bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscibility and Mechanical Properties of Poly(ether imide)/Liquid Crystalline Poly(ester imide) Blends
Authors: Ryu Changyeol , Seo Yongsok , Hwang Seung Sang , Hong Soon Man , Park Tae Suk , Kim Kwang Ung 
Published: December 2013

Abstract
As a part of continuous study to search for the high performance in situ composite, this study examines the miscibility of liquid crystalline poly(ester imide) (PEsI) with poly(ether imide) (PEI) and its effect on the mechanical properties and the morphology of the blends of these polymers. Liquid crystalline polymers (LCPs) were synthesized from trimellitic anhydride and α,ω-diaminoalkane with 8, 10, 12 methylene groups. Thermal condensation of these diacids with 4,4′-diacetoxybiphenyl yielded the corresponding imides of thermotropic homopolyesters. Optical polarized micrographs show that the synthesized poly(ester imides) have the smectic structure. Partial miscibility was observed from the shift of the glass transition temperature determined by differential scanning calorimetry. Increasing concentration of the liquid crystalline PEsI in the PEI/PEsI blends shifted the glass transition temperature of the PEI phase to a lower temperature. Mechanical properties of the PEI/PEsI blends were changed with the number of methylene units in PEsI. Morphologies of the partially miscible system were found to be quite different from those of an immiscible system. Strong adhesion between the matrix (PEI) and dispersed phase (LCP) was observed, but fine fibril formation was not possible due to the absence of smectic-nematic transition.
Simulation of Non-isothermal Flow in Twin Screw Extrusion
Authors: Chen Z. , White J. L. 
Published: December 2013

Abstract
Procedures are described for computation of pressure, fill factor and temperature profiles in a molular co-rotating twin screw extruder with multiple feed ports and vents. This is a modification of our earlier Akro Co-Twin Screw software. Sample calculations are given for non-isothermal flow simulation of compounding of thermoplastics with talc. It is shown that the effect of temperature on viscosity plays a significant role in pressure fill factor, and temperature profiles and in overall temperature rise.
On-line Measurement of Residence Time Distribution in a Twin-screw Extruder
Authors: Chen Tong , Patterson W. I. , Dealy J. M. 
Published: December 2013

Abstract
A simple optical on-line residence time distribution (RTD) measurement technique has been developed. Changes in extrudate light transmittance are monitored by a photomultiplier. A He-Ne laser is the light source with carbon black as the tracer. The RTD of a ZSK-30 twin-screw extruder was measured using this technique. The effects of feed rate, screw speed, and melt viscosity on the RTD were studied. Also, the effect of the presence of an in-line rheometer on RTD was examined. The advantages and disadvantages of the technique are discussed.
Simulation of the Screw Bowing Effect in an Intermeshing Counter-Rotating Twin-screw Extruder
Authors: White J. L. , Adewale A. O. 
Published: December 2013

Abstract
The bowing of screws in an intermeshing counter-rotating twin screw extruder due to polymer melt flow induced lubrication pressures between screws is modeled. It is shown that the extent of screw bowing depends upon screw aspect ratio, the modulus of elasticity of the screw, screw design, extent of intermesh, level of shear viscosity and melt throughput.
Solids Conveying and Melting in a Starve Fed Self-wiping Co-rotating Twin Screw Extruder
Authors: Bawiskar S. , White J. L. 
Published: December 2013

Abstract
A flow visualization study of starve fed solids conveying in single screw and a modular self-wiping co-rotating twin screw extruder is observed inflow visualization experiments. Single screw extruders exhibit forward Archimedean transport of material on the undersides of the screw. Self-wiping co-rotating twin screw extruders conveying forward in the intermeshing region and in the region near the apex between the screws. Observations are reported of the melting of solid pellets and possible melting mechanisms are discussed.
Modeling the Residence Time Distribution of a Non-Intermeshing Twin Screw Extruder
Authors: Thompson M. , Puaux J. P. , Hrymak A. N. , Hamielec A. E. 
Published: December 2013

