bluuebunny/crossref_metadata_2025_split huggingface dataset:
A two‐dimensional model for simulation, control, and optimization of FCC risers
Authors: Souza J. A. , Vargas J. V. C. , Von Meien O. F. , Martignoni W. , Amico S. C. 
Published: February 2006

AbstractA simplified two‐dimensional (2‐D) formulation for FCC risers has been developed. The model approximates the mixture of gasoil, steam, and solid catalyst that flows inside the riser reactor by an equivalent fluid with average properties. The cracking reactions are modeled by a 6‐lump kinetic model combined with two energy equations (gas and solid). Due to the adopted simplifications, a fast and simple‐to‐solve computational code was written; nevertheless, it still is sufficiently precise to be used for the design of new units and for system control and optimization of operating conditions of FCC risers. The validation of the proposed model was performed by direct comparison of the obtained results with available experimental data for a multi‐purpose pilot FCC riser unit. The model was then utilized to simulate an actual size industrial FCC riser. The obtained numerical results in this article demonstrate that the model can be used as a powerful and simple tool for design, control, and optimization of FCC units, combining accuracy with low computational time to obtain solutions when simulating actual FCC riser operation. © 2006 American Institute of Chemical Engineers AIChE J, 2006
A longitudinal functional magnetic resonance imaging study of language development in children 5 to 11 years old
Authors: Szaflarski Jerzy P. , Schmithorst Vincent J. , Altaye Mekibib , Byars Anna W. , Ret Jennifer , Plante Elena , Holland Scott K. 
Published: February 2006

AbstractObjectiveLanguage skills continue to develop rapidly in children during the school‐age years, and the “snapshot” view of the neural substrates of language provided by current neuroimaging studies cannot capture the dynamic changes associated with brain development. The aim of this study was to conduct a 5‐year longitudinal investigation of language development using functional magnetic resonance imaging in healthy children.MethodsThirty subjects enrolled at ages 5, 6, or 7 were examined annually for 5 years using a 3‐Tesla magnetic resonance imaging scanner and a verb generation task. Data analysis was conducted based on a general linear model that was modified to investigate developmental changes whereas minimizing the potential for missing data.ResultsWith increasing age, there is progressive participation in language processing by the inferior/middle frontal, middle temporal, and angular gyri of the left hemisphere and the lingual and inferior temporal gyri of the right hemisphere and regression of participation of the left posterior insula/extrastriate cortex, left superior frontal and right anterior cingulate gyri, and left thalamus.ConclusionThe age‐related changes observed in this study provide evidence of increased neuroplasticity of language in this age group and may have implications for further investigations of normal and aberrant language development. Ann Neurol 2006
Chemistry of copper trimercaptotriazine (TMT) compounds and removal of copper from copper‐ammine species by TMT
Authors: Dongmei Liao , Yunbai Luo , Ping Yu , Zhigang Chen 
Published: February 2006

AbstractThe acid dissociation constants of 2,4,6‐trimercaptotriazine (H3TMT) were determined by acid‐base titration and now can be employed in the preparation of complexes having specific Cu–TMT ratios. IR, EA and TGA characterized the compounds. We analyzed the relevant IR spectra and attribute 2910–2925, 3030–3250 and 3430 cm−1 to triazine ring overtone, NH stretching vibrations and water in the TMT complexes, respectively. The solubility of Cu–TMT complexes was determined with ICP‐AES. The results indicate that Cu3 (TMT)2 · 2H2O (3) is much more insoluble and more stable than Cu (H2TMT)2 (1), Cu (HTMT)·0.5H2O (2) and CuS. The extremely small value of KSP for compound 3 (2.11 × 10−46) indicates that Na3TMT is a very advantageous chelating agent in precipitating complex copper (e.g. copper‐ammine species) from industrial wastewaters. The influences of ammonia concentration, pH and settling time on the effectiveness of copper precipitation were investigated. Also, a ‘real world’ printed circuit board factory effluent initially containing 350.9 ppm of Cu was treated and it was found that more than 99.9% of the copper was removed from the solution as an insoluble compound 3. Copyright © 2006 John Wiley & Sons, Ltd.
Effect of ultrasound on the viscoelasticity and rheology of polystyrene extruded through a slit die
Authors: Chen Yingzi , Li Huilin 
Published: February 2006

