bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive Extrusion of Styrene Polymers
Authors: Michaeli W. , Frings W. , Höcker H. , Berghaus U. 
Published: December 2013

Abstract
Reactive extrusion is the term used to denote a plastics processing method in which an extruder is used as a reactor for the continuous synthesis and modification of polymers. This paper describes the manufacture of polystyrene and styreneisoprene copolymers by a reactive extrusion process: anionic “living” s-butyl lithium initiated bulk polymerization was performed in a co-rotating closely intermeshing twin screw extruder. The results of the process analysis show that living polymerization of styrene can be performed in a screw-type reactor, despite the high reaction temperatures of over 200 °C. The polystyrene melt can be modified in bulk with comonomers or coupling reagents immediately after polymer synthesis. Depending on the raw material, formulation, and process parameters, the process variants developed and analyzed (homopolymerization of styrene, copolymerization of styrene-isoprene mixtures, sequential polymerization of styrene and isoprene) resulted in styrene polymers with widely differing structural characteristics and properties. For example, the copolymerization or styrene-isoprene monomer mixtures produced poly [(isoprene-co-styrene)-b-styrene]. The sequential polymerization of styrene and isoprene led to poly(styrene-b-isoprene) contaminated with partly crosslinked low molecular weight polyisoprene. The polyisoprene content is presumably formed by side reactions due to the high reaction temperatures.
The Role of Process Parameters in Blow Molding and Correlation of 3-D Finite Element Analysis with Experiment
Authors: deLorenzi H. G. , Taylor C. A. 
Published: December 2013

Abstract
The paper describes a series of blow molding trials on two different polymers under a variety of processing conditions. The tests were performed to investigate factors that affect the variation of wall thickness in a blow molded part. In addition, a numerical analysis was performed to predict the wall thicknesses. A major outcome of the tests was that the relative thickness distributions in the parts were independent of processing conditions and of the material used to form the part. The primary influence of the processing conditions was to put more or less material into the part, but they did not significantly affect the relative distribution of the polymer. The analysis gave a good overall prediction of wall thickness distributions.
Image Simulation and Evaluation of Fiber Orientation Distribution
Authors: Hamada H. , Maekawa Z.-I. , Xia M. , Nakeno I. 
Published: December 2013

Abstract
A new method is presented for analyzing fiber orientation distribution in fiber reinforced composites. A fiber orientation state in fiber reinforced composites is first obtained from soft X-ray image by making contract micro-radiograph (CMR). The distribution of the fiber orientation is measured by a fiber orientation index G(θ) as proposed in this paper. Furthermore, a computer simulation for the fiber orientation distribution is carried out in order to evaluate the fiber orientation index G(θ). It has been found that the value of the fiber orientation G(θ) decreases with an increase in the scatter of the fiber orientation distribution. Not only the direction but also the degree of the fiber orientation can be shown from the curve of the fiber orientation index G(θ). The result shows that this method is easy and useful to evaluate the fiber orientation distribution in fiber reinforced composites.
Flow Visualization and Residence Time Distributions in a Modular Co-rotating Twin Screw Extruder
Authors: Kim P. J. , White J. L. 
Published: December 2013

Abstract
A flow visualization study is reported for the motions of a mineral oil and a thermoplastic polymer individually in a modular co-rotating twin screw extruder. Flow in particular elements and combinations of elements is described. Experiments were also carried out to determine the residence time distribution. The influence of modular screw configuration and screw speed on residence time distribution has been determined. It was found that replacing screw elements with kneading discs or left handed screw elements increases residence time and broadens the residence time distribution. Increasing screw speed at fixed feed rate reduces both the mean residence time and the variance σ2 of the residence time distribution. Increasing feed rate at fixed screw speed has a similar effect. The variation of σ2 with position along the screw axis was measured. The results are interpreted in terms of the fluid mechanics of twin screw extruders including the Akro-Co-Twin Screw program.
Short Glass Fiber Reinforced PA 6 and ABS Blends
Authors: Kannan K. , Misra A. 
Published: December 2013

