bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyimidazopyrrolones and related polymers. II. Polyimidazopyrrolones from aromatic dianhydrides and 3,3′‐dichloro‐5,5′‐diaminobenzidine
Authors: Bower G. M. , Frost L. W. 
Published: April 2003

AbstractThe preparation of 3,3′‐dichloro‐5,5′‐diaminobenzidine and its polymeric reaction products with pyromellitic dianhydride and 3,4,3′,4′‐benzophenonetetracarboxylic dianhydride are described. The soluble amine–acid–amide form of the polymer is stable at higher concentrations than the corresponding polymers from 3,3′‐diaminobenzidine or 3,3′,4,4′‐tetraaminodiphenyl ether. Infrared spectra indicate that polybenzimidazopyrrolone structure is formed after cure. The preparation and properties of films and glass‐reinforced laminates prepared from the polymers are described.
Sodium cellulosates–preparation from various alkoxides and reactivity toward 2‐chloroethyldiethylamine
Authors: Soignet D. M. , Berni R. J. , Perrier D. M. , Benerito R. R. 
Published: April 2003

AbstractSodium cellulosates were prepared by reacting premercerized cotton fabrics with sodium salts of selected alcohols. The degree of conversion to the cellulosate was related to the Taft polar substituent constant, σ*, of the alkoxide R group. Increase in size of the R group in the alkanol series did not decrease the degree of cellulosate formation. The extent of reaction of the cellulosates with 2‐chloroethylidiethylamine in tertiary butanol to form diethylaminoethyl cellulose (DEAE‐cotton) did not increase with the sodium ion content of the starting cellulosate substrate.
Time–temperature superposition of large‐strain shear properties of the ethylene–propylene copolymer system
Authors: Bahadur S. , Ludema K. C. 
Published: April 2003

AbstractThe principle of time temperature superposition for some mechanical properties of polymers is well known, particularly where strains are on the order of 1% or less. For large strains the simple data transformation techniques are not useful, probably because of morphological changes in the polymer. Morphological changes have the effect of changing the mechanical properties, thus necessitating a shift on the verticle axis as well as horizontal axis where mechanical properties are plotted on the ordinate and strain rate, e.g., is plotted on the abscissa. By the Rouse and Zimm theories of flexible chain polymer molecules a relationship is shown between a verticle shift and a horizontal shift, thereby making it unnecessary to determine the exact nature of morphological changes in the polymer when strained. Six polymers were strained to the fracture point and the shear modulus and fracture strength data were used to demonstrate the technique of simultaneous verticle and horizontal transformation of data.
Polymer encapsulation of colloidal asbestos fibrils
Authors: Xanthos M. , Woodhams R. T. 
Published: April 2003

AbstractThe free‐radical polymerization of several monomers in an aqueous suspension containing chemically opened chrysotile asbestos fibrils was investigated with the intention of promoting complete encapsulation of the individual colloidal fibrils. The degree of polymer deposition on the colloidal substrate is dependent upon several factors including monomer and polymer solubility, initiator type, ionic comonomers, and degree of interfacial wetting. Successful encapsulation was achieved by the addition of novel unsaturated polyelectrolytes which served a dual role as dispersing agent and comonomer. Such methods are useful for the preparation of reinforced composites with controlled interfacial properties. In one example, it is shown that asbestos fibrils surrounded by a rubbery layer can impart greater toughness to a reinforced composite, compared to a composite in which the rubbery phase is dispersed at random or isolated from the interface. The technique can be extended to other types of fillers. The various methods of chemically “opening” asbestos are summarized.
Studies on mixture dyeing. IV. Equilibrium adsorption of direct dyes
Authors: Morita Zenzo , Iijima Toshiro , Sekido Minoru 
Published: April 2003

