bluuebunny/crossref_metadata_2025_split huggingface dataset:
The adiabatic compressibility of poly(acrylic acid) and polyacrylamide in aqueous solution
Authors: Roy‐Chowdhury Phanibhusan , Kale Kalidas M. 
Published: April 2003

AbstractThe results of adiabatic compressibility measurements of poly(acrylic acid) and polyacrylamide along with their corresponding monomers and two poly(sodium acrylates) obtained by neutralizing the polyacid 25% and 100% with sodium hydroxide have been described. The total adiabatic compressibility of poly(acrylic acid) solution is higher than that of the corresponding salt solutions or of polyacrylamide solutions. The unneutralized acid does not dissociate much, even in dilute solution, and the magnitude of electrostriction in polyamide is greater than in acid. The ΦV2 and ΦK2 values for monomers and polymers are seen to be almost concentration independent, and so are the sodium salts of the polyacid. Poly(acrylic acid) and poly(acrylamide) are structurally closely related polymers, and water must be bound to them through polar groups either by hydrogen bonding or by dipole attraction. The hydrophobic part of the solute, because of compact orientation of water and solute in the boundary region, causes a decrease in solvent volume and therefore in the values of ΦV2 and ΦK2. On the other hand, intermolecular hydrogen bonding between the polar groups increases the volume and counterbalances the hydrophobic effect. Because of these two counteracting effects, the observed ΦV2 and ΦK2 values are seen to be concentration independent. Contrary to the observation with poly(methacrylic acid)1 and its sodium salts, the solvated counter‐ions in case of poly(sodium acrylates) make no special contribution in the dilute region. In 100% neutralized polyacid, the dissociation of counterions is complete, and the magnitude of electrostriction is highest in this case. Accordingly, lowest ΦV2 and ΦK2 values (37.0 cc/mole and −50.50 × 10−3 cc bar−1 mole−1) are observed. However, the dissociation and therefore the magnitude of electrostriction are somewhat reduced in the presence of 1.0M NaCl solution; and, accordingly, the values increase to 42.80 cc/mole and −33.0 × 10−4 cc bar−1, mole−1, respectively. The limiting values for the apparent molal volume and the apparent molal compressibility for the polymers show a considerable decrease over those of the monomers. The values of ΦV20 and ΦK20 per methyl group are less in the polymers than in the monomers, and this has been attributed to water clusters that become stronger and better formed as the molecules grow larger and larger. The molar volumes of acrylic acid and methacrylic acid are decreased, while those of acrylamide and methacrylamide are increased when dissolved in water to form an infinitely dilute solution.
Thermal analysis of poly (vinyl chloride) fractions
Authors: Varma I. K. , Grover S. S. 
Published: April 2003

AbstractThe thermal stability of commercial poly(vinyl Chloride) and its four fractions having different intrinsic viscosities (1.152–0.397 dl/g) has been investigated thermogravimetrically in the presence of atmospheric oxygen, up to a temperature of 400°C, by using the nonisothermal technique. The results indicate that the thermal stability of the polymer is inversely proportional to its intrinsic viscosity. The kinetic parameters have been evaluated for the early stages of decomposition (2% to 20%). The results have been explained on the basis of different structures of the polymer chain in fractions of high and low intrinsic viscosity.
A study of fiber extrusion in wet spinning. I. Experimental determination of elongational viscosity
Authors: Han Chang Dae , Segal Leon 
Published: April 2003

AbstractElongational viscosities were measured in a wet‐spinning apparatus. The advantage of this procedure lies in the fact that excellent temperature control can be maintained and that gravity effects can be neglected for a horizontally spun fiber. As a spin dope, an aqueous solution of polyacrylonitrile (PAN) consisting of approximately 10% polymer and 40% sodium thiocyanate (NaSCN) was spun into a coagulating bath of varying NaSCN content, up to a concentration at which spinning was no longer feasible. Fiber diameters were measured photographically as a function of distance from the spinnerette. Spinning tension readings were made on a multifilament bundle using a calibrated tensiometer. To eschew the influence of the hardening effect arising from mass and heat transfer, the temperatures of the spin dope and coagulating bath were kept constant, while the solvent concentration of the coagulating bath was varied up to a maximum limiting value. In this manner, the theoretical condition of no hardening is approached, and the experimentally determined elongational viscosity approaches a limiting, concentration‐independent value. The rheological properties of the spin dope were determined independently in a jet thrust measurement device. Some of the experimentally determined results on elongational viscosity versus rate of elongation were presented and discussed in the light of the theoretical prediction based on various constitutive equations.
A study of fiber extrusion in wet spinning. II. Effects of spinning conditions on fiber formation
Authors: Han Chang Dae , Segal Leon 
Published: April 2003

