bluuebunny/crossref_metadata_2025_split huggingface dataset:
PP-based Model Compounds as Tools for the Development of High-impact-ethylene-propylene Copolymers
Authors: Gahleitner M. , Hauer A. , Bernreitner K. , Ingolic E. 
Published: December 2013

Abstract
The development of heterophasic PP-copolymers, which are necessary in many applications because of their specific property profile, requires large capacities in pilot plants (or at least in bench-scale reactors) for a systematic variation of the matrix and elastomer properties. A possible alternative are model compounds, where the different components are blended in an extruder. The possibility to evaluate three main influence factors on mechanics of such systems, namely the viscosity ratio between matrix and elastomer phase, the phase compatibility and the composition of the elastomer phase, is demonstrated in a series of investigations. Morphology investigations based on transmission electron micrographs have proven to be an indispensable tool for obtaining systematic information about such blend systems, which can be further used for the development of reactor-based systems.
Free-radical Reactions and Thermal Effects in PE during Pipe Extrusion
Authors: Özcanli Y. Lenger , Mamedov Sh. V. , Aktaş B. , Yalçinyuva T. , Alekperov V. A. , Yilgin R. , Durmus A. , Öksüz S. 
Published: December 2013

Abstract
In this study, various effects on the properties of the material, such as free-radical (FR) processes, oxygen induction time (OIT), melting temperature and melting heat are examined during several stages of the polyethylene (PE) pipe extrusion process. The spectra in the Electron Spin Resonance (ESR) are researched between 77–293 K and in a wide range of magnetic fields. At 77 K a triplet signal in ESR is observed. The parameters of the signal are ΔHm1 ≅ 1:4 – 1:6 mT; ΔHm2 ≅ 1 – 1:2 mT; ΔHm3 ≅ 0:6 – 0:8 mT and g1 ≅ 2:020; g2 ≅ 2:011; g3 ≅ 1:99 and Hyper Fine Structure constant ΔH12 ≅ 2:1 mT; ΔH23 ≅ 5:3 mT. As the temperature increase from 77 K up to 293 K, the signal for g4 ≅ 2:02 (ΔHm4 ≅ 0:7 – 0:8 mT) appears and intensity of signals increase. It is also thought that the triplet observed at 77 K belongs to macroradicals of alkyl (–CH2–CH–CH2), alyl(~CH2 C HCH = CHCH2~), carboanions and the acyl (H C O) radicals of the fourth signal. At room temperature, all the FR's transform into peroxide radicals. The total concentration of the FR's is minimum at 463 K and increases at the outlet of the extruder and the pipe sample.
It is observed that the OIT (Oxygen Induction Time) values decrease as one approaches the outlet of the extruder (from 20–30 to 10–15 minutes), while they increase for the processes of 433 K to 463 K. This event proves that the peroxide radicals form as one passes to room temperature. These results support those of the effects of the extrusion stage on the dynamic-mechanical characteristics [2].
Finally, FR's appear as a result of the breaking of the C-C bonds in the main polymer chains starting from the first step in the extrusion process (433 K) and in the later stages, due to the oxygen in the polymer structure, oxidation processes take place.
Modeling Filler Dispersion along a Twin-Screw Extruder
Authors: Lozano T. , Lafleur P. G. , Grmela M. , Vergnes B. 
Published: December 2013

Abstract
Particle size distribution strongly affects physical and mechanical properties of filled polymers. A new model has been developed to predict agglomerate size distribution in a twin-screw extruder (TSE). The model considers the break-up and erosion processes and it uses agglomerate size population balance in its mathematical formulation. The model parameters were evaluated in simple field flow. This paper shows the validation of the model along the extruder using different screw configurations of a short twin screw extruder. Flow parameters along of the TSE necessaries to apply the new dispersion model have been calculated with ©Ludovic software. Calcium carbonate filled polypropylene system was used as model compound. The agglomerate size distribution was evaluated from micrographs of polished samples at different locations along the extruder obtained by reflected light microscopy in conjunction with-semiautomatic image analysis.
Characterisation of Finite Length Composites
Authors: Gleissle W. , Curry J. 
Published: December 2013

