NEW IN-LINE VISCOSITY MEASUREMENT FOR VERY HIGH VISCOSITY PRODUCTS APPLICATION TO PLASTIC AND ELASTOMER EXTRUDER

摘要

Numerous materials such as polymers are solids under standard conditions but pasty inrnprocess conditions. In a laboratory at ambient temperature and low shear rates, these productsrncan have viscosities comprised between 10~3 Pa.s and 10~(12) Pa.s. These polymers, plastics orrnelastomers must have the capacity to flow in the process and have viscosities inferior torn10~3 Pa.s in order to be extruded and shaped. This is made possible with the effects ofrntemperature and shear rate on the properties of these Non-Newtonian products. Typicalrnproducts concerned are polymers for extrusion and injection.rnThe plastic extrusion process applies to liquid and melted polymers. It starts with the materialrnbeing fed to the extruder, melted and then pushed through the system by a rotating screw. Thernliquid polymer then goes into a die where it is extruded under high pressure according to arnmolding which will give a specific shape to the final part. Adjustments of the ingredients inrnthe polymer, melting temperature, extrusion speed and pressure are many of the parametersrninfluencing the final quality of the extruded polymer. Viscosity is a physical property of thesernnon-Newtonian polymers and is correlated to intrinsic viscosity, melt flow index and others.rnIn-line viscosity control of the melted polymer before the extrusion die is the ideal solution tornobtain precious information in order to set up and adjust the optimum extrusion parameters,rnand consequently realize process savings in material, labor, time and money.rnIn this paper the state of the art of available technologies for viscosity measurement of veryrnhigh viscosities in extrusion processes will be reviewed. Since none of the existing solutionsrn provide in-line systems including a viscosity sensor, the idea of using the vibrating principlernat resonance frequency, a renowned principle in viscosity measurement, inside the extrusionrnpipe will be described. This paper will then describe the design of the sensor, its integrationrnin extrusion dies and provide results on very high viscosity fluids. Finally, we will considerrnpotential applications of this technology in very high viscosities petroleum products (asphalts,rnbitumens, residues…).