bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study of the photopolymerization kinetics of methyl methacrylate using novel benzophenone initiators
Authors: George Beena , Dhamodharan R 
Published: August 2002

AbstractA series of novel bifunctional photoinitiators with benzophenone moieties were synthesized. Characterization of these molecules was performed using IR, UV, 1H NMR, 13C NMR and mass spectroscopy. Photopolymerization of methyl methacrylate, a model acrylate‐type monomer, was carried out with the bifunctional benzophenone molecules functioning as the photoinitiator and triethylamine as the co‐initiator. The progress of the polymerization was followed by dilatometry. The resulting plots of monomer conversion with time were used to evaluate the initial rates of polymerization. The relative enhancement/lowering of the rates of polymerization, with respect to benzophenone as the model photoinitiator, are interpreted in terms of the structure, and the photophysics of the initiator evaluated by nanosecond laser flash photolysis.© 2001 Society of Chemical Industry
In situ FT‐IR and DSC investigation on the cure reaction of the dicyanate/diepoxide/diamine system
Authors: Lin Rong‐Hsien , Hsu Jiun‐Hsien 
Published: August 2002

AbstractCure reactions of a liquid aromatic dicyanate ester (1,1′‐bis(4‐cyanatophenyl)ethane, BEDCy) with a liquid bisphenol A epoxide (2,2‐bis(4‐glycidyloxyphenyl)propane, BADGE) and 4,4′‐diaminodiphenyl sulfone (DDS) were studied through correlation of the in situ FT‐IR spectroscopy and DSC in dynamic scanning mode. Before this system was examined, cure reactions of precursory systems of BADGE/DDS, BEDCy/BADGE and BEDCy/DDS were investigated separately. Cure reaction paths for each system are proposed. Some reactions in the precursory systems, such as polycyclotrimerization of dicyanate to form sym‐triazine and formation of alkyl isocyanurate, were not observed in the combined curing system BEDCy/BADGE/DDS. Four principal reaction paths are proposed for this curing system: (1) formation of oxazoline from the reaction between the epoxide and cyanate group; (2) reaction of epoxide with primary amine to form a hydroxyl group; (3) reaction of epoxide with the hydroxyl group to form an ether linkage; and (4) rearrangement of oxazoline to form oxazolidinone. Two distinct, but somewhat overlapping, exothermic peaks were observed on the DSC thermogram. The lower temperature peak on the DSC thermogram was primarily contributed by the first reaction path, whereas the higher temperature peak can mainly be attributed to the reaction paths 2, 3 and 4.© 2001 Society of Chemical Industry
Reactivity ratios during radiation‐induced grafting of comonomer mixtures onto polyester fabrics
Authors: El‐Naggar A M , Zohdy M H , Sahar S M , Allam E A 
Published: August 2002

AbstractRadiation‐induced grafting of binary mixtures of acrylonitrile (AN)/styrene (S) and acrylamide (AAm)/styrene (S) onto polyester fabric (PET) has been investigated. Synergism during radiation grafting was investigated by determining the graft yield fraction for each monomer in the final graft copolymer. Moreover, by knowing the mole fraction of each monomer in the grafting solution, the reactivity ratio of the individual monomers in the comonomer mixture during graft copolymerization could be determined: in the case of AN/S comonomer mixture, the calculated reactivity ratios for AN and S are 0.04 and 0.05, respectively; the calculated reactivity ratios of AAm and S in their comonomer mixture are 1.82 and 0.41, respectively.© 2001 Society of Chemical Industry
The growing photovoltaic market in India
Authors: Chaurey Akanksha 
Published: August 2002

AbstractGrowth of the Indian photovoltaic industry, which produces 58 MWp at present, is influenced by global market trends, owing to the cost of the technology. It is also driven by local government initiatives and policies. The current structure of the market and its various segments is discussed, with the objective of studying the overall growth potential. A growth of 250 MWp in the next ten years is projected, with annual production reaching 35 MWp by 2010. In order to achieve the projected market volume, specific barriers related to technology and market development are identified, and enabling mechanisms are suggested. The Indian experience of barriers to adoption of PV technology, and their removal, are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Energy demand in solar home systems: the case of the communities in Ribeira Valley in the state of São Paulo, Brazil
Authors: Morante Federico , Zilles Roberto 
Published: August 2002

