and their mechanical properties. J Thermoplast Compos Mater 2017;30:1693–712. https://doi.org/10.1177/0892705716662516.

[3] Centea T, Grunenfelder LK, Nutt SR. A review of out-of-autoclave prepregs – Material properties , process phenomena , and manufacturing considerations. Compos PART A 2014;70:132–54. https://doi.org/10.1016/j.compositesa.2014.09.029.

Acknowledgments: Synchrotron SOLEIL is acknowledged to providing access to high resolution microtomography (Anatomix Beamline) through proposal n°20210363, and Timm Weitkamp and Mario Scheel for their help in the data acquisition and analysis.