Abstract
The residence time distribution (RTD) of a counter-rotating non-intermeshing twin screw extruder has been studied by a radioactive tracer technique. RTDs were measured at both the die exit and at the first compounding zone of the extruder. The operating parameters investigated were: screw speed, screw flight stagger, and barrel temperature. These parameters have an effect on the mixing efficiency. The mixing efficiency was characterized by fitting measured response data with models comprised of different combinations of ideal reactor elements. The empirical flow models tested were: plug flow and tanks-in-series (with and without recirculation), plug flow and axial dispersion, and the Wolf-Resnick model. The fitted model parameters characterized the observed changes in the RTD due to the variation of the operating parameters.
Modelling and Experiments of Squeezing Flow of Polymer Melts
Authors: Zhang W. , Silvi N. , Vlachopoulos J. 
Published: December 2013

Abstract
A one-dimensional purely-viscous model that includes slip at solid boundaries is proposed to study the flow of polymeric materials when compressed between two approaching parallel surfaces. A squeeze-flow rheometer was designed and built to compress polymer melts under controlled conditions of constant closing speed and constant applied force for different conditions at the polymer-solid interface. One of the purposes of this study was to investigate how the interface conditions influence the flow field during squeezing. The experimental findings revealed that the model can adequately predict the squeezing force for slow squeezing of relatively thin samples. For fast squeezing, however, the experiments appear to suggest the need of including elongational effects in the modelling of the material behavior.
Crystallization Behavior of Carbon Fiber Reinforced Polyamides (I) Dynamic and Isothermal Crystallization
Authors: Zhang Z. , Kitano T. , Hatakeyama T. 
Published: December 2013

Abstract
Polyamide (PA) was compounded with carbon fiber (CF) with various contents (0, 5, 15, 20 vol.-%) using an elastic extruder. The effect of both the carbon fiber contents and the compounding method on thermal behavior and characteristics of crystallization are studied using differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and polarizing optical light microscopy (POL). Thermal investigation was carried out under programmed cooling and isothermal conditions. The following results were obtained: (1) The crystallization temperature became higher with the increase of carbon fiber content, while the melting temperature and enthalpy were scarcely affected by the carbon fiber content. (2) The compounding methods affected the thermal behavior of composite systems. The samples that have been extruded twice have higher crystallization and melting temperatures as well as higher melting enthalpy. (3) Isothermal crystallization was observed using DSC. From the rate constant k and Avrami's index n, it was found that crystallization was accelerated by the presence of carbon fiber without changing the type of nucleation. (4) The polarizing micrographs showed that the nucleation of PA occurred on the surface or close to the CF.
Unstable Gas Penetrations in Symmetrical Rib Channels During Gas-assisted Injection Molding
Authors: Yang S. Y. , Huang F. Z. 
Published: December 2013

Abstract
During gas-assisted filling, gas penetrations in symmetrical rib channels are found never symmetrical. The development of this unsymmetry is observed and its cause is analyzed. The system of gas penetrations in melt in symmetrical rib channels is found unstable. Symmetry is upset upon perturbation. Symmetrical gas-channel ribs in gas-assisted injection molded parts should be avoided.
Stress Controlled Simultaneous On-line Measurements of Viscosity, Flow Exponent, and Melt Index
Authors: Gleißle W. , Schulze V. 
Published: December 2013

Abstract
Capillary rheometers have been installed on-line very successfully for real time control of the quality of polymers in production and processing. A substantial extent of the real time information about the state of material and process is reached using an on-line rheometer with a wedge-shaped slit working under pressure controlled conditions. True viscosity, flow exponent and melt flow index can be measured simultaneously and changes in average molecular weight and molecular weight distributions are indicated immediately.
Modeling and Finite Element Analysis of Flow in SMC Compression Molding
Authors: Youn S.-K. , Lee E.-S. 
Published: December 2013

