bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow Balancing in Extrusion Dies for Thermoplastic Profiles
Authors: Nóbrega J. M. , Carneiro O. S. , Oliveira P. J. , Pinho F. T. 
Published: December 2013

Abstract
To achieve a specified geometry for an extruded profile, together with a minimal degree of internal stresses, flow balancing of the die is required. To attain this objective, the flow along a profile die channel must be accurately described, and this demands a computational code able to predict complex 3D non-isothermal flow patterns. In this work new methodologies for flow balancing are implemented and illustrated. The design code developed to carry out the automatic search of a final geometry consists of an optimisation routine coupled with geometry and mesh generators and a 3D computational code based on the finite volume method. The issues discussed and described here encompass recent developments, namely the implementation of two alternative optimisation algorithms for the automatic search of a final solution, the enhancement of the strategies previously developed to balance the flow, some improvements in the routine used to generate the mesh and the adoption of a progressive mesh refinement technique. The examples show that the proposed methodology performs well and the solution is attained in just a few minutes of calculation without any user intervention during the calculation process.
Flow Balancing in Extrusion Dies for Thermoplastic Profiles
Authors: Carneiro O. S. , Nóbrega J. M. , Oliveira P. J. , Pinho F. T. 
Published: December 2013

Abstract
To achieve a specified geometry for an extruded profile with minimal level of stress gradient induced by pulling, flow balancing of the die is required. To fulfil this requisite, a set of operating conditions and polymer rheological properties is considered during the design step. However, fluctuations of the operating conditions and/or slight variations of the polymer rheological properties are expected to occur during long-term production. Their effect on the performance of an extrusion die will depend, among other things, on the sensitivity of the flow distribution within the die. In this work, an extrusion die is optimised (balanced) using four different design methodologies and the final shapes of the die are compared in terms of their absolute quality (when used in the optimal conditions) and stability to the factors considered. For this purpose, a finite-volume based computational code is used to perform the required simulations of the non-isothermal three-dimensional flows, under conditions defined by a statistic Taguchi technique. The influence of some operating conditions on the flow distribution is assessed and the effect of the polymer melt rheology is also investigated. It was concluded that the use of different design methodologies lead to different results in terms of flow balancing and sensitivity to the factors considered and that the most balanced and stable extrusion die was that generated by the strategy based on the parallel zone thickness control.
Cross Channel Flow Velocity and Motion Trajectory of Polymers in a Helical Channel
Authors: Sikora R. , Sasimowski E. 
Published: December 2013

Abstract
In reference to the comparison of polymer flow along the helical channel in the screw-based plasticating system in dependence from a kinematical system, which was presented in the previous publication [1], further comparative studies on these models in the range of cross channel flow and resultant flow were conducted. Studies were carried out for both previously described models that is the model with a rotating barrel and the model with a rotating screw. It was stated that polymer cross channel flow velocity and its distribution is different in both models and in both coordinate systems (rectangular coordinate system and helical coordinate system). In a rectangular and helical coordinate system the highest values of the drag (redrag) cross channel flow velocity are the same, the differences occur in the distribution of these velocities. The distribution of the pressure flow velocity is different in both coordinate systems. The conducted analysis of the resultant flow lets us state the differences in the motion trajectory of the polymer particle in both compared models. The spiral lead of the motion trajectory of the polymer particle is higher when the barrel rotates than in the model with a rotating screw. The cause of it lies in different barrel and screw peripheral speeds. Different senses of rotation of the barrel and the screw cause laevorotatory helical motion trajectory when the barrel rotates, and dextrorotatory when the screw rotates, whereas the behaviour of the polymer particle in the vicinity of the screw flight - change of direction by π/2 is the same.
Experimental Development of Processing Technology for Yuba-like Films Using Twin Screw Extrusion
Authors: Hwang S.-L. , Liu S.-J. , Chen W.-L. , Wang C.-Y. , Chou S.-W. 
Published: December 2013

