bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the reaction of organotin phenoxides with ethyl propiolate catalysed by triethylamine and tin(IV) chloride
Authors: Kinart Wojciech J. , Kinart Andrzej 
Published: February 2007

AbstractDifferent tributyltin phenoxides react at room temperature with ethyl propiolate in benzene, in the presence of tin(IV) chloride, triethylamine and their mixture to give the derivatives of 3‐phenoxyacrylic acid ethyl ester. Exceptionally, 3‐(2‐hydroxyphenyl)acrylic acid ethyl ester and 3‐(2‐hydroxy‐5‐methylphenyl)acrylic acid ethyl ester have been obtained from the reaction of tributylphenoxytin and tributyl(p‐tolyloxy)tin, respectively catalysed by SnCl4, and they have been easily hydrolysed to coumarin and 6‐methylcoumarin. Copyright © 2007 John Wiley & Sons, Ltd.
Kinetics of isothermal and nonisothermal crystallization of nylon 1313
Authors: Wang Yudong , Liu Minying , Wang Zhimin , Li Xiaoguang , Zhao Qingxiang , Fu Peng‐Fei 
Published: February 2007

AbstractThe crystallization process of a new polyamide, nylon 1313, from the melt has been thoroughly investigated under isothermal and nonisothermal conditions. During isothermal crystallization, relative crystallinity develops in accordance with the Avrami equation with the exponent n ≈ 2 based on DSC analysis. Under nonisothermal conditions, several different analysis methods were used to elucidate the crystallization process. The Avrami exponent n is greater in the isothermal crystallization process, indicating that the mode of nucleation and the growth of the nonisothermal crystallization for nylon 1313 are more complicated, and that the nucleation mode might include both homogeneous and heterogeneous nucleation simultaneously. The calculated activation energy is 214.25 kJ/mol for isothermal crystallization by Arrhenius form and 135.1 kJ/mol for nonisothermal crystallization by Kissinger method, respectively. In addition, the crystallization ability of nylon 1313 was assessed by using the kinetic crystallizability parameters G. Based on this parameter, the crystallizability of many different polymers was compared theoretically. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1415–1422, 2007
Ultrasound‐assisted coating of nylon 6,6 with silver nanoparticles and its antibacterial activity
Authors: Perkas N. , Amirian G. , Dubinsky S. , Gazit S. , Gedanken A. 
Published: February 2007

AbstractA silver/nylon 6,6 nanocomposite containing 1 wt % metallic silver has been produced from an aqueous solution of silver nitrate in the presence of ammonia and ethylene glycol by an ultrasound‐assisted reduction method. The structure and properties of nylon 6,6 coated with silver have been characterized with X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, energy‐dispersive X‐ray, X‐ray photoelectron spectroscopy, Raman spectroscopy, and diffused reflection spectroscopy measurements. The nanocrystals of pure silver, 50–100 nm in size, are finely dispersed on the polymer surface without damaging the nylon 6,6 structure. This silver–nylon nanocomposite is stable to many washing cycles and thus can be used as a master batch for the production of nylon yarn by melting and spinning processes. The fabric knitted from this yarn has shown excellent antimicrobial properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1423–1430, 2007
Effect of fullerenes on the structure and properties of linear and crosslinked polyesterurethane ureas
Authors: Olkhov Y. A. , Jurkowski B. 
Published: February 2007

AbstractSmall concentrations up to 10−6 mol/cm3 of C60 fullerenes influence on both the molecular and topological structures changing at synthesis and the related mechanical properties of linear (pseudonetworked) and crosslinked polyester urethane ureas (PEUU). A crosslinked PEUU was synthesized on the base of poly(oxypropylene) macrodiisocyanate (POPMDIC) and 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane (MOCA) with virtually an equimolar ratio of amine and isocyanate groups, but the linear polymer was obtained with twofold molar excess of amine groups. Fullerenes change the network density, the share of the physical branching junctions and molecular weight distribution (MWD) of the chain segments between the networking junctions. Additionally, molecular weight and the polydispersity index increase with C60 concentration in the reaction blend. This evidences to a branching role of C60 during their interaction with terminating amine groups. An influence of MWD of the chain segments between the networking junctions on tensile strength of the crosslinked and linear polymers was assumed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1431–1442, 2007
Sulfonated poly(ether ether sulfone) copolymers for proton exchange membrane fuel cells
Authors: Wang Zhe , Li Xianfeng , Zhao Chengji , Ni Hongzhe , Na Hui 
Published: February 2007

