A comprehensive 3‐D analysis of polymer melt flow in slit extrusion dies

Abstract

An understanding of flow behaviour of polymer melts through a slit die is extremely important for optimizing die design and, consequently, for die performance in processing polymer sheets and films. In view of the complex nature and the physical properties of polymer melts as well as of die geometries, such as coat-hanger dies, no simple mathematical formulae can be used to compute the flow regimes within dies. This paper illustrates the development of a three-dimensional (3-D) computer model of an example of a coat-hanger die design using the computational fluid dynamics package, FIDAP, based on the finite element method. A difference of only 3.7% was found when comparing the velocity distribution at the die exit obtained from the 3-D simulation with that calculated using a twodimensional analytical design procedure, indicating that full 3-D analysis seems to be unnecessary. However it has been shown that unwanted flow phenomena and production problems can be ameliorated by means of visualization and the detailed information obtained from computer simulations. Comparative simulation results with polymers of different rheological properties in the same die are also described. The comprehensive analyses provide a means of interpretation for flow behavior, which allows modification of the die geometry for optimal design.

Control Model for an Elastomer Extrusion Process Obtained via a Comparative Analysis of Data Mining and Artificial Intelligence Techniques

“…Extrusion is a complex process and the behaviour of several factors which might prevent profiles of the required size and design from being obtained must be monitored [1,2] . The most important of these factors include uneven flow, distortions in extruded material, profile geometry and certain parameters such as temperature, pressure and ram speed.…”

Modelling of an elastomer profile extrusion process using support vector machines (SVM)

“…has revolutionised the study of extrusion processes for different materials (Huang and Huang, 2006;Huang et al, 2004;Caslin and Alan, 2005;Kleiner and Schikorra, 2006;Jansson et al, 2005;Fung and Kang, 2005;Tan et al, 2004). In particular, neuronal networks, due to their capacity to model non-linear systems have been used in all types of extrusion processes (Li et al, 2004;Hans Raj et al, 2000;Huang and Lu, 2005;Li and Bridgwater, 2000;Qi et al, 1999;Wu and Hsu, 2002) (now, robust neuronal networks are currently used in spite of outliers to improve prediction capacity (Pernía et al, 2005)).…”

Rheological and dynamic mechanical characteristics of rotationally moldable linear low‐density polyethylene fumed silica nanocomposites

“…The uses of polyethylene glycols (PEG) as well as PEG‐based esters at concentrations from 0.1 to 0.5 wt% reduced the sintering time of the polymer melt but affected free‐flow properties of the LLDPE powder . A combination of the PEG and PEG‐based esters with FS reduced the amount of trapped gasses, decreased the sintering time while preserving the good free‐flow behavior of the LLDPE powder .…”