bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automatic measurement of the absolute CTE of thin polymer samples. II. Effect of chain orientation on thermal expansion of drawn polymer films
Authors: El‐Tonsy M. M. , Meikhail M. S. , Felfel R. M. 
Published: March 2006

AbstractMore details about the coefficient of thermal expansion (CTE) and thermal expansion anisotropy, Δα, of drawn films from polypropylene (PP) and high density polyethylene (HDPE) are discussed. CTE of the selected polymers are measured along different directions relative to the drawing direction (MD). The coefficient of thermal expansion parallel to drawing direction (α∥) was less than that in the transverse direction for both of the used polycrystalline polymers. Also α∥ for PP and HDPE for different draw ratios are measured. The morphology of measured samples is investigated by using an optical polarizing microscope and from the 2D‐plot of the angular distribution of the absorption coefficient of light through a polymer sample between two crossed polarizers. An agreement between obtained figures was found. Birefringence of samples was measured photometrically. The orientation of drawn polymer chains is estimated from the birefringence measurement. The set up of the used optical system is explained. The CTE variations of drawn polycrystalline polymer are explained on bases of the associated morphological variations. A recommendation was given to produce an all‐PP‐composite with satisfactory dimension stability at elevated temperature. Construction and operation of a simple drawing machine is given too. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4452–4460, 2006
Effect of particle size on flame retardancy of Mg(OH)2‐filled ethylene vinyl acetate copolymer composites
Authors: Huang Honghai , Tian Ming , Liu Li , Liang Wenli , Zhang Liqun 
Published: March 2006

AbstractFour kinds of magnesium hydroxide (Mg(OH)2) with different particle sizes are chosen and mixed with ethylene vinyl acetate copolymer (EVA) to investigate the effect of particle size on the flame retardancy of composites, which is evaluated by limiting oxygen index (LOI) testing, horizontal fire testing, and cone calorimeter. When Mg(OH)2 filling level changes from 35 to 70 wt %, the composites filled with nano‐Mg(OH)2 do not always possess the best flame retardancy, and among the composites filled with micro‐Mg(OH)2, the composites filled with 800 mesh Mg(OH)2 show the best flame retardancy; however, the composites filled with 1250 mesh presents the worst one. So the effect of particle size on the flame retardancy of micro‐Mg(OH)2‐filled EVA is not linear as expected. All the differences are thought to result from both particle size effect and distributive dispersion level of Mg(OH)2. To prepare the composites with better mechanical properties and flame retardancy, authors suggested that Mg(OH)2 of smaller size should be chosen as flame retardant, and good dispersion of Mg(OH)2 particles also should be assured. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4461–4469, 2006
Radiation‐induced crosslinking of acetylene‐impregnated polyesters. II. Effects of preirradiation crystallinity, molecular structure, and postirradiation crosslinking on mechanical properties
Authors: Punyodom W. , Jones R. A. , Ward I. M. , Johnson A. F. 
Published: March 2006

AbstractElectron beam‐irradiated crosslinking has been studied in a series of acetylene‐impregnated polyesters and amorphous copolyesters, including poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(cyclohexane dimethylene terephthalate) (PCDT), and poly(cyclohexane dimethylene terephthalate‐co‐ethylene terephthalate) (P(CDT‐co‐ET)) having 29 and 60 wt % ethylene terephthalate (ET). The extent of crosslinking was observed by gel fraction measurements and was found to be significantly influenced by the aliphatic chain content of the polyesters (PET < PBT < PCDT). In addition, as the preirradiation crystallinity of the polyesters was reduced, the extent of acetylene‐enhanced crosslinking was greatly raised. Decreases in the postirradiation crystalline melting temperature and degree of crystallinity were observed in all the polyesters, using differential scanning calorimetry measurements. Particularly significant findings have been the shift in the glass‐transition temperatures (Tg) to higher temperatures and the decrease in loss tangents at higher temperatures, both of which confirm that crosslinking has taken place. The storage moduli (E′) in the rubbery plateau region of PCDT and P(CDT‐co‐ET) were significantly affected by irradiation dose. Increased network tightness in postirradiated PBT and PCDT films was also inferred from melt‐rheology measurements, in which stress relaxed more slowly following a stepped strain. Improvements in the mechanical properties of the irradiated polyesters and copolyesters were clearly evidenced by the increased modulus at higher temperatures, observed using dynamic mechanical thermal analysis and melt‐rheology methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4476–4490, 2006
Synthesis and characterization of phenolic novolacs modified by chestnut and mimosa tannin extracts
Authors: Peña C. , Larrañaga M. , Gabilondo N. , Tejado A. , Echeverria J. M. , Mondragon I. 
Published: March 2006

