bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical characterization of cellulose xanthate in solution
Authors: Tait C. W. , Vetter R. J. , Swanson J. M. , Debye P. 
Published: April 2003

AbstractThe intrinsic viscosity of cellulose xanthate solutions was studied as a function of the electrolyte content of the solvent, and found to decrease sharply with increase in electrolyte concentration. All electrolytes tested except sodium and lithium hydroxides produced essentially the same reduction in intrinsic viscosity for solutions of equivalent ionic strenghts, indicating that the effect was largely one of interaction between the solvent ions and the charged xanthate groups. Hydroxides induced a greater viscosity reduction. The reason for this was not fully resolved; however, indications were obtained that the hydroxides, in addition to behaving as electrolytes toward the charged xanthate groups, also interact with the hydroxyl groups on the parent cellulose chain.Light scattering measurements, as well as data on the variation of the intrinsic viscosity with molecular weight in various solvents, showed that the change in intrinsic viscosity with electrolyte concentration could be accounted for by a change in configuration, or degree of coiling of the molecule. Calculations indicated that in pure water cellulose xanthate should approach a rigid rod configuration whereas in 6% caustic coiling occurs and the molecule resembles more a random configuration.
Solutions of polyelectrolytes and mechanochemical systems
Authors: Katchalsky A. 
Published: April 2003

AbstractThe behavior of polyelectrolyte molecules in aqueous solution has been discussed. It has been shown that the pronounced increased in viscosity of polymeric acids upon ionization is due to the change of shape of the molecule due to electrostatic repulsive forces. Nonionized polymeric acids assume the form of highly hypercoiled rigid spheres obeying Einstein's viscosity law, the hypercoiled form being presumably due to strong intermolecular hydrogen bonding and van der Waals' interactions. The polymeric molecules open up with increasing ionization, and assume the form of freely linked threads, obeying Staudinger's law, at about 10% ionization. At high degrees of ionization, they stretch to rod‐like filaments, with the viscosity increasing as the square of the molecular weight. The shape of the molecules is also dependent on the concentration of the solution and on the amount of foreign ions present. An excess of the latter annihilates the electrostatic field and reduces the viscosity to that of normal random coils. Polyampholytes of the type of copolymers of methacrylic acid and vinylpyridine show the expected behavior: the viscosity is at a minimum at the isoelectric point and increases in both the acidic and alkaline regions with the increase in free charge.The field energy of polyelectrolyte molecules has been determined thermodynamically by means of the potentionmetric titration. It has been shown to be dependent upon the molecular weight, the concentration of the polymer, and the ionic strength. The charge of the field energy per ionized group has been found to be independent of the molecular weight.The electrostatic field energy has been calculated theoretically from statistical and electrostatic considerations and an approximated formula has been arrived at by using a simplified model. The calculated field energies have been compared with those derived from potentiometric titration and found to be in good agreement with each other.The deviations from the theory, the particular shape of the viscosity versus degree of ionization, and field energy versus ionization curves, have been attributed mainly to the existence of contractile van der Waals' forces, operative between the segments of the polymeric molecules. These forces act in addition to the usual rubberlike configurational elasticity. An attempt has been made to explain these effects on a quantitative basis.Mechanochemical systems capable of transforming chemical energy of ionization into mechanical energy of stretch have also been described. These systems, typified by cross‐linked gels and fiber gels of polymeric electrolytes, can be made to work in isothermal cycles in a manner reminiscent of the physicochemical mechanism of the muscle. A cycle has been analyzed in which a system is made to work between two pH values (corresponding to chemical potentials), and two degrees of ionization, under the influence of an exterior force.
Thermodynamics and mechanics of filler reinforcement
Authors: Rehner John 
Published: April 2003

AbstractFollowing a brief review of some earlier theories of filler reinforcement that were based, at least partly, on thermodynamic treatments, a reinforcement equation is derived by a combination of thermodynamics and the elasticity theory of large strains. It consists of an elastic energy term and a surface energy term, and is given by:

In it, the “reinforcement energy,” R.E., is defined as the energy of the filler‐rubber mixture less that of the separate components. This is related to a fractional heat term (p) arising from the “expansion” of the rubber due to filler incorporation, the Young's modulus (E) of the rubber, the number of particles (n) of filler (considered as existing initially in an aggregate), the ultimate particle diameter (d), the volume of rubber (V1), the total energy of immersion per unit surface area (Γ) of the filler in the rubber, and the mean cohesion or aggregation energy per particle (δ) between the particles in the original aggregate.The significance of R.E. in terms of actual reinforcement is discussed; R.E. is regarded as negative measure of reinforcement. Estimates are made of the magnitudes of the two energy terms and of the surface energies Γ and δ. These indicate that in mixtures containing very active fillers (such as carbon blacks in natural rubber), Γ is of the order of 100 ergs per sq. cm. and the surface energy term is dominant. A crude estimate indicates that δ is much less than Γπd2 for very active fillers, that these quantities may be of the same order of magnitude for less active fillers, and that δ may be larger than Γπd2 for inert fillers. In the last two cases, the surface energy term loses much or all of its dominant character.Predictions from the reinforcement equation are examined in the light of available experimental results, and some apparent discrepancies are discussed. Expressions are given for corrections that need to be applied to the equation when particle dispersion is incomplete, or when the latter is a function of the filler concentration.
The counterion distribution in solutions of rod‐shaped polyelectrolytes
Authors: Alfrey Turner , Berg Paul W. , Morawetz Herbert 
Published: April 2003

AbstractFor solutions containing rod‐shaped polyelectrolytes and their counterions only, the Poisson‐Boltzmann equation can be solved explicity without the usual assumption of the Deybe‐Hückel theory. At charge densities corresponding to half‐neutralized polyacrylic acid a large proportion of monovalent counterions is located close to the polyion even in solutions as dilute as 1/800 base molar.
Catalytic conversion of a diene into deeply colored polymers
Authors: Eisler B. , Farnsworth S. D. , Kendrick E. , Schnurmann R. , Wassermann A. 
Published: April 2003

AbstractCyclopentadiene can be catalytically converted into a deep red polycyclopentadienetrichloroacetic acid adduct (I). Oxidation and hydrogenation experiments show that each repeating unit of (I) contains one double bond. Other observations, including spectroscopic and electrochemical measurements indicate that these double bonds are conjugated, and that this polymerization involves the migration of hydrogen atoms. The kinetics of the formation of (I) are investigated and some results of these measurements, together with those pertaining to the alkaline hydrolysis of (I), make it probable that the initiation step is in acid‐catalyzed esterification of the diene and that the final polymer is an ester. Colloid chemical properties of (I) are described.
Etude thermocinétique de l'adsorption. Cas des corps solubles et des substances macromoléculaires
Authors: Calvet Edouard 
Published: April 2003

AbstractL'étude thermocinètique de l'adsorption et celle de la chaleur dégagée en fonction de la masse du corps adsorbé par unité de masse de l'adsorbant réalisées au microcalorimètre (spécialement adapté à la mesure des phénomènes lents) nous parait présenter un grand intérêt: pour les corps insolubles ces études permettent l'évaluation des surfaces des poudres, la mesure approximative de la vitesse d'expansion des films, l'étude de la fraction activée des surfaces; pour les corps solubles elles permettent de mettre en évidence le phénomène très général de l'adsorption qui précède la dissolution et d'interpréter le mécanisme de la dissolution; pour les substances macromoléculaires elles permettent de classer les solvants ou gélatinisants suivant leur activité, d'étudier le gonflement, les complexes de solvatation, etc. Tout cela démontre le nécessité d'organiser des Centres bien équipés de microcalorométrie des phénomènes lents.
Method of colloid titration (a new titration between polymer ions)
Authors: Terayama Hiroshi 
Published: April 2003

AbstractA general discussion about the method of colloid titrations is given in this report. A new titration method is based on the stoichiometric combination of positive and negative colloid ions. The end point is decided by indicators (known as metachromatic coloring matters) like toluidine blue. The standard colloid reagents are P.V.S.‐K (potassium salt of polyvinyl alcohol sulfate) and Macramin (N‐polymethylated chitosan derivatives). The typical operations of this method are described briefly: the direct, indirect, and differential titration methods. The colloid titration curve is somewhat different from the acid‐base titration curve obtained potentiometrically, but it is characteristic and reproducible under definite conditions and so it is useful in quantitative and qualitative analysis. This titration may be carried out even under extraordinary dilute conditions (5 × 10−4 N) and the entire process is quite similar to the usual acid‐alkali titration. The precision is below ±ca. 5% if the method is carefully followed.
Redox recipes. VI. Redox systems containing potassium chromate as oxidizing constituent
Authors: Kolthoff I. M. , Meehan E. J. 
Published: April 2003

