bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved performance of sulfonated polyarylene ethers for proton exchange membrane fuel cells
Authors: Xing D. , Kerres J. 
Published: September 2006

AbstractThe performances of polyarylene ethers and sulfonated polyarylene ethers having different backbone structures and sulfonated position were comparatively investigated focusing on the determination of the proton conductivity, thermal and chemical stability. The results indicated that the sulfone groups in polymer backbones are highly thermal stable. The sulfonic acid group at the meta‐sulfone position had better thermal, chemical stability and higher proton conductivity than those at the ortho‐ether and ortho‐sulfone position. The series of stability is meta‐sulfone sulfonated polyphenyl sulfone (SPSU) > ortho‐sulfone SPSU ≫ ortho‐ether SPSU. The knowledge of these parameters will lead to the synthesis of sulfonated arylene main‐chain ionomers that are optimized for application in fuel cells. Also different sulfonated polyphenyl sulfone‐4,4′‐biphenol/polybenzimidazole (SPSU‐BP/PBI) acid‐base crosslinked blend membranes have been studied. The SPSU/PBI crosslinked blend membranes had better mechanical stability than their parent membrane while maintaining good thermal stability and having suitable proton conductivity. Copyright © 2006 John Wiley & Sons, Ltd.
Gel polymer electrolyte prepared by in situ polymerization of MMA monomers in room temperature ionic liquid
Authors: Li Zhaohui , Jiang Jing , Lei Gangtie , Gao Deshu 
Published: September 2006

AbstractA kind of gel polymer electrolyte was prepared by in situ polymerization of methyl methacrylate (MMA) monomers in room temperature ionic liquid (RTIL), N‐butyl‐N′‐methylimidazolium hexafluorophosphate (BMIPF6). In comparison with other gel polymer electrolytes, it reveals excellent thermal stability over 260°C. The results of differential scanning calorimetry (DSC) measurements show that its glass transition temperature decreases with an increase in the ratio of RTIL to polymer matrix. At 25°C, the gel polymer electrolyte has 0.15 × 10−3 S cm−1 of ionic conductivity when the mass ratio of BMIPF6 to MMA monomers equals 1. Analysis of FT‐IR spectra suggests that there exists a hydrogen‐bonded interaction between BMIPF6 and poly(methyl methacrylate) (PMMA) polymer matrix in the polymer electrolyte. Copyright © 2006 John Wiley & Sons, Ltd.
On the calculation of energy produced by a PV grid‐connected system
Authors: Perpiñan O. , Lorenzo E. , Castro M. A. 
Published: September 2006

AbstractThis study develops a proposal of method of calculation useful to estimate the energy produced by a PV grid‐connected system making use of irradiance‐domain integrals and definition of statistical moment. Validation against database of real PV plants performance data shows that acceptable energy estimation can be obtained with first to fourth statistical moments and some basic system parameters. This way, only simple calculations at the reach of pocket calculators, are enough to estimate AC energy. Copyright © 2006 John Wiley & Sons, Ltd.
Influence of temperature during phosphorus emitter diffusion from a spray‐on source in multicrystalline silicon solar cell processing
Authors: Bentzen A. , Schubert G. , Christensen J. S. , Svensson B. G. , Holt A. 
Published: September 2006

AbstractWe have investigated the influence of diffusion temperature during phosphorus emitter diffusion from a spray‐on source on the performance of screen‐printed multicrystalline silicon solar cells. Because of the dual diffusion mechanism present at high concentration in‐diffusion of phosphorus in silicon, applying lower diffusion temperatures for a longer duration results in significantly enhanced penetration of the low concentration tail relative to the high concentration region. Moreover, we show that the sheet resistance of in‐diffused emitters from a high concentration source depends primarily on the extension of the high concentration region, thus significantly different emitter profiles can be manufactured without altering the sheet resistance considerably. Because of the enhanced tail penetration, emitters of a specified sheet resistance diffused at reduced temperatures can result in higher fill factors of screen‐printed solar cells due to diminution of Schottky type shunts. Furthermore, emitters diffused at lower temperatures for longer durations can yield a higher gettering efficiency, resulting in increased bulk recombination lifetime, and thus a higher internal quantum efficiency at long wavelengths. The deeper tail extension of low temperature emitters, however, causes increased absorption within the highly recombinative emitter, resulting in current losses due to a lower internal quantum efficiency at short wavelengths. Copyright © 2006 John Wiley & Sons, Ltd.
Kinetics and electron spin resonance study of the radical polymerization of n‐butyl acrylate mediated by a nitroxide precursor: C‐phenyl‐N‐tert‐butylnitrone
Authors: Sciannamea Valérie , Bernard Maxime , Catala Jean‐Marie , Jérôme Robert , Detrembleur Christophe 
Published: September 2006

