Extension‐dominated improved dispersive mixing in single‐screw extrusion. Part 2: Comparative analysis with twin‐screw extruder

2020 ◽  
Vol 138 (5) ◽  
pp. 49765
Author(s):  
Vivek Pandey ◽  
Hao Chen ◽  
Jiaxin Ma ◽  
João M. Maia
Keyword(s):  
Comparative Analysis ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Dispersive Mixing

Twin-Screw Extrusion Modelling

2006 ◽  
Vol 45 ◽  
pp. 436-441 ◽  
Author(s):  
P.A. McGuire ◽  
S. Blackburn ◽  
E.M. Holt
Keyword(s):  
Temperature Correction ◽  
Force Balance ◽  
Rheological Parameters ◽  
Twin Screw Extruder ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Single Screw Extrusion ◽  
Heating Effects ◽  
Screw Extrusion ◽  
Twin Screw

A mathematical model has been derived to describe the pressure drop along the conveying and reverse sections of a partly full, fully intermeshing co-rotating twin-screw extruder. The model extends previous work on single screw extrusion, whereby the Benbow-Bridgwater model of paste rheology is combined with a force balance on a plug of paste. Experiments to verify the model have been carried out using a laboratory scale twin-screw extruder fitted with a hydraulic feeder and a modified barrel section allowing the collection of pressure data at numerous points along the extruder. Initial results suggested that the model was able to correctly predict the trends observed but underestimated the absolute values of the pressure. This was attributed to a change in the rheology of the paste due to viscous heating effects. Further experimental work was carried out to determine the relationship between the rheological parameters and temperature; this allowed a temperature correction to be made to the initial data after which the agreement with the predictions was greatly improved.

N-Lamina Model of Extrusion Pressure of Non-Plug Flow Solid Conveying in Feeding Section by Single-Screw Extrusion Molding

2011 ◽  
Vol 221 ◽  
pp. 271-277 ◽  
Author(s):  
Chun Hui Liu ◽  
Jian Hua Qin ◽  
Da Li Shi
Keyword(s):  
Plug Flow ◽  
Extrusion Pressure ◽  
Powder Materials ◽  
Screw Extruder ◽  
Molding Process ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Single Screw Extruder ◽  
Screw Extrusion ◽  
Solid Conveying

While extrusion molding with single-screw extruder, extrusion pressure comes into being from feeding section; it is one of the basic conditions to ensure that extrusion process can be carried on normally, in order to ensure molding process goes smoothly, it must meet the following requirement: extrusion pressure generated during the process must be sufficient. Therefore it has certain engineering significance to design structure of a single screw correctly that a mathematical model for formation of extrusion pressure during single-screw extrusion molding will have to be established. This paper conducted a research on theory of extrusion pressure when powder of pure UHMWPE resin is still in feeding section by molding in barrel of the single screw extruder specially designed for pure UHMWPE, and established a n-lamina model of powder materials or grain materials which is in feeding section and at the state of non-plug flow solid conveying, and it provided a method to calculate extrusion pressure of the n-lamina model, thus it enriched and perfected theory of single-screw extrusion molding.

scholarly journals Evaluation of Dispersive Mixing Performance of Special Rotor Segments in an Intermeshing Co-rotating Twin-Screw Extruder

Seikei-Kakou ◽  
2012 ◽  
Vol 24 (5) ◽  
pp. 279-285
Author(s):  
Sayaka Yamada ◽  
Kazuhisa Fukutani ◽  
Yasuaki Yamane ◽  
Kazuo Yamaguchi
Keyword(s):  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Mixing Performance ◽  
Twin Screw ◽  
Dispersive Mixing

Plasticating Single-Screw Extrusion

2006 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Solid Polymer ◽  
Heat Of Fusion ◽  
Screw Extruder ◽  
Twin Screw Extruders ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Single Screw Extruder ◽  
Single Screw Extruders ◽  
Twin Screw ◽  
Screw Extruders

