bluuebunny/crossref_metadata_2025_split huggingface dataset:
The availability of hydroxyl groups in native and mercerized cotton celluloses
Authors: Bose J. L. , Roberts E. J. , Rowland S. P. 
Published: April 2003

AbstractThe accessibilities of the hydroxyl groups of the D‐glucopyranosyl units of slack mercerized grey yarn and of the same yarn restretched to its original length are compared with those of the original grey yarn, a purified printcloth, and a hydrocellulose. The study involved reactions of the celluloses with N,N‐diethylaziridinium chloride under conditions which ensure minimum conversion of the reagent by hydrolysis to 2‐hydroxyethyldiethylamine. Amylose was taken as a reference material in which the hydroxyl groups are assumed to be completely accessible. Selective accessibilities of the hydroxyl groups at C‐6 and C‐3 relative to those at C‐2 were determined with the same reagent by a method whose development has been described earlier. The results of this study are expressed as fractions of the hydroxyl groups at C‐2, C‐3, and C‐6 that are accessible to the reagent.
Hydrolyzed starch–polyacrylonitrile graft copolymers: Effect of structure on properties
Authors: Weaver M. O. , Gugliemelli L. A. , Doane W. M. , Russell C. R. 
Published: April 2003

AbstractThree starch–polyacrylonitrile (S–PAN) graft copolymers containing ratios of S:PAN of 1:1.90, 1:1.16, and 1:0.64 were prepared by graft polymerization of acrylonitrile onto gelatinized starch. A fourth graft, made from granular starch, had an S:PAN ratio of 1:2.16. These grafts were hydrolyzed in potassium hydroxide under various conditions to give a series of products with varying amounts of carboxylic acid and amide groups. Maximum conversion of nitrile to carboxyl was 65%. Aqueous dispersions of the hydrolyzed S–PAN's at pH 7–8.5 were viscous, and, in general, their viscosities reflected the amount of PAN add‐on, with the highest add‐on giving the highest viscosity. Plots of the η/C versus C show that hydrolyzed S–PAN's from gelatinized starch behave as normal polyelectrolytes on dilution to low concentration but that S–PAN from granular starch does not.
Ultrasonic degradation of the gel phase in impact polystyrenes
Authors: Wagner Eric R. , Cotter Robert J. 
Published: April 2003

AbstractThe rupture of the crosslinked rubber membranes in the gel particles of impact polystyrene by ultrasonic energy has been discovered to be a novel route for the semiquantitative analysis of the grafted and occluded polystyrene of the composite. Applying this new technique, the weight‐average molecular weight of the matrix, grafted, and occluded polystyrene of a bulk‐polymerized impact polystyrene was found to be approximately the same.
Cationic copolymerization of 1,3‐dioxolanes and 1,3‐dioxanes with 3,4‐dihydro‐2H‐pyran‐2‐methyl(3,4‐dihydro‐2H‐pyran‐2‐carboxylate). Nonfriable pyranyl foams
Authors: Papa Anthony J. , Proops William R. 
Published: April 2003

AbstractVarious substituted difunctional 1,3‐dioxolanes and 1,3‐dioxanes were copolymerized with a cyclic vinyl ether, 3,4‐dihydro‐2H‐pyran‐2‐methyl(3,4‐dihydro‐2H‐pyran‐2‐carboxylate), in the presence of boron trifluoride etherate catalyst. The copolymerizations proceeded rapidly and exothermally when initiated at room temperature and produced thermosetting resins. The copolymer products possess improved abrasion resistance and toughness as compared with homopolymer of the di(dihydropyranyl) monomer. As a practical consequence of these copolymerizations it is possible to prepare low‐density pyranyl rigid foams with improved friability resistance.
Tensile deformation of nylon 66 fibers at −196°C
Authors: Daniels B. K. 
Published: April 2003

AbstractNylon fibers tested in tension at −196°C show ductile strains up to 75%. The ductility is a complicated function of draw ratio, because decreasing work hardening with decreasing draw ratio leads to a point of instability where necking begins. The necks presumably initiate fracture, have the appearnce of cracks, and have been previously seen on fibers drawn in various organic liquids. Recovery experiments showed that molecular motions involved in low temperature deformation differ from those involved in ambient temperature deformation.
The effect of added salt on the flow of highly dilute solutions of poly(ethylene oxide) polymers
Authors: Little R. C. 
Published: April 2003