AbstractAn account is given of research on energy demand with solar home systems (SHSs) and the analysis of results of a field survey of 18 families located in 4 communities in the Ribeira Valley, on the southern coast of the State of São Paulo, Brazil. These families' energy consumption was measured over a one‐year period and, in order to do so, equipment that could determine the daily energy requirements in Ampere hour units was developed. The measurement instrument was coupled to existing (SHSs) in these communities and the data collection involved direct user participation. Data collection was done by hand and was intended to provide an interrelationship among the system, the user, and the researcher. The data provided social and cultural information related to the energy use in addition to essentially technical data. Through this methodology it was confirmed that energy demand is related to a number of factors which were not predicted before the survey. It was also confirmed that the people's behavior is reflected in the operation of the photovoltaic system as a whole. The results show that 55% of the SHSs researched showed consumption below 3 kW h/month. Copyright © 2001 John Wiley & Sons, Ltd.
Gas‐phase elimination reactions of 4‐arylideneimino‐1,2,4‐triazol‐3(2H)‐ones and their 3(2H)‐thione analogues
Authors: Al‐Awadi Nouria , Ibrahim Yehia , Kaul Kamini , Dib Hicham 
Published: August 2002

Abstract4‐Arylideneimino‐1,2,4‐triazol‐3(2H)‐ones (1–4) and their thio analogues (5–8) were pyrolysed in the gas phase. The reactions were homogeneous and free from catalytic and radical pathways. Analysis of the pyrolysate showed the elimination products to be substituted benzonitriles and the corresponding 3‐hydroxy‐1,2,4‐triazoles and their thio analogues. The kinetic results and product analysis lend support to a reaction pathway involving a six‐membered transition state. At 500 K, the thiooxotriazoles 5–8 were found to be 103‐fold more reactive than the corresponding oxotriazoles 1–4. The reactivities of the 2‐oxotriazoles were compared with those of the substituted 2‐oxopyridine‐3‐carbonitriles. Copyright © 2001 John Wiley & Sons, Ltd.
A non‐topotactical thermal rearrangement without change of the macroscopic crystal shape
Authors: Kaupp G. , Schmeyers J. , Kato M. , Tanaka K. , Harada N. , Toda F. 
Published: August 2002

AbstractThe solid‐state thermal transformation of rac‐3,8‐di(tert‐butyl)‐1,5,6,10‐tetraphenyldeca‐3,4,6,7‐tetraene‐1,9‐diyne (1) into 4,5,9,10‐tetraphenyltricyclo[6.2.0.02,6]deca‐1,3,5,7,9‐pentaene (3) was investigated by x‐ray crystallography and atomic force microscopy (AFM) on two different faces. The enantiopure crystals of 1 that were picked from the conglomerate were monoclinic in the chiral space group C2 (No. 5) and were refined to an R‐factor of 0.0375. The monolayers stack in a straight manner without displacement leaving (001) cleavage planes. The layered structure is seen in AFM traces at certain stages of the reaction. The overall shape of single crystals of 1 does not change even though they turn deeply blue–green at 140–150 °C. However, the initial roughness in the micrometer region is flattened out or thoroughly rearranged by long‐range molecular movements giving phase rebuilding and phase transformation without detachment of the product from the parent crystal. Thus, the chemical reaction is limited to the surface region and to internal cracks of the crystal. A topotactical transformation is experimentally excluded and cannot be modelled at the given crystal structure. The chemical yield depends on the crystal size and is significant. The thermochrome 3 reverts to 1 but only in the outer surface region at anaerobic storage, whereas the known solid‐state oxidations occur in air. The topographic differences of these processes were traced with AFM. The release of strain in the surface region is evidenced by anisotropic crack formation that initially follows the crystal packing of 1 and could be imaged and compared with an ordinary microscope after the thermal reversion or oxidation. Copyright­© 2001 John Wiley & Sons, Ltd.
Experimental and theoretical determination of the dipole polarizability of dibenzothiophene
Authors: Soscún Humberto , Alvarado Ysaías , Hernández Javier , Hernández Paola , Atencio Reinaldo , Hinchliffe Alan 
Published: August 2002