Abstract
A new flow model is developed for the analysis of compression molding of sheet molding compounds (SMC) and a penalty finite element formulation is presented to predict flow front progressions more accurately. In this model SMC is assumed nonisothermal fluid, which has different viscosities in extension and in shear. The flow is allowed to slip at the mold and is resisted by friction force which is proportional to the relative velocity at the mold surface. For the verification of the model, the press force and flow patterns are compared with those of experiments and available results by other works in this field. It is also demonstrated, using the computational procedure described and the proposed model, that optimal initial charge shapes for the filling can be effectively computed.
Melt Strength and Elastic Behaviour of LLDPE/LDPE Blends
Authors: Micic P. , Bhattacharya S. N. , Field G. 
Published: December 2013

Abstract
Differences in processability between linear low denisty polyethylene (LLDPE) and low density polyethylene (LDPE) as well as for their blends subjected to extensional flow were assessed in terms of melt strength and elastic parameters from shear flow such as storage modulus (G′), and first normal stress difference (N11 – N22). The results revealed similar synergistic effects for these parameters in the LDPE rich blends. A DSC test carried out on these LLDPE/LDPE blends when fast cooled disclosed the existence of two phases in the molten blends for the same composition range where the melt strength synergism was observed. The results are discussed in terms of the influence of the different molecular structures of the blend polymers and their miscibility on the measured melt strength. A mechanism is suggested to explain the observed synergistic phenomenon.
Analysis of the Mold Filling Process with Phase Change Considering the Non-steady Effect
Authors: Kim M. S. , Lee W. I. , Lee J. S. 
Published: December 2013

Abstract
Polymer mold filling is a non-Newtonian, non-isothermal, non-steady process with free surface. It is well known that the fountain flow effect in the flow front region and the solidified layer near the cold mold wall have significant effect on the mold filling process and thus the mechanical properties of the molded parts. In this study, a non-isothermal, non-steady mold filling process including the solidified layer as well as the fountain flow effect was analyzed numerically using the finite element method. Shear rate dependency in the viscosity was taken into account by employing the Cross model. Single-step algorithm was used for the numerical integration in time and the flow front was advanced by the explicit scheme. The resulting system of algebraic equations was solved using the Picard iteration technique. In order to verify the validity of the numerical scheme, energy balance and mass conservation were checked. It was found that the energy and mass balances were satisfied within reasonable accuracies. The importance of the non-steady term was assessed by analyses done in a similar manner by assuming that the process is quasi-steady. Two results thus obtained were compared. The quasi-steady assumption was found to be insufficient in describing the inherent non-steady effect during mold filling.
Surface Defect Formation in the Injection Molding of Acrylonitrile-Styrene-Acrylate Polymers
Authors: Chang M. C. O. 
Published: December 2013

Abstract
Surface defects in the injection molding of acrylonitrile-styrene-acrylate (ASA) weatherable polymers, such as “chevrons”, “non-uniform haze” and “step defect “, are examined. A criterion is proposed based on a flow instability mechanism which suggests that recoverable shear strain, shear stress, and coefficient of friction are the key factors controlling the formation of surface defects. The criterion is supported by various experiments.
Theoretical and Experimental Investigations of the Melting of Pellets in Co-Rotating Twin-Screw Extruders
Authors: Potente H. , Melisch U. 
Published: December 2013

Abstract
Knowledge of the plasticizing behavior in tightly intermeshing, co-rotating twin-screw extruders is of crucial importance for assessing the compounding process. Experiments were conducted on a laboratory extruder in order to establish the parameters that influence the melting process. Solidified samples of material were taken from the screw and microtome cuts produced from the plasticizing section. These were then assessed on the basis of image analysis. This visualization of the solid and molten phases which are present simultaneously together with the distribution of the two phases made it possible to quantify the reduction that occurs in the amount of solid material over the length of the screw configuration employed.
A model is additionally presented for the calculation of the melting lengths and the melting profiles. This works on the basis of individual particles which are uniformly dispersed in the polymer melt. Allowance is made for the temperature increase in the solid material conveying section. A comparison of calculated and experimentally determined melting lengths revealed a satisfactory level of agreement.
An Improved Flow Simulation Model for a Tangential Counter-Rotating Twin Screw Extruder
Authors: Bang D.-S. , White J. L. 
Published: December 2013

