bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of the Inter-Relationships Between Processing Conditions and Properties of an Injection Molded Silicone Ring Using an Experimental Design
Authors: Barbaroux M. , Stalet G. , Regnier G. , Trotignon J.-P. 
Published: December 2013

Abstract
The effects of injection-molding parameters on the mechanical-physical properties of a liquid silicone rubber (LSR) injection-molded ring were studied through an experimental design. The effects of the changeover point (volume or pressure driven), runner (hot or cold), hold pressure, mold temperature and injection flow rate variations were evaluated based upon the responses related to both material properties (ultimate elongation and tensile stress in a tensile test, swelling in hexane, hardness, density) and ring properties (cross sectional diameter, weight, volume). It was determined that ring density is not dependent on the parameters studied. The mold temperature appeared to be a very influential parameter, especially concerning material characteristics: it affects the swelling ratio, hardness, and ultimate properties, but weight and volume are only affected when the cold runner is used. The hold pressure has an effect on both the weight and volume of the ring. The type of changeover used (volume or pressure) has no effect when a cold runner is used, but affects the weight, volume, and ultimate properties of the ring, when a hot runner is used. The injection flow rate did not affect the observed characteristics.
Numerical Simulation of the Flow and Fiber Orientation in Reinforced Thermoplastic Injection Molded Products
Authors: Kabanemi K. K. , Hétu J. F. , Garcia-Rejon A. 
Published: December 2013

Abstract
This paper describes a fully three-dimensional transient finite element method for calculating the flow behavior and fiber orientation during filling of injection molded parts. The fiber-fiber interaction is taken into account. The momentum and continuity equations are first solved with the viscoelastic stress treated as a fixed body force. The kinetic equation for the orientation tensor is then integrated with known kinematics using the standard Galerkin method. The calculation is performed on a time-dependent flow domain. Since the method is truly three-dimensional, singular regions such as the flow front or near injection gates and solid boundaries, where decoupled approximations are not valid, are naturally dealt with. The material anisotropy behavior is modeled by using the Doi-Doraiswamy-Metzner model. Numerical results, involving the Poiseuille flow and the filling of an end-gated plate, emphasizing the importance of the three-dimensional coupling calculations between the flow and orientation are presented.
Comparison between LDPE Conventional and Autothermal Extrusion Characteristics
Authors: Sikora J. W. 
Published: December 2013

Abstract
In the paper, a characterization of autothermal and conventional extrusion processes of low density polyethylene (LDPE) in the typical single screw extruder equipped with a classical screw was presented. It was shown that autothermal (adiabatic) extrusion process is characterized by better effectivity factors than a conventional extrusion process carried out in the same basic extrusion conditions. In both processes the mass flow rate, total extruder power, total energy consumption per unit mass, extruder energy efficiency, extrusion velocity, temperature distribution along the plasticating system and extruder head, were compared. The attempt to present shear stress and flow rate distribution during laminar and isothermal flow of the non-Newtonian fluid through the circular channel (extrusion die) was undertaken. Appropriate dependences of experimental factors on the rotational speed and angular frequency of the screw were made. Appropriate conclusions were drawn.
Comparative Study of Structure Development in Melt Spinning Polyolefin Fibers
Authors: Choi C.-H. , White J. L. 
Published: December 2013

Abstract
A comparative study of crystallization and orientation development in melt spinning is presented for four polyolefins: high density polyethylene (PE), polypropylene (PP), polybutylene (PB-1), and poly-4-methylpentene-1 (P4MP). The purpose was to compare the behavior of two relatively unknown polyolefins PB-1 and P4MP with the much better known and characterized PE and PP. Melt spinning was carried out at different temperatures. Melt spun filaments were characterized by wide angle x-ray diffraction (WAXS), birefringence and differential scanning calorimetry (DSC) measurements. Polymorphism (multiple crystalline states) is noted in the filaments of polybutylene which exhibits aging from one form to another as well as in polypropylene. Careful attention is given to heat transfer during cooling. The orientation of flexible chains in the melt state is well known to be determined by the stress field. The crystalline orientation of the solidified crystalline filaments as a function of spinline stress is found by WAXS to be highest for the P4MP and lowest for the PE. Birefringences of the melt spun PE fiber are however higher than PP or PB-1 and P4MP which had the lowest values when comparisons are made at the same spinline stress. However if intrinsic birefringence was used, the data order the same as the WAXS results.
Experimental Validation of Shrinkage Predictions for Injection Molded Products
Authors: Jansen K.M.B. , van Dijk D.J. , Burgers E.V. 
Published: December 2013

Abstract
Two injection moulding simulation codes (C-MOLD of AC Technology and VIp of Eindhoven University) are compared with experimental results regarding cavity pressure and product shrinkage. It turns out that the cavity pressure profiles are only moderately well predicted by both codes. The shrinkage predictions can be considered as a post processing step with temperature and pressure fields as an input (the so-called thermoelastic model). It is shown that the shrinkage predictions agree well with the measurements using the thermoelastic model with actual pressure profiles as an input. Direct simulation of product shrinkages resulted in an overprediction of shrinkage.
Peroxide Induced Crosslinking and Degradation of PA
Authors: Yu Q. , Zhu S. 
Published: December 2013

Abstract
Peroxide induced crosslinking and degradation of nylon-12 were experimentally investigated using an on-line electron spin resonance (ESR) spectrometer. It was found that different types of polymer radicals were involved in various peroxide modification processes. Five-line ESR spectra were observed in the DCP/nylon-12 and TBPB/nylon-12 systems, while the L130/nylon-12 system gave a three-line spectrum initially, followed by a transition to a single line. Based on the radical information, as well as gelation and viscosity measurements, various reaction mechanisms were proposed depending on the type of peroxide. TBPB is in favor of the degradation of nylon-12, while DCP and L130 promote crosslinking of the polymer. The gel formation was followed to facilitate the study of crosslinking kinetics. The initial gelation rate increased linearly with the peroxide concentration and/or temperature. The formation of crosslinked network impeded the crystallization of nylon-12 and reduced the degree of crystallinity. The high crosslinking extent resulted in low melting temperature and heat.
Squalane as Model for Free Radical Reactivity of PP
Authors: Drillières S. , Mestanza R. , Graebling D. 
Published: December 2013

Abstract
The degradation, grafting and crosslinking of polypropylene have been studied with a free modelling system: the squalane. This study used conditions similar to reactive extrusion in terms of temperature and concentration of actives species. The products of reactions were characterized by mass spectrometry and IR spectroscopy. The reaction between peroxide and squalane confirms the importance of the half-life of the peroxide in limiting the degradation of the squalane chain. In presence of monomer, we observed simultaneously grafting and β-scission of squalane. Comparison between methacrylates and acrylates shows that acrylates are much more effective for grafting than methacrylates. With trifunctional monomers, the main reaction is the crosslinking of squalane (or recombination of macroradicals via the monomer). In this case, triacrylates were also more effective.
Using Mold Pressure Rise Data to Obtain Viscosity of Fast Polymerizing Systems
Authors: Kim D. S. , Garcia M. A. , Macosko C. W. 
Published: December 2013

Abstract
Typical reaction injection molding oligomers gel in less than 5 s, making it very difficult to measure their viscosity rise in a rheometer. The parameters of the viscosity function for two thermoset polyurethane (PU) systems made from modified 4,4'-diphenylmethane diisocyanates and polyether polyols were obtained through nonlinear regression of a mold filling simulation model using pressure rise data. The pressure rises were measured at the inlet point of an end gated rectangular mold. Adiabatic temperature rise experiments were carried out to obtain reaction kinetic equations of the PU systems. A second order Arrhenius type reaction kinetic equation described the adiabatic temperature data well. Viscosity change of a low catalyst PU system during isothermal polymerization was measured using a parallel plate rheometer, and a viscosity function was estimated from these data and the kinetic data. The viscosity function determined through regression of pressure rise data using the mold filling simulation model compared reasonably well to the viscosity function obtained from the rheometer data.
Effect of Temperature and Compatibilizer on Interfacial Tension of PE/PA-6 and PP/EVOH
Authors: Garmabi H. , Demarquette N. R. , Kamal M. R. 
Published: December 2013

