bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethnic differences in stroke recurrence
Authors: Lisabeth Lynda D. , Smith Melinda A. , Brown Devin L. , Moyé Lemuel A. , Risser Jan M. H. , Morgenstern Lewis B.
Published: August 2006

Objective

To determine whether stroke recurrence and the effect of recurrence on mortality differ by ethnicity.

Methods

Using methods from the Brain Attack Surveillance in Corpus Christi project, we prospectively identified first‐ever ischemic strokes from emergency department logs and hospital admissions (January 2000 to December 2004). Recurrent strokes and deaths were identified for the same period. Cumulative probability of stroke recurrence was estimated. Cox proportional hazards models were used to examine ethnic differences in recurrence and to examine the relation among ethnicity, recurrence, and mortality.

Results

During the time interval, 1,345 first‐ever ischemic strokes were validated. Median age of patients was 72 years; 53% were Mexican American (MA). There were 126 recurrent strokes. Cumulative risk for recurrence at 30 days and 1 year was 2.6 and 7.5%, respectively. MAs had higher risk for stroke recurrence (risk ratio, 1.57; 95% confidence interval, 1.05–2.34) compared with non‐Hispanic white patients, adjusted for demographics, stroke risk factors, and stroke severity. Stroke recurrence was related to mortality to a similar extent across ethnic groups (non‐Hispanic white patients: risk ratio, 3.32; 95% confidence interval, 2.07–5.32; MAs: risk ratio, 2.35; 95% confidence interval, 1.42–3.88).

Interpretation

MAs had higher stroke recurrence risk compared with non‐Hispanic white patients. Stroke recurrence had an important impact on mortality. Efforts to reduce stroke recurrence in MAs are needed. Ann Neurol 2006
Encoded Microcarriers For High‐Throughput Multiplexed Detection
Authors: Wilson Robert , Cossins Andrew R. , Spiller David G.
Published: August 2006

Since the decoding of the human genome, the quest to obtain more and more molecular information from smaller and smaller samples is intensifying. Today the burden of this challenge is being borne by planar arrays, but the quality of the data provided by this approach is limited by variations in performance between different arrays. Suspension arrays of encoded microspheres provide higher quality data, but the amount of molecular information that can be acquired with them is limited by the number of codes that can be distinguished in the same sample. New methods of preparing encoded particles promise to alleviate this problem, but in the face of a growing number of new technologies it is sometimes difficult to decide which, if any, will succeed. Herein we appraise these new forms of encoded particle critically, and ask if they can deliver the necessary multiplexing power and whether they will perform well in multiplexed assays.
Simulate methylation reaction of arsenic(III) with methyl iodide in an aquatic system
Authors: Chen Baowei , Wang Thanh , He Bin , Yuan Chungang , Gao Erle , Jiang Guibin
Published: August 2006

The methylation reaction of inorganic arsenic occurring in aquatic systems was studied by HPLC‐HG‐AFS as a method to separate and detect soluble methylarsenic species. Transformation from inorganic arsenic to methylarsenic was essential for major changes in toxicity to organisms. Monomethylarsenic [AsOCH3(OH)2] was the only product in the methylation reaction of inorganic arsenic(III) with methyl iodide (MeI). This process can be described as an oxidative carbonium‐ion transfer, with MeI acting as a methyl donor. From a thermodynamic point of view, the activity of the carbonium ion and pH were the two major influencing factors. The pH dependence of redox potential of As(III) was the reason for the effect of pH on methylation of arsenic. The influences of salinity and concentration of the methyl donor may be explained by their effects on the activity of carbonium. Moreover, kinetics experiments demonstrated that the methylation reaction was first‐order for both As(III) and methyl iodide. First‐order reaction rates were also calculated at different pH, salinity and MeI, and were found to be in the range 0.0026–0.0123 h−1. The methylation rate varied largely under different reaction conditions. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis and characterization of cassava starch graft poly(acrylic acid) and poly[(acrylic acid)‐co‐acrylamide] and polymer flocculants for wastewater treatment
Authors: Jiraprasertkul W. , Nuisin R. , Jinsart W. , Kiatkamjornwong S.
Published: August 2006

Starch‐g‐poly(acrylic acid) and poly[(acrylic acid)‐co‐acrylamide] synthesized via chemically crosslinking polymerization were then each mixed with inorganic coagulants of aluminum sulfate hydrate [Al2(SO4)3·18H2O], calcium hydroxide [Ca(OH)2], and ferric sulfate [Fe2(SO4)3] in a proper ratio to form complex polymeric flocculants (CPFs). All CPFs exhibited low water absorbency than those of the uncomplexed superabsorbent copolymers. The color reduction by the CPFs was tested with both synthetic wastewater and selected wastewater samples from textile industries. The synthetic wastewater was prepared from a direct dye in a concentration of 50 mg dm−3 at pH 7. The CPFs of poly[(acrylic acid)‐co‐acrylamide] with calcium hydroxide at a ratio of 1:2 is the most effective CPF for the wastewater color reduction. The CPF concentration of 500 mg dm−3 could reduce the color of the synthetic wastewater containing the direct dye solution by 95.4% and that of the industrial wastewater by 76%. Starch‐g‐poly(acrylic acid)/Ca(OH)2 CPF can reduce the synthetic direct dye and the industrial wastewater by 74% and 18%, respectively. Chemical oxygen demand, residual metal ion concentrations, pHs, turbidity of the wastewater were also investigated and the potential use of the complex polymer flocculants for textile wastewater treatment was indicated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2915–2928, 2006
DSC study of transitions involved in thermal treatment of foamable mixtures of PE and EVA copolymer with azodicarbonamide
Authors: Reyes‐Labarta J. A. , Olaya M. M. , Marcilla A.
Published: August 2006

