bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basic dyeability and acid content of high‐conversion polyacrylonitrile
Authors: Peebles L. H. , Thompson R. B. , Kirby J. R. , Gibson M. E. 
Published: April 2003

AbstractPrevious data have shown that the basic dyeability of acrylic polymers increases at a given specific viscosity as the peroxydisulfate‐to‐bisulfite ratio, that is, the catalyst‐toactivator (C/A) ratio, is increased. This study represents an effort to understand better the role of the initiator system on the basic dyeability, the acid group composition, and the chain composition of acrylic polymers by preparing model polymers with radioactive initiators. As the C/A ratio is increased, the molecular weight distribution broadens as measured by the M̄v/M̄n ratio, the latter obtained by osmometry. There is also a significant effect of both C/A ratio and molecular weight on the sulfate group content per molecule, but there is no effect of C/A ratio on the number of basic dye sites per molecule, the number of sulfonate groups per molecule, or the weak acid groups per molecule. These effects can be explained by invoking a chain transfer to activator reaction in addition to the usual method of chain termination by recombination. The basic dyeability is found to correlate with the number‐average molecular weight and with the number of strong acid groups plus the nonchromophoric weak acid groups.
A valid method of calibration which includes correction for dispersion in gel permeation chromatography
Authors: Swartz T. D. , Bly D. D. , Edwards A. S. 
Published: April 2003

AbstractTwo independently derived distribution function methods validate both the calibration curve and the dispersion correction of the “effective linear calibration” method used in gel permeation chromatography (GPC). Experimental conditions are specified for making the method more useful by permitting linear extrapolation of the calibration line,

and for using a minimum number of standards. The independent methods quantitatively relate known differential of integral distribution functions for standard samples to their respective chromatograms. As such, they are useful calibration methods also, but are limited in scope and range.
Melt rheology of high‐density polyethylene
Authors: Fujiyama Mitsuyoshi , Kagiyama Yasuhiro 
Published: April 2003

AbstractThe melt rheology of high density polyethylene was investigated. Linear viscoelasticity, capillary flow properties, and molecular weight parameter were measured with a plate relaxometer, capillary rheometer, and gel permeation chromatography, respectively. Intimate correlations among the slope of relaxation modulus curve, non‐Newtonian flow behavior, Barus effect, and molecular weight parameter, Mz(Mz+1)/Mw, respectively, were found.
Difficulties associated with the measurement of the diffusion coefficient of solvating liquid or vapor in semicrystalline polymer. I. Permeation methods
Authors: Blackadder D. A. , Keniry J. S. 
Published: April 2003

AbstractThe diffusion coefficients D for solvating liquids and vapors in membranes can be measured in a number of ways. The effectiveness of permeation methods for systems involving semicrystalline polymers at near‐ambient temperatures has been assessed, and new experiments have been performed using p‐xylene and high‐density polyethylene. The conclusions are likely to apply to any semicrystalline polymer where the diffusant concentration is not zero. Stresses induced in the downstream side of the membrane by solvent sorption at the upstream surface during the nonsteady period are shown to lead to underestimation of D. The rate of attainment of a steady state is controlled primarily by the rate at which these stresses relax. The extremely slow rate of stress relaxation in polyethylene implies that, under many experimental conditions, a true steady state of permeation is not attained within an experimentally accessible time, a conclusion supported by experimental evidence. Diffusion coefficients calculated in the usual way from apparently steady‐state permeation rates may be grossly underestimated. In liquid permeation experiments, some of the polymer may dissolve in the upstream permeant, and this may lead to overestimation both of the time to reach an apparently steady state and of the steady‐state permeation rate itself.
Characterization of functionally terminated polybutadienes of low molecular weight
Authors: Ahad Elie 
Published: April 2003

AbstractA difunctional hydroxyl‐terminated polybutadiene (sample A) was characterized by light scattering (LS), vapor pressure osmometry (VPO), and gel permeation chromatography (GPC). Sample A was then esterified, and the product (sample B) was also characterized. Light‐scattering measurements were carried out in different solvents (some were theta solvents for polybutadiene), and the results were corrected for anisotropy. Values of Mn (3100) and Mw (8000) determined respectively by VPO and LS for samples A and B were similar to those computed by GPC using two sets of columns of different resolution. The value of 2.3 found for the polydispersity index Mw/Mn is higher than the value which is usually reported by other workers (ca. 1.3 to 1.7) for functionally terminated polybutadienes.
Photolysis of poly(p‐methylstyrene)
Authors: Weir N. A. 
Published: April 2003