Abstract
Interfacial tension measurements for polyethylene/polyamide-6 (PE/PA-6) and polypropylene/ethylene-vinyl alcohol copolymer (PP/EVOH) pairs were performed using the spinning drop method. The effects of the temperature and maleation content of the polyolefin on the interfacial tension were evaluated. The temperature coefficients of interfacial tension were found to be 0.036 and 0.087 dyne/cm/°C for the PE/PA-6 and maleated PP/EVOH systems, respectively. The interfacial tension of PE/PA-6 system showed exponential dependence on the maleation content of PE. The accuracy of the spinning drop method was evaluated against the pendant drop technique. It was found that the spinning drop technique tends to yield lower interfacial tension values than the pendant drop method. The harmonicmean equation was found to provide a fair estimate for the interfacial tension of PE/PA-6 pair.
Pseudoplasticity and Dilatancy in Shallow Channel Flows
Authors: Lindt J. T. 
Published: December 2013

Abstract
A novel formulation is presented applicable to flows of inelastic, shear-thinning and shear-thickening, fluids between parallel plates. The solution is documented by comprehensive contour maps allowing flow descriptions to be reconstructed for the Ostwald-deWaele and the Cross-/Carreau fluid model fluids within an exhaustive range of rheological and flow parameters, 0 < n ≤ 2 and 0 ≤ q ≤ 2. The description of pseudoplastic behavior is extended to values approaching zero, numerical stability permitting (0.01 ≤ n < 1). The paper highlights the dilatant behavior, 1 ≤ n ≤ 2, reported previously to arise in certain heterogeneous systems, and shown to affect significantly other types of non-Newtonian flows. It is suggested that in thermally and compositionally developing flows, typical of reactive processing, where dilatancy may arise, the present formulation can facilitate solutions to the coupled rheological and heat/mass transfer problems encountered. The newly generated data on dilatant liquids suggest a dramatic increase in energy dissipation with the increasing degree of dilatancy.
Development of High Quality LLDPE and Optimised Processing for Film Blowing
Authors: Debbaut B. , Goublomme A. , Homerin O. , Koopmans R. , Liebman D. , Meissner J. , Schroeter B. , Reckmann B. , Daponte T. , Verschaeren P. , Agassant J.-F. , Vergnes B. , Venet C. 
Published: December 2013

Abstract
The majority of LLDPE resins is processed via blown film extrusion techniques for various applications in the industrial and consumer packaging business. These LLDPE resins all have, independent of the molecular structure differences, the same intrinsic limitation in blown film extrusion processing. These limitations are: low output, high sensitivity to surface defects (stripes, sharkskin), high machine power requirement, need for large die gaps, lower bubble stability, and low melt strength. As a consequence, the more versatile—manufacturing and property wise—LLDPE resins are not used to their full potential. The industrial objective is therefore threefold:

•
develop a new LLDPE resin overcoming the above limitations,

•
develop a new flexible blown film extrusion line tailored to the new generation of LLDPE resins,

•
develop an efficient 3-D finite element simulation code to assist in the resin and blown film extrusion line development.
Structure and Properties of Injection Moldings of β-Crystal Nucleator-added PP
Authors: Fujiyama M. 
Published: December 2013

Abstract
A homo isotactic polypropylene (PP) and random and block PP copolymers with ethylene were added with 0 to 10 ppm of γ-quinacridone which is a β-crystal nucleator of PP. Flexural and Izod impact test specimens were injection-molded from the PPs at cylinder temperatures of 200 to 320°C and the structure and properties have been studied. 1) Although the β-crystal content of the block PP is nearly the same as that of the homo PP, the β-crystal content of the random PP is largely lower than that of the homo PP. 2) The Izod impact strength is increased by the addition of γ-quinacridone. The increase is high for the homo and block PPs and very low for the random PP. There are cases where the Izod impact strength is increased by more than four folds for the block PP. 3) The flexural modulus and strength are decreased by the addition of γ-quinacridone and the decreases of the random PP are lower than those of the homo and block PPs. From above, it may be said that the modification effect of PP by the addition of γ-quinacridone is prominent for the homo and block PPs in which the β-crystal is ease to form and the effect is weak for the random PP in which the β-crystal is difficult to form.
Thermal Effects in the Numerical Simulation of the Thermoforming of Multilayered Polymer Sheets
Authors: Bellet M. , Vantal M.-H. , Monasse B. 
Published: December 2013

