bluuebunny/crossref_metadata_2025 huggingface dataset:
From Crankshafts to Bore Cores
Authors: Jenkins Barry M. , Vander Voort George F.
Published: December 2013

The field of quantitative microscopy (QM), as applied to base-metals, alloys and their products, is considered to be mature, sophisticated, and essential to the manufacturing industry. However, the role of QM in the mining sector is still developing. Compared to man-made metals and materials, natural structures such as ore bodies can be far more complex and varied, and difficult to characterize at the microstructural level. This has limited the scope of QM in petrography until recent times. Now, enormous possibilities have opened up due to the availability of powerful computers, automated microscopes, image analysis software and advanced process modelling techniques. In most mining applications, representative sampling and specimen preparation procedures for QM need to be far more rigorous than those familiar to metallographers. It is arguable that the success or failure at the industrial level of many new applications will depend on the development of practical methodologies to meet these high demands. This paper covers some of the challenges and pitfalls of automated petrography and some improvements in methodology developed with guidance from established standards in metallography.
Application of the Disector to Determine the Distribution of True Interlamellar Spacing in Lamellar Microstructures
Authors: Sankaran S. , Pathak Piyush , Sangal Sandeep , Padmanabhan K.A.
Published: December 2013

It is well known that the interlamellar spacing controls the mechanical properties of any material with a lamellar microstructure. It is also expected, although not yet established, that varying distribution of interlamellar spacing would also influence the properties. However, the problem of determining the distribution of interlamellar spacing from metallographic observations made on single 2D sections is almost intractable. A technique to estimate the true interlamellar spacing in a lamellar microstructure, using a 3D probe referred to as a disector, has been developed. This disector technique was used to obtain the distribution of true interlamellar spacing of pearlite in a microalloyed steel. The results indicate clearly that there is a significant variation of interlamellar spacing across pearlite colonies and also within individual colonies. In addition, it was possible to determine the overall distribution of interlamellar spacing.
Charakterisierung der Dispersität der Mikrostruktur von Wolframschmelzcarbiden
Authors: Böbe Alexander , Böbe Mario , Martinek Irmhild , Hübner Andrea
Published: December 2013

Kurzfassung

Zur quantitativen Abstufung der Gefügedispersität („Fiedrigkeit“) von blockigen Wolframschmelzcarbiden (WSC) wurde ein Linienschnittverfahren an lichtmikroskopischen Hellfeld-Aufnahmen reliefpolierter Carbidquerschnitte angewendet. Aufgrund des Formzusammenhanges im regellos orientierten Phasengemisch des WSC diente die aus je 15 Carbidorientierungen bestimmte, mittlere Schnittsegmentlänge der δ-WC Phasen zur Quantifizierung der Gefügedispersität. Eine Charakterisierung der Gefügequalität blockiger WSC-Pulver wird durch eine Auswertung von je 120 WSC-Teilchen ermöglicht. Die bislang verwendete, stark subjektive Methode des visuellen Vergleiches, kann durch die vorgestellte computergestützte Bewertung und Klassierung der „Fiedrigkeit“ von WSC ersetzt werden, um durch eine präzisere Carbidpulvercharakterisierung bereits von vornherein die Beschichtungsqualität besser vorhersagen zu können.
Implications of EBSD-based Grain Size Measurement on Structure-Property Correlations
Authors: Kral Milo V. , Drabble Daniel J. F. , Gardiner Benjamin R. , Tait Peter C.
Published: December 2013

Samples of annealed and cold rolled 70%Cu-30%Zn brass and 800H alloy were characterized using electron backscatter diffraction (EBSD) pattern analysis to determine average grain diameter, with the ability to differentiate between random high angle grain boundaries and annealing twin boundaries. Hardness measurements of both materials and minimum creep rates for the brass alloy were measured and compared to average grain diameter measurements, which had been calculated with twin boundaries both included and excluded (in accord with ASTM E 112). The present results indicate that annealing twin boundaries contribute to mechanical properties and therefore should be considered in structure-property correlations.
Application of the Digital Holographic Interference Microscopy for Thin Transparent Films Investigation
Authors: Tishko Dmitry Nikolayevich , Tishko Tatyana Vasilyevna , Titar Vladimir Petrovich
Published: December 2013

In this work the digital holographic interference microscope (DHIM) is proposed for investigation of thin transparent films on transparent substrates. The DHIM allows 3D imaging of surfaces of thin transparent films, and measurement of their geometrical parameters (thicknesses, sizes of defects). The method of the holographic interferometry, and the optical layout of the DHIM are described. The experimental results of investigation of thin AlN coatings on acryl substrates are presented.
Austenitkorngröße in sintergehärteten pulvermetallurgischen Stählen
Authors: Dlapka Magdalena , Strobl Susanne , Danninger Herbert , Gierl Christian
Published: December 2013