Abstract
The traditional method of making yuba has several shortcomings, including complicated processes, longer processing time, requirement of many equipments, creation of uncomfortable working environments, and production of wastes. To solve these problems, extrusion may be a promising alternative. The techniques of making yuba-like films by using a twin-screw extruder with special forming dies were investigated in this study. The effects of raw materials, plasticizers, operation parameters, and forming dies on twin-screw extrusion of yuba-like films were also analyzed. The results showed that yuba-like films could be made successfully by using a twin-screw extruder with T-die. To achieve a good performance of yuba extrusion and to get a good quality of films, the heating temperature of the raw materials should be over the denaturation temperature of soy protein, and the screw speed/feed rate ratio should be taken into account. Finally, a twin-roller system should be used to extend the films.
A New Design Method to Improve Flow Uniformity in a Reaction Injection Mold Entry
Authors: Hsieh Y. C. , Chen L. L. , Tseng S. C. 
Published: December 2013

Abstract
Reaction injection molding involves the injection of two or more kinds of liquid polymers into a mold at relative high speed. Such high inertia effect may result in air pocket inside the mold or non-uniform velocity distribution. How to design the mold entry geometry to provide uniform velocity distribution becomes one of the major topics in reaction injection molding process. Thus a new and simple method was developed in this work to optimize the reaction mold entry design. Several regulation islands were located in a fish tail entrance to help distribute the flow more even. Dimensions and locations of the islands will affect the flow uniformity and become the factors to be optimized. Taguchi's design of experiments coupled with computer flow simulation was used to achieve die geometry optimization. Effects of different dimensions of the islands on the flow uniformity can also be evaluated through statistical analyses in the flow simulation. Flow visualization technique was done by capturing flow images with high speed CCD. The experimental results showed very good agreements with the Fluent simulation results. The design methodology proposed here can help the molders in designing different reaction injection mold entries for better uniformity and performance.
Easy Tear Film of Biaxially Oriented PA 6/MXD 6 Blend by Double Bubble Tubular Film Process
Authors: Takashige M. , Kanai T. , Yamada T. 
Published: December 2013

Abstract
In the market, a film which adapted to environmental and barrier problems is desired. This report discusses the stretching stability and physical properties for biaxially oriented PA 6/ MXD 6 blending film produced by double bubble tubular film process. As MXD 6 blending ratio increased, the stretching stress decreased. Hydrogen bond is due to be suppressed by the steric hindrance of the MXD 6 resin. Blending film can be stretched stably and oxygen gas permeability is more excellent than PA 6. Further the film blended between 20 % and 40 % as MXD 6 blend ratio has the property of easy straight line cut. It is found that the plate-like cylinder structure was formed in the observation of TEM. However, thickness uniformity deteriorates when MXD 6 blending ratio exceeds 40 %. To improve the thickness uniformity, the influence of the kneading conditions was studied. When the melting point of MXD 6 decreased, the stretching stability deteriorated and mechanical properties drastically lowered. The excess reaction of the blending resins is not desirable. Stretchability, easy tear property and oxygen gas barrier property are maintained by following process conditions. In case of dry blending, MXD 6 30% is proper content. And in case of premixing, MXD 6 melting point keeps over 236°C. It was confirmed that there is the condition satisfying all properties. The blending film keeps the compatible performance of strength and easy tear property. Namely, the material and production technology of a film could solve environmental and barrier free problems.
Stretchability and Properties of Various LLDPE for Biaxially Oriented Film
Authors: Uehara H. , Sakauchi K. , Kanai T. , Yamada T. 
Published: December 2013

Abstract
Stretchability and properties of linear low density polyethylene (LLDPE) blends for biaxially oriented film was investigated in the previous report [1]. That report focused on changing the film density by blending three different densities of LLDPE. The relationship among stretchability, film density and the composition distribution was explored. In this report, several different densities and melt flow indices (MFI) of LLDPE were examined. A film with a density of about 0.915 g/cm3 displayed the best stretchability, while films not less than 2 g/10 min MFI had poor stretchability. The most suitable composition distribution for stretching was reported. The properties of biaxially oriented films were also evaluated. Furthermore, the relationship between the laboratory tenter stretched film (LTSF) and the double bubble tubular film (DBTF) was investigated. There was a correlation between the density in film over 0.910 g/cm3 and the stretchability of the DBTF and LTSF.
Modeling the Flow in the Metering Zone of Single Screw Extruders Using a Helical Geometry Model
Authors: Ghoreishy M. H. R. , Nouri M. Razavi 
Published: December 2013

