State of the Art Modelle der Reaktionskinetik auf dem Prüfstand: Experimentelle Validierung der Approximation der Vernetzungskurve auf Basis Dynamisch-Mechanischer Analysemethoden an Kautschukbauteilen

Translated title of the contribution: Experimental validation of rubber curing kinetic models based on final product properties

Michaela Hornbachner

    Research output: ThesisMaster's Thesis

    Abstract

    Elastomers have been gaining in importance in technical applications for some time. It is therefore increasingly necessary to accurately describe the crosslinking from the rubber material to the finished elastomer in simulations. Additionally, the mechanical properties of the elastomer need to be predicted properly. The speed of the crosslinking reaction of rubber materials changes significantly as a function of the temperature at which it is performed. With the help of a Rubber Process Analyzer (RPA) these crosslinking reactions can be plotted as a change in transmitted torque over time by applying shear at a given temperature. Subsequently, by normalizing these curves, the degree of cure at the set temperature at any given time can be calculated. However, normalizing the transmitted torque has the disadvantage of accepting a loss of information regarding the mechanical characteristics of the analyzed rubber compound. Nevertheless, this method is state of the art and is applied in simulation programs. The degree of crosslinking exerts a direct influence on the mechanical properties of a produced component. Until now, it was assumed that the mechanical properties depended on the degree of cure, but not on temperature the curing is done. In the course of this master thesis, this widespread assumption was investigated scientifically, with the aim of investigating the loss of information.\\ In order to find the dependence of the process temperature and the influence of the information loss on the mechanical properties, two different rubber compounds were selected. These were then measured with the RPA at selected temperatures of 140~°C - 170~°C with regard to their crosslinking behavior. In addition, positions of the cure curve were defined. Afterwards components were manufactured with this specific degree of crosslinking. Subsequently, the mechanical properties of these components were analyzed via compression set (CS) measurements and dynamic mechanical analysis (DMA). With theoretically identical crosslinking progress, significant differences in the mechanical properties as a function of the crosslinking temperature were measurable. These findings provide scientific evidence of the significant loss of information from normalization and contribute to an improved understanding of rubber behavior. The data obtained provide the basis for a new mathematical model, which will be further developed in cooperation with SIGMA Engineering GmbH and MAGMA Gießereitechnologie GmbH.
    Translated title of the contributionExperimental validation of rubber curing kinetic models based on final product properties
    Original languageGerman
    QualificationDipl.-Ing.
    Awarding Institution
    • Montanuniversität
    Supervisors/Advisors
    • Friesenbichler, Walter, Supervisor (internal)
    Award date1 Jul 2022
    Publication statusPublished - 2022

    Bibliographical note

    embargoed until 01-06-2024

    Keywords

    • elastomer
    • curing kinetics
    • degree of crosslinking
    • degree of cure
    • curing kinetic models
    • EPDM
    • Ethylene-Propylene-Diene-Rubber
    • SBR
    • Styrene-Butadiene-Rubber

    Cite this