AbstractThe possibility of reacting chestnut and mimosa tannins with the intermediates of the synthesis reaction for phenolic novolacs under acid conditions has been proved using differential scanning calorimetry (DSC). The amount of intermediate compounds and the percentage of free phenol and formaldehyde in the reaction mixture is decisive for the determination of the stage in which the addition of tannin is suitable. Synthesis of novolac resins modified with 14 wt % mimosa tannin extract or with several percentages (until 40 wt %) of chestnut tannin have been performed. The reaction pathways have been investigated by DSC, fourier transformed infrared spectroscopy and gel permeation chromatography. Ester groups of chestnut tannin result in a reaction pathway different from the one for mimosa‐modified resins and nonmodified resins. Preliminary studies of curing reactions of synthesized resins with hexamethylenetetramine indicate that the cure of modified‐resins is even more favorable than the one for nonmodified resins. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4412–4419, 2006
Interaction of toughening mechanisms in a hybrid epoxy system
Authors: Kim Nam Ho , Kim Ho Sung 
Published: March 2006

AbstractInteraction between different toughening mechanisms is studied using a heat treated hybrid system, consisting of carboxyl‐terminated butadiene acrylonitrile (CTBN) rubber and EXPANCEL (expandable hollow microspheres) as modifiers for an epoxy resin. It was found that the fracture toughness of the hybrid system is higher than that of either individually EXPANCEL‐ or CTBN‐modified system for a given content of modifier, although the maximum toughness was not substantially high compared with maxima of single modifier systems. Microscopic examination revealed that damage zone due to CTBN particles ahead of the crack reduces due to the presence of EXPANCEL particles and nevertheless its fracture toughness increased. A possibility was deduced that the cavitation due to CTBN assists with promoting compressive stresses around EXPANCEL particles ahead of the crack tip, resulting in increase in fracture toughness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4470–4475, 2006
Rheology and dispersion behavior of high‐impact polystyrene/ethylene–vinyl acetate copolymer/TiO2 nanocomposites
Authors: Wang Zhaobo , Xie Guangwen , Wang Xin , Zhang Zhikun 
Published: March 2006

AbstractTiO2 nanoparticles were introduced into high‐impact polystyrene (HIPS) in the form of a master batch in which TiO2 was predispersed in composites of HIPS and ethylene–vinyl acetate copolymer (EVA) by melt compounding. The resulting materials were analyzed with a Rosand Precision rheometer, transmission electron microscopy, atomic force microscopy, and ultraviolet–visible light spectrophotometry. The results showed that the introduction of TiO2 nanoparticles into HIPS influenced the apparent viscosity of the composites to a rather small extent. The addition of EVA could regulate the rheological behavior of the HIPS/TiO2 master batch greatly. EVA helped the dispersions of the agglomerates of TiO2 nanoparticles in the flow; this was featured by the distinct yielding in the flow after the introduction of EVA, as well as the large change in the non‐Newtonian indices. The dispersions of the HIPS/TiO2 master batch in the HIPS matrix were improved greatly by the addition of EVA. TiO2 nanoparticles were dispersed randomly in HIPS/EVA/TiO2 nanocomposites. The dispersion improvement of the HIPS/EVA/TiO2 master batch was also proved by atomic force microscopy and ultraviolet–visible spectroscopy investigations. The mechanical properties of HIPS/EVA/TiO2 nanocomposites with low TiO2 contents were slightly higher than those of pure HIPS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4434–4438, 2006
Effects of short chain alcohols on the styrene emulsion polymerization
Authors: Chern Chorng‐Shyan , Yu Ting‐Chuan , Hu Ling‐Ling 
Published: March 2006