AbstractThe dipole polarizability of dibenzothiophene is reported, which was measured experimentally by refractometry techniques, and evaluated theoretically with ab initio and density functional theory (DFT) methods in the 1A′ electronic ground state. The experimental polarizability was determined from measurements of the refraction index of dibenzothiophene in CCl4‐diluted solutions at five different frequencies to obtain the dispersion curve. The static polarizability of dibenzothiophene was determinated to be 2.358 × 10−23 esu from the extrapolation of the dispersion curve to zero frequency. Theoretical calculations were performed with fully C2V optimized geometries at both the HF/6‐31G** and HF/6‐31 + G(d,p) levels of theory, and we present comparisons with the crystal structure of dibenzothiophene and HF/6‐31G** geometry of benzothiophene previously reported. We calculated the dipole polarizability by using the coupled perturbed Hartree–Fock analytical method, with both the STO/6‐31 + G(d,p) and STO/6‐31 + G(3d,3p) basis sets. We investigated the effects of exchange and electron correlation on these properties by using the BLYP and B3LYP hybrid approaches. The B3LYP/6‐31 + G(3d,3p) average polarizability value of dibenzothiophene is 2.425 × 10−23 esu, which differs from the experimental static value by 3%. Copyright © 2001 John Wiley & Sons, Ltd.
Magnetic polyglycidylmethacrylate microspheres by dispersion polymerization
Authors: Horák Daniel 
Published: August 2002

AbstractComposite polyglycidylmethacrylate [poly(GMA)] spherical microparticles capable of responding to magnetic fields were prepared by dispersion polymerization of GMA in the presence of iron oxides. The polymerization reaction was carried out in aqueous alcoholic media (methanol, ethanol, propan‐1‐ol, and butan‐1‐ol) using poly‐(N‐vinylpyrrolidone) and 2,2′‐azobisisobutyronitrile as a steric stabilizer and initiator, respectively. Quaternary ammonium salt (Aliquat 336) acting as an electrostatic costabilizer favorably affected dispersity. The solubility parameter of the reaction mixture determined the size of the resulting microspheres. In addition to the particle size distribution, the addition of iron oxide to the polymerization medium also caused a shift of the particle size to higher values. The results show that poly(GMA) particles contained up to 25 wt % iron oxide. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3707–3715, 2001
Atom transfer radical polymerization of n‐butyl acrylate from silica nanoparticles
Authors: Carrot G. , Diamanti S. , Manuszak M. , Charleux B. , Vairon J.‐P. 
Published: August 2002

AbstractThis article reports the synthesis of atom transfer radical polymerization (ATRP) of active initiators from well‐defined silica nanoparticles and the use of these ATRP initiators in the grafting of poly(n‐butyl acrylate) from the silica particle surface. ATRP does not require difficult synthetic conditions, and the process can be carried out in standard solvents in which the nanoparticles are suspended. This “grafting from” method ensures the covalent binding of all polymer chains to the nanoparticles because polymerization is initiated from moieties previously bound to the surface. Model reactions were first carried out to account for possible polymerization in diluted conditions as it was required to ensure the suspension stability. The use of n‐butyl acrylate as the monomer permits one to obtain nanocomposites with a hard core and a soft shell where film formation is facilitated. Characterization of the polymer‐grafted silica was done from NMR and Fourier transform infrared spectroscopies, dynamic light scattering, and DSC. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4294–4301, 2001
Synthesis of a soluble vinyl‐type polynorbornene with a half‐titanocene/methylaluminoxane catalyst
Authors: Wu Qing , Lu Yingying 
Published: August 2002

AbstractNorbornene polymerization was performed with monocyclopentadienyltitanium tribenzyloxide activated with methylaluminoxane (MAO). The catalyst afforded a pure vinyl‐type polymer at temperatures below 80 °C and at appropriate MAO concentrations. However, at higher temperatures or high MAO concentrations, a portion of the titanium species was pyrolyzed to form an alkylidene compound that catalyzed the ring‐opening metathesis polymerization of norbornene. As a result, both vinyl‐type and ring‐opening polymers were produced under the reaction conditions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1421–1425, 2002
Design of polyethers, thioethers, and amines with pendent iron moieties
Authors: Abd‐El‐Aziz A. S. , Todd E. K. , Ma G. Z. 
Published: August 2002