AbstractThe emulsion copolymerization of butadiene (75)‐styrene (25) is initiated by redox systems containing potassium chromate as oxidizing constituent. In alkaline (soap) recipes, the system chromate‐arsenic trioxide is especially effective, giving a rate of conversion of about 20% per hour at 30°C. with 5 parts of potassium myristate (0.3 part of potassium chromate and 0.07 part of arsenic trioxide per 100 parts of monomers). Other fatty acid soaps or sodium alkyl sulfate may be used instead of myristate, although no other soap or emulsifier tested gives a rate as large as does myristate. Mercaptan has a slight accelerating effect but the presence of mercaptan is not necessary for initiation of polymerization. The use of arsenic trisulfide as reducing agent gives rise to rapid polymerization but the rates vary with different suspensions of arsenic trisulfide. Potassium antimonyl tartrate also may be used in combination with chromate to give rapid polymerization at 40°C. with fatty acid soap. Tin(II) is much less effective than either arsenic(III) or antimony(III). Inorganic reducing agents which in combination with chromate are inefficient in initiating the copolymerization include iron(II), thallium(I), dithionite, hydrazine, hydroxylamine, and sulfide.
Redox recipes. VIII. A recipe with ferric versenate, sodium sulfide and hydroperoxide as activating system (veroxasulfide recipe)
Authors: Kolthoff I. M. , Meehan E. J. 
Published: April 2003

AbstractA new recipe called the Veroxasulfide Recipe is described for the polymerization of butadiene (75)‐styrene (25). The initiating system is composed of ferric versenate, sodium sulfide, and a hydroperoxide. With K‐fatty acid soap as emulsifier, the use of 0.00728 part of ferric nitrate nonahydrate (corresponding to 10−4 M ferric iron in the aqueous phase), 10−4 M versene, 0.02 part of sodium sulfide, and 0.1 part of Diox D, the following conversions are found at 5°C.:

Time, hrs.
1
2
4
8
12

Conversion, %
8
16
32
66
85

The optimum amount of sodium sulfide is 0.02 part (equivalent to 0.062 part of the nonahydrate) but the rate does not depend critically on the amount. The optimum rate is found with approximately 0.00025 M ferric versenate (8.3% in 8 hours at 5°C.) and the rate may be adjusted conveniently by adjustment of the amount of ferric versenate. The presence of a considerable excess of versene over ferric iron does not affect the rate. With less versene than the amount equimolar to the amount of ferric iron the rate corresponds approximately to that observed with the corresponding amount of ferric versenate; that is, the rate is determined by the amount of ferric versenate rather than by the total amount of ferric iron. Latex of normal fluidity is obtained with charges containing 0.5 part or more of potassium chloride; without added electrolyte thick latex subject to precoagulation is obtained. Satisfactory rates are found with mixtures of Dresinate 214 and K‐fatty acid soap. Mercaptan is not needed for initiation; the same rate is found with n‐dodecyl mercaptan, with sulfole mercaptan, and without mercaptan. The kind of agitation has no or slight effect on the rate. Added oxygen has only a slight effect which is largely eliminated by the addition of sodium dithionite. A recipe is given which at −5°C. yields 70–75% conversion in 12 hours. Polymerization using the Veroxasulfide recipe at 25°C. may provide a sensitive test for traces of iron in ingredients used in polymerization recipes, since with 2 × 10−6 M ferric versenate (corresponding to 0.1 p.p.m. of ferric iron per liter of aqueous phase), 32% conversion is reached in 11 hours, whereas in the absence of iron 3% conversion is reached in the same time.
Étude optique de la morphologie des particules de thymonucléate de sodium en fonction du pH et en solution diluée
Authors: Horn P. , Leray J. , Pouyet J. , Sadron Ch. 
Published: April 2003

