bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of maleic acid and itaconic acid studied by FT‐Raman spectroscopy
Authors: Yang Charles Q. , Gu Xiaohong 
Published: August 2002

AbstractIn this research, we used a new redox free radical initiation system consisting of potassium persulfate (K2S2O8) and sodium hypophosphite (NaH2PO2). In the presence of NaH2PO2, the thermal decomposition of K2S2O8 is accelerated, and the temperature required for the formation of free radical is reduced. We polymerized maleic acid (MA) using the K2S2O8/NaH2PO2 initiation system in an aqueous solution, and monitored the polymerization process with FT‐Raman spectroscopy. The Raman spectroscopy data indicate the formation of a saturated carboxylic acid with the disappearance of the characteristic bands of MA as the thermal decomposition of K2S2O8 progresses, thus indicating the formation of poly(maleic acid) (PMA). We also found that itaconic acid (IA) polymerizes in the presence of the new initiation system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 223–228, 2001
Hollow fiber formation using Lewis acid : Base complex in the polymer solution
Authors: Pereira C. C. , Souza J. N. M. , Nobrega R. , Borges C. P. 
Published: August 2002

AbstractIn the present work, hollow fiber formation was investigated by using Lewis acid : base complexes in the polymer solution. The studied systems consisted of poly(ether sulfone); N‐methyl‐2‐pyrrolidone (NMP) as solvent and Lewis base, and acetic, propionic, n‐caproic, and adipic acids as additives and Lewis acids. Bore liquid was formed by water/NMP solutions, as well as vaseline; whereas water was used as external precipitation bath. The spinneret and precipitation bath distance (i.e., air gap) also varied. The membranes were characterized by scanning electron microscopy and pure gas permeation tests. The influence of the complex dissociation rate was observed mainly when a reduction to water inflow from the bore liquid to the polymer solution occurred, because in this case, dissociation rate was inhibited. Therefore, stability was favored in the sublayer for a longer period, allowing macrovoid formation. These results are also evidenced by the permeability coefficients, which increased as fast as the polymer solution reaches water (i.e., the kinetics of precipitation was accelerated). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 908–917, 2001
New synthetic method for soluble starlike C60‐bonding polymers
Authors: He Ji‐Dong , Wang Juan , Li Si‐Dong , Cheung Man Ken 
Published: August 2002

AbstractNovel starlike C60‐bonding polymers were synthesized by using the iniferter technique. The fullerene C60 with pendent N,N‐diethyldithiocarbamate groups (C60–SR) was used as polyfunctional photoiniferter. The effects of UV‐irradiation time and ambient temperature on the molecular weight of polymer were investigated. The photopolymerization with C60–SR proceeded via a living‐radical mechanism, and gave soluble polyfunctional polymers (photoiniferters). Multiple polymer arms were attached to the C60 core and the polymers obtained by C60–SR could also be used as excellent crosslinking agents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1286–1290, 2001
The forced gas sweeping process for semibatch melt polycondensation of poly(ethylene terephthalate)
Authors: Woo Boogon , Choi Kyu Yong , Goranov Konstantin 
Published: August 2002

AbstractThe experimental and modeling studies are presented on the melt polycondensation of poly(ethylene terephthalate) by a gas sweeping process. In this process, low molecular weight prepolymer is polymerized to a higher molecular weight polymer in a molten state at ambient pressure as ethylene glycol is removed by nitrogen gas bubbles injected directly to the polymer melt through a metal tube. In the temperature range of 260–280°C, the rate of polymerization by the gas sweeping process is quite comparable to that of conventional high vacuum process. The effects of nitrogen gas flow rate and reaction temperature on polymerization rate and polymer molecular weight were investigated. Polymer molecular weight increases with an increase in gas flow rate up to certain limits. A dynamic mass transfer–reaction model has been developed, and the agreement between experimental data and model simulations was quite satisfactory. The effect of ethylene glycol bubble nucleation on the polymerization has also been investigated. It was observed that the presence of nucleated ethylene glycol bubbles induced by the bulk motion of polymer melt has negligible impact on the polymerization rate and polymer molecular weight. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1388–1400, 2001
Cysteic acid is the chemical mediator of automotive clearcoat damage promoted by dragonfly eggs
Authors: Stevani Cassius V. , Liria Cleber W. , Miranda M. Terêsa M. , Bechara Etelvino J. H. 
Published: August 2002