AbstractChrysophenine G (C.I. Direct Yellow 12), Benzopurpurine 4B (Red 2), Sirius Red 4B (Red 81), Sirius Supra Blue BRR (Blue 71) and Sky Blue 6B (Blue 1) were selected as typical direct dyes, and the equilibrium adsorptions on cellulose (Cellophane) from the 1:1 and 2:1 molar mixture dye baths were investigated at 90° and 70°C. The standard affinity in mixture dyeing was obtained by the equation derived from the assumption of monodispersed and diffusive adsorption. The standard affinity in mixture dyeing was nearly equal to that in single dyeing, except for the Chrysophenine G–Sky Blue 6B system. However, judging from the fiber and solution log sum plots, there was a definite difference between mixture and single dyeing. It was explained by the change of activity of dye and sodium ions on substrate followed by the marked change of the total adsorption. The adsorption behavior of direct dyes is discussed in detail from the viewpoint of concentration dependence of the activity coefficient of dye and sodium ions on the substrate.
Determination of parameters in convected Maxwell model from linear viscoelastic parameters
Authors: Hlaváček B. , Seyer F. A. 
Published: April 2003

AbstractOwing to its simplicity and general ability to correctly portray a number of important flow phenomena, the two‐parameter Maxwell model has been employed in a number of important engineering studies. The relation of this equation to linear viscoelasticity and to some molecular theories is considered. A new rule is developed which shows how the shear‐dependent relaxation time and viscosity of the Maxwell model can be determined from linear viscoelastic parameters. It is thus shown that the two‐parameter Maxwell model may be more general than earlier anticipated.
Esterification of styrene–maleic anhydride copolymer by mixed alcohols
Authors: Aoyagi J. , Shinohara I. 
Published: April 2003

AbstractA copolymer (MW = 1800) of styrene (St) and maleic anhydride (MAn) was esterified with an excess amount of an alcohol mixture, and then the relation between the esterification rates of the individual alcohols and the contents of the esters in the esterific copolymer was examined. At first, the rate constant of an individual esterification was obtained for four different alcohols (n‐butanol, i‐amylalcohol, and benzylalcohol) in a noncatalyst system. Then, the mixed esterification of n‐butanol and i‐amylalcohol was carried out; from the analysis of the ester contents, the following equation was obtained:

From this result, it was concluded that, in esterification with alcohols involving n species, the content of the individual ester can be expressed by the following equation:

where [P] = concentration of esters in the copolymer, [B]0 = initial concentration of alcohols, and k = rate constant of esterification (i,j = 1,2…,n).
Thermo‐optical and differential scanning calorimetric observations of mobility transitions in polystyrene‐poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends
Authors: Shultz A. R. , Gendron B. M. 
Published: April 2003

AbstractTransition temperatures by thermo‐optical analysis (TOA) and by DSC were measured on films of polystyrene (PS), poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO resin) and nine homogeneous blends of these polymers. The TOA procedure consists of automatically monitoring light transmission through birefringent scratches in a film during heating at constant rate in a microscope hot stage between crossed (90°) plane polarizers. The TTOA transition temperature, defined as the temperature of birefringence disappearance in the scratches, increased monotonically from 113°C for pure PS to 222°C for pure PPO resin at a 10°/min heating rate. The Tg (DSC) similarly ranged from 99°C to 212°C at a 20°/min heating rate. The TOA technique as described should be a useful addition to thermomechanical studies of transparent polymers and polymer blends.
Bound rubber in elastomers: Analysis of elastomer‐filler interaction and its effect on viscosity and modulus of composite systems
Authors: Pliskin Irwin , Tokita Noboru 
Published: April 2003

AbstractBound rubber measurement may be very misleading as a measure of elastomer–carbon black interaction because sometimes only part of the apparently bound rubber is truly adsorbed on the carbon black surface. A theory is proposed which utilizes bound rubber measurements, but separates truly adsorbed rubber from other insoluble gel and enables calculation of the adsorbed elastomer layer thickness, a numerical value of interaction. Measurements of interaction were obtained for many different rubbers, including polybutadienes, styrene–butadienes, EPDMs, and butyl, with several different furnace blacks. An equation for viscosity of a rubber–carbon black composite is proposed, based on the degree of interaction obtained from the theory and the possible varying degree of orientation of the composite as the rate of shear is changed. This has been applied experimentally both to soluble elastomers and to an elastomer containing a nonrigid gel. The modulus of a vulcanized composite is shown to be related to the effective volume fraction of filler, which is equivalent to the volume fraction of filler plus adsorbed rubber, at temperatures above the glass transition temperature, regardless of the type of rigid filler. Below the glass transition temperature, the modulus depends only on the filler volume concentration.
Elastic properties and structure of polybutadiene vulcanized with magnesium methacrylate
Authors: Dontsov A. , De Candia F. , Amelino L. 
Published: April 2003