AbstractEarly transition, early turbulence, and drag reduction were detected in flowing solutions of high molecular weight poly(ethylene oxide) condensates. Progressive addition of salt (magnesium sulfate) increased the onset point characterizing deviations from Newtonian flow for 1 ppm Polyox Coagulant solutions and eliminated early transition in the 10 ppm WSR‐35 solutions. No further drag reduction was observed when the salt molarity reached the 0.65 level. In the Coagulant solutions the onset wall shear stress characterizing the flow deviation was an inverse function of the intrinsic viscosity of the polymer in the salt solution.
Vapor and gas permeability of asymmetric membranes
Authors: Peterlin A. 
Published: April 2003

AbstractThe membrane with continuously varying and pressure‐dependent local permeability P may show a dependence of transport property for gases and vapors on the direction of flow. Such an asymmetry occurs only if the deviation of local permeability from ideality varies from layer to layer. In mathematical formulation, this means that the local permeability is an irreducible function of location and pressure, i.e., not a product of a function of location and a function of pressure. The membrane permeability is higher if the side with greater deviation from ideal, i.e., constant permeability, is exposed to the higher pressure. For two simple cases the currents in both directions and their ratio at constant pressure difference were calculated. It turns out that the asymmetry of permeability increases with increasing deviation from ideality up to a maximum, after which the membrane tends to return to symmetry. An additional result of this investigation is the conclusion that Fick's law, i.e., the proportionality of the diffusion current to the negative concentration gradient is inapplicable not only to inhomogeneous membranes but also to homogeneous not ideal membranes.
NMR study of water adsorbed on methyl methacrylate‐grafted cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi 
Published: April 2003

AbstractGraft cellulose samples were prepared by three different initiation methods, and the widths of the NMR absorption spectra of samples were measured at various water contents. Samples prepared by both hydrogen peroxide and adsorbed ceric ion methods exhibited maximum widths of NMR absorption spectra at about 10% grafting, whereas the corresponding values for the sample prepared by the conventional ceric ion method were about 30%. Even a minimum value was found on the sample prepared by the latter method. The reason for such different water‐binding behaviors of samples is discussed from the viewpoint of difference in the composition of graft celluloses.
The graft copolymerization of styrene and lignin. II. Kraft softwood lignin
Authors: Phillips R. B. , Brown W. , Stannett V. T. 
Published: April 2003

AbstractThe radiation‐induced graft copolymerization of styrene and various kraft softwood lignins was studied. Expression of the results as the usual “per cent graft” was impossible, because grafting caused the lignin to become extractable in solvents for the styrene homopolymer. However, evaluation of the effects of various solvents on the degree of reaction was made through an indirect, and possibly more characteristic, measure. Grafting was least pronounced under conditions of low lignin accessibility (e.g., when less than 10% methanol was present), but increased with the addition of better lignin solvents or with higher methanol concentrations. The precipitating nature of the latter conditions was also found to contribute to an accelerated rate of grafting. Surprisingly, the graft copolymer was found to degrade at higher doses. Proof of grafting is offered in a fractionation scheme. Measurement of the molecular weight of the polystyrene separated from the lignin backbone allows the estimation of approximately one polystyrene graft per lignin molecule in benzene‐extractable copolymers. Two glass transition temperatures could be detected in several fractionated copolymers.
Mechanical and relaxation properties of polystyrene molded at high pressures
Authors: Dale W. C. , Rogers C. E. 
Published: April 2003

AbstractAtactic polystyrene glasses were molded at high pressures by cooling the polymer melt at pressures up to 5000 atm. Changes found in the properties of the samples included: a lower mechanical damping factor at temperatures from 50°K to 300°K; a higher compressive elastic modulus; a maximum in compressive yield stress at a molding pressure around 1000 atm; faster relaxation at yield; appearance of an exothermic dilational relaxation below Tg when the samples were heated; and faster relaxation in methyl ethyl ketone vapor. The observed behavior is interpreted in terms of a model based on pressure‐induced heterogeneities in local order. The initial effect of increased molding pressure is to produce a more compact polymer which has less segmental mobility and more extensive interchain forces. Above molding pressures of about 1000 atm, a second effect develops due to the apparent formation of localized conformations which are stable under the high‐pressure vitrification conditions, but not at room conditions. The spontaneous decay of these high‐energy regions leads to subsequent formation of microvoid defects and more rapid structural relaxation effects. The existence of an optimum molding pressure somewhat below 1000 atm is indicated for polystyrene.
Polyelectrolyte effect and conformational transition in a restricted polyacid structure
Authors: Healy E. M. , Ramsley A. O. , Natsios B. A. 
Published: April 2003

