bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isothermal crystallization of isotactic polypropylene in dotriacontane. I: Effect of nucleating agent addition on overall crystallization kinetics
Authors: Lim Gordon B. A. , Lloyd Douglas R. 
Published: December 2004

AbstractThe overall isothermal crystallization kinetics for nucleated and non‐nucleated isotactic polypropylene (iPP)‐dotriacontane systems was investigated. Adipic acid was used as the nucleating agent. Half‐time was determined via differential scanning calorimetry as a function of the experimentally controlled variables dilution, crystallization temperature, and the addition of nucleating agent. The influence of these variables on crystallization mechanism and spherulitic structure, as implied by the Avrami analysis, was determined. The influence of these variables on fold surface energy was examined by the Lauritzen and Hoffman analysis.
Effect of adhesion on the fracture toughness of calcium carbonate–filled polypropylene
Authors: Jancar J. , Dibenedetto A. T. , Dianselmo A. 
Published: December 2004

AbstractThe effect of adhesion on the strain energy release rate (Gc) and Charpy notched impact strength (NIS) of calcium carbonate (CaCO3)‐filled polypropylene (PP) at room temperature is investigated over a wide interval of particulate filler volume fractions. The concentration dependence of Gc and NIS are discussed in terms of competition between the effects of increasing stiffness, decreasing effective matrix cross section, and the transition from a plane strain to a plane stress mode of failure. In all cases the plane stress and plane strain limits of the critical strain energy release rate for initiation of cracks were not affected by the presence of the filler and are the same as those for neat matrix. In the case of no adhesion between components, the size of the crack tip plastic zone increases with increasing filler volume fraction (vf) because of the reduction of the material yield strength. In the region 0 < vf < 0.12, there is a mixed mode of failure, and the measured value of Gc for crack initiation increases steadily as the sample cross section approaches a fully plane stress state. The reduction in yield strength also results in the increase in Gc for crack propagation as reflected by an increase in NIS. Above vf= 0.12, the specimen cross section is in a fully plane stress state, and further increase in filler volume fraction (decrease in matrix effective cross section) has the net effect of reducing both Gc and NIS. In the case of “perfect” adhesion, the yield strength increases only slightly with vf. In the region 0 < yr < 0.05 there is also a mixed mode of failure, but the increase in Gc is much less than that for the no‐adhesion case since the size of the plastic zone in front of the crack is much smaller. Above vf= 0.05, the combined effects of increasing stiffness, reduction of the size of the plastic zone, and decreasing matrix cross section dominate the behavior, causing a steady reduction in both Gc and NIS. Good agreement was found between experimental data and calculations based on fracture mechanics principles.
Properties of the interphase in ternary polymer composites
Authors: Schaefer K. U. , Theisen A. , Hess M. , Kosfeld R. 
Published: December 2004

AbstractTernary systems consisting of polypropylene (PP), ethylene‐propylene‐dieneterpolymer (EPDM) and different types of inorganic fillers (kaolin, BaSO4) have been investigated with respect to their mechanical behavior. On the basis of an Interphase model, it was possible using the modified van der Poel equation to describe the temperature dependence of the storage modulus G′(T) and the loss modulus G″(T). The interphase properties G′(T) and G″(T) could be calculated.
A personal computer software program for coathanger die simulation
Authors: Arpin B. , Lafleur P. G. , Sanschagrin B. 
Published: December 2004

AbstractA good extrusion die must distribute the polymer melt in the flow channel such that the material exits from the die with a uniform velocity and temperature. Coathanger dies are commonly used for the extrusion of plastic sheets and films. The die is usually provided with a straining bar allowing a regulation of the flowrate in the case of a poor design. But this, in turn, can affect temperature uniformity. Therefore, the design of coathanger die is a complex task which is mainly accomplished by trial and error in industry. Analyses of the flow in coathanger dies have been reported in the literature. Analytical and numerical approaches are used to solve this problem. The first one involves many simplifying assumptions: the most important ones being the unidirectional and isothermal flow of the polymer. Most numerical methods deal with a 2‐D geometry, but only a few of them have considered the non‐isothermal flow. A new model has been developed using a modified FAN method (Flow Analysis Network introduced by Tadmor) for the calculation of the 2‐D flow, coupled with a finite‐difference scheme for the calculation of temperature. The overall model can run on a PC with only a few minutes of calculation. Good agreement was obtained between experimental data and simulations.
In‐line optical monitoring of polymer injection molding
Authors: Bur Anthony J. , Wang Francis W. , Thomas Charles L. , Rose Joseph L. 
Published: December 2004