Abstract
This paper is a technical report about the structure and the rheological behaviour of processed polypropylene-glass fibre composites. The present studies has been carried out as a part of the international project on the Characterization of Finite Length Composites initiated and organized by the IUPAC Working Party: Structure and Properties of Commercial Polymers. Seven industrial and university laboratories in Europe and in USA worked together in a common project to investigate the influence of the processing conditions on the rheology and manufacturing behaviour of polymer-glass composites preprocessed in a twin screw extruder. All investigations presented concern the influence of the processing procedure on the structure of the composites such as fiber length destribution, fiber orientation, destribution of the fibre concentration in the sample and the rheology of the composites. The flow behaviour dependent on the processing conditions has been measured using capillary rheometers to investigate the viscosity functions, the entrance and outlet pressures losses as well as for observations of the shape and internal structure of extruded composites. Torsional rheometers for low shear rate, oscillatory and transient viscosity behaviour and for the quantification of fibre orientation with ongoing shear process. Additionaly queeze flow experiments are made.
Most laboratories used analogous recording sytems to documente the primary experimental results. So results are partially given here as direct copies from the original data readings. The different data handling and the transfer of data from laboratory to laboratory for comparison of results leads sometimes to unavoidable inhomogeneous (due to the style and possibilities of the different laboratories) presentation of the results. The present report is a result of data collecting, data comparison and documentation of results over a period of nearly ten years.
Measurement and Prediction of Temperature Distribution in an Injection Molding Cavity
Authors: Manero F. , Kamal M. R. , Lai-Fook R. A. , Varela A. E. , Patterson W. I. 
Published: December 2013

Abstract
A method to measure the melt temperature distribution in an injection mold cavity is developed. A thermocouple is used in the construction of a sensor with a tip that can be adjusted at different depths of a mold cavity, to measure temperature profiles at different positions in the mold. Polymer temperature distributions are measured and factors affecting temperatures and the key variables that influence distributions are determined. Measurements are compared with temperatures obtained from numerical simulation of the injection molding process using a three-dimensional heat transfer analysis. Although showing lower values and generally higher cooling rates, temperature data measured from the mold cavity indicate similar behavior to predicted transient temperature distributions.
Montmorillonite Co-intercalated with Octadecylamine and Stearic Acid by Low Temperature Melting and its Influence on PP Nanocomposites
Authors: Merinska D. , Chmielová M. , Kalendova A. , Weiss Z. , Capkova P. , Šimoník J. 
Published: December 2013

Abstract
Organically modified Na-montmorillonite (MMT) samples were prepared by co-intercalation of octadecylamine (ODA) and stearic acid (STA) using a low-temperature melting procedure A blend of MMT and ODA (with the ratio 1: 0.5) was stirred for one minute at 80°C in a laboratory mixer and then different amount of STA (weight ratios of MMT + ODA: STA = 1 : 0.3 and 1 : 1) were added and stirred for another five minutes. The resulting mixture was annealed at the same temperature for one hour. X-ray diffraction (XRD) powder patterns of two co-intercalated samples contain a non-regular set of d spacings of basal diffractions. The first basal diffraction with d = 4.8 nm probably gives evidence for prevalent bilayer molecular arrangement in the interlayer and the non-regular set of d spacings of basal diffractions indicates possible mixed-layer interstratification and/or disorder in the bilayer arrangement of the interlayer space. The set of basal diffractions in the XRD patterns of co-intercalated samples significantly differs from the set of basal diffractions in the patterns of the samples intercalated by only ODA or STA. XRD patterns of Na-montmorillonite sample intercalated with ODA (in the ratio of MMT: ODA = 1:0.5) and with STA (in the ratio of MMT: STA = 1: 1) contain broadening peaks. Polypropylene (PP) nanocomposite samples were prepared by mixing MMT modified in the described mode into the PP matrix. To improve the PP affinity to intercalated MMT, maleic anhydride modified PP as a compatibilizer was used. The level of PP nanocomposites exfoliation was evaluated by XRD technique. The influence of the nanofiller on mechanical properties was measured by tensile tests, and an improvement of mechanical properties was noticed.
A Study of Processing Conditions on the Properties of Diffraction Optical Elements by Injection/Compression Molding Process
Authors: Tseng S. C. , Liao C. L. 
Published: December 2013

Abstract
The purpose of this work is to develop manufacturing techniques of diffraction optical elements (DOE) and compare the performance of micro injection (/compression) molded products. The DOE mold was fabricated by LIGA-like lithography technique. The optical performance of molded products strongly depends on the replication degree of micro patterns on the surface of DOE. Because of the complex micro patterns on the surface of the DOE, it is very difficult to measure the degree of duplication by traditional microscope measurement like SEM or AFM etc. In this work, a laser computer imaging system was developed to evaluate optical performance of molded parts directly. To achieve better duplication degree and properties of molded DOE, Taguchi's method was employed in the experiments to examine the effects of processing conditions on the performance of molded DOE. Residual stresses of different molded products were measured by a photo-elasticity system. Experimental results reveals that residual stresses of micro injection compression molded elements are much less than those of the micro injection molded ones. This is because compression process provides a higher and more uniform pressure distribution inside the cavity and it can help reduce the unbalanced shrinkage and residual stresses. Compression speed dominates the cavity pressure distribution and becomes the most important factor of final DOE's optical properties.
Radiant Heating of Plastics: Application to Film Blowing Processes
Authors: Benkreira H. , Talford M. C. 
Published: December 2013