AbstractA study is carried out to investigate the effects of spinning conditions on fiber formation in the wet‐spinning process. The spinning conditions studied are free velocity (and hence free diameter), throughput rate, maximum take‐up velocity, jet stretch (the ratio of take‐up velocity to free velocity), and filament tension. The coagulating bath temperature and concentration are varied, and three spinnerette diameters are used. The spinning dope is an aqueous solution of polyacrylonitrile in sodium thiocyanate. The present study shows that the coagulating bath concentration influences the spinning tension and maximum take‐up velocity. Two thread breakage mechanisms are postulated which take into account the rate of coagulation, spinning tension, and thread velocity. An attempt is made to predict the concentration profile of solvent in the moving filament by simultaneously solving the mass and force balance equations, in which the increase in elongational viscosity along the spinning way is assumed to be mainly due to the hardening process.
A micro‐macro correlation of ozone‐induced fracture in rubber
Authors: DeVries K. L. , Simonson E. R. , Williams M. L. 
Published: April 2003

AbstractRate of molecular bond rupture is successfully correlated by a Griffith‐type energy balance to the strain energy release rate during ozone cracking of rubber. Rate of bond rupture is determined from electron paramagnetic resonance (EPR) measurements. The rate of strain energy release is determined from stress–elongation measurements during stress relaxation, creep, and cyclic loading tests. To compare with macroscopic crack studies, it was assumed that each ruptured bond created a given amount of fracture surface. Numerical agreement could be obtained by assuming each broken bond results in the production of an area of approximately 10−13 cm2. Using the surface energy density determined from stress relaxation tests in an energy balance gives surprisingly accurate predictions of expected behavior in creep and cyclic loading tests. There is a one‐to‐one correspondence between the rate of crack growth (bond rupture) and rate of energy release from strain and external work in all cases. It is proposed that such correlations give credence to a Griffith‐type approach to environmental cracking which it did not have previously.
Kinetic analysis of radiation‐initiated copolymerization reactions of water‐soluble vinyl monomers with cellulose
Authors: Byrne Geoffrey A. , Arthur Jett C. 
Published: April 2003

AbstractA kinetic analysis of the radiation‐initiated copolymerization reactions of 2‐hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), and methacrylic acid (MAA) from water, methanol (MeOH), N,N‐dimethylformamide (DMF), dimethysulfoxide (DMSO), and combinations of these solvents with irradiated fibrous cellulose I and II was made. The maximum extent of copolymerization of HEMA and HPMA with irradiated cellulose occurred from water solutions. When organic solvents were added to the water solution, while the concentration of monomer was kept constant, the extent of copolymerization decreased. The maximum extent of copolymerization of MAA with irradiated cellulose occurred from mixtures of MeOH (15–30 vol‐%) and water (85–70 vol‐%) solutions rather than from water. After initiation of the copolymerization reactions, they were apparently diffusion controlled and exhibited second‐order kinetics. The relative concentrations of grafted polymer and homopolymer formed with irradiated cellulose from aqueous solutions depended primarily on the concentration of water in the solutions. From MeOH (60 vol‐% or less)–water (40 vol‐% or more) solutions, about 60% of poly(MAA) formed was apparently grafted polymer; from solutions containing less water, the fraction of grafted polymer decreased to about 40%.
Predicting nonlinear viscosity and elasticity from zero‐shear parameters in the Pao‐Rouse model
Authors: Fruh S. M. , Rodriguez F. , Manning A. J. 
Published: April 2003