Abstract
A 70:30 blend of polyamide 6 (PA 6) and acrylonitrile butadiene styrene terpolymer (ABS), with and without a compatibilizer, was used as the matrix for reinforcement with short glass fibers. The compatibilizer used was a copolymer of styrene maleic anhydride (SMA) and its level was kept at 5 wt.-% in the blend. The glass fiber content was varied from 10 to 30 wt.-%. The blends and corresponding composites were compounded using a single screw extruder and test samples were prepared by injection molding. Tensile, flexural and impact properties were determined using the injection molded test samples according to ASTM standards. Morphological studies were carried out on fractured tensile test specimens using scanning electron microscopy (SEM). In general, the mechanical properties improved by the addition of glass fibers to the blend matrices and increased with increasing glass fiber content. The compatibilizer (SMA) has no favorable effect on the mechanical properties of the composites although it has a significant effect on the blends of PA 6 and ABS. SMA increases the melt viscosity of the blend and its addition to the blend results in greater damage to the fibers in the composite during processing. The fiber-matrix adhesion appears to be better in the absence of SMA. The morphological observations have been correlated with mechanical properties.
Morphological Changes of a Polymer Blend into a Twin-Screw Extruder
Authors: De Loor A. , Cassagnau P. , Michel A. , Vergnes B. 
Published: December 2013

Abstract
The dispersion of an elastomeric phase (blend of two miscible copolymers: ethylene-vinyl acetate and ethylene-methyl acrylate) in a polypropylene matrix along a corotating twin-screw extruder was studied experimentally. A sliding barrel allowed a direct access to the screws and thus permitted a rapid cooling and sampling. The dispersion of the elastomeric phase was controlled by scanning electron microscopy and the size distribution was obtained by image analysis. The particle size distribution was measured at different locations along the screws in order to quantify the evolution of the morphology. Complementary studies were carried out on a pre-shearing rheometer (Rheoplast) in order to study the influence of the mechanical treatment upon particle size. The dispersion of the elastomeric phase was observed at the capillary exit by the above mentioned techniques. The results of these different experiments enhance the importance of the melting mechanism and put in evidence that the final morphology of the blend is controlled by the opposite mechanisms of break up and coalescence.
Selecting Continuous Compounding Equipment Based on Process Considerations
Authors: Canedo E. L. , Valsamis L. N. 
Published: December 2013

Abstract
The most widely used pieces of equipment in plastics compounding are continuous mixers and intermeshing corotating twin-screw extruders. Key design aspects and processing characteristics of these two machines are compared and examples of processing typical compounds in both types of equipment are presented and discussed.
Peroxide Induced and Thermal Degradation of Polypropylene
Authors: Ebner K. , White J. L. 
Published: December 2013

Abstract
An experimental study of the peroxide induced degradation of polypropylene is described. Experimental studies in a batch mixer, a single screw extruder and in a Leistritz modular counter-rotating twin screw extruder are presented. Three different screw configurations were used in the latter machine. When comparisons are made at the same temperature, peroxide level and residence time, the greatest extent of degradation is found in the twin screw extruder and the poorest in the single screw extruder. These differences seem associated with the rapid effective melting in the twin screw extruder and the slow melting and poor mixing in the single screw extruder. Of the three modular twin screw configurations, the configuration containing no intense shearing elements is most effective. Experiments based on removing the modular screw and following the reaction as a function of position suggests that Leistritz shearing elements cause rapid heating and reaction of the peroxide before it is mixed into the polypropylene matrix.
Reactive Blending of Polyamide 6 and Polycarbonate
Authors: Valenza A. , La Mantia F. P. , Gattiglia E. , Turturro A. 
Published: December 2013