The transitions and reactions involved in the thermal processing of binary mixtures of polyethylene and poly(ethylene‐co‐vinyl acetate) copolymers with different concentrations of a foaming agent (azodicarbonamide) were studied using differential scanning calorimetry (DSC). The effect of ZnO as a kicker also was discussed. The temperature at the maximum rate and the heat evolved were measured for all the processes—melting, transitions, and reactions—all the mixtures prepared were measured and compared. Azodicarbonamide decomposed differently depending on the polymeric matrix. These data can be very useful for the plastic processing industry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2015–2025, 2006
Polymerization of resole resins with several formaldehyde/phenol molar ratios: Amine catalysts against sodium hydroxide catalysts
Authors: Gabilondo N. , Larrañaga M. , Peña C. , Corcuera M. A. , Echeverría J. M. , Mondragon I.
Published: August 2006

Triethylamine and sodium hydroxide catalyzed phenol/formaldehyde resole resins were investigated in terms of their behavior during both addition and polymerization reactions. Amine‐catalyzed prepolymers were mainly ortho‐substituted structures, whereas the sodium hydroxide catalyst directed the addition reaction to para reactive sites. During polymerization, triethylamine led to dimethylene ether bridges as the principal linkages between aromatic structures, increasing their final concentration as the starting hydroxymethyl group concentration increased. In contrast, the use of sodium hydroxide reduced dramatically the dimethylene ether bridge concentration, favoring methylene bridge formation. The influence of hydroxyl ions on the stability of quinone methide intermediates could be the reason for those differences. Despite the formation of dimethylene ether bridges, at higher curing temperatures, more oxidized groups started to appear in cured resoles when the formaldehyde/phenol molar ratio was higher. The presence of infrared bands associated with quinones, aldehydes, and/or carbonyl groups, mainly in high‐formaldehyde‐content resins, could indicate a direct oxidation process from dimethylene ether bridges and/or residual hydroxymethyl groups, without the formation of methylene bridges. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2623–2631, 2006
Nonisothermal crystallization behavior of glass‐bead‐filled polypropylene
Authors: Yuan Qiang , Jiang Wei , An Lijia , Misra R. D. K.
Published: August 2006

The effects of the glass‐bead content and size on the nonisothermal crystallization behavior of polypropylene (PP)/glass‐bead blends were studied with differential scanning calorimetry. The degree of crystallinity decreased with the addition of glass bead, and the crystallization temperature of the blends was marginally higher than that of pure PP at various cooling rates. Furthermore, the half‐time for crystallization decreased with an increase in the glass‐bead content or particle size, implying the nucleating role of the glass beads. The nonisothermal crystallization data were analyzed with the methods of Avrami, Ozawa, and Mo. The validity of various kinetic models for the nonisothermal crystallization process of PP/glass‐bead blends was examined. The approach developed by Mo successfully described the nonisothermal crystallization behavior of PP and PP/glass‐bead blends. Finally, the activation energy for the nonisothermal crystallization of pure PP and PP/glass‐bead blends based on the Kissinger method was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2026–2033, 2006
Synthesis of polystyrene‐b‐poly(ethylene‐co‐butene) block copolymers by anionic living polymerization and subsequent noncatalytic hydrogenation
Authors: Liang Guo‐Dong , Xu Jun‐Ting , Fan Zhi‐Qiang
Published: August 2006

A series of polystyrene‐b‐polybutadiene (PSt‐b‐PBd) block copolymers with various chain lengths and compositions were synthesized by sequential living anionic polymerization and then converted into the corresponding polystyrene‐b‐poly(ethylene‐co‐butene) (PSt‐b‐PEB) block copolymers through the selective hydrogenation of unsaturated polybutadiene segments. Noncatalytic hydrogenation was carried out with diimide as the hydrogen source. The microstructures of PSt‐b‐PBd and PSt‐b‐PEB were investigated with gel permeation chromatography, 1H‐NMR, 13C‐NMR, Fourier transform infrared, and differential scanning calorimetry. The results showed that the hydrogenation reaction was conducted successfully and that the chain length and molecular weight distribution were not altered by hydrogenation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2632–2638, 2006
Synthesis of two‐end‐functionalized copolymer of styrene and methyl methacrylate via living radical polymerization
Authors: Cai Jie , Xu Li , Mao Zhiqing , Chen Zhijun , Liu Yun , Jiang Xiqun , Cheng Rongshi
Published: August 2006