AbstractSoluble organoiron polyethers, thioethers, and amines were synthesized via nucleophilic aromatic substitution reactions. The synthesis of these classes of organometallic polymers involved either the reaction of cyclopentadienyliron complexes of dichloroarenes with various oxygen and sulfur dinucleophiles or the reaction of ether‐ or amine‐containing diiron complexes with dithiols. Polymerization reactions with the diiron complexes gave rise to organoiron polymers with alternating ether/thioether or amine/thioether bridges. Removal of the iron moieties from the backbone of these polymers allowed for the production of the corresponding organic materials. Furthermore, the organometallic polymers had much higher solubilities than their organic analogues. Thermogravimetric analysis of the organoiron polymers indicated that the polymers lost their metallic moieties at approximately 200 °C, whereas degradation of the polymer backbones occurred around 500 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1216–1231, 2001
Solvent effect on the free‐radical copolymerization of 2‐hydroxyethyl methacrylate with t‐butyl acrylate
Authors: Fernández‐Monreal Carmen , Martínez Gerardo , Sánchez‐Chaves Manuel , López Madruga Enrique 
Published: August 2002

AbstractThe free‐radical copolymerization of 2‐hydroxyethyl methacrylate with t‐butyl acrylate was carried out at 50 °C in bulk and in 3 mol · L−1 1,4‐dioxane and N,N′‐dimethylformamide solutions. Differences between the apparent reactivity ratios determined in this work indicated a noticeable solvent effect. This is explained with a qualitative bootstrap effect. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2043–2048, 2001
Rheological studies on the phase separation of hydroxypropylcellulose solution systems
Authors: Fujii Syuji , Sasaki Naoki , Nakata Mitsuo 
Published: August 2002

AbstractPhase behavior of hydroxypropylcellulose (HPC) in a mixed solvent of glycerol and water was investigated by two different rheological methods: rheooptical birefringence measurement in an elongational flow field and viscometric measurement in a shear flow field. The association process of the HPC chain during phase separation observed by the elongational flow birefringence method was also investigated by the shear viscometric method. The temperature dependence of chain rigidity was determined by measuring the intrinsic viscosity, and change in the conformation was investigated by observing elongational flow birefringence over the temperature range from the one‐phase to inside a phase boundary. The results focus on the molecular process of phase separation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1976–1986, 2001
Cavitation criterion for rubber materials: A review of void‐growth models
Authors: Fond C. 
Published: August 2002

AbstractThe principal criteria used to predict cavitation in rubber materials are reviewed, and experimental evidence is recalled for three different configurations: in the bulk, in the vicinity of a rigid particle, and in small rubber particles embedded in a rigid polymer matrix. Two major classes of cavitation criteria are defined, those based on an elastic instability (i.e., related to a stress state and finite strains) and those based on the energy balance (i.e., involving surface energies). The different criteria, in which various hyperelastic behavior laws are considered, are compared in numerical applications, and the tendencies are derived. The particular case of accounting for the surface tension of the rubber, a parameter common to the stress state and the energy balance, is treated in detail. It appears that the understanding of the genesis of a microcavity in a rubber material, when no pre‐existing flaw is assumed, still constitutes a difficulty for the analysis of mechanical damage in polymers containing a rubber phase. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2081–2096, 2001
Small‐angle X‐ray scattering and polymer melting: A model study
Authors: Crist Buckley 
Published: August 2002

AbstractSmall‐angle X‐ray scattering (SAXS) gives information on lamellar stacks in semicrystalline polymers. SAXS experiments have been used to follow the melting transition that occurs over a temperature range of 10 °C or more. One common feature is the increase in the average period by 50–100% during the melting process, a change that is often attributed to sequential melting of crystals in the lamellar stack. A quantitative treatment shows that the scattering experiment indicates only the original period, not the average period that increases throughout sequential melting. With this model, I discuss the relation between structural parameters of the melting structure and quantities derived from the SAXS intensity, the correlation function, and the interface distribution function. Uncertainties persist in our understanding of polymer melting. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2454–2460, 2001
Météorisation des Blocs de Granite à la Surface des Pédiments dans le Nord du Yukon, Canada
Authors: Bjornson Jean , Lauriol Bernard 
Published: August 2002

