bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mixing and Extrusion of High Silica and all Silica-natural Rubber Compounds
Authors: Nakajima N. , Shieh W. J. , Wang Z. G. 
Published: December 2013

Abstract
This work is an investigation on causes of extrusion problem of a high silica- and all silica-filled natural rubber compounds containing a coupling agent. The 67% silica and 33% carbon black, N110 compound (Compound 3) gave a wavy surface of extrudate from a profile die. The 100% silica-filled compound (Compound 4) was too stiff to be extruded. Reference compounds, 100% carbon black (Compound 1) and 33% silica with 67% carbon black (Compound 2), gave smooth extrudates. The amplitude dependence of storage modulus measurements indicated Compound 4 had a poorer dispersion of the filler. Scanning electron microscopy also showed a poorer dispersion for this compound. However, Compound 3 could not be distinguished from Compounds 1 and 2 in the above investigation. Transient shear measurements at very low deformation rate indicated a reaction between natural rubber and the coupling agent, resulting in gel and long-branch formation. Differential scanning calorimetry indicated the coupling reaction was completed at 140°C within the mixing time. By holding the maximum temperature of mixing as low as possible, the extrudate of Compound 3 became smooth, but Compound 4 still did not perform well. Improvement of dispersion is necessary to make Compound 4 extrudable.
An Analytical Model of Partial and Thorough Melting in Single-screw Extruders
Authors: Potente H. 
Published: December 2013

Abstract
Based on the classic Tadmor model, a number of mathematical models have been developed for calculating the melting profile in single-screw machines. The most comprehensive of these is the five-zone model from Lindt. All these models can only be solved by numerical methods. Parallel to this, attempts have been made to find analytical solutions which describe the melting profile with sufficient accuracy. In this report a comprehensive analytical solution for the whole premelting- and melting process on barrel and screw with respect to the power law will be given.
Extrusion of Rubber Compounds and Highly Filled Thermoplastics through Coathanger Dies
Authors: Wang Y. 
Published: December 2013

Abstract
The isothermal flow of plastic fluids in coathanger dies is studied. A general three-dimensional finite element code is developed for the flow analysis purpose. The pressure distribution, the velocity distribution and the transverse flow rate distribution are calculated. The yield value of filled compounds gives rise to a mobile plug in the flow channel. The development of plug zone along the flow direction is also shown by the finite element analysis. The effect of the die geometry on the transverse flow rate distribution is critically discussed. It is found that the cross sections of the flow channel in a coathanger die has the shape of a dog bone or a dumbell which make a nearly even transverse flow rate distribution possible.
Conveying and Melting in Screw Extruders with Axial Screw Movement
Authors: Rauwendaal C. 
Published: December 2013

Abstract
Reciprocating extruders are used in injection molding. The number of reciprocating extruders used in the plastics processing industry is larger than conventional extruders. Therefore it is surprising that only few studies have been made of the conveying and melting process in reciprocating extruders.
Melt Strength Behavior of Polyethylene Blends**
Authors: Ghijsels A. , Ente J. J. S. M. , Raadsen J. 
Published: December 2013

Abstract
Melt strength data are presented on different types of binary polyethylene blends as linear low density polyethylene/low density polyethylene (LLDPE/LDPE), linear low density polyethylene/high density polyethylene (LLDPE/HDPE) and LDPE/LDPE. Melt strength was assessed from uniaxial tensile experiments with a Rheotens apparatus. In addition, the blends were characterised in terms of a few other rheological properties such as the zero-shear viscosity and the extrudate swell in capillary extrusion. For the LLDPE/LDPE blend pairs synergistic effects were observed for the melt strength and some other properties. No melt strength synergism was observed for the LLDPE/HDPE and the LDPE/ LDPE blends. The results are discussed in terms of the Bersted model on the effects of long chain branching on the low-shear melt viscosity of polyethylenes.
Thermoviscoelastic Calculation of Residual Stresses and Residual Shapes of Injection Molded Parts**
Authors: Kabanemi K. K. , Crochet M. J. 
Published: December 2013

