bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure and electrical properties of polypyrrole–thermoplastic elastomer blends
Authors: Radhakrishnan S. , Saini D. R. 
Published: May 2005

AbstractConducting thermoplastic elastomer blends have been synthesised by deposition of polypyrrole in styrene–butadiene–styrene (SBS) block copolymers containing various amounts of ferric chloride (FeCl3). These blends have phasesegregated morphology with preferenatial deposition of polypyrrole in one of the domains as confirmed by structural investigations using optical microscopy, X‐ray diffraction and infrared spectroscopy. The electrical resistivity (ρ) for these blends shows a sharp transition in the region of 273 K and is sensitive to small mechanical deformations both in compressions and extension modes. The dependence of ρ on mechanical stress (P) follows a power law of the type ρ ∝ Pn, where n has a value between 3 and 4. These various findings have been explained on the basis of a phase‐segregated morphology having highly conducting domains separated by a semiconducting/insulating matrix, together with non‐linear conduction processes for charge transport in such heterogeneous materials.
Interpenetrating polymer networks from castor oil‐based polyurethanes and polystyrene, XXV
Authors: Suthar Bhikhu , Jadav Kanak , Dave Mayank 
Published: May 2005

AbstractInterpenetrating polymer networks (IPNs) of castor oil‐based polyurethanes and polystyrene were prepared by simultaneous polymerization. The liquid prepolyurethanes were formed by reacting the hydroxyl functionality of castor oil with isophorone diisocyanate using different stoichiometric NCO/OH ratios. These prepolyurethanes were mixed with styrene monomer and subsequently polymerized by free radical polymerization initiated by benzoyl peroxide in the presence of the crosslinker 1,4‐divinyl benzene. The interpenetrating polymer networks. PU/PS IPNs, were obtained as tough and transparent films by the transfer moulding technique. These IPNs were characterized by the static mechanical properties (tensile strength, Young's modulus and % elongation), thermal properties and morphology. The dielectric relaxation properties (σ, E′, E″ and tanδ) of the IPNs at different temperatures were studied.
Vinyl polymerization initiated by ceric ion–methyl cellosolve redox system in aqueous nitric acid
Authors: Reddy G. Venkataramana , Umamaheswari M. V. , Vidya V. , Krishnaswamy V. 
Published: May 2005

AbstractPolymerizations of methyl methacrylate (MMA) and acrylonitrile (AN) were carried out in aqueous nitric acid at 30°C with the redox initiator system ammonium ceric nitrate–methyl cellosolve (MC). A short induction period was observed, as well as the attainment of a limiting conversion for polymerization reactions. The consumption of ceric ion was first order with respect to Ce(IV) concentration in the concentration range (0.5–3.0) × 10−3 M Ce(IV), and the point at higher concentration deviated from the graph. Plots of the inverse of the pseudo‐first order rate constant for ceric ion consumption, [k′]−1, versus [MC]−1 gave straight lines with non‐zero intercepts for both monomer systems, suggesting complex formation between Ce(IV) and MC. Complex formation between Ce(IV) and reducing agent was also detected by a shift in the absorption maximum of Ce(IV), using a Beckman spectrophotometer. The rates of polymerizations increased with increase in Ce(IV), MC and monomer concentrations; however, at higher concentration of AN (0.2187 M) a steep fall in Rp was observed for AN polymerization. The orders with respect to Ce(IV), MC and monomer for MMA polymerization were found to be 0.22, 0.35 and 1.73 respectively. The orders with respect to Ce(IV), MC and monomer for AN polymerization were found to be 0.56, 0.30 and 1.30 respectively. Maintaining constant nitrate ion in the reaction medium did not significantly change the rate of polymerization with [Ce(IV)], but a fall in RCe was observed. A kinetic scheme involving oxidation of MC by Ce(IV) via complex formation, whose decomposition gives rise to a primary radical, initiation, propagation, and termination of the polymeric radicals by bimolecular interaction, is proposed. An oxidative termination of primary radicals by Ce(IV) is also included.
Studies on the transesterification of polycarbonate/poly(ethylene terephthalate) blends. I: Mechanisms and extent of reaction
Authors: Zheng Wen‐ge , Wan Ze‐hong , Qi Zong‐neng , Wang Fu‐song 
Published: May 2005

