bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gear Pump Performance in Polypropylene Filament Yarn Uniformity
Authors: Shumpert B. B. , Padsalgikar A. D. , Ellison M. S. , Hosangadi G. S. , Henshaw Ian 
Published: December 2013

Abstract
We report the development of a high resolution computerized monitoring system for fiber melt spinning and the results of its application to polypropylene fiber production. Variation in pack pressure caused by the melt pump was found to significantly affect the uniformity of the filament linear density. In this study, the variation in the pack, or gear pump outlet, pressure during polypropylene fiber melt spinning is correlated with various process parameters and the resulting fiber characteristics. We found the coefficient of variation in pump discharge pressure to decrease with increasing pump capacity and pump speed. The coefficient of variation in pack pressure was directly correlated with the coefficient of variation in filament yarn uniformity. Pump wear was found to have a marked impact on the variance in pack pressure.
Effect of Pressure and Shear Stress on Crystallization Behaviors in Injection Molding
Authors: Ito H. , Minagawa K. , Takimoto J. , Tada K. , Koyama K. 
Published: December 2013

Abstract
We studied in detail the effects of pressure and shear stress on the crystallization behaviors during injection molding process. Crystallization of isotactic-polypropylene (iPP) was simulated for various injection flow rates. The crystallization started during the filling stage under long filling condition. Moreover, the crystallization in some layers showed two -step growth behavior, while in other layers the crystallization does not progress during the packing -cooling stage. Since pressure becomes very high during molding process under long filling time condition, the change of pressure is the most important factor governing the crystallization.
Influence of Processing Temperature on the Morphological and Mechanical Properties of a PC/TLCP Blend
Authors: Wang H. , Hinrichsen G. 
Published: December 2013

Abstract
The influence of processing temperature on the morphological and mechanical properties of polycarbonate (PC) blended with a thermotropic liquid crystalline polymer (TLCP) has been studied. At a barrel temperature of 310°C, the TLCP of the blends exhibits the high orientation level and fiber alignment which correspond to maximum tensile strength. This indicates that the processing temperature might result in the change of the viscosity ratios of the dispersed and continuous phase and is one of the main processing parameters.
A New Approach to Simulation of Die Flow which Incorporates the Extruder and Rotating Screw Tips in the Analysis
Authors: Lawal A. , Railkar S. , Kalyon D. M. 
Published: December 2013

Abstract
The traditional method of mathematical modeling of the die flows treats the die as a stand alone tool which is independent of the extrusion conditions which feed the polymer melt into the die. Here, we demonstrate that especially under the conditions where a breaker plate is not used the flow and the deformation which occur in the die are dependent on the prevailing velocity and the stress conditions of the fluid at the extruder which feeds the die. A finite element method based technique is used to solve the conservation equations using a mesh which covers both the die and the rotating conical screw tips of the extruder. The presented methodologies provide a more realistic representation of the thermo-mechanical history experienced by the polymer melt or structured fluids including emulsions or suspensions in the die and thus provide better tools for die design and process optimization. The results also suggest that significant improvements in die design and hence die performance could ensue by using the geometry of the screw tips, the distance between the screw tips and the die and the rotational screw speed as additional parameters for design and optimization.
Numerical Simulation of the Multi-Component Injection Moulding Process
Authors: Zoetelief W. F. , Peters G. W. M. , Meijer H. E. H. 
Published: December 2013

Abstract
The versatility of the injection moulding process can be increased by combining multiple polymers in one product. The multi-component injection moulding process (MCIM) offers the possibility to inject two or three materials sequentially or simultaneously into a mould to make products that consist of e.g. a layered structure. For a successful application of this technique for geometrically complex products or multiple materials, the material distribution in the product has to be predicted. In this paper numerical tools are described for calculating the positions of material particles during the flow in the mould cavity. These tools make it possible to solve the inverse problem of predicting the injection sequence in MCIM given a required material distribution in the product. The simulations are validated using experimental results of a co-injected strip with stiffener ribs. Furthermore the effect of a bifurcation of the midsurface on the material distribution is investigated numerically using a simplified model based on the local mass balance.
Modelling the PVT Behavior of Isotactic Polypropylene
Authors: Hieber C. A. 
Published: December 2013