AbstractCertaines propriétés physiques des solutions de thymonucléte sodique ont été déterminées en solution neutre et après ajustement au pH 3.8 au moyen d'acide chlorhydrique 0.01 M. On a trouvé que la viscosité intrinsèque au gradient zéro est 5700 en solution neutre et 3900 au pH 3.8. De plus, cette dernière viscosité reste inchangée après reneutralisation de la solution avec de la soude 0.01 M. La diffusion de la lumière montre que le poids moléculaire est le même dans les deux cas, et indique que les particules sont plus dissymétriques en solution neutre. Des mesures de biréfringences d'‐ écoulement et d'angles d'extinction permettent de confirmer cette interprétation.
Modèle statistique des grosses molécules à chaînes courtes. V. Diffusion de la lumière
Authors: Peterlin Anton 
Published: April 2003

AbstractLes fonctions de diffusion P(ϑ) des molécules linéaires, présentant un degré de rigidité variable et caractérisées par une logueur permanente a (comme définies par Kratky et Porod) ont été calculées; a est défini comme étant la projection d'une chaîne infiniment longue dans la direction du premier segment moléculaire. Les résultats sont obtenus sous la forme de développements en série valables pour des degrés de flexibilité moyens à élevés. On montre que les fonctions de diffusion ainsi obtenues sont comprises entre celles correspondant à un bâtonnet rigide et à une pelote statistique. En outre, les auteurs indiquent une méthode qui permet d'obtenir les paramêtres moléculaires a, la longueur L et le diamètre de la spire R aux dépens des résultats expérimentaux.
Diffusion of organic molecules through wood
Authors: Narayanamurti D. , Kumar Vidya Bhushan 
Published: April 2003

AbstractThe diffusion of alcohols, glycerol, phenol, formic, acetic and butyric acids through four species of Indian timbers in the water‐saturated condition has been studied and the results reported. In contrast to several inorganic ions, Fick's law is obeyed by the organic molecules in the concentrations studied. As is to be expected, the diffusion in the axial direction is several times that in the other directions. The speed of diffusion decreases rapidly with the molecular weight of the substance and the density of the wood. While in the case of the alcohols the logarithm of the diffusion constant varies as the molecular weight with the acids the diffusion constant is proportional to the molecular weight.
A new phenomenon in flow birefringence of solutions of macromolecular substances
Authors: Arlman E. J. , Boog W. , Coumou D. J. 
Published: April 2003

AbstractMeasurements on flow birefringence of solutions of polyvinyl chloride in cyclohexanone revealed that the angle of orientation increases with decreasing concentration of the solution. That this surprising effect was not due to constructional or experimental errors was demonstrated by results obtained with polystyrene, which were in agreement with literature data.
Infrared spectrophotometric studies on polyethylene. I. Structure
Authors: Rugg Frank M. , Smith Joseph J. , Wartman Lloyd H. 
Published: April 2003

AbstractA series of polyethylene resins made by making progressive changes in temperature, pressure, and catalyst content has been studied by infrared absorption spectroscopy. From the methyl content and the number‐averages molecular weight of each resin, it was found that as molecular weight increases degree of branching decreases. Also revealed was the fact that each of the three types of double bond groups present, i. e., RHCCH2, RHCCHR, and RRCCH2, decreases in concentration with increasing molecular weight. Using polarized radiation, high resolution grating spectra were obtained on polyethylene films which had been highly oriented by cold drawing 500%. The results show that the CH3 terminated branches are not predominantly oriented either parallel or perpendicular to the direction of stretch. It is the authors' view that the chain branches vary in length with a considerable fraction short enough to be essentially at right angles to the long chain axis while others are sufficiently long to be parallel to the long chain axis in stretched polyethylene. When a stretched polyethylene film is heat relaxed (110–115°C.), its spectra using polarized radiation reveal the presence of crystallites in which the long carbon‐to‐carbon chain axes are predominantly oriented at right angles to the direction of stretch.
Refractometric determination of second order transition temperatures in polymers. VI. Effect of molecular weight on the transition temperature of polyvinyl acetate
Authors: Wiley Richard. H. , Brauer G. M. 
Published: April 2003