AbstractThe elastic and structural properties of polybutadiene vulcanized with magnesium methacrylate were investigated. Structural information was obtained by x‐ray smallangle diffusion diagrams. Results clearly indicate that in the elastomeric network there is a random distribution of rigid particles. The elastic behavior was analyzed in terms of the Mooney‐Rivlin equation. Experimental evidence for the direct correlation between elastic and structural properties is given.
The effect of molecular weight on the fatigue behavior of polystyrene
Authors: Foden E. , Morrow D. R. , Sauer J. A. 
Published: April 2003

AbstractSignificant improvements in the fatigue life of polystyrene can be realized by increase in molecular weight. In this investigation, samples of polystyrene of varying molecular weight were subject to alternating cycles of axial tension and compression at a test speed of 1600 rpm. One set of fatigue tests was made on samples machined from commercial whole polymer rod. A second set of samples was prepared from a PS standard having an average molecular weight of 160,000 and a narrow molecular weight distribution. A third set of samples had a high average molecular weight of 860,000. For a whole polymer, the S–log N curves tended to have the same general shape as for metals, and the endurance limit appeared to be about 1400 psi. The test results show that the average fatigue life, at any given stress amplitude, is significantly increased by increase in molecular weight. For example, the average life of the high molecular weight standard at any given stress level was found to be more than tenfold that of the low molecular weight standard.
Long‐term stiffening of neoprene pads for the Poseidon missile launch system
Authors: Meier J. F. , Rudd G. E. , Rosenblatt G. B. 
Published: April 2003

AbstractIn a previous paper1 the development of neoprene formulations and mechanical designs to meet operational requirements for the Poseidon launch tube liner pads were presented. Subsequently, it was found that early development pads aged for three months at room temperature were ∼10% stiffer than the vendor's qualification compression–deflection (CD) test values. The increase was attributed to a combination of normal elastomer recovery and continued crosslinking due to the original low state of cure of the pads. A program was designed to study the effect of postcure time and temperature on CD recovery, the effect of carbon black loading on the CD recovery, and room temperature and accelerated aging at elevated temperature on these effects. Values of the molecular weight between crosslinks (M̄c) were determined experimentally to establish the state of cure. The results of these experiments are presented and discussed. Recommendations are given for reducing CD variation by modifying carbon black loading and/or postcure conditions.
Protection against intense light. II. The role of the gaseous decomposition products
Authors: Prosser R. A. , Stapler J. T. 
Published: April 2003

AbstractScreening studies have shown that of a series of halogenated vinyl polymers, poly(vinylidine fluoride) gives comparatively good thermal protection when exposed to the intense light energy of the carbon are‐image furnace. Results indicate that this protection is undoubtedly provided by polyenes, (CHCF)n, formed during pyrolysis. Decomposition products containing these structures are expelled by the gases formed into the region between the light source and the target where they intercept photons from about 200 to 500 mμ and dissipate the energy to the air as heat and/or reradiate it. Instrumental evidence for polyene formation is given. The concept of polyene formation clarifies the relative thermal protection offered by a series of vinyl polymers.
A new approach to coagulation phenomena in wet‐spinning
Authors: Rende A. 
Published: April 2003

AbstractA new physicochemical model was built to describe the phenomena occurring during wet‐spinning of polyacrylonitrile, in order to relate the integral time of coagulation to the major variables of the spinning bath. According to this model, counterdiffusion of solvent and coagulant leads the system to overcome the thermodynamic equilibrium conditions, so that precipitation of polymer occurs, at a distance from the fiber axis variable with time. This causes a moving‐interface dope‐coagulated polymer to build up. The integral time required by this interface to reach the fiber axis, i.e., the coagulation time, is related, by simple equations to initial radius, to temperature via diffusional coefficients, to “bath hardness” (i.e., coagulant content), and to thermodynamic phase equilibrium conditions.
Photo‐oxidation of polypropylene films. VI. Possible UV‐stabilization mechanisms
Authors: Carlsson D. J. , Suprunchuk T. , Wiles D. M. 
Published: April 2003

