ABSTRACT
Thermal oxidative ageing is limiting the life time of rubber products. Beside environmental factors, the micro-structure of used polymers, the cross linking, fillers and additives are influencing components. Especially, the chemical degradation of the polymer network influences highly the mechanical behaviour. In this study we concentrate on characterising the ageing of an elastomer model compound (low- and high-cross linked EPDM) based on parameter identifications of the Dynamic Flocculation Model (DFM). The different compounds are tested in multi-hysteresis experiments in order to obtain an insight in the cyclic mechanical response.
The DFM is developed based on the extended non-affine tube model to capture the basic behaviour of the rubber matrix and also on the entropic driven material behaviour of the polymer network with the polymer-filler and filler-filler interaction. The latter is considering the breakage and re-agglomeration of filler clusters in the polymer matrix during repeated deformation cycles. Therefore, the DFM is capable to describe physically motivated effects in elastomers. The parameters of the model provide an insight of the structure of the elastomers, and are therefore investigated for different ageing states. In the evaluation of the model parameters for those different states, the DFM is examined if it is a suitable candidate for extension to describe the ageing phenomena.