Abstract
The present paper describes a three-dimensional finite element method for calculating thermoviscoelastic stresses generated during cooling of injection molded parts. The initial temperature field corresponds to the end of the filling stage. The fully time-dependent algorithm is based on the calculation of the elastic response at every time step. The time-temperature equivalence is assumed for the non-isothermal behavior. At the end of the calculation, one obtains the residual stresses and the shape of molded parts at room temperature. The method is illustrated by means of four examples.
Analysis and Simulation of Structural Reaction Injection Molding (SRIM)
Authors: Aoyagi H. , Uenoyama M. , Güçeri S. I. 
Published: December 2013

Abstract
A numerical approach is taken to the analysis and simulation of structural reaction injection molding (SRIM). Formulation is based on anisotropic Darcy flow through a porous medium. Governing equations are developed for thin gap mold cavities with no gapwise flow. The reaction of the resin and its effect on the local viscosity are accounted for by using constitutive models. A numerical grid generation method is employed to handle irregularly shaped flow domains during the filling stage. A new finite difference mesh is generated at each time step to cover the flow domain as described by the mold boundaries and the moving resin front. The technique is shown to be capable of handling a wide range of irregularly shaped planar geometries in monitoring the instantaneous state of the cure along with the temperature and the flow fields in a detailed form. The results indicate a highly pronounced disturbance of the temperature field due to the exothermic nature of the chemical reaction. It is also shown that this temperature field and the state of cure significantly influence the flow field through fluid viscosity. The method reduces to the simulation of resin transfer molding (RTM) processes by dropping the reaction terms. The comparisons with limited experimental data for isothermal flows indicate high accuracy in both predicting the resin front locations and the fill pressures.
Starve-fed Flow in Co-Rotating Twin Screw Extruders
Authors: Bigio D. , Cassidy K. , Dellapa M. , Baim W. 
Published: December 2013

Abstract
A visual study was performed to determine the mixing abilities in simple conveying sections of the partially-filled, corotating, twin screw extruders (PFCoTSE). The amount of mixing that occurs in the PFCoTSE is heavily dependent on the degree to which the channels are filled. A quasi-quantitative method of measuring the growth of an injected tracer is used in determining mixing. It was determined that the PFCoTSE's mixing sections are linear mixers as can be seen from the fact that an injection of tracer quickly transforms into a line and stays as a line throughout the machine and does not break apart while going through the nip (i.e., no reorientation).
Modelling Twin Rotor Mixers and Extruders
Authors: David B. , Sapir T. , Nir A. , Tadmor Z. 
Published: December 2013

Abstract
An improved flow model for simulating flow in batch and continuous twin rotor mixers and extruders is presented. The model adopts an Eulerian point of view from the stationary barrel surface. It incorporates Couette flow analysis, which accounts for the curvature effects in the non-intermeshing region, and correction factors for treatment of flow near the bounding sidewalls of a batch mixer. A method for tracking the motion of fluid particles is presented.
Real Time Video Techniques in the Analysis of Blown Film Instability
Authors: Sweeney P. A. , Campbell G. A. , Feeney F. A. 
Published: December 2013

Abstract
This paper describes a device which was developed to measure the degree of instability during blown film processing. Two types of data analysis are developed which can be used to analyze the instability data and the relative merits of each are discussed. The paper also describes how the device was used to measure the effect of adding two stabilizers (2 MI LDPE and 0.25 MI LDPE) at different concentrations to a 1 MI LLDPE during blown film processing. The process stability improved with higher concentrations of either LDPE with the 0.25 MI LDPE having the stronger effect. These results are consistent with the belief that long chain branching in polyethylenes plays a major role in stabilizing the blown film processing of polyethylenes.
Injection Molding of iPP
Authors: Saiu M. , Brucato V. , Piccarolo S. , Titomanlio G. 
Published: December 2013