Kurzfassung

Für schmelzmetallurgische Stähle ist seit langem bekannt, dass die Austenitkorngröße einen entscheidenden Einfluss auf die mechanischen Eigenschaften hat. Besonders eine Austenitisierungsbehandlung, bei der für lange Zeit auf hoher Temperatur gehalten wird, kann ein dramatisches Kornwachstum bewirken, das die Bildung von Restaustenit fördert und in schlechten mechanischen Eigenschaften resultiert.
Zur Charakterisierung von flüssigmetallinduzierten Rissen beim Feuerverzinken von Baustahl durch unterschiedliche Ätztechniken
Authors: Durst Angela , Luithle Alexander , Bleck Wolfgang , Pohl Michael
Published: December 2013

Kurzfassung

Das Feuerverzinken von Stahlträgern gilt im Stahlbau als wirtschaftliche Möglichkeit den Stahl vor Korrosion zu schützen. Die Anforderungen an die Zinkschicht haben sich im Laufe der Jahre erweitert, so dass durch Variation der Zinkbadzusammensetzung die Schichtdicken verringert sowie das Aussehen der Zinkoberfläche verbessert wurde. Jedoch mehrten sich Schadensfälle an feuerverzinkten Konstruktionen in den letzten Jahren, die auf die flüssigmetallinduzierte Spannungsrisskorrosion zurückzuführen waren. Im Zuge von Untersuchungen an schadhaften Bauteilen stellte sich die Schliffpräparation von Zinkschichten auf dem Strukturwerkstoff Stahl als anspruchsvoll heraus. Hintergrund ist der kathodische Schutz des Eisens durch Zink bei Anwesenheit eines Elektrolyten. Diese Schutzwirkung führt bei der Ätzung von Stahlproben mit verzinkter Oberfläche dazu, dass die Zinkschicht stark angeätzt wird, jedoch der daneben befindliche Grundwerkstoff keine Gefügeentwicklung zeigt. Im Folgenden werden zwei Ätzverfahren vorgestellt, mit denen es möglich ist, sowohl die Zinkschicht als auch den Grundwerkstoff strukturiert darzustellen.
Untersuchung verschiedener Verfahren der Probenentnahme für die Wasserstoffanalyse bei Kaltwalzenschäden
Authors: Merzlikin Sergiy V. , Hassel Achim Walter , Steinhoff Karl , Wildau Monika
Published: December 2013

Kurzfassung

Beim Kaltwalzen ist seit langem eine typische Art von Ausschalungsbrüchen der Walzen bekannt. Es wird angenommen, dass eine Wasserstoffversprödung der gehärteten Walzen für die Schäden verantwortlich ist. Atomarer Wasserstoff kann beim Walzvorgang durch eine galvanische oder eine chemische Reaktion entstehen und in die Walze eindringen.

Bei jedem Verdacht auf wasserstoffinduzierten Walzenbruch muss der gesamte Wasserstoffgehalt bestimmt werden, um die Ursache des Schadens genau festzustellen. In dieser Arbeit wurde die Abhängigkeit der Ergebnisse der Wasserstoffanalysen von den jeweiligen Probenentnahmeverfahren untersucht, um dadurch mögliche Verfälschungen auszuschließen und eine Richtlinie für diese Prozedur für die Zukunft zu erarbeiten.
Influence of Surface Quality on the Biaxial Strength of Silicon Nitride Specimens
Authors: Harrer W. , Danzer R. , Supancic P.
Published: December 2013

Details of surface finish affect significantly the surface quality of ceramic specimens (e.g. surface roughness, residual stress). To analyse the influence of surface quality on strength five samples of silicon nitride specimens were machined applying different surface finishing procedures. Then they were strength tested using the biaxial Ball-on-three Balls (B3B) test. The test results were compared to those of conventional bending tests. A fractographic analysis was performed on selected specimens to identify the fracture origins. It could be shown that a better surface quality leads to an increased strength but increases the scatter of strength data too.
Defects and Fracture Statistics in Low-Pressure Injection Moulded Alumina Components
Authors: Lube T. , Kraleva I.
Published: December 2013

The strength and the defects responsible for failure occurring in tubular alumina components were investigated. Strength testing was performed on machined components in 3-point and 4-point bending. Weibull statistics were applied to describe the strength distributions. Fracture surfaces were investigated using stereo-microscopy and SEM. Fractography revealed that three different types of defects were responsible for failure of the 3-point as well as the 4-point bend specimens. Using an iterative procedure, a separate Weibull distribution for each defect type was evaluated using the data of the two different specimen types.
Microstructural Changes during Vacuum Carburizing of Steels
Authors: Bruncko Mihael , Anzel Ivan , Kneissl Albert C.
Published: December 2013

Vacuum carburizing is a modern, very efficient and environmentally friendly process for case hardening of steels. Nowadays the technology has replaced atmosphere carburizing in many cases due to better repeatability and uniformity of heat treated samples. The process of vacuum carburizing is performed under oxygen free hydrocarbon gas atmosphere (usually pure acetylene) at partial pressure lower than 20mbar and in conditions which are far from thermodynamic equilibrium. The process consists of the cycles of active (saturation) and passive (diffusion) stages. Desired case depth and corresponding target concentration profile of carbon can be supervised by controlling the duration of these two stages.
A New Tint to Obtain Coloured Metallographic Structures of Tempered Cast Iron, Carbon Steel and Alloys
Authors: Sánchez L. García , Dietz C. , Valenzuela F. Penco , García J. A. Martínez , Portal A. J. Criado
Published: December 2013