Abstract
Making use of available data from the literature, a master correlation based upon a two-domain-Tait representation is developed which describes the asymptotic high-temperature and low-temperature PVT behavior of isotactic polypropylene. The transition between these two asymptotes in the cooling mode is then handled based upon the quiescent-crystallization-kinetics equation of Nakamura, employing model constants for the temperature- and pressure-dependent crystallization rate based upon earlier work by the present investigator. As a further step, it is shown that a rule-of-mixtures approach can describe the low-temperature and high-temperature asymptotic PVT behavior equally as well as the 2-domain-Tait model while requiring two less free parameters. In turn, since the rule-of-mixtures representation contains the absolute crystallinity as an explicit parameter, it is proposed that this model might also be used under flow-induced conditions once the corresponding crystallization kinetics become established.
Extension of 2½ D Control Volume Methods for Transverse Flow at Sprues, Gates and Junctions
Authors: Batch G. 
Published: December 2013

Abstract
Commercial injection mold filling simulations use the lubrication approximation to model pressure and temperature during flow. This approximation is valid when flow streamlines are parallel to a cavity surface, such as when the cavity thickness is much smaller than the flow length. Yet this approximation may not be valid in complex cavities where the streamlines are not parallel. Flow through junctions, gates and sprues are always accompanied by a velocity component transverse to the mold surface which is not included in the model. Neglecting transverse flow through use of the lubrication approximation can result in anomalous changes in bulk mean temperature, filling patterns, and molecular and fiber orientation. This paper presents a mass balance algorithm for approximating transverse flow through gates, sprues and junctions. This new algorithm is presently suitable for only relatively simple geometries. Future work will attempt to make a similar algorithm for transverse flow through complex mold shapes with negligible penalty in additional computational run time.
Modular Tangential Counter-Rotating Twin Screw Extrusion: Non-Newtonian and Non-Isothermal Simulation
Authors: Bang D.-S. , White J. L. 
Published: December 2013

Abstract
A non-Newtonian flow model for individual elements of a modular tangential counter-rotating twin screw extruder is developed. A non-Newtonian non-isothermal flow model for a composite modular machine is then described. Fill factor, pressure and temperature profiles along the axis of the twin screw machines were predicted for various modular screw configurations. Finally, experiments were carried out on the modular machine to verify the predictions. Generally, good agreement with the flow analysis was found.
A Parametric Study of Sink Marks in Injection-Molded Plastic Parts using the Finite Element Method
Authors: Battey D. J. , Gupta M. 
Published: December 2013

Abstract
A numerical procedure to simulate the formation of a sink mark near the base of a rib in an injection-molded plastic part has been developed. This method uses two commercially available software packages, C-Mold and Abaqus, to model the injection molding process. The C-Mold software uses a generalized Hele-Shaw formulation to simulate the mold filling, packing and cooling stages of injection molding. From this analysis, pressure and temperature histories in the rib area are derived. These are used to determine the initial conditions and boundary conditions for a sequentially-coupled thermal / structural finite element analysis of a cross-section of the rib, using the Abaqus software. An elastic-plastic material model with temperature-dependent material properties is employed. The thermal/structural finite element analysis provides an accurate model of the two-dimensional cooling and shrinkage behavior of the part during molding. To verify the accuracy of the method, the dependence of sink mark depth on various geometric and molding parameters has been analyzed. The predicted sink mark depth is found to be in good agreement with experimental results from the literature.
Processing of Sheath-Core and Matrix-Fibril Fibers Composed of PP and a TLCP
Authors: Robertson C. G. , Baird D. G. 
Published: December 2013

Abstract
Isotactic polypropylene (PP) was reinforced with Vectra B950 (VB), a thermotropic liquid crystalline polymer (TLCP), in two novel fiber spinning processes which both employ two extruders to allow separate thermal histories to be applied to PP and VB prior to their combination. In one process, a single VB melt stream was surrounded by a sheath of PP, in a manner comparable to a wire coating process, just prior to melt spinning to generate fibers possessing a sheath-core structure. The other process involved the distribution of continuous VB melt streams within a separately plasticated PP melt to form a composite melt which was drawn to create matrix-fibril fibers consisting of a PP matrix reinforced with VB fibrils. Both processes allow polymers with non-overlapping processing temperatures to be combined and melt spun to form composite fibers. The effect of fiber draw ratio on the tensile mechanical properties was assessed for composite fibers reinforced with 50 wt.-% (39 vol.-%) VB. Numerical simulations of the non-isothermal fiber drawing processes and an investigation of fiber morphology were undertaken in order to explain the mechanical properties. The composite fibers were compression molded at a temperature 80°C below the melting temperature of VB to form unidirectionally reinforced plaques. For both fiber types, the plaques exhibited excellent retention of fiber properties, illustrating the potential for using the fibers to form reinforced composite parts.
Application of Neural Networks to Analyze the Drawing Process of PET Films
Authors: Kim H. D. , Kim S. Y. 
Published: December 2013

Abstract
Multilayer feedforward neural networks with error backpropagation algorithm have been applied to analyze the drawing process of PET films. Six kinds of process conditions, four kinds of material structures and six kinds of material properties were used as inputs and outputs chosen to analyze the relationships between process conditions, material structures and properties. It was shown that the trained neural networks represent a small error between the target and the corresponding estimated values. It has been shown quantitatively that material studies play an intermediate role in the relationship between process conditions, material structures and properties. It was also shown that model-free simulator predictions by neural networks are more reliable than the corresponding conventional non-linear regression analysis in the complex polymer processing.
Stabilising the Structure of HDPE by the Use of Highly-dispersed Mixture of Fe/FeO
Authors: Ozden S. , Hhatsukova M. A. , Mashukov H. I. , Kozlov G. V. 
Published: December 2013

Abstract
An oxygen acceptive catalyser Fe/FeO mixture was added to the high density polyethylene (HDPE) at different amounts and the stabilisation effects of this additive on the structure of HDPE was investigated. It was shown that the mechanical behaviour and the temperature stability of HDPE was significantly improved with the application of the additive. The experimental results were found to be in accordance with analytical approaches.
Rheological Behaviour of HDPE/PA 11 Blends
Authors: Dospíšil D. , Kubát J. , Sáha P. , Pavlínek V. , Becker J. 
Published: December 2013

Abstract
This paper presents the results of an experimental study of the unstable capillary flow of HDPE/PA 11 blends with special emphasis on the pressure oscillation region. The main result is the finding that addition of only 1 % by weight of the PA 11 component to HDPE completely suppresses the oscillation phenomenon normally found with the latter polymer when the measurement is carried out in a rheometer with a plane capillary entrance. In comparative experiments with a capillary rheometer with a conical (120°) entrance, the pressure oscillation effect disappeared at a PA 11 content of 5%. In compounds containing 1, 3 and 7 % PA 11, distinct pressure oscillations were recorded in the latter case.
The stress and elongation at break of the extrudates change in a monotonic fashion with the composition. SEM photographs and DSC measurements show that the two components are basically immiscible.
On the Charge State of Melt-Blown Polymer Materials
Authors: Pinchuk L. S. , Kravtsov A. G. , Voronezhtsev Yu. I. , Gromyko Yu. V. 
Published: December 2013

Abstract
Fibrous polymer materials formed by LDPE melt spraying with a gas flow during extrusion were exposed to thermally stimulated depolarization. The analysis of thermally stimulated current spectra and the sample charge state has shown that the fibers possess the spontaneous polarizing charge. IR-spectroscopy has proved the material production to be accompanied by vinylene, vinyl, transvinylene and other nonsaturated groups formation. The latters are, probably, behaving as neutral trapping centers during their interaction with charge carriers formed at melt dispersion by the compressed gas flow and its contact with metal parts of equipment. The kinetics of these processes can be monitored by regulating technological regimes of fibrous material formation. Intensified action on the polymer melt might rise the spontaneous polarizing charge whose density can reach 10−10 to 10−12 C/cm2. Charge of the materials under study is rather stable. It does not fall below 40% upon a 160-days storage in humid atmosphere. It appears thus that the technique of fibrous material production by polymer melt spraying is an electret method.
Melt Flow Instabilities of Filled HDPE
Authors: Dospíšil D. , Kubát J. , Sáha P. , Trlica J. , Becker J. 
Published: December 2013

Abstract
Data relating to the influence of several fillers on flow instabilities in capillary extrusion of two grades of high density polyethylene (HDPE) are presented. Special attention is paid to the pressure oscillation region of the flow curve. First we show that a certain level of flow stabilisation can be achieved with carbon fibres, while carbon black and CaCO3 have a minor influence only on the oscillation effect when varying the filling between 5% and 10%. The temperature used was 200° C and the capillary entrance was plane (180°). We also show that a complete disappearance of pressure oscillations is obtained when using a different HDPE grade filled with 7% fumed silica or carbon black (also different grade). Compounds containing 7% talc did not stabilise the flow. The same was true when the filling was reduced to 3%. In the latter experiments a capillary rheometer with a conical entrance (120°) was used. The temperature was 160°C. Data obtained by frequency analysis of the fluctuating pressure transducer signal mounted on the rheometric equipment, operating in both cases at constant piston speed, are also presented.
Generation of Partially Crosslinked Expanded PP-films and -sheets
Authors: Fritz H. G. , Bölz U. , Lü R. 
Published: December 2013