Abstract
An experimental study of iPP injection molding is carried out. Pressure distribution during both filling and post filling stages, mass entering the mold during each stage of the process, morphology and crystallinity distribution of the final object are analysed. Interesting features are evidenced and discussed in relation to gate geometry and filling flow rate. Evidence of flow crystallization inside the cavity is also reported.
The Challenges of Waste Toward the 21st Century
Authors: Saeki Y. 
Published: December 2013

Abstract
The problems of waste disposal have become major issues in Japan. Japan must deal directly with these issues. In early 1970s, “KOGAI” or environmental pollution already loomed as major problems. A number of technical innovations and systems were proposed to recycle various waste products. Based on those experiences, current situation of urban refuse, waste plastics, scrapped tires and scrapped automobiles in Japan and their challenges toward 21st century are discussed.
Effect of Surface Coatings on Wall Slip of LLDPE
Authors: Hatzikiriakos S. G. , Stewart C. W. , Dealy J. M. 
Published: December 2013

Abstract
The polymer-metal interface in a sliding plate rheometer was modified by applying three fluoropolymer coatings to the plates in order to examine their effect on the wall slip behavior of a linear low density polyethylene. All three coating materials increased the slip velocity markedly. Furthermore, it was found that the critical shear stress for the onset of slip scales well with the work of adhesion of the interface, suggesting that slip is the result of adhesive failure at the interface.
Effects of Interfacial Conditions on Wall Slip and Sharkskin Melt Fracture of HDPE
Authors: Hatzikiriakos S. G. , Dealy J. M. 
Published: December 2013

Abstract
Experiments were performed in capillary and slit rheometers to determine the effects of the presence of fluoropolymers at the polymer-wall interface on wall slip and extrudate distortion of a molten high density polyethylene. Two fluoropolymers were used to modify the interface. It was found that one of these decreased slip compared to the clean interface while the other increased slip. However, both were found to improve extrudate appearance, thus indicating that both adhesion promoters and slip promoters may improve extrudate appearance. The mechanism underlying this rather surprising conclusion is also discussed.
Modeling of Non-isothermal Film Blowing with Integral Constitutive Equations
Authors: Alaie S. M. , Papanastasiou T. C. 
Published: December 2013

Abstract
Non-isothermal, melt film-blowing is analysed by means of a nonlinear integral constitutive equation that incorporates shear history effects, spectrum of relaxation times, shear thinning and extension thinning or thickening. The temperature history, as predicted by the simultaneously solved energy equation, is introduced into the constitutive equation by means of the appropriate shift factor incorporated in the linear modulus of the constitutive equation. The resulting system of integrodifferential equations is solved by finite element discretization and Newton iteration. Bubble shape, velocity, temperature, stress and thickness profiles are predicted simultaneously. Predicted film thickness, temperature and stress profiles of blowing of polystyrene are compared with experimental data taken from the literature.
Processing-Structure-Properties Relationships in Blends with Thermotropic Liquid Crystalline Polymers
Authors: Incarnato L. , Nobile M. R. , Frigione M. , Motta O. , Acierno D. 
Published: December 2013

Abstract
In this paper the effect of the inclusion of thermotropic liquid crystalline polymers (TLCP) in thermoplastic polymers is analyzed, with due attention to similar studies reported in the literature. Numerous results relative to TLCP containing blends are considered in terms of structure development in typical processing operations like extrusion and fiber spinning. Several systems have been studied in order to emphasize that different effects can be obtained as regards processing and mechanical properties of the host matrices. As for rheological aspects, it has been verified that TLCP can be considered as effective flow aids, even at low concentrations. The addition of a low percentage (5 to 10 %) of a TLCP with a viscosity lower than that of the matrix produces a significant reduction (25 to 40 %) in the blend viscosity. Moreover, mechanical results have shown that an improvement of the matrix rigidity can be obtained, especially at high percentages of TLCP (30 %), under processing conditions where a highly extensional flow prevails. However, a decrease in the ultimate elongation of the matrices has been found in all systems where a poor adhesion between the two phases exists.
RIM-pultruded Prepreg for the Injection Molding of Long-fiber Epoxy Composites
Authors: Ishida H. , Zimmerman D. A. 
Published: December 2013

