Single-screw extruder lines give twin-screw performance

Hydrolyzed Kevlar fibers (KFs) were compouded into high-density polyethylene (HDPE) with wood flour (WF) by twin-screw/single-screw extruder to investigate the reinforcement effects of KFs on the mechanical properties of conventional WF/HDPE composites. Maleated HDPE (MAPE) was used as a compatibilizer. The mechanical properties significantly improved as the KFs loading increases in the presence of 4% MAPE, such as tensile strength 14.7%, tensile modulus 12.4%, flexural strength 22.2%, flexural modulus 22.4%, and impact strength 41.7% with 2 wt.% KFs compared to WF/HDPE composite with MAPE. The fiber matrix morphology of the interface region in the composites was examined using scanning electron microscopy (SEM).

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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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Investigation of Mixing Performance in the Extruder with Embedded Planetary-Screws

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.781-784.2809 ◽

2013 ◽

Vol 781-784 ◽

pp. 2809-2816

Author(s):

Liang He ◽

Bai Ping Xu ◽

Hui Wen Yu ◽

Xiao Long Wang ◽

Gang Xue

Keyword(s):

The Novel ◽

Screw Extruder ◽

Mixing Performance ◽

Single Screw ◽

Single Screw Extruder ◽

Laminar Mixing ◽

Single Screw Extruders ◽

Twin Screw ◽

Screw Extruders

The novel geometrical configuration of embedded planetary-screws is proposed in the paper. The corresponding numerical simulation and the experimental investigation are carried out to characterize the mixing performance. Adopting commercial software FLUENT, the simplified physical model is presented with the boundary conditions imposed by UDF codes which are developed by us. Compared with the traditional single screw extruder, the flow and mixing are primarily investigated by using particle tracking technology. The sensitivity to initial positions is found in the novel screw configuration, which is caused by the periodic perturbation of planetary-screws. In contrast, the traditional laminar mixing occurs in single screw extruders. Compared with the traditional twin screw extruder, the experimental characterization of filled system of adding active nanometer CaCO3 into LLDPE matrix is conducted. No obvious difference in dispersion of CaCO3 is found when the extrusion samples are observed through scanning electron microscopy (SEM), on the condition that the both extrusion outputs are equal. The shear rate in the novel screw configuration is relatively smaller, and the extrusion characteristic is more excellent.

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Comparative study on the properties of PVC/TPU blends prepared by single screw and twin screw extruder

Material Science Research India ◽

10.13005/msri/070216 ◽

2010 ◽

Vol 7 (2) ◽

pp. 457-466 ◽

Cited By ~ 1

Author(s):

G. M. Shashidhara ◽

K. G. Pradeepa ◽

Rupalika Goel ◽

R. Bharath ◽

Arun Dhumal Rao ◽

...

Keyword(s):

Weight Ratio ◽

High Hardness ◽

Mechanical And Thermal Properties ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Single Screw ◽

Single Screw Extruder ◽

Variable Weight ◽

Twin Screw ◽

Two Phases

In this work, we have compared the mechanical and thermal properties PVC/TPU blends with variable weight ratio prepared using single screw and twin screw extruder. Two grades of TPUs differing in hardness (Shore A hardness 66 and 85) are used in making the blends. The tensile strength of PVC/TPU-1 and PVC/TPU-2 blends obtained from twin screw extruder is higher by 39% - 98% and 89% - 143% than that obtained from single screw extruder, which indicates intimate mixing of two phases in twin screw extruder. Beyond 30 % of TPU content, the blends of TPU-2 (high hardness grade) exhibit relatively high modulus compared to blends of TPU-1. The blends prepared by twin screw extruder were relatively harder. The rebound resilience of blends prepared by twin screw extruder was found to be always more. The rebound resilience of PVC/TPU-1 blends is relatively more compared to PVC/TPU-2 blends due to more number of soft segments in TPU-1. The blends were also characterized by abrasion resistance, MFI, DSC and TEM.

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Effect of Flow Field on Online Shear Viscosity of PP/nano-CaCO3 Composites

Fluids Engineering ◽

10.1115/imece2006-15808 ◽

2006 ◽

Author(s):

Guo Jiang ◽

Hanxiong Huang

Keyword(s):

Shear Viscosity ◽

Chaotic Mixing ◽

Twin Screw Extruder ◽

Screw Extruder ◽

Rheological Analysis ◽

Single Screw ◽

Single Screw Extruder ◽

Mixing Intensity ◽

Twin Screw ◽

High Shearing

Polymer nanocomposites have been regarded as a new category of engineering materials and attracted technical and scientific interest. Recently rheological analysis became an effective tool for investigating the microstructures of nanocomposites. However, the online rheological property of nanocomposites during compounding was seldom studied. In this work, two types of screw configurations in twin-screw extruder were selected, one provides high shearing intensity and the other provides high shearing/mixing intensity. In addition, chaotic mixing was induced by installing a single screw extruder with a convective screw at the end of the twin-screw extruder to compound the nanocomposites. The online melt shear viscosity of nanocomposite was measured using Haake ProFlow online rheometer. Effects of high shearing, high shearing/mixing, and chaotic mixing on the online shear viscosity for polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composites were investigated. The study showed that the chaotic mixing facilitates the processing of the nanocomposite.

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Mechanical Properties of Rubber Scrap – Polyolefine Compositions

Progress in Rubber Plastics and Recycling Technology ◽

10.1177/147776060201800303 ◽

2002 ◽

Vol 18 (3) ◽

pp. 173-193

Author(s):

Ewa Kowalska

Keyword(s):

Mechanical Properties ◽

Maximum Amount ◽

Twin Screw Extruder ◽

Mechanism Of Formation ◽

Screw Extruder ◽

Single Screw ◽

Single Screw Extruder ◽

Twin Screw

The mechanical properties and the structure of sections of specimens prepared from rubber scrap – polyolefin compositions were investigated. The comminuted vulcanised rubber scrap rubber scrap was used in an amount of 5 – 75 wt%. The mode of incorporation and the method of preparation of the composition in a single-screw or a twin screw extruder, was examined. The maximum amount of the rubber scrap that can be added to compositions prepared by single screw extruder and a twin screw extruder was found to be up to 75 wt% and up to 30 wt% and for both polyolefins, respectively. Silanes were studied as additives intended to compatibilize thermoplastics and rubber scrap. The mode of incorporation of silanes and the method of preparation of the composition were examined. The mechanism of formation of rubber scrap – polyolefin compositions was defined.

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Determination of the phase structure of polymerblends by electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109604 ◽

1978 ◽

Vol 36 (1) ◽

pp. 492-493

Author(s):

Dr. G. Kaemof

Keyword(s):

Screw Extruder ◽

Electron Microscopic ◽

Thin Sections ◽

Single Screw Extruder ◽

Transmission Electron ◽

The Matrix ◽

Twin Screw ◽

Special Case ◽

Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

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