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Experimentally calibrated modeling technique for the cross linking mechanism of epoxy resin and its influence on mechanical properties

  • Epoxy resins are one of the first choices for structural adhesives and are widely used in combination with fibers as fiber reinforced plastics (FRP). The mechanical properties are the result of the complex chemical network structure that is generated by the thermally catalyzed cross linking reaction. Numerical simulations on the atomistic length scale are appropriate tools to understand and improve the mechanical properties and its mechanisms of epoxy resins. This leads to the necessity of a model generation procedure that covers the characteristic cross linking mechanisms of epoxy resins and is able to generate a realistic representation of the network structure. Research in the field of Molecular Dynamic based curing kinematics of polymers has led to cross linking procedures that are based on the main chemical curing reaction and can produce models, whose mechanical properties are in agreement with experimental values. Nevertheless an assessment of the realism of these cross linkingEpoxy resins are one of the first choices for structural adhesives and are widely used in combination with fibers as fiber reinforced plastics (FRP). The mechanical properties are the result of the complex chemical network structure that is generated by the thermally catalyzed cross linking reaction. Numerical simulations on the atomistic length scale are appropriate tools to understand and improve the mechanical properties and its mechanisms of epoxy resins. This leads to the necessity of a model generation procedure that covers the characteristic cross linking mechanisms of epoxy resins and is able to generate a realistic representation of the network structure. Research in the field of Molecular Dynamic based curing kinematics of polymers has led to cross linking procedures that are based on the main chemical curing reaction and can produce models, whose mechanical properties are in agreement with experimental values. Nevertheless an assessment of the realism of these cross linking procedures is difficult, since various complex aspects, such as the influence of the activator molecules or catalyzing chemical reactions may be important, but are hard to characterize. By using the method of in situ near-infrared spectroscopy (NIR) the time and temperature evolution of the reactive groups, epoxy and either amine or anhydrite curing groups, can be measured. It has been shown that this method is well suited for analyzing the curing process and to characterize the fully hardened epoxy resin. Thus NIR measurements of the cross linking kinetics of epoxy resins give a valuable insight in the curing process that can be used to calibrate and assess numerical approaches of the cross linking procedure. A modeling technique for the curing kinematics of epoxy resins is presented, that is able to realistically represent the cross linking mechanism and generate simulation models with characteristics in good agreement with experimentally analyzed cured epoxy resins. This is achieved by calibrating the cross linking parameters and is shown by a comparison of both, the cross linking procedure and the resulting network structure, with experimental results of NIR measurements. The modeling approach is incorporated in the Molecular Dynamic Finite Element Method (MDFEM) framework and implements a step by step molecular network build-up. This allows to perform MDFEM equilibrium iterations during the curing procedure in order to create realistic and well equilibrated simulation models. Furthermore MDFEM simulations of tensile tests are presented to evaluate the influence of the network structure on the elastic mechanical properties. These numerical tests also illustrate the need for accurate models when deriving material properties from atomistic length scale simulations.zeige mehrzeige weniger

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Metadaten
Autor*innen:R. Unger
Koautor*innen:B. Daum, Ulrike Braun, R. Rolfes
Dokumenttyp:Vortrag
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2017
DDC-Klassifikation:Religion / Religion
Freie Schlagwörter:Epoxy resin; Mechanics; NIR spectroscopy
Veranstaltung:ICCS 20
Veranstaltungsort:Paris, France
Beginndatum der Veranstaltung:04.09.2017
Enddatum der Veranstaltung:07.09.2017
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:09.10.2017
Referierte Publikation:Nein
Eingeladener Vortrag:Nein
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