bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Agglomerate Rupture in Linear Flow Fields
Authors: Manas-Zloczower I. , Feke D. L. 
Published: December 2013

Abstract
A dispersive mixing model focusing on the rupture of agglomerates as the step that primarily determines the dynamics of the mixing process was developed and analyzed. Rupture is predicted to occur when hydrodynamic forces exerted on the outer surface of the agglomerate exceed cohesive forces binding the agglomerate together. Agglomerates are modeled as clusters of aggregates bound by van der Waals forces. The magnitude and orientation of the rupturing hydrondynamic force depend on the local stress field in the fluid. Cleavage of the agglomerate is predicted to occur at the mid-plane of the agglomerate where the effects of hydrodynamic tension is the largest. Under the assumption that parent agglomerates and their fragments have the same shape, the kinetics of the rupture process is found to be independent of the absolute size of the agglomerate. Following from this is the result that the dispersion process is governed by flow dynamics, i.e., a minimum value of flow strength, which depends on the geometry of the bulk flow field, is required for rupture of the agglomerate. Agglomerate rupture was investigated in four flow geometries: simple shear; pure elongation; uniaxial extension, and biaxial extension. The efficiency of each flow geometry is compared on the basis of power and time requirements to achieve a given degree of dispersion.
Flow Visualization of the Rubber Compounding Cycle in an Internal Mixer based on Elastomer Blends
Authors: Morikawa A. , Min K. , White J. L. 
Published: December 2013

Abstract
A flow visualization study of the blending of elastomers and the subsequent mixing of carbon black and oil in an internal mixer is described. The elastomers studied were natural rubber, cis-polybutadiene and a solution styrene-butadiene copolymer. Studies were made of addition to the mixer of mini bales of earch rubber pigmented with different colors and their subsequent homogenization. Subsequently we investigated the blending of bales of the different rubbers and determined the homogenication times. Similar investigations were made of the addition of carbon black and oil black homogenization times and oil absorption times were determine. These are correlated with the rheological properties of the elastomers.
Use of Chilled Die Lips to Improve Production Rates in Extrusion of PE
Authors: Cook D. G. , Cooke R. , Rudin A. 
Published: December 2013

Abstract
Extrusion rates of polyethylene are limited by the onset of surface defects in the extrudates, which are variously termed sharkskin, melt fracture and so on. Several expedients are effective in relieving this problem. We report here that extrudate surface distortion can be eliminated under some conditions by cooling the die, at normal melt extrusion temperatures. This technique appears to be generally effective for LLDPE and HDPE. The process has been patented [10] for polymers with narrow molecular weight distributions.
Characterization of the Sharkskin Defect and its Development with the Flow Conditions**
Authors: Beaufils P. , Vergnes B. , Agassant J. F. 
Published: December 2013

Abstract
We have studied the development of the sharkskin defect of a linear low density polyethylene, by using complementary experimental techniques. Roughness measurements have allowed to accurately characterize the surface of the extrudates. Flow birefringence observations have permitted to visualize the flow conditions inside the die. The development of the defect is strongly dependent on the temperature and quasi-independent on the geometry (die length, entry angle). Theoretical computations of the flow through the slit die have allowed the correlation of the amplitude of the defect with the stress distribution. Sharkskin defect appears as a continuous and regular phenomenon of surface degradation without intervention of wall slip.
Reactive Ion Etching of Polymer Films
Authors: Dems B. C. , Rodriguez F. , Solbrig C. M. , Namaste Y.M.N. , Obendorf S. K. 
Published: December 2013

Abstract
The need for nanometer-sized features in integrated circuits calls for the use of dry-etching techniques using glow-discharge plasmas. The reactive ion etching (RIE) mode in which there is a large difference in potential between the gas phase and the solid surface yields particularly desirable, straight-walled etched structures. The design of processes and materials for RIE requires a knowledge of the effects of operating variables on various parameters. In the present work, the parameter emphasized is the etch rate. A novel aspect of the apparatus used incorporates a laser interferometer for in situ measurements of etch rate. Some observations on operating variables are: i. Chamber pressure is more critical when a fluoride-oxygen plasma is used than when oxygen alone is used. This is due to polymer deposition that occurs with the former along with etching. 2. The etch rate in the oxygen/RIE mode is almost the arithmetic sum of the oxygen/plasma mode together with the nitrogen/RIE mode except at low incident power levels where etch rate with oxygen/RIE is much greater than the sum of the other two. 3. Aromatic polymers etch more slowly than aliphatic polymers. 4. The oxygen/RIE rate of polyvinylchloride, PVC, decreases on addition of a compatible organotin compound. A 1:1 mixture of PVC with a tin compound etches at i/10 the rate of PVC alone.
New Aspects in the Design of Extruders with a Forced Feeding Section
Authors: Potente H. , Koch M. 
Published: December 2013