AbstractPoly(p‐methylstyrene) films have been irradiated with 253.7‐nm radiation under high vacuum at 25°C. The main reaction product is hydrogen, but methane and traces of ethane and monomer were also detected. The quantum yield for H2 production (6 × 10‐2) is considerably greater than that for polystyrene photolysis indicating that both α‐CH bonds undergo fission. Solubility measurements also indicated the participation by the p‐methyl group. Main‐chain conjugation and coloration occur and are attributable to hydrogen abstraction from the β‐carbon atom. Cyclohexadienyl compounds are also formed and are presumably associated with crosslinking involving addition to the benzene ring. The mechanisms of photochemical and photophysical processes are discussed.
The graft copolymerization of styrene and lignin. III. Chain transfer reactions of lignin and lignin model compounds
Authors: Phillips R. B. , Brown W. , Stannett V. 
Published: April 2003

AbstractThe effect of addition of lignin model compounds on the polymerization rate and molecular weight of polymer in the radiation‐induced polymerization of styrene was studied. Guaiacol, a model for softwood lignin, reacted slowly with styrene radicals, while 2,6‐dimethoxyphenol, a hardwood lignin model, was a much more efficient chain transfer agent. Studies with isoeugenol indicate that allylic or phenoxy radical stability in a conjugated system may terminate polymerization quite effectively. The results are discussed in the light of new and previous data with isolated lignins; they are consistent with the previously presented grafting scheme.
Pyrolysis and combustion of polyester. I. Thermochemistry of poly(1,4‐cyclohexylene dimethylene terephthalate) treated with selected phosphorus‐ and halogen‐containing flame retardants
Authors: Bostic James E. , Yeh Kwan‐Nan , Barker Robert H. 
Published: April 2003

AbstractA series of poly(1,4‐cyclohexylene dimethylene terephthalate) (PCHDT) fabrics treated with selected phosphorus‐ and halogen‐containing flame retardants has been studied by static oxygen bomb calorimetry. The amount of heat evolved when these fabrics are burned in the open atmosphere has been determined indirectly using calculations based on Hess' law of summation. This heat evolution when corrected for contributions due to burning of the flame retardant appeared to correlate with the efficiency of the flame retardant treatment and was interpretable in terms of mechanisms of flame retardant action. Also, this technique has been applied to blends containing polyester.
Grafting onto wool. III. Relationship between alpha‐ and beta‐forms in wool keratin of grafted fibers
Authors: Arai Kozo , Negishi Michiharu , Suda Tsutomu , Arai Shinji 
Published: April 2003

AbstractA quantitative study of the change in the x‐ray intensity diffracted from the α‐ and β‐crystalline phases of grafted fibers was carried out. It was demonstrated that a part of the α‐helical sections is disrupted by the deposition of polymer and that during extension processes a marked stabilization for the remainder results from the interaction between the residues on the α‐helix and the rigid polymer chain. It was also considered that the disrupted sections are identical to the portions which would be easily deformed by stretching. The results on fibers containing hydrophilic polymer suggested little possibility that the β‐chain crystal is produced from the disrupted chains of α‐crystallites. The mechanism of the so‐called α–β transformation was proposed as ⇌ α M, M* ⇌ β.
Interpretation of the enhanced solubility of poly(vinylidene chloride) in certain solvent mixtures
Authors: Wessling R. A. 
Published: April 2003

AbstractThe 3‐component mixture poly(vinylidene chloride)—tetramethylene sulfoxide–tetrahydrophalene has been investigated by viscometric methods. This solvent pair shows an unusal affinity for the polymer. This can be attributed to the strong polar interaction between the acidic polymer and the basic sulfoxide which is enhanced by the presence of the nonpolar diluent.
The quantitative detection of free radicals on mechanically formed polymer surfaces
Authors: Salloum Robert J. , Eckert Roger E. 
Published: April 2003

