bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal stability studies of transparent conducting polyaniline composite films on their conductivity and optical spectra
Authors: Byun Sung Weon , Im Sung Soon 
Published: April 2003

AbstractThe thermal stability of highly transparent and conducting polyaniline–Nylon 6 (PAn‐N) composites films doped with various protonic acids such as hydrochloric acid (HCI), benzenesulfonic acid (BSA), sulfosalicylic acid (SSA), and p‐toluenesulfonic acid (TSA) was investigated at different elevated temperatures under air atmosphere. Two different degradation kinetic processes of electrical conductivity were found depending on the species of protonic acids. The conductivity degradation of PAn‐N composite films doped with SSA and TSA were found to obey first‐order reaction kinetics, while that of the other dopants was found to follow multiorder kinetics. Spectroscopic studies revealed that the thermal de‐doping process of doped composite films, which reversed the doping process, took place without major structural modifications of the polyaniline in the composite system but was not completely reversible. From the differential scanning calorimetry (DSC) study, the crystal structure of the composite films was found to be affected by the formation of polyaniline in matrix polymer and depended on the types of dopant species. © 1995 John Wiley & Sons, Inc.
Polymer‐anchored metal complexes. III. Preparation, structural, thermal stability, dielectric, and conductivity characterization of polycondensates from Cu(II)–1, 10‐phenanthroline and trimellitic anhydride/pryromellitic dianhydride
Authors: Biswas Mukul , Mukherjee Amit 
Published: April 2003

AbstractTrimellitic anhydride and pyromellitic dianhydride have been polycondensed with Cu(II)–phenanthroline complex as a comonomer in the presence of anhydrous ZnCl2 under selective conditions. Elemental diffuse reflectance and infrared spectroscopic and X‐ray diffraction (XRD) analysis data of these polymers have been correlated with the tentative structure Proposed for these polycondensates. Thermal stability and dielectric and conductivity characteristics of these polycondensates have been evaluated to understand the effect of the ligand and the anhydride moieties on these properties. Unlike the polymer‐anchored 3d‐metal complexes, these polycondensates fail to initiate the cationic polymerization of N‐vinylcarbazole. © 1995 John Wiley & Sons, Inc.
Effects of processing parameters on material properties of mechanically processed polyamide
Authors: Pan J. , Shaw W. J. D. 
Published: April 2003

AbstractA semicrystalline polyamide polymer was processed using a new technique known as mechanical alloying. The material processed by this technique was first introduced into a high‐energy ball mill and ground over long periods of time, resulting in the production of extremely fine powders. These powders were subsequently consolidated well below the materials' melting‐point temperature. The effect of processing parameters including mechanical milling time, consolidation temperature, and the length of consolidation time were studied fairly extensively. The investigation shows that polyamide powders are continually refined with increasing mechanical milling time and the resulting materials have improved mechanical properties. The influence of both consolidation temperature and the length of consolidation time on material properties indicate that materials with higher density, crystallinity, hardness, strength, and ductility are produced when consolidated using higher temperatures and longer times. © 1995 John Wiley & Sons, Inc.
Real‐time monitoring of diffusion in polymer films using fluorescent tracer
Authors: Krongauz V. V. , Mooney W. F. , Palmer J. W. , Patricia J. J. 
Published: April 2003

AbstractA method for real‐time nondestructive monitoring of small molecules diffusion in polymeric films was developed. The method was based on detection of a fluorescent tracer eluting from the investigated polymer film into the solution in which this film was immersed. The kinetics of the tracer elution, monitored by the increase in solution fluorescence intensity, was used to deduce tracer diffusivity in polymer film. The data were treated using a straightforward mathematical model, describing diffusion from an infinite plane of a certain thickness immersed into a finite solvent bath. Fluorescent 7‐diethylamino‐4‐methyl coumarin was used as a tracer. The diffusion of this tracer within plasticized poly(methyl methacrylate) and styrene‐isoprene‐styrene block copolymer matrices was monitored. The diffusion coefficients equal to 2 × 10−9 cm2/s and 1 × 10−9 cm2/s, respectively, were obtained. © 1995 John Wiley & Sons, Inc.
Grafting maleic anhydride and comonomers onto polyethylene
Authors: Samay Geza , Nagy Tibor , White James L. 
Published: April 2003

