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Session: Session 3: Thermoplastic Tapes
Session starts: Tuesday 14 April, 14:00
Presentation starts: 14:20
Room: Main

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Ashley Chadwick (DLR)
Yannick Schäfer (DLR)
Clara Thaldorf (DLR)
Stefan Fliescher (TEXTECHNO)

Abstract:
The desire for high-speed additive manufacturing, both Automated Fibre Placement (AFP) and 3D printing, has launched CF-LMPAEK from its release approximately five years ago to become one of the most widely-utilised materials in the development of new thermoplastic composites parts for the aviation industry. While the base polymer is currently procured from a single supplier, its conversion to a composite prepreg by any one of several manufacturing companies yields drastically different products. Commercial entities and research institutes alike must therefore ask poignant questions regarding the quality and applicability of these prepregs: How well do supplier datasheets represent their products? Are commercial tapes equivalent? Can they be substituted for one another if the need arises? In this work, six CF-LMPAEK prepregs from four well-known suppliers are measured using different techniques and compared to one another as well as their own manufacturer-supplied datasheets. Optical microscopy is used to assess the fibre distribution, porosity, and overall homogeneity of the composite material. Measurements of prepreg width, thickness, and other properties are also performed using the TAPESCAN facility from TEXTECHNO. This facility measures properties continuously over the full length of the material spool, providing parameter resolution of 0.1m and therefore thousands of datapoints over the spool length. The prepreg spools measured in this study yielded between 1400 and 4900 datapoints. The results of this investigation highlight that prepregs can deviate significantly from their target values and indeed each other. Nominal 59% fibre volume prepregs were recorded to exhibit vastly different median values and distributions, with some falling as low as 50%. The prepreg width was also seen to vary between products, with 12.7mm (1/2”) unidirectional tapes displaying concentrations between 12.6mm and 13.0mm. While such systematic offsets can be accounted for, it is essential to obtain accurate information on the product on hand.