AbstractThe effects of the chemical nature, concentration, stability, and location of various additives on the ultraviolet stability of polypropylene are discussed. It is shown that effective stabilizers of thin films do not depend on UV absorption for their protective action, whereas some relatively inefficient additives operate solely as UV screeners. Adequate UV protection was observed when small amounts (∼0.01 wt‐%) of effective stabilizers were concentrated in or on the surfaces of commercial films, and the remaining bulk of the film contained only a very low concentration (∼0.01 wt‐%) of uniformly blended additive. Previous attempts at demonstrating energy‐transfer stabilization of the polymer are discussed with reference to the present data; it is concluded that effective polypropylene stabilizers probably operate by a combination of chromophore quenching, radical scavenging, and hydroperoxide decomposition.
Effect of solvents on the degradation of polymers by high‐speed stirring
Authors: Nakano Akihiko , Minoura Yuji 
Published: April 2003

AbstractThe effect of solvents on the degradation of poly(methyl methacrylate), polystyrene, and polyisobutylene by high‐speed stirring (30,000 rpm) at 30°C was studied. From the intrinsic viscosities of polymers stirred for given times, the viscosity‐average degree of polymerization, P̄v was obtained and the number of scissions per molecule, B/n0. was calculated. Ovenall's equation

could be applied to the results, where dBi/dl is the rate of breakage of molecules of ith degree of polymerization, ni is the number of molecules present, PI is the limiting degree of polymerization, and ki is a rate constant; k and PI were changed with solvents, and were found to have no relation to the physical properties of the solvents but to the intrinsic viscosities the polymers showed in the solvents used for the stirring. k was smaller and PI larger for solvents where polymers had larger intrinsic viscosities. This relation implies that the degree of expansion of a polymer coil in a solvent is closely related to the rate constant of scission and to the limiting degree of polymerization.
Radiation crosslinking of poly(vinyl chloride)
Authors: Salmon W. A. , Loan L. D. 
Published: April 2003

AbstractThe mechanism of the electron irradiation crosslinking of poly(vinyl chloride) (PVC) with polyfunctional acrylic monomers has been investigated as part of a program to develop an insulation for distributing‐frame wire. These monomers were found to undergo rapid polymerization to form a rigid, three‐dimensional network onto which PVC was grafted. Polyfunctionality was necessary for crosslinking to occur, since butyl methacrylate, containing only a single unsaturated bond, did not crosslink readily. On the other hand, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate, each containing three unsaturated groups, gave extremely rapid crosslinking. Trimethylolpropane triacrylate showed 40 times the radiation sensitivity of tetraethylene glycol dimethacrylate, a diunsaturated compound. The rate of disappearance of unsaturation was related inversely to the rate of gel formation. This was attributed to immobilization of unreacted pendant double bonds in the rigid crosslinked network. In the triunsaturated monomers, half the vinyl groups were left unreacted when all of the PVC was insoluble.
The thermal degradation of hydrofluoro polymers
Authors: Knight G. J. , Wright W. W. 
Published: April 2003

AbstractThe evolution of hydrogen fluoride (or other degradation products giving rise to Fions in aqueous solution) from a number of hydrofluoro polymers has been studied in nitrogen or air over a range of temperatures using a fluoride ion selective electrode to monitor the process. The results in an inert atmosphere illustrate the effect of chemical structure upon the relative ease of hydrogen fluoride elimination.
The action of tridecyl phosphite in the stabilization of poly(vinyl chloride) with metal soaps
Authors: Hybart F. J. , Rowley G. N. 
Published: April 2003

AbstractThe effect of tridecyl phosphite on the stabilization of the thermal degradation of poly(vinyl chloride) under nitrogen by cadmium and zinc stearates has been studied. The rate of evolution of hydrochloric acid from solutions of the polymer with stabilizers in dioctyl phthalate at 190°C has been measured. Tridecyl phosphite absorbs HCl and is converted into the phosphonate which reduced the deleterious action of the cadmium and zinc chlorides formed from the stearates.
Free volume and the annealing and antiplasticizing of bisphenol A polycarbonate
Authors: Robertson Richard E. , Joynson Catherine W. 
Published: April 2003