AbstractThis article describes how tors calve granite boulders which are then distributed in three zones on the surrounding pediments. The boulders are broken down to granules, sand, silt and clay on the surface of the pediments. The study site is located on a rounded hill of the Old Crow batholith near the Yukon‐Alaska border. The methods and techniques used were grain size analysis, rock and sediment geochemistry and boulder fabric. Results show that boulders become smaller and less frequent on the pediment as distance from the tor increases. Weathering processes disaggregate the boulders before they reach the talwegs. Chronological evaluation suggests that 10s to 100s ka are necessary for weathering to reduce the boulders to fine particles. Copyright © 2001 John Wiley & Sons, Ltd.
Cold‐climate origin of the enclosed depressions and wetlands (‘spungs’) of the Pine Barrens, southern New Jersey, USA
Authors: French Hugh M. , Demitroff Mark 
Published: August 2002

AbstractThe ‘frost‐thaw’ or thermokarst‐lake‐basin hypothesis, first invoked by P. E. Wolfe in 1953 to explain the enclosed depressions and shallow basins (‘spungs’) of southern New Jersey, is re‐examined. The most probable explanation is that they formed in late Wisconsinan times as deflation hollows, or ‘blowouts’, when strong katabatic winds flowed southwards from the continental ice margin across the sparsely vegetated, tundra terrain of the Pine Barrens. Wedge structures and cryoturbation phenomena suggest the existence of either permafrost or deep seasonal frost, and imply mean annual air temperatures of between −0.5 °C and −6 °C. When the groundwater table rose in late‐glacial times, the hollows became ponds or wetlands. These were utilized as early as 12,000 years ago by palaeoindian and early archaic cultures as hunting camp sites. Today, many of these wetlands are drying up as the regional water table falls in response to increased water usage from agriculture and urbanization. Copyright © 2001 John Wiley & Sons, Ltd.
Pharmacologically induced relaxation of tracheal smooth muscle is increased in hyperoxia‐exposed 15‐day‐old rats
Authors: Fayon Michael John , Denis Delphine , Molimard Mathieu , Berger Patrick , Choukroun Marie Luce , Demarquez Jean Louis , Marthan Roger , Clevel Huguette , Lachaud Jean Luc , Martinez Béatrice , Téchoueyres Pierre 
Published: August 2002

AbstractHyperoxia increases maximum airway contractility in newborn guinea pigs and immature rats. Studies examining the mechanisms of hyperoxia‐induced airway hyperresponsiveness have focused on contractile mechanisms, although excessive airway narrowing could be due to impaired relaxation. Our objective was to determine the effects of hyperoxia on airway structure and relaxing properties in juvenile rats exposed to an inspired fraction of oxygen (FiO2) of 0.5 within 24 hr of birth for 15 days, compared to a control group of air‐exposed rats. We studied the 1) tracheal smooth muscle surface area; and 2) in vitro relaxation in precontracted (carbachol, 1.10−3 M) isolated tracheal rings to increasing cumulative concentrations (10−8 to 10−4 M) of salbutamol.There was no significant difference in the amount of smooth muscle between the hyperoxia and air‐exposed groups. Maximal relaxation of the isolated trachea to salbutamol was greater in the hyperoxia group than in the air‐exposed group when normalized to smooth muscle surface area (−12.69 ± 3.51 g/mm2 vs. − 8.49 ± 1.67 g/mm2; P (MANOVA) < 0.05) or expressed as maximal relaxation induced by 10−3 M theophylline (61% vs. 28%; P < 0.05).In conclusion, salbutamol‐induced relaxation is enhanced (and not impaired) in newborn rats exposed to prolonged moderate hyperoxia. Pediatr Pulmonol. 2002; 33:124–129. © 2002 Wiley‐Liss, Inc.