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Title: An evaluation and development of bonding technologies for rapid disassembly of automotive vehicles
Author: Lu, Yuchen
ISNI:       0000 0004 8503 687X
Awarding Body: Oxford Brookes University
Current Institution: Oxford Brookes University
Date of Award: 2015
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The end-of-life vehicle (ELV) situation, international legislation and recycling issues for future multi-material vehicles all necessitate the development of new joining solutions which enable rapid disassembly for automotive vehicle maintenance or recycling scenarios. In this thesis, the innovations in adhesive disbonding technologies were comprehensively reviewed and divided into three categories of potential methods for disassembly of adhesive joints: general/conventional methods, tailored adhesive formulations, functional additives. It was found that the incorporation of functional additives into commercially available adhesive system generally received more attention and showed higher potential for automotive applications. Thermally expandable microspheres (TEMs) were identified as the most promising approach and therefore selected for experimental study in this thesis. Four TEMs grades with different initiation temperature, surface chemistry and particle size distribution were provided by three TEMs manufacturers. A two component epoxy based structural adhesive 3M Scotch-Weld 9323 and EN AW-6082 T6 aluminium substrate were used in the experimental testing. The experimental test programme was established to investigate the disbonding performance and general properties of TEMs system. The results contributed to a better understanding of the TEMs concentration effect, TEMs' surface chemistry effect, environmental conditioning effect, disbonding mechanism, and TEMs/adhesive compatibility issue. Poor TEMs/adhesive adhesion, which led to interfacial disbonding under stress, was identified as the main reason for reduced in-service performance. To address the issue of TEMs/adhesive compatibility, atom transfer radical polymerization (ATRP) with activators regenerated by electron transfer (ARGET) or ARGET ATRP technique was reviewed and employed to modify the TEMs surface. TEMs were grafted with poly(glycidyl methacrylate) (PGMA) chains which contain reactive epoxy groups to form strong covalent bonds with epoxy based adhesive system. TEMs were successfully modified at three temperatures (23 ⁰C, 30 ⁰C, and 37⁰C) after 3 hours and 5 hours respectively. A clear trend of the temperature effect on TEMs surface modification was observed. The mechanical properties and resistance to environmental conditioning of the TEMs/adhesives system were substantially improved. TEMs modified at 37⁰C for 3 hours achieved the highest improvement whilst retaining the same disbonding characteristics.
Supervisor: Broughton, James ; Winfield, Pat Sponsor: Oxford Brookes University
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral