bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microcellular Wood Fibre Reinforced PP Composites
Authors: Bledzki A. K. , Faruk O. 
Published: December 2013

Abstract
Microcellular wood fibre reinforced polymers have practical significance given the possibility of reducing the density of automotive components due to their microcellular structure, as well as processing and performance advantages. A microcellular foaming process with a chemical foaming agent was applied at an experimental stage to injection moulding, extrusion and compression moulding of wood fibre reinforced polypropylene composites. The focus of the research was to investigate these processes using a chemical foaming agent and to perform comparative studies of the physico-mechanical properties of microcellular materials. The effects of the presence of the chemical foaming agent (exothermic) and variation of its content on density, microvoid content, mechanical properties (tensile and flexural), odour concentration and cell morphology of microcellular polypropylene-wood fibre composites were studied. The morphology, cell size, shape and distribution of the microcells were investigated using scanning electron micrographs. Injection moulding process produced finer microcellular structures in comparison with the other processes. As compared to the non foamed composites, the density reduced maximum 30% (0.741 g/cm3), 20% (0.837 g/cm3) and 22% (0.830 g/cm3) for the injection moulding, extrusion and compression moulding process respectively. The chemical foaming agent reduced the odour concentration in relation to the same non foamed composites. Injection moulding showed better performance in comparison with extrusion and compression moulding in terms of cell morphology, density reduction, odour concentration and mechanical properties.
A Low Force Valve for Dynamic Control of Molten Plastics in a Mold
Authors: Kazmer D. O. , Gupta D. 
Published: December 2013

Abstract
Polymer processing has been limited by the lack of direct flow and pressure control of the polymer melt at multiple points in space and time. Improved axial and radial valve designs are discussed that require negligible actuation force to control the flow of the pressurized melt. The forces resulting from pressure loads and shear stresses are first analyzed for an axial valve pin. Subsequently, a radial valve design is implemented and experimentally characterized using neat polycarbonate. A sigmoidal response surface is fit to the experimental data and found to very well model the observed pressure drop as a function of flow rate and valve pin position. The juncture loss at the valve port is then characterized by estimating and removing the pressure drops in the circular flow segments of the valve. Analysis indicated that the juncture loss is inversely proportional to the exposed area, or vesica piscis, formed between the circular flow channel in the valve body and the flow port on the moving valve pin. While applicable to many different polymer processing operations, the validated models are used to show the dynamic valve pin position as a function of the desired flow rate and desired cavity pressure in the hot runner of an injection mold. Finally, the impact of the designs on lower power, more compact mechanical and control system designs are discussed.
Influence of Drawing and Temperature on the Optical and Structural Properties of Monofilament PP Sutures
Authors: Seisa E. A. 
Published: December 2013

Abstract
The influence of drawing and temperature on the optical and structural properties of monofilament polypropylene sutures (PP) were investigated using interferometry. Two techniques have been used in this study: 1) the polarizing interference microscope, 2) multiple-beam Fizeau interferometry. The polarizing interference microscope is used to study the variation of refractive indices and birefringence of PP sutures at different draw ratios and stresses. The stress-strain diagram of PP sutures was studied. The resulting data was used to calculate the average work per chain, Poisson's ratio, strain optical coefficient, Young's modulus and optical orientation function. Multiple-beam Fizeau interferometry was used to study the temperature effect on optical properties of PP sutures with temperature ranging from 19 to 40°C. Relationships between the optical parameters at different temperatures are given. Calculation of the density, crystallinity, dielectric constant and dielectric susceptibility at different temperatures are done. The results obtained, clarify the effect of drawing and temperature on the structure of PP sutures. Microinterferograms are given for illustration.
A New Calculation Model and Optimization Method for Maddock Mixers in Single Screw Plasticising Technology
Authors: Zitzenbacher G. , Karlbauer R. , Thiel H. 
Published: December 2013

Abstract
A homogenous melt is the prerequisite to achieve the demanded product quality in single screw plasticising technology. At higher screw speeds and mass flow rates solid particles can occur in the melt. Dispersive mixing elements are often used to improve the melt quality. Calculation models are necessary for designing mixing elements in the right way. A new model for the often used fluted mixing sections like axial and spiral Maddock-elements and Z-elements is presented in this paper.
The calculation model is reduced to a single pair of inlet and outlet flute, connected by the shearing gap. Especially in spiral Maddock mixers the longitudinal flow in the flutes is a combined pressure and drag flow but in axial Maddock mixers pure pressure flow occurs. In the shearing gap a combined pressure and drag flow can occur. The leakage flow through the flight clearance is also considered.
Geometry functions are introduced for considering the rectangular or circular segment shaped cross section of the flutes. The viscosity is shear rate and temperature dependent, the channel height as well as the channel width can vary along the mixing element. The model allows the calculation of the longitudinal pressure profile in the inlet and outlet flutes, the total pressure drop and the shear stress distribution in the shearing gap.
Mixing sections sometimes show a too high pressure consumption and insufficient shearing efficiency. Therefore a geometry optimization method for axial Maddock mixing heads is presented in this paper.
Investigations into Kinematic Reversal in Non-isothermal Flows in Single-screw Machines
Authors: Potente H. , Bornemann M. , Heinrich D. , Pape J. 
Published: December 2013

Abstract
When describing the flow in single-screw machines in mathematical terms, the screw is generally assumed to be standing still inside a rotating barrel. This study looks into whether and, if so, how far this principle of kinetic reversal falsifies the calculation result. It is performed both on an analytical basis and with the aid of comparative FEA simulations, taking the general case of a non-isothermal flow. It is shown that both kinematic boundary conditions lead to absolutely identical calculation results.
Residual Wall Thickness Distribution at the Transition and Curve Sections of Water-assisted Injection Molded Tubes
Authors: Liu S.-J. , Hsieh M.-H. 
Published: December 2013

Abstract
Water-assisted injection molding technology has been used to manufacture plastic tubes in recent years, due to its light weight, relatively lower resin cost per part and faster cycle time. The residual wall thickness around dimensional transitions and curved sections can significantly affect the strength of molded parts and is of great concern. This research investigated the uniformity of the residual wall thickness distribution in water-assisted injection molded circular tubes with dimensional variations and curved sections. Experiments were carried out on an 80-ton injection-molding machine equipped with a lab scale water injection system, which included a water pump, a pressure accumulator, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The material used was semi-crystalline polypropylene. It was found that the wall thickness was not uniform near transitions. With the addition of fillets with proper angles around transitions, the uniformity of residual wall could be greatly improved. The residual wall thickness in curved sections was thick around the outer wall and thin around the inner wall. In addition, the experimental results suggest that water-assisted molded parts exhibit a more uniform thickness distribution at transition and curved sections than in gas-assisted molded parts.
Correlation between Injection Molding Parameters, Morphology and Mechanical Properties of PPS/SEBS Blend Using Artificial Neural Networks
Authors: Lotti C. , Bretas R. E. S. 
Published: December 2013