AbstractGrafting dicarboxylic anhydrides onto polyolefins has great practical importance. The process of grafting maleic anhydride onto high‐density polyethylene in the presence of various comonomers in an intermeshing corotating twin‐screw extruders was studied. Three types of comonomers were investigated: (i) vinyl monomers, including styrene and methacrylic acid; (ii) esters of dicarboxylic acids forming succinic groups after grafting, such as fumaric acid; and (iii) esters of fumaric and maleic acid and ethylenically unsaturated cyclic dicarboxylic anhydrides, such as Diels–Alder adducts of maleic anhydride; and (iv) dienes and dodecenyl succinic anhydride. © 1995 John Wiley & Sons, Inc.
Gas permeation property of polyaniline films
Authors: Hachisuka Hisao , Ohara Tomomi , Ikeda Ken‐Ichi , Matsumoto Kenji 
Published: April 2003

AbstractWe examined the influence of polyaniline (PAn)'s unit sequence and doping with low molecular weight dopants or polymer dopants on permeation property. It was found that CO2 permeability was increased by the formation of a quinonediimine unit in PAn with the oxidation. CO2 sorption amount of PAn was decreased by oxidation. The increase of CO2 permeability with oxidation, therefore, resulted from the increase of diffusivity, which was attributable to morphological variation by the increase of a quinonediimine unit. The permselectivity of PAn films was found to be remarkably improved by doping. In particular, the selectivity value of the PAn film doped with polyvinyl sulphonic acid as a polymer dopant went up to over 2,000. This remarkable increase of selectivity was found to result in the increase of selectivity, depending on diffusivity. It was also found that the permselectivity of the PAn film doped by polymer dopants was surpassed, as compared with that doped by low molecular dopants. © 1995 John Wiley & Sons, Inc.
Polarity measurements in block copolymers (polyurethaneimides) and correlation with their pervaporation features
Authors: Jonquières Anne , Roizard Denis , Cuny Joël , Vicherat André , Lochon Pierre 
Published: April 2003

AbstractEtOH/ETBE azeotropic mixture was separated by pervaporation through films of polyurethaneimides (PUI), i. e., alternating block copolymers varying in their structure only by their oligomeric soft blocks. Pervaporation performances strongly depend on the flexible segments: fluxes on the molecular weight and selectivity towards ethanol on the chemical structure in the decreasing order: PEG, PCL, PCD, PTMG, PPG. In order to correlate selectivity with segment polarity, a new solvatochromic polarity probe that was well soluble in PUI was synthesized. Using 13 solvents covering a wide polarity range, Vis λmax of the photochromic indicator open form was linearly correlated with the ET(30) polarity scale. By illumination of the dissolved dye, PUI polarity was investigated in relation to soft segment nature and size. The very high PUI polarity values and their splitting for highest size segments were assigned to preferential probe solvation by interblock urethane junctions combined with phase segregation. Polarity values consistent with the chemical structure of the flexible segments were provided by similar measurements on suitably end‐capped precursors of these segments and were then linearly correlated with the related PUI pervaporation selectivity. © 1995 John Wiley & Sons, Inc.
Effects of polymer matrix and salt concentration on the ionic conductivity of plasticized polymer electrolytes
Authors: Whang Wha‐Tzong , Lu Chou‐Ling 
Published: April 2003

AbstractTwo polar polymers with different dielectric constants, poly(vinylidene fluoride) (PVDF) and poly(ethylene oxide) (PEO), were each blended with a chlorine‐terminated poly(ethylene ether) (PEC) and one of the two salts, LiBF4 and LiCF3CO2, to form PEC plasticized polymer electrolytes. The room‐temperature ionic conductivity of the PEC plasticized polymer electrolytes reached a value as high as 10−4 S/cm. The room‐temperature ionic conductivity of the PVDF‐based polymer electrolytes displayed a stronger dependence on the PEC content than did the PEO‐based polymer electrolytes. In PVDF/PEC/LiBF4 polymer electrolytes, the dynamic ionic conductivity was less dependent on temperature and more dependent on the PEC content than it was in PEO/PEC/LiBF4 polymer electrolytes. The highly plasticized PVDF‐based polymer electrolyte film with a PEC content greater than CF4 (CF4 defined as the molar ratio of the repeat units of PEC to those of PVDF equal to 4) was self‐supported and nonsticky, while the corresponding PEO‐based polymer electrolyte film was sticky. In these highly plasticized PVDF‐based polymer electrolytes, the curves of the room‐temperature ionic conductivity vs. the salt concentration were convex because the number of carrier ions and the chain rigidity both increased with increase of the salt content. The maximum ionic conductivity at 30°C was independent of the PEC content, but it depended on the anion species of the lithium salts in these highly plasticized polymer electrolytes. © 1995 John Wiley & Sons, Inc.
Mechanism of polyphenolic tannin resin hardening by hexamethylenetetramine: CP–MAS 13C‐NMR
Authors: Pizzi A. , Tekely P. 
Published: April 2003

