Peroxide-Based Crosslinking of Solid Silicone Rubber, Part I: Insights into the Influence of Dicumylperoxide Concentration on the Curing Kinetics and Thermodynamics Determined by a Rheological Approach

Maurício Azevedo, Anna Maria Monks, Roman C. Kerschbaumer, Sandra Schlögl, Clemens Holzer

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung


Predicting the curing behaviour of industrially employed elastomeric compounds under typical processing conditions in a reliable and scientifically driven way is important for rubber processing simulation routines, such as injection moulding. Herein, a rubber process analyser was employed to study the crosslinking kinetics of solid silicone rubber based on the concentration of dicumylperoxide. A model was proposed to describe the optimal cure time variation with peroxide concentration and temperature, based on the analysis of processing parameters applying kinetic and thermodynamic judgments. Additionally, the conversion rate was described with the aid of a phenomenological model, and the effect of dicumylperoxide concentration on the final crosslink state was investigated using kinetic and thermodynamic explanations. Optimal curing time was affected both by temperature and dicumylperoxide concentration. However, the effects were less pronounced for high temperatures (>170°C) and high concentrations (>0.70 phr). A limit on the crosslink state was detected, meaning that the dicumylperoxide capacity to crosslink the silicone network is restricted by the curing mechanism. Curing restrictions were presumed to be primarily thermodynamic, based on the proton abstraction mechanism that drives the crosslinking reaction. In addition to providing more realistic crosslinking models for rubber injection moulding simulation routines, the results of this study may also explain the chemical behaviour of organic peroxides widely used for silicone crosslinking.
PublikationsstatusVeröffentlicht - 18 Okt. 2022

Bibliographische Notiz

Funding Information:
The research work of this paper was performed at the Polymer Competence Center Leoben GmbH (PCCL, Austria) within the framework of the COMET-program of the Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology and the Federal Ministry for Digital and Economic Affairs, with contributions from the Montanuniversitaet Leoben (Department of Polymer Engineering and Science, Polymer Processing and Materials Science and Testing of Polymers). The authors kindly acknowledge Bernard Lechner for experimental support, and Johannes Macher for the help with fitting the experimental data using Python. PCCL is funded by the Austrian Government and the State Governments of Styria, Lower Austria and Upper Austria.

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© 2022 by the authors.

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