AbstractThe damage caused by dragonfly eggs on automotive clearcoats exposed to sunlight occurs by a chemical mechanism similar to that caused by acid rain. Cysteine and cystine residues present in dragonfly eggs are oxidized during the egg hardening process, which releases hydrogen peroxide, to a cysteic acid derivative, a strong acid capable to catalyze the hydrolysis of acrylo/melamine clearcoat polymer. Cysteic acid was indeed identified and quantified by ion‐exchange HPLC in dragonfly egg extracts submitted to oxidation by H2O2 followed by acid digestion. Moreover, H2O2 concentration, temperature, and exposure time profiles of cysteic acid formation as well as an apparent activation energy for cysteine (in dragonfly eggs) oxidation to cysteic acid by H2O2 (32 ± 2 kJ/mol) were determined. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1549–1554, 2001
Unsaturated polyester resin modified with poly(organosiloxanes). II. Acoustic emission study on glass‐fiber‐reinforced resin
Authors: Rosa Valéria Maria , Karger‐Kocsis Jozsef , Felisberti Maria Isabel 
Published: August 2002

AbstractThis work aims to study the adhesion of an isophthalic acid based unsaturated polyester resin chemically modified by grafting copolymerization of a poly(organosiloxane) to the glass fiber. The failure mode of the single‐edge notched tensile specimen, cut from pressed plates containing 50 wt % of nontreated and silane‐treated milled glass fiber, was studied by acoustic emission (AE) technique. It was found that the aforementioned resin modification enhanced the adhesion between the fiber and the resin. This was suggested by a shift in the AE amplitude and energy toward higher values. On the other hand, the matrix modification had no significant effect if glass fiber with suitable unsaturated polyester resin (UP) sizing was incorporated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3280–3289, 2001
Formulation/property relationships in radiation‐cured poly(urethane methacrylate) pressure‐sensitive adhesives. II. Variation of the chain terminator component
Authors: Ansell C. W. G. , Masters S. J. , Millan E. J. 
Published: August 2002

AbstractThe synthesis of a series of radiation‐curable poly(urethane methacrylate) oligomers are reported, which, on exposure to electron‐beam irradiation, result in adhesive films with pressure‐sensitive properties. Variation of the chain terminator component of the formulation and the effect of this on adhesive properties were investigated. Adhesive systems utilizing Dowfax 9N6 nonylphenolethoxylate, 1‐(2‐hydroxyethyl)‐2‐pyrrolidinone, 2‐hydroxyethyl salicylate, or 4‐(2‐hydroxyethyl)morpholine as alternative chain terminators performed in a manner that may make them suitable for medical applications. Terminators with higher ethoxylation levels (Brij 35, 58) conferred high hydrophilicity on the resulting adhesives. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3321–3326, 2001
The potential of Cu(I)Cl/2,2′‐bipyridine catalysis in a triblock copolymer preparation by atom transfer radical polymerization
Authors: Masař Bohumil , Vlček Petr , Kříž Jaroslav 
Published: August 2002

AbstractThe ability of atom transfer radical polymerization (ATRP) in the sequential synthesis of triblock copolymers was examined using Cu(I)Cl/2,2′‐bipyridine catalysis at 110°C in toluene, starting from PMMA macroinitiators terminated with the C‐Br group. The PMMAs were prepared by living anionic or group transfer polymerization (GTP), followed by bromination of the respective active site with Br2 or N‐bromosuccinimide (NBS). The yield of the terminal bromination in the products of both living polymerizations was 60–64% at best, compared with the yield of the bromination of 1‐methoxy‐(1‐trimethylsilyloxy)prop‐1‐ene (a model of the GTP active site) with NBS, as found by 1H‐NMR. The PMMA macroinitiators prepared were utilized to start the sequential ATRP, finally affording PMMA‐b‐PBuA‐b‐PSt (Mn 69,100), PMMA‐b‐PSt‐b‐PBuA (Mn 21,300) and PMMA‐b‐PSt‐b‐PMMA (Mn 35,200), which have not yet been synthesized by ATRP. After the second block has been formed, the Br‐unterminated part of PMMA macroinitiator was removed by extraction or repeated precipitation. In the third (last) sequence polymerization, induction periods were observed. The first two triblock copolymers were free of precursors and have Mw/Mn values 1.5–1.6 (SEC). In the course of the last step of PMMA‐b‐PSt‐b‐PMMA synthesis, the content of the PMMA‐b‐PSt precursor slowly decreased with increasing MMA conversion. Still, at ≈90% MMA conversion, about 10–15% of the precursor remained in the product. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3514–3522, 2001
Preparation of polypropylene/acrylonitrile–styrene copolymer alloys by one‐step reactive blending
Authors: Xie Xu‐Ming , Liu Ya‐Yun , Guo Bao‐Hua , Feng Jun , Ishikawa Tatsuo , Morinaga Takashi 
Published: August 2002