The random copolymers (HO‐P(St‐r‐MMA)‐COOH) of styrene (St) and methyl methacrylate (MMA) with hydroxyl group at one end and carboxyl group at another end were synthesized by nitroxide‐mediated living radical polymerization initiated by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and 4‐hydroxyl‐2,2,6,6–tetramethylpiperidineoxyl (TEMPO‐OH). The experimental results have shown that all synthesized copolymers have narrow molecular weight distribution. The conversion of monomers and the molecular weight of copolymer increase with polymerization time. Thus, a copolymerization mechanism containing living radical polymerization is suggested. The use of this method permits the copolymer with two functional chain ends and controllable molecular weight as well as low molecular weight distribution. X‐ray photoelectron spectroscopy result shows that the synthesized copolymers can be tethered on the surface of silicon wafer through the reaction between the hydroxyl end of the copolymer and native oxide layer on the wafer. In addition, an organic/inorganic hybrid surface has achieved by treating copolymer tethered Si‐substrates with SiCl4 vapor. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3118–3122, 2006
Transport properties of trogamid: Comparison of different experimental techniques*
Authors: Etxeberria A. , Garcia A. , Iriarte M. , Iruin J. J. , Uriarte C.
Published: August 2006

The transport properties of an amorphous polyamide, poly(trymethylhexamethylene terephtalamide) or Trogamid‐T, were determined by different experimental methods. Sorption methods included two electrobalances, one for subatmospheric pressures and the other one up to 20 bar, and a pressure decay cell. Also, a permeability cell was used to measure permeability coefficients for pure gases and a gas mixture. The solubility, diffusion, and permeability coefficients calculated by different methods were in good agreement. With regard to permeability, measurements showed the difference between ideal and real permselectivity. Moreover, the results confirmed the good barrier properties of Trogamid‐T. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2034–2042, 2006
Ultrasonic treatment of polypropylene, polyamide 6, and their blends
Authors: Lin Heng , Isayev A. I.
Published: August 2006

The mechanical and rheological properties of polypropylene (PP), polyamide 6 (PA6), and their blends treated by high‐intensity ultrasound during extrusion were investigated. A lower head pressure was achieved in the extrusion of these thermoplastics. The mechanochemical and sonochemical effects of ultrasound led to simultaneous ionic condensation reactions and degradation in a homogeneous melt of PA6, with a prevailing effect of enhanced polycondensation reactions. The observed improvements in the mechanical properties of ultrasonically treated PA6 were attributed to condensation reactions, which yield a higher molecular weight, a higher crystallinity, and a more uniform crystal size distribution. At high ultrasound amplitudes, for PP, the degradation of polymer chains was observed with little deterioration of the mechanical properties. For ultrasonically treated PP/PA6 blends, a competition between the degradation and partial in situ compatibilization effect was found. At certain blend ratios, the tensile toughness and impact strength of the treated blends were almost double those of the untreated blends. However, full compatibilization was not achieved, possibly because of the low coupling selectivity of highly reactive radicals. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2643–2653, 2006
Nonequilibrium morphology development in seeded emulsion polymerization. V. The effect of crosslinking agent
Authors: Stubbs Jeffrey M. , Sundberg Donald C.
Published: August 2006

It is understood that a major controlling factor in the development of latex particle morphology is the extent to which second stage oligomeric radicals can diffuse into the particles after entry from the aqueous phase. This leads to the expectation that any factor which decreases the diffusion rate of second stage radicals should decrease radical penetration, and thus favor the formation of core–shell type morphologies. The occurrence of crosslinking reactions during the second stage may be one such factor, since the branched and crosslinked chains diffuse much more slowly (if at all) than their linear counterparts. This paper addresses the effect of the addition of crosslinking agent (a divinyl monomer) during the second stage polymerization on particle morphology. It is shown experimentally that, contrary to what one might expect, crosslinking during the second stage has very little, if any, effect on morphology. Modeling suggests that the reason is that the probability for radicals to develop a branch before penetrating a significant distance into the particles is very low (under conditions where full penetration is possible in the absence of crosslinking agent), especially for what is considered to be typical concentrations of crosslinking agent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2043–2054, 2006
Poly(methyl methacrylate) as masking material for microelectromechanical system (MEMS) fabrication
Authors: Bodas Dhananjay S. , Gangal S. A.
Published: August 2006

In the present study direct current (dc) sputtered poly(methyl methacrylate) (PMMA) films deposited on silicon substrates were evaluated as masking materials for anisotropic etching of silicon in aqueous potassium hydroxide (KOH) and tetramethyl ammonium hydroxide (TMAH) solutions. Sputtered PMMA films were characterized by FTIR to ascertain the bonding, by X‐ray photoelectron spectroscopy (XPS) for the elemental composition, and by the contact angle for measuring the adhesion of the film with the substrate. FTIR and XPS data showed the presence of a poly(tetrafluoroethylene)‐like film on the silicon substrate. The interfacial tension was calculated from the contact angle value, which was 0.82 dyne/cm, confirming good adhesion of the film and the substrate. A pattern was lithographically transferred through the masking material on the silicon substrate, and the etch rate of the masking layer was calculated from the masking time data of the films. The etch rate value of 4 Å/min obtained for the masking material is low compared to the etch rate of the conventional masking materials (60 Å/min for SiO2 and 8 Å/min for Si3N4). © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 2094–2098, 2006
Water vapor adsorption and volumetric swelling of melt‐impregnated wood–polymer composites
Authors: Zhang Yaolin , Zhang S. Y. , Chui Ying Hei
Published: August 2006