A new method for preparation of metallographic samples, based on application of phthalocyanine blue diluted with nitrocellulose resin, is presented. A thin layer of the dye was applied onto cast iron or carbon steel samples and alloys prior to observation under optical microscopy. Highly resolved coloured micrographs were obtained for quenching structures or isothermal phase transformation of carbon iron alloys.
Evaluation of Diffusion Bonding (Welding) Process Temperatures of AISI 1010 Plain Carbon Steel with AISI 430 Ferritic and AISI 420 Martensitic Stainless Steels
Authors: Çay V.
Published: December 2013

Characterization and evaluation of diffusion bonding process temperatures of AISI 1010 plain carbon steel (PCS) with AISI 430 ferritic and AISI 420 martensitic stainless steels were experimentally studied. The diffusion bonding of AISI 1010 with AISI 430/420 steel couples were held for 40 min, at 800°C–900°C–1000°C– 1100°C, under protective atmosphere, with 10 MPa load blow those that would cause macroscopic deformation to the contacting surfaces. Microstructure morphologic evaluations were carried out with the help of SEM. Shear tests and weld efficiency were calculated at interface for mechanical properties characterization. Test results and morphologic evaluations showed that under given diffusion bonding conditions, welding/bonding integrity were slightly increased at elevated temperatures and highest values were traced at 1000°–1100°C process temperatures.
Analysis of the Crack Initiation at Non-Metallic Inclusions in High-Strength Steels
Authors: Grad P. , Reuscher B. , Brodyanski A. , Kopnarski M. , Kerscher E.
Published: December 2013

High-strength steels exhibit different fracture surface characteristics under cyclic load when failure is initiated by non-metallic inclusions depending on the lifespan. These can be attributed to different crack propagation mechanisms. These characteristics are correlated with the short and long crack propagation. As far as the short crack is concerned, the mechanism of the discontinous decohesion of carbides in the immediate vicinity of the inclusions and the merging of the resulting microcracks to form a macrocrack is discussed. This postulated mechanism is investigated by means of a combination of scanning electron microscope (SEM) analyses of the fracture surface and target preparation by means of focused ion beam (FIB) by a detailed resolution of the local microstructure around the crack-initiating inclusion and the crack path.
The Kinetics of Individual Grains in Polycrystalline Materials
Authors: Zöllner D. , Streitenberger P. , Fielden I.
Published: December 2013

Based on a mean-field approach a 3D grain growth model is presented which predicts the growth history of individual grains of a grain ensemble in terms of linear grain size and time. The analytical results are compared with the results of numerical simulations using the Monte-Carlo-Potts model. In addition, based on a stochastic model of grain growth, the diffusivity of the very discontinuous movements of individual quadruple and triple junctions is set in relation to the rate of growth. This allows the calculation of the average growth law of an ensemble of grains solely from the measurement of the stochastic growth kinetics of individual grains. The results from simulation and theory are compared with experimental results of in-situ scanning electron microscopy observations of grain growth in polycrystalline metals.
Analysis and 3D-Modelling of Open-Pore Metal Foams Using Binarized Light-Optical Microscopy In-Depth Microsections
Authors: Matz A. M. , Jost N.
Published: December 2013

Open-porous metal foams are cellular structures that can be defined, in simplified terms, as interwoven networks of metal ligaments that are surrounded by a fluid (liquid or gaseous). They are characterized by a very low relative density of usually 4 to 12% of the density of a solid composed of an identical base material. As such they have a small volume along with a very large surface area, providing for numerous interesting physical properties with resulting practical applications.

A detailed description of the physical properties of these materials essentially requires a characterization of their geometric structure. Within the scope of this work, microsections of these foam structures are captured in a defined depth distance of sz
≤0,5 mm. In the course of the experiment, these microsections are software-converted to binary images. They are optimized in a way that artifact characteristics, which would have a negative effect on the analysis, converge to a minimum. Based hereon, it is now possible to generate realistic 3D models of individual microsections, allowing for a three-dimensional measurement of the material. Furthermore, binary format microsections allow for determining miscellaneous statistical characteristic values of the examined foam structures. Based on these results, it is consequently very easy to draw conclusions on the geometry of large-dimensional foam structures. When varying individual characteristic parameters, such a database also provides the possibility to generate differing geometric structures, which, in turn, provide for a sound basis in order to create scalable simulation models.
Liquid Metal Induced Crack Formation in Molten Zinc – a Damage Mechanism Driven by Diffusion and Stress
Authors: Körber D. , Landgrebe R. , Adelmann J. , Hoche H. , Oechsner M.
Published: December 2013