AbstractThe effects of a series of short chain alcohols, 1‐butanol (C4OH), 1‐pentanol (C5OH), and 1‐hexanol (C6OH), on the styrene (ST) emulsion polymerization mechanisms and kinetics were investigated. The CMC of the ST emulsions stabilized by sodium dodecyl sulfate (SDS) first decreases rapidly and then levels off when the CiOH (i = 4, 5, or 6) concentration ([CiOH]) increases from 0 to 72 mM. Furthermore, at constant [CiOH], the CMC data in decreasing order is CMC (C4OH) > CMC (C5OH) > CMC (C6OH). The effects of CiOH (i = 4, 5, and 6) on the ST emulsion polymerization stabilized by 6 mM SDS are significant. This is attributed to the reduction in CMC by CiOH, the different oil–water interfacial properties, the different concentrations of monomer within latex particles, and the different effectiveness of SDS/CiOH in stabilizing latex particles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4406–4411, 2006
Kinetic and molecular weight control for methyl methacrylate semibatch polymerization. II. Open control
Authors: Wu Jian‐Yi , Shan Guo‐Rong 
Published: March 2006

AbstractThe gel effect will bring a violent increase of conversion for methyl methacrylate (MMA) polymerization in a short time. It will be very dangerous for the reactor, as it causes an increase of molecular weight and broadens the molecular weight distribution. To unify the kinetics, molecular weight, and its distribution, on the basis of the mathematical models for semibatch polymerization of MMA, three controlled objectives that are the heat load distribution index, the change in molecular weight, and molecular weight distribution index are presented. Three materials (monomer, solvent, and chain transfer agent) and their flow rate and feeding mode are analyzed for the open control of kinetics, molecular weight, and its distribution. The optimum flow rate and mode are obtained. The heat load distribution index and molecular weight distribution index are even less than 2.0 and 2.2, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4399–4405, 2006
Graft copolymerization of acrylate monomers onto sulfonated jute–cotton blended fabric
Authors: Mondal Md. Ibrahim H. , Farouqui Faisul Islam , Salam M. Abdus 
Published: March 2006

AbstractGraft copolymerization of acrylate monomers, e.g., methyl methacrylate and ethyl methacrylate, onto bleached sulfonated jute–cotton‐blended fabric was carried out in an aqueous medium, using potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in a nitrogen atmosphere. The parameter variables, e.g., concentrations of monomer, potassium persulfate, ferrous sulfate, reaction time, and reaction temperature, directly influenced the percent graft yield. The percent graft yield increased to a certain value in each variable, and the percent graft yield of methyl methacrylate and ethyl methacrylate was about 15.9 and 17.1%, respectively. Polymer grafting was characterized by thermogravimetric analysis, infrared spectroscopy, and X‐ray diffractometry. Grafting improved the thermal stability, protected from photo‐oxidative degradation, decreased the dyeability, and had positive impact on fastness characteristics. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4393–4398, 2006
Formation of inorganic (TaC, TaN) fibers by thermal decomposition of cellulose acetate–tantalum alkoxide precursor gel fibers
Authors: Nakane Koji , Ogata Nobuo , Kurokawa Youichi 
Published: March 2006

AbstractPrecursor gel fiber was formed by extruding cellulose acetate spinning solution into Tantalum (Ta) pentaethoxide acetone solution in a coagulation bath. Gel formation must be due to the coordination of Ta to OH and CO groups on the pyranose ring. The resultant precursor gel fiber was converted into carbide (TaC) or nitride (TaN) fibers by pyrolyzing them in Ar, N2, or NH3 atmospheres. TaC and TaN fibers can be obtained near theoretical temperatures calculated from thermodynamics data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4320–4324, 2006
New method for the synthesis of clay/epoxy nanocomposites
Authors: Wang H. , Hoa S. V. , Wood‐Adams P. M. 
Published: March 2006