AbstractNovel aromatic sulfonated poly(ether ether sulfone)s (SPEESs) with tert‐butyl groups were synthesized by aromatic nucleophilic polycondensation of disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenylsulfone (SDCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS), and tert‐butylhydroquinone (TBHQ). The resulting copolymers showed very good thermal stability and could be cast into tough membranes. The morphology of the membranes was investigated with atomic force microscopy. The proton conductivity of SPEES‐40 membranes increased from 0.062 S/cm at 25°C to 0.083 S/cm at 80°C, which was higher than the 0.077 S/cm of Nafion 117 under the same testing conditions. These copolymers are good candidates to be new polymeric electrolyte materials for proton exchange membrane fuel cells. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1443–1450, 2007
pH‐controlled uphill transport of boric acid through a poly(vinyl alcohol) (PVA) membrane
Authors: Shimada Toshio , Iizuka Atsushi , Shiojiri Kazuhiro , Yamasaki Akihiro , Yanagisawa Yukio 
Published: February 2007

AbstractThe uphill transport of boric acid in aqueous solutions through a thermal‐crosslinked poly(vinyl alcohol) (PVA) membrane was investigated. A normal permeation caused by the concentration difference of the boron along the PVA membrane was observed for equal pH conditions at both sides of the membrane, and higher flux was observed under an acidic condition at pH = 5.0 than under a basic condition at pH = 10.0. When the pH of one side is kept pH = 5.0 (acid side) and the other side was kept at pH = 10.0 (base side), uphill transport of boric acid from the acid side to the base side was observed under an equal initial concentration of both sides. Such an uphill transport was also observed against the concentration difference under the condition in which the initial concentration of the base side was higher than that of the acid side. The uphill transport could be explained by the difference in the permeation rates through the PVA membrane between B(OH)3, the dominant form under lower pH, and B(OH)4−, the dominant form under higher pH, which makes a complex with diols in PVA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1451–1455, 2007
Phase structure and thermal stability of crosslinked polyurethane elastomers based on well‐defined prepolymers
Authors: Król Piotr , Pilch‐Pitera Barbara 
Published: February 2007

AbstractTaking advantage of the DSC method, general procedures were presented for qualitative and quantitative evaluation of the phase separation degree and the crystalline phase content in polyurethane elastomers with well‐defined structures. Those elastomers were obtained not only in a typical one‐step method but also in the prepolymer method with the use of urethane oligomers with controlled molecular weight distribution (MWD). Prepolymers with well defined chain structures and narrow distributions of their molecular weights (MWD) Mw/Mn = 1.1–1.3 were produced in a multistage method, i.e., in step‐by‐step polyaddition of 2,4‐ and 2,6‐TDI with polyoxyethylenediols or with polycaprolactonediols of varied molecular weights. Isocyanate oligomers obtained at individual stages were then crosslinked with triethanolamine, whereas hydroxyl‐terminated oligomers were crosslinked with 4,4′,4″‐triphenylmethane triisocyanate (Desmodur RE). The obtained polyurethane elastomers were found to be characterized by the presence of five phases: soft phase consisted of flexible polyol‐type segments, crystalline phase made of soft segments, crystalline and amorphous hard phase made of hard segments, and intermediate phase, which was a composition of the soft and hard segments. The polyurethanes obtained out of prepolymers with defined MWD were characterized by better phase separation of the soft segments and increased structural order inside the hard phase as well as by better thermal stability than polyurethanes obtained from the typical one‐step method. The structural effects were also discussed on the thermal properties of the synthesized elastomers as analyzed by the TG and DTA methods. © 2007 Wiley Periodicals, Inc. J Appl PolymSci 104: 1464–1474, 2007
Pore collapse during the fabrication process of rubber‐like polymer scaffolds
Authors: Diego Raúl Brígido , Ribelles José Luis Gómez , Sánchez Manuel Salmerón 
Published: February 2007