Abstract
This research work is devoted to the development of a finite element model for the simulation of the flow of polymer melts through the metering zone of single screw extruders. The sets of the governing equations (flow and energy) were solved using the continuous penalty scheme and a streamline upwinding Petrov-Galerkin method, respectively. The non-Newtonian rheological behavior of the fluid was also taken into account by the use of the power-law model. The novelty of this work is the application of this model on the flow of a polypropylene melt through the helical geometry of a single screw extruder. To validate this model, the results of the computer simulations were compared with experimentally measured mass flow rate and also results from a previous model, which was based on the simulation of the flow in a flat flow domain. Comparisons showed that not only there are very good agreements between the model predictions and actual data but also inclusion of the curvature of the screw flights has an important influence on the accuracy of the results.
Index for Simultaneous Dispersive and Distributive Mixing Characterization in Processing Equipment
Authors: Alemaskin K. , Manas–Zloczowe I. , Kaufman M. 
Published: December 2013

Abstract
Computer simulation of agglomerate dispersion and sequential distribution of all particles obtained in the system allows us to evaluate the overall mixing efficiency of processing equipment. Evaluation was based on a specific mixing index, calculated using the Shannon entropies for different size fractions. The index can be tailored to give preference to different particle size distributions, thus relating the quality of mixing to specific properties of the final product.
Viscoelastic Properties of Flexible Organic Fiber Composites
Authors: Hausnerová B. , Zdražilová N. , Kitano T. , Sáha P. 
Published: December 2013

Abstract
In this paper, molten high density polyethylene (HDPE) was compounded with four kinds of high performance organic fibers: two types of aramid (KF29 and KF49), liquid crystalline polymer (LCP) and poly(vinyl alcohol) (VF), differing in their chemical structure and fiber lengths. From the SEM pictures, it is observed that shape and size of these organic fibers maintained almost the same even after cutting in pellets, following the mixing process. VF/HDPE and LCP/HDPE systems show generally lower rates of increase of both storage modulus and dynamic viscosity with fiber content than KF/HDPE composites. Comparison of these functions at the fixed fiber content has shown that the most effective parameter, affecting the viscoelastic behaviour of organic fiber filled systems, seems to be their rigidity/flexibility in the molten state. The influence of fiber rigidity/flexibility becomes gradually lower with the increase of both strain amplitude and angular frequency. The parameters of the equations describing relationship between relative values of viscoelastic functions and fiber content were found to be largely dependent on fiber content. Such finding remarkably differs from behaviour of short inorganic fiber filled systems, where these variables maintained constant values.
A Constitutive Analysis of Extensional Flow of EVA Nanocomposites
Authors: Pasanovic-Zujo V. , Gupta Rahul K. , Bhattacharya S. N. 
Published: December 2013

Abstract
Linear and nonlinear oscillatory and extensional flow was studied for polymer layered silicate nanocomposites of organically modified bentonite in ethylene-vinyl acetate copolymer with 18 wt.% of vinyl acetate (EVA18). It was found that the rheological properties of EVA18 nanocomposites were distinctly different from the pure copolymer. The elastic response at low frequencies was significantly enhanced in comparison to that of pure EVA18. The linear to nonlinear transition for stress relaxation measurements and the damping function were examined. The relaxation spectrum was shifted toward the longer relaxation time scales for EVA18 nanocomposites, while the dependence of the damping for EVA18 nanocomposites was much stronger than that of the EVA18. In contrast, the uniaxial extensional viscosity of EVA18 nanocomposites gave weaker strain-hardening properties. The prediction of strain-hardening behaviour for EVA18 and EVA18 nanocomposites through relaxation spectrum and the damping function based on Kaye-Bernstein-Kearsley-Zapas (K-BKZ) model is discussed. A simplified estimation of the nonlinear material parameter ß in the K-BKZ model is proposed to predict more accurately the extensional viscosity for EVA18 and EVA18 nanocomposites. Experimental data and detailed predictions are also presented in this paper.
Algorithms for Two Gate Optimization in Injection Molding
Authors: Zhai M. , Lam Y. C. , Au C. K. 
Published: December 2013