AbstractA new liquid–liquid method for the synthesis of epoxy nanocomposites was developed. This new method improved the dispersion and exfoliation of the organoclay in the polymer matrix, thus improving the end‐use properties. The microstructure and physical properties of the clay/epoxy nanocomposite synthesized by the new method were studied. Rheological tests of the uncured epoxy–organoclay system demonstrated that this method resulted in a great increase in viscosity, much more than the most commonly used direct‐mixing method. The Krieger–Dougherty model successfully described the dispersion of the clay layers in the uncured epoxy. In the 5 wt % organoclay nanocomposite, compressive tests on the cured samples showed that there was a 45% increase in the maximum strength, a 10% increase in the yield strength, and a 26% increase in the modulus over the pure epoxy–amine cured system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4286–4296, 2006
Synthesis, characterization, and kinetic investigation of acrylic monomers derived from acetaminophen and ρ‐cresol as model drug molecules
Authors: Vezvaie Mansoor , Taghizadeh S. Mojtaba , Gholami Mohammed R. 
Published: March 2006

AbstractIn this work, the synthesis, characterization, and kinetic investigation of the free‐radical polymerization of 4‐acetylaminobenzene propenoic ester (ABPE) and 4‐methylbenzene propenoic ester (MBPE) were studied. The kinetic behaviors of ABPE and MBPE in the polymerization initiated by azobisisobutyronitrile in dimethylformamide solutions at temperatures between 50 and 120°C were investigated, and experimental and theoretical conversion–time curves were compared. Both monomers showed a polymerization ceiling temperature (Tc). Tc was calculated with experimental values of kp/k with a constant concentration of 0.7 mol/L for monomers. Tc was about 141 and 131°C for ABPE and MBPE, respectively. In addition, the solvent effect on the polymerization reaction was investigated via the calculation of the solvent chain‐transfer constant (Cs) for the ABPE monomer. Then, Cs was determined from the average degree of polymerization measured with gel permeation chromatography and the calculation of the overall rate of polymerization at 60°C. The results showed that dimethylformamide as a solvent had no effect on the rate of polymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4369–4374, 2006
Dyeing properties of net‐modified cotton fabric with triazine derivative containing the multireactive and multicationic groups
Authors: Xie Kongliang , Sun Yan , Hou Aiqin 
Published: March 2006

AbstractCotton fabric was modified with a 1,3,5‐triazine derivative containing the multireactive and multicationic groups, 2,4,6‐tri[(2‐hydroxy‐3‐trimethyl‐ammonium)propyl]‐1,3,5‐triazine chloride (Tri‐HTAC). Compared with unmodified cellulose, the net‐modified cotton cellulose has different dyeing properties. The modified cotton was dyed with reactive dyes without the addition of salt. The color yield was higher than that on unmodified cotton, despite the addition of large amounts of salt in the latter case. After dyeing, compared with unmodified cellulose with reactive dyes, the reflectance spectrums of modified cotton did not change. The modified cotton got better wash fastness than the unmodified cotton. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4388–4392, 2006
Metabolism of PER.C6TM cells cultivated under fed‐batch conditions at low glucose and glutamine levels
Authors: Maranga Luis , Goochee Charles F. 
Published: March 2006

AbstractThis is the first study to examine PER.C6TM cell glucose/energy and glutamine metabolism with fed‐batch cultures at controlled low glutamine, low glucose, and simultaneous low glucose and low glutamine levels. PER.C6TM cell metabolism was investigated in serum‐free suspension bioreactors at two‐liter scale. Control of glucose and/or glutamine concentrations had a significant effect on cellular metabolism leading to an increased efficiency of nutrient utilization, altered byproduct synthesis, while having no effect on cell growth rate. Cultivating cells at a controlled glutamine concentration of 0.25 mM reduced qGln and q by approximately 30%, qAla 85%, and qNEAA 50%. The fed‐batch control of glutamine also reduced the overall accumulation of ammonium ion by approximately 50% by minimizing the spontaneous chemical degradation of glutamine. No major impact upon glucose/energy metabolism was observed. Cultivating cells at a glucose concentration of 0.5 mM reduced qGlc about 50% and eliminated lactate accumulation. Cells exhibited a fully oxidative metabolism with Y of approximately 6 mol/mol. However, despite no increase in qGln, an increased ammonium ion accumulation and Y were also observed. Effective control of lactate and ammonium ion accumulation by PER.C6TM cells was achieved using fed‐batch with simultaneously controlled glucose and glutamine. A fully oxidative glucose metabolism and a complete elimination of lactate production were obtained. The qGln value was again reduced and, despite an increased q compared with batch culture, ammonium ion levels were typically lower than corresponding ones in batch cultures, and the accumulation of non‐essential amino acids (NEAA) was reduced about 50%. In conclusion, this study shows that PER.C6TM cell metabolism can be confined to a state with improved efficiencies of nutrient utilization by cultivating cells in fed‐batch at millimolar controlled levels of glucose and glutamine. In addition, PER.C6TM cells fall into a minority category of mammalian cell lines for which glutamine plays a minor role in energy metabolism. © 2006 Wiley Periodicals, Inc.
Event‐driven time‐optimal control for a class of discontinuous bioreactors
Authors: Moreno Jaime A. , Betancur Manuel J. , Buitrón Germán , Moreno‐Andrade Iván 
Published: March 2006