Abstract
New aspects in the design of forced feed section extruder (FFSE) screws are presented which are based on the understanding of the pressure profiles along the screw. The pressure at the end of the grooves correlates with the throughput characteristics in so far that when the maximum build up of pressure in the solid is exceeded, a kink in the throughput curves occurs due to high energy dissipation. This leads to partial melt film friction in the groove section. This can be avoided by the consequences shown in the paper for the design based on a reduced pressure consumption in the zones subsequent to the feeding zone. All criteria are dealt with analytically so to calculate and predetermine the process behaviour as a function of screw geometry. By the way, the main disadvantages of the FFSE can be kept under control as this new understanding is consequently applied to process as well as to screw design. The results of the process analysis are prooven by experimental work.
Continuous Melt Polymerization of Polyetherimides
Authors: Schmidt L. R. , Lovgren E. M. , Meissner P. G. 
Published: December 2013

Abstract
A new process for continuous melt polymerization of aromatic dianhydrides and diamines has been developed. The process consists of several integrated stages: feeding, melting, devolatilization, mixing, and advanced polymerization. The transport phenomena and coupled reaction rates have been studied in a corotating, intermeshing twin-screw reactor/extruder. Each stage in this process has been analyzed. The results show the importance of viscous heat for melting monomers, free surface generation in mass transfer, total shear strain in distributive mixing, and back mixing for extended residence time and advanced polymerization. High molecular weight polyetherimide (Mw 50 × 103) was obtained with this process for a variety of conditions. The reactions were run with 3 mole % of monofunctional anhydride to cap the polymer ends at a specific molecular weight for the most desirable balance of mechanical and physical properties.
Effect of Spinline Quenching on Structure Development in High-speed Melt Spinning of PET
Authors: Kikutani T. , Morinaga H. , Takaku A. , Shimizu J. 
Published: December 2013

Abstract
In the high speed melt spinning of polyfethylene terephthalate), the spinline was quenched with a water-bath and diameter profiles were measured. The filament diameter measured just above the water-surface was much thicker than that of the asspun filament and the deformation of filament after it was immersed in the water was suggested. At a take-up velocity of 6000 m/min without a water-bath, neck-like deformation was observed. When the water-bath was set farther from the spinneret than the position of neck-like deformation, the diameter at the water-surface was still thicker than that of as-spun filament. In other words, neck-like deformations disappeared. The friction stress applied to running filament by the water was estimated from the measurement of spinline tension. The calculation of the temperature distribution in the filament cross-section revealed that cooling behavior in the water is governed not by heat transfer from a filament surface to the water but by heat conduction in the polymer. Rapid increase of spinline tension due to high friction stress by the water and relatively slow cooling of filament due to low heat conductivity of the polymer lead to the deformation of filaments in the water and disappearance of neck-like deformation.
Compression Mold Filling Simulation for Non-Planar Parts
Authors: Osswald T. A. , Tucker C. L. 
Published: December 2013

Abstract
We describe a simulation of compression mold filling that combines a Galerkin finite element solution of the governing equations with a control volume scheme for tracking the moving flow front. The method can model thin shell-like parts in three dimensions, single or multiple charges, and multiply-connected domains. Either the generalized Hele-Shaw formulation or the thin-charge limit of Barone and Caulk's model can be used for the governing equations. The numerical techniques are explained, with special attention to the recovery of approximate flow front shapes. Predictions compare favorably to experiments, including laboratory experiments on model fluids as well as two large commercial parts molded from sheet molding compound. The simulation is most accurate when the initial charge thickness in uniform, but can also model multi-thickness charges.
Thermoforming of Amorphous PET Sheet
Authors: Birley A. W. , Haworth B. , Ola A. O. 
Published: December 2013

Abstract
A novel practical approach has been used to study the processability of a commercial grade of poly(ethylene terephthalate) during vacuum forming, in order to derive statistical models to relate some physical properties of containers to the thermomechanical nature of the process. Two-variable and three-variable Factorial Experimental designs were chosen to model the practical vacuum forming, and plug-assisted forming techniques, for process draw ratios of 1:1 and 2:1. Response measurements included container thickness distribution, and high temperature dimensional stability. Coefficients for a simple polynomial model have been experimentally determined: statistical correlations were apparent throughout the study, showing that the process environment determined the properties of vacuum formed containers through the morphological changes which occur by deforming in the thermoelastic region. Thickness distribution is improved when the plug assist mode is utilised. However, further optimisation is apparent when stress-induced crystallisation in PET is promoted (for example, when forming at a relatively low sheet temperature), especially for deep-drawn containers deformed beyond the natural draw regime. Whilst the temperature of the PET sheet primarily determines component thickness distribution, high-temperature stability is promoted by increases in the degree of crystallinity which occur when vacuum forming using super-ambient molding tool and plug temperatures.
Effect of Various Parameters on Residual Stresses in Transparent Polymeric Tubes
Authors: Mittal R. K. , Khan I. A. 
Published: December 2013