AbstractIn a polyacid consisting of polyacrylic acid attached to a polyamide matrix, marked effects in equilibrium acid–base characteristics are observed, attributable to a hindered polyelectrolyte structure. In the presence of neutral electrolyte, the very high values found for pKa drop sharply. A break in the Henderson‐Hasselbalch curve indicates a conformational transition at α = 0.55 which is deferred to 0.95 by the presence of neutral electrolyte.
The production of rubber‐modified polystyrene. Some criteria influencing the selection and design of the agitator system
Authors: Freeguard G. F. , Karmarkar M. 
Published: April 2003

AbstractThe importance of selecting the most suitable form of agitation for the prepolymerization step in the production of rubber‐modified polystyrene by a bulk polymerization procedure is related to the non‐Newtonian behavior of the polymerizing system and to the existence of a minimum shear rate requirement. The procedure for the design and calibration of a small‐scale reactor system is described which is shown to produce an adequate phase inversion of the prepolymer and from which data can be evaluated for any change in scale of the operation. Structural patterns in the final polymer are linked with average shear levels in the reactor.
The effect of solvent traces on the ultraviolet degradation of poly(vinyl chloride)
Authors: Kamal M. R. , El‐Kaissy M. M. , Avedesian M. M. 
Published: April 2003

AbstractThe ultraviolet degradation of poly(vinyl chloride) films was studied in a photoreactor which supplied energy near 3000 Å. It was noted that the rate of degradation and color development was increased when the level of residual solvent in the cast films was increased. Two solvents were employed in the study: tetrahydrofuran and dichloroethane. The amount of residual solvent was correlated with the height of a characteristic peak at 2800 Å for tetrahydrofuran and 1900 Å for dichloroethane. Films which had very small traces of solvent showed excellent resistance to ultraviolet degradation, even in the absence of ultraviolet stabilizers. The analysis of solubility data showed that chain scission was controlling in the early stages of exposure, while crosslinking was controlling at later stages. As a result, it was not possible to apply Charlesby's treatment of radiation‐induced degradation. Comparison with the results obtained by other workers for degradation at 2537 Å showed that degradation at this wavelength was much faster than degradation at 3000 Å. Furthermore, degradation at 2537 Å appeared to be controlled by crosslinking at all stages of exposure.
Action of alkali metal hydroxides on cotton
Authors: Zeronian S. H. , Cabradilla K. E. 
Published: April 2003

AbstractThe swelling of cotton increased continuously as the concentration of LiOH solution was raised progressively to saturation. In contrast, the swelling of cotton treated with NaOH or KOH leveled off at higher concentrations after increasing initially. The maximum swelling achieved with NaOH was higher than that obtained with LiOH, which was higher than that given by KOH. Accessibility of cotton treated with LiOH solutions, as indicated by sorption ratios, was lower than that of cotton treated with NaOH or KOH solutions of similar concentrations. The level‐off degree of polymerization (LODP) of cotton treated with similar concentrations of alkali decreased in the order LiOH, NaOH, KOH. The reactivity, as indicated by acetylation, of cotton treated with alkali metal hydroxides, washed with water, and never dried was measured. At concentrations between 5.5.N and 8.2N, the rate of increase of reactivity was relatively low for cotton treated with NaOH, and no increase was observed for cotton treated with KOH. The reactivity of LiOH‐treated cotton continued to increase sharply up to treatment with a saturated solution of the alkali. A limited number of observations were also made on cotton treated with CsOH and RbOH. Accessibility, reactivity, extent of swelling, and LODP values, together with x‐ray data, are discussed in relation to the fine structure of the alkali‐treated fiber.
The glass transition temperature of a filled binder by nuclear magnetic resonance and thermal mechanical analysis
Authors: Price E. , French D. M. , Tompa A. S. 
Published: April 2003

