Process And Mechanism Study Of Polymer Solids Deformation In Vane Extruder

Extruder is a typical machine used to melt polymer for further processing. However, formost polymer processing machines, such as singe-screw extruder or twin-screw extruder,solids-fed and melting are determined by a drag-induced mechanism, depending on thefriction coefficient of material properties and the friction coefficient between screw’s innersurface and material, leading to a long thermo-mechanical history. To overcome thesedisadvantages, a novel non-screw equipment for polymer processing known as vane extruderwas designed by Qu.Polymer solids are subjected to stressing that force them to deform, leading a temperaturerise, which firmly affects material’s transportation and melting. This paper examined polymersolids deformation taking place in the vane extrusion by visualization experiments anddeveloped mathematical model, and subsequently discussing the effect of material parametersand processing conditions on the solid deformation with theoretical and experimentalmethods.With a assembled vane extruder, solid deformation of PP particles under differentoperational conditions was investigated. It is shown that polymer positive displacementconveying mechanism makes polymer solids severely compacted, leading to solidsdeformation, which mainly happens in the first vane units of vane extruder.Based on the experiments, polymer deformation model were developed and verified. It wasshown that solids deformation has close relationship with operation condition, frictioncoefficient, as well as material properties. More specially, low temperatures and high rotorspeeds can lead to severe solids deformation, resulting in a temperature rise of solids. Solidsdeformation of non-crystalline material is more larger than that of crystalline material. Solidsdeformation of small polymer pellets can give rise to a higher temperature rise than pellets.The addition of epoxidized soybean oil (ESO) can reduce friction coefficient, which canobtain a lower temperature rise during solids deformation. The above experimental andtheoretical models can guide the optimizing of device and process, and further develop thepotential application of vane extruder.