AbstractMechanochemical reactions are becoming increasingly important; yet, quantitative data on mechanoradicals are sparse. A study was undertaken to determine the surface concentration of free radicals which are available for reaction when chemical bonds are broken by mechanically forming fresh polymer surface. Polyethylene and polypropylene were cut under a benzene solution of the free‐radical scavenger diphenylpicryl‐hydrazyl, using countersinks as the cutting tools. Accurate surface area measurements of the polymer shavings were made. Surface free‐radical densities up to 2 × 1013/cm2 for polyethylene and 9 × 1013/cm2 for polypropylene were determined. The physical conditions of the test and of the cutting tool were found to have an effect on the results, but not as profound as that of base polymer.
Polymerization of benzene in a capacitively coupled RF plasma
Authors: Duval M. , Théorêt A. 
Published: April 2003

AbstractThe influence of various parameters on the polymerization reaction of benzene in a capacitively coupled rf plasma has been investigated, with particular emphasis on coatings structure and quality. Molecular weight distribution studies by gel permeation chromatography indicate that the degree of polymerization is mainly influenced by pressure and power. A two‐stage mechanism of polymer formation is proposed on the basis of experimental data: oligomers or polymers are first formed in the gas phase and then diffuse to the electrodes and reactor walls, where they may undergo an emulsiontype polymerization. Sputtering and pyrolysis effects are suggested to explain the additional observations on the lowest‐and highest‐pressure films.
Further studies on the action of alkali metal hydroxides on cotton
Authors: Zeronian S. H. , Cabradilla K. E. 
Published: April 2003

AbstractX‐Ray diagrams revealed that the conversion of the lattice structure from cellulose I to cellulose II is substantially complete in cotton treated at 0°C with LiOH, NaOH, or KOH of approximately 5N concentration. With concentrations less than 5N, there were marked differences in the ability of these reagents to cause lattice conversions in cotton. Below a minimum concentration which is dependent on both the alkali and the treatment temperature, conversion from cellulose I to cellulose II cannot take place in cotton irrespective of the swelling caused by the reagent. We suggest that extensive swelling by one of these alkalis is not sufficient by itself to cause conversion from cellulose 1 to cellulose II and that the concentration of the alkali is of prime importance. There was no direct relation between the swelling induced in cotton by treatment with LiCH, NaOH, or KOH at 0°C and the sorption ratio of the resulting product. Also, although treatment with 5N KOH caused less swelling than that obtained with either 5N NaOH or LiOH, KOH reduced the level‐off degree of polymerization (LODP) of cotton most, indicating the importance of the size of alkali cation in reducing crystallite length. In additional experiments, cotton was treated at 21°C with a solution of 4.7N NaOH to which boric acid had been added. Although the swelling of the cotton was little affected, the addition of the boric acid caused the sorption ratio of the product to decrease, whereas the LODP increased. Also conversion of the lattice structure from cellulose I to cellulose II was inhibited.
The preparation of crystalline polypropylene sodium sulfonates and their interaction with an included sodium hydroxide phase
Authors: Huff T. , Johnson B. H. 
Published: April 2003

AbstractSodium sulfonated polypropylenes have been prepared by the slurry chlorosulfonation of polypropylene or propylene—ethylene copolymer followed by hot aqueous sodium hydroxide treatment. Low levels of excess sodium hydroxide were added to the materials to stabilize them against thermal decomposition. It was found that there was a strong interaction between the sodium hydroxide phase and the polymer sodium sulfonate groups which persisted above the nominal melting point of crystalline polypropylene. Evidence for the interaction includes an increased melt viscosity and a greatly increased nucleation rate for the composites as compared to the polypropylene sodium sulfonates not containing the sodium hydroxide phase. The composites have an improved balance of mechanical properties as compared to the materials from which they are prepared.
Thermoelastic properties of block copolymers of the polystyrene–polybutadiene–polystyrene type
Authors: Pollàk V. , Romanov A. , Marcinčin K. , Vyroubal Č. 
Published: April 2003

AbstractThe thermoelastic properties of block copolymers of the type polystyrene—polybutadiene—polystyrene were studied. It was found that the fu values depend on the content of styrene and the strain history as well. These relationships are discussed from the point of view of polymer structure.
Flame‐retardant cotton fabrics by reaction of cellulose with phosphorus trichloride–DMF adduct
Authors: Vigo Tyrone L. , Collins Anna M. , Welch Clark M. 
Published: April 2003

