Scaling up a Two-Step Pyrolysis of CFRP: Study of Validation and Robustness
Topic(s) : Material science
Co-authors :
Marina CORVO ALGUACIL (SWEDEN), Kentaro UMEKI (SWEDEN), Roberts JOFFEAbstract :
This work focuses on the validation and robustness studies of a two-step pyrolysis recycling process for Carbon Fiber Reinforced Polymer (CFRP). With the increasing demand for stiffer and lighter materials in the transportation and energy sectors, CFRP has gained significant popularity. However, the cost of carbon fibers (CF) remains high. One way to reduce cost of these materials is to use fibers recovered from composite waste, however, the market for recycled CFRP is still in its early stages with limited use in high-value applications.
To unlock the full potential of the recycled CF (rCF) market, more research is needed to assess how diverse recycling parameters affect rCF properties. Moreover, to become truly sustainable it should be possible to recover CF more than once and therefore investigation of potential of multiple recycling cycles of rCF is of great interest. Extending prior research [1] on model composites recycled up to three times by using two distinct methods, this work aims to validate and prove the robustness of the recycling process in use. Thus, the work is divided into two stages, first validation and then robustness, with the ultimate objective to work towards scaling up recycling from laboratory scale to industrial application.
Since previous study was carried out on model composites, which have rather low fiber volume fraction compared to industrially manufactured advanced composites, the results must be validated on a larger scale. Therefore, validation study is performed on a CF composite laminate. The laminate is manufactured using the same raw materials as the model composites. Then, specimens cut from the plate are recycled. Mechanical properties of fibers are evaluated from tensile test for comparison of results obtained from model composites. However, because of the limitations introduced by the lab-scale setup, long fibers cannot be reprocessed multiple times. Thus, preventing the validation of multiple recycling cycles by the same method.
As composites waste can vary in geometry, to ensure a robust recycling process that can accommodate complex shapes is important. Thus, the second stage of the work focuses on studying the effect of complex geometries on the recovered rCF to assess the robustness of the recycling process. Complex geometries are simulated with model composites featuring virgin carbon fibers bent at an angle close to 180 degrees as shown in Fig. 1 (right). Unlike with the CF laminates used for validation, the reduced dimensions of the model composites allow to carry out multiple recycling cycles. After each recycling rCF are characterized (tensile test) and mechanical properties are compared with data from the prior study.
The results of this study contribute to the understanding of CFRP recycling from realistic end-of-life composites and proves the potential for scaling up a recycling process to meet the demand for environmentally sustainable and economically viable composites.
To unlock the full potential of the recycled CF (rCF) market, more research is needed to assess how diverse recycling parameters affect rCF properties. Moreover, to become truly sustainable it should be possible to recover CF more than once and therefore investigation of potential of multiple recycling cycles of rCF is of great interest. Extending prior research [1] on model composites recycled up to three times by using two distinct methods, this work aims to validate and prove the robustness of the recycling process in use. Thus, the work is divided into two stages, first validation and then robustness, with the ultimate objective to work towards scaling up recycling from laboratory scale to industrial application.
Since previous study was carried out on model composites, which have rather low fiber volume fraction compared to industrially manufactured advanced composites, the results must be validated on a larger scale. Therefore, validation study is performed on a CF composite laminate. The laminate is manufactured using the same raw materials as the model composites. Then, specimens cut from the plate are recycled. Mechanical properties of fibers are evaluated from tensile test for comparison of results obtained from model composites. However, because of the limitations introduced by the lab-scale setup, long fibers cannot be reprocessed multiple times. Thus, preventing the validation of multiple recycling cycles by the same method.
As composites waste can vary in geometry, to ensure a robust recycling process that can accommodate complex shapes is important. Thus, the second stage of the work focuses on studying the effect of complex geometries on the recovered rCF to assess the robustness of the recycling process. Complex geometries are simulated with model composites featuring virgin carbon fibers bent at an angle close to 180 degrees as shown in Fig. 1 (right). Unlike with the CF laminates used for validation, the reduced dimensions of the model composites allow to carry out multiple recycling cycles. After each recycling rCF are characterized (tensile test) and mechanical properties are compared with data from the prior study.
The results of this study contribute to the understanding of CFRP recycling from realistic end-of-life composites and proves the potential for scaling up a recycling process to meet the demand for environmentally sustainable and economically viable composites.