AbstractThe compatibilization of polypropylene/acrylonitrile–styrene (PP/AS) blends through the addition of peroxide (DCP) was investigated in this study. The grafting reaction between PP and AS with the addition of peroxide occurred during the reactive‐blending process. The in situ‐formed grafting copolymers of PP‐g‐AS and AS‐g‐PP were then characterized by FTIR. The optimum concentration of the initiator, DCP, was 0.2 wt %, and the reaction temperature should be above 195°C. It was found that, when AS was the major component of the blends, the grafting of AS onto PP was the main process; conversely, when PP was the major component, PP was grafted onto AS. These results can be explained by the main‐chain scission of PP during the reactive‐blending process. With increase of the AS component, the total degree of grafting increased at first and then decreased after the composition of the blends reached 50/50. The maximum degree of grafting was found to be 6 wt % for the 50/50 PP/AS/DCP blend. PP was more degradable than was AS in the presence of peroxide at high temperatures. The MFR values of the PP/AS/DCP blends were slightly greater than were those of the simple PP/AS blends, which means that blending is an effective way to protect PP from degradation. SEM micrographs of the cross section of PP/AS/DCP showed a fine dispersion and a smaller domain size of the dispersed‐phase particles, implying that the in situ‐formed grafting copolymers act as a compatibilizer to reduce the interfacial tension between the PP and AS phases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1284–1290, 2001
Drying of heterogeneous hydrogels formed with various water contents: A photon transmission study
Authors: Kara Selim , Pekcan Önder 
Published: August 2002

AbstractDrying of acrylamide (AAm) gels was monitored by using a photon transmission technique. These hydrogels are formed from AAm and N,N′‐methylenebis(acrylamide) (Bis) with various water contents by the free‐radical crosslinking copolymerization (FCC). The transmitted light intensity, Itr, increased continuously as AAm gels were dried. The increase in Itr was attributed to the decrease in the scattered light intensity, Isc, which might be originated from the contrast between frozen blob clusters and holes in the drying gel. A decrease in Isc was modeled by using Rayleigh's equation where drying times with various exponents were found to be proportional to the size of the holes. It was observed that the radius of holes, ξc, decreased in various powers of the drying time depending on water content used during FCC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1944–1951, 2001
Carbazole‐based electroluminescent devices obtained by vacuum evaporation
Authors: D'Almeida K. , Bernède J. C. , Ragot F. , Godoy A. , Diaz F. R. , Lefrant S. 
Published: August 2002

AbstractTransparent conductive oxide (SnO2)/organic layers/aluminum thin film sandwich structures were obtained by vacuum evaporation. The organic component was either a thin carbazole film or a bilayer. In that case, the carbazole film was deposited onto a thin insulating polymer film. The polymer used was the poly(tetrabromo‐p‐phenyleneselenide) (PBrPDSe). Photoluminescence measurements have shown that the carbazole thin films emit blue light. (I‐V) measurements have shown that the structures exhibit diode characteristics. The forward direction is obtained when the transparent conductive oxide (TCO) is positively biased. However, the reproducibility of the results obtained with a single carbazole layer is poor. It appears that the stability of the sample is improved when a thin PBrPDSe film (40 nm) is introduced between the carbazole and the SnO2. The polymer film avoids the short circuit effect. In that case, the turn‐on voltage of the diode is about 3 V, when the thickness of the carbazole film is around 250 nm and the electroluminescence appears at a voltage of about 5 V. It is shown that the thermionic effect cannot be used to explain the I‐V characteristics, which are interpreted with the help of the Fowler–Nordheim tunnel effect. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2042–2055, 2001
Amphiphilic copolymers of glycidol with nonpolar epoxide comonomers
Authors: Royappa A. Timothy , Dalal Naresh , Giese Matthew W. 
Published: August 2002

