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Authors
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Kahlmeyer, M. ; Winkel, A. ; Scheel, J. ; Melnyk, I. ; Müller, A. ; Fery, A. ; Ricoeur, A. ; Böhm, S.
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Title
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Microencapsulated markers for damage detection in adhesive joints
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Date
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21.02.2018
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Number
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54290
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Abstract
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The durability of adhesive bonds is not only affected by the quality of the bonding procedure but also by aging processes which influence the bond performance negatively on a long time scale. Especially the building industry, where safety related joints are increasingly boned with adhesives, demands new quality assurance methods. Therefore, appropriate monitoring techniques for developing cracks or critical stresses are essential.<br />A new approach for in situ monitoring of transparent/opaque adhesives will be presented in this paper. Microcapsules, filled with special dyes, are embedded into adhesive systems. Upon breakage through cracks or exceedance of certain stress levels within the adhesive seam, the capsules release their liquid cores which leads to a detectable color change and, thus, enables non-destructive condition monitoring of the bond. In order to examine the feasibility of the approach, microcapsules are formed via interfacial polymerization. Microscopy techniques such as optical or scanning electron microscopy allow to study the capsule morphology, shape and dimensions (size and wall thickness) in dependence to the preparation procedure. Thereupon, the durability and release behavior are investigated with thermal analyses (differential scanning calorimetry and thermogravimetric analyses). Atomic force-based nanoindentation measurements give an insight into the size-dependency of mechanical properties like stiffness and burst forces.<br />Finally, the principle of health monitoring is evaluated by dispersing the prepared capsules in the adhesive systems.<br />Apart from the experimental examinations, numerical simulations of the crack propagation within the adhesive matrix are performed to demonstrate the effect of different microcapsule sizes and capsule walls on the fracture behavior.<br />This preliminary study demonstrates the basic feasibility of the approach, but there is still a great need for investigations in order to employ the concept for industrial purposes.
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Publisher
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Journal of Adhesion
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Wikidata
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Citation
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Journal of Adhesion 94 (2018) 767-783
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DOI
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https://doi.org/10.1080/00218464.2018.1433037
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Tags
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microencapsulation non-destructive testing nanofillers epoxies
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