Abstract
In this work structure and mechanical properties of blends of bisphenol-A polycarbonate with polyamide 6 with different molecular weights and different terminal groups are presented. The results show the important role played in the change of the morphology and in the improvements of the mechanical properties by the increasing content of NH2 terminal groups. These results are attributed to the reactions during melt mixing of such groups with polycarbonate.
The Effects of Recycling and Degradation on Parison Extrusion
Authors: DiRaddo R. W. , Pecora L. , Garcia-Rejon A. 
Published: December 2013

Abstract
Finished goods manufactured by the extrusion blow moulding process are strongly dependent on the parison formation stage, since it is the primary step in the process. The magnitude of the die swell and the degree of sag exhibited by the parison, after being extruded from an annular die, are dependent on the material's molecular structure and strongly affect the performance of the final product. Repassing or recycling of polymeric materials results in degradation reactions that modify the molecular structure, and therefore of parison swell and sag. Polyethylene simultaneously undergoes crosslinking and chain scission. Polypropylene undergoes predominately chain scission. The extent of these degradation reactions can be minimized with the use of appropriate stabilizers. This work involves the study of the effects of repassing on the parison formation stage of extrusion blow moulding. The repassing of the same material gives a representation of what occurs when recycling is undertaken. The effect of stabilizer addition is also studied. Particular emphasis is placed on parison swell and sag.
Stationary and Dynamic Analysis of Film Casting Process
Authors: Barq P. , Haudin J. M. , Agassant J. F. , Bourgin P. 
Published: December 2013

Abstract
A viscoelastic model for PET cast film extrusion is developed on the basis of some important assumptions: constant width, vertical film, isothermal regime, Maxwell's constitutive equation. The general model is non-stationary, but it can be first used to cope with steady-state extrusion, which makes it possible to introduce the concept of “unattainable region”, as in fiber spinning. Then the dynamic responses to random or sinusoidal fluctuations of the chill-roll velocity are analyzed. The predictions of the thickness response are in good agreement with experimental observations.
Bulk Density of Plastic Pellets in a Screw Channel
Authors: Potente H. , Schöppner V. 
Published: December 2013

Abstract
For a correct calculation of the material throughput of single screw extruders in the by solids dominated feed area, the accurate knowledge of the effective bulk density is important. In the screw channel the bulk density measured in a quasi infinite vessel cannot be achieved during processing. The effective density is reduced according to the wall influences. If a two component system exists in the feed area, for example, when processing moulding compounds or regrind, then the bulk density changes likewise. In the following a procedure is described, by which the effect of the screw core measurement and the percentage composition of two material mixtures on the effective bulk density can be calculated.
Blending of SAN and SBS in Corotating Twin-screw Extruders
Authors: Kim Jin Kuk , Lee Si C. , Park Hyun K. 
Published: December 2013

Abstract
Polymer blends have been drawing attention with the development of the polymer industry. The characteristics of toughened SAN/SBS polymer blends are reported in this study. The effect of the screw configuration on the properties of polymer blends has been investigated. This study also deals with the effect of the operating temperature on the properties of the polymer blend. The microphotographs show SBS (Styrene-Butadiene-Styrene) domains in the SAN (Styrene-Acrylonitrile) matrix. This explains that the well dispersed rubber particles do not always contribute to the good mechanical properties such as impact strength. However, this effect contributed to the fluidity of the molten polymer blends.
Compounding and Morphology of Nylon/Ethylene-Propylene Rubber Reactive and Nonreactive Blends
Authors: Scott C. E. , Macosko C. W. 
Published: December 2013

