bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and properties of esters of polyorthotitanic acid
Authors: Boyd T. 
Published: April 2003

AbstractIn studies of the synthesis of alkyl titanates from anhydrous butyl alcohol and titanium tetrachloride employing ammonia or an amine to neutralize the hydrogen chloride formed, Speer has reported uniformly unsuccessful results in repeating the examples of Nelles' patents on this process. Kraitzer, Winter, and others followed Nelles' process successfully employing a large excess of anhydrous butyl alcohol. Repetition of Nelles' patent examples is awkward because the ammonium chloride formed in the reaction produces a thick slurry too inconvenient to handle. However, if this slurry was diluted or extracted with an anhydrous hydrocarbon solvent,i.e.,toluene, yields of 80% were achieved. Furthermore, since it is difficult to obtain rigorously anhydrous alcohols, it is more convenient to carry out the synthesis of alkyl titanates using an inert anhydrous solvent,i.e.,toluene or carbon tetrachloride, as a reaction medium along with the stoichiometric quantity of alcohol instead of using a large excess of the alcohol as the reaction medium. The formation of nonvolatile residues was avoided.If the proper quantity of water dissolved in a low‐boiling alcohol is added slowly with stirring to a solution of the corresponding ester of orthotitanic acid, it is possible to obtain esters of polyorthotitanic acid of controlled average molecular weight. If less than 1 mole of water per mole of orthotitanate esters is employed, the amount of cross‐linked polymer derived is vanishingly little. When the butylorthotitanate was treated with 1.5–2.25 moles of water per mole of titanium, 1.4–1.5 moles of water were consumed per mole of titanium. Water was recovered from the system. Water in excess of 2.25‐3 moles of water per mole of titanium caused complete conversion of butylorthotitanate to titanium dioxide. The polyorthotitanates were soluble in benzene, toluene, and butyl alcohol. The uncross‐linked polymers vary in appearance from very viscous liquids to waxy solids. The polyorthotitanates enter into ester interchange reactions with alcohols in which one to all of the lower boiling alkyl groups may be replaced by the higher one. Long‐chain organic acids react with the alkyl polyorthotitanates or the alkyl titanates to replace one to all of the alkyl groups.
Light scattering studies on some muscle proteins
Authors: Steiner Robert Frank , Laki Koloman , Spicer Samuel 
Published: April 2003

AbstractA light scattering investigation of actin and actomyosin gives the following information. The weight average molecular weight of 80,000 is found for G‐actin. The average molecular weight and length of F‐actin decrease upon increasing concentration of electrolyte, the effect being especially pronounced in the case of KI. The average molecular weight and length of F‐actin decrease with increasing of pH of polymerization. The average length and molecular weight of F‐actomyosin increase with decreasing ionic strength. The average length and molecular weight of F‐actomyosin decrease with decreasing size of the F‐actin component.
A new molecular weight distribution technique for polystyrene. I. Theory
Authors: Boyer Raymond F. 
Published: April 2003

AbstractThis paper is concerned with the description of a simple technique for determining the molecular weight distribution curve of polystyrene (and presumably any other soluble polymer consisting of a polymer‐homologous series). The general theory of the method as well as preliminary experimental results will be covered. The method is characterized by: (1) simple technique and equipment; (2) no need to isolate and measure fractions; and (3) a general basis in thermodynamic theory of polymer solutions, although a double calibration is needed to determine numerical parameters. The method consists in adding increasing quantities of nonsolvent to a dilute solution of polystyrene in a good solvent and observing the cumulative volume of precipitate as a function of nonsolvent content. The settled gel must re‐equilibrate (hence deswell) with the new solvent after each alcohol addition. The swelling ratio, S (cc. of swollen gel per gram of dry polymer), of the swollen precipitate is approximately independent of the molecular weight and depends mainly on the volume percent of nonsolvent, γ according to

where α, σ, and s are constants. Likewise, the molecular weight, M, of the species precipitated at any nonsolvent content is given by the Schulz precipitability equation:

where α, β, and m are constants. For the system polystyrene–benzene–methanol, we find s = 4/3 while Schulz had already noted that m = 2/3. Elimination of γ and α leads to the prediction of a linear relation between M and S2. A two‐fold calibration to obtain the constants in equations (1) and (2) is necessary to convert the observed data to an absolute cumulative weight versus molecular weight curve. However, even the simple plot of cc. of precipitate versus percent nonsolvent is informative. The relationship of these results to the thermodynamic theories of polymer solutions of Flory, Huggins, Gee, and Scott is outlined. The plot of cumulative volume of precipitate against percent nonsolvent has two characteristic features: an inflection point and a maximum. If the original polymer has a weight distribution function of the Schulz type, i.e., MkM × (1 − k)2, where k is related to the number‐average molecular weight, M̄n, through M̄n = M0(1 − k)−1, then it can be shown that the maximum occurs at M̄n while the inflection point occurs at 2.15 M̄n.
Cross‐linking in the polymerization of vinyl benzoate and related compounds
Authors: Ham George E. , Ringwald Eugene L. 
Published: April 2003