Wood–plastic composites were prepared through impregnation of solid wood with polyethylene. A resolution IV screening design of 16 runs for seven factors at two levels was adopted. The seven factors tested were ratio of maleated polyethylene in formulations, ratio of polyethylene of different molecular weights, four process factors (vacuum, pressure, time, and temperature), and wood species (red maple and aspen). Moisture adsorption content and volumetric changes as a function of time were investigated. This study also examined the effects of impregnation parameters and impregnants on water vapor adsorption and dimensional stability. The process parameters (pressure and temperature), polymer impregnants (polyethylene of different molecular weights), and wood species contributed significantly to the equilibrium moisture content (EMC), whereas the moisture adsorption rate was mainly affected by the polymer impregnants (polyethylene of different molecular weights). The EMC was inversely proportional to polymer retention. However, none of the variables significantly contributed to volumetric swelling; the volumetric swelling rate was mainly affected by wood species, the molecular weight of the polyethylene, and impregnation vacuum. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2668–2676, 2006
Preparation and properties of a new coating method for preparing conductive polyester fibers with permanent conductivity
Authors: Jin Xin , Xiao Changfa , An Shulin , Wang Yongyue , Jia Guangxia
Published: August 2006

A new coating method based on dissolution (the dissolving‐coating method) was designed to prepare carbon black–coated electrically conductive polyester fibers. The effects of the composition of the coating mixture on the volume resistivity of the fibers were investigated. The mechanical properties and conductive permanence of the coated fibers were studied. The coated fibers prepared by the dissolving‐coating method had the characteristics of lower volume resistivity (9.6 × 100 Ω cm) and permanent conductivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2685–2691, 2006
Thermal and mechanical properties of poly(ethylene terephthalate)/lamellar zirconium phosphate nanocomposites
Authors: Brandão Lilian S. , Mendes Luís C. , Medeiros Marta E. , Sirelli Lys , Dias Marcos L.
Published: August 2006

The preparation of nanocomposites of poly (ethylene terephthalate) (PET) and lamellar zirconium phosphorous compounds by melt extrusion was investigated. Two types of zirconium phosphorous compounds were synthesized by the direct precipitation reaction method: α‐zirconium bis(monohydrogen orthophosphate) monohydrate (ZrP) and organic–inorganic hybrid layered zirconium phenylphosphonate (ZrPP). Composites containing 2 and 5 wt % ZrP and ZrPP were prepared in a twin‐screw extruder and specimens were obtained by injection molding. The extent of dispersion of the layered filler in the composite matrix was investigated by X‐ray diffraction and transmission electron microscopy (TEM). The crystallization and thermal properties were analyzed by differential scanning calorimetry and thermogravimetry, and the mechanical properties were evaluated by tensile tests. Whereas ZrP‐containing composites showe characteristic diffraction peaks at 2θ 11.7° (d = 7.54 Å), indicative of no delamination, ZrPP showed practically no low‐angle diffraction peak at 2θ 5.5° (d = 15.24 Å), indicating loss of the layered order. TEM images of ZrPP particles indicated the formation of an intercalated/partially delaminated nanocomposite. The behavior was attributed to the higher affinity of the polyester with phenyl groups on the platelet surface of ZrPP. In both cases, the addition of the fillers increased the crystallization rate and the modulus. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3868–3876, 2006
Removal of endocrine disruptors in milk by circulation through polydimethylsiloxane tubing
Authors: Higuchi Akon , Takayama Emi , Hirai Kazunari , Ishikawa Takako , Takizawa Nobuko , Sakurai Masaru , Egashira Satsuki , Matsuoka Yuki , Natori Shizue Hayashi
Published: August 2006

A simple circulating system was developed, in which an aqueous solution, cow milk, or human milk was circulated through hydrophobic polymeric tubing to remove the endocrine disruptors from the solution by sorption into the tubing. The effect of circulating parameters, such as tube length, circulating time, and flow rate, against the removal ratio (R) of endocrine disruptors was investigated. R of 1,2,3,4,5,6‐hexachlorocyclohexane (γ‐HCH, lindane) increased with the length of the hydrophobic polymeric tubing, circulating time, and flow rate when cow milk containing 1 ppm γ‐HCH was circulated through polydimethylsiloxane tubing. The R values of several endocrine disruptors with different octanol–water distribution coefficients (log Pow) was investigated for γ‐HCH and dichlorodiphenyltrichloroethane in an aqueous solution, cow milk, and human milk. A similar trend for R versus log Pow of the human milk to that of the aqueous solution and cow milk was observed. The R values of the endocrine disruptors decreased in the following order: Aqueous solution > Human milk > Cow milk. Stable micelles in cow milk disturbed the shift of the endocrine disruptors from the milk micelles into the hydrophobic tubing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3634–3640, 2006
Synthesis and properties of fluorinated aromatic poly(amide imide)s based on 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone and various bis(trimellitimide)s
Authors: Su Yu‐Yang , Yang Chin‐Ping
Published: August 2006

