bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulations of draw resonance in melt spinning of polymer fluids
Authors: Cao Jinan 
Published: April 2003

AbstractThis article deals with numerical simulations of draw resonance of polymer fluids by employing direct difference methods to solving the governing equations in melt spinning. The stability of each difference method was studied by a comparison of the results obtained from simulations with the theoretical solutions or values. The numerical simulation confirms that the critical draw ratio of draw resonance in an isothermal and uniform tension spinning of a Newtonian fluid is between 20 and 21. The cross‐sectional area of a spinline in draw resonance was found to decrease monotonically from a spinneret toward a take‐up bobbin, although the taken‐up filament shows periodical variation. This study has also illustrated the mechanism of draw resonance previously proposed by the author. © 1993 John Wiley & Sons, Inc.
Viscosity–morphology–compatibility relationship of polymer blends
Authors: Chu Line‐Hwa , Guo Shang‐Her , Chiu Wen‐Yen , Tseng Hsieng‐Cheng 
Published: April 2003

AbstractTo investigate the correlation of viscosity–morphology–compatibility of polymer blends, polystyrene, polybutadiene, and styrene/butadiene triblock copolymer were selected as our materials. A capillary rheometer was used to measure the viscosity. All samples were blended by a two‐roll mill, a Brabender, or by the solution casting method. The morphologies of extruded samples from the capillary were observed by SEM. The relation between the viscosity and the composition of the blend changes with shear rate. It was found that the better the compatability between the two phases of the blend the smaller is the disperse phase domain. The viscosity of polyblends is related to the compatability and composition of the two phase in this blend. In the present study, the rheological behavior of polyblends is explained from the viewpoints of morphology and compatability. © 1993 John Wiley & Sons, Inc.
Effect of L(‐)threonine, 5‐hydroxytryptophane, and 5‐hydroxytryptamine on the ceric‐ion‐initiated grafting of methyl acrylate onto cellulose
Authors: Misra B. N. , Mehta I. K. , Rathore Mahendra Paul Singh , Lakhanpal Sunita 
Published: April 2003

AbstractIn order to study the effect of some radio protecting agents (RPA) such as L(‐)threonine, 5‐hydroxytryptophane (5‐HT), and 5‐hydroxytryptamine on ceric‐ion‐initiated grafting onto cellulose, attempts have been made to graft copolymerize methyl acrylate (MA) in aqueous medium in the presence and absence of RPA. Percentage of grafting has been determined as functions of concentration of (i) ceric ion, (ii) H2SO4, (iii) monomer, (iv) RPA, (v) reaction time, and (vi) reaction temperature. Maximum grafting percentage was obtained at [MA] = 5.53 × 10–2mol/L within 180 min at 45°C in the absence of RPA. Grafting reactions were found to be suppressed in the presence of different RPAs. A plausible mechanism is suggested to explain the observed behavior of RPAs in grafting reactions. The graft copolymers have been characterized by IR spectroscopic and thermogravimetric methods. © 1993 John Wiley & Sons, Inc.
High pressure and low temperature conducting properties of organic semiconducting metal‐anthraquinones
Authors: Vijayashree M. N. , Subramanyam S. V. , Samuelson A. G. 
Published: April 2003

AbstractHigh pressure and low temperature conducting properties of 1,4‐diamino anthraquinone, with metals such as cobalt, nickel, copper, and silver, and reported. The complexes formed are oxidatively and thermally stable and are insoluble in common organic solvents. They possess interesting conducting properties. All are semiconductors, showing conductivity in the range 1.98 × 10−1 to 1.36 × 10−6 S/cm, depending upon the metal atom present in the complex. Low temperature (300 K to 30 K) and high pressure (up to 6 GPa) conductivity properties of these materials are reported. Copper complexes have been studied in detail, as they show interesting conducting properties. © 1993 John Wiley & Sons, Inc.
Rapid stabilization of acrylic fibers using ammonia: Effect on structure and morphology
Authors: Bhat Gajanan S. , Peebles L. H. , Abhiraman A. S. , Cook F. L. 
Published: April 2003