AbstractCotton sateen fabric was found to react with the 1 : 2 adduct of phosphorus trichloride and N,N‐dimethylformamide (DMF) in DMF or DMF—chloroform solutions at room temperature. During this reaction, the fabric acquired flame resistance. The introduction of as little as 1.2% phospohorus and 0.4% nitrogen, achieved at adduct concentrations as low as 2–5% in reaction times of 5–30 min, was sufficient to impart a useful level of flame retardancy. The effect of the adduct concentration, reaction time, and wash procedures on the flame resistance and other properties of the resultant cotton fabrics was studied. Moderate increases in the wet and dry wrinkle recovery were imparted by the treatment, but the use of high concentrations of adduct were somewhat detrimental to the tensile strength of the fabric. However, adduct concentrations of 20–25% produced a rather durable finish which passed the standard vertical flame test after 20 home launderings. Gradual loss of flame resistance during repeated laundering is attributable to ion exchange properties gradually acquired by the fabric. Based on analytical and in frared spectral data, the initial reaction of cellulose with the PCl3—DMF adduct is thought to involve elimination of one mole of DMF to form celluloseOP linkages, as well as some cellulose crosslinking via a second formimidate group of the adduct. Gradual hydrolysis during multiple launderings apparently yields cellulose acid phosphates responsible for the calcium ion uptake and decrease in flame resistance.
The effect of sodium hydroxide on crystallite orientation measurements in cotton fibers
Authors: Hebert Jacques J. , Muller Linda L. , Schmidt Richard J. , Rollins Mary L. 
Published: April 2003

AbstractThe crystallite reorientation brought about by the swelling of cotton with sodium hydroxide solution (NaOH) has been investigated. The degree of reorientation as indicated by the decreased value of x‐ray angle may arise from deconvoluting and not necessarily from a change in orientation of the crystallites within the fibrillar structure.
Viscoelastic properties of aqueous solution of methylcellulose
Authors: Amari Takeshi , Nakamura Matao 
Published: April 2003

AbstractThe viscoelastic properties of aqueous solution of methylcellulose were investigated using three types of rheometers, which enabled us to cover more than 8 decades of frequency range. At first, the entanglement densityX/qat various temperatures was estimated by comparingG′, andG″ curves and relaxation spectra experimentally obtained with those calculated from Hayashi's theory. At lower temperatures, the concentration dependence ofX/qwas small as observed for polyelectrolytes, but increased at higher temperatures. The same tendency was observed in the concentration dependence of the entanglement functionGeN.It is supposed that water molecules adsorbed on methylcellulose and depressing the entanglement formation dissociate with increasing temperature. The relaxation mechanism was then examined from the concentration dependences ofG′, η′, and ηo at various temperatures and frequencies. It is concluded that the structural networks in a solution become closer with increasing temperature, and the corresponding viscoelastic mechanism varies from the intermolecular interaction such as entanglements to the intramolecular motion with increasing frequency.
Gas‐Filled polymers. II. Mechanical behavior of polyethylene
Authors: Kolbeck A. G. , Uhlmann D. R. , Calvert P. D. 
Published: April 2003

AbstractThe mechanical properties of gas‐filled polyethylene have been studied for material with density greater than about 0.85 g/cm3. The effect of gasification on the tensile properties of both high and low density polyethylene beyond a certain critical density reduction is to cause a general weakening of the material. The yield stress falls by about 25% over the range of density investigated, while the elongation to fracture decreases by an order of magnitude. A mechanism is proposed to this weakening and for the yielding and fracture phenomena observed for gasified polyethylene.
Interpolymer from starch xanthate and polyamide–polyamine–epichlorohydrin resin: Structure and papermaking application
Authors: Carr M. E. , Doane W. M. , Hamerstrand G. E. , Hofreiter B. T. 
Published: April 2003