AbstractAn optical sensor, consisting of optical fibers to transmit light to and from the mold cavity, was constructed for the purpose of measuring the onset of polymer solidification during injection molding. The sensor was used to detect characteristic fluorescence radiation from a dye which had been doped into the resin at very low concentration. By measuring changes in fluorescence intensity it was possible to detect whether the state of the resin was liquid or solid. We observed that, as the resin cooled in the mold, the onset of solidification was indicated by highly characteristic and distinct changes in the fluorescence intensity/time profile. Application of the method involved the use of a calibration relationship between the fluorescence intensity and temperature of the doped polymer in order to determine the distict features which characterize the onset of solidification. Injection molding of a glass forming polymer (polystyrene) and a crystallizable polymer (polyethylene) was monitored by this technique.
Compatibilized linear low‐density polyethylene/isotactic polypropylene blends studied by positron annihilation lifetime spectroscopy
Authors: Flaris V. , Zipper M. D. , Simon G. P. , Hill A. J. 
Published: December 2004

AbstractPositron annihilation lifetime spectroscopy (PALS), capable of probing free volume, is used to study the effect of compatibilizer concentration, compatibilizer type, and the effect of blend processing on the morphology and properties of an immiscible linear low‐density polyethylene/polypropylene system. It is proposed that improvement of fracture toughness due to compatibilization can be attributed to the packing (and bonding) at interfaces. Improved interfacial packing and bonding result in lower free volume concentration than expected from component additivity, with a concomitant increase in plastic deformation on impact.
Chemically oxidized polypyrrole: Influence of the experimental conditions on its electrical conductivity and morphology
Authors: Chen X. , Issi J‐P. , Devaux J. , Billaud D. 
Published: December 2004

AbstractThe effect of synthesis conditions on the electrical conductivity and the morphology of a chemically oxidized polypyrrole was investigated. It was found that the electrical conductivity of polypyrrole was strongly dependent on the pyrrole/FeCl3 ratio, which controls the redox potential of the reaction medium. The reaction temperature and the reaction duration also influence the electrical conductivity of the polypyrrole. A considerable influence of the nature of the solvent used on the aggregation state of polypyrrole particles was demonstrated. Optimal experimental conditions are proposed.
In situ composite: Phenolphthalein polyethersulfone—thermotropic liquid crystalline polymer blends
Authors: Li Gang , Yin Jinghua , Li Binyao , Zhuang Guoqing , Yang Yuming , Nicolais L. 
Published: December 2004

AbstractPhase behavior, thermal, rheological and mechanical properties plus morphology have been studied for a binary polymer blend. The blend is phenolphthalein polyethersulfone (PES‐C) with a thermotropic liquid crystalline polymer (LCP), a condensation copolymer of p‐hydroxybenzoic acid with ethylene terephthalate (PHB‐PET). It was found that these two polymers from optically isotropic and homogeneous blends by means of a solvent casting method. The homogeneous blends undergo phase separation during heat treatment. However, melt mixed PES‐C/PHB‐PET blends were heterogeneous based upon DSC and DMA analysis and SEM examination. Addition of LCP in PES‐C resulted in a marked reduction of melt viscosity and thus improved processability. Compared to pure PES‐C, the charpy impact strength of the blend containing 2.5% LCP increased 2.5 times. Synergistic effects were also observed for the mechanical properties of blends containing < 10% LCP. Particulates, ribbons, and fibrils were found to be the typical morphological units of PHB‐PET in the PES‐C matrix, which depended upon the concentration of LCP and the processing conditions.
A study on interfacial adhesion of poly(vinylidene fluoride) with substrates in a multilayer structure
Authors: Whang Wha‐Tzong , Cheng Wen‐Hua 
Published: December 2004