AbstractThe C‐phenyl‐N‐tert‐butylnitrone/azobisisobutyronitrile pair is able to impart control to the radical polymerization of n‐butyl acrylate as long as a two‐step process is implemented, that is, the prereaction of the nitrone and the initiator in toluene at 85 °C for 4 h followed by the addition and polymerization of n‐butyl acrylate at 110 °C. The structure of the in situ formed nitroxide has been established from kinetic and electron spin resonance data. The key parameters (the dissociation rate constant, combination rate constant, and equilibrium constant) that govern the process have been evaluated. The equilibrium constant between the dormant and active species is close to 1.6 × 10−12 mol L−1 at 110 °C. The dissociation rate constant and the activation energy for the CON bond homolysis are 1.9 × 10−3 s−1 and 122 ± 15 kJ mol−1, respectively. The rate constant of recombination between the propagating radical and the nitroxide is as high as 1.2 × 109 L mol−1 s−1. Finally, well‐defined poly(n‐butyl acrylate)‐b‐polystyrene block copolymers have been successfully prepared. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6299–6311, 2006
Polyrotaxane derivatives. I. Preparation of modified polyrotaxanes with nonionic functional groups and their solubility in organic solvents
Authors: Araki Jun , Ito Kohzo 
Published: September 2006

AbstractVarious polyrotaxane modification reactions, such as methylation, hydroxy propylation, tritylation, acetylation, trimethylsilylation, phenylcarbamation, dansylation, and nitration, were examined to obtain polyrotaxane derivatives, in which various functional groups were attached to cyclodextrin moieties. Although the nitrate could not be obtained because of significant degradation of the polyrotaxane under the conditions examined, other derivatives were successfully prepared under moderate conditions. The introduction of these functional groups and their degree of substitution were assessed with Fourier transform infrared and NMR spectroscopy. The polyrotaxane derivatives thus obtained were soluble in various organic solvents other than the conventional solvents (dimethyl sulfoxide and aqueous NaOH) used for the unmodified polyrotaxane. That is, the solubility of the polyrotaxane was drastically changed by the examined modification reactions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6312–6323, 2006
Polymer having a trithiocarbonate moiety in the main chain: Application to reversible addition–fragmentation chain transfer controlled thermal and photoinduced monomer insertion polymerizations
Authors: Motokucho Suguru , Sudo Atsushi , Endo Takeshi 
Published: September 2006

AbstractA polymer having a trithiocarbonate moiety in its main chain was synthesized with a cyclic, five‐membered dithiocarbonate as a building block. The trithiocarbonate in the polymer acted as a reversible addition–fragmentation chain transfer reagent to mediate a controlled insertion polymerization of styrene into the polymer main chain, giving the corresponding sequence‐ordered polymer having a well‐defined polystyrene segment in the main chain. During the polymerization, the polystyrene segment in the main chain gained its molecular weight, which maintained a linear relationship with the conversion of styrene. The insertion polymerization of styrene was induced not only thermally but also by ultraviolet irradiation. This photoinduced polymerization was well controlled by the trithiocarbonate moiety to give the corresponding polymer, whose structure was virtually the same as that obtained by the thermal polymerization. © 2006 Wiley Periodicals, Inc. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6324–6331, 2006
New heterobicationic hemicyanine dyes: Synthesis, spectroscopic properties, and photoinitiating ability
Authors: Kabatc Janina , Jędrzejewska Beata , Pączkowski Jerzy 
Published: September 2006