A CF3‐containing diamine, 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone (2), was synthesized from 4,4′‐dihydroxybenzophenone and 2‐chloro‐5‐nitrobenzotrifluoride. Imide‐containing diacids (3 and 5Ba–5Bg) were prepared by the condensation reaction of aromatic diamines and trimellitic anhydride. Then, two series of novel soluble aromatic poly(amide imide)s (PAIs; 6Aa–6Ak and 6Ba–6Bg) were synthesized from a diamine (4Aa–4Ak or 2) with the imide‐containing diacids (3 and 5Ba–5Bg) via direct polycondensation with triphenyl phosphate and pyridine. The aromatic PAIs had inherent viscosities of 0.74–1.76 dL/g. All of the synthesized polymers showed excellent solubility in amide‐type solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide (DMAc), and afforded transparent and tough films by DMAc solvent casting. These polymer films had tensile strengths of 90–113 MPa, elongations at break of 8–15%, and initial moduli of 2.0–2.9 GPa. The glass‐transition temperatures of the aromatic PAIs were in the range 242–279°C. They had 10% weight losses at temperatures above 500°C and showed excellent thermal stabilities. The 6B series exhibited less coloring and showed lower yellowness index values than the corresponding 6A series. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3641–3653, 2006
Experimental and theoretical approaches to investigating the miscibility of anhydride‐containing copolymers and dextran
Authors: Can Hatice Kaplan , Barsbay Murat , Güner Ali , Rzaev Zakir M. O.
Published: August 2006

The miscibility behavior of dextran (Dx) with synthesized functional binary poly(citraconic anhydride‐acrylamide) (poly(CA‐alt‐AAm) and ternary poly(citraconic anhydride‐acrylamide‐vinyl acetate) (poly(CA‐co‐AAm‐co‐VA) copolymers was investigated in dilute aqueous solutions by viscometry and in a solid state by Fourier transform infrared (FTIR) spectroscopy. The relative viscosities of each polymer and their blends with Dx/related copolymer ratios of 20 : 80, 50 : 50, and 80 : 20 were measured at body temperature, 37°C, in bidistilled and deionized water. Starting with the classical Huggins equation, results of the viscosity measurements of each parent polymer and their blends were interpreted in terms of miscibility parameters: Δk, Δb, α, β, ΔB, and μ. Based on the sign convention used with these criteria, the miscibility between Dx and related copolymers was found to increase with the weight fraction of Dx in the blends and with the number of AAm units in the copolymer composition. From FTIR spectral analysis, supporting results were achieved that explained the interactions between Dx and the copolymers. Miscibility behavior was also investigated theoretically with Askadskii's miscibility criterion, and the theoretical calculations provided strong evidence supporting the experimental results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2132–2141, 2006
Surface functionalization of polyolefin films via the ultraviolet‐induced photografting of acrylic acid: Topographical characterization and ability for binding antifungal agents
Authors: Costamagna Vanina , Wunderlin Daniel , Larrañaga Maider , Mondragon Iñaki , Strumia Miriam
Published: August 2006

The photoinduced graft copolymerization of acrylic acid with ultraviolet radiation onto films of poly(vinyl chloride), polypropylene, and polyethylene was studied. Benzophenone was used as the initiator for most of the experiments performed. The percentage of grafting was determined by gravimetric measurements, and the characterization of the grafted films was carried out by chemical analysis (Fourier transform infrared spectroscopy, volumetric titration, and dye adsorption). In all samples, the grafted yield increased with the ultraviolet exposure time. High levels of grafting were obtained at room temperature. In addition, optical and atomic force microscopy allowed the topography of the modified films to be studied as a function of the reaction time. The pendant functional groups that were grafted were then used to bind antifungal agents, such as natamycin and crystal violet, and the antifungal properties of the films were demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2254–2263, 2006
Synthesis of a thioether modified hyperbranched polyglycerol and its template effect on fabrication of CdS and CdSe nanoparticles
Authors: Wan Decheng , Fu Qiang , Huang Junlian
Published: August 2006

A thioether‐containing hyperbranched polyglycerol (PG) was synthesized by a simple and effective two‐step reaction; first a part of the hydroxyls of PG was transformed to carbamates by the reaction with the highly reactive 2‐chloroethyl isocyanate, and then the chlorine group was S‐alkylated with HS(CH2)nOH (n = 2, 6, 11). The resulting PGs with various molecular weights were successfully used as template for synthesis of nanoscale cadmium chalcogenide quantum dots (QDs). It was found that the size of these QDs was dependent on the polymer template. Moreover, after solvent evaporation, the polymer was assembled into large cluster, and a variety of morphologies were formed by the cluster inside the QDs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3679–3684, 2006
Development of dispersion in rubber‐particle compounds in internal and continuous mixers
Authors: White James L. , Liu Dan , Bumm Sug Hun
Published: August 2006

Experiments of mixing silica, carbon black, and CaCO3 into various elastomers (EPDM, NBR, and SBR) were carried out in this paper. We have investigated the breakup of filler agglomerates in the mixing process and compared the mixing results between the internal mixer and the NEX‐T continuous mixer. We have evaluated the impact of the elastomer type, filler type, filler loading, and mixing time on the breakup of filler agglomerates. When the filler agglomerates break up, the agglomerate size was reduced to a steady state size. The steady state size primarily depends on the type and primary particle size of the filler. A model was developed for the rate of agglomerate breakup. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3940–3943, 2006
Modification of polyacrylonitrile precursors for carbon fiber via copolymerization of acrylonitrile with ammonium itaconate
Authors: Liu Jian‐Junn , Ge Heyi , Wang Cheng‐Guo
Published: August 2006