Abstract
In this paper we simulate the flow of a Newtonian fluid in a tangential counter-rotating twin screw extruder using a cylindrical coordinate lubrication theory model. Special attention is given to the material flows leading to mixing specially to inter-screw and backward leakage between the screws, and how they vary with process conditions.
Modeling and Experimental Study of the Flow in a Simplified Cavity Transfer Mixer
Authors: Wang C. , Manas-Zloczower I. 
Published: December 2013

Abstract
The Cavity Transfer Mixer (CTM) was primarily designed as a distributive mixing device to be used as an add-on unit to existing extruders. Understanding the flow patterns and characteristics within the CTM is of fundamental importance for a proper design and optimum processing. Due to the complex geometry and the transient characteristics of the flow, solving for the flow patterns in the CTM is not an easy task. However, some of the design features of the CTM can be reproduced in a simplified device which will allow more detailed experimental and numerical investigation. In this work such a simplified device was built and used to reveal some of the features of the flow patterns and the influence of one design parameter (cavity shallowness) on the dispersive mixing efficiency.
Simulation of Continuous Polymerization in a Modular Intermeshing Co-rotating Twin Screw Extruder
Authors: Kye H. , White J. L. 
Published: December 2013

Abstract
A method of modeling chemical reactions in a modular inter-meshing co-rotating twin screw extruder is described. This is applied to simulate the anionic polymerization of caprolactam. Calculations are made for specific modular screw configurations. The screw configurations included both screw elements and kneading disc blocks. Reaction conversion and temperature rise were calculated along the screw axis. The results are compared to experiment.
Reactive Blending in a Twin Screw Extruder
Authors: De Loor A. , Cassagnau P. , Michel A. , Delamare L. , Vergnes B. 
Published: December 2013

Abstract
We studied the morphology of a reactive blend, constituted by an EVA/EMA phase dispersed in a polypropylene matrix. The dispersed phase was crosslinked in-situ during the extrusion through a transesterification reaction, catalysed by dibutyltin oxide. Rheological studies allowed to define the changes in rheological behaviour during the crosslinking reaction. Using a flow model developed for twin screw extruders, we computed the reaction extent along the screws and the corresponding blend morphology using a very simple approach. Theoretical results underestimate the extent of the reaction, but explain qualitatively the general tendencies when varying operating parameters.
Structure and Properties of Inflation Films of β-Phase Nucleating Agent-Added Polypropylene
Authors: Fujiyama M. 
Published: December 2013

Abstract
To a homo-isotactic polypropylene (PP) was added 0 to 10 ppm of quinacridonequinone which was a β-phase nucleating agent for PP. The structure and properties have been studied on the inflation films processed from the PPs by the water-cooling or air-cooling methods. The effect of cooling conditions on crystallization has been also studied for reference. Even PPs containing β-phase nucleating agent do not form the β-phase but the smectic or α-phase at low cooling temperature. However, compared with PP without β-phase nucleating agent, they form the α-phase at lower cooling temperature and form the β-phase at high cooling temperature. Even PPs containing β-phase nucleating agent form only the smectic phase in the water-cooled inflation films but form the β-phase in the air-cooled inflation films if β-phase nucleating agent contents are high. Although the film properties are generally not so much affected by the addition of the β-phase nucleating agent, the dart impact strength increases for the air-cooled films which contain the β-phase.
Analytical Study on Flow and Distributive Mixing of a New Type Pin Mixing Section for Screw Extruder
Authors: Yao W. G. , Takahashi K. , Abe Y. 
Published: December 2013