AbstractThis article describes the synthesis, spectroscopic properties, and free‐radical photoinitiation ability of new heterobicationic hemicyanine dyes. A new synthetic strategy for the preparation of unsymmetrical cyanine dyes has been developed, based on 2‐methylbenzothiazole derivative quaternization by 3‐pyridinium‐1‐bromopropane bromide and subsequent condensation of the resulting product with p‐(N,N‐dimethylamino)benzaldehyde. The tested dyes possess in one molecule two quaternary nitrogen atoms; that is, they are heterobicationic in nature. Novel hemicyanine dyes have been tested as visible‐light photoinitiators of vinyl monomer polymerization. Heterobicationic hemicyanine dyes paired with n‐butyltriphenylborate anions are very efficient photoinitiators of the free‐radical polymerization of trimethylolpropane triacrylate when irradiated with the visible emission of an argon‐ion laser. The photoinitiating abilities of the novel photoredox pairs are compared with the photoinitiation properties of their monocationic equivalent {3‐methyl‐2‐[4‐(N,N‐dimethylamino)styryl]benzothiazolium n‐butyltriphenylborate} as well as a Rose Bengal derivative (a typical triplet‐state photoinitiator). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6345–6359, 2006
Novel polymers with a high carboxylic acid loading
Authors: Thomsen Anders D. , Malmström Eva , Hvilsted Søren 
Published: September 2006

AbstractClick chemistry has been used to prepare a range of novel polymers with pendant carboxylic acid side groups. Four azido carboxylic acids, either mono‐ or difunctional and aliphatic or aromatic, have been prepared and thoroughly characterized. Extensive model reactions with 1‐ethyl‐4‐hydroxybenzene, the simplest model for poly(4‐hydroxystyrene), and the four azido carboxylic acids have been conducted to establish the proper reaction conditions and provide an analytical frame for the corresponding polymers. Poly(4‐hydroxystyrene) moieties in three different polymers—poly(4‐hydroxystyrene), poly(4‐hydroxystyrene‐co‐methyl methacrylate), and poly(4‐hydroxystyrene‐b‐styrene)—have been quantitatively transformed into oxypropynes by the use of either Williamson or Mitsunobu strategies and subsequently reacted with the azido carboxylic acids. Detailed differential scanning calorimetry investigations of all the polymers in general exhibit [when poly(4‐hydroxystyrene) is a substantial part] significant changes in the glass‐transition temperature from the polar poly(4‐hydroxystyrene) (120–130 °C) to the much less polar alkyne polymers (46–60 °C). A direct correlation between the nature of the pendant groups in the derivatized polymers and the glass‐transition temperature has emerged: the aromatic carboxylic acids give high glass‐transition temperatures (90–120 °C), and the aliphatic carboxylic acids give lower glass‐transition temperatures (50–65 °C). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44:6360–6377, 2006
Triblock copolymer synthesis via controlled radical polymerization in solution using S‐tert‐alkyl‐N,N‐alkoxycarbonylalkyldithiocarbamate RAFT agents
Authors: Bussels Raf , Bergman‐Göttgens Christianne , Klumperman Bert , Meuldijk Jan , Koning Cor 
Published: September 2006

AbstractThis paper presents the solution homopolymerization, random and block copolymerization of acrylic monomers, mediated using an S‐(1,4‐phenylenebis(propane‐2,2‐diyl)) bis(N,N‐butoxycarbonylmethyldithiocarbamate) RAFT agent. Fair to good control was obtained over the solution homopolymerization of various acrylic monomers. Although inhibition periods were observed, nearly no retardation was found to occur. Satisfactory control was also obtained over the solution copolymerization of n‐butyl acrylate with methacrylic acid, mediated using this RAFT agent. Finally, triblock copolymer synthesis, starting from the macromolecular intermediates produced in the homo‐ and copolymerization experiments, was studied, and was shown to be successful. The observed relatively broad molar mass distributions could be explained by a partial decomposition of the dithiocarbamate‐based RAFT agent during synthesis and/or polymerization, for which strong indications were obtained by performing a careful MALDI‐ToF MS analysis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6419–6434, 2006
Nitroxide‐mediated controlled statistical copolymerizations of N‐isopropylacrylamide with N‐tert‐butylacrylamide
Authors: Gibbons Orla , Carroll William M. , Aldabbagh Fawaz , Yamada Bunichiro 
Published: September 2006