Abstract
The objectives of this work were to identify the injection molding processing variables with the greatest effect on the morphology and mechanical properties of an injection molded blend made of poly (p-phenylene sulphide), PPS and block copolymer styrene-ethylene-butadiene-styrene ‘SEBS’. Artificial Neural Networks, ANNs, are used as an alternative method to constitutive and empirical models, to predict morphological features and mechanical properties from the injection molding conditions, and to predict mechanical properties from the morphological features.
The quantification of SEBS dispersion in the PPS matrix was done using a dispersion function. Mold temperature and flow rate were the processing variables with the highest influence on the entire morphology, while the holding pressure influenced mainly the inner layers. Impact strength and toughness were most influenced by mold temperature, holding pressure and the outer layers. The flexural modulus was influenced by all processing variables and the intermediate layers.
Three different ANNs were evaluated: one (ANN-1) to predict morphology from processing conditions and another two to predict mechanical properties from morphology and from processing conditions (ANN-2 and ANN-3, respectively). These latter ANN models had similar results, indicating that both inputs could be successfully used to predict mechanical properties, as the mean residuals were close to experimental errors. On the other hand, ANN-1 showed a lower performance, with a mean error smaller than the experimental error, suggesting that ANNs could overtake some inherent uncertainties.
In this case, it was concluded that the distribution of data along output domain was more important than a high number of training data in the ANN's performance.
Dynamic Mold Surface Temperature Control Using Induction and Heater Heating Combined with Coolant Cooling
Authors: Chen S. C. , Jong W. R. , Chang J. A. , Chang Y. J. 
Published: December 2013

Abstract
In this study, both electrical heater heating and electromagnetic induction heating combined with coolant cooling are developed to achieve a dynamic mold surface temperature control. Simulation tool was also developed by integration of both thermal and electromagnetic analysis modules of ANSYS. The capability and accuracy of simulations on the heater heating and induction heating were verified with experiments. To evaluate the feasibility and efficiency of heater heating and induction heating on the mold surface temperature control, a mold plate, roughly about an inset size of cellular phone housing, installed with five heaters and designed with four cooling channel with coolant running through, was utilized for the demo experiments varying mold surface temperature between 110 °C and 200 °C. During induction heating/cooling case, it takes 4 s to increase mold surface temperature from 110 to 200 °C and it takes another 21 s for mold surface to cool down to 110 °C. The mold plate surface temperature can be raised at about 22.5 °C/s and cooled down at 4.3 °C/s within the mentioned temperature range. Mold plate temperature distribution exhibits good uniformity as well in all stage of heating/cooling process. For heaters heating, it takes 37 s to increase mold surface temperature from 110 to 200 °C and it takes another 30 s for mold surface to cool down to 110 °C. The temperature rising rate is only about 2.4 ° C/s. Induction heating is more efficient in mold surface temperatures control than electrical heating and it does eliminate the weld line mark when applied to a tensile test mold with double gate design prior to melt injection.
Visualization of Melt-Flow Behavior Inside the Runner in Ultra High Speed Injection Molding
Authors: Hasegawa S. , Yokoi H. 
Published: December 2013

Abstract
Ultra-high-speed injection molding is a highly effective technique for realizing very thin-walled molded parts; its application to the production of new high value-added products is anticipated. The melt-flow behavior in ultra-high-speed injection molding is expected to differ from that in conventional molding. However, thus far, very few studies pertaining to the phenomena occurring within cavities and runners at such high filling speeds have been reported, thus necessitating the direct observation of melt-flow behavior inside the molds.
In this study, we attempted to dynamically visualize the melt-flow behavior at the runner split portion, especially under ultra-high-speed injection molding. Visualization experiments were conducted using a glass-inserted mold, which was modified from the original visualization mold structure in order to improve the pressure endurance of the glass-inserted visible area. This paper discusses the visualization analyses of melt-flow behavior in two types of experimental split runner systems (three inclined split runners and cross-shaped runners in a cascade layout). The behavior at the runner split area was studied under low to ultra-high-filling rates. The analyses clarified the effects of inertia at the runner branching point, which has not been verified in general injection molding, and the consequent changes in the filling behavior.
A New Scheme for Controlling Part Cooling in Injection Molding
Authors: Hernandez J. M. , Dubay R. , Pramujati B. 
Published: December 2013

