Capillary rheometry of polymer melts – Simulation and experiment
نویسندگان
چکیده
This paper discusses shear viscosity measurements of polymer melts by the capillary rheometer. Particular emphasis is placed on investigating the effects of viscous heating and pressure dependence of viscosity in capillary flows. The capillary flow problem is addressed by means of numerical simulation using the finite element method to solve the equations of continuity, momentum and energy along with the viscosity model that accounts for the dependence on shear rate, temperature and pressure. Simulations clearly reveal that viscous heating and pressure dependence of viscosity can have a considerable impact on capillary rheometer experiments. On the other hand, as far as the pressure drop over the capillary is concerned, it is possible that these two contributing factors compensate for each other. Selected experimental data from the capillary rheometer are also presented and discussed in connection with the simulated results.
منابع مشابه
‘Beads on a String’ Structures and Extensional Rheometry using Jet Break-up
1. Introduction: Surface tension driven break-up of cylindrical fluid elements into droplets plays a crucial role in the use or processing of many multicomponent complex fluids like paints, inks, insecticides, cosmetics, food, etc [1, 2]. These industrial fluids are typically formulated using dilute polymer solutions, and are exposed to a wide range of shear and extension rates. Since the polym...
متن کاملcomparison between to versions of the SAFT EOS in the study of PVT and VLE phase behavior of pure polymer melts and binary polymer solutions
متن کامل
Control of the sharkskin instability in the extrusion of polymer melts using induced temperature gradients
Flow instabilities occur in a variety of commercial polymer processing operations including extrusion, film blowing, fiber spinning and coating. During the extrusion of molten polymer through capillary or slit die geometries, a transition from a smooth surface to a nearly periodic ridge-like surface distortion has been observed at a critical shear rate or wall shear stress (Petrie and Denn 1976...
متن کاملA comparison of neutron scattering studies and computer simulations of polymer melts
Neutron scattering and computer simulations are powerful tools for studying structural and dynamical properties of condensed matter systems in general and of polymer melts in particular. When neutron scattering studies and quantitative atomistic molecular dynamics simulations of the same material are combined, synergy between the methods can result in exciting new insights into polymer melts no...
متن کاملThe effect of step-stretch parameters on capillary breakup extensional rheology (CaBER) measurements
Extensional rheometry has only recently been developed into a commercially available tool with the introduction of the capillary breakup extensional rheometer (CaBER). CaBER is currently being used to measure the transient extensional viscosity evolution of mid to low-viscosity viscoelastic fluids. The elegance of capillary breakup extensional experiments lies in the simplicity of the procedure...
متن کامل