Abstract
A new type of pin to be installed in mixing section of screw extruder is proposed based on the results of numerical calculation of flow field and local mixing efficiency. Two problems presented in general pin mixing section, i.e., the lack of randomization in mixing mechanism and the formation of dead spots, can be solved through diagonally-channeling pins from top to bottom. From the results of numerical analysis of local mixing efficiency it is known that in the cross-section of standard screw (in this study called “cavity”) there are only small regions with high mixing efficiency which is mainly near the two upper corners of the cavity. If two pins are put into the cavity, large high mixing efficiency regions occur in the scope from cavity top to about 1/3 flight height. But, in the case of inserting two holed pins into the cavity, high mixing efficiency regions are distributed in nearly all over the cavity. It is impossible to get such useful information by experiments. Even though the calculation was confined in cross-section of pin mixing section, it has directive significance in designing the practical pin mixing section in the light of theory of distributive mixing.
Development of a Computer Simulation of SCORIM
Authors: Pittman J. F. T. , Aguirre P. , Ding D. 
Published: December 2013

Abstract
SCORIM (shear controlled orientation in injection moulding) is a new technology using pairs of reciprocating pistons connected to the runner system to impose shear in the mould during the holding and packing stages; this provides important control over part properties. A computer simulation is set up, and solved numerically to assist with development and exploitation of this novel process. The one-dimensional transient model considers the cooling and solidification of polymer melt, contained between infinite plane parallel plates, whilst subjected to reciprocating shear flow. A non-Newtonian, temperature-dependent viscosity is used, together with temperature-dependent thermal properties and latent heat of solidification. Two operating modes are considered: (1) flow driven by a fixed pressure gradient; (2) an initially fixed flowrate, which falls after a limiting pressure gradient is reached. Results are shown, based on data for a moulding grade polypropylene; these include details of temperature and velocity fields, pressure and flowrate profiles, and frozen-in material strains, which are related to material alignment. In mode (1) operation, flowrate falls rapidly as solidification proceeds. This is not hindered significantly by viscous heating. Frozen-in strain has its maximum value close to the wall, and falls in a series of oscillations to zero on the central plane. In mode (2), if the limiting pressure gradient is too high, viscous heating can prevent cooling, leading to a dynamic thermal equilibrium. In other cases, where cooling is completed, frozen-in strain can show a complex, oscillatory profile, corresponding to a layered structure in the moulding with alternating regions of higher and lower alignment.
Microstructure Evolution During Moulding of Particulate-Reinforced Thermoplastic Composites
Authors: Papathanasiou T. D. 
Published: December 2013

Abstract
Analysis of injection moulded parts made of polystyrene reinforced with spherical glass particles of various sizes reveals the existence of a number of interesting microstructural features. These include the segregation of particles towards the centre-plane of the cavity, their accumulation close to the free surface and the subsequent occurrence of short-shots, the formation of particle-rich layers adjacent to the perimeter of the moulding and the formation of monolayers of particles attached to the cavity surfaces. Some of these features are consistent with and can he explained by the flow patterns associated with the mould-filling process, namely a Hele-Shaw flow on the plane of the cavity and a fountain flow near the advancing free surface. A mechanism is proposed, according to which the segregation of particles at the cavity mid-plane and their accumulation towards the free surface is the result of the combined action of convection, fountain flow and lateral particle migration. The configuration of the gate is shown to have a marked effect on the observed microstructures in edge-gated mouldings, depending on the ratio of the gate size over the particle size, as is clearly illustrated through X-ray radiography in polydisperse systems. As a result of particle accumulation at the free surface, the formation of particle-rich weld lines in mouldings with inserts is also observed through X-ray radiography. The observed microstructures are shown to be strongly influenced by the size of the particles.
Continuous Polymerization of Caprolactam-Polyether Sulfone Solutions in a Twin Screw Extruder to Form Reactive Polyamide–6/Polyether Sulfone Blends and Their Melt Spun Fibers
Authors: Kye H. , White J. L. 
Published: December 2013

Abstract
The continuous anionic polymerization of caprolactam solutions of polyether sulfone in a modular intermeshing co-rotating twin screw extruder has been investigated. The polyether sulfone appears to react with the polymerizing monomer. The polyamide-6/polyether sulfone reactive blends formed have been characterized. Studies were also made of melt spinning reactive blends into oriented filaments. The structure and mechanical properties of the blend melt spun filaments were characterized.