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Item type:Publication, Access status: with files , CFRP-recycling following a pyrolysis route : process optimization and potentialsPyrolysis is a well known method to recover carbon fibers from composite waste. In order to bring these recycled carbon fibers back into new composites, and to provide a `closed loop' for this material, their properties have to be investigated and proved suitable for new products. In a former study a strong influence of the pyrolysis process on the surface of the recovered fibers was found. This in turn influenced other properties like fiber strength, electrical properties and fiber-matrixadhesion. These results offer the possibility to control individual properties of recycled carbon fibers and their composites, but on the other hand they indicate a necessity for process optimization in order to provide a high quality of the recycled fibers. In this study different process parameters during pyrolysis were investigated and optimized in order to provide the reclaimed carbon fibers with properties close to new fibers. The optimization was done by labscale pyrolysis experiments performed in a thermogravimetric analyzer (TGA), with variation of pyrolysis temperature, isothermal dwell time and oven atmosphere, respectively. The recovered fibers were analyzed by scanning electron microscopy and Raman spectroscopy. Finally a pyrolysis test on a semi-industrial-scale was successfully performed to demonstrate the technical viability of the optimized process parameters.Publicationtype: Journal ArticleScopus© Citations 270 410 2841 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , An approach to minimize inhomogeneous stress distribution in compression testing of CFRPTo measure the compression strength of unidirectional Carbon Fibre Reinforced Plastics (CFRP) is difficult. Various compression tests show significant inhomogeneous stress states, leading to a multiple failure mode. In the new approach different lubricants between specimen and loading equipment were tested to reduce multiaxial stress state in the loading area. The test method was modelled by Finite-Element Analysis (FEA) using a multiple body contact model including different coefficients of friction between the bodies as well as plasticity. The unidirectional cylindrical specimens were tested under compression. The model predictions and the tests show good agreement in the deformed shapes under loading. Depending on the lubricant the failure changes from fibre buckling to a pure cross tensile failure. However, the compression strength is not highly dependent on the edge modification, whereas deviation and failure are.Publicationtype: Conference Paper19