AbstractWhen the Rouse distribution of relaxation times is inserted into Pao's constitutive equation as expressed by Huseby and Blyler, a simple two‐parameter model results. The parameters can be fitted using the limiting values of viscosity and modulus at low shear rates. The modulus in this case is defined as the ratio of shear stress during steady flow to the recovered shear during creep recovery with the stress removed. The mathematical model, is then used to predict the behavior at high shear rates where flow is pseudoplastic and elasticity is non‐Hookean. A sample of polyisobutylene and several high molecular weight poly(dimethylsiloxanes) can be fitted reasonably well. Silicones of lower molecular weight (3.7 and 5.5 × 105) are not correlated successfully, perhaps because not all the “recoverable shear” stored during flow can actually be recovered experimentally. The Rouse distribution can be generalized for added flexibility.
The conformation of the anhydrocellobiose units in cellulose I and II
Authors: Chü N. J. 
Published: April 2003

AbstractIt is postulated from energetic considerations that the anhydrocellobiose unit in cellulose I has a conformation differing from that in cellulose II. Conformation I has two intramolecular hydrogen bonds, while conformation II has only one. This difference arises from a different orientation of the C(6)‐hydroxyl group in the two conformations. Their interconversion is shown to be dependent upon the polarity of the medium. The assignment of conformation I to cellulose I and conformation II to cellulose II and the equilibrium between them appear to be consistent with a number of experimental observations reported in the literature.
Reactions of wood components with hydrogen sulfide. VIII. Influence of cation and base catalysts on the reductive thiolation reaction at cellulose‐reducing endgroups
Authors: Procter A. R. 
Published: April 2003

AbstractIn the presence of calcium, magnesium, and ammonium ions, the reductive thiolation reaction at cellulose‐reducing endgroups by a hydrogen sulfide–hydrosulfide ion buffer system is more efficient when compared to the sodium base system. The calcium and magnesium base systems show a maximum reaction rate when the buffer pH is 5.9, thus behaving similarly to the previously described sodium base system. In the ammonium base system, however, there is a specific ammonia‐catalyzed reaction with no maximum in the reaction rate over the available pH range. The increased efficiency of the bivalent ion systems is thought to be due to the formation of a salt‐like complex between the cation and an intermediate gem‐dithiol structure in the reductive thiolation reaction scheme. Ammonia enters into the kinetics of the reaction, but the exact mechanism of its action is unclear. Some other nitrogenous bases also catalyze the reductive thiolation. The use of ammonium hydrosulfide to carry out the reductive thiolation reaction is also briefly described.
An investigation of mechanisms of synergistic interactions in PVC stabilization
Authors: Briggs G. , Wood N. F. 
Published: April 2003

AbstractSynergism in poly(vinyl chloride) stabilization has been studied by measuring rates of hydrogen chloride evolution from samples of polymer in the presence of stabilizers in di‐(2‐ethylhexyl) phthalate solution in an inert atmosphere. Barium, cadmium, calcium, and zinc laurates, when used alone, allow escape of hydrogen chloride well before stoichiometric uptake is achieved, whereas synergistic mixtures of calcium–zinc and barium–cadmium laurates absorb almost the theoretical quantity of hydrogen chloride. Cadmium and zinc laurates replace labile chlorine atoms in the polymer backbone by ester groups, reducing formation of long polyene sequences: barium and calcium laurates delay the formation of cadmium and zinc chlorides, apparently by reconverting them into their respective laurates. Polyols function by forming complexes with the prodegradant cadmium and zinc chlorides, but contrary to popular belief phosphites possess little activity in this respect. Instead, they slow down the rate of polymer degradation by removal of labile chlorine atoms, by reaction with hydrogen chloride, and by peroxide decomposition.
The permeation of gases through modified polymer films. IV. Gas permeability and separation characteristics of graft copolymers of polyethylene and teflon FEP films
Authors: Kanitz Peter J. F. , Huang Robert Y. M. 
Published: April 2003