AbstractRubbery polymer scaffolds for tissue engineering were produced using templates of the pore structure. The last step in the fabrication process consists of dissolving the template using a solvent that, at the same time, swells the scaffolding matrix that was a polymer network. Sometimes the polymer matrix is stretched so strongly that when the solvent is eliminated, i.e., the network is dried, it shrinks and is not able to recover its original shape and, consequently, the porous structure collapses. In this work we prepared, using the same fabrication process (the same template and the same solvent), a series of polymer scaffolds that results in collapsed or noncollapsed porous structures, depending on the polymer network composition. We explain the collapse process as a consequence of the huge volume increase in the swelling process during the template extraction due to the large distance between crosslinking points in the scaffolding matrix. By systematically increasing the crosslinking density the porous structure remains after network drying and the final interconnected pores were observed. It is shown that this problem does not take place when the scaffolding matrix consists of a glassy polymer network. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1475–1481, 2007
Cation exchange resin cum polymeric indicator based on sulfonated styrene/methyl acrylate copolymers
Authors: Ratna D. , Dalvi V. , Chakraborty B. C. 
Published: February 2007

AbstractStyrene (ST)/methyl acrylate (MA) copolymers, having various MA contents (0–50 wt %), were synthesized in the form of a crosslinked bead and characterized by FTIR, solid state nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. The copolymers were sulfonated using concentrated sulfuric acid. The copolymers with a higher MA content (20 wt % or above) undergo sulfonation even at room temperature, and higher temperature was required for the completion of sulfonation in case of the samples having lower MA content. This has been explained in terms of the polarity and porosity of the beads as has been analyzed by scanning electron microscope (SEM). The sulfonated copolymer beads show built‐in acid–base indicator property: yellow color in an acid medium changes to intense pink color at the equivalence point. FTIR and NMR studies clearly indicate that intramolecular cyclization takes place during sulfonation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1517–1522, 2007
Comparison of the curing kinetics of a DGEBA/acid anhydride epoxy resin system using differential scanning calorimetry and a microwave‐heated calorimeter
Authors: Navabpour P. , Nesbitt A. , Mann T. , Day R. J. 
Published: February 2007

AbstractThe cure of an epoxy resin system, based upon a diglycidyl ether of bisphenol‐A (DGEBA) with HY917 (an acid anhydride hardener) and DY073 (an amine–phenol complex that acted as an accelerator), was investigated using a conventional differential scanning calorimeter and a microwave‐heated power‐compensated calorimeter. Dynamic cure of the epoxy resin using four different heating rates and isothermal cure using four different temperatures were carried out and the degree of cure and reaction rates were compared. The cure kinetics were analyzed using several kinetics models. The results showed different activation energies for conventional and microwave curing and suggested different reaction mechanisms were responsible for curing using the two heating methods. Resins cured using conventional heating showed higher glass transition temperatures than did those cured using microwave heating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2054–2063, 2007
Flame retardancy and char microstructure of nylon‐6/layered silicate nanocomposites
Authors: Shanmuganathan Kadhiravan , Deodhar Sarang , Dembsey Nicholas , Fan Qinguo , Calvert Paul D. , Warner Steven B. , Patra Prabir K. 
Published: February 2007

AbstractWe investigated the effect of organically modified clay alone and in combination with zinc borate on the thermal/flammability behavior of nylon‐6 nanocomposites. Differential thermogravimetric analysis indicated that the peak decomposition temperature was not affected by the addition of clay, but the rate of weight loss decreased with increase in clay concentration. Nanocomposite films of approximately 0.5 mm thickness with 2.5 and 5 wt % clay burned for almost the same duration as neat nylon‐6 but with reduced dripping in horizontal flame test. The 10 wt % clay nanocomposite sample burned without any dripping and the flame spread rate was reduced by 25–30%. Zinc borate/clay containing nanocomposite developed into a very good intumescent system in cone calorimeter test, swelling about 10–13 mm height prior to ignition forming a cellular char structure. This was found to be an effective composition in reducing the heat release and mass loss rate of nylon‐6 by about 65% and at par with 10 wt % clay nanocomposite. Flame retardant behavior could be attributed to distinct char morphologies observed through scanning electron microscopy. Fourier transform infrared spectroscopy of the 10 wt % clay nanocomposite char showed the presence of amides, indicating possible residual polymer within the shielded char. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1540–1550, 2007
Design, synthesis and characterization of novel electroactive polyamide with amine‐capped aniline pentamer in the main chain via oxidative coupling polymerization
Authors: Chao Danming , Ma Xiaobo , Lu Xiaofeng , Cui Lili , Mao Hui , Zhang Wanjin , Wei Yen 
Published: February 2007

