scholarly journals Three-dimensional characterization of dispersive mixing in single screw extruders

2016 ◽  
Author(s):  
Thomas Erb ◽  
Oguz Celik ◽  
Christian Bonten
Keyword(s):  
Three Dimensional ◽  
Single Screw ◽  
Single Screw Extruders ◽  
Dispersive Mixing ◽  
Screw Extruders

A quantitative approach to assess the mixing ability of single-screw extruders for polymer extrusion

2012 ◽  
Vol 32 (2) ◽  
Author(s):  
Natália Domingues ◽  
António Gaspar-Cunha ◽  
José António Covas
Keyword(s):  
Immiscible Liquid ◽  
Operating Conditions ◽  
Mixing Efficiency ◽  
Single Screw ◽  
Liquid Systems ◽  
Single Screw Extruders ◽  
Mixing Ability ◽  
The Individual ◽  
Dispersive Mixing ◽  
Screw Extruders

Abstract Models to predict the evolution of the morphology of immiscible liquid-liquid systems and of solid agglomerates dispersion in single-screw extruders were adapted to compute global distributive and dispersive mixing indices. Using these indices, the direct assessment of the mixing ability of a given screw or a comparison of distinct screws becomes readily available. In the case of liquid-liquid systems, the degree of distributive mixing is computed from the extent of deformation of the individual drops, whereas the degree of dispersive mixing is determined by the reduction in drop size. For solid-liquid systems, distributive mixing is quantified by a normalized Shannon entropy, whereas dispersive mixing is defined from the extent of size reduction. The effect of material properties, operating conditions, and geometry of the screw and die is investigated. Finally, the indices are used to determine (via optimization) the operating conditions and the screw geometry that maximize the mixing efficiency.

Investigation of Mixing Performance in the Extruder with Embedded Planetary-Screws

2013 ◽  
Vol 781-784 ◽  
pp. 2809-2816
Author(s):  
Liang He ◽  
Bai Ping Xu ◽  
Hui Wen Yu ◽  
Xiao Long Wang ◽  
Gang Xue
Keyword(s):  
The Novel ◽  
Screw Extruder ◽  
Mixing Performance ◽  
Single Screw ◽  
Single Screw Extruder ◽  
Laminar Mixing ◽  
Single Screw Extruders ◽  
Twin Screw ◽  
Screw Extruders

The novel geometrical configuration of embedded planetary-screws is proposed in the paper. The corresponding numerical simulation and the experimental investigation are carried out to characterize the mixing performance. Adopting commercial software FLUENT, the simplified physical model is presented with the boundary conditions imposed by UDF codes which are developed by us. Compared with the traditional single screw extruder, the flow and mixing are primarily investigated by using particle tracking technology. The sensitivity to initial positions is found in the novel screw configuration, which is caused by the periodic perturbation of planetary-screws. In contrast, the traditional laminar mixing occurs in single screw extruders. Compared with the traditional twin screw extruder, the experimental characterization of filled system of adding active nanometer CaCO3 into LLDPE matrix is conducted. No obvious difference in dispersion of CaCO3 is found when the extrusion samples are observed through scanning electron microscopy (SEM), on the condition that the both extrusion outputs are equal. The shear rate in the novel screw configuration is relatively smaller, and the extrusion characteristic is more excellent.

Modelling of Mixing in Single Screw Extruders

2006 ◽  
Vol 514-516 ◽  
pp. 1409-1413
Author(s):  
Natália Domingues ◽  
António Gaspar-Cunha ◽  
José A. Covas
Keyword(s):  
Computer Modelling ◽  
Polymer Processing ◽  
Liquid System ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Single Screw Extruders ◽  
Processing Techniques ◽  
New Applications ◽  
Dispersive Mixing ◽  
Screw Extruders

Polymer extrusion is one of the most important polymer processing techniques. Modelling of the phenomena developing inside single screw extruders enabled the development of commercial software which can be used to study the performance of existing systems and to define the equipment characteristics for new applications. Although mixing is one of the most important performance measures of extrusion, it is usually disregarded in the available programs. Consequently, in this work mathematical models for quantifying mixing in single screw extruders are developed and subsequently inserted in a global computer modelling program of single screw extrusion. The mixing model quantifies distributive and dispersive mixing and coalescence mechanisms in a liquid-liquid system. This is accomplished by calculating the variation of the thickness of drops considered to be suspended in the polymeric matrix, taking into account the rate and drop break-up time and the coalescence probability. The influence of several parameters, such as viscosities, initial drop dimension, screw speed and barrel temperature, are examined

scholarly journals Numerical Simulation of Polymer Solutions in a Single-Screw Extruder

2019 ◽  
Vol 9 (24) ◽  
pp. 5423
Author(s):  
Aidar Kadyirov ◽  
Rustem Gataullin ◽  
Julia Karaeva
Keyword(s):  
Polymer Solutions ◽  
Three Dimensional ◽  
Extrusion Process ◽  
Working Fluid ◽  
Screw Extruder ◽  
Single Screw ◽  
Single Screw Extruder ◽  
Single Screw Extruders ◽  
Speed Rotation ◽  
Screw Extruders

Single-screw extruders are the most common equipment used for polymer extrusion. The study of the hydrodynamics of a polymer melts flow in the extruder channel is the basis for modeling and understanding the extrusion process. In general form, the extruder includes a straight section with a screw installed in it. In this study, the three-dimensional mathematical modeling of the polymer solutions flow in the metering zone of a single-screw extruder is performed. The influences of the screw geometry (L/D2 = 1…3) on the flow structure and the pressure drop are analyzed under a speed rotation up to 60 rpm. Aqueous solutions of 0.5% polyacrylamide (0.5% PAA) and 1.5% sodium salt of carboxymethyl cellulose (1.5% CMC) are considered as the working fluid.

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