AbstractAcrylic fibers were stabilized, for subsequent carbonization, in oxidizing, inert, ammonia and mixed environments and the stabilized fibers were characterized using several techniques to determine the extent of reactions as well as the morphological changes. Ammonia was shown to accelerate stabilization of acrylic precursors that did not contain other effective initiators, such as acid comonomers. Two effects of ammonia—nucleophilic attack in initiating polymerization of nitrile groups and, possibly, the rapid disruption of lateral order in precursor morphology—combine to produce a significant enhancement in the rate of this intermediate step in the formation of carbon fibers. © 1993 John Wiley & Sons, Inc.
Solubility of cellulose III in sodium hydroxide solution
Authors: Laszkiewicz B. , Cuculo J. A. 
Published: April 2003

AbstractStudies on cellulose III solubility have been conducted in 8.5% NaOH solution with and without the presence of added substances, such as acrylamide, acrylic acid, acrylonitrile, and thiourea. The highest value of cellulose III solubility was obtained as a result of the introduction thiourea and acrylamide in a 5% ratio of NaOH into NaOH solution. Moreover, dissolving conditions proved to be of great importance. Cellulose III introduced into NaOH solution and repeatedly frozen and unfrozen three times dissolved 50% (dissolving with 5% thiourea). The soluble cellulose fraction showed significantly lower molecular mass in comparison with its insoluble fraction. Comparative studies on cellulose crystallinity using the CP / MAS 13C‐NMR method showed a satisfactory compatibility of results with determinations obtained from the X‐ray method. © 1993 John Wiley & Sons, Inc.
Experimental and modeling studies on styrene–butyl methacrylate copolymerization reaction
Authors: Joshi M. V. , Mukesh D. 
Published: April 2003

AbstractRadical‐induced copolymerization of styrene and butyl methacrylate was studied. The effects of the initiator (benzoyl peroxide) concentration, reaction temperature, and poly(vinyl alcohol) amount on the rate of reaction and final product quality are also measured. Kinetics studies and optical microscopy of the reaction mixture indicate that the reaction exhibits autoacceleration behavior, which could be suppressed by reducing the reaction temperature. 1H‐NMR of the intermediate and final product samples reveals the monomer sequencing. The monomer reactivity ratios at various temperatures are estimated from the experimental data. The reaction is mathematically modeled by a Monte‐Carlo simulation, and the results of this analysis are compared with observed data. © 1993 John Wiley & Sons, Inc.
Separation of alcohol–water mixture by pervaporation through a reinforced polyvinylpyridine membrane
Authors: Uramoto Hiromu , Kawabata Nariyoshi 
Published: April 2003

AbstractA membrane consisted of cross‐linked poly(4‐vinylpyridine) and reinforced by a nonwoven cloth made of poly(ethylene terephthalate) was prepared by copolymerization of 4‐vinylpyridine with divinylbenzene in the presence of the nonwoven cloth. Pervaporation performance of this polyvinylpyridine membrane was examined at several feed alcohol concentrations and temperatures. The membrane showed water selectivity, and the permselectivity, αW/A, for the alcohol–water mixture was in the order isopropyl > propyl > tert‐butyl > ethyl > methyl. The membrane showed a large permeability, and the pervaporation flux, ϕ, for the ethanol–water mixture was 7–13 kg/h per square meter of the membrane in pervaporation with sweeping of carbon dioxide under atmospheric pressure and at 40°C. The membrane was durable and long lasting for a prolonged‐period, and permselectivity and permeability of the membrane did not fall off even after repeated use for 1000 h. © 1993 John Wiley & Sons, Inc.
Electrokinetic properties of modified polyester fibers
Authors: Teli M. D. , Prasad N. M. , Vyas U. V. 
Published: April 2003

AbstractElectrokinetic properties of normal polyester flat filament, texturized polyester and cationic dyeable polyester were studied when solutions of different pH and cationic dye concentrations were run through them. The textured polyester exhibited maximum negative zeta potential whereas cationic dyeable polyester showed minimum. The negative zeta potential was found to be maximum near neutral pH. The effect of heat‐setting at extreme conditions (220°C, 90 s) on electrokinetic properties was also studied. Such heat‐setting was found to lower negative zeta potential, attributed to a decrease in surface area. Cationic dyeable, “easy” dyeable, and normal flat filament type polyester were also investigated. Results with respect to negative zeta potential, surface charge density, and surface conductivity, are discussed. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of polyurethane‐polystyrene‐grafted interpenetrating polymer networks using a microgel process
Authors: Chen Hui , Chen Jiann‐Ming 
Published: April 2003