AbstractTo explore the industrially used copolymerization of glycidol with other epoxide species, a series of copolymers of glycidol with various comonomers (epichlorohydrin, isopropyl glycidyl ether, 1,2‐epoxybutane, propylene oxide, and glycidyl phenyl ether) has been synthesized by cationic ring‐opening polymerization in dichloromethane, using boron trifluoride diethyl etherate as the initiator. The facile synthesis proceeded at room temperature under ordinary atmosphere. The air‐ and temperature‐stable products—mostly clear, colorless, viscous liquids—are proposed to consist of a hyperbranched polyglycidol core (incorporating varying fractions of comonomer) with arms made from comonomer‐derived repeat units. These copolymers had low molecular weights and rather broad molecular weight distributions. There was wide variation in the polarity of these copolymers, depending on the comonomer used, resulting in materials that were soluble in solvents ranging from benzene to water. The glass‐transition temperatures observed for these copolymers also varied widely, ranging from −56 to 1°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2290–2299, 2001
Cure kinetics of diglycidylether of bisphenol A– ethylenediamine revisited using a mechanistic model
Authors: Riccardi C. C. , Fraga F. , Dupuy J. , Williams R. J. J. 
Published: August 2002

AbstractThe polymerization kinetics of the reaction between diglycidylether of bisphenol A (DGEBA) and ethylenediamine (EDA) was analyzed, using dynamic scanning calorimetry, in both isothermal and programmed heating‐rate modes. A simple mechanistic model, consisting of an equilibrium reaction generating an epoxy–hydroxyl complex, and including two possible mechanisms for the consumption of amine hydrogens [(1) with free epoxy groups, (2) with the epoxy–hydroxyl complex], provided a reasonable fitting of the whole set of experimental results. It was found that the equilibrium constant decreased with temperature, making less important the reaction mechanism involving the epoxy–hydroxyl complex. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2319–2325, 2001
Kinetic evaluation of an oligomeric amidation reaction
Authors: Khan Abdul Rehman , Al‐Roomi Yousef M. , Mathew Johnson , Sari Majed 
Published: August 2002

AbstractHomopoly(amides) similar to those of liquid crystalline poly(oxybenzoate) were prepared by acidolysis of the monomer p‐acetamidobenzoic acid. The kinetics of catalyzed and uncatalyzed acidolysis of the 4‐acetamidobenzoic acid were investigated at 265, 275, and 285°C. A second‐order rate model, which can analyze kinetic parameters of two different kinetic regimes, was used to interpret the experimental data for 18 different experimental sets. It is observed that the correlation coefficient between observed and calculated values range between 0.98 and 0.99, confirming the validity of the stated model. The nature of the kinetic behavior in the two regimes was found to be independent of both catalyst type and concentration. In effect second‐order rate law adequately describes the entire kinetic behavior of this system. The Arrhenius constants and activation energy parameters for this system have been reported. Differential scanning calorimetry (DSC) results of the oligomers indicate that the homopoly(amides) melt around 360°C with degradation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2534–2543, 2001
Application of differential scanning calorimetry and differential thermogravimetry techniques to determine the ratio of blend components in reactive chlorinated elastomer blends
Authors: Tripathy A. R. , Patra P. K. , Sinha J. K. , Banerji M. S. 
Published: August 2002

AbstractQuantitative and qualitative analyses of chlorine‐containing elastomer blends, like neoprene rubber/chlorosulfonated polyethylene and neoprene rubber/nitrile–polyvinyl chloride, with carbon black and other fillers, are complex and confusing because the blends contain the same carbonchlorine moiety. Various interfering phenomena by fillers, co‐curing by the common ingredients, and uncertainty in functional group analysis make the determination of the ratio of component elastomers in chlorine‐containing elastomer blends very difficult or sometimes almost impossible by Fourier transform infrared and thermogravimetric analysis techniques. However, differential scanning calorimetry (DSC) and supportive differential thermogravimetry (DTG) are very useful techniques to assess such complex materials. Enough flexibility associated with specific heat (from DSC) and response zone (from DTG) can avoid the interfering effects. The DSC–DTG technique thus can be an effective tool to determine the ratio of component polymers in chlorine‐containing elastomer blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 937–948, 2002
Controlled radical polymerization catalyzed by CuCl/BDE complex in water medium. II. Polymerization of methyl methacrylate and formation of PMMA with bimodal molecular weight distribution
Authors: Wan Xiaolong , Liu Yanfei , Ying Shengkang 
Published: August 2002