AbstractBy oxidative coupling polymerization of the macromonomer of oligoaniline and p‐phenylenediamine we have prepared a novel electroactive polyamide, exhibiting well‐defined molecular structure, interesting spectroscopic and electrochemical properties. The well‐defined molecular structure of the electroactive polyamide was confirmed by FTIR, NMR spectroscopy, elemental analysis and X‐ray powder diffraction (XRD) and the resulting polyamide exhibit an enhanced solubility in most of the organic solvents as compared with polyaniline. The UV–Vis spectra were used to monitor the chemical oxidation process of the reduced polyamide. Electrochemical activity of the polyamide was tested in 1.0M H2SO4 aqueous solution and it shows three redox peaks, which is different from the polyaniline. Moreover, the thermal properties of the polyamide were evaluated by thermogravimetric analysis (TGA) and it shows moderate thermal resistance in the N2 atmosphere. Its electrical conductivity is about 1.04 × 10−4 S cm−1 at room temperature upon preliminarily protonic‐doped experiment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1603–1608, 2007
Crystallization behavior of PP/PP‐g‐MAH/GFR PA66 blends: Establishment of their continuous‐cooling‐transformation of relative crystallinity diagrams
Authors: Safidine Z. , Fellahi S. , Frick A. 
Published: February 2007

AbstractPolypropylene/polypropylene‐grafted‐maleic anhydride/glass fiber reinforced polyamide 66 (PP/PP‐g‐MAH/GFR PA 66) blends‐composites with and without the addition of polypropylene‐grafted‐maleic anhydride (PP‐g‐MAH) were prepared in a twin screw extruder. The effect of the compatibilizer on the thermal properties and crystallization behavior was determined using differential scanning calorimetry analysis. The hold time was set to be equal to 5 min at 290°C. These conditions are necessary to eliminate the thermomechanical history in the molten state. The crystallization under nonisothermal conditions and the plot of Continuous‐Cooling‐Transformation of relative crystallinity diagrams of both PP and PA 66 components proves that PP is significantly affected by the presence of PP‐g‐MAH. From the results it is found that an abrupt change is observed at 2.5 wt % of PP‐g‐MAH as a compatibilizer and then levels off. In these blends, concurrent crystallization behavior was not observed for GFR PA66. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1620–1626, 2007
Radiopacity evaluation of Bis‐GMA/TEGDMA/opaque mineral filler dental composites
Authors: Amirouche A. , Mouzali M. , Watts D. C. 
Published: February 2007

AbstractThe purpose of this work was to determine radiopacity values of composites based on (Bis‐GMA/TEGDMA) monomers, at varying monomer compositions: (25/75), (50/50), and (75/25), mixed with five different radiopacifying filler agents: BaO, BaSO4, La2O3, ZrO2, and SrO at varying loadings ranging from 0 to 80 wt %. The radiopacity of four commercial dental composites were also evaluated and used as a comparative data. Following standard radiographic technique, X‐ray radiography of 2.5 mm thickness dental composite specimens along with pure aluminum step‐wedge, a reference, were performed. The optical density of specimens was measured using a transmission densitometer and the radiopacity values of samples were expressed in term of equivalent thickness of aluminum per mm thickness of material. The lanthanum oxide filler containing composites, which is a new radiopacifying agent, exhibited the greatest radiopacity levels than all other composites, for all monomer and filler loadings studied. The radiopacity values of these composites were greater than that of human dental enamel. Strontium oxide containing composites were less radiopaque than other materials especially in the case of composites based on (Bis‐GMA/TEGDMA): (25/75). The composites containing more than 10 wt % of BaO, BaSO4, and ZrO2 for monomer compositions of (75/25) and (50/50) had radiopacity values greater than that of enamel. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1632–1639, 2007
Tensile, flow, and thermal properties of CaCO3‐filled LDPE/LLDPE composites
Authors: Liang Ji‐Zhao 
Published: February 2007