AbstractPolyflavonoid tannins have been shown by 13C‐NMR to react with hexamethylenetetramine (hexamine) at considerably higher rates than with phenol with the formation of both benzylamine and methylene crosslinks to form hardened resins. Predominantly prodelphinidintype tannins appear to present a much higher proportion of benzylamine bridges than of methylene bridges, while in procyanidin‐type tannins the proportion of the two types of crosslinks appear to be comparable. The greater the nucleophilicity of the flavonoid tannin A‐rings, the greater is the proportion of benzylamine bridges which appear to form. At parity of the type of tannins, the faster the reaction with hexamine, the higher the proportion of benzylamines which appear to form. © 1995 John Wiley & Sons, Inc.
Nonaqueous chromatography of biopolymers by means of their poly(ethylene glycol)‐mediated solubilization in alcohols
Authors: Bromberg Lev 
Published: April 2003

AbstractFreeze‐drying of aqueous solutions of biopolymers and excess poly(ethylene glycol)s leads to formation of hydrophobic complex. Complexation with PEG increases solubility of low molecular weight DNA, RNA, and several proteins in neat ethanol and methanol. Solubilized nucleic acids can be fractionated, and proteins separated by nonaqueous reversed phase HPLC. © 1995 John Wiley & Sons, Inc.
Preparation and solution properties of ionomer originated from styrene–coumarin copolymer
Authors: Chen Yun , Chen Yung‐Hsiu 
Published: April 2003

AbstractA novel ionomer was successfully prepared by lactone ring opening of stryrene–coumarin copolymer, containing 9.28 mol % of coumarin, with aqueous NaOH solution. Its solution properties in methanol, including reduced viscosity and surface tension, were investigated as a function of temperature, concentration, and pH value. The reduced viscosities of the ionomer solution decrease smoothly with increasing temperature and concentration. Moreover, the viscosities of the ionomer solution (0.3 g/dL MeOH) are ca. twofold of the copolymer solution (0.3 g/dL THF) between 25 and 45°C. It increases from ca. 0.14 to 0.59 dL/g as pH value decreases from 10.6 to 6, then decreases slightly and reaches a constant value of 0.47 dL/g below pH 4.7. The surface tension of methanol solution decreases with increasing concentration and reaches an asymptotic value of 24.1 dyne/cm as the concentration is above 0.50 g/dL due to the surface‐active effects. These properties can be related to the balance between hydrogen bonding and charge–charge interactions that occur along the ionomer backbone. © 1995 John Wiley & Sons, Inc.
Colorimetric evaluation of thermooxidative degradation of nylon 6 fibers
Authors: Hamza A. A. , El‐Tonsy M. M. , Fouda I. M. , El‐Said A. M. 
Published: April 2003

AbstractNylon 6 fibers were annealed in air at 160°C for periods ranging from 1 to 10 h. Their spectral reflectance values were measured. Color parameters, including luminance factor, dominant wavelength, purity, and the color difference between annealed nylon 6 fiber samples and unheated ones were calculated. The observed variations in the colors of samples were assumed due to the thermal and oxidation degradations. The behavior of the color parameters with heating duration was compared with the general kinetic curve of thermooxidative degradation of polymers and the match between them is discussed. The color difference ΔE values is recommended for monitoring the thermooxidative degradation of nylon 6 fibers. © 1995 John Wiley & Sons, Inc.
Cure characterization of triglycidyl epoxy/aromatic amine systems
Authors: Padma A. , Rao R. M. V. G. K. , Subramaniam C. , Nagendrappa G. 
Published: April 2003

