MODELING the AVERAGE SHEAR RATE IN A CO-ROTATING TWIN SCREW EXTRUDER

The rapid estimation of the average shear rate encountered by the material as it flows along the screw elements of a corotating twin-screw extruder is a key point for many applications. In this paper, two methods of evaluation are presented that allow the calculation of the average shear rate as a function of the screw geometry, feed rate, and screw speed. A comparison is made between the approximate and exact methods. It is shown that it is crucial to take into account the shear component due to the pressure flow, especially in the left-handed screw elements.

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AVERAGE SHEAR RATE IN A TWIN-SCREW EXTRUDER AS A FUNCTION OF DEGREE OF FILL, FLOW BEHAVIOR INDEX, SCREW SPEED AND SCREW CONFIGURATION

Journal of Food Process Engineering ◽

10.1111/j.1745-4530.2009.00381.x ◽

2010 ◽

Vol 34 (4) ◽

pp. 961-982 ◽

Cited By ~ 8

Author(s):

M. SUPARNO ◽

K.D. DOLAN ◽

P.K.W. NG ◽

J.F. STEFFE

Keyword(s):

Shear Rate ◽

Flow Behavior ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Screw Speed ◽

Flow Behavior Index ◽

Average Shear Rate ◽

Average Shear ◽

Twin Screw ◽

Behavior Index

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Properties of EPDM/PP thermoplastic vulcanizates produced by an intermeshing-type internal mixer comparing with a co-rotating twin-screw extruder

Journal of Polymer Engineering ◽

10.1515/polyeng-2018-0162 ◽

2019 ◽

Vol 39 (2) ◽

pp. 143-151

Author(s):

Wattana Teppinta ◽

Banja Junhasavasdikul ◽

Nattapong Nithi-Uthai

Keyword(s):

Shear Rate ◽

Elastic Recovery ◽

Mechanical Energy ◽

Cross Linking ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Lower Shear ◽

Twin Screw ◽

Lower Shear Rate ◽

Internal Mixer

Abstract A unique technology for producing thermoplastic vulcanizate (TPV) has been developed using an intermeshing-type internal mixer (ITM). TPV produced by the ITM was compared with that produced using a co-rotating twin screw extruder (Co-TSE) to assess the former’s commercial possibilities. TPV, originating from ethylene-propylene-diene monomer (EPDM) and polypropylene (PP), was produced by both machines with equal filled volumes, same shear rate, and same specific mechanical energy. Results indicate that ITMs can be used to produce TPV with mechanical properties comparable to those of TPV produced by Co-TSE. TPV can be produced with a lower shear rate with ITM compared to Co-TSE. A long residence time can be maintained in the mixing chamber of the ITM, allowing high conversion of the cross-linking reaction and resulting in better elastic recovery properties due to the higher cross-linking density. However, this resulted in higher viscosity of TPV produced by ITM.

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Numerical Simulation of Mixing Performance of Intermeshing Co-Rotating Tri-Screw and Twin-Screw Extruders

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.468-471.2211 ◽

2012 ◽

Vol 468-471 ◽

pp. 2211-2214 ◽

Cited By ~ 1

Author(s):

G. Wang ◽

X.Z. Zhu ◽

Chun Yi Sun

Keyword(s):

Shear Rate ◽

Polymer Melt ◽

Polymer Processing ◽

Mixing Efficiency ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Twin Screw Extruders ◽

Mixing Performance ◽

Twin Screw ◽

Dispersive Mixing

Parallel arranged tri-screw extruder (PATSE) is a new machine of polymer processing and first manufactured in recent years in China. Compared with the traditional twin-screw extruder, PATSE adds a screw, and added an intermeshing region. It is well known that material going though intermeshing region will acquire higher shear rate and stretching rate, which is beneficial to mixing processing. In order to know the mixing performance in cross-section for PATSE, polymer melt flow field simulation and mixing simulation were conducted on PATSE with 2D model and a Carreau flow model to evaluate velocity profiles, particle trajectories, max shear rate, max stretching rate, dispersive mixing, distributive mixing, segregation scale, length of stretch, mixing efficiency with the commercial CFD package Polyflow and compared with those of twin screw extruder (TSE). The results show that PATSE has better mixing performance than TSE.

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