AbstractDiscontinuous bioreactors may be further optimized for processing inhibitory substrates using a convenient fed‐batch mode. To do so the filling rate must be controlled in such a way as to push the reaction rate to its maximum value, by increasing the substrate concentration just up to the point where inhibition begins. However, an exact optimal controller requires measuring several variables (e.g., substrate concentrations in the feed and in the tank) and also good model knowledge (e.g., yield and kinetic parameters), requirements rarely satisfied in real applications. An environmentally important case, that exemplifies all these handicaps, is toxicant wastewater treatment. There the lack of online practical pollutant sensors may allow unforeseen high shock loads to be fed to the bioreactor, causing biomass inhibition that slows down the treatment process and, in extreme cases, even renders the biological process useless. In this work an event‐driven time‐optimal control (ED‐TOC) is proposed to circumvent these limitations. We show how to detect a “there is inhibition” event by using some computable function of the available measurements. This event drives the ED‐TOC to stop the filling. Later, by detecting the symmetric event, “there is no inhibition,” the ED‐TOC may restart the filling. A fill‐react cycling then maintains the process safely hovering near its maximum reaction rate, allowing a robust and practically time‐optimal operation of the bioreactor. An experimental study case of a wastewater treatment process application is presented. There the dissolved oxygen concentration was used to detect the events needed to drive the controller. © 2006 Wiley Periodicals, Inc.
Cognitive profiles of adult developmental dyslexics: theoretical implications
Authors: Reid Agnieszka A. , Szczerbinski Marcin , Iskierka‐Kasperek Ewa , Hansen Peter 
Published: March 2006

AbstractThe aim of this study was to establish cognitive profiles of dyslexic adults on tests developed within the three main theories of developmental dyslexia: phonological, visual magnocellular and cerebellar and to investigate which theory can account for these profiles. The sample consisted of 15 Polish university students or alumni with a formal diagnosis of dyslexia, without ADHD and 15 controls matched on education, age, gender, IQ and handedness. The results revealed a striking heterogeneity of profiles. Nine dyslexics exhibited only a phonological deficit; one a phonological and a visual magnocellular deficit; a further three a phonological and a cerebellar deficit; two either a cerebellar or a visual magnocellular deficit. None of the three main theories of dyslexia can account for all the cases studied here. It is suggested that the best account of these data is in terms of different sub‐types of dyslexia with different underlying causes, such as phonological, visual magnocellular and cerebellar, or a combination of these. However, an account in terms of Ramus' (Trends, Neurosci. 2004; 27(12):720–726) model, according to which the phonological deficit is a core deficit in dyslexia and other deficits (magnocellular and cerebellar), are just co‐morbid markers without a causal relationship to dyslexics' literacy difficulties, cannot currently be ruled out. Copyright © 2006 John Wiley & Sons, Ltd.
Calculation of the Ligating Strength of N‐Heterocyclic Germylenes – Extending the π‐Acceptor Range
Authors: Kühl Olaf , Lifson Kirstin , Langel Walter 
Published: March 2006

AbstractThe ligand behaviour of N‐heterocyclic germylenes (NHGe) with respect to their σ‐donor ability, π‐acceptor strength and net electron donating ability is determined by calculating their molecular electrostatic potential (MEP). Correlation of the MEP to the Tolman Electronic Parameter (TEP) is achieved using a family of phosphite ligands. The results indicate that the π‐acceptor strength of NHGe reaches significantly beyond that of phosphites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)