AbstractThe rheological and processing behavior (melt fracture performance) of polystyrene extruded through a slit die is studied as a function of the ultrasound vibration intensity. The apparent viscosity reduces 29% and die pressure reduces 22% compared with that without ultrasound vibration. The viscosity of the melt decreases exponentially as ultrasound intensity increases and an Arrhenius equation fits the data well. Ultrasound vibration also leads to a decrease of the die swell ratio and a postponement of melts fracture. Characteristic relaxation times at the onset of melt fracture are calculated according to the hypothesis that the melt fracture behavior of a polymer is affected by a balance between its viscous (viscosity) and elastic properties (recoverable shear). Ultrasound vibration shortens the relaxation time of polystyrene molecular chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2907–2911, 2006
Failure properties of thermoplastic elastomers from polyethylene/nitrile rubber blends: Effect of blend ratio, dynamic vulcanization, and filler incorporation
Authors: George Josephine , Neelakantan N. R. , Varughese K. T. , Thomas Sabu 
Published: February 2006

AbstractThermoplastic elastomers from blends of high‐density polyethylene and acrylonitrile butadiene rubber were prepared by a melt‐blending technique. The blends were dynamically vulcanized using sulfur, peroxide, and mixed curing systems. The peroxide concentration was varied to obtain samples of varying degrees of crosslinking. The peroxide system showed better mechanical properties. The crosslink density determination by the equilibrium swelling method revealed that the enhancement in properties can be correlated to the extent of crosslinking. It is observed that the effect of dynamic vulcanization on the property improvement is much more pronounced in rubber‐rich blends. To study the effect of filler incorporation on mechanical properties, fillers such as carbon black, silica, silane‐treated silica, and cork‐filled samples were prepared. All filled systems, except cork filled, exhibited superior mechanical properties. Scanning electron micrographs of selected fractured surfaces were analyzed to study the failure mechanism of the different compositions. Various theoretical models were applied to correlate the observed mechanical behavior with that of theoretically predicted values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2912–2929, 2006
Polymer/carbon nanotube composite emulsion prepared through ultrasonically assisted in situ emulsion polymerization
Authors: Xia Hesheng , Qiu Guihua , Wang Qi 
Published: February 2006

AbstractIn this study, ultrasonic irradiation and in situ emulsion polymerization were combined to prepare stable poly(methyl methacrylate‐co‐n‐butyl acrylate) (P(MMA‐BA))/carbon nanotubes (CNTs) composite emulsion, which solves the dispersion problem of CNTs in the latex. Two stages were adopted. In Stage I, ultrasonically initiated in situ emulsion polymerization was conducted to disperse CNTs and prepare the seed emulsion containing polymer coated CNTs. In Stage II, conventional in situ emulsion polymerization was conducted to further enhance the monomer conversion and solid content. The dispersion behavior of MWCNTs in aqueous solution under ultrasonic irradiation was investigated by spectrophotometry. The effects of CNTs content on the emulsion stability and mechanical properties of composite film were studied. The results suggest that in the composite emulsion the long CNTs with a diameter of 20–40 nm are separated and dispersed by the formed polymer latex nanoparticles with a size of 20–40 nm. The spherical polymer latex nanoparticles adhere to the wall of CNTs to form a structure like “grapes on the twig.” The smooth, uniform, and flexible polymer/CNTs composite films were prepared from the composite emulsion. The CNTs can be individually dispersed in P(MMA‐BA)/CNTs composite film. Tensile tests suggest that with the increase in the CNTs content, the Young's modulus and the yield strength of the film increase. Only at 1 wt % CNTs, the Young's modulus increases from 124 to 289 MPa, and the yield strength is improved about ∼14%. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3123–3130, 2006
Linear and networked blends and copolymers of polyimide
Authors: Xia Jiqiang , Wang Jinwei , Srinivasan M. P. 
Published: February 2006