Tests have been performed on hot-dip galvanized four point bend specimens to investigate how different levels of compressive stresses and tensile loads under simultaneous thermal activation below the melting temperature of the zinc coatings affect liquid metal assisted cracking (LMAC). While the material volumes under tensile stress developed intergranular cracking, areas under compressive stress – even using a tin and lead alloyed zinc melt – did show no signs of damage. The flat specimens tested without superimposed loading did only show intergranular edge defects in the order of several grain layers when ageing during several hours in differently alloyed zinc melts. Moreover, in the context of the tests, the dominating effect of the alloying elements lead and tin could be confirmed for the intergranular crack formation. Furthermore, the particular importance of the material condition for the occurrence of the damage by LMAC could be shown by means of the progression of the crack formation in the microstructure.
Microstructural Characterization of Carbides in a Cast High-Speed Steel Using Different Metallographic Techniques
Authors: Gümüş S. , Atapek Ş. H. , Polat Ş. , Erişir E. , Alkan A.
Published: December 2013

High-speed steels are mostly manufactured by casting and they exhibit a characteristic dendritic microstructure with primary carbides. In this study, the morphology of carbides in a cast high-speed steel is investigated using light and scanning electron microscopes. The morphology and structure of the carbides were revealed by means of different metallographic techniques such as chemical and electrolytic etching and color metallography. The combination of these metallographic techniques gives different approaches to how different primary carbide morphologies can be observed in the martensitic structure. Besides, microanalysis was carried out to determine the chemical composition of primary carbides using SEM/EDX.
Moving Blade Failure in the Low-Pressure Turbine of a Steam Turbo Set
Authors: Mundt G. , Neidel A. , Matijasevic-Lux B.
Published: December 2013

The rivet spigots by means of which the shroud bands of steam turbine vanes are attached to the blades failed because of corrosion fatigue cracking. The result was that the blades underwent increased dynamic stresses and, consequently, sustained fracture by cyclic loading.
Grain Size Measurements Using Circular or Rectangular Test Grids
Authors: Voort G.F. Vander
Published: December 2013

Experiments were conducted to determine the influence of the number of grains counted using the Jeffries planimetric procedure of ASTM E 112 with a single test circle compared to the number counted using rectangles as suggested by Saltykov. Both planimetric methods produced similar estimates of the ASTM grain size number when the counts per field placement were high. The Saltykov rectangle method is a viable test method and produced good data down to low count numbers. Bias was not observed at low counts, only data scatter. The intercept count method, using only a single test circle per field, yielded slightly higher estimates of the ASTM grain size number, but the difference was relatively insignificant.
The Quantitative Metallographical Characterisation of Hot Formed Duplex Steels
Authors: Weidig C. , Schepanski N. , Rettenmayr M.
Published: December 2013

Image analysis investigations into the quantitative characterisation of hot formed duplex steel microstructures are presented. The shape parameters Feret diameter, Feret angle and roundness are used to describe the morphology of the microstructures. High temperature compression tests were carried out at 1 150 °C, 1 200 °C and 1 250 °C and the microstructures produced compared with that of the initial un-deformed material. The technical yield strength were also correlated with the temperatures and strain rate used. This revealed that the technical yield strength doubled by reducing the temperature of deformation from 1 250 °C to 1 150 °C and by increasing the strain rate by an order of magnitude. It is also shown that the pronounced preferential direction of the phases present in the initial un-deformed material is no longer quantitatively discernable above a temperature of deformation of 1 200 °C.
Growth Kinetics of CrC Coating Layers on AISI D3 Obtained by Thermo-Reactive Diffusion Technique
Authors: Kurt B. , Onder E. , Carboga C. , Demirel B. , Karagoz M.
Published: December 2013

In this study, the characterization and growth kinetics of chromium carbide layer coated on AISI D3 cold-work tool steel by pack method thermo-reactive diffusion process in solid medium were carried out. Coatings were performed by using ferro-chromium powder as Cr source at 950, 1 000, 1 050 and 1 100 °C for 2 and 4 h. The carbide layers were evaluated based on microstructure, thickness, hardness, energy dispersive X-ray facility and X-ray diffraction analysis. Chromium carbide layer thickness on the coated specimens has been in the 4.2–17 μm range depending on treatment time and temperature. Growth kinetics of the carbide layers were analyzed by measuring the depth of carbide layer as a function of temperature and time. The activation energy was estimated to be 180.13 kJ/mol. The microhardness values of the coating layers are range of 1 200–1 600 HV. Ball rotating micro-abrasion technique was used to carry out wear tests on the thin coating layers.
Quality Control of Thermal Spray Coatings in Diesel Engines
Authors: Carstensen J. V. , Lindegren M.
Published: December 2013

Thermal spraying is a method, which is suitable for coating of large components. The coatings can e. g. improve the wear, friction and/or corrosion properties of components so that they can withstand the increased loads. The quality of the coatings is essential to ensure reliable operation of the components. However, quality control of thermally sprayed coatings is indeed nontrivial and sample preparation is a key issue. This paper shows examples of thermal spray coated components in large diesel engines and provides insight into the methods used in preparing samples for quality control.
Influence of Viscosity-interface Modifier Interactions on Performance and Processability of Rice Hull PE Composites
Authors: Dixit N. , Sain M. , Kortschott M. T. , Gulati D.
Published: December 2013