Abstract
This paper mainly treats the thermal effects during the thermoforming process while most of the previous analyses consider an isothermal deformation. A non isothermal three dimensional finite element model of the thermoforming process is proposed. It couples the thermal equations in the thickness and mechanical equations on the mean surface of the sheet. The mechanical resolution is done by a finite element method using a membrane approximation. The deformation is driven by a pressure difference through the sheet. The thermal resolution uses a one dimension finite element method in the thickness with convection or conduction at the surface and dissipation of mechanical energy. The polymer cooling is very efficient during the contact with the tools. The coupling is done by the thermal dependent rheology. The respective contributions of friction and thermal effects in the thickness of the part during the process are discussed. The model also considers a possible multilayered material, with specific rheological parameters inside each layer. The rheology of a polystyrene was measured under elongation as a function of temperature, strain and strain-rate and described by a viscoplastic law. The predictions of the model were compared with measurements on an instrumented thermoforming machine and with the local thickness of axisymmetrical parts and with 3-D parts thermoformed with the same polystyrene.
Measurement and Prediction of Anisotropy in Injection Moulded PP Products
Authors: Jansen K. M. B. 
Published: December 2013

Abstract
Exact knowledge of anisotropy in thermal and mechanical properties of moulded articles is important since it is directly related to undesired phenomena like warpage. In this study careful measurements of the coefficients of thermal expansion, elastic moduli, Poisson constants and linear compressibilities showed that the anisotropy of these properties was about 10%, for injection moulded polypropylene plates. A simple composite model was proposed which could predict all thermal and mechanical properties mentioned above from data of the amorphous and crystalline phases. The degree of crystallization, skin thickness and average orientation of the fibrillar precursors are the main input parameters. It turned out that although individual values were slightly over or underpredicted, the amount of anisotropy was usually predicted correctly. The only prediction which disagreed with the measurements was that of the coefficient of thermal expansion, which was measured to be larger in flow direction than in width direction.
The changes of shrinkage and shrinkage anisotropy along the flowpath were studied experimentally for different processing conditions. The most remarkable observations were that variations in injection velocity only affected width shrinkage, while melt and mould temperatures specifically acted on length shrinkage. Holding pressure, on the other hand, affected both length and width shrinkage with the same amount.
Gas Penetrations in Symmetrical Tapping Ribs during Gas-Assisted Injection Molding
Authors: Parng S. H. , Yang S. Y. 
Published: December 2013

Abstract
The system of gas penetrations through melt at symmetrical rib channels is found unstable. By varying cross-sectional area of gas channel along the flow length, this research is devoted to observing the effect of the gas penetrations system in tapering symmetrical ribs during gas-assisted injection molding. With decreasing the cross section along the flow length and decelerate the penetration of gas-tip fronts, the degree of uneven gas penetrations can be reduced and stability is improved.
Flow Analysis in Screw Extruders-Effect of Kinematic Conditions
Authors: Rauwendaal C. , Osswald T. A. , Tellez G. , Gramann P.J. 
Published: December 2013

Abstract
Recently, several investigators have challenged the simplifying assumption of using a stationary screw with a rotating barrel when analyzing the flow in single screw extruders. The investigators claim that there are significant differences between the realistic and simplified cases, such as a 12 percent difference in throughput [1]. This paper presents an analytical derivation for the flow in a laid out system and one which includes the curvature of the screw. An experimental set-up was built which allows the rotation of the barrel with a stationary screw and the rotation of the screw with a stationary barrel, and a three dimensional flow simulation program was used to model the flow in the extruder using the two conditions. The analytical, experimental and numerical analyses show that it is justified to use the stationary screw assumption when modeling the flow in single screw extruders.
Distributive Mixing in an Axial Discharge Continous Mixer
Authors: Yao C.-H. , Manas-Zloczower I. 
Published: December 2013