AbstractTransesterification of polycarbonate/poly(ethylene‐terephthalate) (PC/PET) blends and the reaction extent were investigated by DSC, FTIR, 1H NMR and Soxhlet extraction. A new characteristic peak appeared in the FTIR spectrum of PC/PET blends after heat treatment, which indicates that new copolymers were formed in the transesterification of the PC/PET blends. The reaction extent was characterized by the absorbance ratios of the FTIR characteristic bands. The reaction extent was associated not only with the reaction conditions but also with the composition of the blends. These results were confirmed by chemical analysis of the extracted products in CH2Cl2 solvent and FTIR analysis. For all the blends studied, the blend with 50/50 wt% had the highest reaction extent. The reaction mechanisms and extent were also confirmed by 1H NMR analysis.
Viscoelastic properties of polystyrene–poly(vinyl methyl ether) blends in oscillatory and steady shear flows near the phase separation temperature
Authors: Takahashi Yoshiaki , Suzuki Hirokazu , Nakagawa Yoshiki , Noda Ichiro 
Published: May 2005

AbstractViscoelastic properties of a polystyrene‐poly(vinyl methyl ether) blend were measured in oscillatory and steady shear flows near the phase separation temperature. In the one‐phase region, the viscoelastic properties are independent of the type of flow and flow geometry, and their shear and frequency dependences are the same as those of homopolymers. When phase separation occurred, a change in viscoelastic properties was observed in all types of flow and flow geometries, and they are different in the different types of flow and/or different flow geometries in the two‐phase region.In the shear rate dependence of viscosity of the polymer blend in the two‐phase region at quiescence, a plateau region was observed, in which the shear viscosity can be regarded as the zero shear viscosity of the homogenized polymer blend at that temperature.
Influence of ZnCl2 on the structure and mechanical properties of polyacrylonitrile fibers
Authors: Cho Seo Hyun , Park Jong Su , Jo Seong Mu , Chung In Jae 
Published: May 2005

AbstractThe structure and mechanical properties of polyacrylonitrile fibers containing small amounts of Zn2+ were investigated. It is possible to interpret the influence of ZnCl2 on the fibers by diffusion. Fibers spun from spinning dope containing ZnCl2 may have a denser and finer structure because ZnCl2 in the spinning dope retards the coagulation rate. The tensile strength and modulus of the fibers are much improved because of the retardation of coagulation. It is probable that the complexation between Zn2+ and CN groups does not contribute to the improvement of the mechanical properties because the amount of ZnCl2 added in a spinning dope is extremely small.
Preparation and morphological characterization of microscopic composite particles
Authors: Shen S. , El‐Aasser M. S. , Dimonie V. L. , Vanderhoff J. W. , Sudol E. D. 
Published: May 2005

AbstractMonodisperse microscopic poly (methyl methacrylate)/polystyrene composite particles of 1–10 μm diameter were prepared by seeded emulsion polymerization of styrene in poly (methyl methacrylate) seed particles which were initially prepared by dispersion polymerization. The resulting composite particles were characterized by transmission and scanning electron microscopy. The unique morphology of the composite particles comprised three types of polystyrene domains embedded in a continuous poly (methyl methacrylate) matrix: the dispersed “internal” domains in the interior, the interconnected “subsurface” domains that from a crust beneath the surface, and the separated “surface” domains at the surface. In addition to thermodynamics and kinetics, the phase separation in composite particles is affected by polymerization mechanism. The complicated particle morphology found is attributed to the coexistence of bulk polymerization and emulsion polymerization (radical absorption and desorption) mechanisms. An explanation of the formation of the observed morphology is proposed. With varying poly (methyl methacrylate)/styrene ratio, the internal viscosity and the competition between the two polymerization mechanisms resulted in a series of interesting morphologies.
Ethynyl‐terminated polyethers from new end‐capping agents. II. End‐chain functionalization through nitro displacement
Authors: Lucotte Georges , Cormier Laurent , Delfort Bruno 
Published: May 2005