Abstract
Using the photoelastic technique for the measurement of residual stresses in rods and tubes of transparent polymers, the effect of some processing parameters such as the initial and final temperatures of quenching, type of cooling medium and the tube wall thickness is examined. These parameters have been shown to influence the magnitude and distribution of residual stresses. Also, a simplified version of the technique has been suggested to assess the magnitude of stresses in such tubes during fabrication itself. This simplified version yields necessary information about the stresses within an accuracy of approximately ± 10%.
Modified Flow Analysis Network Method for Analysis of Extrusion and Molding
Authors: Brzoskowski R. , Kumazawa T. , White J. L. 
Published: December 2013

Abstract
An improved form of the numerical FAN method of Tadmor, Broyer, and Gutfinger for solving hydrodynamic lubrication theory problems in flow through molds and dies has been developed. The new procedure takes into consideration transverse shearing in two rather than only one direction. It is also applied to the class of problems considered by Szydlowski, Brzoskowski, and White which involved applying this technique to situations when one surface is stationary and the other moves, such as in screw sections of extruders.
Throughput characteristics of Tightly Intermeshing Co-rotating Twin Screw Extruders
Authors: Potente H. , Ansahl J. , Wittemeier R. 
Published: December 2013

Abstract
This paper presents a mathematical-physical model for tightly intermeshing co-rotating twin screw extruders which describes the throughput and pressure characteristics of these extruders in the sections filled with molten plastic. With the equations that have been compiled, it is possible to calculate pressure profiles and back-pressure lengths for individual sections of isothermal and two-dimensional flow with non-Newtonian melts, making allowance for the screw geometry and for the parameters of relevance to the process. A comparison of the results supplied by the formulated theory and those obtained from the experiment shows that good computed results are obtained for various materials and different points of operation, although no allowance is made for the leakage flow that occurs in reality.
A 3D Mold Filling Study with Significant Heat Effects
Authors: Tanguy P. A. , Lacroix R. 
Published: December 2013

Abstract
A three dimensional finite element methodology is presented for the modelling of complex injection mold filling, using an extension of the Flow Analysis Network method coupled to a three dimensional solution of the thermal equations with phase change. The method allows the computation of the propagation of the polymer melt front with time as well as the prediction of the frozen skin which occurs during filling. Illustrations are presented in the context of an industrial mold, and simulation results are validated against experimental data showing a reasonable agreement.
Plastics Magnet Manufacturing Process: Mixing, Kneading, and Injection Molding
Authors: Sakai T. , Nakamura K. , Morii A. 
Published: December 2013

Abstract
To manufacture anisotropic plastic magnets with higher magnetic power, the compounding of Strontium Ferrite powder / plastics binder and injection molding processes should be optimized. In this study, we have carried out the optimization of injection molding machine design, and the mechanism analysis of the compounding operation. As a result, to generate effective strong magnetic fields during injection molding, the coiling system, mold structure, and pole shape were very important elements. Better Ferrite powder dispersion accelerated the particle orientation, which lead to higher magnetic power of the molded product when strong magnetic fields were applied. And then, particle dispersion depended on specific energy of the compounding machine unless excessive shearing force degraded Ferrite and plastics binder.
Prediction of Optimum Process Conditions for Rotomolded Products
Authors: Crawford R. J. , Nugent P. , Xin W. 
Published: December 2013

Abstract
This paper describes analytical and experimental work which has been carried out to identify optimum process conditions for rotomolded products. The mechanical performance of the moldings has been assessed using tensile impact tests. It has been found that changes in the oven temperature or oven time cause a very significant shift in the ductile-brittle transition for the SCLAIR 8504 grade of polyethylene used in the work. Optimum combinations of process variables can be clearly defined and used to establish a processing window for the material.
The ROTOSIM computer simulation for the rotomolding process has been used to establish the best (most economic) combinations of process conditions to obtain the optimum mechanical properties. A single equation is presented to relate pool depletion time to some of the process variables.
Observation and Analysis of Carbon Black Agglomerate Dispersion in Simple Shear Flows
Authors: Rwei S.-P. , Horwatt S. W. , Manas-Zloczower I. , Feke D. L. 
Published: December 2013

