Cross-linked Poly(Lactide) and Poly(ε-caprolactone) with the Addition of Ethyl Ester L-Lysine Triisocyanate: Theoretical Modelling of the Rheological Behaviour

In order to successfully model the dynamic rheological behaviour of polymeric materials, appropriate frequency dependant computational formulae need to be employed. The fractional calculus was introduced to relate stress to strain fields describing viscoelastic phenomena [1]. To describe the experimental data of materials which exhibit symmetrical loss peak behaviour or contain symmetrical distinct processes in the frequency spectrum, the Cole-Cole or four-parameter fractional derivative Zener function model can be applied [2]. In addition, in more complicated systems, the experimental rheological behaviour is the superposition of more than one individual processes which can later be identified by their characteristics [3]. Similar semi-empirical mathematical formulae can be employed to model the dielectric response of materials including asymmetrical processes [4].