AbstractThe curing of triglycidyl para‐aminophenol (TGPAP) epoxy resin with three aromatic amine hardeners, diaminodiphenye sulphone (DDS), pyridinediamine (PDA), and toluenediamine (TDA), has been investigated. A series of iosthermal cures was conducted and analyzed by Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC). The chemical reactions occurring during cure were monitored at different temperatures by qualitative and quantitative estimation of different groups in the IR spectra, and the ratio of rate constants (k2/k1) were evaluated. Dynamic DSC analysis of TGPAP/TDA resulted in two exothermal peaks, indicating cure kinetics different from those of TGPAP/DDS and TGPAP/PDA systems, which gave a single exothermal peak. Various kinetic parameters such as total heat of reaction. ΔH′, activation energy Ea, Frequency factor z, and order of reaction n were evaluated for all the three systems. From the initial kick‐off temperatures and activation energy values it was concluded that the rate of curing followed the order TDA > PDA > DDS. The reaction conversions during cure, evaluated from IR analysis, were exactly the same as those obtained from DSC Borchardt–Daniels kinetics. Using this model, the plots of time vs. temperature for different conversions were constructed for all the three systems; on the basis of these, the cure cycles can be fixed. © 1995 John Wiley & Sons, Inc.
Gas transport properties of siloxane polyurethanes
Authors: Pegoraro Mario , Severini Febo , Gallo Raffaele , Zanderighi Luciano 
Published: April 2003

AbstractPolyurethanes (PUs) were synthesized from toluenediisocyanates (TDIs) and a polymeric diol having polydimethylsiloxane and polyoxyethylene blocks of the ABA type, ended with OH groups. Prepolymers, prepared in toluene solution using ratios [NCO]/[OH] ≥ 2, were crosslinked with triisopropanolamine (TIPA) (ratio [OH]/[NCO] = 1.1) (two‐step process). PUs were also obtained with a one‐step process using, contemporaneously, TDI, block copolymer, and, as crosslinking agent, TIPA or the glyceride of ε‐hydroxyhexanoic acid. Polydimethylsiloxane (PDMSO) was prepared as a reference material. The course of the reaction between block copolymer and TDI was studied by differential scanning calorimetry in the absence and presence of benzoyl chloride (BzCl). Without BzCl, with ratios [NCO]/[OH] > 2, uncontrolled crosslinking side reactions occur. The properties of the PU films obtained with the two methods were studied both for the density of crosslinking and for gas transport properties. The two‐step polymers are less crosslinked than the others and are characterized by higher diffusion coefficients and by higher permeability to gases. The permeability order is 10−9 (N cm3 cm−1 cm−1 cm Hg−1 s−1) for CH4, O2, CO, and N2 and is 10 times higher for CO2. The selectivity for the couple O2/N2 is higher than that obtained with PDMSO films. Considerable selectivities are shown for the couples CO2/N2 and CO2/CO. © 1995 John Wiley & Sons, Inc.
Grafting of acrylonitrile copolymer membranes with hydrophilic monomers for immobilization of glucose oxidase
Authors: Godjevargova T. , Dimov A. 
Published: April 2003

AbstractPoly(acrylonitrile‐methylmethacrylate‐sodium vinylsulphonate) membranes were subjected to modification by grafting of 2‐dimethylaminoethyl methacrylate (DMAEM) and 2‐acrylamido‐2‐methylpropanesulphonic acid (AMPSA). An Fe2+ H2O2 system was used to initiate the polymerization. Reaction time, temperature, pH, and concentration of an initiator and modifying agent were the variable parameters. Tertiary amino groups, quaternary ammonium groups, and sulfo groups were determined quantitatively by potentiometric titration. The degree of grafting and hydrophilicity and charge density of the modified membranes were studied. Glucose oxidase was immobilized onto modified acrylonitrile copolymer membranes with DMAEM and AMPSA and showed high relative activity. The amount of bound protein and storage of the activity of the immobilized enzyme were determined. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of a monofunctional analog to BIS‐GMA: A dental monomer
Authors: Tamareselvy K. , Rueggeberg F. A. 
Published: April 2003

AbstractA new monofunctional BIS‐GMA monomer, 4‐(2‐phenyl isopropyl)‐3‐phenoxy‐2‐hydroxy propyl methacrylate (monofunctional‐BIS‐GMA, hereafter abbreviated as MF‐BIS‐GMA) was synthesized as an adduct of 4‐cumylphenol and glycidyl methacrylate for use as a dental monomer. The new monomer was characterized by FTIR, 1H, 13C (attached proton test, APT), UV, HPLC, and GPC. The viscosity and solubility of the new resin are also presented. The results were compared with the difunctional analog, BIS‐GMA (2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxypropoxy)]phenyl propane), which is commercially available and currently used in dental restorative materials. Both monomers were light‐cured using 0.3% camphorquinone and 0.75% 2‐(dimethylamino)ethyl methacrylate as photoinitiators. The extent of monomer conversion and the potential for residual monomer leachability were compared between the two cured resins. The monofunctional resin was found to yield higher monomer conversion values (74 vs. 39%) and lower leachable components (0.03 vs. 30.6 mol %) than those of the difunctional analog. © 1995 John Wiley & Sons, Inc.
Solvent concentration measurement for spin coating
Authors: Gu J. , Bullwinkel M. D. , Campbell G. A. 
Published: April 2003