Abstract
Experiments aimed at detecting agglomerate dispersion were performed in a rotating concentric cylinder device mounted in a light scattering monophotometer. The dispersion of carbon black agglomerates suspended in various media (e.g. water, squalene, poly (dimethyl siloxane)) was inferred by measuring changes in turbidity under the application of a controlled simple shear field. In a given suspension the turbidity was observed to be constant for shear rates less than a threshold value. At shear rates in excess of this value, the turbidity was observed to increase monotonically in time to a steady state value. The effects of particle size and fluid viscosity on the critical shear rate necessary to induce agglomerate breakage were examined. Also, the change in the nature of the agglomerate size distribution upon shearing was studied. The results obtained indicate that the breakup of highly structured agglomerated solids such as carbon black does not proceed by a halving process. Also, the initial breakup process was observed to be irreversible.
A Model of Flow in the Mixing Section of the List KoKneader
Authors: Brzoskowski R. , Kumazawa T. , White J. L. 
Published: December 2013

Abstract
In this paper, an analysis for a whole section of the List KoKneader is presented. The analysis is restricted to the isothermal flow of a Newtonian fluid and uses a modified Flow Analysis Network method of simulation. This paper continues our efforts to analyze the flow of polymer melts in screw extruders containing pins.
Drag and Pressure Flow in Twin Screw Extruders
Authors: Todd D. B. 
Published: December 2013

Abstract
Staggered arrays of kneading paddles in co-rotating intermeshing twin screw extruders have drag and pressure characteristics similar to those in conventional screws. The pressure flow term was determined by measuring pressure drop as a function of flow rate in a non-rotating configuration. The drag flow per revolution was estimated as half of the product of lead length and open barrel cross section. The preliminary determinations were subsequently confirmed in a flooded operating extruder.
Fluid Mechanics of Distributive Mixing in a Modular Intermeshing Corotating Twin Screw Extruder
Authors: Monies S. , White J. L. 
Published: December 2013

Abstract
A theory of distributive mixing in a modular intermeshing corotating twin screw extruder is described. This is based on the Spencer – Wiley premise of representing mixing through interfacial area increase and its relationship to shear strain. The increase of interfacial area in both screw elements and kneading disc elements is analyzed. The flow in screw elements has a figure eight configuration but basically is analogous to flow in a single screw extruder. The primary mixing mode in these machines is within the kneading disc elements. A model for increase of interfacial area, which includes backflows through kneading disc tips, is developed. The kneading disc and screw element models are combined to compute interfacial area development in modular twin screw machine. We consider that modular twin screw extruders often have regions of starvation. To apply this model it is necessary to know flow configurations such as may be determined by a composite model of the total flow such as has been developed by the authors and their coworkers in earlier papers.
A Fundamental Experimental Study of the Mechanisms of Warpage and Shrinkage of Polyethylene in Rotational Molding
Authors: Chen C. H. , White J. L. , Ohta Y. 
Published: December 2013

Abstract
An off-line experimental simulation of cooling and warpage of rotationally molded parts is described. Slabs of polyethylene rotationally molded parts containing thermocouples and monitored by displacement transducers are placed on a metal surface representing a mold wall. This is cooled by varying methods such as simulated water showers, fan blown air, and natural convection cooling. Temperature profiles in the mold wall and through the polymer are determined as a function of time. The position of crystallization and the development of warpage are observed. Warpage is attributed to thermal quench stresses and release of the polymer from the mold surface.
Production and Characterization of Fine-dispersed Mixtures of Liquid Crystalline with Conventional Polymers
Authors: Meretz S. , Kwiatkowski M. , Hinrichsen G. 
Published: December 2013

Abstract
By investigation of adhesion following the harmonic mean method after Wu a suitable pair out of seven liquid crystalline (LCP) and conventional polymers was established in order to produce a LCP-matrix compound. Using a bidirectional piston mixer with a steel wire mesh with mesh size of 63 μm, 5% of the picked out PHB-PET copolymer was finely dispersed into the PET matrix polymer in the molten state. As a result a dispersion of the initial volume of the LCP granules of 1 mm3 into small particles of 0.5 to 1.0 μm3 as well as a very uniform local distribution was achieved which can be considered as an argument for the compatibility of the selected pair and as a confirmation of the usefulness of the preceding investigations of adhesion.
Dimensionless Non-Newtonian Isothermal Simulation and Scale-up Considerations for Modular Intermeshing Corotating Twin Screw Extruders
Authors: Chen Z. , White J. L. 
Published: December 2013

Abstract
Dimensionless calculations for throughput and pressure gradients are reported for flow of non-Newtonian fluids in screw and kneading disk elements of a modular intermeshing self-wiping corotating twin screw extruder. These calculations are applied to compute pressure and fill factor profiles along the axis of commercial twin screw extruders of varying scale. The used twin screw geometries are found to allow scaling for both the double threaded/tipped and triple threaded/tipped screw/kneading disc families. Dimensionless calculations are presented and applications to modular machines design are described.