AbstractPolyurethane‐polystyrene‐grafted interpenetrating polymer networks (IPNs) were prepared in the presence of a soluble microgel. The objective was to understand the effect of the microgel on the physical and mechanical properties of the IPN systems. Three types of microgels were prepared by the condensation reaction of various amounts of tolylene diisocyanate (TDI) with linear polystyrene containing hydroxyl groups. The structure of the microgel was determined by gel permeation chromatography and intrinsic viscosity measurement. Increasing the amount of TDI resulted in a microgel having a more compact structure. The dynamic mechanical behavior, mechanical properties, densities, and swelling ratios of the IPNs were determined. Only one broad Tg was observed in each of the dynamic mechanical spectra of the IPNs, whether the IPNs were prepared from microgel or not. This is because of increased compatibility of the two networks by the grafting reaction. Using a microgel to prepare IPNs could further improve the degree of network interpenetration. In addition, higher tensile strength and elongation at break were obtained for the IPNs, when the proper structure of the microgel was used. © 1993 John Wiley & Sons, Inc.
Hybrid‐particulate composites based on an epoxy matrix, a reactive rubber, and glass beads: Morphology, viscoelastic, and mechanical properties
Authors: Maazouz A. , Sautereau H. , Gerard J. F. 
Published: April 2003

AbstractThe deformation and fracture behaviors of hybrid‐particulate epoxy composites have been examined. These materials were based on a DGEBA/DDA matrix with various volume fractions of glass beads and different rubber contents. Young's modulus, yield stress, dynamic mechanical spectra, and fracture energy have been determined at room temperature. The Kerner model fits well the Young's modulus for the hybrid complexes with various glass bead contents. The analysis of the relaxation peak recorded from viscoelastic measurements allow us to discuss the influence of the introduction of the glass beads on the mobility of macromolecular chains and the characteristics of the rubber‐separated phase. The fracture energy displays a strong improvement and a synergism effect due to the presence of both kinds of particules. The toughening mechanisms were discussed. © 1993 John Wiley & Sons, Inc.
Synthesis of plasticizing polyesters of dimer acid and propane–diol
Authors: Bajpai U. D. N. , Nivedita Ms. 
Published: April 2003

AbstractThe polyesterification of dimer acid with propane–diol under different experimental conditions has been studied to obtain the optimum conditions for synthesizing the poly(propane–diol) dimerate plasticizers. The effect of varying molar ratio, temperature, and catalyst concentration on the course of the reaction, acid number, intrinsic viscosity, and molecular weight of the resultant polyester has been investigated. p‐Toluene sulfonic acid (PTSA) was found to be an effective catalyst for the polyesterification reaction. The kinetics of polyesterification in the presence and absence of a catalyst has been found to follow the second‐order rate equation in equimolar concentrations of the reactants. © 1993 John Wiley & Sons, Inc.
Epoxidation of natural rubber in latex in the presence of a reducing agent
Authors: Bac Nguyen Viet , Terlemezyan Levon , Mihailov Marin 
Published: April 2003

AbstractThe in situ epoxidation of natural rubber latex was successfully performed in chain‐scissoring conditions. The chain‐scissoring process could be carried out simultaneously or successively to the epoxidation, to a determined extent. The rate and the degree of epoxidation depend on temperature, pH, and H2O2/isoprene units ratio. The chain‐scissoring reaction leads to a limited intrinsic viscosity range and, at pH 2–3, it was practically completed in 24–40 h. The gel content of epoxidized natural rubber (ENR) products are markedly reduced in the presence of reducing agent. Infrared spectra of ENR, thus prepared, are characterized by the presence of a typical weak band at 1550 cm−1, in addition to the other characteristic bands for normal ENR. At low pH and long‐lasting reaction, the epoxide ring undergoes a ring‐opening process, resulting in the formation of new OH, CO, ether groups, and slightly increased gel content. The Huggins constant, for a typical series of ENR obtained in redox conditions, was determined. © 1993 John Wiley & Sons, Inc.
13C NMR analysis method for urea–formaldehyde resin strength and formaldehyde emission
Authors: Ferg E. E. , Pizzi A. , Levendis D. C. 
Published: April 2003