AbstractThe peel force of a PVDF/3‐APS/Si joint and a PVDF/3‐APS/Al joint can reach the same level by treating the Si substrate with ⩾ 0.3% 3‐aminopropyltriethoxy silane (3‐APS) solution and treating the aluminum substrate with NH3 solution (pH 10.5) first and then with ⩾ 3% 3‐APS solution. Scanning electron micrographs show that the interfacial adhesion mechanisms of PVDF/3‐APS/Si joints and PVDF/3‐APS/Al joints are different. In the peel test, the PVDF [poly(vinylidene fluoride)] break surfaces from PVDF/3‐APS/Si joints reveal striations on the surface and less plastic deformation. The significant plastic deformation of the PVDF at the break surface may result from the deeper interpenetration of 3‐APS with PVDF in the PVDF/3‐APS/Al joint than in the PVDF/3‐APS/Si joint. The peel force of PVDF film/substrate joint depends on many factors: film thickness, peel rate, concentration of coupling agent, the treatment time of the coupling agent on the substrate, and the substrate pretreatment.
Image Analysis Procedures for Characterizing the Fractal Dimension of Fineparticles
Authors: Kaye Brian H. , Clark Garry G. , Leblanc John E. , Trottier Remi A. 
Published: December 2004

AbstractFractal geometry developed by Mandelbrot is finding many applications in the description of rugged fineparticles and fineparticle systems such as packed powder beds. In the earlier publications dealing with the fractal structure of fineparticle boundaries a great deal of the experimental work was carried out manually. This was time consuming and limited the amount of investigative work which could be undertaken in a given context. In this communication several algorithms for automating the evaluation of the fractal dimensions of rugged fineparticle boundaries by automated image analysis are explored. Comparative data generated by the various procedures are presented.
Analysis of the Inorganic Constituents of Particles on a Particle‐by‐Particle Basis using a Computerized SEM‐EDS System
Authors: Gomez Cesar O. , Austin Leonard G. 
Published: December 2004

AbstractThis paper is based on the development of the Moza‐Austin technique for characterizing thousands of coal particles by approximate analysis of the major inorganic constituents Ca, Al, Si, K, Na, Fe and S in each particle. The technique has sufficient sensitivity to work on small volumes, is fast enough to handle large number of particles within a reasonable period of time, and consists of scanning electron microscopy combined with energy dispersive x‐ray spectrometry (SEM‐EDS). A computerized SEM‐EDS system that allows the automated analysis of hundreds of particles per hour is described. The analysis is based on the location and tracing of exposed areas of particles embedded in a polished specimen, the selection of sampling points on the traced sections, the collection of an x‐ray spectrum from each sampled point for a defined period of time, and the processing of the x‐ray intensity to calculate point composition using ZAF corrections. Procedures for correcting for dead time, spectrum background, x‐ray detector efficiency and spectrum overlap are described. Problems and future work are discussed.
Size Separation of Particles from Aerosol Samples using Impactors and Cyclones
Authors: Büttner Helmut 
Published: December 2004

AbstractInvestigations are presented on particle separation in impactors, sampling cyclones and other precollectors. These devices are increasingly used for the characterization of particulate matter. Size selective samplers must be characterized by their grade efficiency curves. A new measuring procedure is presented, which permits the determination of the grade efficiency curves of various sampling devices. An optical particle counter and a vibrating orifice generator are used in these measurements. This calibration technique is fast and has a high resolution. Investigations were carried out on the influence of various parameters on the classification efficiency of impactors and sampling cyclones. Using the extensive data measured a better understanding and quantification of impactor and cyclone behaviour is developed which may improve their applications in particle sampling.
Application of the Straining Capture Mechanism in gaps to the measurement of particle concentration and size distribution
Authors: Cieślicki Krzystof 
Published: December 2004