Abstract
The axial discharge continuous mixer-LCMAX 40, which combines the features of a continuous mixer and the co-rotating twin screw extruder, was analyzed in this work for its distributive mixing efficiency. We analyzed the distributive mixing performance for various rotor configurations. Four designs with either alternating or block arrangements of pushing and counter-pushing units were investigated. A fluid dynamics analysis package-FIDAP, based on the finite element method was used to model the flow behavior of a power law model fluid. Distributive mixing was quantified using particle distributions along the axial distance. Residence time distribution (RTD) functions were calculated and found to reveal interesting information related to design features. The influence of design on the evolution of the particle path length and shear strain distribution was also discussed. The counter-pushing units and their arrangements were found to play an important role in distributive mixing.
Manufacture-Induced Inaccuracies of Spinning Dies1
Authors: Beyreuther R. , Brünig H. , Hofmann H. 
Published: December 2013

Abstract
The die in the melt spinning process distributes the whole melt stream into individual small melt streams that pass the die parallel to each other. The number of holes in the die determines the number of filaments in the spun fiber bundle. As the whole melt stream (i. e. the total throughput) is enforced by a precise gear pump (the spinning pump) the sharing out into the single hole throughputs is dependent on the pressure and the flow resistances of the single holes. Only for constant pressure and equal resistances the single hole throughputs are equal, too. The present paper deals with the influence of geometrical inaccuracies of the holes in the spinning die on the fineness and structural variations across the spun fiber bundle.
Numerical Calculation of the Velocity and Temperature Field in the Reverse Roll Coating
Authors: Klostermann R. , Mewes D. 
Published: December 2013

Abstract
Rotating rolls are used to distribute liquids onto papers or other materials in order to coat their surfaces with thin films for further technical applications of the composed materials. In this contribution a numerical method is applied which solves the momentum balance in the liquid phase with the support of the Finite Element Method (FEM), taking free surfaces into consideration. The coupled equations of momentum and energy are solved on the basis of the Boundary Element Method (BEM). The process parameters are summarized in the friction number, the capillary number, the Reynolds number, the Stokes number and several ratios of the linear dimensions. Their influence on the fields of pressure, velocity, tension, and temperature is investigated and displayed graphically. A temperature gradient superimposed to the flow through the gap between the roll surfaces results in an additional influence on the velocity field and the coating thickness. The results of the numerical calculations are approximated by rather simple empirical equations.
Structure and Properties of Injection Moldings of β-Crystal Nucleator-added PP
Authors: Fujiyama M. 
Published: December 2013

Abstract
In this paper, we aim at a synergism of improvements of impact strength of polypropylene by the addition of β-crystal nucleator and of its rigidity by the addition of α-crystal nucleator. Co-addition of both the nucleators has been studied. 30 ppm of γ-quinacridone which is a β-crystal nucleator and 0 to 10000 ppm of talc (FC), aluminum salt of benzoic acid (BA), or dibenzylidene sorbitol (GA) which are α-crystal nucleators were added to a homo isotactic polypropylene (PP). Flexural and lzod impact test specimens were injection-molded from the PPs under constant molding conditions and the structure and properties have been investigated. Although the α-crystal nucleators scarcely affect the β-crystal content (K value) at nucleator contents below 100 ppm, the K value decreases with increasing nucleator content at contents above 100 ppm. The decrease is in the order of BA > GA > TC Although the lzod impact strength scarcely changes at α-crystal nucleator contents below 100 ppm, it decreases with increasing nucleator content at contents above 100 ppm. The decrease is the larger as the decrease of K value is the larger. The flexural modulus shows a reverse tendency of the lzod impact strength. From above, it may be said that the properties of injection molding of β- and α-crystal nucleator-added PP are unitarily determined by the β-crystal content and thus the expected synergism could not be obtained.