Ammonium‐modified polyacrylonitrile was prepared by free‐radical solution copolymerization of acrylonitrile (AN) with ammonium itaconate (AIA), and then it was spun into precursor fibers in this study. Effects of AIA and itaconic acid on the characteristics of the copolymers and precursor fibers were studied in contrast. It has been found that the ammonium modification could obviously increase the hydrophilicity of the copolymer. And in the spinning processes, modified copolymer can withstand higher total draw‐ratio of 12.6 folds, while unmodified copolymer only 8.5 folds. The void volume, fineness, tenacity, and elongation at‐break of the ammonium‐modified precursors are all improved and enhanced. WAXD test manifested that the modified precursors had higher degree of orientation. DSC test showed that the thermal properties of the modified and unmodified precursor fibers were almost the same. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 102: 2175–2179, 2006
Modified sulfonated poly(phthalazinone ether ketone) membranes with inorganic particles for potential applications in PEMFCs
Authors: Hongwei Zhang , Baoku Zhu , Youyi Xu
Published: August 2006

Composite membranes of sulfonated poly (phthalazinone ether ketone)s (SPPEK)s and Zirconium hy drogen phosphate (ZrP) or 12‐phosphotungstic acid (PWA) were prepared by direct blending method. The physicochemical properties of these composite membranes were studied through Fourier transform infrared attenuated total reflection (FTIR‐ATR) spectroscopy, field‐emission scan ning electron microscope (FSEM), X‐ray diffraction (XRD) and thermogravimetry analysis (TGA). The SPPEK/PWA composite membranes showed better properties, whose highest proton conductivity could reach 0.17 S/cm at 80°C under 100% relative humidity (R.H.). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3972–3977, 2006
Synthesis of poly(epichlorohydrin‐g‐methyl methacrylate) graft copolymers by the combination of cationic and atom transfer radical polymerization
Authors: Cakmak Ismail , Baykara Haci
Published: August 2006

Poly(epichlorohydrin) possessing chloromethyl side groups in the main chain was used in the atom transfer radical polymerization of methyl methacrylate and styrene to yield poly(epichlorohydrin‐g‐methyl methacrylate) and poly(epichlorohydrin‐g‐styrene graft copolymers. The polymers were characterized by 1H NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and fractional precipitation method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2725–2729, 2006
Preparation and evaluation of floating‐bioadhesive microparticles containing clarithromycin for the eradication of Helicobacter pylori
Authors: Zheng Jianhua , Liu Chaowu , Bao Decai , Zhao Yanjun , Ma Xiaojun
Published: August 2006

The development of a gastric floating‐bioadhesive drug delivery system to increase the efficacy of clarithromycin against Helicobacter pylori is described. Floating‐bioadhesive microparticles containing clarithromycin were prepared by a combined method of emulsification/evaporation and internal/ion gelation for the treatment of H. pylori infection. Ethylcellulose microspheres (EMs) were prepared by the dispersion of clarithromycin, ethylcellulose, and chitosan in dichloromethane and subsequent solvent evaporation. EMs were coated with alginate by the internal gelation process to obtain alginate–ethylcellulose microparticles (AEMs); then, AEMs were dispersed in a chitosan solution, and chitosan–alginate–ethylcellulose microparticles (CAEMs) were obtained by ion gelation to enhance the bioadhesive properties. The morphologies of EMs and CAEMs were investigated under optical and scanning electron microscopes. In vitro buoyancy and drug‐release testing confirmed the good floating and sustained‐release properties of CAEMs. About 74% of the CAEMs floated in an acetate buffer solution for 8 h, and 90% of the clarithromycin contained in the CAEMs was released within 8 h in a sustained manner. In vivo mucoadhesive testing showed that 61% of the CAEMs could be retained in the stomach for 4 h. Under a pretreatment with omeprazole, the clarithromycin concentration in gastric mucosa of the CAEM group was higher than that of the clarithromycin solution group. These results suggest that CAEMs might be a promising drug delivery system for the treatment of H. pylori infection. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2226–2232, 2006
Monomer apparent reactivity ratios for acrylonitrile/methyl vinyl ketone copolymerization system
Authors: Hou Chen , Liu Junshen , Ji Chunnuan , Ying Liang , Sun Hongbin , Wang Chengguo
Published: August 2006

Methyl vinyl ketone was firstly used to successfully copolymerize with acrylonitrile. This was achieved by using azobisisobutyronitrile as the initiator, and dimethyl sulfoxide as the solvent. Effect of copolymerization systems on monomer apparent reactivity ratios for copolymer of acrylonitrile with methyl vinyl ketone was studied for contrast. Values of monomer apparent reactivity ratios were calculated by Kelen–Tudos method. It has been found that the apparent reactivity ratios in aqueous suspension polymerization system were similar to those in solution polymerization system at polymerization conversion less than 20%. Beyond 50% of conversion, the changes of monomer apparent reactivity ratios become less prominent. In water‐rich reaction medium [(H2O/dimethylsulfoxide (DMSO)>80/20), monomer apparent reactivity ratios were approximately equivalent to those in aqueous suspension polymerization system. In DMSO‐rich reaction medium (DMSO/H2O > 80/20), apparent reactivity ratios were similar to those in solution polymerization system. Values of apparent reaction ratios both decreased when AN/MVK copolymer was synthesized in DMF and DMAc. The values of apparent reaction ratios gradually tend to 1 with increasing the copolymerization temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4045–4048, 2006
Rheological behavior and microstructure of bimodal suspensions of core‐shell structured swollen particles
Authors: Nakamura Hiroshi , Tachi Kazuyuki
Published: August 2006