Interface modifiers and viscosity modifiers are added to wood plastic composites to improve interfacial adhesion and processing rate respectively. However, because of the chemically reactive nature of interface modifiers and viscosity modifiers, there is a high possibility of interactions between them, influencing the mechanical properties and processabilty of the composites. To evaluate this point, interactions between three different interface modifiers and a viscosity modifier were investigated in this study. Concurrently, the effectiveness of three different interface modifiers in improving mechanical properties of the composites was also studied. The results indicated that there was a significant improvement in the tensile strength, flexural strength, flexural modulus and impact properties of the composites with all the three maleated polyethylene based coupling agents. Moreover, presence of an amide carboxylic acid based viscosity modifier along with a maleated polyolefin based interface modifier reduced the mechanical properties of the composites as compared with that of the composites having only maleated polyolefin based interface modifiers.
Single and Multi Objective Optimization for Injection Molding Using Numerical Simulation with Surrogate Models and Genetic Algorithms
Authors: Zhou J. , Turng L.-S. , Kramschuster A.
Published: December 2013

The objective of this study is to develop an integrated computer-aided engineering (CAE) optimization system that can quickly and intelligently determine the optimal process conditions for injection molding. This study employs support vector regression (SVR) to establish the surrogate model based on executions of three-dimensional (3D) simulation for a selected dataset using the latin hypercube sampling (LHS) technique. Once the surrogate model can satisfactorily capture the characteristics of simulations with much less computing resources, a hybrid optimization genetic algorithm (GA) or a multi-objective optimization GA is then used to evaluate the surrogate model to search the global optimal solutions for the single or multiple objectives, respectively. The performance and capabilities of other surrogate modeling approaches, such as polynomial regression (PR) and artificial neural network (ANN), are also investigated in terms of accuracy, robustness, efficiency, and requirements for training samples. Experimental validations and applications of this work for process optimization of a special box mold and a precision optical lens are presented.
Correlations between Injection Molding Parameters, Morphology and Mechanical Properties of PPS Using Artificial Neural Networks
Authors: Lotti C. , Bretas R. E. S.
Published: December 2013

The processing conditions of injection molding have a complex influence on the morphology and on the mechanical properties of a semicrystalline polymer. Therefore, to establish correlations between processing conditions, morphology and mechanical properties constitutes a difficult task; finding these correlations is one of the goals of a materials engineer.

The purpose of this work was to study the influence of the injection molding conditions on the morphology and mechanical properties of poly(p-phenylene sulphide), PPS, using artificial neural networks, ANNs. First, a statistical analysis was done to find the more influential processing parameters that affect the morphology and mechanical properties of the PPS. Second, ANNs were applied to establish correlations between processing conditions, morphology and properties.

It was found that the variables with the highest influence on the morphology and the mechanical properties were the injection and mold temperatures (Tinj and Tmold, respectively), as they showed a straight relationship with the crystallinity index of the injection molded part.

Three different ANNs were built to predict the correlations. The ANN-1 predicted the crystallinity gradient along the thickness of the injection molded part from Tmold, Tinj, and flow rate, Q; the ANN-2 predicted the elastic and flexural modulus, E, and the yield stress from the crystallinity gradient, while the ANN-3 predicted the mechanical properties directly from the processing conditions. All ANNs were built with only fifteen experimental data and were trained with the group cross-validation method, GCV and with a training-test set method. Both methods showed similar and excellent performance. Thus, it can be concluded that ANNs can be used as a powerful tool in the learning of these complex correlations.
Tip-clearance Effect on Mixing Performance of Twin Screw Extruders
Authors: Ishikawa T. , Nagano F. , Kajiwara T. , Funatsu K.
Published: December 2013

In order to evaluate the tip-clearance effect on mixing, 3-D numerical simulations were applied to kneading block section of co-rotating twin screw extruders. The software we used was originally developed for non-Newtonian and non-isothermal flow analysis based on the finite element technique. The marker-particle tracking analysis was also developed in order to estimate the particle path, residence time distribution, stress and strain history, and so on.

The stress distribution obtained by the above-mentioned simulations suggested the following mixing mechanisms. The kneading block with the small tip-clearance (TC) caused the bimodal stress distribution which had peaks in both high and low stress level. The marker-particles which overpassed the TC formed the peak at the high stress level and the other particles contributed to the peak at the low stress level. In other words, a large number of particles evaded the TC and it caused heterogeneous stress induced mixing. On the other hand, the large tip-clearance caused the narrow and sharp stress distribution because most of the particles passed over the TC. The stress level was not high, however, homogeneous stress induced mixing was expected. Since the tip-clearance applied a significant effect to the dispersive mixing, it should be optimised in accordance with the material design.
Effects of Take-up Speed of Melt Spinning on the Structure and Mechanical Propertiesof Maximally Laser Drawn PA9-T Fibers
Authors: Uddin A. J. , Ohkoshi Y. , Gotoh Y. , Nagura M. , Endo R. , Hara T.
Published: December 2013