Abstract
A modified concept for the generation of partially crosslinked expanded PP-films and -sheets, useable in automotive industry, is presented. The paper describes in detail an optimized formulation window for the organosilane crosslinking of the selected PP-copolymers, an adequate plant design for the realization of this innovative processing concept as well as approved process parameters. As derived from experimental studies, gel content and the amount of blowing agent seem to be the most essential parameters with regard to foam structure, foam density and cell size homogeneity.
Continuous Polymerization and Copolymerization of Lauryl Lactam in a Modular Corotating Twin Screw Extruder
Authors: Ha S. K. , White J. L. 
Published: December 2013

Abstract
A study is presented of the polymerization of lauryl lactam and the copolymerization of lauryl lactam and caprolactam in a modular co-rotating twin screw extruder. Lauryl lactam had not been previously polymerized in a twin screw extruder. It was found possible to do this to high molecular weights. Generally, lower screw speeds result in longer residence times and higher conversions and molecular weights. The copolymers produced have broad melting transitions and their melting temperatures and heats of fusion exhibit minima as a function of comonomer composition.
Thermal Polymerization of Methyl Methacrylate at High Temperature
Authors: Fenouillot F. , Terrisse J. , Rimlinger T. 
Published: December 2013

Abstract
Kinetic studies of the bulk polymerization of methyl methacrylate at high temperature have been carried out first without any additives and then in the presence of 1-Butanethiol as a chain transfer agent. A pressurised dilatometric reactor operating at high temperature is used to determine the time-conversion curves at temperatures between 150 and 180°C. A two-stage polymerization is observed. The high polymerization rate obtained initially is attributed to traces of an initiating impurity, while the second, slower polymerization stage could be considered as the actual thermal polymerization. The chain transfer agent or an impurity it may contain also initiates the reaction. Therefore, the rates of both the initial polymerization and of the second stage are increased when the thiol is added.
Experimental data on the degree of conversion versus time and on the final average molecular weight are used to determine the chain transfer constants to the monomer and to the mercaptan as well as the initiation rate constants. These constants are used to model the thermal polymerization of MMA at high temperatures where these initiation reactions can no longer be neglected, especially when an industrial polymerization process has to be optimized and controlled.
Modeling Flow and Fusion of Mixtures/Blends of Polymer Pellets and a Low Viscosity Phase in a Modular Co-rotating Twin Screw Extruder
Authors: Lee S-H. , White J. L. 
Published: December 2013

Abstract
A method of modeling the two phase flow and fusion process for a blend of low viscosity and high viscosity polymers in a modular intermeshing co-rotating twin screw extruder is presented. The delayed melting/fusing process in a large viscosity ratio system is simulated mathematically. Calculations were made for specific modular screw configurations. The screw configurations included both screw elements and kneading disk blocks. The temperature rise in a suspension of low viscosity melted and unmelted solid pellets was calculated along the screw axis. The suspension-blend transition temperature to a blend system was then determined. Furthermore, we tested the usefulness of this model by comparing the simulation with experimental results.
Morphology of Injection Molded Polyacetal during Filling
Authors: Mizuno W. , Tomari K. , Hamada H. , Maekawa Z. 
Published: December 2013

Abstract
The morphology of injection molded polyacetal was investigated using spiral-flow test mold and shear effect on crystallization phenomena is discussed. Morphology differed for skin, shear and core layers. The thickness of the shear layer was proportional to flow time.
Warpage of Injection Moulded Plates and Corner Products
Authors: Jansen K.M.B. , van Dijk D.J. , Keizer K.P. 
Published: December 2013

Abstract
This paper contains a systematic study on warpage of injection moulded plates and corner products as a function of mould temperature difference and holding pressure. The study is restricted to unfilled amorphous materials. As expected, experiments showed that warpage increased linearly with the applied temperature difference between mould halves. Not expected was that at low holding pressures the plates curved towards the hot side, whereas at high holding pressures they warped towards the cold side. A simple thermoelastic theory is proposed which could explain all observations qualitatively and quantitatively. Standard simulation software, on the other hand, was seen to predict warpage behaviour at the higher holding pressures which was completely opposite to the experimental observations.