Process analysis of pseudo-plastic deformation behavior of unidirectional reinforced staple fiber organic sheets
Final Report Abstract
By producing staple fibre yarns (SF yarns) from recycled carbon fibres (rCF), these can be further processed into semi-finished textile products with a high fibre length and optimized orientation. These staple fibers offer the advantage that the fibers can move or slide against each other in a molten, highly viscous matrix as a result of an applied tensile stress and thus overcome a major disadvantage of continuous fiber-reinforced thermoplastics, namely their lack of plastic deformability. Semi-finished products based on staple fibers therefore exhibit a pseudo-plastic deformation behavior in the molten state, which can be used for the production of geometrically complex components in the thermoforming process. The main objective of the research project was the further processing of staple fiber yarns made of rCF and PA6 fibers into semi-finished tape products in a modified impregnation and calendering process. The influence of temperature, process speed and stretching on the width and thickness as well as fiber orientation and impregnation was systematically investigated. The mechanical properties of the staple fiber organosheets almost reached the level of virgin material, with the tensile and flexural modulus each being 87 % and the flexural strength 99 % of the values of virgin material. However, the incompatibility of the fiber sizing with the PA6 matrix used led to a significant reduction in tensile strength, so that only 29% of the tensile strength of virgin material was achieved. A new type of test setup for investigating the pseudo-plastic deformation behavior enabled local, homogeneous heating of the tensile specimens in the loaded area. After reaching the target temperature, a highspeed tensile test was carried out, followed by reconsolidation of the samples. To analyze the pseudo-plastic behavior, the test speed, the test temperature and the total stretching of the SF tapes were systematically varied. It was found that an increase in the hot plate temperature leads to a reduction in the maximum tension required for the fibers to slip, while an increased test speed causes an increase in the required tension. In addition, it was observed that an increased hot plate temperature favors a more homogeneous pseudo-plastic deformation. Based on these findings, an existing model was calibrated to describe the tensile tests and used to characterize the material behaviour in the thermoforming process. By combining a high mold temperature, an increased sample temperature and an insulating silicone top layer, a homogeneous pseudo-plastic stretching with a coefficient of variation of 5.13 % was achieved.
Publications
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Data for: New approach for processing recycled carbon staple fiber yarns to unidirectional reinforced recycled carbon staple fiber tape
M. Detzel, P. Mitschang & U. Breuer
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New Approach for Processing Recycled Carbon Staple Fiber Yarns into Unidirectionally Reinforced Recycled Carbon Staple Fiber Tape. Polymers, 15(23), 4575.
Detzel, Martin; Mitschang, Peter & Breuer, Ulf
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„rCF staple fiber tapes”, International IVW Colloquium, 14. – 15.09.2023, Kaiserslautern
M. Detzel, P. Mitschang & U. Breuer
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Influence of the process temperature in the calendaring process on the mechanical properties of rCF staple fiber tapes, SE24, SAMPE Europe Conference 2024 of Society for the Advancement of Material and Process Engineering Europe, 24 .- 26.09.2024, Belfast, Northern Ireland
M. Detzel, C. Scheffler, P. Mitschang, U. Breuer & T. Neumeyer
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“Influence of the processing temperature in the calendaring process of staple fiber yarns on the degree of consolidation and the thermal properties”, PPS-39, 39th International Conference of the Polymer Processing Society, 19. – 23.05.2024, Cartagena de Indias, Colombia
M. Detzel, P. Mitschang & U. Breuer
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„Herstellung von rCF-Stapelfasertapes aus rCF/PA6- Stapelfasergarnen“, AVK Arbeitskreis „Thermoplastic Composites, Tubes & Profiles“, 21.03.2024, Frankfurt/Main
M. Detzel, P. Mitschang & U. Breuer
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“Kohlenstofffasern haben mehr als ein Leben!”, 6. Fachtagung COMPOSITE RECYCLING & LCA, 19. Februar 2025, Stuttgart
M. Detzel, F. Gortner & T. Neumeyer