Abstract
A long-fiber injection molded phenoxy composite has been developed by using a new processing technique that combines reaction injection molding (RIM) and pultrusion to produce a prepreg pellet. RIM-pultrusion uses a reaction injection system instead of the resin bath typically used in pultrusion. The resin system and process developments are described. The fiber damage during injection molding is minimized by using the RIM-pultruded pellet as prepreg. The resulting long-fiber carbon fiber composite has an average volume aspect ratio that is an order of magnitude higher compared to typical short-fiber injection molding. The fiber length distribution (FLD) is measured for both glass and carbon composites. The extent of bundling has been determined from the moment ratio. The extent of reaction of the diepoxide during processing is measured using Fourier transform infrared spectroscopy (FT-IR). The pultrusion line speed and temperature are determined for secondary processing, namely injection molding, from the epoxide conversion. Also, dynamic mechanical analysis has been performed on the resin, prepreg, and injection molded sample to study the mechanical and thermal properties. Scanning electron microscopy is employed to examine fiber-matrix adhesion, void content, bundling, and fiber pull-out.
Potential Applications for Computer-aided Extruder Design
Authors: Potente H. , Hanhart W. , Schöppner V. 
Published: December 2013

Abstract
The simulation method is able to relieve the engineer of experimental work during the planning of extrusion plant and thus clearly reduces the development time. Sufficiently precise determination of the calculable parameters is possible with the process models developed so far. The empirical knowledge of the engineer is, of course, necessary as well in order to estimate the impact of influencing parameters that are not taken into account in the calculation models. The presented simulation program REX can perform these complex calculations in a comprehensive manner, with its simple and comfortable user interface. The program, however, can be employed as a valuable tool only if it is in the hands of an expert operator who can, and indeed must, be able to interpret the results as well.
Real-time Neutron Radiography of Injection Mold Filling
Authors: Weissenberger M. M. , Giacomin A. J. , Reuscher J. A. , Russell C. M. 
Published: December 2013

Abstract
A new method of flow visualization has been used to film the injection mold filling operation. A study of jetting has been performed using real-time neutron radiography which permits real-time visualization through metal molds. Results of this method for a thermoplastic elastomer filling an end-gated strip mold are reported for a bench-scale injection molder at constant pressure.
Unsteady Flow of Semi-Concentrated Fiber Suspensions in Compression Molding
Authors: Ahmed A. , Alexandrou A. N. 
Published: December 2013

Abstract
This paper deals with the flow behavior and the resulting fiber orientation during compression molding of semi-concentrated fiber suspensions. The suspension is characterized using the Dinh and Armstrong integral constitutive relations, expressed in terms of the finite deformation tensors. The equations of motion are expressed in a convenient Generalized Eulerian-Lagrangian reference frame. The resulting nonlinear system of equations is solved using full Newton-Raphson iteration procedure. An integral boundary condition has been applied at the press wall to represent the constant force condition at that boundary. Results are presented for the isothermal filling of a two-dimensional rectangular cavity for the flow field and the associated fiber orientation. The influence of different parameters such as molding force, fiber concentration, fiber aspect ratio etc. on the compression rate is also presented.
Residual Stresses in Quenched and Injection Moulded Products
Authors: Jansen K. M. B. 
Published: December 2013

Abstract
The differences between residual stress formation mechanisms are studied for several important polymer processes. The most important cases are free quenching (e.g. in extrusion), constrained quenching and constrained quenching with varying applied pressure (injection moulding). A simple, but physically relevant, elastic solid model is assumed (viscous melt and purely elastic solid) yielding Struik's cooling stress model for the free quenching case. In the constrained quenching case, however, the residual stresses are found to vanish. This allowed us to derive a simple analytical expression for the residual stresses in injection moulded products. These stresses were found to be proportional to the maximum melt pressure and are tensile near the surfaces. The predictions compared well with the measured stress distribution. Finally the effects of residual stresses with respect to warpage and environmental stress cracking are discussed.
Influence of the Thermomechanical Parameters on the Morphology of a Polyamide (PA 6) and Polypropylene Blend
Authors: Knobel B. , Villemaire J. P. , Agassant J. F. 
Published: December 2013