Abstract
Part cooling parameters such as coolant flow rate and coolant temperature has been shown to have an important influence on the part quality in plastic injection molding. Molders commonly manipulate the coolant flow rate in an unclear manner to adjust part quality and reduce the overall cycle time. Manipulating such parameters effectively can indirectly control part quality when deviations in the injection processing variables occur if it is done in a controlled manner. In this investigation, coolant flow rate is selected to be the manipulated variable that affects an average temperature of the part surface as it cools within the mold cavity. The average part temperature is the controlled variable and its control represents the indirect control of part quality. Experiments were conducted to quantify the effects of coolant flow rate on the part surface temperature demonstrating that it is highly nonlinear and its control would require an advanced control scheme. An adaptive online modeling algorithm that uses information from temperature and flow rate sensors was developed to continuously retune a predictive controller for controlling the part surface temperature. Good control performance was obtained from the adaptive strategy for tracking setpoint changes in the part temperature and when the cooling cycle was reduced from 16 to 14 s.
An Integrated Approach for Numerical Analysis of Coupled Flow and Heat Transfer in Co-rotating Twin Screw Extruders
Authors: Kalyon D. M. , Malik M. 
Published: December 2013

Abstract
The co-rotating twin screw extrusion process is widely employed in chemical industries for the processing of complex fluids including various polymers, suspensions, emulsions and gels. Here we propose a new integrated modeling strategy that is based on the numerical analysis of pressure-generating extrusion elements concomitantly with the pressure-losing extrusion elements of the co-rotating twin screw extrusion process for non-Newtonian fluids under nonisothermal conditions. The numerical analysis undertakes three-dimensional (3-D) finite element simulations of any multiple combinations of forwarding and reversing fully-flighted screw elements with other types of elements including kneading discs staggered in the forward or reverse configurations and the die. The abilities of the methodologies in simulating the coupled flow and heat transfer in industrially-relevant mixing sections or pressurization/die shaping are demonstrated with predictions of the degree of fill and typical velocity, deformation rate, stress magnitude, pressure distributions as functions of various operating parameters and basic twin screw extrusion geometries for a viscoplastic type generalized Newtonian fluid.
Relationship Between Structure and Spinning Processing of As-Spun PP Fibres
Authors: Yang R. D. , Mather R. R. , Fotheringham A. F. 
Published: December 2013

Abstract
As-spun polypropylene (PP) fibres, obtained under a one-step statistical experimental design using orthogonal arrays and involving all the common spinning parameters were studied with wide angle X-ray scattering (WAXS). The WAXS results revealed that the micro-structure of PP fibres can be altered progressively from less-ordered para-crystalline states to highly-ordered crystalline states with an α-monoclinic lattice. The degree of structural order has been evaluated quantitatively in terms of (W½)−1, the reciprocal of the half-height width of the first WAXS reflection peak. On the basis of such quantitative evaluation, which is shown to be consistent with the conclusions derived from “traditional” qualitative assessment, comprehensive quantitative analysis of the effects of processing parameters and their interactions on the degree of structural order is accomplished, using systematic but simple statistical methods. Parameters significantly affecting structure, including types of raw materials, winding speed, spinning temperature, application speed of spin finish and metering pump speed are identified, and correlation between structure and parameter setting is established in a concise statistical model. The model indicates clearly the combination of parameter levels for increasing or reducing the degree of structural order over the whole range from essentially amorphous to highly crystalline forms. Comparisons with the “conventional” approach of “one factor at a time” demonstrated the validity of the new approach and its significant advantages. The latter includes the economy in experiment scale, efficiency in result analysis and a comprehensive overview of the process being studied, which covers effects arising from synergistic interactions as well as from individual parameters.
Wave Behavior in the Coating Process of Multilayer Polymeric Materials
Authors: Su Y.-Y. 
Published: December 2013