AbstractThis paper attempts to answer the question of whether a measurement of the relative flow rate of a suspension of spheres, flowing under constant pressure drop through gaps of precisely determined geometry, may be utilised to measure the concentration and size distribution of the particles. A positive answer is possible only if several restrictions are imposed on the character of the flow, a maximum ratio of sphere diameter to gap height and a maximum number of captured particles. This answer is based on a model of the filtration process taking place in the gap and the consequent relationship between the flow characteristics of the gap and the number and diameter of the captured particles.
Determination of the Adhesivity on Acrylics of Fresh Coal Fly Ash Particles
Authors: Rafailidis Stilianos V. , Reizes John A. 
Published: December 2004

AbstractThe adhesivity of fresh coal fly ashes from two Australian power stations on Dralon‐T monofilaments has been experimentally analysed. It was found that one of the dusts was more adhesive to the fiber and its particles were also more strongly electrostatically charged. These obervations explain the reported large differences in the pressure loss across the fabric filters at the two stations. By precharging the particles, the technique can also be utilized in determining the adhesivity of fly ashes which carry relatively small natural electrostatic charging.
A Laser Multi‐focus System for the Measurement of Particle Size, velocity and refractive index
Authors: Nakatani Noboru , Kohri Shigetoshi , Yamada Tomoharu , Sakabe Toshiya 
Published: December 2004

AbstractA laser multi‐focus velocimeter (LMFV) for measuring particle diameter, velocity and refractive index simultaneously is described. A phase diffraction grating with pulse width modulation is used to obtain several focal points with almost equal intensity and to construct the optical system. The fringes of the LMFV using multi‐beam interference have a sharper intensity distribution and wider period than those of a laser Doppler velocimeter using two‐beam interference. Therefore, the LMFV makes it possible to measure high velocities and large particle diameters with high accuracy. The validity of the method was confirmed theoretically and experimentally.
Light Scattering at a Small Angle with the Use of Lorenz‐Mie Theory in Particle Sizing
Authors: Mroczka Janusz 
Published: December 2004

AbstractProblems connected with particle sizing with the use of radiation power measurement at a small angle (θ = 0.5° – 10°) where the Lorenz‐Mie theory is a mathematical model of the phenomenon are discussed. As an example, a computer program LICZ, allowing for the shortest calculation time, yet preserving satisfactory accuracy of calculations, is considered.
Size Characterization of Liquid‐Borne Particles by light scattering counters
Authors: Lee Haeok Skarda , Chae Seung Ki , Liu Benjamin Y. H. 
Published: December 2004

AbstractThe sizing accuracy of a commercially available laser optical liquid‐borne particle counter is investigated. A calibration study, using aqueous suspensions of non‐absorbing, monodisperse, spherical polymer particles, and a study using suspensions of non‐spherical polydisperse, alumina particles are conducted. The experimental results from the spherical polymer study show an excellent agreement with the theoretical Mie light scattering calculations. The accuracy of the spherical polymer sizing is shown to be within 20% of the actual size. The alumina particle readings are compared to the readings of four different particle sizing instruments and to scanning electron microscope pictures. Although quantitative comparisons are difficult to make between the instruments, the results show a good agreement for the batch of particles with a narrower size distribution.
The Characterization of Water‐Droplet Aerosols by polytec optical particle analysers
Authors: Mitchell Jolyon P. , Nichols Alan L. , van Santen Anton 
Published: December 2004

AbstractA single‐stage impactor has been used to calibrate a Polytec HC‐15/1 optical aerosol analyser so that this instrument can be used to study water droplets from approximately 1 to 20 μm aerodynamic diameter. The resulting calibration data were in good agreement with calculations based on Mie light scattering theory, and gave a conversion factor of 2.0 ± 0.2 between polystyrene latex microspheres and water droplets of the same aerodynamic diameter.Monodisperse water droplets were sampled by a Polytec HC‐70/2 analyser, calibrated using the conversion factor of 2.0. The measured count median diameter agreed closely with that predicted from the well‐defined operating conditions of the vibrating orifice aerosol generator. Size measurements of a polydisperse water‐droplet spray were also undertaken with both a Malvern laser diffractometer and a Polytec HC‐15 analyser; good agreement was achieved between the two techniques.
The Use of Particle Image Velocimetry to Study Roping in Pneumatic Conveyance
Authors: McCluskey D. R. , Easson W. J. , Greated C. A. , Glass D. H. 
Published: December 2004

