An experimental study on shear stress characteristics of polymers in plasticating single‐screw extruders

Abstract

Frictional forces (for temperatures less than the melting or devitrification temperature) and viscous forces (for higher temperatures) have important roles on solids conveying and melting processes in plasticating single-screw extruders. These forces are related to the shear stresses at polymer-metal interfaces. For temperatures at which the frictional forces are the main factor for the shear stresses, it is experimentally difficult to obtain the shear stresses at the polymer-metal interface. The interpretation of the data has further complications due to the frictional energy dissipation at the polymer-metal interface. An instrument called the Screw Simulator was used for further understanding of shear stresses at the polymer-metal interface and comparison of melting fluxes of different resins. This article presents the shear stress and melting flux measurements for low density polyethylene (LDPE), linear LDPE (LLDPE), acrylonitrile butadiene styrene (ABS), and high-impact polystyrene (HIPS) resins as a function of sliding velocity and interface temperature at a fixed pressure of 0.7 MPa. The relationship between the experimental data and the extrusion process is also discussed.

Melting rate of a single screw extruder with a grooved melting zone

“…The Melting Flux for LDPE was simulated under three different conditions, and the results were plotted together with experimental information found in the literature [8], see It is important to note that the experimental information comes from a screw simulator with a smooth cylinder, which means the information does not describe the melting rate of a grooved extruder. However, it serves as a reference point, to judge the results of the mathematical model, when compared to a conventional extruder.…”

Analysis of a Single Screw Extruder with a Grooved Plasticating Barrel – Part I: The Melting Model

“…7represents information reported by Altinkaynak et al (2009). 7represents information reported by Altinkaynak et al (2009).…”

“…Comparison of calculated melting fluxes with those measured for LDPE in as crew simulator with smooth cylinder(Altinkaynak et al, 2009) International Polymer Processing downloaded from www.hanser-elibrary.com by Kungliga Tekniska on August 25Melting rate as afunction of: A) relative velocity, B) melting angle, C) barrel temperature, D) polymer feedstock temperature, E) groove angle, F) groove width, G) groove depth, H) number of grooves, I) melt film thickness at the end of zone 1, and J) solid bed width. Calculation according to the experimental design shown in…”

Three dimensional finite element simulation of polymer melting and flow in a single-screw extruder : optimization of screw channel geometry

“…Part of this section is from a preprint of an article published in [3] (See Appendix A for the copyright agreement). Frictional forces (for temperatures less than the melting or devitrification temperature) and viscous forces (for higher temperatures) have important roles on solids conveying and melting processes in plasticating single-screw extruders.…”

“…For all resins, two local maxima in the shear stress curves were observed; one was near the glass transition temperature at about 150°C, and the other at about 240°C. It is interesting to note that this kind of shear stress behavior was not observed for other amorphous materials such as acrylonitrile butadiene styrene (ABS) terpolymer and high-impact polystyrene (HIPS) resin[3,8,53,[67][68][69][70]. Two stress maxima, however, are apparent in the PC resin data measured by Mount and Chung[39].…”