Abstract
This paper presents experimental data and a mathematical model for the radiant heat transfer operation used in the production of biaxially oriented polypropylene (BOPP) films by the Double Bubble process. The data was obtained from an industrial pilot plant fully instrumented for the purpose of the study. In the mathematical model the effect of the view factor is considered, along with the effects of natural and forced convection on the heat transfer coefficients. Experiments were also conducted in a laboratory radiant heater to determine the range of heat transfer coefficients experienced under different heating conditions, and analytical methods to determine these are discussed.
Modeling and Analysis of Helicoidal Flow in a Conical Extruder
Authors: Sarioglu A. , Månson J.-A. E. 
Published: December 2013

Abstract
The present paper discusses the unique flow behavior in a new type of extruder. The extruder design is based on a hollow conical assembly of static (stators) and rotating (rotor) parts. Extrusion is achieved from each side of the rotor to provide a two-layer annular product. Flow is helicoidal in the vicinity of the rotor tip and die entry where the polymer layers merge. However, it becomes fully parallel to the main extrusion direction after a certain distance downstream from the rotor tip. Numerical simulations based on the resolution of Navier-Stokes equations using a Generalized-Newtonian viscosity showed that the length of the helicoidal flow depends on die design, viscosity and flow rate ratios between adjacent polymer layers. Analysis of flow variables along the interface showed that the helicoidal flow distance can be increased using a die design inducing lower interfacial shear rate and velocity. When the viscosity ratio and the flow rate of the most viscous polymer are increased, the helicoidal flow can be maintained over a longer distance in the die. Finally, experiments have shown that the advantage of the helicoidal flow is for short fiber orientation in pipes. The fibers are oriented along the streamlines in the hoop direction in the mid-gap of the die; however, they are parallel to extrusion direction in the vicinity of the stators.
Computational Study of Velocity Field in the KE Element of a Modular Ko-Kneader with CFD Method
Authors: Mehranpour M. , Nazokdast H. , Dabir B. 
Published: December 2013

Abstract
Attempts were made to predict the velocity field and shear rate distribution of a Newtonian type fluid in the KE element of the Buss Ko-Kneader by means of CFD method. The role of both rotating and reciprocating motion have been considered in three dimensional flow field. The computed results showed appreciable changes in the velocity counters during a period of reciprocating motion, and these changes were greater for the transverse flow compared to the down channel flow.
The predicted results also showed pronounced variations in the velocity profile of the transverse flow regarding both with direction and extent of drag and pressure flow as a result of reciprocating action, while the down channel velocity profile was found to be almost unaffected.
The extent of shear rate and hence shear rate distribution were found to be dominantly control by the down channel flow while transverse flow has a greater influence in determining the residence time distribution.
Quality Aspects on the Power Cable Core Insulation Extrusion and Thermal Curing Process
Authors: Harlin A. , Huotari P. 
Published: December 2013

Abstract
The insulated core quality of power cables is directly linked to the performance of the cable in its end-use. The high voltage distribution installations at 10 to 500 kV range are large, expensive, and essential for community. Consequently, the most important quality properties are therefore the expected service life of the cable and its manufacturing costs. Standard cable constructions, with the exception of the extra high voltage (EHV) construction for over 385 kV, have substantial overdimensioning in the insulation layer thickness. Medium voltage cables in the range 10 to 35 kV (MV) are increasingly becoming commodity items and the cost function has become critical to the economic viability of cable production. Insulated core quality depends on the raw materials quality, e. g. the purity of the peroxide cross-linkable PE-LD. The extrusion process and insulation curing process should be considered as the major quality aspects. The total quality of the cable can be assured only if manufacturing is made correct at once. In the following is reviewed the good practice and related aspects based on marked field experience.
Investigation of the Mechanical Properties and Chemical Resistance of PC/PBT/Impact Modifier Blends
Authors: Lyu M.-Y. , Pae Y. , Nah C. 
Published: December 2013

Abstract
Mechanical properties, flow characteristics and chemical resistance of polycarbonate (PC)/poly(butylene terephthalate) (PBT)/impact modifier (IM) blends were investigated over the wide composition range of PC and PBT. Mechanical properties of the PC/PBT/IM blends for two different IMs, butadiene based IM and butyl acrylate based IM, were studied. For the study of chemical resistance of the PC/PBT/IM blends, test specimens were dipped in solvent, thinner, and then variations of mechanical properties were analyzed. Tensile and flexural strengths were increased linearly and heat distortion temperature (HDT) also increased as PC content in the blends increased. Impact strength increased drastically as PC content in the blends increased up to 50 wt.-%, and then it leveled out for over 50 wt.-% of PC. Flowability of the blends decreased as PC content increased. Impact strengths of the blends were different from IMs specially at low temperatures. The blends with butyl acrylate based IM showed slightly higher impact strength than the blends with butadiene based IM at 0°C and room temperature. However, the blends with butadiene based IM showed remarkably higher impact strength than the blends with butyl acrylate based IM at the temperatures below 0°C. After the chemical treatment of test specimens, tensile and flexural strengths decreased, and impact strength increased as PC content in the blends increased. PC in the blends would become mild and ductile when it contacted with solvent, thus the impact strength increased while tensile and flexural strengths decreased.
Effect of Elongational Viscosity on the Flow in a Flat Die
Authors: Sun Y. , Gupta M. 
Published: December 2013