AbstractThe copolymerization of N‐isopropylacrylamide (NIPAM) and N‐tert‐butylacrylamide (TBAM) via conventional radical polymerization and nitroxide‐mediated polymerization (NMP) with N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)]nitroxide (SG1) was investigated. The monomer reactivity ratios were determined to be 0.58 and 1.00 for NIPAM and TBAM, respectively. The reactivities were approximately the same at 120 and 60 °C in N,N‐dimethylformamide (DMF) and toluene, respectively, for the conventional copolymerizations and in DMF at 120 °C for NMP. Controlled/living characteristics for NMP were achieved with a 2,2′‐azobisisobutyronitrile/SG1 bimolecular system and a unimolecular polystyrene [poly(STY)]–SG1 macroinitiator in the presence of excess free SG1. Block copolymers of poly(N‐isopropylacrylamide‐stat‐N‐tert‐butylacrylamide) [poly(NIPAM‐stat‐TBAM)] with styrene {poly(N‐isopropylacrylamide‐stat‐N‐tert‐butylacrylamide)‐block‐polystyrene [poly(NIPAM‐stat‐TBAM)‐block‐poly(STY)]} were obtained by chain extension of either poly(NIPAM‐stat‐TBAM)–SG1 with styrene or poly(STY)–SG1 with NIPAM/TBAM. A comparison of the number‐average molecular weight calculated from the end‐group content with the number‐average molecular weight measured by gel permeation chromatography for poly(NIPAM‐stat‐TBAM)‐block‐poly(STY)–SG1 indicated that nearly all poly(NIPAM‐stat‐TBAM) chains were capped by SG1 and were thus living. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6410–6418, 2006
Design and synthesis of multifunctional glycidyl ethers that undergo frontal polymerization
Authors: Crivello James V. 
Published: September 2006

AbstractAn investigation of the photoactivated cationic ring‐opening frontal polymerizations of a series of alkyl glycidyl ethers has been carried out with the aid of a novel technique, optical pyrometry. With this technique, the effects of the monomer structure on the frontal behavior of these monomers have been examined. Upon irradiation with UV light, the photopolymerizations of many alkyl glycidyl ethers display a prolonged induction period at room temperature as the result of the formation of long‐lived, relatively stable secondary oxonium ions. The input of only a small amount of thermal activation energy is required to induce the further reaction of these species with a consequent autoaccelerated exothermic ring‐opening polymerization. Photoactivated frontal polymerizations have been observed for both mono‐ and polyfunctional alkyl glycidyl ether monomers. The ability of monomers to exhibit frontal behavior has been found to be related to their ability to stabilize the secondary oxonium ion intermediates through multiple hydrogen‐bonding effects to the ether groups present in the molecule. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6435–6448, 2006
Dielectric and conductivity processes in poly(ethylene terephthalate) and poly(ethylene naphthalate) homopolymers and copolymers
Authors: Psarras G. C. , Beobide A. Soto , Voyiatzis G. A. , Karahaliou P. K. , Georga S. N. , Krontiras C. A. , Sotiropoulos J. 
Published: September 2006

AbstractElectrical relaxation and conductivity processes in amorphous and semicrystalline poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) homopolymers and certain PET/PEN copolymers have been studied by means of dielectric spectroscopy. Homopolymers and copolymers able to crystallize were subjected to successive thermal runs to investigate the influence of the thermal history upon the morphology and the electrical behavior of the polymeric systems. The morphology of the untreated as well as the heat‐treated specimens was determined by means of Differential Scanning Calorimetry (DSC). All samples exhibit β‐relaxation process, due to local motions of the CO polar side groups, and α‐relaxation process associated to the glass/rubber transition. In the PEN spectrum an additional, subglass, mode was recorded, most probably attributed to cooperative motions of the naphthalene groups. Finally, the dynamic nature of the crystallization process is expressed via the over glass transition mode and the temperature dependence of dc conductivity recorded in amorphous PET, PEN, and PET/PEN (85/15) (wt/wt) samples. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3078–3092, 2006
Extended‐chain crystals in high‐pressure crystallized poly(ethylene terephthalate)/bisphenol a polycarbonate blends
Authors: Lu Jun , Huang Rui , Chen Yong , Li Liangbin 
Published: September 2006

