bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow Visualization Parallel and Perpendicular to the Rotor Axes for Elastomers and Molten Plastics in an Internal Mixer
Authors: Min K. 
Published: December 2013

Abstract
Basic studies of flow visualization for elastomers and plastics in an internal mixer are described. A modified laboratory mixer with transparent front and trasverse windows was used to observe parallel and perpendicular motions. Shearing, stretching and tearing motions were observed especially for elastomers. Various rotor designs were used. These indicate different flow fields along the rotor axes, and the interchange of materials between rotors. We describe the different flow fields observed for elastomers and plastics creasted by various rotor designs.
Recent Studies on Degradation Mechanism of Rubber Vulcanizates by Chemorheology
Authors: Murakami K. 
Published: December 2013

Abstract
A critical discussion is presented of the influence of chemical degradation mechanisms on the mechanical properties, especially stress relaxation, of vulcanized rubber. The response of the vulcanizate is interpreted in terms of the kinetic theory of rubber elasticity. Different chemical mechanisms are explored. The influence of diluent is interpreted in terms of the kinetic theory of rubber elasticity. Different chemical mechanisms are explored. The influence of diluent is considered. Comparisons are made to experiments on polyisoprenes and polyurethanes.
On Dispersed Crystallization in Polymer Melts as Proceeding from a Quenched Boundary
Authors: Janeschitz-Kriegl H. , Krobath G. 
Published: December 2013

Abstract
The present paper is concerned with a crystallization process which occurs in the interior of a polymer melt, when its boundary (mold wall etc.) is suddenly quenched. As polymer melts are prone to supercooling, dispersed nucleation can take place at a distance from the boundary, if the local temperature has become low enough. This results in (delayed) formation of a crystallization zone moving into the bulk of the material. An approximate methematical treatment of this phenomenon enables an easy (semi-quantitative) interpretation of experimental results which were obtained with the aid of a technique of visual inspection on a high density polyethylene (HDPE) sample.
Simulation of Flow and Mixing in an Internal Mixer
Authors: Kim J. K. , White J. L. , Min K. , Szydlowski W. 
Published: December 2013

Abstract
A mathematical model is developed for simulation of flow in an internal mixer with two counter rotating non-intermeshing rotors is presented. The model presumes rotors with a screw flight which is separated into two sections. The mixing chamber is taken to be fully filled and rotor curvature neglected in analogy to screw extruder analyses. Lubrication theory is used and the fluid presumed Newtonian. The flow patterns within the mixing chamber are computed. The conditions under which rotor designs lead to global circulation patterns within the mixing chamber and good distributive mixing are considered. We also investigated the extent of fluid motion over rotor tips which should lead to dispersive mixing.
Gelation and Fusion of PVC Plastisols with Plasticizers of Varying Solvent Power
Authors: Nakajima N. , Sadeghi M. R. 
Published: December 2013

Abstract
During gelation and fusion process PVC plastisols changes from a suspension of resin particles in a liquid plasticizer to a uniform mass. The manner of change was observed with a scanning electron microscope, SEM. Four different plasticizers varying solvent power were used: they were dioctyl phthalate, dioctyl sebacate, dibutyl sebacate and tricresyl phosphate. Significant differences were observed among different plasticizer systems in a manner of dissolution of PVC into a plasticizer, swelling of PVC particles with a plasticizer and fusing to form a uniform mass. The SEM micrographs are presented with reference to the viscoelastic properties at the corresponding temperature.
Thermal Aging on the Dielectric Properties of Recycled High Impact Polystyrene
Authors: Salman S. R. , Al-Jarrah M. F. , Hammo S. A. 
Published: December 2013

Abstract
The dissipation factor and dielectric constant of thermally aged recycled high impact polystyrene (HIPS) were measured at different aging temperatures. The results indicates that the degradation of HIPS is mainly due to surface action with minor chemical change.
Structure Development in the Melt Spinning and Drawing of Poly p Phenylene Sulfide Fibers
Authors: Song S. S. , White J. L. , Cakmak M. 
Published: December 2013