A new semiaromatic polyamide, PA9-T, was melt-spun at take-up speeds from 200 to 1000m min−1. The as-spun fibers were drawn with CO2 laser-heated drawing to their maximal draw ratio (DRmax). The drawing stress was recorded during this process. The effects of take-up speed of melt-spinning on maximally drawn fibers were characterized through measurements of density, birefringence, wide-angle X-ray diffraction, crystal orientation, tensile testing, and dynamic viscoelastic analysis. All as-spun fibers were essentially amorphous and their birefringence and density increased slightly with the increase of take-up speed. Lower take-up speeds yielded higher DRmax values, and fibers drawn to their DRmax exhibited superior structure and mechanical properties. The tensile strength and Young's modulus achieved were the highest reported to date for PA9-T: 737 MPa and 5.8 GPa, respectively.
Study of Starch Gelatinization in a Flow Field Using Simultaneous Rheometric Data Collection and Microscopic Observation
Authors: Yu L. , Kealy T. , Chen P.
Published: December 2013

Gelatinisation of aqueous cornstarch dispersions with different amylose/amylopectin ratios were studied with respect to their response to the simultaneous application of thermal and mechanical stresses. The study was conducted using a combined controlled stress (CS) rheometer and microscope with camera, allowing variations of viscosity and microstructure to be recorded concurrently. The microscopic images were recorded by the camera, one image for each rheological data point. It is the first time a direct relationship between viscosity and physical variation of starch granules in dispersion has been established and directly optically observed for starch gelatinisation in the presence of an applied shear field. It was found that there are two steps for starch gelatinisation under these conditions with regard to the physical transition of the starch granules: (1) starch swelling and gradual dissolving and leaching of starch components; (2) rapid dissolution of a high proportion of the granule. In the first step the viscosity increaseed gradually, as the starch granule was slowly dissolved and materials were leached into the water carrier. The granules became almost transparent in the presence of the applied thermal and mechanical fields and dimensional changes in the starch granules (swelling) during the latter stages of gelatinisation can not be clearly observed. In the second step, the starch granule disappeared in a short time and viscosity of the aqueous material increased sharply. The gelatinisation temperature under shear stress, as measured by the CS rheometer/microscope combination is lower than that measured by Differential Scanning Calorimetry (DSC) under shear-less conditions.
Analysis of the Residual Stresses in the Process of Nanoimprint Lithography
Authors: Young W.-B.
Published: December 2013

Nanoimprint lithography has attracted broad interest as a low cost method to define nanometer scale patterns in recent years. In the cooling stage of the nanoimprint lithography process, the polymer resist is constrained inside the tool. As the temperature decreases, the polymer may shrink away from the tool. However, due to the constraint of the tool, thermal stresses may be induced in the polymer while the relaxation effect tends to release the build up of the stress level at the same time. In this study, a visco-elastic model was developed to analyze the stress variations of the imprinted patterns during the cooling process. Most of the residual stress is found to concentrate on the interface between the polymer resist and the substrate. Also, some stress concentration areas are observed near the adjacent of the large un-patterned area and the pillar. Thermal stress above the glass transition point is demonstrated to be able to relax during the cooling process. Most of the residual stresses are induced at the cooling stage with a temperature lower than the glass transition point.
Numerical Simulation of Viscous Flow in a Partially filled Co-rotating Twin Screw Extruder
Authors: Pokriefke G.
Published: December 2013

The free-surface flow of fully melted material in the conveying section of a co-rotating twin screw extruder has been simulated numerically with the Finite Volume Method and an Eulerian multiphase model. In this model the interface is captured in an implicit manner with the help of the local volume fraction in a cell.

The results presented here reveal the power and conveying characteristics of the twin screw configuration. Some interesting findings are discussed for the power characteristic in the fully filled state as well. The flow field and derived quantities are discussed with regards to the axial transport, symmetries in the flow field and locations of high energy dissipation. All results are compared to the fully filled state.

Additionally, a new term, the volume flux based “conveying degree”, is introduced in this paper. The difference to the volume-based degree of fill is pointed out.
Effects of Cavity Conditions on Transcription Molding of Microscale Prism Patterns Using Ultra-High-Speed Injection Molding
Authors: Han X. , Yokoi H. , Takahashi T.
Published: December 2013

Ultra-high-speed injection molding has been reported to be a very effective method for improving transcription molding. In this study, by using stampers with V-grooves having pitches of 25 μm and 100 μm, we investigated the effects of cavity conditions, including cavity thickness, groove layout, and groove pitch size, on transcription molding. These experiments were also conducted under various molding conditions such as injection rates, melt and mold temperatures, and holding pressure, etc. As a result, it was found that the groove layout of a stamper remarkably affects transcription fidelity and these effects do not disappear when the molding is performed with a cavity-vacuum process. This phenomenon was explained using the well-known molecular orientation by the extensional flow during injection molding. When transcription molding was performed with cavities of different thicknesses (0.5 mm, 1.0 mm, and 2.0 mm), the effect of holding pressure on transcription was inversely related to the cavity wall thickness. This result indicates that, in the molding with a thin cavity wall, the transcription mainly completed during the filling stage. In addition to the shortening of cavity filling time and decrease in viscosity by shear heating, an accelerated increase in cavity pressure during the cavity filling stage was also found to be important for explaining the improvement in transcription with ultrahigh-speed injection molding.
Effect of Melt and Mold Temperature on Fiber Orientation during Flow in Injection Molding of Reinforced Plastics
Authors: Shokri P. , Bhatnagar N.
Published: December 2013