Abstract
The morphology of a polypropylene and polyamide blend has been investigated with the Rheoplast rheometer which allows us to apply a well defined thermomechanical history before the capillary flow. The polymer flow in the Rheoplast has been modeled using a homogenization hypothesis for the rheology. Correlations between the different observed morphologies and shear rates, elongational rates as well as dissipated energies are discussed.
Finite Element Simulation of Thick Tube Expansions
Authors: Sun J. , Luo X.-L. , Tanner R. I. 
Published: December 2013

Abstract
We consider the numerical simulation of the combined drawing and radial expansion of a thick tube, which is a possible model for continuous tube-making. Both Newtonian and visco-elastic cases are considered. Mesh refinement studies show convergence; to stabilize the computations we have introduced relaxation factors. The main difficulty here is in finding the region of contact with the sizing die, as well as the form of the free surface. It was found that the extra stress component, τθθ, is most helpful in considering the characteristics of tube expansion. The maximum value of τθθ occurs near the outer wall of the exit of the annular die for Newtonian flow and near the interface for K-BKZ liquids. Both for Newtonian and K-BKZ liquids the extra stress component τθθ in the expansion region, not including the vicinity of the exit of the die, develops from the inner free surface toward the outer free surface. The pressure value needed for tube expansion increases and then decreases as the expansion ratio R0/RW increases.
Flexural Modulus of Compression Molded Glass Fiber Reinforced Thermoplastics
Authors: Xia M. , Hamada H. , Maekawa Z. 
Published: December 2013

Abstract
The flexural properties of compression molded stampable glass fiber reinforced polypropylene are examined. Fibers flowing with the polymeric matrix are found to be oriented close to the edge of the die. The fiber orientation distribution is characterized by a fiber orientation index using an image processing system. The flexural elastic modulus of the plaque estimated from laminated-plate theory is found to be in good agreement with the experimental results.
Multilayer Injection Moulding
Authors: Peters G. W. M. , van der Velden P. J. L. , Meijer H. E. H. , Schoone P. 
Published: December 2013

Abstract
The modelling of multilayer reactive injection moulding is studied. After presenting the equations describing the process, two important aspects are dealt with in more detail. These are particle tracking and the modelling of the flow front. First results demonstrate the possibilities of the modelling and show satisfactory agreement between predictions of numerical simulations and experimental results, concerning particle tracking in the whole flow domain and the break-through of layers in sequential two component moulding.
Modeling and Simulation of High Reynolds' Number Flows During Reaction Injection Mold Filling
Authors: Mohammed Rahima K. , Osswald Tim A. , Spiegelhoff Timothy J. , Sun Esther M. 
Published: December 2013

Abstract
Reaction injection molding (RIM) involves the injection of low viscosity polymers into mold cavities at relatively high injection speeds. The short cycle times, coupled with low injection pressures and clamping forces make RIM well suited for the rapid production of complex parts. High injection speeds, low viscosities and narrow cavities lead to high Reynolds' number flows during mold filling. The presence of high Reynolds' number flows is a notable difference between RIM and conventional thermoplastic injection molding (TIM). Unfortunately, this type of flow with significant inertia effects can lead to reduced part quality. The material properties and characteristics of RIM parts are influenced by flow patterns, weld lines, air entrapment as bubbles or pockets, especially as the material flows around inserts. These defects and characteristics, coupled with a growing demand for high quality RIM parts, is responsible for the increased interest in the flow during mold filling. This paper presents the development and test of a model to stimulate high Reynolds' number flows in thin cavities present during reaction injection mold filling.