AbstractPreparation and characterization of blends and copolymers of a fluorinated polyimide with network constituents is reported. 4,4′‐Hexafluoroisopropylidene diphthalic anhydride and 4,4′‐diaminodiphenyl ether (6FDA–DDE) polyimide were used as the linear hosts and mellitic acid hexamethyl ester ‐ 4,4′‐diaminodiphenyl ether (MAHE–DDE) was employed as the network constituent for the blend and copolymer. Cast films of the polyimides were characterized by FTIR, XPS, DMA, and TGA. The multifunctional nature of MAHE facilitated crosslinking among the constituents. Both blends and copolymers showed significant improvement in the storage modulus and glass transition temperature relative to that observed for the 6FDA homopolymer. The occurrence of a single glass transition temperature for the blends suggests that they were at least partially miscible. Presence of low molecular weight species in the copolyimides, combined with steric hindrance to crosslinking, may have resulted in the existence of an optimum in the amount of the network components for improving the mechanical properties. Inclusion of network components is presented as a facile method for improving the desirable properties of polyimide. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3000–3008, 2006
A modified model and algorithm for flow‐enhanced crystallization—Application to fiber spinning
Authors: Shrikhande Prashant , Kohler William H. , McHugh Anthony J. 
Published: February 2006

AbstractA modified version of the two‐phase flow‐induced crystallization model of Doufas et al. (J Non‐Newtonian Fluid Mech 2000, 92, 27) for melt spinning of polymeric fibers is presented to address three issues: (1) discontinuities generated due to the imposition of continuation conditions at the crystallization onset at Tmo; (2) excessive strength of the flow enhancement component coupling the total extra stress tensor invariant to the crystallization kinetics; and (3) Avrami isotherms used. The modified model provides seamless, two‐phase predictions for all‐state variables in the fiber‐spinning process and significantly reduces discontinuities. Moreover, a new component for the flow‐induced crystallization rate and Avrami crystallization rate isotherms increase the predictive capability of the model. Quantitative prediction of the velocity, stress, temperature, density (or crystallinity), and birefringence profiles are demonstrated for Nylon 66 and PET melts for a variety of process conditions, including predictions of quenched‐sample density profiles and the take‐up speed dependence of as‐spun fiber density. The new algorithm, assisted by the coupling model, provides a more efficient and robust convergence of steady‐state calculations and has been tested to predict spinning phenomena up to spin speeds of 9000 m/min. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3240–3254, 2006
Thermal and wide angle X‐ray analysis of chemically and radiation‐crosslinked low and high density polyethylenes
Authors: Khonakdar H. A. , Jafari S. H. , Taheri M. , Wagenknecht U. , Jehnichen D. , Häussler L. 
Published: February 2006

AbstractLow and high density polyethylenes (PE) were crosslinked by two methods, namely, chemically by use of different amounts of tert‐butyl cumyl peroxide (BCUP) and by irradiation with different doses of electron beam. A comparison between the effects of these two types of crosslinking on crystalline structure, crystallinity, crystallization, and melting behaviors of PE was made by wide angle X‐ray diffraction and DSC techniques. Analysis of the DSC first heating cycle revealed that the chemically induced crosslinking, which took place at melt state, hindered the crystallization process and decreased the degree of crystallinity, as well as the size of crystals. Although the radiation‐induced crosslinking, which took place at solid state, had no significant influence on crystalline region, rather, it only increased the melting temperature to some extent. However, during DSC cooling cycle, the crystallization temperature showed a prominent decrease with increasing irradiation dose. The wide angle X‐ray scattering analysis supported these findings. The crystallinity and crystallite size of chemically crosslinked PE decreased with increasing peroxide content, whereas the irradiation‐crosslinked PE did not show any change in these parameters. As compared with HDPE, LDPE was more prone to crosslinking (more gel content) owing to the presence of tertiary carbon atoms and branching as well as owing to its being more amorphous in nature. HDPE, with its higher crystalline content, showed relatively less tendency toward crosslinking especially by way of irradiation at solid state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3264–3271, 2006
Calorimetric analysis of the multiple melting behavior of poly(L‐lactic acid)
Authors: Di Lorenzo Maria Laura 
Published: February 2006

AbstractThis article contains a detailed calorimetric analysis of the multiple melting behavior of poly(L‐lactic acid) (PLLA) in dependence of crystallization conditions. PLLA crystals formed upon primary crystallization have a greater tendency to reorganize into more stable structures during the heating scan that leads to fusion. Depending on crystallization temperature, one or multiple melting endotherms and/or reorganization exotherms can be evidenced. This complex melting behavior arises from the fusion of a certain amount of the original crystals (already partially perfected during the heating scan), followed by recrystallization and final melting of more perfect crystals, partly grown during primary crystallization, and partly formed through the reorganization processes occurring during the heating scan. A detailed map of the melting behavior of PLLA is described in this contribution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3145–3151, 2006
Determination of the α, β, and γ crystalline phases of poly(vinylidene fluoride) films prepared at different conditions
Authors: Gregorio Rinaldo 
Published: February 2006

AbstractSamples containing the three crystalline phases of poly(vinylidene fluoride), α, β, and γ, have been obtained under distinct crystallization conditions. Samples containing exclusively unoriented β phase have been obtained by crystallization from dimethylformamide (DMF) solution at 60°C. Oriented β phase has been obtained by uniaxial drawing, at 80°C, of an originally α phase sample. Samples containing exclusively α phase have been obtained by melting and posterior cooling at room temperature. Samples containing both α and γ phases have been obtained by melt crystallization at 164 °C for 16 and 36 h. Presence of the crystalline phases in each sample were confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), wide‐angle X‐ray scattering (WAXD), polarized light optical microscopy (PLOM), and scanning electron microscopy (SEM). Infrared absorption bands identifying unequivocally the presence of β and γ phases in a sample are presented. It is shown that solution crystallization at T < 70°C always results in the β phase, regardless of the solvent used. Melt temperatures of the respective phases have also been determined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3272–3279, 2006
Conductive polymer composites: Electrical, thermal, and rheological study of injected isotactic poly(propylene)/long stainless‐steel fibers for electromagnetic interferences shielding
Authors: Feller J. F. , Roth S. , Bourmaud A. 
Published: February 2006

AbstractThe influence of long stainless‐steel fibers (LSSF) on electrical, rheological, and calorimetric properties of conductive composites with poly(propylene) matrix was investigated as a function of filler content from ϕ = 0.15 to 3.6% v/v (1.3 to 23.5% w/w). The results show interesting features of the crystallization process: fibers act as nucleating agents and generate transcrystalline phases in quiescent conditions. LSSF also influences the flow properties and the dynamic rheological behavior, which is evidenced by evolution of G′ and G″ curves with filler content. Finally, SEM pictures of injected samples were used to determine the distribution and orientation of the fibers in the part thickness at different distances from the injection point. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3280–3287, 2006
Effect of fillers on the relaxation behavior of chlorobutyl vulcanizates
Authors: Sridhar V. , Chaudhary R. N. P. , Tripathy D. K. 
Published: February 2006

AbstractThe effect of addition of fillers (carbon black (CB), carbon silica dual phase filler (CSDPF), and nanoclays) on the relaxation behavior of chlorobutyl vulcanizates has been studied. The primary relaxation (α‐transition, the glass transition) was studied by dynamic mechanical analysis as a function of temperature (−60 to +100°C) and positron annihilation life time spectroscopy (−70 to +110°C). Irrespective of the filler and its loading, all the composites showed the glass transition temperature in the range of –29 to –33°C, which was explained on the basis of relaxation chain dynamics of polyisobutylene in the vicinity of fillers. The secondary relaxation (α* or β relaxation) was studied using dielectric relaxation spectra in the frequency range of 100–106 Hz. Nanoclays had a profound influence on the secondary relaxation, whereas CSDPF and CB had a marginal effect. The nonlinear strain dependent dynamical parameters were also evaluated at double strain amplitudes of 0.07–5%. The nonlinearity in tan δ and storage modulus has been explained on the concept of filler–polymer interactions and the interaggregate attraction (filler networking). The “percolation limit” of the fillers in the composites has been studied by DC conductivity measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3161–3173, 2006
Synthesis, characterization, and dilute solution properties of pH‐responsive polyacyloylethylpiperazinium polymers
Authors: Mylswamy S. , Ramamurthi V. , Balasubramanian S. 
Published: February 2006

