Approach to develop a screw configuration for compounding solid fillers on a twin screw extruder using the example of polyethylene-layered silicate masterbatches

Abstract The high potential of layered silicate improving material properties of plastics has been discussed in a significant number of publications. However, homogeneously dispersing it with twin screw extruders is demanding. Available information on optimum screw configuration is contradictory. In this investigation, we develop a practical method for individually designing and optimising extruder sections. This method is applied for designing extruder sections for compounding masterbatches of high-density polyethylene and layered silicate. We found out that for best dispersion, dispersing sections should only be partially filled with melt. Thus, only right-handed kneading elements should be applied.

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Plasticating Single-Screw Extrusion

Rheology and Processing of Polymeric Materials: Volume 2: Polymer Processing ◽

10.1093/oso/9780195187830.003.0007 ◽

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.

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The Comparison of Water Absorption Analysis between Counterrotating and Corotating Twin-Screw Extruders with Different Antioxidants Content in Wood Plastic Composites

Advances in Materials Science and Engineering ◽

10.1155/2011/406284 ◽

2011 ◽

Vol 2011 ◽

pp. 1-4 ◽

Cited By ~ 11

Author(s):

Mohd Hafizuddin Ab Ghani ◽

Sahrim Ahmad

Keyword(s):

Water Absorption ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Wood Plastic Composites ◽

Twin Screw Extruders ◽

Plastic Composites ◽

Study Results ◽

Significant Difference ◽

Twin Screw ◽

Screw Extruders

Water absorption is a major concern for natural fibers as reinforcement in wood plastic composites (WPCs). This paper presents a study on the comparison analysis of water absorption between two types of twin-screw extruders, namely, counterrotating and corotating with presence of variable antioxidants content. Composites of mixed fibres between rice husk and saw dust with recycled high-density polyethylene (rHDPE) were prepared with two different extruder machines, namely, counterrotating and corotating twin screw, respectively. The contents of matrix (30 wt%) and fibres (62 wt%) were mixed with additives (8 wt%) and compounded using compounder before extruded using both of the machines. Samples were immersed in distilled water according to ASTM D 570-98. From the study, results indicated a significant difference among samples extruded by counterrotating and corotating twin-screw extruders. The counterrotating twin-screw extruder gives the smallest value of water absorption compared to corotating twin-screw extruder. This indicates that the types of screw play an important role in water uptake by improving the adhesion between natural fillers and the polymer matrix.

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Non-Isothermal Simulation of Melting Process in Twin Screw Extruder Based on Two Typical Screw Configurations

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.130-134.2273 ◽

2011 ◽

Vol 130-134 ◽

pp. 2273-2279

Author(s):

Chang Liang ◽

Bing Luo ◽

Kui Sheng Wang

Keyword(s):

Liquid Fraction ◽

Melting Process ◽

Melting Zone ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Twin Screw Extruders ◽

Twin Screw ◽

Higher Temperature ◽

Study Heat Transfer ◽

Screw Extruders

In this study, heat transfer and melting process in a co-rotating twin screw extruder are studied based on two typical screw configurations, screw element and kneading blocks staggered 45°. In order to estimate the melting ability of two configurations quantitatively, FEM software, FLUENT is adopted to simulate the cases. It could be concluded that kneading blocks have higher temperature rise and more liquid fraction than screw element, and it takes less time and less distance for kneading blocks to finish melting. Simulation results also show that kneading blocks have more viscous dissipation than screw element. Therefore, we can come to the conclusion that the kneading blocks are more suitable for the melting zone of co-rotating twin screw extruders.

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