Rheology of Multiphase Polymer Systems using Novel „Melt Rigidity” Evaluation Approach

Multiphase polymer systems like blends, composites and nanocomposites exhibit complex rheological behaviour due to physical and also possibly chemical interactions between individual phases. Up to now, rheology of heterogeneous polymer systems has been usually described by evaluation of viscosity curve (shear thinning phenomenon), storage modulus curve (formation of secondary plateau) or plotting information about dumping behaviour (e.g. Van Gurp-Palmen-plot). On the contrary to evaluation of damping behaviour, „melt rigidity“ approach has been introduced for description of physical network of rigid particles in polymer matrix as relation of ∫G´/∫G´´ over specific frequency range. This approach has been experimentally proved for polymer nanocomposites in order to compare shear flow characteristics with elongational flow field. In this contribution, LDPE-clay nanocomposites with different dispersion grades (physical networks) have been prepared and characterized by both conventional as well as novel „melt rigidity“ approach.