AbstractThe glass transition temperatures of a binder and filled binder were determined by wide line proton nuclear magnetic resonance and by thermal mechanical analysis. The NMR study indicated only one transition temperature for the binder and three transition temperatures for the filled binder. TMA data gave two transition temperatures each for the binder and for the filled binder. These transition temperatures in the filled binder were interpreted as representing two phases: one for the filler‐oriented binder and one for the bulk phase. A comparison of the transition temperatures of the binder and filled binder indicates that the transition temperature of the former is raised by the presence of the filler. It was also found that the presence of water lowered the transition temperature of the filled binder used in this work.
Photochemical degradation of poly(ethylene terephthalate). II. Effect of wavelength and environment on the decomposition process
Authors: Day M. , Wiles D. M. 
Published: April 2003

AbstractPoly(ethylene terephthalate) has been irradiated with UV light of different wavelengths and in various atmospheres. The extent of degradation was monitored by measuring the tensile strength, molecular weight, carboxylic acid endgroups, and fluorescence emission of the polymer. The importance of wavelengths <315 nm in causing deterioration was demonstrated to be mainly due to strong surface absorption which results in surface crazing and ultimate fracture under stress. Irradiation in nitrogen and under vacuum were found to give similar results, but with oxygen present in the system several significant differences were observed. In nonoxidative irradiations, crosslinking and discoloration of the polymer occurred. Under oxidative conditions, chain scissions and fluorescent material build‐up resulted, whereas no crosslinking and only slight discoloration was observed. The possibility of a photo‐oxidation reaction has thus been suggested, involving hydroperoxide formation, to explain the discrepancy in results obtained for the two types of environments.
Photochemical degradation of poly(ethylene terephthalate). III. Determination of decomposition products and reaction mechanism
Authors: Day M. , Wiles D. M. 
Published: April 2003

AbstractThe vacuum photolysis and air photo‐oxidation of poly(ethylene terephthalate) were studied using light in the wavelength ranges of 225–420 nm and 300–420 nm. The volatile photodegradation products were determined by mass‐spectrometric and gas‐chromatographic analysis; CO and CO2 were found to be the predominant products. In addition, the rates of formation of carboxylic acid endgroups and the net weight losses of the film samples were determined as a function of irradiation time. Quantum yields for the initial rates of formation of CO and CO2 and of COOH within the film were calculated. On the basis of the results obtained, in this and the preceding papers in this series, reaction mechanisms have been proposed for the photochemical degradation of the polymer. The production of CO and COOH in both vacuum and air have been attributed mainly to a Norrish type I cleavage and a Norrish type II photorearrangement, respectively. It has also been concluded that, in the presence of air, an oxidative reaction sequence occurs whereby alkyl radicals produced on photolysis react with oxygen to form ROO. radicals. These subsequently react further to produce CO2 as the main volatile product of photooxidation.
Changes in porosity of treated lint cotton fibers. I. Purification and swelling treatments
Authors: Porter Blanche R. , Rollins Mary L. 
Published: April 2003

AbstractChanges in the internal morphology of lint cotton fibers during purification and swelling treatments were investigated by measurement of nitrogen adsorption at liquid nitrogen temperature. Surface areas and pore size distributions were calculated from the adsorption isotherms and compared with findings from measurements of changes in crystallinity and in fibrillar aggregation as shown by electron micrographs. The adsorption measurements were made on fibers which were either preswollen in water or taken from the rinse water after treatment and solvent exchanged through methanol and n‐pentane to helium. The large changes found in surface area, pore size distribution, and fibrillar aggregation were accompanied by changes in crystal structure in fibers treated with 5.0M sodium hydroxide. Large changes following treatment with phosphoric acid occurred in pore structure and fibrillar aggregation without concomitant change in crystallinity.
Changes in porosity of treated lint cotton fibers. II. Treatments for chemically modifying cotton
Authors: Porter Blanche R. , Rollins Mary L. 
Published: April 2003