Abstract
A mathematical analysis model of multilayer viscoelastic fluids flowing down an inclined plane for any arbitrary wave numbers has been established to improve multilayer product quality in the coating processes. In the stability study of the free surface with small elastic force, Reynolds number is the primary parameter to induce surface instability for long and intermediate waves. When the elastic force in either layer is large, elasticity can affect the stability of long and intermediate waves. In addition, viscosity stratification across the interface can also affect the stability of the free surface. For the interfacial stability of two-layer flow system, it is found that purely elastic instability occurs in most depth ratios for the whole spectrum of waves when the fluid with elasticity is placed as the inner layer next to the solid wall. In the study of stability for viscoelastic fluids it demonstrates that arranging the more elastic and less viscous fluid as the outer layer leads to interfacial stability. In the more than three-layers investigation we found that placing the most viscous and least elastic liquid as the innermost layer next to the solid wall and the least viscous and most elastic liquid as the outermost layer next to the passive air can ensure the stability for the whole spectrum of waves.
Analysis of Shrinkage Development of Injection Moulded PS Samples
Authors: Pantani R. , Titomanlio G. 
Published: December 2013

Abstract
Modern approaches to the phenomenon of dimensional accuracy in injection moulding link the evolution of shrinkage from the moment of first solidification to a force balance between restraining and constraining forces which sets in inside the mould before ejection. Such an approach needs a complete understanding of what happens inside the cavity during the moulding cycle. In a recent paper [9], a new technique has been presented, by which it is possible to follow the shrinkage development of an injection moulded sample from the moment it starts solidifying to soon after ejection.
In this work, with reference to a simple rectangular cavity, shrinkage curves measured by strain gages in different moulding conditions are analysed by means of a simple thermomechanical model recently proposed. Results show that the model satisfactorily predicts the moment shrinkage starts inside the mould and reveal the existence of a restraining force not due to pressure, which builds in gradually in a few seconds from the instant of first solidification. Knowing the value of this force—which can be drawn by Hooke's law from the strain jump at mould opening—the model gives a good description of both shrinkage development inside the mould and ejection shrinkage.
Chrome Nitride Coatings for Applications in Plastics Processing
Authors: Berg G. , Friedrich C. , Broszeit E. , Cremer M. 
Published: December 2013

Abstract
Coated moulds, especially cavity surfaces and ejection parts are state of the art in plastics processing. Regarding the plastification unit i.e. screws and barrels coatings are not well established. Wear in processing remains a problem, especially when no abrasion is permitted e.g. in manufacturing optical elements. The surfaces must resist the abrasion of hard glas fibres as well as the corrosive attack of the polymers. Electroplated chrome is one of the answers to these demands, because of its hardness and corrosion resistance. Another solution are thin hard coatings which are not yet well established. Titanium nitride produced by PVD technique was found to show excellent abrasion resistance but often not sufficient corrosion properties. Chrome nitride was found to have great hardness like TiN, corrosion resistance behaviour similar to electroplated chrome and in contrast to electroplated coatings no tensile internal stress.
The present study deals with the spectrum of characteristic properties of CrxN coatings like hardness, adhesion, internal stress, chemical composition and phases produced by PVD magnetron sputtering. The coatings were deposited on steel, described in characteristics and tested in a model wear test with plasticized moulding material (PA 66-GF50 and others) simulating the tribological situation between screw and barrel of extruders or injection moulds. The tribological behaviour was studied after the complex test procedure. The high temperature of the plasticized material, high abrasion by glas fibres and corrosive influence could only change the coatings properties of CrxN slightly.
Simulation of Flow in an Intermeshing Modular Counter-rotating Twin Screw Extruder: Non-Newtonian and Non-Isothermal Behavior
Authors: Hong M. H. , White J. L. 
Published: December 2013

Abstract
An analysis of flow fields, pressure fields and screw pumping characteristics is presented for non-Newtonian fluids in various types of screw elements of an intermeshing counter-rotating twin screw extruder. These elements are in turn considered modules of a modular intermeshing counter-rotating twin screw extruder and an analysis of non-isothermal starved low in such a machine is presented. Pressure profiles, fill factor profiles and temperature profiles have been calculated for various modular screw designs of a Leistritz GG modular intermeshing counter-rotating twin screw extruder.