On the Modeling of the Phase Separation of a Gelling Polymeric Mixture

The gelation of polymer mixtures under constant cooling rate has been found to be an attractive product structuring mechanism for the food industry. As applications become wider, a predictive method for the process is warranted. To this end, we apply the so-called ‘

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concept’ in a CFD module for the modeling for microstructure formation of gelling mixtures, where moments of the particle size distribution are evaluated using the local flow conditions as obtained from CFD simulations for the processes considered. The major driving force for these processes is the competition between phase separation, gelation and hydrodynamic phenomena such as break-up and coalescence. Based on theoretical investigations, analytical expressions for the source terms representing the hydrodynamics (break up and coalescence of the droplets) as well as the gelation process were produced. Constitutive models are developed to incorporate the effects of phase separation and gelation on the rheology of the phases. The simulations for different cooling rates clarified the inter-relationships between the competitive mechanisms by depicting the time interval of the domination of each.