Abstract
In injection molding, the injection pressure is often limited by the capacity of injection machines. Therefore, for large-volume part, multiple gates are needed so that the maximum flow path can be shortened, with a corresponding decrease in injection pressure. Many components produced by injection molding today require more than one gate. As multiple gates affect resin flow in a mold interactively, their locations might not be easily determined. For a mold with two gates, a pressure gradient search scheme (PGSS) is proposed to optimize their locations in this investigation. A search direction associated with pressure gradient is developed based on the physical nature of the mold-filling process. An alternative scheme based on genetic algorithm is also employed for comparison. Through minimizing the objective function of injection pressure, the optimum gates can be located to achieve balanced flow. Examples indicate that the proposed pressure gradient search scheme is more efficient than genetic algorithm for two gate location optimization.
Preparation and Characteristics of Reactive Blends of Phosphate-containing Maleimide and Epoxy
Authors: Shu W. J. , Hoang K. C. , Chiu H. J. 
Published: December 2013

Abstract
Three kinds of phosphate-containing maleimide(PMI) monomers, namely diethyl (4-(N-maleimido) phenyl) phosphate (4P) diphenyl (4-(N-maleimido) phenyl) phosphate (PP) and diethyl (2,6-dibromo-4-(N-maleimido)phenyl) phosphate (BrP), were synthesized and blended with a phenol-novolac type of epoxy so as to study their potential as reactive flame retardants. Thermal reaction of these blending systems had been discussed. Mechanical and thermal properties of blends had also been analysed. It was expected that with an increase in the PMI content in the blending system, the Michael-addition reaction would take place more and easily. Increasing the PMI contents reduced the storage modulus, the Tg and the tensile strength, however good thermal stability was maintained. The flame retardancy of all the phosphate-containing epoxy systems was promoted significantly by increasing the PMI content. Besides, the PMI with halogen atom may combine the flame retarding mechanism of gas-phase and solid-phase to promote their flame retardancy.
Monitoring Reactive Processes along the Extruder
Authors: Covas J. A. , Machado A. V. 
Published: December 2013

Abstract
This paper reports data obtained from monitoring the evolution of chemical conversion and morphology during the production of a compatibilized polymer blend of PA 6/EPM/EPM-g-MA and of modified polyolefins (grafted with MA) in a co-rotating twin screw extruder. In the first case, the MA content of the modified rubber decreases strongly to almost zero-level and the particle size reduces dramatically from mm to sub-lm level already in the melting zone. The process seems to be mainly influenced by the local flow characteristics, as they assure efficient generation and renewal of interfacial area. In the second case of MA grafting, a similar evolution is observed regardless of the polyolefin type but, for this kind of reactions, temperature and residence time play an important role.
A brief presentation of the on-line monitoring tools used in the above studies is also included.
Visualization Analysis of Asymmetric Fountain Flow Phenomenon in Injection Molding of Filler-reinforced Resins by Rotary Runner Exchange System
Authors: Yokoi H. , Kanetoh Y. 
Published: December 2013