AbstractParticle Image Velocimetry (PIV) is a new technique which provides an instantaneous velocity profile of a flow field. A PIV system at Edinburgh University has been adapted to study the phenomenon of roping in a pneumatic particle conveyance rig. The principle features of this PIV system are as follows. Double images of the particles transported by the fluid are recorded on photographic film using a conventional camera. The displacement of the particle pairs, which determines the velocity at a particular point, is determined to an automatic analysis system. PIV is proving to be a powerful method in the investigation of roping. A rope is a high density ribbon of particles which is created when a uniform air‐coal flow segregates at a pipe bend into two regimes: one has a low coal to air ratio whereas the second regime, termed the rope, has a high coal to air ratio. This particular problem is connected with the pulverised fuel (pf) pipes of coal‐fired electricity generating stations. The flow, as seen on Figure 1, is reproduced in a 26 mm scale model encompassing the main aerodynamic features of pf pipes. The rope forms in the vertical to horizontal 90° bend, falls from the top to the bottom of the horizontal pipe and creats a deposit.
A Single Expression of Common Particle Size Distribution
Authors: Ogawa Kohei 
Published: December 2004

AbstractA new particle size distribution function based on a simple model is presented. Data generated by the normal, log‐normal and Rosin‐Rammler distribution functions were fitted with this new distribution function and the fitted curves were, for all practical purposes, indistinguishable from all three distributions.The new distribution function can replace all the three functions and thus a means of presenting and comparing the different size distribution patterns in terms of a single mathematical expression is obtained. Additionally, the new distribution function provides the possibility of developing the discussion on the physical meaning of the particle size distribution.
Characterization of Particle Swelling of Materials of Pharmaceutical Interest
Authors: Caramella Carla , Ferrari Franca , Bonferoni M. Cristina 
Published: December 2004

AbstractA method based on the employment of an electrical sensing zone instrument (Coulter Counter) has recently been proposed for the combined measurement of the increase in particle volume (particle swelling) and granulometric characterization of pharmaceutical tablet disintegrants. The performance of the method, as far as its applicability to limited swelling materials is concerned, has been assessed. Both inert materials (polystyrene latices) and limited swelling disintegrants (maize starch and crospovidone in different granulometric fractions) were examined for total particulate volume in aqueous media. The accuracy and repeatability of measurements of both total particulate volume and particle volume increase were defined. The results obtained indicate that the method may be adapted for measuring the increase in particle volume of so‐called limited swelling disintegrants.
Lagrangian Stochastic‐Deterministic (LSD) Predictions of Particle Dispersion in Turbulence
Authors: Milojevié Dragoslav 
Published: December 2004

AbstractA Lagrangian model of particle motion in turbulence has been developed. The model is stochastic in the sense that the "instantaneous" fluid velocity field is generated from known turbulence energy and time scales of large eddies by using a random sampling. The particle motion during the interaction with the eddies is deterministic as being predicted from solutions of Lagrangian momentum equations. On the basis of a large number of calculated trajectories, the distributions of local particle mean and fluctuation velocity components and of the mean square particle displacement are evaluated in a flow domain. The results of the predictions for the case of particle dispersion in nearly homogeneous and isotropic turbulence behind a grid are compared with existing experimental data and satisfactory agreement is achieved. The model is also applied to the case of the particle dispersion from a point source in a nonhomogeneous turbulence of fully developed pipe flow. The agreement with experiments is satisfactory for both heavy and tracer particles. An explanation is given for the experimentally observed phenomenon that in some cases heavy particles disperse faster than fluid points.