AbstractThe transition temperatures (TG) of unfractionated vinyl acetate polymers increase from 17° to 26° as the molecular weight increases from 14,000 to 104,000 and from 26° to 28° as the molecular weight increases from 104,000 to 1,120,000. The minimum molecular weight above which increase in molecular weight does not appreciably change TG is about 100,000. TG increases linearly with the reciprocal of the square root of the molecular weight.
Application of the steady state method to benzoyl peroxide initiated polymerization of styrene
Authors: Horikx M. M. , Hermans J. J. 
Published: April 2003

AbstractThe steady state method is applied to the benzoyl peroxide initiated polymerization of styrene in toluene at 80°C. The reaction mixture is kept homogeneous by stirring. A theoretical discussion shows that the time needed to reach the steady state concentrations with an accuracy of 1% or better is about seven times the average time which the mixture spends in the reaction vessel; this is confirmed by experiment. The experimental results show that the rate of polymerization can be represented by the formula:

where m is the monomer concentration, while k and β are constants. It is found that β = 1.19 liter/mole. The apparent order of the reaction, with respect to monomer, increases from 1.18 when m = 1.8 mole/liter to 1.36 when m = 0.4 mole/liter. An analysis of the limits of experimental error indicates that in the conventional method this change in apparent reaction order would have been of the same order of magnitude as the experimental error. The accuracy of the steady state method, however, is sufficient to establish this change unambiguously. Numerous data from the literature concerning the polymerization of styrene and other monomers are discussed, and are found to be in good agreement with the conclusions reached in the present work. Explanations are offered for a number of discrepancies found in the literature.
Copolymerization characteristics of some vinylnaphthalenes and vinylphenanthrenes
Authors: Price Charles C. , Halpern Benjamin D. , Voong Sing‐Tuh 
Published: April 2003

Abstractβ‐Vinylnaphthalene, 6‐chloro‐2‐vinylnaphthalene, 4‐chloro‐1‐vinylphenanthrene, and 2‐ and 3‐vinylphenanthrenes have been copolymerized with styrene, methyl methacrylate and methyl acrylate. All copolymerize well to give products generally softening at higher temperatures than polystyrene of its copolymers. Analysis of the relative reactivities in copolymerization indicates that, with the exception of the single α‐vinylnaphthalene derivative, these monomers are more reactive in copolymerization than styrene. This is in agreement with expectations based on the greater possibilities for resonance stabilization of an adjacent free radical by the naphthalene and phenanthrene nuclei.
Studies on aldehyde‐protein interactions. I. Reaction of amino acids with lower aldehydes
Authors: Robert L. , Penaranda F. S. 
Published: April 2003

AbstractThe kinetics of reaction between amino acids and lower aldehydes (acetaldehyde, propylaldehyde) was followed by the Van Slyke technique and a quantitative chromatographic method. In a narrow range of pH (pH 6–7), the reaction was found to be bimolecular. Graphically computed bimolecular kinetic constants are presented for a certain number of amino acids reacting with acetaldehyde. Under certain conditions (for instance, tryptophane in acetic acid solution with acetaldehyde) the reaction rate was slowed down to trimolecular. At some acid or alkaline pH values the exact order of the reaction could not be determined (it was not of the first, second, or third order). Except for tryptophane, which reacted more rapidly in acid media, the amine‐aldehyde combination rate was accelerated by rising pH. The combination rate of histidine is directly proportional to the acetaldehyde concentration, the proportionality factor being unchanged with increasing the pH from 3.00 to 6.20. In some cases (for example, propylaldehyde with lysine) the amino nitrogen content reached a minimum after 10–20 minutes, and then rose to attain even the initial value. Specific viscosity did not change (tryptophane), or else decreased (lysine, arginine, histidine) during the acetaldehyde‐amino acid reaction. In acetaldehyde‐NaOH or acetaldehyde‐morpholine mixtures the viscosity was unaltered even when the solution became rapidly turbid and aldehyde‐resin precipitated. It was possible to separate the reaction products obtained during the formation of aldehyde‐resin and aldehyde‐amino acid interaction by the method of paper electrophoresis. The fluorescent patterns were characteristic for each amino acid. Most of the amino acids showed 3–6 spots of different fluorescent color. This rendered probable the hypothesis that the same aldehyde condensation products are formed in amino acidaldehyde mixtures as in alkali‐acetaldehyde solution.