AbstractMorphologies of extended‐chain crystals with different characteristics were observed with scanning electron microscopy (SEM) in the high‐pressure crystallized polyethylene terephthalate/polycarbonate (PET/PC) blends. The crystals memorize their nucleation and growth process, which reveal an involvement of different mechanisms simultaneously. The presence of sliding diffusion during crystal thickening is indicated by a wedge shape of some crystals, while bent crystals suggest the occurrence of transesterification in the formation of the large extended‐chain crystals. The observation of two morphological features on one group of crystals shows that two mechanisms may work simultaneously. The connection between folded‐chain and extended‐chain crystals is demonstrated by the S‐shaped extended‐chain crystals as well as their direct morphological connection observed with SEM. Though transesterification plays the essential role in the formation of the large crystals, which acts in different aspects during the process, the thermodynamic driving force is the enthalpy gain associated with large crystals. This is a high‐pressure self‐assembly with a coupling between crystallization and transesterification, which may be instructive to grow such large crystals in similar polymer systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3148–3156, 2006
Tb(III)‐modified properties of thermosensitive core–shell microspheres
Authors: Yin Weiqing , Jiang Ling , Wang Yanjia , Huang Xiaohua 
Published: September 2006

AbstractA novel functional complex with the thermosensitive, magnetic, and fluorescent properties of poly(N‐isopropylacrylamide)‐grafted poly(N‐isopropylacrylamide‐co‐styrene) (PNNS) microspheres and Tb(III), PNNS–Tb(III), has been synthesized and characterized with different techniques. When PNNS with a core–shell structure interacts with Tb(III), Tb(III) mainly bonds to oxygen of the carbonyl groups of PNNS, forming the novel PNNS–Tb(III) complex. PNNS shows antiferromagnetic behavior, whereas the PNNS–Tb(III) complex exhibits paramagnetic behavior. The saturation magnetization is approximately 50 times higher than that of PNNS. The fluorescence intensity of the PNNS–Tb(III)complex at 545 nm is enhanced as much as 223 times in comparison with that of pure Tb(III). The novel magnetic and fluorescent properties of the PNNS–Tb(III) complex may be useful in biomedicine and fluorescence systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3121–3127, 2006
Diagnosis of congenital CMV infection via dried blood spots
Authors: Barbi Maria , Binda Sandro , Caroppo Simona 
Published: September 2006

AbstractCytomegalovirus (CMV) infection is the most frequent congenital infection in humans and can cause permanent damage—particularly neurological—in about 20% of those infected, with or without symptoms at birth. Laboratory diagnosis is essential on account of the relatively non‐specific clinical manifestations in symptomatic newborns but also because of the high frequency of asymptomatic cases that are nevertheless at risk of lesions later in life. However, these tests need samples taken within 3 weeks of birth to distinguish congenital infection from the more common, but clinically benign, perinatal infection.Tests for viral DNA have proved a valid means of diagnosing congenital CMV infection in neonatal blood dried on paper (DBS) widely used in screening for metabolic and genetic diseases, as an alternative to the conventional urine culture method. The DBS test is simpler, faster and less costly than viral isolation; in addition the samples can be safely stored for long periods, so diagnosis can be made even after several years. The sensitivity and specificity of the DBS test, compared to the reference method, have been reported to range between 71 and 100% and 99 and 100%, respectively, depending on the different studies and diagnostic criteria applied.The most interesting applications reported so far involve retrospective determination of the impact of congenital CMV in sensorineural deafness, abnormalities of cortical development, neonatal cholestasis and surveys of the prevalence of this infection in various populations. The test might be useful in the future for neonatal screening with a view to treating neonates and so avoiding the damage this disease can cause. Copyright © 2006 John Wiley & Sons, Ltd.
Defining business process flexibility with the help of invariants
Authors: Regev Gil , Bider Ilia , Wegmann Alain 
Published: September 2006

AbstractEnterprise survival is about maintaining an identity that is separate from other enterprises. We define flexibility as the ability to change without losing identity. The identity of an enterprise can be analyzed as a set of norms and beliefs about these norms held by its stakeholders, such as customers, employees, suppliers, and investors. Business processes and their support systems maintain invariants that are the result of compromises between the often conflicting norms and beliefs of these stakeholders. We formalize these invariants as values in a state space. Identifying a minimum set of invariants provides a basis for defining flexible processes and support systems. We illustrate the use of this framework with production business process support (BPS) systems. Copyright © 2006 John Wiley & Sons, Ltd.