There are two types of extruder: (1) single-screw extruders and (2) twin-screw extruders. The single-screw extruder is one of the most important pieces of equipment in the processing of thermoplastic polymers. Accordingly, during the past three decades, many attempts have been made to analyze the performance of single-screw extruders using different degrees of mathematical sophistication (Cox and Fenner 1980; Donovan 1971; Edmondson and Fenner 1975; Elbirli et al. 1983, 1984; Halmos et al. 1978; Han et al. 1991a, 1991b, 1996; Lee and Han 1990; Lindt 1976; Lindt and Elbirli 1985; Shapiro et al. 1976; Tadmor 1966; Tadmor and Klein 1970; Tadmor et al. 1967). There are two types of single-screw extruders: (a) plasticating and (b) melt-conveying. The plasticating single-screw extruder conveys a solid polymer from the feed section to the melting section, where most of the melting (or softening) occurs, and then transports the melted or softened polymer to a shaping device (e.g., dies and molds). The meltconveying extruder does not include a melting section; it simply transports an already softened polymer to a shaping device (e.g., rubber extruder). Single-screw extruders are used for various purposes, such as melting and pumping, compounding with an additive(s) or filler, cooling and mixing, removing residual monomers or solvents in polymer (i.e., polymer devolatilization), and cross-linking reactions. Single-screw extruders are simple to operate and relatively inexpensive as compared with twin-screw extruders. However, there are situations where a single-screw extruder cannot function as effectively as a twin-screw extruder. In the design of plasticating single-screw extruders, one needs information on (1) the physical and thermal properties of polymers (e.g., friction coefficient between the solid polymer and barrel wall, thermal conductivity of polymer, specific heat as a function of temperature, melting point of polymer, and heat of fusion of polymer) and (2) rheological properties of polymers as functions of shear rate and temperature. Due to the complexity involved in the design of extruders, it is highly desirable for one to establish relationships between material variables and processing variables.

Discussion on N-Lamina Model of Non-Plug Flow Solid Conveying in Feeding Section by Single-Screw Extrusion Molding

2012 ◽  
Vol 501 ◽  
pp. 583-588
Author(s):  
Chun Hui Liu ◽  
Da Li Shi ◽  
Yan Yang Wu ◽  
Jian Hua Qin
Keyword(s):  
Compressive Stress ◽  
Plug Flow ◽  
Screw Extruder ◽  
Molding Process ◽  
Single Screw ◽  
Single Screw Extrusion ◽  
Single Screw Extruder ◽  
Screw Extrusion ◽  
Solid Conveying

This paper analyzed several important issues in theory of non-plug flow solid conveying, which is about the extrusion molding process of the single screw extruder, they are mainly: compressive stress on the front and rear ends of the surface, and ; an increase trend of compressive stress , ; pressure in feeding compression section of the screw, .

Effect of Screw Assembly on the Properties of Glass Fiber-Reinforced Nylon-66 Composite

2012 ◽  
Vol 562-564 ◽  
pp. 443-446
Author(s):  
Zhao Yin Jiang ◽  
Ya Dong He ◽  
Chun Ling Xin ◽  
Gang Li
Keyword(s):  
Mechanical Property ◽  
Comparative Analysis ◽  
Glass Fiber ◽  
Fiber Length ◽  
Twin Screw Extruder ◽  
Fiber Reinforced ◽  
Screw Extruder ◽  
Nylon 66 ◽  
Glass Fiber Reinforced ◽  
Twin Screw

The fiber brakeage in compounding glass fiber-reinforced nylon-66 with different screw assemblies of the co-rotating twin screw extruder was studied, and comparative analysis of five different screw assemblies was made. The result shows that proper screw assembly could improve the residual fiber length and the mechanical property of the composite effectively

Effect of Wall Conditions on PVC-R Co-Rotating Conical Twin-Screw Extrusion

2011 ◽  
Vol 314-316 ◽  
pp. 419-427
Author(s):  
Ying Han Cao ◽  
Jin Nan Chen
Keyword(s):  
Pressure Difference ◽  
Volumetric Flow Rate ◽  
Wall Slip ◽  
Twin Screw Extruder ◽  
Slip Coefficient ◽  
Twin Screw Extrusion ◽  
Screw Extruder ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Good For

The effect of wall conditions on co-rotating conical twin-screw extrusion of rigid polyvinyl chloride (PVC-R) is studied. The relationship between the shear stress at the screw surface and the slip velocity of the flowing melt obeys Navier’s linear law. When the volumetric flow rate is 3.83×10-5 m3/s, the pressure difference between the entrance and exit of the metering section of co-rotating conical twin-screw extruder is calculated under different wall conditions by using the evolution technique in POLYFLOW. The 3D isothermal flow fields of PVC-R are also calculated. The results show that when the slip coefficient is smaller than 104 , the pressure difference is constant, corresponding to the full slip condition. When the slip coefficient is larger than 104 , with the slip coefficient decreasing, the pressure difference, and the gradients of velocity, pressure and shear rate decrease. The residual stress of the product is thus reduced. Therefore, increasing wall slip is good for the stability of polymer extrusion and the product quality. The dispersive and the distributive mixing of the twin-screw extruder under different slip conditions are also studied. Results show that when the slip coefficient is 107 , it is good for the co-rotating conical twin-screw PVC-R mixing extrusion.

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

2012 ◽  
Vol 468-471 ◽  
pp. 2211-2214 ◽  
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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