Abstract
The development of crystallinity and orientation in melt spun and subsequently drawn poly p phenylene sulfide (PPS) fibers is investigated using differential scanning calorimetry (DSC), birefringence and wide angle x-ray diffraction (WAXS) techniques. The melt spun PPS fibers were found to possess small amounts of crystallinity at moderate draw-down ratios. The fibers may be crystallized to a significant extent by subsequent drawing over a hot plate. The levels of crystallinity and orientation in the largely glassy melt spun PPS fibers has been determined as well as subsequently drawn fibers. Uniaxial mechanical properties were determined as a function of spinning and drawing conditions. In general, elongation to break decreases while modulus and tensile strength increase with an increase of melt spinning draw down ratio and solid draw ratio. The Young's modulus and tensile strengths are increasing functions of fiber birefringence and the elongation to break a decreasing function.
Air Ring Effect on Blown Film Dynamics
Authors: Cao B. , Campbell G. A. 
Published: December 2013

Abstract
The air ring has an effect on blown film dynamics. By using a momentum macrobalance, an analytical solution for the pressure on the outer surface of the bubble is obtained which is in fairly good agreement with our aerodynamic experimental data. Since the pressure is related to the hoop stress, a more complete prediction of the bubble shape is attained by taking the air ring effect into account.
Advances in Rheological Analysis of Injection Molding
Authors: Bernhardt E. C. , Bertacchi G. , Moroni A. 
Published: December 2013

Abstract
Finite element methods offer the potential to greatly refine mold filling analysis. As a consequence, there is strong pressure to apply this technology on a routine basis in industry. Unfortunately, traditional finite element techniques are not adequate to design a viable model of the flow of molten plastic into a mold. This paper explains the mathematical problems that must be solved. It describes why the widely used classical matrix techniques give erratic results, and demonstrates that it is mandatory to apply a total dynamic analysis to obtain a reliable mold filling simulation. A new technique is introduced to solve the problems caused by non-linear material properties and moving boundaries.
Position of Neutral Surface during Hollow Disk Compression Molding of Long Fibre-Reinforced Thermoplastics**
Authors: Hojo H. , Kim E. G. , Onodera T. , Yaguchi H. , Kim S. H. , Koshimoto M. 
Published: December 2013

Abstract
A model is presented which can be used to explain the friction condition on the interface between the composites and the mold during sheet-like parts compression molding of fibre-reinforced thermoplastics. The composites is treated as an incompressible isotropic fluid. Circular hollow disk is compressed in order to derive the position of the neutral surface which can explain the interfacial friction from consideration of minimum energy dissipation. From the theory and the experiment, it is clear that there is slip on the mold surface. By using the nondimensional parameter which measures the ratio ofvicous to frictional resistance, the phenomenon of the friction can be well explained.
A Model for Single-screw Plasticating Extruders
Authors: Vincelette A. R. , Guerrero C. S. , Carreau P. J. , Lafleur P. G. 
Published: December 2013

Abstract
A mathematical model has been developed to describe the steady-state behavior of single-screw plasticating extruders. The model is capable of predicting the solid bed profile, pressure, and polymer temperature profiles along the screw channel. The model is based on concepts developed by Tadmor and Klein [1], but a modified model for plastication rate is proposed and the pressure profile is calculated using a unidirectional power-law flow model, in which correction factors for flight walls, curvature, and varying channel height have been incorporated. A finite difference technique (Crank-Nichols on method) is used to compute the polymer temperature profile. The overall extruder performance (pressure, temperature and solid bed profiles) is obtained with short computer times on a personal computer (typically one minute on IBM AT). A series of menus and graphics allow for selective simulation and rapid visualization of effects of key parameters, making the model attractive for screw design and optimization of operating conditions. The predictions are in good agreement with experimental data obtained for a polyethylene on a 45 mm diameter screw extruder.
Flow in a Modular Intermeshing Co-rotating Twin Screw Extruder
Authors: Wang Y. , White J. L. , Szydlowski W. 
Published: December 2013