AbstractThe effects of grafting styrene and acrylonitrile onto polyethylene and Teflon FEP films on their gas permeation and separation properties were investigated. The time‐lag method was used to determine the permeability, diffusion, and solubility coefficients of nitrogen and methane gases in the grafted films. The separation factors of nitrogen—methane gas mixtures were measured by gas chromatography. Structural and morphologic changes in the modified films were examined by density, differential scanning calorimetry, and infrared measurements. Attempts were made to relate these changes to the gas permeation and separation characteristics of the films. Modification by graft copolymerization resulted in slightly improved separation factors; however, the permeability and diffusion coefficients decreased. The experimental permeability and diffusion coefficients for gas mixtures were in good agreement with those of the pure components and could be predicted by single gas permeability and diffusion coefficients.
A graphic procedure for obtaining average molecular weights from a chromatogram
Authors: Schrager M. 
Published: April 2003

AbstractA simple graphic method is described for obtaining average molecular weights of a continuously distributed polymer from its GPC chromatogram. The method is based on the assumption that the weight distribution of the polymer may be approximated by a Schulz distribution. As an example, a polystyrene sample is analyzed graphically, and the results are compared with the traditional method of calculation.
Decomposition kinetics of a phenolic–carbon composite. II. Rate relationships
Authors: Auerbach Irving 
Published: April 2003

AbstractThe isothermal decomposition of a phenolic resin in a phenolic–carbon cloth composite was measured in air at 0.1 to 0.2 torr over the temperature range 104–718°C. Two decomposition rate relationships are presented that can be used to predict decomposition. One assumes two second‐order consecutive rate‐controlling reactions, and the other assumes a diffusion‐limited second‐order reaction. Two rate constants govern each relationship, one being operative during the initial decomposition stages, and the other during the final stages. Evidence is presented to support the applicability of both relationships to predict decomposition over the entire temperature range studied. Arrhenius plots of the rate constants consist of several segments linearly connected. Activation energies and frequency factors computed from these segments cover a broad range of values. The activation energies are used to correlate the temperature ranges with the predominant products formed in these ranges.
Thickening of poly(vinyl alcohol) by borate
Authors: Nickerson R. F. 
Published: April 2003

AbstractViscosity and pH of aqueous borate–poly(vinyl alcohol) mixtures were determined under different conditions toward a clarification of the thickening mechanism. Boric acid has little effect on dilute poly(vinyl alcohol) (PVOH), but sodium borate causes sharp viscosity increases which are temperature sensitive and apparently stem from labile exothermic crosslinking of PVOH by borate ions. The pH data indicate that the complexing of borate with simple polyols such as mannitol and glycerol is a different process from borate crosslinking of PVOH. The PVOH thickening and gelling effect probably arises from the replacement of labile waters of hydration on borate ion by OH groups of PVOH rather than from borospirane formation.
Modification of butadiene rubber with 1,3‐dipolar cycloaddition reaction. I. Preparation and properties of the modified polybutadiene
Authors: Tada Koichi , Numata Yoshihiko , Katsumura Toshiaki 
Published: April 2003

AbstractPolybutadiene of lowcis‐content was modified with the precursors of nitrones and nitrile oxide. The carbon‐black‐filled vulcanizates of the modified rubbers containing isoxazolidine and isoxazoline groups showed good tensile properties. The effect of modification was ascribed to the interaction between active sites of carbon black particles and the heterorings.
Effects of corona treatment on composite formation. Adhesion between incompatible polymers
Authors: Blais P. , Carlsson D. J. , Wiles D. M. 
Published: April 2003

AbstractPolypropylene–nylon 6 10 composites were prepared by the in situ polymerization of the nylon monomers on polypropylene films. The adhesion between the nylon and the polypropylene was markedly improved by a brief corona discharge treatment of the films in nitrogen prior to coating. This improvement was demonstrated by an increase in the peel strength of the nylon coating and a decrease in brittleness of photo‐oxidized compesites when corona treatment was used. Adhesive bonding between the nylon and substrate was sufficiently strong to cause cohesive failure in the corona‐treated polypropylene. Only interfacial failure was observed at untreated surfaces. These effects were demonstrated by electron microscopy of the surfaces produced in peel tests. The effects of corona treatment on adhesive bonding characteristics of surfaces are discussed in terms of the chemical and physical changes observed in treated surfaces.
Cellulosates of group ia metals—their preparation and reactivity with β‐chloroethyldiethylamine
Authors: Soignet D. M. , Berni R. J. , Benerito R. R. 
Published: April 2003

