The Use of Video and the Development of Solids Conveying Theory

Campbell, Gregory A.; Wang, Chicheng; Bullwinkel, M. D.; Nagarajan, Ganesh; Small, J. Douglas; Staples, John L.

doi:10.1016/b978-188420781-5.50029-2

Cited by 4 publications

(6 citation statements)

References 1 publication

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“…The solids are initially transported via Archimedean mechanism, and with increasing flow rate or decreasing screw speed a transition occurs and granules tend to rotate with the screw, and finally solids conveying becomes close to the flood fed extrusion. These conclusions are consistent with the observation of Campbell et al [6] and White et al [36].…”

Section: Discussionsupporting

confidence: 94%

“…The starve‐fed extrusion has several advantages over the flood fed extrusion [2–12]. The pressure built up along the screw is lower than in the case of flood feeding, and therefore there is less chance of agglomeration, and mixing action may be improved.…”

Section: Introductionmentioning

confidence: 99%

“…The studies on starve‐fed single screw extrusion for thermoplastics were mainly focused on mixing and melting capacities [2–12], with little attention to the modeling of the process [5, 7]. Some efforts have generally been done through minor modifications to the equations applied to flood fed extrusion [13, 14].…”

Section: Introductionmentioning

confidence: 99%

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Experimental study for starve‐fed single screw extrusion of thermoplastics

Wilczyński

Lewandowski

2012

Polymer Engineering & Sci

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An experimental study of the polymer behavior in a starve‐fed single screw extrusion is presented. Various polymeric materials, semicrystalline low density polyethylene (LDPE), polypropylene (PP), and (LDPE/PS) polyblends were investigated at various operating conditions. A “screw pulling‐out” technique was used to study polymer behavior along the screw. The solid conveying, melting position, the extent of starvation, and the fully filled regions were observed. Polymer samples were stripped off from the screw which was removed from the machine to investigate melting mechanism. It was seen that filling of the screw channel increases with the flow rate at a fixed screw speed, and decreases with the screw speed at a fixed flow rate. Contiguous solids melting mechanism was observed for flood fed extrusion, but it was not observed for starve‐fed extrusion. A new two‐stage physical model of polymer melting has been proposed with conductive mechanism for melting in the starve‐fed region and dispersed melting mechanism in the fully filled region. Melting action seems to be faster for starve feeding than for flood feeding, since the pellets are not compacted into a dense solid bed. It was observed that the pressure and power consumption considerably decrease with starvation. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

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Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Experimental study for starve‐fed single screw extrusion of thermoplastics

Wilczyński

Lewandowski

2012

Polymer Engineering & Sci

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“…11,31−35 The screw-barrel devices reported in the literature have all been capable of collecting data on the solids conveying machanism such as output rate, pressure, and, in some cases, bed temperature but differed in their function to describe the behavior of these solids in greater detail. Conceptually, these instruments can be categorized as those intending to allow visual observation of the solids Advances in Polymer Technology DOI 10.1002/adv while conveyed 11,32,34 and those providing information on the normal and tangential (shear) stresses experienced by the bed. 31,33,35,36 Arguably, the latter category of use corresponds with its greater strength, allowing the collection of data on the stress state of the bulk down the axial length of the solids conveying zone at differing output and operating conditions.…”

Section: Review Of Testing Apparatusesmentioning

confidence: 99%

“…31,33,35,36 Arguably, the latter category of use corresponds with its greater strength, allowing the collection of data on the stress state of the bulk down the axial length of the solids conveying zone at differing output and operating conditions. Those devices that are made for the visualization of bed movement included a transparent barrel of glass 34 or acrylic, 11 or a metal barrel with quartz windows. 32 In all cases, a top-down perspective of granular motion is offered to researchers by this approach; a viewpoint limited to only the first couple of particle layers next to the barrel wall and that is complicated by the occurrence of dilatancy at the high shear plane.…”

Section: Review Of Testing Apparatusesmentioning

confidence: 99%

Cohesive‐driven particle circulation in the solids conveying zone of a single‐screw extruder

2008

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ABSTRACT:Aspects of heat transfer within the solids conveying zone of a single-screw extruder were studied by using a specially constructed drum testing apparatus. Experiments were conducted with linear low-density polyethylene, polystyrene (PS), and polypropylene (PP) samples by examining their transient temperature profile while the heated drum was stationary or moving. In accordance with classic solids conveying theory, the granular beds of PP and PS remained as plugs while the drum rotated. In such cases, the dominant modes of heat transfer for these systems are conduction through the contact area of a particle and conduction through the interstitial gas. An exception to this behavior was found with PE, in which the bed temperature increased more rapidly while the drum rotated. Visual observations of the bed showed that the particles circulated in the presence of shear and that this complex flow pattern increased in velocity as the drum temperature approached the onset temperature for melting the PE material. With strong correlation between the rate of circulation and the temperature rise in the bed, the movement of particles was assumed to act in a convective heat transfer

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A composite model for starve fed single screw extrusion of thermoplastics

Wilczyński

Nastaj

Lewandowski

2013

Polymer Engineering & Sci

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A composite model has been developed to simulate a starve fed single screw extrusion of thermoplastics. The model is based on combining melt conveying models with new melting models. Illustrative computations are made for low-density polyethylene and polypropylene at various operating conditions. Simulations are made for axial fill factor, pressure, temperature, and melting profiles. The results are validated experimentally. POLYM. ENG. SCI., 54:2362-2374, 2014

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The Use of Video and the Development of Solids Conveying Theory

Cited by 4 publications

References 1 publication

Experimental study for starve‐fed single screw extrusion of thermoplastics

Experimental study for starve‐fed single screw extrusion of thermoplastics

Cohesive‐driven particle circulation in the solids conveying zone of a single‐screw extruder

A composite model for starve fed single screw extrusion of thermoplastics

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