Abstract
The processing behavior and morphology are investigated for nonreactive and reactive nylon/ethylene-propylene rubber blends. The nylon (PA) is a partially aromatic amorphous nylon with amine termination. The rubbery phases are an ethylene-propylene rubber (EP) and a similar ethylene-propylene rubber (EP-MA) with 0.7% grafted maleic anhydride. The nonreactive PA/EP blends show poor interfacial adhesion between the two phases. The reactive PA/EP-MA blends show excellent adhesion and much smaller dispersed phase domain sizes. The interfacial chemical reaction affects several separate parameters which influence the size of the dispersed phase: the formation of a copolymer at the interface which reduces the interfacial tension; different rheological properties of the modified and unmodified rubbers; the effect of the interfacial reaction on the rheology of the blend; changes in process parameters due to the effect of the interfacial reaction; reduction in the rate of particle-particle coalescence due to the presence of the copolymer at the interface; as well as other effects. A semi-empirical relationship is used to separate the effects of phase rheology and applied mixing stress.
Approximate Simulation Method on the Three-dimensional Polymer Melts Flow in a Die
Authors: Matsunaga Keishi , Sakaki Kazutaka , Kajiwara Toshihisa , Funatsu Kazumori 
Published: December 2013

Abstract
Two kinds of practical approximate simulation methods for three-dimensional viscoelastic flow in a die have been developed by which solutions at high shear rate can be obtained with low memory capacity and CPU time. The velocity and stress fields were calculated separately. The velocity field was obtained using the pure-viscous non-Newtonian model and the stress field using the viscoelastic model by substituting this velocity field. In one case the White-Metzner model was applied as a viscoelastic model without a square term in stress. In the second case the stress field was calculated by the streamwise integration which could apply even to the viscoelastic model including the square of stress. In addition a modified pure-viscous non-Newtonian model has been developed respresenting the strain-thickening elongational viscosity in order to extend these approximate methods to similar materials. The velocity field which was calculated using a modified pure-viscous non-Newtonian model was considerably closer to that for the viscoelastic model with the same flow characteristics as shown for the original pure-viscous non-Newtonian model.
On the Simulation of Thermoplastic Injection Moulding Process
Authors: Titomanlio G. , Speranza V. , Brucato V. 
Published: December 2013

Abstract
Numerical simulation of the injection moulding process of thermoplastic polymers has been performed on the basis of the Williams and Lord model and its recent extensions. The aim of the simulation was to identify material properties which play a relevant role to process modelling, including post filling stages. Predictions improve significantly by taking into account the effect of pressure on both viscosity and crystallisation kinetics. Several features, however, are not satisfactorily predicted. Also the relevance of convection during packing has been evidenced especially with reference to gate sealing time. As highly oriented crystalline structures are present in the final moulded object, the enhancement of crystallisation kinetics by the effect of flow is suggested as the phenomenon to be accounted for in order to gain a quantitative description of the whole process.
Control Volume Finite Element Method for Mold Filling Simulation
Authors: Wang T. J. , Lee L. J. , Young W. B. 
Published: December 2013

Abstract
This work presents two methods to improve the spatial accuracy of traditional control volume based finite element method for the mold filling simulation. The first method is based on the flow front mesh refinement which results in a better numerical accuracy near the flow front region without any need of remesh. The second method, flow front tracking, traces the exact location of the flow front. Together with local remesh, the spatial accuracy is improved. Application of both methods to the mold filling process in resin transfer molding (RTM) is presented.
Non-isothermal Dispersive Flow of a Rubber Mixture Inside an Internal Rotor Mixer
Authors: Malkin A. Ya. , Baranov A. V. , Dakhin O. Kh. 
Published: December 2013

Abstract
The paper is devoted to theoretical and experimental investigation of hydrodynamics, heat exchange and kinetics of dispersing of carbon black with a rubber mixture in a chamber of an internal mixer. Modeling of the process is based on use of a rheological equation of a “power” type. A possibility of slipping along a wall is taken into consideration in formulation of boundary conditions. Results of model calculations gave ground for the engineering method of calculations of optimal values of the size of the gap between a wedge of a rotor blade and a wall of a chamber. Comparison of such principal characteristics of a mixing process as average temperature of a stock and the degree of dispersion demonstrated quite good correlation of calculated and experimental data.
Mixing Ring
Authors: Ingen-Housz A. J. , Norden S. A. 
Published: December 2013