AbstractA method based on the use of 13C NMR relative peak intensity ratios for different characteristic chemical groups, known or supposed to contribute to urea‐formaldehyde (UF) resin strength and formaldehyde emission is presented. The method relates results obtained by 13C NMR analysis of liquid UF resins with their strength, formaldehyde emission, and percent crystallinity in the resin‐hardened state. Correlation of different peak ratios with experimental results allows the proposal of equations relating the sum of a number of different 13C NMR peak ratios with the three mentioned physical properties of the same resins in their hardened state. Resin strength and percent crystallinity appear to be loosely, inversely related. The equations presented appear to have some applied value in predicting physical properties of hardened industrial‐type UF resins from a single 13C NMR spectrum of the original liquid resins, as well as to render easier comparison between difficult UF resin formulations. This approach has allowed identification of which chemical groups really contribute to the physical properties of the hardened resin, and to what exten. © 1993 John Wiley & Sons, Inc.
Surface activation of polytetrafluoroethylene by bonding of polymeric silicic acid
Authors: Mohammed Mohammed A. , Rossbach Volker 
Published: April 2003

AbstractWhen porous polytetrafluoroethylene (PTFE) is treated in a silicon tetrahalide atmosphere and then hydrolysed by means of a water jet, it is possible to achieve surface activation of the PTFE with silicic acid. This results in the surface of the PTFE becoming completely wettable, particularly if SiCl4 is used. This paper provides an account of the physical and chemical investigation into the surface of the activated system. Measurement of the contact angles (with water) and determination of the silanol groups provide evidence of the surface activity. ESCA experiments show that concentrations of silicic acid above 14% w/w result in almost complete coverage of the PTFE surface. Using the BET method to measure the specific surface area, it can be seen that this is not simply a result of adding the areas of the two components, PTFE and silicic acid. © 1993 John Wiley & Sons, Inc.
Grafting of styrene onto polybutadiene: Calculation of the molecular macrostructure
Authors: Estenoz D. A. , Meira G. R. 
Published: April 2003

AbstractThe radical‐induced grafting of styrene onto polybutadiene at 60°C and in dilute solution is theoretically investigated, with the aim of estimating the detailed molecular macrostructure of the evolving polymer mixture. To this effect, the kinetic mechanism proposed by Brydon et al. [J. Polym. Sci. Polym. Chem. Ed., 11, 3255 (1973) and 12, 1011 (1974)] was extended to evaluate the bivariate weight chain‐length distribution (WCLD) for each of different copolymer topologies generated along the polymerization. Each molecular topology is characterized by two integers: the number of grafted styrene chains and the number of incorporated butadiene chains. Apart from the bivariate WCLDs for every topology and for the total copolymer, the molecular weight distributions of the accumulated polystyrene and of the unreacted polybutadiene are calculated. The model predictions of global variables (monomer conversion, polymer production, average molecular weights, grafting efficiencies, and average number of graft sites per reacted polybutadiene molecule) closely match the experimental measurements in the cited publications. © 1993 John Wiley & Sons, Inc.
Surface and interfacial FT‐IR spectroscopic studies of latexes. VII. EA/MAA latex suspension stability and surfactant migration
Authors: Thorstenson Timothy A. , Tebelius Lara K. , Urban Marek W. 
Published: April 2003

AbstractThis article, part VII in a series of latex studies, focuses on the effect of ethyl acrylate/methacrylic acid (EA/MAA) latex stability on the exudation of sodium dioctyl sulfosuccinate (SDOSS) surfactant molecules after coalescence. It is found that “aging” of the latex aqueous suspension causes excessive exudation of the surfactant molecules to the film‐air interface. Upon exudation to the surface, the surfactant SO Na+ hydrophilic heads assemble in preferentially normal‐to‐the‐surface directions, whereas hydrophobic aliphatic tails are randomly burred in the latex surface. ATR FT–IR spectroscopy and a particle size analysis are utilized to elucidate the effects of flocculation and coalescence on the surfactant mobility in latex films. It appears that flocculation, prior to coalescence, enhances exudation and mobility of the surfactant molecules. © 1993 John Wiley & Sons, Inc.
Gas‐transport properties of ethylene/propylene/carbon monoxide polyketone terpolymer
Authors: Del Nobile M. A. , Mensitieri G. , Nicolais L. , Sommazzi A. , Garbassi F. 
Published: April 2003