AbstractEthynyl‐terminated polysulfones and ethynyl‐terminated polyether‐ketones were prepared in a one‐step polyetherification reaction using new end‐capping agents, respectively 4‐ethynyl‐3′‐nitrodiphenylsulfone and 4‐ethynyl‐4′‐nitrobenzophenone. These reagents were prepared according to a three‐step route each. End‐capping of the polymers involve the nitro displacement by a phenoxide ion. The nitro group was found to be more reactive than the fluoro one as a leaving group. Due to the thermally induced reaction of their ethynyl end‐groups, the polymers lead to materials with improved glass transition temperatures and good thermostability.
Effect of thermal oxidation on the spherulitic morphology of high‐density polyethylene
Authors: Scheirs John , Bigger Stephen W. , Delatycki Oskar 
Published: May 2005

AbstractThe supermolecular structure of high‐density polyethylene (HDPE) at various stages of oxidation was studied using polarized optical microscopy and small‐angle x‐ray scattering (SAXS). Samples of HDPE crystallized isothermally at 123°C show a pronounced change in their spherulitic structure with progressive thermal oxidation. Polarized optical micrographs and SAXS data indicate that the average lamellar thickness decreases concomitantly with thermal treatment. Solid‐state oxidative scission occurs preferentially at the chain folds where the polymer molecules are strained. This process increases the level of crystallinity of the polymer due to the more efficient packing of crystallites formed by the shorter cleaved chains. The morphological changes are related to the polymer melt flow index, molecular weight distribution, crystallinity and peak melting temperature. A model is proposed to account for the changes in the spherulitic morphology.
Relating microhardness of poly(ethylene terephthalate) to microstructure
Authors: Cruz C. Santa , Calleja F. J. Baltá , Zachmann H. G. , Stribeck N. , Asano T. 
Published: May 2005

AbstractThe microhardness (H) of poly(ethylene terephthalate) (PET) containing catalysts, as well as of PET without catalysts has been investigated. Two types of morphologies have been examined: (a) structures where spherulitic growth is incomplete, resulting from a primary crystallization from the glassy state and (b) samples in which spherulitic crystallization is completed. It is shown that for the former materials,His an increasing linear function of the volume of the spherulites and depends on annealing time and catalyst content. For the latter materials,His nearly constant with increasing annealing temperature (TA). Results are discussed in the light of three principal structural factors which determine the microhardness behavior: (1) the volume content of spherulites within the material; (2) the value of crystallinity within the stacks of the lamella, which turns out to be a constant; (3) the average thickness of the crystals, which increases slightly withTAafter crystallization is completed. An expression which takes into account the above parameters and offers a description of theHof polyethylene terephthalate is proposed.
Calculation of the Electrical Field within an Electrical Sensing Zone Counter
Authors: Wilson R. 
Published: May 2005

AbstractIterative numerical analysis methods, similar to those used for ray tracing in electron and ion guns, have been employed to calculate the electrical potential distribution in the vicinity of the orifice of an electrical sensing zone (esz) instrument. In particular, the electrical potential across the mouth of the orifice is considered and the effects of numerically bevelling the sharp peripheral edge are demonstrated.The results support the empirical equation:

for the axial component of the potential gradient, dϕ/dx, at the mouth of the orifice expressed as a function of the radial distance, r, from the centre of the orifice of radius R; α′ and β′ are empirical constants. This equation was derived from previously reported experimental data on relative shifts and heights of artefact peaks apparent on the coarse side of size distributions measured via the esz method on a series of latex copolymers.
Photometric Determination of Respirable Dust Concentration without Elutriation of coarse particles
Authors: Armbruster Lorenz , Breuer Hans , Gebhart Josef , Neulinger Gerold 
Published: May 2005

