Study of the Charging Zone of a Screw Reactor and the Possibilities of Feeding it with a Polymer Melt

2002 ◽  
Vol 29 (9) ◽  
pp. 55-57
Author(s):  
LM. V. Gachechiladze ◽  
G. T. Oniani
Keyword(s):  
Polymer Melt ◽  
Screw Reactor

Polymer Morphology Revealed by Staining Techniques

1981 ◽  
Vol 39 ◽  
pp. 340-341
Author(s):  
A. C. Reimschuessel ◽  
V. Kramer
Keyword(s):  
Polymer Melt ◽  
Nylon 6 ◽  
Morphological Features ◽  
Negative Staining ◽  
Polymer Morphology ◽  
Crystallizable Polymer ◽  
Staining Techniques ◽  
Long Chain

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.

A Study on Polymer Particle Flow in a Disk Zone of a Screw-Disk Extruder

2014 ◽  
Vol 35 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Tomasz Rydzkowski ◽  
Iwona Michalska-Pożoga
Keyword(s):  
Mechanical Properties ◽  
Computer Simulations ◽  
Particle Motion ◽  
Polymer Melt ◽  
Experimental Tests ◽  
Polymer Particle ◽  
Particle Flow ◽  
Material Particle ◽  
Motion Trajectories ◽  
Stretching Effect

Abstract The paper presents the summary of research on polymer melt particle motion trajectories in a disc zone of a screw-disk extruder. We analysed two models of its structure, different in levels of taken simplifications. The analysis includes computer simulations of material particle flow and results of experimental tests to determine the properties of the resultant extrudate. Analysis of the results shows that the motion of melt in the disk zone of a screw-disk extruder is a superposition of pressure and dragged streams. The observed trajectories of polymer particles and relations of mechanical properties and elongation of the molecular chain proved the presence of a stretching effect on polymer molecular chains.

POLYMER MELT FLOW IN ASYMMETRIC SUDDEN EXPANSIONS: A NUMERICAL STUDY

2016 ◽  
Author(s):  
Felipe Oliveira Basso ◽  
Paulo Zdanski ◽  
Diego Beppler ◽  
Miguel Vaz Jr.
Keyword(s):  
Numerical Study ◽  
Polymer Melt ◽  
Melt Flow

Flow Simulation of a Polymer Melt in a Roller Die

1993 ◽  
Vol 8 (4) ◽  
pp. 328-334
Author(s):  
T. Kegasawa ◽  
J. L. White
Keyword(s):  
Flow Simulation ◽  
Polymer Melt

scholarly journals Modelling of Pore Collapse during Polymer Sintering: Viscoelastic Model with Enclosed Gas

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2182
Author(s):  
Florian Wohlgemuth ◽  
Dirk Lellinger ◽  
Ingo Alig
Keyword(s):  
Surface Tension ◽  
Gas Transport ◽  
Selective Laser Sintering ◽  
Viscoelastic Model ◽  
Polymer Melt ◽  
Gas Diffusion ◽  
Gas Pressure ◽  
Parameter Study ◽  
Time Interval ◽  
Pore Collapse

Frenkel’s model for the late stage of coalescence of viscous particles has been extended to describe pore collapse in a viscoelastic melt during polymer sintering. The shrinkage of a pore in a polymer melt driven by surface tension is extended by taking into account the effects of trapped gas and gas transport out of the pore. Viscoelasticity has been shown to have a considerable impact on the time scale of the coalescence process. In addition, gas diffusion modifies the coalescence dynamics. Based on a parameter study, different regimes for the pore collapse have been identified. At the beginning of pore collapse, surface tension is considerably stronger than gas pressure within the pore. In this time interval (surface-tension-driven regime), the pore shrinks even in the absence of gas diffusion through the matrix. In the absence of gas transport, the shrinkage dynamic slows down and stops when the surface tension balances the gas pressure in the pore. If gas transport out of the pore is possible, surface tension and gas pressure are balanced while the gas pressure slowly decreases (diffusion-controlled regime). The final phase of pore collapse, which occurs when the gas pressure within the pore decreases sufficiently, is controlled again by surface tension. The limitations of the model are discussed. To analyze the interplay between different mechanisms and process steps during selective laser sintering, the respective time scales are compared using experimental data.

scholarly journals Bonding widths of Deposited Polymer Strands in Additive Manufacturing

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 871
Author(s):  
Cheng Luo ◽  
Manjarik Mrinal ◽  
Xiang Wang ◽  
Ye Hong
Keyword(s):  
Polymer Melt ◽  
Acrylonitrile Butadiene Styrene ◽  
High Viscosity ◽  
Numerical Results ◽  
Fused Filament Fabrication ◽  
Cross Sectional ◽  
Nozzle Height ◽  
Special Cases ◽  
Cross Sectional Profile ◽  
Sectional Profile

In this study, we explore the deformation of a polymer extrudate upon the deposition on a build platform, to determine the bonding widths between stacked strands in fused-filament fabrication. The considered polymer melt has an extremely high viscosity, which dominates in its deformation. Mainly considering the viscous effect, we derive analytical expressions of the flat width, compressed depth, bonding width and cross-sectional profile of the filament in four special cases, which have different combinations of extrusion speed, print speed and nozzle height. We further validate the derived relations, using our experimental results on acrylonitrile butadiene styrene (ABS), as well as existing experimental and numerical results on ABS and polylactic acid (PLA). Compared with existing theoretical and numerical results, our derived analytic relations are simple, which need less calculations. They can be used to quickly predict the geometries of the deposited strands, including the bonding widths.

scholarly journals Modeling polymer crystallisation induced by a moving heat sink

Soft Matter ◽  
2021 ◽  
Author(s):  
Sabin Adhikari ◽  
Ahana Purushothaman ◽  
Alejandro A. Krauskopf ◽  
Christopher Durning ◽  
Sanat K. Kumar ◽  
...  
Keyword(s):  
Stefan Problem ◽  
Heat Sink ◽  
Polymer Melt

Recent experiments have shown that polymer crystallisation can be used to “move” and organize nanoparticles. As a first effort at modelling this situation we consider the classical Stefan problem modified for a polymer melt but driven by a heat sink.

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