AbstractThe demand for heat‐stable and easily processable polymeric materials with good gasbarrier properties is becoming more and more important due to the advent of new technological applications in the field of food packaging. A renewed interest has arisen for a polyketone class of polymers, which seems to fulfill these requirements. Our attention has been focused on a polyketone terpolymer (0.93 : 0.07 : 1 ethylene/propylene/carbon monoxide) in order to determine the transport properties and to relate them to the polymer structure. Permeability tests have been performed at three different temperatures (25, 35, and 45°C) with three different gases (helium, oxygen, and carbon dioxide). Permeabilities, diffusivities, and solubilities have been evaluated. Their dependence on temperature was interpreted on the basis of permeation and diffusion apparent activation energies (Ep and Ed) and of heats of solution (ΔHs). The investigated polymer has been found to be rubbery at the test temperature (glass transition temperature is about 17°C), but the detected permeabilities are comparable to those of glassy polymers widely used for packaging applications. The experimentally determined diffusion coefficients have been related to the semicrystalline nature of the polymer and to the different dimensions of the gas adopted in the investigation. The gas‐solubility coefficients determined from permeability measurements were related to the force constant of the gas molecules in the Lennard‐Jones (6–12) potential field equation. © 1993 John Wiley & Sons, Inc.
Development of a new advanced process for manufacturing polyacetal resins. Part I. Development of a new process for manufacturing highly concentrated aqueous formaldehyde solution by methylal oxidation
Authors: Masamoto J. , Iwaisako T. , Chohno M. , Kawamura M. , Ohtake J. , Matsuzaki K. 
Published: April 2003

AbstractA new technology for the production of highly concentrated aqueous formaldehyde was developed by oxidizing methylal. Whereas the oxidation of methanol yields 1 mol of water per 1 mol of formaldehyde, methylal oxidation produces only 1 mol of water for every 3 mol of formaldehyde. Thus, the output from methylal oxidation is more than 70% formaldehyde compared with 55% from methanol oxidation. For this purpose, basic research for methylal synthesis was tried and the world's first commercial production of methylal was accomplished. Using this methylal, the world's first technology of methylal oxidation for manufacturing highly concentrated aqueous formaldehyde was established by development of a new methylal oxidation catalyst composed of iron, molybdenum, and a third component. This highly concentrated aqueous formaldehyde is then fed to the acetal homopolymer and copolymer plant whose combined capacity is 35,000 tons/years. © 1993 John Wiley & Sons, Inc.
Entanglement fluctuation during phase separation in polymer blends
Authors: Xie Rui , Liang Haojun , Yang Bingxin , Jiang Bingzheng , Zhang Qizhong , Xu Yuanze 
Published: April 2003

AbstractFor perhaps the first time, the dynamics of liquid‐liquid phase separation was studied by time‐resolved mechanical spectrometry in order to establish the relationship between blends' properties and the phase structures during spinodal decomposition (SD). The selected system was chlorinated polyethylene (CPE)/ethylene‐vinyl acetate copolymer (EVA). It was found that in the early and intermediate stage of SD, the storage modulus (G′) and the loss modulus (G″) increase with time after the initiation of the isothermal phase separation; in the later stage, G′ and G″ decrease as phase separation proceeds. An entanglement fluctuation model was presented to manifest this phenomenon; it was found that the rheological behavior agrees well with the expections of the model in the early stage. For the later stage, the reduction of G′ and G″ can be attributed to the increment of phase‐domain size. © 1993 John Wiley & Sons, Inc.
High‐temperature dynamic laser light‐scattering characterization of polyethylene in trichlorobenzene
Authors: Wu Chi , Lilge Dieter 
Published: April 2003

AbstractPolyethylene samples were characterized in trichlorobenzene at 135°C by high‐temperature dynamic laser light scattering (LLS). Precise measurements of the intensity‐intensity time correlation function permit us to make a Laplace inversion to obtain an estimate of the normalized translational diffusion coefficient distribution [G(D)]. After establishing a calibration between the translational diffusion coefficient (D) and molar mass, by using six moderately dispersed polyethylene samples, we were able to transform G(D) to molecular weight distribution (MWD), and to calculate the weight average molecular weight (Mw), which weights were comparable with the ones obtained by using static LLS and size exclusion chromatograph (SEC). The advantages and limitations of using dynamic LLS as a routine method to characterize of polyethylene are discussed. © 1993 John Wiley & Sons, Inc.