AbstractThe principle of an instantaneous reading, respirable dust, photometer and its application are described. The instrument measures the infrared light (940 nm wavelength) scattered on airborne particles under a mean scattering angle of 70°. Its open measuring chamber, which is insensitive to daylight, is filled with total dust. The photometer reading, however, is calibrated in terms of mass concentration of respirable dust by means of a gravimetric respirable dust sampler. Experiments carried out with monodisperse test aerosols and with real dusts confirm the instrument's principle. The photometer values obtained for real dusts can be linearly converted into mass values of respirable dust as long as ultra‐fine or ultra‐coarse dusts are excluded. In several practical cases an increased flux of scattered light is compensated for by a higher density of the dust material.
Experimental Investigation of the Tensile Strength of a Powder bed by split cell type tensile testers
Authors: Jimbo Genji , Hatano Shigenobu 
Published: May 2005

AbstractNew types of equipment for measuring the tensile strength of a powder bed, based on the Warren Spring type of split cell, have been developed by the authors and are reported in this paper. The main modification is an extension of the range of the porosity of the powder bed to be tested by improving the sliding mechanism of the split cell. Three versions of the modified equipment are introduced and explained, and the reduction of the sliding friction and the stability of the split cell at a high compression range are shown. The results obtained with beds of a wide porosity range are presented in a new equation for the adhesion force of a powder bed.
Electrochemical Properties of Constituent Minerals of Manganese Nodules
Authors: Nonaka Michio , Uchio Takayasu 
Published: May 2005

AbstractDeep‐sea manganese nodules must be potentially valuable one of the most mineral resources containing several economically valuable metal elements. Manganese minerals in the nodules are regarded principally as todorokite and δ‐MnO2. The todorokite phase is porous and enriched in copper and nickel, while the porous δ‐MnO2 phase is enriched in cobalt. Porosity and adsorption as well as dissolution characteristics have been observed for each constituent mineral. Furthermore the pore diffusion coefficient has been calculated. Moreover, the zeta potential of each constituent mineral has been measured in order to evaluate the electrochemical property. This has been applied successfully to the selective concentration of copper and nickel bearing or cobalt bearing minerals in deep‐sea manganese nodules.
Laser Diffraction Spectrometers/Experience in Particle Size Analysis
Authors: Bürkholz Armin , Polke Reinhard 
Published: May 2005

AbstractOver the past few years, laser diffraction spectrometry has become a very important method of particle size analysis. Typical features include the large measuring range, the simplicity of operation and the speed with which analyses can be carried out. The principle of measurement and the set‐up of three commerical instruments are described.The following points are discussed, with reference to examples:–Relevant parameters, such as particle shape, shape of distribution curve or dispersion, bution curve or dispersion,–reproducibility, comparison of the results obtained with different types of apparatus between one another and with other, analytical methods, and–on‐line use of the instruments for the measurement of dynamic processes, eg. flocculation and dispersion processes.Operating experience gained with six instruments over a number of years is discussed.The measuring method which is described here is in a stage of rapid development and dissemination. It is for this reason that recent improvements and new developments cannot be dealt with here. For example, an apparatus named Helos from Sympatec GmbH, Remlingen, has appeared on the market. The external appearance of the instruments marketed by the Malvern and Leeds and Northrup companies has changed somewhat.The author's practical experience (in some instances extremely wide‐ranging) with these devices is presented here in summary form.
Minimum Sintering Temperatures of Fluidizable Particles
Authors: Compo Peter , Tardos Gabriel I. , Mazzone Dominick , Pfeffer Robert 
Published: May 2005

AbstractExperimental methods to determine minimum sintering temperatures of a variety of granules such as polymers, glass, coal, inorganic salts, etc. are presented. These methods include the use of a dilatometer in which the contraction‐dilation characteristics of a small sample is measured, a differential scanning calorimeter test and an Instron machine by which yield strengths are measured. It is clearly shown that for the majority of materials studied, the different methods give similar values for the minimum sintering temperature but that the dilatometer experiment is the simplest as well as the most reliable method. Since the minimum sintering temperature is always less than the solid's melting point, an efficient method of measuring this temperature is very important for all fluidizable granules subjected to high temperatures. The danger of agglomeration during fluidization increases tremendously at temperatures higher than minimum sintering and therefore special precautions must be taken to avoid defluidization under these conditions.
Quality Control in Solids Process Engineering
Authors: Polke Reinhard , Scholz Norbert 
Published: May 2005