AbstractPlanarization of spin‐coated polymer films is of great importance for the lithographic process in the microelectronic industry. Solvent retention is an important factor for determining the coating profile during spinning. In this research, solutions of polystyrene in toluene are spin‐coated. The coating concentration during spinning is measured on‐line using a laser interferometry technique. The optical measurement is evaluated by an off‐line gel permeation chromatograph technique. The experiments indicate that a smooth coating surface is required to use the optical method for concentration measurement. The optical technique also provides information regarding the coating surface structure during spinning. © 1995 John Wiley & Sons, Inc.
Viscoelastic properties of short carbon fiber thermoplastic (SBS) elastomer composites
Authors: Ibarra L. , Macías A. , Palma E. 
Published: April 2003

AbstractThe determination of viscoelastic property variation in short fiber‐reinforced composites, as a function of strain, temperature, and frequency, constitutes a useful tool when the existence or the strength of matrix–fiber interfaces are to be examined. In this work, these properties are studied in thermoplastic elastomer matrix materials (SBS) filled with commercial carbon fiber (PAN), oxidated, and subsequently treated with diazide, which generates SO2N3 groups on the fiber surface, theoretically capable of chemical reaction with the polymeric chain. For the composite containing diazide‐treated oxidated fiber, certain phenomena have been proven to occur, such as lesser storing modulus losses in case of increasing strain, greater equivalent interfacial thickness values, and higher mechanical energy loss values than those of composite containing oxidated fiber. An increase in glass transition temperature and apparent activation energy of the relaxation process, with respect to composite‐containing commercial fiber, are also observed, which, altogether, allow for the statement that new matrix–fiber bonds are generated through the sulfonyl azide group, conferring greater strength to the interface, although it is less stiff than the one formed with oxidated fiber. Finally, the experimental results are in agreement with those obtained from Huet's rheological model. © 1995 John Wiley & Sons, Inc.
Computer simulation of high‐speed spinning of PET
Authors: Denton Jeffrey S. , Cuculo John A. , Tucker Paul A. 
Published: April 2003

AbstractAn interactive computer simulation of the steady‐state melt spinning of poly(ethylene terephthalate) was developed based upon a combination of physical laws and empirical relationships. The simulation incorporates crystallization effects which makes it valid for a wide range of take‐up speeds. Modifications to the conventional threadline that allow judicious control over the threadline dynamics were modeled and included in the simulation for exploration of the effects of these perturbations. The modifications include quenching and on‐line zone heating. The simulation was verified using experimental measurements of threadline diameter, velocity, and temperature at 3000, 4000, 5000, and 6000 m/min take‐up. Off‐line measurements of crystallinity and birefringence were also compared with the values calculated by the simulation at these speeds. © 1995 John Wiley & Sons, Inc.
The quantitative analysis of fluorocarbon polymer finishes on wool by FT‐IR spectroscopy
Authors: Church Jeffrey S. , Evans David J. 
Published: April 2003

AbstractTwo contrasting infrared spectroscopic techniques, Attenuated Total Reflectance (ATR) and PhotoAcoustic Spectroscopy (PAS), have been investigated as means for the determination of fluorocarbon polymer finishes on wool fabric. Based on the experimental conditions used, the results of the PAS method are more characteristic of the bulk sample, while the ATR results are more surface specific. Linear calibrations between polymer addon, as determined by total fluorine analysis, and the absorbance of the CF stretching bands of the normalized spectral data were obtained for a typical commercial fluorocarbon polymer. The correlation obtained for the PAS method was found to be significantly better than that of the ATR method. The lower limit of detection of fluorocarbon polymers on wool using the PAS technique was 0.25% on the weight of the wool (oww). In contrast, fluorocarbon polymer add‐ons as low as 0.125% oww (approximating monolayer coverage) could be analyzed using the ATR method. At high levels of add‐on, the ATR calibration deviated from linearity. This can be attributed to the distribution of fluorocarbon polymer on the surface of the fiber, in particular, the build up of polymer on the cuticle cell edge regions. The quantitative methods developed are used to help access the effects of wear and the subsequent heating of fluorocarbon polymer‐treated fabric samples. © 1995 John Wiley & Sons, Inc.