The rheological behavior and microstructure of bimodal suspensions of core‐shell structured swollen particles have been examined with changing volume ratio of two different sized particles. As the volume fraction of large particles increases, the viscosity, degree of shear‐thinning, and the critical shear stress σc decreases, while the interparticle distance ξ of the microstructure increases. The suspensions exhibit single mode rheological behavior and have a single diffraction peak in the SAXS profiles. These results suggest that the bimodal suspensions of the core‐shell structured swollen particles behave likely to unimodal suspensions of hard spheres with alloy like single mode microstructure composed of hypothetical intermediate size particle. The relationship between σc and ξ can be represented as σc = 3kT/4πξ3, which corresponds to the dynamics of the Brownian hard sphere model with ξ being the particle diameter. These findings indicate that the shear‐thinning of the suspensions can be attributed to dynamical competition between the thermal motion and the hydrodynamic motion under shear flow and that the mechanism can be applied to bimodal suspensions of the swollen particles as well as unimodal suspensions of hard spheres. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 102: 2212–2217, 2006
Effects of hygrothermal ageing on mechanical properties of flax pulps and their polypropylene matrix composites
Authors: Retegi A. , Arbelaiz A. , Alvarez P. , Llano‐Ponte R. , Labidi J. , Mondragon I.
Published: August 2006

The aim of this work was to study the kinetics of water uptake and its influence on mechanical behavior of both flax pulps and their composites with a maleic anhydride polypropylene copolymer (MAPP) modified polypropylene (PP) matrix by immersion in distilled water at 30, 50, 70, and 100°C. Both the influence of two different MAPP compatibilizers and the optimum doses of each ones were analyzed. The kinetics of water uptake was studied from weight measurements at regular interval times. The diffusion coefficient was dependent on the immersion temperature and MAPP content. Tensile modulus and strength of single flax fiber decreased by water immersion. Both flexural strength and modulus of composites decreased as a result of the combined effect of thermal ageing and moisture absorption. MAPP coupling agent increases moisture resistance and mechanical properties for MAPP‐modified systems with respect to the unmodified ones. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3438–3445, 2006
Effect of ionic strength on the temperature‐dependent behavior of hydroxypropyl methylcellulose solution and matrix tablet
Authors: Xu Xiao Ming , Song Yun Mei , Ping Qi Neng , Wang Yan , Liu Xian Yang
Published: August 2006

The focus of the present study is on the temperature‐dependent behavior of hydroxypropyl methylcellulose (HPMC) solutions at various ionic strength levels. Such behavior is then introduced into the study of tablet dissolution with the aim of explaining why ionic strength could vary the dissolution rate or cause the tablets to disintegrate. The results show that increasing the concentration of solute in the dissolution media will affect the thermal property of hydrated HPMC and then have an effect on the matrix tablets dissolution process. Of the thermal property, reduction of the cloud point is believed to have some relationship with the decrease of the dissolution rate, and decline of the thermal gelation temperature (TGT) might be responsible for the disintegration of the matrix tablets. A “gel out” process concerning the mechanism of the disintegration has been put forward, and a rheological method to test the lower critical solution temperature (LCST) is also presented. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4066–4074, 2006
Properties of calcium carbonate filled and unfilled polystyrene foams prepared using supercritical carbon dioxide
Authors: Chiu Fang‐Chyou , Lai Sun‐Mou , Wong Chang‐Ming , Hui Chang Chaio
Published: August 2006

Foaming behaviors of four polystyrenes (PSs) filled and unfilled with various amounts of CaCO3using supercritical carbon dioxide were investigated. The PSs include three general purpose grades with different molecular weights (different melt index) and one high impact grade. By adjusting foaming conditions, foam density was determined for each investigated sample. In general, the sample with a lower molecular weight (i.e. higher melt index) yielded a lower foam density for the three general purpose PSs. With the addition of CaCO3filler, foam density would increase. The inclusion of rubber in high impact PS was found to complicate its foaming behavior. A qualitative correlation between various types of filled/unfilled PSs and foam density was found in a certain range. An optimum foaming temperature range was required to obtain low foam density for each sample. The corresponding change in matrix modulus by employing various PSs and various filler contents apparently affected the resulting foam density. Although several factors were involved in foaming conditions, the addition of CaCO3filler played a significant role in reducing cell size and increasing cell density of the PSs foams investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2276–2284, 2006
Preparation of phenol–urea–formaldehyde copolymer adhesives under heterogeneous catalysis
Authors: Schmidt Kerstin , Grunwald Dirk , Pasch Harald
Published: August 2006

A new synthetic strategy for PUF copolymers based on three steps was developed. In the first step, two precondensates of phenol with formaldehyde and urea with formaldehyde, respectively, were produced. In the second step, the two precondensates were mixed and condensed using a heterogeneous catalyst in a tube reactor at 90°C. The last step is a vacuum distillation to reach the final copolymer compositions. With regard to the properties, the products can be used as adhesive. The copolymers were analysed by gel permeation chromatography (GPC), 13C‐NMR‐spectroscopy, and MALDI‐TOF mass spectrometry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2946–2952, 2006
Phase morphology control of immiscible polymer blends under vibration force field
Authors: Du Yao‐Xue , Qu Jin‐Ping
Published: August 2006