AbstractProduct quality is influenced by the properties of feedstocks and by production parameters. In contrast to gases and liquids, the quality of solids is also affected by the particle properties, such as size, specific surface area, structure and shape. These are the properties which are primarily changed in solids process engineering.The accuracy and cost of possible methods for the measurement of the particle properties of feedstocks, intermediates and end products are discussed. Examples of the methods discussed are laser diffraction spectrometry, quantitative image analysis and photon correlation spectroscopy.The measuring techniques required for monitoring production processes in solids process engineering are illustrated by simple examples. In the field of process control in particular, there is still room for improvement, since there is a lack of suitable sensors and models. Process monitoring is necessary in order to ensure that product quality meets requirements which are constantly increasing.
Approximate Mathematical Description of Particle‐Size Distributions – Possibilities and limitations as to the assessment of comminution and classification processes
Authors: Zisselmar Raimund , Kellerwessel Hans 
Published: May 2005

AbstractDisperse materials are often characterized by their particle‐size distributions which can be determined by different measuring methods. Frequently the quantitative portions of the particle size classes obtained by way of experiment are considered insufficient and one strives for approximating the measured values by an analytic function. This can be reached, more or less satisfactorily, by power, exponential, or normal distribution functions which may include two, three, or four parameters.Publications as well as common practice have proved again and again that due to very rough or incorrect approximations wrong conclusions are derived from test and operating results, so that it appears expedient to investigate – when such an approximation would actually be advisable and – which function would be expedient in the specific case.Application of distriction functions will always be justified then when there is an actual need for utilizing the advantages connected with an approximation. Evaluation of a great number of measuring results revealed that the two‐parameter functions in most cases only permit an utmost rough approximation which might give rise to wrong conclusions. Carefully classified products, however, mostly require three‐ or four‐parameter functions for making an appropriate approximation.The functions, which appear appropriate for certain types of products, are set out in Table 1.In order to make the tabulated individual results accessible to a practical utilization a systematization was attempted. The outcome is a graph which is meant as an assistance for the practician and which presents the possibility of a quick selection of function type.
Dynamic Shape Factors for Particle Shape Characterization
Authors: Dressel Martina 
Published: May 2005

AbstractThe need for particle shape characterization has been internationally recognised and has resulted in a number of publications proposing a variety of methods for particle shape analysis and shape description. Though very important in chemical engineering, correlations between shape parameters and bulk properties are still rare.This paper describes theoretical and experimental investigations of dynamic shape factors for use when calculating the settling velocity of a particle. For this purpose a study of the settling velocities of particles of various shapes has been made. A correlation is developed from the data with which to quantify the effect of shape on settling velocity for particles falling freely in a fluid in the laminar flow range.
Comparison of Light Scattering with other Techniques for Particle Size Measurement
Authors: Tüzün Ug̈ur , Farhadpour Farhad A. 
Published: May 2005

AbstractThe forward‐light scattering technique was compared with three other well known size analysis techniques in determining the size distribution of a crystalline adsorbent, Silicalite (1–10 μm) in a dilute aqueous suspension. The commercial light scattering equipment Malvern was found to produce size distributions within ± 10% agreement with those obtained by scanning electron microscopy (SEM), electronic image analysis (Quantimet) and the electrical sensing zone method (Coulter Counter).This rather surprising accuracy of the light scattering technique with crystal sizes quite close to the wavelength of the incident light is explained by considering the relative refractive index and the light absorbancy of the crystals in the “anamolous diffraction” regime. The theoretical analysis shows quite clearly that the calculation of a “unique” size distribution from a given set of scattering data is possible only when independently measured values of the optical properties are used.The commercial equipment (Malvern) which is currently in use does not require a priori knowledge of the optical properties. The exceptional accuracy obtained with Silicalite crystals using the Fraunhofer approximation in the anamolous diffraction regime is demonstrated with the aid of the light scattering theory to be due to a rather fortunate combination of the light absorptive nature and the polydispersity of the crystals.