AbstractThe efficacy of oxidatively crosslinked starch xanthate for improving wet‐ and dry‐strength properties of paper prompted the present study of an alternative, interpolymeric crosslinking procedure. Sodium starch xanthate of degrees of substitution 0.05–0.25 was reacted with a commercial paper additive (a polyamide–polyamine–epichlorohydrin wet‐strength resin) which was found to contain 3‐hydroxyazetidinium chloride, epoxy‐propyl, and chlorohydrin groups (3:1:1) to give an interpolymer crosslinked by both ionic and covalent bonds. Model systems, in conjunction with nuclear magnetic resonance, infrared, and ultraviolet spectral data, served to elucidate reaction mechanisms and structures of the interpolymer and the commercial resin. Reaction conditions that favored formation of either ionic (polysalt) or covalent (xanthate ester) crosslinks were investigated. In preliminary evaluations, incorporation of the interpolymer into paper handsheets resulted in excellent wet‐ and dry‐strength improvements.
Redox sensitization in the photochromic polymers of the thionine series
Authors: Kamogawa Hiroyoshi , Hasegawa Haruo 
Published: April 2003

AbstractThe incorporation of electron‐donating components such as mono‐, di‐, and triethanolamines into the thionine photoredox system was tried (1) by copolymer preparations containing the acrylamidomethylthionines and triethanolamine monoacrylic ester as components, (2) by the reaction of triethanolamine and thionines with the N‐hydroxy‐methyl group in polymer in an acid medium, and (3) by the reaction of mono‐ or diethanolamine and thionines with the N‐hydroxymethyl group. The photochromic behavior incorporated into the polymer chain are as effective as their monomeric equivalents, to the extent that the sensitivity is among the highest so far investigated.
Anisotropic shrinkage of injection‐molded rubber
Authors: Nakashima Kunihiko , Fukuta Hiroshi , Mineki Minoru 
Published: April 2003

AbstractThe anisotropic characteristics of injection‐molded flat rubber sheets were investigated. The shrinkage and mechanical properties were measured in two directions: parallel and perpendicular to the flow direction. The results showed that (1) the shrinkage in the parallel direction is larger than that in the perpendicular direction, (2) such anisotropic shrinkage increases with the increase of vulcanization temperature and flow distance, (3) similar anisotropy was also noticed in 300% modulus, tensile strength, and elongation. Two kinds of orientation, “shear orientation” and “expanded orientation,” were observed. The former occurs by plug flow, and the latter by the expansion of the materials. The shrinkage was independent of the expanded orientation but was strongly associated with the shear orientation, while the mechanical properties were affected by the expanded orientation.
Polymer deposition onto the support in column fractionation
Authors: Ogawa Toshio , Tanaka Shoichi , Inaba Tadami 
Published: April 2003

AbstractThe effects of the depositing condition in column fractionation of isotactic polypropylene were studied in detail. A good fractionation was accomplished not only in selective but also in nonselective deposition. Furthermore, it was found, in opposition to Kenyon's opinion, that the polymer was not spread uniformly over the support, but deposited onto the support in the state of particles and that fractionation was not successful in the case of large particles. From these facts, the particle size is regarded as an important factor to attain good fractionation of isotactic polypropylene.
Formalized poly(vinyl alcohol) membranes for reverse osmosis
Authors: Chen C. T. , Chang Y. J. , Chen M. C. , Tobolsky A. V. 
Published: April 2003

AbstractThe permeation properties of formalized poly(vinyl alcohol) membranes are described. The interest of this work is centered on the properties relevant to desalination by reverse osmosis. These membranes, when properly prepared, showed reasonably high water permeability, high salt rejection, and stability in the presence of acids and alkalies.
Effect of molecular structure on polyethylene melt rheology. III. Effects of long‐chain branching and of temperature on melt elasticity in shear
Authors: Mendelson R. A. , Finger F. L. 
Published: April 2003

AbstractThe effects of long‐chain branching and of temperature on the melt elasticity in shear of polyethylene were investigated using die swell measurements and relating them to recoverable shear strain, normal stress, and shear modulus. Die swell measurements, as a function of shear rate, were obtained for high‐ and low‐density polyethylenes at temperatures ranging from 130° to 225°C. The samples were characterized by GPC and intrinsic viscosity for molecular weight distributions and degrees of long‐chain branching. The importance of annealing the extrudates at temperatures above the polymer melting temperature to achieve equilibrium, or strain‐free, values of die swell was demonstrated. The effect of long‐chain branch was to decrease elastic deformation. At constant shear stress, the melt elasticity of both high‐ and low‐density polyethylene was found to be essentially independent of temperature. Thus, at constant shear rate, elastic deformation decreased with increasing temperature, and it was demonstrated that this decrease could be quantitatively defined in terms of previously determined shear rate–temperature viscosity superposition shift factors.