AbstractMercerized cotton printcloth converted to a cellulosate of lithium, sodium, potassium, rubidium, or cesium by reaction with metal methoxide is a good substrate for the preparation of diethylaminoethyl (DEAE) cotton at low temperatures in nonaqueous media. The pretreatment to form the cellulosate of the alkali metal does not adversely affect mechanical properties of the cotton fabric. There is no advantage to using a cellulosate other than sodium cellulosate in reactions with β‐chloroethyldiethylamine to form DEAE cotton. The reaction occurs in organic solvents of low and high dielectric constants. The hydrochloride of the amine rather than the free amine can be used to prepare DEAE cotton, provided the ratio of reactants is within specific limits. Consideration has been given to the mechanism of the reaction.
Crack initiation in PVC for subsequent linear elastic fracture mechanics analysis
Authors: Faulkner P. G. , Atkinson J. R. 
Published: April 2003

AbstractReproducible starter‐cracks for subsequent linear elastic fracture mechanics analysis have been grown in PVC by fatigue cycling at 80 Hz. The crack growth rate has been related to the fracture surface markings and to the opening mode stress intensity factor (KI) of the fatigue cycle. Termination of the fatigue crack growth when crack growth rate is constant ensures a smooth mirror fracture surface and a sharp crack tip.
Compatibility of plasticizers with poly(vinyl chloride)
Authors: Wales M. 
Published: April 2003

AbstractThe tendency of a plasticizer to resist exudation from poly(vinyl chloride) (PVC) under compressive stress, known technologically as “compatibility,” is treated in terms of a network model, the plasticized composition being thought of as a rubber crosslinked by crystallites. Compatibility is increased by increased solvency (Flory‐Huggins χ) and decreased by increasing plasticizer molar volume. A large crosslink density and/or insufficient melting of crosslinks during processing (thermal history) also decreases compatibility. All commercial primary plasticizers are believed to be infinitely miscible with amorphous PVC. Phase separation which occurs is syneresis and not related to any phase diagram. Swelling tests for compatibility and swelling measurements on dilute PVC gels are described. Some general principles relating to gel formation and association in polymer solutions are also discussed.
The preparation and purification of diphenylolpropane 4,4′‐dioxyacetic acid (bisacid A2)
Authors: Lenk R. S. 
Published: April 2003

AbstractEarlier work on the synthesis of bisacid A2 is reviewed. The problems associated with the achievement of a pure product in good yield are pointed out. The procedure for obtaining same is described. It is believed that the melting point (or rather melting range) of bisacid A2 prepared from specially pure bisphenol‐A and purified as described is higher than that of any bisacid A2 previously reported in the literature.
The thermal degradation of perfluoropolypyridine
Authors: Cotter J. L. , Dickinson Hilary , Knight G. J. , Wright W. W. 
Published: April 2003

AbstractThe thermal degradation of perfluoropolypyridine was studied in inert and oxidizing atmospheres by thermogravimetric techniques. Volatile products were analyzed mass‐spectrometrically, and the yield of products giving rise to fluoride ion was also determined. The stability of the polymer on a weight loss basis is rather better than that of polytetrafluoroethylene in inert atmospheres, but rather worse in oxidizing atmospheres. The major breakdown route seems to involve removal of the fluorine from the heterocyclic nucleus by a mechanism as yet unknown.
Permeability of polyethylene film to organic vapors
Authors: Laine Roney , Osburn James O. 
Published: April 2003

AbstractThe permeabilities of polyethylene film to vapors of 19 organic compounds at temperatures of 21°C, 38°C, and 49°C were measured by a sorption method. The film was formed into a pouch, which was filled with silica gel, sealed, and suspended in a saturated atmosphere. The permeability was calculated from the steady‐state rate of the gain in weight. The permeability data were correlated with the Hildebrand solubility parameters of the organic substances.