AbstractFour different pH‐ and electrolyte‐responsive polymers were synthesized from ethyl piperazine with four different counter ions viz., chloride, bromide, sulfate, and nitrate. IR and NMR spectroscopic techniques confirmed the structure of monomers and polymers. Thermal properties of these polymers were investigated by TGA and DSC analysis. The dilute solution properties in pure water, in inorganic simple salt solutions, and pH‐responsive behavior of these polymers were studied by the measurement of viscosity by Ubbelohde viscometer. Flocculation behavior of these polymers was investigated by turbidity studies with bentonite suspension. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3174–3186, 2006
Biodegradation potential of some barrier‐coated boards in different soil environments
Authors: Nazhad M. M. , Sridach W. , Retulainen E. , Kuusipalo J. , Parkpian P. 
Published: February 2006

AbstractThree pilot barrier‐coated boards that were recently produced at the Tampere University of Technology were tested for biodegradation potential using the soil‐burial test method. The tests were conducted in the field as well as in the laboratory. We found that the baseboards degraded regardless of differences in coating; however, the degradation rate was different. The laboratory conditions as well as the addition of inoculum accelerated the degradation process. The coated layer of the boards was isolated by laminating with black polyethylene; then their biodegradation rate was compared to the biodegradation rate of the control, boards coated with low‐density polyethylene. It was observed that paperboards coated with polyester‐based polymers were biodegradable but at different rates. The differences in the biodegradation rates of the boards were attributed to their coating formulations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3193–3202, 2006
Oxidation of hydroquinone to p‐benzoquinone catalyzed by Cu(II) supported on chitosan flakes
Authors: Guibal Eric , Vincent Thierry , Touraud Evelyne , Colombo Simon , Ferguson Andrew 
Published: February 2006

AbstractCopper (sorbed on chitosan flakes) was used as a catalyst for the oxidation of hydroquinone, with dioxygen (from air) and hydrogen peroxide as oxidizing agents. The supported catalyst was very efficient at oxidizing hydroquinone into p‐benzoquinone. With hydrogen peroxide at pH 5.8, drastic oxidizing conditions led to the formation of subproducts. With a short contact time, together with the use of a low hydrogen peroxide concentration and a small amount of the catalyst, the formation of subproducts could be minimized. The influence of the catalyst/substrate and hydrogen peroxide/substrate ratios was investigated to determine optimum experimental conditions for a high initial oxidation rate and a high production of p‐benzoquinone. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3034–3043, 2006
Polyaniline hollow microspheres constructed with their own self‐assembled nanofibers
Authors: Huang Kun , Meng Xiao‐Hong , Wan Meixiang 
Published: February 2006

AbstractPolyaniline (PANI) hollow microspheres constructed with their own nanofibers were prepared by inversed microemulsion polymerization associated with a template‐free method in the presence of β‐naphthalene sulfonic acid (β‐NSA) as the dopant. The hollow microspheres were 4.0–6.0 μm in outer diameter and 150–250 nm in shell thickness; they consisted of the nanofibers (20–30 nm in diameter and 150–250 nm in length). We propose that the coordination effect of the reversed emulsion and the dopant or dopant/aniline micelle might have been a driving force in the formation of the special microstructures/nanostructures, where the reversed microemulsion acted as a soft template in the formation of the microspheres and where NSA or the aniline/NSA micelle was regarded as a soft template in the formation of the nanofibers. The molar ratio of water to the aniline/NSA salt and ultrasonic irradiation were critical in the control of the formation yield and the diameter of the uniform microspheres. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3050–3054, 2006