Abstract
The flow of a low-density polyethylene in a flat die is simulated using the axisymmetric and planar elongational viscosities estimated in an earlier publication by Beaupre and Gupta. Elongational viscosity is found to have only a limited effect on the velocity distribution at the die exit. However, the predicted pressure drop in the die and the temperature distribution at the die exit changed significantly when the effect of elongational viscosity was included in the simulation.
Fractionated Crystallization and Morphology in Binary Blends of Isotactic PP and HDPE with Cycloolefin Copolymers
Authors: Pimbert S. 
Published: December 2013

Abstract
Crystallization of binary blends of semi-crystalline polyolefins (i-polypropylene and HD-polyethylenes) and amorphous cycloolefin copolymers (COC) was followed by Differential Scanning Calorimetry (DSC). Blend morphologies were investigated by Scanning Electronic Microscopy (SEM). The thermal behavior and morphology of iPP–COC blends are characteristic of immiscible blends. The two crystallization exotherms observed on cooling from the melt were explained in terms of fractionated crystallization. This phenomenon occurs when iPP inclusions are finely dispersed in the COC matrix so that their number is much greater than the number of heterogeneities originally present in the bulk polymer, resulting in the suppression of the heterogeneous nucleation.
A quite different behavior is observed in PE–COC blends. DSC and DMTA results show a significant decrease of both PE Tm and COC Tg, observations usually associated to some polymer miscibility in the amorphous phase. The crystallization mode and the resulting morphologies also appear to be largely dependent on the molecular weights and polydispersity indices of the dispersed phase.
Die Wall Effects, Contact Angles and Slippage in the Flow of Polymer Melts and Polymer-Particulate Compounds with Carboxylic Acids in a Slit Die
Authors: Ahn S. , White J. L. 
Published: December 2013

Abstract
An experimental study of the influence of carboxylic acid additive in polyethylene/filler and polystyrene/filler compounds in slit die is described. Slit die extrusion experiments and contact angle measurements are reported. A series of fillers of varying particle size including carbon black, calcium carbonate, zinc oxide, and talc are compared. Aliphatic fatty acids, especially octadecanoic acid were used as additives. The greatest viscosity reduction was found in polyethylene/(carbon black) and polystyrene/(calcium carbonate) compounds. Smaller effects are found with the other polyethylene/filler compounds and none in polystyrene/filler compounds. Contact angle experiments indicated carboxylic acid layers on the die surfaces for the polyethylene and not the polystyrene compounds. Mechanisms for this behavior are discussed.
Stretchability and Properties of LLDPE Blends for Biaxially Oriented Film
Authors: Uehara H. , Sakauchi K. , Kanai T. , Yamada T. 
Published: December 2013

Abstract
In order to improve the stretchability of linear low density polyethylene (LLDPE) for double bubble tubular film (DBTF), the blending of LLDPEs have been investigated. Three LLDPEs of varying densities were blended, and several films having different densities, molecular-weight distributions and composition distributions were produced. The stretchability and properties of these films were investigated and the relationship between the stretchability and the material properties were also discussed. The material properties of LLDPE which showed better stretchability were reported. Furthermore, the stretchability of LLDPE by using the laboratory tenter stretched film (LTSF) and the DBTF were compared. The prediction of the stretchability for the DBTF by using the LTSF was reported.
Experimental Investigation of the Development of Interfacial Instabilities in Two Layer Coextrusion Dies
Authors: Valette R. , Laure P. , Demay Y. , Agassant J.-F. 
Published: December 2013

Abstract
The stability of two-layer flow of polyethylene and polystyrene is experimentally studied in different flow geometries and for various flow rate ratios. A first coextrusion device allows to stop the coextrusion flow in a very long slit channel, to cool down the polymer sample and to dismantle the die in order to extract extrudate which is then carefully analyzed.
A second device allows to observe the whole slit flow through transparent lateral walls and to record the interfacial waves in both spontaneous and controlled unstable conditions.
Both devices point clearly out that the interfacial defect begins to grow after a specific flow distance and is then quickly amplified. This demonstrates the convective character of interfacial wave. Controlled unstable processing conditions in transparent die allow to measure accurately growth rate of defect in the linear regime and show quick occurrence of non linear regime.