Wall slip and extrudate distortion of three polymer melts

2003 ◽  
Vol 47 (3) ◽  
pp. 683-699 ◽  
Author(s):  
Dilhan M. Kalyon ◽  
Halil Gevgilili
Keyword(s):  
Polymer Melts ◽  
Wall Slip ◽  
Extrudate Distortion

Stochastic chain simulation of wall slip in entangled polymer melts

2007 ◽  
Vol 51 (3) ◽  
pp. 451-464 ◽  
Author(s):  
Fang Xu ◽  
Morton M. Denn ◽  
Jay D. Schieber
Keyword(s):  
Polymer Melts ◽  
Wall Slip ◽  
Entangled Polymer ◽  
Entangled Polymer Melts

Pressure dependent wall slip of wood flour filled polymer melts

2017 ◽  
Vol 247 ◽  
pp. 178-187 ◽  
Author(s):  
Valentina Mazzanti ◽  
Francesco Mollica
Keyword(s):  
Polymer Melts ◽  
Wood Flour ◽  
Wall Slip ◽  
Filled Polymer

Experimental study and molecular dynamics simulation of wall slip in a micro-extrusion flowing process

2011 ◽  
Vol 225 (5) ◽  
pp. 1175-1190 ◽  
Author(s):  
D Zhao ◽  
Y Jin ◽  
M Wang ◽  
M Song
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulation ◽  
Slip Velocity ◽  
Polymer Melts ◽  
Critical Shear Stress ◽  
Wall Slip ◽  
Dynamics Simulation ◽  
Desorption Mechanism ◽  
Adsorption Desorption

Wall slip is one of the most important characteristics of polymer melts’ elasticity behaviours as well as the most significant factor which affects the flow of polymer melts. Based on the traditional Mooney method, through a double-barrel capillary rheometer, the relationship between velocities of wall slip, shear stress, shear rate, diameters of dies, and temperature of polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), and polymethylmethacrylate (PMMA) is explored. The results indicate that the velocities of the wall slip of PP and HDPE increase apparently with shear stress and slightly with temperature. Meanwhile, the rise of temperature results in the decrease of critical shear stress. The wall-slip velocities of PS and PMMA are negative which means that the Mooney method based on the adsorption–desorption mechanism has determinate limitation to calculate the wall-slip velocity. Based on the entanglement–disentanglement mechanism, a new wall-slip model is built. With the new model, the calculation values of velocity of PP and HDPE correspond to the experimental values very well and the velocities of PS and PMMA are positive. The velocities of PS and PMMA increase obviously with the rise of shear stress. The rise of temperature results in the increase of velocity and decrease of critical shear stress. Then, the molecular dynamics simulation is used to investigate the combining energy between four polymer melts and the inside wall. The results show that at the given temperature and pressure, the molecules of PS and PMMA combine with atoms of the wall more tightly than those of PP and HDPE which means when wall slip occurs, the molecules of PS and PMMA near the wall will adsorb to the surface of the wall. However, those of PP and HDPE will be easy to slip. Therefore, the wall-slip mechanism of PP and HDPE is the adsorption–desorption mechanism, and that of PS and PMMA is the entanglement–disentanglement mechanism. According to the different wall-slip mechanisms of four polymers, an all-sided calculation method of wall-slip velocity is raised which consummates the theory of wall slip of polymer melts.

Extrusion of Polymer Melts and Melt Flow Instabilities. I. Experimental Study of Capillary Flow and Extrudate Distortion

1969 ◽  
Vol 42 (3) ◽  
pp. 675-681 ◽  
Author(s):  
Gene A. Bialas ◽  
James L. White
Keyword(s):  
Experimental Data ◽  
Polymer Melts ◽  
Capillary Flow ◽  
Flow Instability ◽  
Research Effort ◽  
Flow Instabilities ◽  
Melt Flow ◽  
Considerable Research ◽  
Extrudate Distortion ◽  
First Descriptions

Abstract The extrusion of molten plastics, elastomers and fibers represent an important industrial operation. The rate of extrusion of melts through dies is limited by the onset of a flow instability. This phenomenon consists of a change in flow from uniform to irregular that results in the production of rough and distorted extradates drastically different from the smooth cylinders obtained at lower rates. Extrusion melt flow instability is observed in the entire spectrum of polymer melts ranging from silicone gums through nylon and polyolefin plastics to raw elastomers. Since the first descriptions of this phenomena in the 1940's considerable research effort has been expended in this area with limited agreement. It is the purpose of part I to: (1) present new experimental data on capillary flow of polymer melts and extrudate distortion, and (2) to review critically the literature on extrudate distortion.

Wall slip in polymer melts: A pseudo-chemical model

1998 ◽  
Vol 42 (3) ◽  
pp. 581-601 ◽  
Author(s):  
Davide A. Hill
Keyword(s):  
Polymer Melts ◽  
Wall Slip ◽  
Chemical Model

Size Design of Capillary and Barrel of Multi-Function and All-Electric Rheometer

2013 ◽  
Vol 853 ◽  
pp. 536-540
Author(s):  
Xiang Gang Li ◽  
Yue Jun Liu ◽  
Yi Chen ◽  
Xiao Yuan Zhou ◽  
Hui Tan ◽  
...  
Keyword(s):  
Shear Rate ◽  
Polymer Melts ◽  
Nonlinear Viscoelasticity ◽  
Wall Slip ◽  
High Shear Rate ◽  
High Shear ◽  
Rate Range ◽  
Pressure Correction ◽  
Precise Calculation ◽  
Entrance Pressure

Multi-function and all-electric rheometer (MAR) was designed by the authors to study the nonlinear viscoelasticity of polymer melts at high shear rate. It is important to design suitable size of capillary and barrel because it is the calculation basis for some other important parts and determines the shear rate range of MAR. Considering the shear rate range, the entrance pressure correction and the wall slip correction, the length and diameter of capillary and barrel of MAR were designed through particular analysis and precise calculation.

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