AbstractCalcium carbonate (CaCO3)‐filled low‐density polyethylene (LDPE)/linear low‐density polyethylene (LLDPE) composites were fabricated by means of a twin‐screw extruder, and the tensile mechanical properties of the tubing with thickness of 0.5 mm made from these composites were measured at room temperature to identify the effect of the filler concentration on the properties of these composites. The results showed that the tensile elastic modulus increased roughly linearly with increasing weight fraction (ϕf) of the fillers. The tensile fracture strength (σb) along longitudinal direction was obviously higher than that along transverse direction under the same test conditions, especially at higher filler concentration. The values of σb of the specimens along both the two directions achieved minimum at ϕf = 20%. Furthermore, the melt flow rate (MFR) and heat enthalpy (ΔH) of the composite materials were measured. It was found that both the MFR and the ΔH decreased with the addition of ϕf. The ΔH for the composite with LDPE/LLDPE ratio of 70/30 was higher than that of the composite with LDPE/LLDPE ratio of 50/50 at the same filler concentration, but contrary to the MFR. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1692–1696, 2007
Morphologies and properties of cured epoxy/brominated‐phenoxy blends
Authors: Yokoyama Naoki , Nonaka Yasushi , Kurata Toshiharu , Sakai Shunsuke , Takahashi Shinya , Kasemura Tomoyuki 
Published: February 2007

AbstractMorphologies of cured epoxy/brominated‐phenoxy blends were observed by scanning transmission electron microscopy (STEM) and energy dispersive X‐ray fluorescence spectroscopy (EDX). When brominated‐phenoxy content was 30 wt %, cocontinuous phase structures between cured epoxy and brominated‐phenoxy were found. Since every loss tangent (tan δ) curve as a function of temperature on dynamic mechanical analysis (DMA) showed 2 peaks at 128°C and 155°C respectively, cured epoxy phases and brominated‐phenoxy phases were incompatible together and Tgs of cured epoxy phases were not decreased. Tensile strength and tensile elongation of the cured blends were increased together. T‐peel adhesion strength and the lap‐shear adhesion strength were also increased together. These phenomena could be due to the cocontinuous structures consisted by the rigid cured epoxy phases of thermosets and ductile the brominated‐phenoxy phases of thermoplastics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1702–1713, 2007
Thermoanalytical, spectroscopic, and morphological study of poly(ethylene glycol)/poly(2‐acrylamido‐2‐methylpropanesulfonic acid‐co‐N‐isopropylacrylamide) semi‐interpenetrating network gels
Authors: Zhang Chi , Easteal Allan J. 
Published: February 2007

AbstractNovel poly(ethylene glycol)/poly(2‐acrylamido‐ 2‐methylpropanesulfonic acid‐co‐N‐isopropylacrylamide) semi‐interpenetrating network gels were synthesized with free‐radical initiation at 70°C and characterized with differential scanning calorimetry, Fourier transform infrared and X‐ray photoelectron spectroscopy, X‐ray diffraction, and scanning electron microscopy. The first thermal decomposition peaks for semi‐interpenetrating network gels with various proportions of 2‐acrylamido‐2‐methylpropanesulfonic acid and N‐isopropylacrylamide were in the range of 278–289°C, whereas for poly (2‐acrylamido‐2‐methylpropanesulfonic acid‐co‐N‐isopropylacrylamide) copolymer gels with corresponding proportions of the comonomers, decomposition began at about 203°C. A significant proportion of the amide groups in the semi‐interpenetrating network gels with a high proportion of 2‐acrylamido‐2‐methylpropanesulfonic acid were found to be protonated as a result of the relatively strong acid strength of 2‐acrylamido‐2‐methylpropanesulfonic acid. The surface morphology of the dried gels varied with the relative proportions of the comonomers and was significantly different for the semi‐interpenetrating network gels and corresponding copolymer gels. Strong hydrophobic and hydrogen‐bonding interactions between poly (ethylene glycol) with an average molecular weight of approximately 6000 g/mol and the copolymer network were responsible for different thermal behaviors of the poly(2‐acrylamido‐2‐methylpropanesulfonic acid‐co‐N‐isopropylacrylamide) copolymer gels and the semi‐interpenetrating network gels. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1723–1731, 2007