bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
The Effect of Miscibility on Rheological and Mechanical Properties of PCL/SAN Blends
Authors: Keyzlarová L. , Sáha P. 
Published: December 2013

Abstract
Earlier, poly(∊-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) were found to be miscible on molecular level at 8 up to 28 wt.% of acrylonitrile (AN) in SAN copolymer [1]. The combination of PCL and different copolymers of SAN thus offers an opportunity to investigate the effect of miscibility on some key properties of the blends, e.g. rheological or mechanical. In this paper blends containing SAN with 25 wt.% of AN (miscible SAN-25) and 35 wt.% of AN (immiscible SAN-35) were used for this purpose.
Blends of PCL with various contents of SANs up to 40 wt.% were prepared by melt mixing in a Brabender laboratory mixer. The miscibility of the mixed PCL/SAN blends was investigated by differential scanning calorimetry (DSC). The blends rheological characteristics were determined on a Rheoflixer capillary rheometer at various temperatures. Rabinowitsch and Bagley corrections and the power-law relation were used. The extrudates were observed under a scanning electron microscope. In addition, mechanical testing was performed on a tensile testing machine.
It was found that blends of PCL with a minor amount of miscible SAN-25 provide a better balance of rheological and mechanical properties than those of pure PCL. The immiscible blend shows properties inferior to the miscible one. Immiscible SAN-35 increases viscosity, shear thinning and extrudate swell of PCL more than the miscible type. In contrast to the miscible blends containing SAN-25, which were without any form of unstable flow at shear rates of 10 to 10 000 s−1, melt fracture occurs in the immiscible blends with SAN-35. Positive synergism in tensile strength and elongation at break can be seen for 90/10 PCL/SAN-25 blend processed at 130°C. The addition up to 30 wt.% of SAN-25 miscible with PCL increases elongation at break.
Structuring of Interface-modified Polymer Blends
Authors: Lyngaae-Jørgensen J. 
Published: December 2013

Abstract
The paper treats the case where blends of polystyrene (PS), poly (dimethylsiloxane) (PDMS) and a diblock copolymer of PS and PDMS are used as model materials. This modelsystem is predicted to be “stable” in discrete blends in simple shear flow. Stable in the sence that the block copolymer can not be removed form the interface during simple shear flow.
A hypothesis stating that coalescence of drops may be subdued by “stable” diblock copolymer at the interfaces in 3D flows are tested with a Brabender mixing chamber. For well dispersed systems absence of coalescence would confine the occurrence of bicontinuous structures to a phase inversion point volume or prevent bicontinuous phase structure (IPS) formation all together.
Addition of PS-b-PDMS diblock copolymer do contract the volume fraction interval where IPS are found but a relatively broad interval is still observed. The phase inversion volume predicted by theory is outside the observed IPS interval for one of the investigated blend pairs.
Breakage and Buckling of Fibrous Reinforcements During Fabrication of Thermoplastic Matrix Composites
Authors: Cohen A. , Adams M. E. , Campbell G. A. 
Published: December 2013

Abstract
The paper addresses the buckling of fibrous reinforcements which occurs due to motion of the amorphous matrix material during solidification. The motion of the matrix material is caused by a variation in cooling rate in different portions of a composite while the sample is cooling. In the course of this study, samples were prepared with a fiber reinforcement sandwiched between premolded sheets of polycarbonate. Samples were either processed in a two-cavity, “dogbone” shape mold or in a rectangular, single-cavity mold matched die compression mold. In order to visualize the motion of the molten matrix material, strands of polycarbonate blended with carbon black were mounted into the matrix. The buckling behavior demonstrated sensitivity, to the amount of reinforcement observed with single and multiple filaments of carbon and Kevlar and bundles of carbon fiber tows. This paper provides scaling considerations indicating the sensitivity of the observed effects to processing conditions and concludes with a discussion of the implications for load carrying capabilities of composites.
Processing of Biodegradable Polymer Composites as A Drug Delivery System in Vitro
Authors: Liu S.-J. , Tsai C.-H. , Lin S.-S. , Ueng S. W.-N. 
Published: December 2013

Abstract
This report explores the alternative of processing biodegradable polymer-antibiotic composites as a long-term drug release. Polymer-antibiotic composite beads were manufactured by a compression-sintering technique. An elution method was employed to characterize the release rate of antibiotic over a 35-day period at 37°C. Biodegradable polymer composites released high concentrations of antibiotic (well above the breakpoint sensitivity concentration) in vitro for the period of time needed to treat bone infection; i.e. 4 to 6 weeks. By changing the processing variables, one is able to control the release rate of the beads. This provides advantages of meeting the specific antibiotic requirement for patients with various surgical infections.