Injection molding, a highly productive manufacturing process, is one of the most versatile production methods in plastic manufacturing industry. It is capable of producing intricate net shapes without requiring finishing treatment and with good dimensional accuracy. In injection molding of reinforced thermoplastics the properties of the final product highly depend on the state of fiber orientation. Tailoring the fiber orientation in the final product, in order to control the properties, is the basic motivation of this study. Among different parameters, which could affect the orientation patterns, this study is concerned on analyzing the effects of mold and melt temperature on the state of fiber orientation during flow. In contrast to the melt temperature, which has a limited range for variation, mold temperature provides wide range of possible input at different locations such that by revealing its effect it could become one of the most attractive parameters in controlling the properties of injection molded fiber reinforced thermoplastic products.
Stretchability and Properties of Biaxially Oriented Polypropylene Film
Authors: Kanai T. , Uehara H. , Sakauchi K. , Yamada T.
Published: December 2013

The double bubble tubular film (DBTF) process is a more economical way of producing biaxially oriented film, when compared to the tenter biaxially oriented film process. This film manufacturing technique has been widely used to produce biaxially oriented films because of good shrinkability and high physical properties. Recently, shrinkage film for this usage is required to have good stretchability and shrinkage strength. But the biaxial stretchability changes of polypropylenes and the reasons for such have not been reported upon systematically.

In this report, the relationship between stretchability and material design of various polypropylenes (PP) for biaxially oriented film, which are most popular polymers, was investigated. Several different ethylene contents and melt flow indices (MI) of PP were examined. There was a correlation between MI, ethylene content and the stretchability of the DBTF. A random copolymer with MI 2 g/10 min and ethylene content 4.0 wt.% gave good stretchability. The most suitable composition distribution for stretching and the properties of biaxially oriented films were studied by using the temperature rising elution fractionation.
Simulation of 3D Crystallization of Colloidal Nanoparticles on a Substrate during Drying
Authors: Fujita M. , Yamaguchi Y.
Published: December 2013

This paper presents a simulation of 3D crystallization of colloidal nanoparticles on a substrate during drying. The translational motion and the rotational motion of nanoparticles are modeled by Langevin equation and the law of angular momentum conservation, respectively. Contact force, capillary force, Brownian force, van der Waals force, electrostatic force and fluid drag force are taken into consideration. The drying of colloid is expressed as a decrease of the colloid thickness with time. The drying process of a water solution of polystyrene nanoparticles on a flat substrate is investigated, so that a self-ordered 3D crystal of polystyrene nanoparticles is formed after drying. The crystallization is visualized with time, and vertical and planar structures of nanoparticles are evaluated temporally and quantitatively. The result indicates the primary mechanism of 3D crystallization of colloidal nanoparticles during drying, in which both layering in the vertical direction and planar crystallization take place at the same time.
Dynamically Vulcanized Nanocomposite Thermoplastic Elastomers Based on EPDM/PP (Rheology & Morphology)
Authors: Naderi G. , Lafleur P. G. , Dubois C.
Published: December 2013

This study examines the rheological and morphological properties of dynamically vulcanized nanocomposite thermoplastic elastomers (TPV nanocomposites) based on PP/EPDM. Rubber contents of 20, 40, and 60% were used with polypropylene of different viscosities at 2 wt.% of nanoclay. We performed rheological and morphological characterizations on the nanocomposites using X-ray diffraction, transmission electron microscopy, scanning electron microscopy and rheometry in small amplitude oscillatory shear. The effects of polypropylene viscosity, maleic anhydride grafted polypropylene (PPMA), and composition were also investigated. The storage modulus (G) of the TPV nanocomposites (without PPMA) containing 20, 40, and 60% rubber significantly increased in comparison with similar but unfilled samples and also a further increase in the G from the incorporation of the PPMA in the samples. The agglomeration of the clay considerably decreased when the rubber content was increased in the TPV nanocomposites. The yield stress of the prepared TPV nanocomposite, based on a low-viscosity PP, increased more than that of the sample from high viscosity PP. The TPV nanocomposites containing 20, 40 and 60% EPDM exhibited a strong elastic modulus that tended to level off (plateau) at low shear rates. These results were attributed to strong interfacial interactions between the nanoclay and TPV matrix and, also, the existence of the physical three-dimensional network structure formed between the cured rubber particles, as evidenced by the morphological features of the samples. A Carreau-Yasuda law with yield stress and a linear viscoelastic model, taking into account the maximum packing volume () were used to describe the melt linear viscoelastic properties of the TPV nanocomposites.
Polymer Processing Problems from Non-Rheological Causes1
Authors: Nakajima N.
Published: December 2013

There are a variety of problems in polymer processing. In this paper those problems which arise from non-rheological causes are described. The examples were taken from the period from 1960 to 1970's. Even though remedial steps were taken at the time when problems occurred, similar problems may occur in the future. The problems are well-known among those who worked in the area, but may not be known widely, because very few have ever been published.

