Modelization of flow electrification in a polymer melt

Flow electrification of polymer melts is an important side effect of polymer processing. The studies dealing with this phenomenon are seldom and most of the scientific work has been focused on flow electrification of aqueous and insulating Newtonian liquids. From that prior art it is well established that the flow electrification in Newtonian liquids is a consequence of the formation of an ionic double layer. Convection of this layer induces the electrification of the liquid at the outlet of the pipe. In those models, the key parameters governing the flow electrification are thus the intrinsic electrical properties of the polymer and the flow characteristics. In this work, we reconsider the assumptions made previously and we propose a new approach to modelise the flow electrification in the particular case of non-Newtonian polymer materials in laminar flow conditions. We establish that, a key parameter for the electrification quantification in the polymer melt is the shape of the velocity profile. Additionally, in some cases, we show that a slip velocity at the polymer/die wall interface must be considered to describe accurately the electrification. As a consequence, we deduce that the slip velocity at the interface can be calculated by measuring the electrification: this work gives an alternative manner to measure the slip velocity during polymer flow

Determination of interfacial tension of polymer melts by dynamic shear measurements

cited By 51International audienceThe linear viscoelastic behavior of two-phase polymer blends in the melt is characterized by high values of storage modulus at low frequencies and by long relaxation times. These rheological properties depend directly on the interfacial tension α between the two polymers. Dynamic shear measurements provide, therefore, a method to determine α without perturbation of the system. The frequency dependence of dynamic moduli could be accounted for with an emulsion model of two viscoelastic liquids. Experimental data for G′ (ω) and G″ (ω) on poly(dimethylsilox (PDMS)/poly (oxyethylene-diol) (POE-DO) blends have been found to be in good accordance with the emulsion model and the value of interfacial tension found in the literature for this system. © 1991