The formulas of polymer melt velocity, shearing rate, and shearing stress under vibration force field are established through simplifying coaxial cylinder circular flow into plane motional flow. On the basis of the concept of energy ratio model, the rate of energy dissipation and the energy ratio about blending systems are expressed, and the affected factors on phase morphology are studied theoretically. The calculated and analytical results of dynamic flow field and energy ratio show that with the increasing of vibration strength, the fluctuating shearing force field exerted on polymer melt and the negative pressure diffusion behavior of instantaneous impulse strengthen. The energy consumption for phase inversion of immiscible polymer blends under vibration force field is less than that of steady state. The parameter controllability of vibration force field provides a more effective method for realizing phase inversion of immiscible polymer blends. The analysis of transmission electron microcopy micrographs of ethylene–propylene–diene terpolymer/polypropylene blends verifies that the energy ratio model and its phase morphology controlling theory have a good coincidence in comparison with experimental results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2299–2307, 2006
Spinning the supercooled PET to obtain highly oriented and crystallized PET fibers at low speeds
Authors: Cao Jinan
Published: August 2006

An attempt has been made to investigate the feasibility for a novel concept of supercooled spinning to obtain orientation‐induced crystallization at speeds lower than that for the high‐speed spinning technology. This is achieved by setting the nozzle temperature lower than the melting point for PET, making the polymer a supercooled fluidic liquid, and then spinning the supercooled. The experimental results show that high orientation and high crystallinity can be achieved at a spinning speed of 2500 m/min, which is in good comparison with a speed of 5000–6000 m/min to obtain similar degree of orientation and crystallinity in the high‐speed spinning. The properties of the as‐spun fibers obtained by supercooled spinning were analyzed, and a rational theoretical account for the supercooled spinning is explored. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3078–3082, 2006
Numerical simulation of localized cure of thermosensitive resin during thermo stereolithography process (TSTL)
Authors: Andrade S. R. , Jardini A. L. , Wolf Maciel M. R. , Maciel Filho R.
Published: August 2006

In this work, to analyze a type of rapid prototyping technique, a numerical model was developed that was able to simulate the heat transfer at thermosensitive polymeric material during cure by laser irradiation. The analysis was carried out as a transient thermal problem using the general‐purpose finite element software ANSYS. The technique analyzed was thermal stereolithography, which uses a CO2 laser beam to cure (solidify) thermosensitive liquid resins in a selective way to produce three‐dimensional parts. In this numerical analysis, the temperature distribution at thermoset material heated by a laser irradiation and its thermal properties are investigated. This resin is a high‐viscosity sample composed of epoxy resin, diethylenetriamine, and silica powder, which become highly crosslinked when irradiated by infrared laser. The localized curing becomes critical when the amount of silica and laser parameters are not appropriate. Bearing this in mind, this work intends, by applying the numerical method developed, to analyze the thermal behavior of resins in function of amount of silica and the laser radiation conditions, so that it is possible to have a knowledge on these variables so as to achieve a product with the required specifications. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2777–2783, 2006
Synthesis of dendrimer‐type poly(ethylene glycol) structures from plasma‐functionalized silicone rubber surfaces
Authors: Jiang H. , Manolache S. , Wong A. C. , Denes F. S.
Published: August 2006

PEG oligomers were covalently attached to nonequilibrium, low‐pressure, RF‐plasma‐functionalized silicone medical‐ and industrial‐grade silicon rubber surfaces, in the absence and presence of linear and branched polyglycidol spacer‐chain molecules. All surface‐modification reactions were carried out in a two‐step process involving an initial argon–plasma activation of the surface, followed by “in situ” reaction with dichlorosilane in the absence of the discharge, and the attachment of PEG molecules or the graft polymerization of polyglycidol structures, and the attachment of PEG molecules. The surface of substrates was analyzed after each reaction step, using ESCA, ATR‐FTIR, and AFM. It was found that PEG molecules directly attached to medical‐grade silicone rubber surface as brush‐type structures, and generate stronger antifouling characteristics in comparison to similar structures generated on food‐grade substrates. The presence of additives on the food‐grade silicon rubber surfaces that might be etched and removed during the postplasma washing cycles could contribute to a less efficient attachment of PEG molecules. Surfaces resulting from PEG molecules attached through intermediate, linear, and branched polyglycidol molecules did not reduce bacterial attachment. It is suggested that macromolecular entanglement might be responsible for this behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2324–2337, 2006
Properties of ligno‐cellulosic bilayered vegetable fabric from ridge gourd
Authors: Varada Rajulu A. , Venu Nadhan A. , Rama Devi R.
Published: August 2006

The two layers of bilayered vegetable fabric from ridge gourd were analyzed by FTIR, chemical, X‐ray, and thermogravimetric methods before and after alkali treatment. The morphology of the fabrics in the two layers, before and after alkali treatment, was also studied using SEM technique. The FTIR and chemical analyses indicated lowering of lignin and hemicellulose content by alkali treatment in the fabric of both layers. Further, the X‐ray diffraction revealed increase in crystallinity of the fabric by alkali treatment. The thermal stability of the fabric was also found to increase by alkali treatment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2338–2342, 2006