Abstract
The flow of viscous power law fluids in the various modules of a modular intermeshing co-rotating twin screw extruder. This includes right-handed and left-handed screw elements and kneading disc assemblies with various staggering angles. The calculations are based on hydrodynamic lubrication theory used a new calculation method based on combining methods by Tadmor, Broyer and Gutfinger, and by Griffith. The behavior of a composite twin screw extruder consisting of assemblies of screw and kneading disc elements is investigated and the potential of having a sequence of fully filled and starved regions is considered. The existence of such distribution of polymer and starvation behavior in a twin screw machine was found in experiments with a polyethylene. The material distribution is reasonably well predicted by the non-Newtonian flow model of this paper.
Incremental Drawing of Polyethylene-terephthalate Partially Oriented Yarn (PET-POY)**
Authors: Mukhopadhyay A. K. , Misra A. , Dutta B. 
Published: December 2013

Abstract
Polyethylene terephthalate (PET) is generally melt spun to give yarns which are then drawn at an elevated temperature since the glass transition (Tg) of PET is 70 °C. Incremental drawing of synthetic fibers involves the drawing of as-spun yarns in several discrete steps along the surface of two corotating conical bodies. For drawing at an elevated temperature a chamber type of heating system was designed in which the drawing bodies were enclosed and a constant temperature maintained. Multifilament PET-POY (Polyethylene Terephthalate-partially oriented yarn) of 130 denier/34 filaments was drawn at 300 m/min with the draw-ratios of 1.76, 1.84 and 2.00 respectively by incremental drawing process (IDP) as well as by the conventional drawing process (CDP) and the properties compared. It was seen that the mechanical and structural properties were significantly better in case of IDP than CDP at equivalent draw-ratios. The mechanical property results are explained on the basis of structural development during drawing.
Drawing Behavior of Solution Modified Polyethylene
Authors: Malik T. M. , Carreau P. J. , Schreiber H. P. , Rudin A. , Tchir W. 
Published: December 2013

Abstract
The relationship between draw ability of high density polyethylene (HDPE) and entanglement density in the polymer has been studied by solution modifying the polymer. This involved precipitating the polyethylene from solutions in trichlorobenzene. Entanglement densities of solution modified and control (as received) HDPE were estimated from low-shear melt viscosity data. One and two stage drawing techniques at closely controlled temperatures were applied to form drawn film specimens. It was shown that solution modified versions of HDPE permitted drawing to much higher ratios than the control, and resulted in films with elastic moduli in the 40 GPa range. A relationship is thereby suggested linking polymer entanglement density with mechanical properties attained in the drawing process. Optimization of drawing performance appears to be attainable by controlling entanglement density, through appropriate choices of solvent and of initial polymer concentration in the solutions.
Flow Field Characterization in a Banbury Mixer
Authors: Cheng J. J. , Manas-Zloczower I. 
Published: December 2013

Abstract
A fluid dynamics analysis package – FIDAP using the finite element method was implemented to simulate the flow patterns in a Banbury mixer. A number of different geometries were selected to represent the dynamic motion of the rotors during a repeated mixing cycle. The simulation results were then used to characterize the flow field in terms of a parameter quantifying the elongational flow components. The influence of design and processing variables on the flow characteristics as well as on the average shear rate were analyzed.
Deformation Fields and Residence Time Distributions in Polymer Melt Flows
Authors: Hannachi A. , Mitsoulis E. 
Published: December 2013