AbstractThe emulsion polymerization of MMA was explored for the BDE/CuCl coordinated catalyst. The Mn of PMMA linearly increased both with increasing the monomer conversion and the proceeding polymerization time, which means that the MMA polymerized in “living”/controlled characters with zero order kinetics under BDE/CuCl‐catalyzed emulsion conditions. The apparent polymerization rate constants of MMA were k = 0.765 mol/min, k = 0.760 mol/min at 80°C, while k = 0.228 mol/min at 50°C, respectively. Slight differences of polymerization results were obtained when emulsifier lauryl phosphate (ADP) and Polyoxyethylene nonyl phenyl ether (OP‐10) were adapted in the polymerization. Based on the “coordinated radical cage” mechanism proposed particularly to the BDE/CuCl catalyzed polymerization, reversible equilibrium between common free radical and the coordinated “living” species should exist in this system. Increasing the amount of catalyst must affect the fast equilibrium between those two species, thus, also affecting the relative content in the emulsion circumstance. Therefore, PMMA, with bimodal molecular weight distribution, was achieved through this approach. The formation of PMMA with bimodal distribution was affected by concentration of catalyst and polymerization temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3076–3081, 2002; DOI 10.1002/app.2336
Active and passive remote sensors as a new technology for coastal and lagoon monitoring
Authors: Alberotanza Luigi 
Published: August 2002

Abstract1. Important environmental problems of coastal and lagoon areas have stimulated interest in scientific research. Innovative technologies can provide good tools for observing phenomena and measuring parameters.2. The short overviews given in this article refer to the results obtained using active remote sensors and passive remote sensors in practical applications to support monitoring and research activities.3. Active sensors such as FLIDAR‐3 (Fluorescence Light Detection and Ranging) (optical), tomography (acoustical), and CODAR (Coastal Ocean Dynamics Applications Radar) (radio) emit their own electromagnetic energy to the investigated surface and sense the reflected energy from the surface; while the passive sensors, such as MIVIS (Multispectral Infrared and Visible Imaging Radiometer), NOAA (National Oceanographic and Atmospheric Agency)/AVHRR (Advanced Very High Resolution Radiometer) and Landsat/TM, do not emit energy but measure energy reflected/emitted to the sensor from the investigated surface. Copyright © 2001 John Wiley & Sons, Ltd.
Morphology‐based systematics (MBS) and problems with fossil hominoid and hominid systematics
Authors: Sarmiento Esteban E. , Stiner Eric , Mowbray Ken 
Published: August 2002

AbstractThe generalized/primitive nature of the hominoid dentition and often fragmentary nature of fossils, coupled with enthusiastic optimism for making revolutionary finds, has wreaked havoc with recognition of early human ancestors and reconstruction of fossil hominoid phylogeny. As such, the history of paleoanthropology is one of repeated misidentification of fossil ancestors and of occasional fraud. Although this history has led many workers to lose confidence in morphology based systematics (MBS), past and present misidentifications are actually due to a disregard of systematic methodology. Systematics depends on the continuity of life and gains its objectivity largely from the order alpha taxonomy imposes on morphologic discontinuities in closely related taxa (i.e., species and genera). Transformation of characters fixed in species into character complexes, as manifested in taxa nested at different levels of relationship, form the foundation for higher‐level taxonomy and for phylogeny. Because in most cases, hominoid fossils are unable to provide the data needed to resolve alpha taxonomy, classification and phylogeny of fossil taxa must be guided by analogies to living taxa. Hominid and hominoid fossil taxonomy and phylogeny, however, has been based largely on preevolutionary notions and on misinterpretations of the polarity of assumed diagnostic characters. More often than not, fossils lack resolution for the taxonomic level or rank they are assigned to and taxa are erected without appropriate analogies to living forms. As such, phylogenies based on these classifications are unlikely to be correct. More in‐depth anatomical studies that are in accordance with systematic methodology are likely to hold the key to correctly classifying fossils and unraveling hominoid and hominid phylogeny. Anat Rec (New Anat) 269:50–66, 2002. © 2002 Wiley‐Liss, Inc.