AbstractAnnealing below the glass transition temperature and the addition of an antiplasticizer are each known to increase the yield stress and the density of glassy bisphenol A polycarbonate. We have studied the combined effects of annealing and antiplasticizing to see if the individual effects would interfere with one another, as might be expected if the same free volume were involved in each. We find that the effects, even when they individually approach saturation, remain additive. This suggests that the free volume in the glass has at least two parts, one of which is affected by annealing and the other by antiplasticization. The available data indicate that the rate at which the yield stress changes with measured volume is different for the two parts.
The thermal degradation of perfluoro polymers
Authors: Knight G. J. , Wright W. W. 
Published: April 2003

AbstractA number of perfluoro polymers were heated at a constant rate of temperature rise in an atmosphere of nitrogen or air, and the volatile degradation products were passed into an aqueous solution, where the F− ions produced were monitored with a fluoride ion‐selective electrode. Compounds giving rise to F− ions were formed in both nitrogen and air, but in larger amounts in the latter atmosphere. For the formation of appreciable quantities of F− ions, temperatures greater than 500°C were normally necessary.
Thermal polymerization of styrene at high conversions and temperatures. An experimental study
Authors: Hui Albert W. , Hamielec Archie E. 
Published: April 2003

AbstractAn experimental study of thermal polymerization of styrene in the temperature range 100–200°C and conversion range 0–100% is reported. Conversions, molecular weight averages, and molecular weight distributions were measured. A kinetic model with third‐order initiation gives a satisfactory fit of conversion and number‐ and weightaverage molecular weights over the ranges of temperature and conversion investigated. This model should find use in the design, simulation, and optimization of polystyrene reactors.
The role of membrane pressure in reverse osmosis
Authors: Paul D. R. 
Published: April 2003

AbstractLiquid transport occurs through reverse osmosis membranes as a result of an applied pressure differential. The pressure within the membrane continuum is an important thermodynamic parameter in the formulation of solution‐diffusion models for this process. It is shown that this membrane pressure is the same throughout the membrane for supported flat and tubular membranes and for hollow fibers. The use of this parameter in calculating the induced concentration differential is discussed.
Spectroscopic examination of ethylene–propylene–norbornenic diene terpolymers
Authors: Tosi C. , Ciampelli F. , Cameli N. 
Published: April 2003

AbstractInfrared methods for the analysis of the third monomer in ethylene–propylene–norbornenic diene terpolymers were developed. They are based either on the CC stretching vibration near 6 μ or on the CH out‐of‐plane deformation vibration between 11 and 12 μ. Calibration was made by NMR on selected samples with high unsaturation content. Particular emphasis was laid on terpolymers with ethylidene norbornene, for which the reliability of the analysis for the third monomer was checked by several techniques, and the transferability to the determination of propylene of the calibration curves set up for the analysis of composition in ethylene–propylene copolymers was studied.
Effect of stirring on the emulsion polymerization of styrene
Authors: Nomura Mamoru , Harada Makoto , Eguchi Wataru , Nagata Shinji 
Published: April 2003

AbstractThe purpose of this paper is to clarify the effect of stirring on the course of emulsion polymerization of, for example, styrene. It establishes the existence of an optimum range of stirring speed and three important factors which must be considered in carrying out emulsion polymerization. (1) Stirring significantly affects the course of reaction in the presence of an imperfectly purified nitrogen atmosphere. Consequently, the number of polymer particles produced and the polymerization rate per particle will be affected. (2) At higher stirring speeds, polymer particles coagulate and coalesce. At lower stirring speeds, the reaction rate is controlled by the monomer transport rate from monomer droplets to the aqueous phase. (3) Stirring contributes to the reduction of the number of micelles because emulsifier molecules are adsorbed onto the surfaces of monomer droplets finely dispersed by the stirring. At low emulsifier concentrations near the critical micelle concentration, this effect cannot be neglected.