Abstract
In past numerical simulations of polymer melt flows, the flow field has been visualized through velocity vectors and streamlines providing a steady-state Eulerian viewpoint. This work shows that enhanced understanding of flow kinematics can be achieved by calculating the residence time distribution (RTD) of material points through the integration of the known velocity field and by plotting isochrones and the deformation field of fluid elements. Such kinematic patterns provide a Lagrangian viewpoint of the flow and fully describe the history of the elements of the system as they move through the field. In cases with zones of recirculation the period for one revolution is also calculated. Typical examples are shown for such polmyer processing operations as entry flows in contractions, exit flows from dies, calendering and wire-coating coextrusion processes.
Flow History – Morphology Development in Crystallizable Polymer Melts
Authors: McHugh A. J. , Khomami B. 
Published: December 2013

Abstract
Flow history-morphology interactions have been studied for three crystallizable polymers: high density polyethylene, poly(vinylidene fluoride), and polypropylene. Materials were extruded through an impinging channels film die which produces a mixed extensional and shearing flow field. Extrudate morphology was characterized by optical microscopy and x-ray diffraction. Stress fields during die flow were measured from flow birefringence and compared to calculations based on the power law model. Good quantitative agreement was found for the shearing stresses, however, large differences were observed between the measured and computed normal stresses along the symmetry axis of the flow where extensional gradients are also the highest. Extensional stresses on the order of 2.8·106, 1.4·106, and 3.9·105 dynes/cm2 were required to induce row-nucleated crystallization in the HDPE, PVF2, and polypropylene respectively. The respective stresses were found to decrease with increasing relaxation time in a non-linear fashion. An explanation for this behavior is presented based on the opposing tendencies of chain relaxation and oriented crystallization.
Rheological Studies on Solutions of Poly-p-phenylene Terephthalamide in H2SO4
Authors: Xu Y. , Qian R. 
Published: December 2013

Abstract
The material functions, viscosity η, the first normal stress function N1, dynamic shear moduli G′ & G″ from sinusoidal oscillatory measurements and the transient responses of stress build up and stress decay in step flow were investigated experimentally for solutions of poly-p-phenylene terephthalamide in H2SO4 at concentrations from 0.5 to 10 wt.-% covering the phase transition from isotropic to nematic LCP solutions at 8 % where all mentioned properties change abruptly. General analytical forms have been found for η and η* functions. LCP solutions show high value of N1 which builds up at shear strain larger than the yield value of 2. The structural origin for the observed rheological properties are discussed.
Spreader Blade Analogy of Flow Past an Internal Mixer Rotor
Authors: Nassehi V. , Freakley P. K. 
Published: December 2013

Abstract
This paper deals with the finite element modelling of non-isothermal flow of a power-law fluid past an internal mixer rotor. The model uses a set of boundary constraints which correspond to stressfree surfaces at the inlet and the outlet of the domain. At the walls of the domain the conditions of no-slip, controiled-slip and perfect-slip are alternatively incorporated in the simulations. A stream-line upwinding technique used in the solution scheme enables it to yield convergent results for high Peclet No. flow, even if relatively coarse meshes are used. Comparison of these results with the available experimental evidence confirm the general validity of the methods used.
Non-Newtonian and Non-Isothermal Modeling of 3D-Flow in an Internal Mixer
Authors: Kim J. K. , White J. L. 
Published: December 2013

Abstract
In previous work we have applied hydrodynamic lubrication theory to simulate 3-dimensional flow of a polymer melt or elastomer in an internal mixer. That study presumed isothermal Newtonian flow in a flattened out mixing chamber. In the present paper, we take into consideration both non-Newtonian flow properties of the melt/elastomers and increase in temperature due to viscous dissipation heating. We consider the influence of non-Newtonian viscosity on flow patterns in the internal mixer. Viscous dissipation heating in the internal mixer is also modelled. It is shown that large scale internal mixers tend to operate adiabatically while small scale machines are close to isothermal. Temperature-time profiles are predicted for laboratory and large scale internal mixers.
Mixing in Non-intermeshing Twin Screw Extruders
Authors: Bigio D. , Baim W. , Wigginton M. 
Published: December 2013