Abstract
In this study, we attempted to visualize the flow patterns inside molded samples of glass-fibers or talc reinforced GPPS and PP especially in the vicinity of the flow front, using a rotary runner exchange system which instantaneously switches melt flowing into the cavity. From the visualization results, an extremely characteristic flow behavior was seen at the flow front area for resins with fillers which was not observed for those without fillers. Especially in the case of resins with 40 wt.% talc or 30 wt.% GF, a-symmetric zigzag fountain flows were generated alternately upward and downward along the cavity width direction. Moreover along the outer layer of the flow front, one observed a large amount of residual resin remaining for a long time during the cavity filling process, in the case of 40 wt.% GF, primarily due to the increase of viscosity which restricts the occurrence of diverging flow. Based on the above visualization results, we proposed a generic model of zigzag fountain flow; an a-symmetric upward flow in a certain area starts preventing the fountain flow in the upper side of the adjacent area, causing the diverging center to sink. This phenomenon subsequently causes an a-symmetric flow in the opposite direction in the next adjacent area, which continuously propagates along the cavity width direction.
The Gloss of Injection-Moulded Recovered Polypropylene
Authors: Pisciotti F. , Boldizar A. , Rigdahl M. 
Published: December 2013

Abstract
In our recent work, it was shown that the rate of filling during injection moulding did not significantly affect the tensile and impact properties of recovered and virgin polypropylene, whereas significant changes in the properties were observed after ageing at 100 °C. The purpose of the present work was to extend the former study to include the effects of processing and ageing on surface-appearance-related properties, in particular the gloss. In-mould rheology and gate-seal analyses were performed in order to select the filling and post-filling processing windows, respectively. The influences of filling rate, holding and cooling times on the gloss measured in the gate area and at the far end of the moulded specimens were evaluated. The mould used had an embossed surface giving test plaques with a matte appearance. The results showed that the gloss varied by about 30 to 40% within the filling window obtained by in-mould rheology. The slight gloss difference between the two PP-grades noted at the lowest injection speed vanished with increasing filling rate. Gloss differences were observed between the gate area and the far end of each processed moulding, again at the lowest injection speed. The materials processed at a high filling rate exhibited a fairly constant gloss as the holding time increased regardless of the position of the analysed region, whereas a more significant decrease was noted in the case of the mouldings processed at the low filling rate. The cooling time had a negligible effect on the gloss in comparison to the effect of filling rate. Ageing at 100 °C for 240 h increased the gloss level, especially at the far end of the moulding, but only for specimens manufactured at the lowest filling rate. Roughness measurements with a profilometer showed that the gloss development during processing and ageing was related to the topographical matching between the developing polymer surface and the mould topography.
Orientation and Residual Stress Distributions in Thick Melt Spun Polystyrene and Polycarbonate Filaments
Authors: Kang Ho Jong , White James L. 
Published: December 2013

Abstract
A study of orientation development and residual stresses in thick melt spun polystyrene filaments and polycarbonate filaments described. Linear relationships between spinline stress and mean birefringence under different melt spinning conditions were obtained. These results were used together with models of the dynamics of melt spinning to predict the characteristics of thick melt spun filaments. Birefringence distrbutions and residual stresses were computed. High orientations and compressive circumferential residual stresses were predicted at the larger radii and low orientation and tensile circumferential and radial residual stress in the fiber core are obtained. The distribution of birefringence across the thickness of thick melt spun filaments was measured by determining changes of retardation across a wedge. The birefringence distributions were correlated with severity of quench and model prediction. Thick melt spun fibers were peeled and found to have fibrillar cores.
Second Moment Specification of Complex States of Polymer Chain Orientation in Fabricated Plastic Parts
Authors: White J. L. , Cakmak M. 
Published: December 2013

Abstract
A generalized representation of second moment orientation in polymer systems is presented. Orientation is expressed through the asymmetry of the polarizability tensor. The formulation presumes that local symmetry directions differ from macroscopic machine and transverse directions. The formulation leads to a set of biaxial orientation factors (equivalent to those of White and Spruiell) defined relative to symmetry axes I, II, III and a set of angles ϑI1 ϑII2 and ϑIII3 representing the directions of the axes relative to the laboratory axes (1, 2, 3) such as the machine (1), transverse (2) and thickness (normal) directions (3). Any two of these angles eγ, ΘI1 and ΘII2 are sufficient. The formulation is applied to interpret orientation developed in simple shear.