Abstract
A new mixing device, to be mounted on the tip of a single screw extruder, is equipped with a freely rotating ring. Its homogenising action is clearly understood and explained. In order to understand its dispersing action experiments have been performed in order to find proof of the presence of elongational flow. They regard visualisation of the flow in a transparent model and blending of PS into PE with various viscosity ratios. Aspects of design and applications are discussed.
Relationship of Stresses in Blown-film Processes
Authors: Kurtz S. J. 
Published: December 2013

Abstract
Fabrication conditions and material rheology control the process of film blowing and limit the possible shapes the bubble may take as well as the ranges and ratios of stresses within the bubble. In order to understand bounds on the stresses during the blowing process, we explore the constraints imposed by force balances, the thin shell approximation, and thermodynamics. We show that the ratio of axial stress to hoop stress is independent of the explicit terms for film thickness, velocity, heat transfer, and the rheology of the material. In addition, we demonstrate that the ratio of the axial stress to the hoop stress can be calculated at any point in the blown-film requiring only values for the pressure drop across the bubble, the shape of the bubble, and the force pulling up the bubble. Experimental results, as well as certain theoretical evidence, strongly indicate that the ratio of axial to hoop stress is everywhere greater than 1 in the standard blown-film process. If this is generally true, then the stress relations we derived can be employed to test the applicability of various theoretical models of the blown-film process.
Numerical Simulation of Polymer Forging
Authors: Haudin J. M. , Monasse B. , Valla T. , Glommeau S. 
Published: December 2013

Abstract
Previous work has shown that numerical simulation does not provide a correct description of compression experiments if the rheology of the polymer in the solid state is deduced from tensile tests. Therefore, a new method is proposed for the determination of the coefficients of G'sell's constitutive equation, in order to simulate the forging process. It also gives access to a parameter characterizing the friction conditions between the polymer and the tool. It is based on isothermal compression of polymer cylinders with an appropriate geometry and on its complete interpretation by means of computer simulation using the finite element code FORGE2. This original procedure is applied to polyoxymethylene.
Thermal/Peroxide Induced Degradation and Maleation of Polypropylene by Reactive Extrusion
Authors: Kim B. J. , White J. L. 
Published: December 2013

Abstract
Experimental studies of three types of reactive extrusion are reported: thermal degradation, peroxide induced degradation and maleation of polypropylene for intermeshing modular co-rotating and counter-rotating twin screw extruder. The studies were carried out in a modular intermeshing twin screw extruder which can be co-rotating or counter-rotating and possesses different screw configurations. Generally thermal degradation was found to be more effective in intermeshing counter-rotating twin screw extruders when similar screw configurations and operating conditions are used. For peroxide induced degradation both counter-rotating and co-rotating machines performed about the same. For the maleation reaction the co-rotating twin screw extruder achieves higher conversions than the counter-rotating machine with all screw configurations and conditions studied. It would appear that the intermeshing counter-rotating twin screw extruder operates at a higher temperature and has poorer mixing characteristics than the co-rotating machine. Differences between the co-rotating and counter-rotating machines decrease with introduction of kneading disc blocks.
Tubular Film Blowing
Authors: Liu C.-C. , Bogue D. C. , Spruiell J. E. 
Published: December 2013

Abstract
The literature on tubular film blowing is contradictory, even on such basic matters as to whether increasing inflation pressure increases or decreases the bubble radius. To provide a solid experimental base for physical understanding and theoretical modelling, detailed on-line measurements were made using three polyethylenes (a low density, a linear low density and a high density material, all of melt index 1.0). The measurements included blow-up ratio as a function of inflation pressure and take-up ratio; the melt temperature and the air flow rate were also varied. On-line radius, velocity and temperature measurements along the film were made in some runs. For the most part the data showed an “intuitive” effect of inflation pressure on blow-up ratio; that is, increasing the pressure caused the final radius (the blow-up ratio) to increase. However, at high blow-up ratios (typically values of 2 to 3, depending on the material and processing conditions), regimes having a “counterintuitive” relationship were observed in some cases. There were not substantial differences among the three materials except that the low density material was less prone to instabilities at high blow-up ratios.