Melting in plasticating extuders theory and experiments

Tadmor, Z.; Duvdevani, I.; Klein, Imrich

doi:10.1002/pen.760070313

Cited by 161 publications

(88 citation statements)

References 3 publications

(2 reference statements)

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“…Generally, for thermoplastic materials, in the melting region a melt layer was observed along the barrel and a melt pool close to the active flight. Tadmor et al (1966;1967;1970) extended these studies, and first proposed a mathematical model for melting in a single screw extrusion, and then a composite model of the process. According to this model, traditionally called contiguous solids melting model CSM, a melt layer is formed between the barrel and solid material which is scraped off by the transverse flow in the screw, and a molten polymer accumulates at the active flight where a melt pool is formed.…”

Section: Methodsmentioning

confidence: 97%

Experimental Study for Extrusion of Polypropylene/Wood Flour Composites

Wilczyński

Nastaj

Lewandowski

et al. 2015

International Polymer Processing

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Experimental studies have been carried out for single screw extrusion of PP/wood flour composite of different concentrations of wood flour. A \screw pull-out" technique was used for investigation of the material transport, melting and screw filling. The effect of the screw speed was investigated. It was concluded that WPC extrusion is substantially different from thermoplastics extrusion. Material transport and melting are strongly dependent on the WPC composition, and operating conditions. The contiguous solids melting mechanism CSM is not observed for WPC of high WF content; however, it may be observed for WPC of lower WF content, up to 50 % WF. Several steps of the process are distinguished: material compaction in the solid conveying section close to the active flight and then spreading to the rest of the material, melting which is strongly dependent on the material composition, and shear or plug flow with slipping at the walls in the melt conveying section.

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Section: Methodsmentioning

confidence: 97%

Experimental Study for Extrusion of Polypropylene/Wood Flour Composites

Wilczyński

Nastaj

Lewandowski

et al. 2015

International Polymer Processing

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“…With regard to single-screw extrusion, some experiments have been carried out and various models have been proposed. [1][2][3][4][5][6][7][8][9][10] With respect to twin-screw extrusion, the melting mechanism is not well understood, although some work has been done in the past years. [11][12][13][14][15][16][17][18][19][20] It is well known that, in single-screw extruders, solid polymer is conveyed by the frictional coefficient difference between the surface of barrel and screw, and compacted into a tightly packed solid bed; under the heat transfer from barrels, solid-bedfilm melting mechanism is formed.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of polymer pellets melting mechanisms in corotating twin‐screw extrusion

Zhu¹,

Geng²

2002

Adv Polym Technol

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ABSTRACT:With the visualization corotating twin-screw extruder, the melting of HDPE pellets under different screw configurations and operational conditions was investigated on-line. It is shown that the melting progression of polymer pellets in corotating twin-screw extruders is different from that in single-screw extruders. Screw configuration, screw speed, and feed rate are three decisive factors in polymer melting. Based on the melting phenomena, a new melting mechanism, island-sea melting model, was defined. It was found that island-sea melting model is an important mechanism to realize high efficiency melting progression. The state of polymer, the degree of fill, and the structure of kneading blocks are factors in determining the energy consumption of kneading blocks in melting zone. The conveying of polymer pellets in kneading blocks, in which pellets were compressed and deformed, consumed much more energy than the conveying of polymer melt. This indicates that the control of the deformation of polymer pellets in corotating twin-screw extrusion is a useful concept in developing new screw elements for high efficiency polymer melting.

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“…The model was proven on the basis of published data as well as our own experiments [22,23,31]. When relations between shear stress, shear rate, temperature, and molecular mass and between friction coefficient and temperature were known, the difference between the calculated and experimental values of the melt temperature and its molecular mass at the end of the extruder rarely exceeded 5%, and the difference in pressure was smaller than 30%.…”

Section: Discussionmentioning

confidence: 99%