Abstract
Twin Screw extruders are operated typically in the starve-fed mode, with regions of channels partially-filled with polymeric materials. Although much has been done to understand and characterize the process of devolitalization and polymerization, many of the models have been based on simple mixers like batch mixers or continuous stirred reactors, not on the complex flow patterns found in twin screw extruders. Accurate models of the entire process requires appropriate modelling of the nature of mixing in a partially-filled channel. This paper presents results of a visual study of the counterrotating, non-intermeshing twin screw extruder operated with partially-filled channels. The experiments characterize the nature of mixing and the effect due to screw flight stagger and fluid viscosity.
Simultaneous Diameter and Thickness Control in Tube Extrusion
Authors: Defaye G. , Caralp L. , Delfanne B. , Labaig J. J. 
Published: December 2013

Abstract
In recent years, many applications of process control to extruders have concentrated on the control of temperature and pressure in the die. This study investigates the simultaneous control of the two-dimensional characteristics of a tubing. An identification and control package is used. The system is shown to be non-interacting.
Processing and Properties of Polycarbonate/Liquid Crystal Polymer Blends
Authors: Valenza A. , La Mantia F. P. , Paci M. , Magagnini P. L. 
Published: December 2013

Abstract
Rheological and mechanical properties, structural characteristics, extrusion and injection molding behavior of blends of polycarbonate (PC) with a thermotropic, wholly aromatic copolyesteramide have been investigated. The processability of polycarbonate is remarkably improved by addition of small contents of liquid crystal polymer. All the flow curves of the blends lie between those of the pure components. In the processing conditions adopted, the LCP particles are easily elongated in the flow direction. In this direction the elastic modulus rises remarkably with LCP content. The modulus-composition curve is, however, lower than that expected on the basis of an additive rule due to the incompatibility and poor adhesion between the two phases. Finally, injection molding of this extrusion grade PC has been easily performed by adding small contents of LCP. The impact strength values of the injection molding samples of these blends are only slightly lower than that of the pure PC.
Scale-up Effect in Internal Mixers
Authors: Kawanishi K. , Yagii K. , Obata Y. , Kimura S. 
Published: December 2013

Abstract
In the development of a new polymer and a new compound, mixing equipment plays an important role. However, the properties of a compound tend to vary depending on the size and shape of the equipment used and a means to obtain the same compound by a small scale laboratory mixer as the one obtained by a large scale mixer has been longed for a long time.
As a rubber compound is characterized by the physical properties, they are affected both by the dimensions and shape of the equipment and the mixing conditions. Recently, we developed a laboratory mixer generally following the designs of FH Banbury with exchangeable rotors and mixing chamber blocks which enable us to investigate the influences of the shape of equipment as well as the mixing conditions.
In analysing rubber mixing, we found that the following factors should be taken into account, that is, unit-work which is the applied energy to the unit volume of the material during mixing, Mooney viscosity of the compound, bound rubber which is the amount of polymer unextractable from the compound by a solvent, and weight average molecular weight of polymer extractable by a solvent. If the values of the four factors are close enough for the two compounds obtained by different mixers of different size and shape, one may regard them as the same compounds. Furthermore, we experimentally measured the four factors for the compounds of typical formulations of three species of commercially available rubbers, that is, styrene butadiene rubber, ethylene propylene rubber and butadiene, and expressed the values of the factors as functions of mixing conditions and the parameters of rotor shapes by means of multiple regression analysis. Among the rotor parameters, the following showed significant effects: tip clearance, tip width, total bulkiness and wing overlap ratio. As for the mixing conditions, mixing time, rotor speed and mixing temperature were dominant.
Using the functions obtained by the above mentioned method for the laboratory scale mixer, we tried to find the combinations of rotor shapes and mixing conditions that reproduced the compound mixed by large scale mixers. The optimum parameters of a laboratory mixer for the reproduction of the mixing of an industrial mixer were found to be larger rotor tip clearance, larger rotor tip width, larger wing overlap ratio, higher mixing temperature, and higher rotor speed than those of proportionally reduced dimensions and comparable conditions.