AbstractChanges in the internal morphology of chemically modified lint cotton fibers were investigated by measurement of nitrogen adsorption at liquid nitrogen temperature. Surface areas and pore size distributions were calculated from the adsorption isotherms and compared with findings from measurements of changes in crystallinity and of fibrillar aggregation as shown by electron micrographs. Fibers were either preswollen in water or taken from the rinse water and solvent exchanged through methanol and n‐pentane to helium before adsorption measurements were made. Unless reacted in the presence of water, the wrinkle resistance treatments studied caused losses in surface area of 55% or greater. Changes in surface area and porosity of cottons reacted with monofunctional reagents designed to give protective and other types of finishes were dependent on the type of reaction used.
Pyrolysis and combustion of cellulose. III. Mechanistic basis for the synergism involving organic phosphates and nitrogenous bases
Authors: Hendrix James E. , Drake George L. , Barker Robert H. 
Published: April 2003

AbstractThe flame retardation mechanisms for cellulose treated with systems based on aromatic phosphates and phosphoramides have been investigated through pyrolysis studies on cellulose and related model compounds. Pyrolysis of cellulose treated with phosphates or phosphoramides proceeds through formation of cellulose phosphate or phosphoramide esters, followed by subsequent ester pyrolysis to yield a dehydrated cellulose char. Formation of phosphoramides during pyrolysis of flame retardants containing phosphorus and nitrogen constitutes a possible basis for reported phosphorus‐nitrogen synergistic effects observed in commercial flame retardants. Efficiency of ester formation is higher, and subsequent pyrolysis is lower for phosphoramides than for phosphate esters. The build‐up of a thermally stable crosslinked matrix in the residue occurs on pyrolysis of cellulose treated with phosphoramides. Such crosslinking seems to be effective in enhancing flame retardation.
Relationship in polypropylene melt between its linear viscoelasticity and its steady capillary flow properties
Authors: Fujiyama Mitsuyoshi , Awaya Hiroshi 
Published: April 2003

AbstractIt is the object of the present study to obtain clear knowledge of the relations in the polypropylene melt between its linear viscoelasticity and its nonlinear steady capillary flow, paying particular attention to the elastic properties in its capillary flow. By representing the linear viscoelasticity numerically with zero‐shear viscosity, η0, and steady‐state compliance, J, evaluation has been made of the properties concerning the elasticity of polymer melt in the capillary flow, such as non‐Newtonianity, the entrance pressure loss, the end correction, the Barus effect, and the melt fracture. The steady flow viscosity η, the entrance pressure loss P0, the critical shear stress, τc, and the critical shear rate $\dot \gamma _c$ at which melt fracture begins to occur are subject to η0 as follows:

From the well‐known relationship between η and the weight‐average molecular weight M̄w, these quantities are governed by M̄w. Meanwhile, for such quantities as structural viscosity index N, end correction coefficient ν, and elastic pressure loss ratio P0/P, following correlations hold:

As η0 and J are respectively determined mainly by M̄w and the molecular weight distribution MWD, these quantities are governed by both M̄w and MWD. Physical meanings of η0·J and η02 · J are, respectively, mean relaxation time and a measure of stored energy in steady flow. The Barus effect has a positive correlation to J, ν, and P0/P. (The symbol ∝ employed here means positive correlation.)
Optical detection of thermal transitions in high polymers
Authors: Kovacs A. J. , Hobbs S. Y. 
Published: April 2003

AbstractThis report describes a series of recent experiments in which various thermal transitions including stress relaxations and glass transitions in high polymers were characterized by observing birefringence changes during heating and cooling. An automatic recording device employing a hot stage, polarizing microscope, photocell, and chart recorder was employed in these investigations. A general discussion of the utility and advantages of the technique of thermo‐optical analysis (TOA) as well as its deficiencies is presented. Characteristic birefringence–temperature profiles of a number of amorphous and semicrystalline polymers are included.
A generalized method for correcting instrument spreading in gel permeation chromatography
Authors: Chang Kun S. , Huang Robert Y. 
Published: April 2003

AbstractA general method of chromatogram correction for skewed instrument spreading in gel permeation chromatography is presented. The correction method is so general that there is no restriction on the shape of the spreading function. It admits nonsymmetric, non‐Gaussian as well as nonconvolution type. Aspects of solution techniques are discussed and an illustrative example is given to elucidate the method.