Some of the problems may be eliminated in the course of improving polymerization and fabrication (processing) techniques. Some problem-solving will become easier with the improvement of sensitivity of analytical techniques. Some problems merit further scientific studies. Many problems provide seeds for inventions.
Modelling of Capillary Rheometer Data and Extrapolation of the Viscosity Function into the Linear Viscoelastic Region
Authors: Göttfert A. , Reher E. O. , Balagula I. M.
Published: December 2013

3- and 4 parameter models (Carreau-Winter, Sabia, Yasuda) are used for fitting capillary rheometer tests. These fitted data are then compared with rotational visco-simeter test data in the region of small deformation speeds. The results clearly demonstrate that the extrapolated capillary rheometer data acc. to the Sabia and Yasuda models yield good practice-relevant results. A good correlation was achieved between the calculated “zero viscosity” and the mean molecular mass and between the model curvature parameters and the width of the molecular mass distribution. For quality assurance in laboratory rheometery and on-line rheometry these obtained good results are of high importance.
A Stiffness Criterion For Cooling Time Estimation
Authors: Xu H. , Kazmer D.
Published: December 2013

The cooling time of an injection molded part directly affects the production cost and efficiency. In order to accurately estimate the cooling time, it is necessary to define the ejection condition. One common criterion for part ejection is when the mean or maximal temperature is equal or less than an estimated ejection temperature, Te [1]. But in industrial practice, the ejection condition is determined by the part's deformation or warpage due to ejection forces and subsequent cooling [2]. This research uses a combination of experimental, analytical, and statistical methods to discuss different ejection criteria and their rationality, thereby developing a more effective criterion based on part stiffness. This stiffness criterion facilitates more accurate estimation of cooling time at early stages of product development. This knowledge will help the designer to improve the design and reduce the cost by increasing the production efficiency while simultaneously ensuring injection molded part quality.
Dynamic Performance of Single-Screws of Different Configurations
Authors: Wong A. C.-Y. , Liu T. , Lam J. C. M. , Zhu F.
Published: December 2013

A 45 mm diameter single-screw “transparent” extruder was employed for an investigation on the dynamic performance of screws of different configurations. The extruder had eight glass windows installed along the entire metal barrel which enabled visual observation to be easily made. It was demonstrated, with this extruder, that pressure profile appeared to be an important factor for screw performance such as throughput rate, residence time, mixing characteristics, break-up of solid-bed, etc. The full-flight screw had the lowest pressure profile among all the screws tested, and its performance was found to be generally inferior to that of the mixing screws. The Darnell and Mol solid plug flow theory was shown to be applicable only to the mixing screws for the solid flow behaviour in the entire solid conveying section. The secondary flight of the barrier screw was found to effectively suppress solid bed break-up, but only at low screw speed. A screw with a Maddock mixing device was found to have the highest throughput rate. Other findings were believed to be of practical significance in the screw design.
Blank Design and Fiber Orientation Distribution During Compression Molding of GMT
Authors: Zhang L. , Dai G.
Published: December 2013

Glass mat thermoplastics (GMT) have the superior property/price ratio, they can be used in many industrial aspects. In this paper, through a 100mm-deep mold, the glass mat distribution, fiber orientation and mechanical properties of the part were studied under different blank designs. In conclusion, (1) Blank design has effect on the mat distribution and fiber orientation, and finally on the mechanical properties of the part. To a part, there is an optimum blank design, which will not greatly decrease the mechanical properties of the sheets in the final part. (2) In compression molding, interlaminar slippage, blank ejection and resin solidification result in mat distribution and fiber orientation.
Tensile Damage in Ternary Melamine-Formaldehyde Composites
Authors: Hagstrand P.-O. , Rychwalski R. W.
Published: December 2013

A new ternary planar random fiber composite (PRFC) is studied. It is a discontinuous glass fiber-reinforced, alumina trihydrate (ATH)-filled, melamine-formaldehyde (MF)-based composite of high fire resistance. Composites were manufactured from a commercially available molding compound using a Chopped Strand Mat (CSM), and compared with other ones obtained by varying the composition. Also, a comparison is made for grades with a high content of ATH but with different fiber architectures, realized by replacing the CSM mat by a needled mat.

The amount and type of tensile damage is shown. An elastic-damage type parameter is discussed and used. In-situ Scanning Electron Microscopic (SEM) observations on polished surfaces of samples mounted in a tensile stage and subject to tensile load, and observations on as-obtained surfaces are made. Stress-strain behavior depending on damage is analyzed, and possibilities of improvement of mechanical properties are postulated.
Effect of Twin-Screw Extruder Design and Process Conditions on Ultrafine CaCO3 Dispersion into PP
Authors: Bories M. , Huneault M. A. , Lafleur P. G.
Published: December 2013

Highly filled calcium carbonate (CaCO3)/polypropylene (PP) blends were compounded using an intermeshing corotating twin-screw extruder. The effect of screw configuration, rotation speed, flow rate, filler feed port position and barrel temperature on dispersion of calcium carbonate into polypropylene was investigated. A method based on image analysis of optical transmission micrographs obtained from 25 micron thick films was found to be quick and reliable for evaluating the state of dispersion in the filled systems. The dispersion state affected the mechanical performance of the systems. In particular, falling weight and unnotched Izod impact resistance decreased significantly as dispersion got poorer. Mechanical properties were correlated with the relative volume concentration of agglomerates in the blend.