ISBN 9783843949941

978-3-8439-4994-1, Reihe Ingenieurwissenschaften

Frank Manis
Thermische Behandlung und mechanische Bewertung von Carbonfasern im Recyclingprozess

263 Seiten, Dissertation Technische Universität München (2021), Softcover, A5

Zusammenfassung / Abstract

This thesis is a treatise on the modification of mechanical properties and the fibre matrix-bonding of thermally treated carbon fibres. Thermal treatment is understood to be a process that is frequently used for the recycling of carbon fibres. The focus is on processes in nitrogen and oxygen atmosphere at temperatures between 400 °C and 800 °C. Different ways of oxygen flow and oxygen concentration are investigated in a lab-scale batch furnace. This furnace has a volume of 166 l and is therefore representing a rather large facility for thermals investigations on carbon fibres. For the material selection different carbon fibre manufacturers, dry waste as well as

CFRP-waste is chosen and thermally treated. The main parameters to be investigated are the single fibre tensile strength and single fibre tensile stiffness but also the change of the fibre surface. Subsequently, a selected amount of treated fibres are examined for their fibre-matrix-adhesion in a new single-fiber pull-out test. In particular, the single-fiber tensile test and the pull-out test are preceded by a detailed characterization of measurement and test parameters.

Furthermore larger CFRP structures are treated and their layers are separated with a introduced thermal process. The aim behind is to investigate the influence of the residual fibre char that stick to the single filament and may influence the fibre-matrix-adhesion. The separated layers were infiltrated again, followed by macroscopic tests the compare the micromechanical and macro mechanical behaviour of carbon fibres in comparison to their CFRP. Here, the focus is on fibre-matrix adhesion, which is why ILSS, edge-shear and shear frame tests were carried out in particular. The mayor influencing factor for good mechanical properties of recycled carbon fibre material are presented and explained at the end.