Melting of Plastics in Kneading Blocks

Todd, David B.

doi:10.3139/217.930113

Cited by 36 publications

(19 citation statements)

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“…They suggest both pressurized flow and material conveying in the intermeshing region. The problem of melting in co-rotating twin screw extruders has received little treatment, indeed only Todd [11] has made a major contribution. Some results are in a paper by Kim and White [12].…”

Section: Introductionmentioning

confidence: 99%

Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder

Bawiskar¹,

White²

1995

International Polymer Processing

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A flow visualization study of starve fed solids conveying in single screw and a modular self-wiping co-rotating twin screw extruder is observed inflow visualization experiments. Single screw extruders exhibit forward Archimedean transport of material on the undersides of the screw. Self-wiping co-rotating twin screw extruders conveying forward in the intermeshing region and in the region near the apex between the screws. Observations are reported of the melting of solid pellets and possible melting mechanisms are discussed.

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Section: Introductionmentioning

confidence: 99%

Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder

Bawiskar¹,

White²

1995

International Polymer Processing

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“…The barrel heat melting process is likely to be influenced by factors such as uniform product temperature, poor thermal conductivity of the polymers, and volumetric scale-up. About 80-90 % of melting is achieved by viscous dissipation via frictional forces (including interparticle, material/wall, and material/screw friction) (Tadmor and Klein 1970;Todd 1993). The mechanical energy is mainly dissipated in three different ways: frictional energy dissipation (FED) from the frictional movement of polymer solid particles, plastic energy dissipation (PED) from the irreversible deformation of solid particulates, and viscous energy dissipation (VED) from the irreversible deformation, i.e., flow of the polymer melt.…”

Section: Melting and Mixingmentioning

confidence: 99%

Melt Extrusion in Drug Delivery: Three Decades of Progress

Shah

Repka

2013

AAPS Advances in the Pharmaceutical Sciences Series

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This chapter appraises the role of melt extrusion as a solubilization and bioavailability enhancement technique. The introductory chapter highlights major aspects of hot melt extrusion (HME) technology as applied in the pharmaceutical industry, particularly processing techniques, material considerations, recent innovative applications of melt extrusion in drug delivery system design, and a review of current HME-based formulations (marketed or under commercial development). The chapter also focuses on key development aspects of HME processes, such as material sparing screening approaches, process formulation relationships, and stability evaluation of prototype formulations, which emphasize the clinical and biological significance of this technique. In addition, it displays the journey and evolution of this important processing technology into an established pharmaceutical manufacturing platform. The chapter describes several case studies wherein melt extrusion has been utilized to develop commercial drug products.Early-stage development in melt extrusion encompasses various critically interdependent areas involving process considerations, stability assessment of prototype formulations, and performance evaluation (with respect to intended applications) of prototype formulations. Processing ConsiderationsProcessing considerations is a rather broad terminology covering material properties, instrument considerations, and process-formulation interplay. Systematic research over the last couple of decades has revealed that critical product quality attributes are directly dependent on both "formulation" and the "process" employed. It is important to note that the interplay between these determines the finished product attributes. Material PropertiesAll of the materials used in melt extrusion (drugs, carriers, processing aids, release modifiers, etc.) should meet certain minimal pharmaceutical criteria, which

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“…Here, the individual operations taking place during the plasticization process are depicted by analogy to the plasticization process in singlescrew extruders. The chief operations involved are the following More recent investigations are presented by Todd in [3]. The use of a screw barrel which folds open in the longitudinal plane made it possible to establish the chief melting mechanisms for powder and pellets.…”

Section: State Of the Artmentioning

confidence: 98%

Theoretical and Experimental Investigations of the Melting of Pellets in Co-Rotating Twin-Screw Extruders

Potente

Melisch

1996

International Polymer Processing

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Knowledge of the plasticizing behavior in tightly intermeshing, co-rotating twin-screw extruders is of crucial importance for assessing the compounding process. Experiments were conducted on a laboratory extruder in order to establish the parameters that influence the melting process. Solidified samples of material were taken from the screw and microtome cuts produced from the plasticizing section. These were then assessed on the basis of image analysis. This visualization of the solid and molten phases which are present simultaneously together with the distribution of the two phases made it possible to quantify the reduction that occurs in the amount of solid material over the length of the screw configuration employed.A model is additionally presented for the calculation of the melting lengths and the melting profiles. This works on the basis of individual particles which are uniformly dispersed in the polymer melt. Allowance is made for the temperature increase in the solid material conveying section. A comparison of calculated and experimentally determined melting lengths revealed a satisfactory level of agreement.International Polymer Processing downloaded from www.hanser-elibrary.com by Kungliga Tekniska on August 20, 2015For personal use only.

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Melting of Plastics in Kneading Blocks

Cited by 36 publications

References 0 publications

Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder

Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder

Melt Extrusion in Drug Delivery: Three Decades of Progress

Theoretical and Experimental Investigations of the Melting of Pellets in Co-Rotating Twin-Screw Extruders

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