Abstract
“The transportation sector, aerospace and automotive in particular, is striving to reduce vehicle weight to improve fuel economy. The high specific mechanical properties of fibre-reinforced composites make them an attractive option for reaching this goal. Among this class of materials, thermoplastic composites are becoming increasingly popular. Recent years have shown an increase in applications and a rising demand for these thermoplastic composites. This comes with the drawback of larger volumes of industrial scrap. The combination of the high value of the scrap material and legislative incentives is pushing the industry to develop recycling solutions for this material.
This thesis proposes a new recycling route for continuous-fibre thermoplastic composites to handle the generated production scrap, which consists of the following processing steps: shredding, sieving, mixing and compression moulding. The main objective is to develop the technical feasibility and economic viability of this recycling solution. This thesis focuses on the role of processing, which is evaluated by identifying and characterising the relevant material properties and their relation to the processing steps mentioned for this recycling solution.
Four aspects have been investigated in this thesis: i. analysis of fibre length and flake size after
shredding and sieving, ii. characterisation of the quality of mixing in doughs, iii. identification of the deformation mechanisms during the squeeze flow of these doughs, and iv. characterisation of the microstructural heterogeneities in moulded components. Novel characterisation and analysing techniques were implemented to identify and measure key material properties for the shredding, sieving, mixing and compression moulding steps, as well as in compression moulded panels.
Said techniques were employed to understand the causes and extend of inherent variations in material properties in these recycled composites, and latter to reduce these variations. Considering the overall results and main objective of the thesis, it was found that the mixing step is key in this recycling solution and that improvement of the quality of mixing is required.”
This thesis proposes a new recycling route for continuous-fibre thermoplastic composites to handle the generated production scrap, which consists of the following processing steps: shredding, sieving, mixing and compression moulding. The main objective is to develop the technical feasibility and economic viability of this recycling solution. This thesis focuses on the role of processing, which is evaluated by identifying and characterising the relevant material properties and their relation to the processing steps mentioned for this recycling solution.
Four aspects have been investigated in this thesis: i. analysis of fibre length and flake size after
shredding and sieving, ii. characterisation of the quality of mixing in doughs, iii. identification of the deformation mechanisms during the squeeze flow of these doughs, and iv. characterisation of the microstructural heterogeneities in moulded components. Novel characterisation and analysing techniques were implemented to identify and measure key material properties for the shredding, sieving, mixing and compression moulding steps, as well as in compression moulded panels.
Said techniques were employed to understand the causes and extend of inherent variations in material properties in these recycled composites, and latter to reduce these variations. Considering the overall results and main objective of the thesis, it was found that the mixing step is key in this recycling solution and that improvement of the quality of mixing is required.”
| Original language | English |
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| Qualification | Doctor of Philosophy |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 3 Oct 2019 |
| Place of Publication | Enschede |
| Publisher | |
| Print ISBNs | 978-90-365-4852-6 |
| DOIs | |
| Publication status | Published - 3 Oct 2019 |