AbstractBranching and cross‐linking are noted in emulsion and mass polymerizations involving vinyl benzoate and nuclearly substituted vinyl benzoates. A theory is proposed to account for this phenomenon based on free radical addition to the benzoate nucleus. Six new vinyl esters of substituted benzoic acids are described.
Étude sur les phénomènes de dissolution du chlorure de polyvinyle
Authors: Corbiere Jacques , Terra Pierre , Paris René 
Published: April 2003

AbstractAprès avoir rappelé quelques considérations générales concernant la mise en solution des hauts polymères dans les liquides organiques, les auteurs relatent les principaux résultats de leurs expériences sur la solubilisation des chlorures de polyvinyle industriels dans les liquides binaires. Ils montrent qu'en pastillant par compression le polymère il est possible d'examiner sur ces comprimés l'action de divers liquides et distinguent: (1) les liquides inertes; (2) les liquides désagrégeants; (3) les liquides gélatinisants. Les meilleurs solvants binaires se présentent généralement sous forme de mélange d'un liquide gélatinisant et d'un liquide désagrégeant ce qui revient à combiner l'action d'un liquide polaire et d'un liquide non polaire.Ils montrent ensuite comment on peut apprécier le pouvoir solvant d'un solvant binaire en fonction de sa composition en mesurant la vitesse de pénétration de ce dernier dans une pastille de polymère. Les courbes obtenues ainsi accusent des maxima correspondant sensiblement à des rapports stoechiométriques simples entre les molécules des deux constituants.Ils insistent ensuite sur la nécessité de considérer un phénomène de solvatation comme facteur de gélification et, par suite, comme premier stade de la dissolution. Ceci s'appuie sur leur détermination des degrés de solvatation du chlorure de polyvinyle au moyen de la méthode graphique des restes. Ces solvates font intervenir un seul ou deux des constituants du liquide binaire utilisé comme solvant. Mais dans le cas d'une fixation simultanée des deux constituants du solvant sur le polymère il y a lieu de considérer une action individuelle de ces deux constituants, les propriétés physiques des mélanges étudiés excluant en effet l'hypothèse de complexes d'addition dans le solvant binaire lui‐même.Enfin les auteurs pensent que la solvatation des molécules du polymère persiste dans la solution colloïdale de ce dernier et annoncent qu'ils poursuivent actuellement leurs essais dans le but de mettre cette solvatation en évidence.
Mechanical properties of discrete polymer molecules
Authors: Baker W. O. , Mason W. P. , Heiss J. H. 
Published: April 2003

AbstractA frequency‐dependent stiffness μB was found from the action of high frequency shear waves on dilute solutions of polyisobutylene, polypropylene, polyethylene, polystyrene, hevea rubber, and polybutadiene microgel. A dynamic viscosity associated with streaming of solvent through the molecular coil, ηB, dropped far more rapidly with rising temperature than solvent viscosity, denoting that it, too, reflected configurational changes. (The μB for polyisobutylene in solution declined moderately with rising temperature, corresponding to an exponential coefficient of 2.3 kcal.) This behavior suggested three chief mechanisms for deformation of isolated chains: (1) viscoelastic configuration changes (W. Kuhn's “macroconstellation changes”) with contribution to rigidity per average molecule per cubic centimeter of solution of 〈 μ2 〉 or force constant 〈 f2 〉; (2) temporary entanglements of interpenetrating segments in the chain coil (like the interchain entanglements in concentrated solutions of J. D. Ferry), with contribution to rigidity 〈 μ3 〉; and (3) restrictions to rotational flexibility around chain linkages, with rigidity contribution 〈 μ4 〉. Arrangement of these processes in parallel with solvent viscosity yielded frequency‐independent constants in agreement with the limited data so far obtained in the 103 to 108 cycle range.Such a model gave molecular mechanical constants correlating roughly with chemical structures. For polyisobutylene, force constants per average molecule were 〈 f2 〉 = 17.1 × 10−13 dyne cm., 〈 f3 〉 = 6.3 × 10−12 and 〈 f4 〉 = 1.6 × 10−10. Lower molecular weight (1.2 × 106 vs. 3.9 × 106) gave slightly lower values. 〈 f4 〉 represents restrictions to rotation per isobutylene residue in the chain of 2.3 × 10−15, or about 104 less than valence bond infrared vibrational or twisting force constants for hydrocarbons. The combined average chain rigidities expressed by the force constant 〈 fB 〉, at 20 kc. and 25°C. were, for polyisobutylene of M̄V ∼ 106, 1.8 × 10−12; hevea rubber of M̄V = 2.3 × 105, 1.5 × 10−15; polystyrene of M̄V = 2.3 × 105, 4.5 × 10−16. Hence, single polystyrene chains are quite flexible, but polybutadiene microgel has 〈 fB 〉 = 5.2 × 10−11, for M̄W ∼ 18 × 106, showing effect of internal cross‐linking.“Poor” solvents (“solvent power” μ > 0) caused chain rigidity of polyisobutylene and polystyrene to decrease, compared to good solvents (“solvent power” μ ∼ 0), and viscosity decreased also. Apparent decrease in 〈 fB 〉 apparently means external (solvent) “compression” of chain, and agrees with technological efficiency of poorly compatible plasticizers.Complete theory of effects has been outlined by Kirkwood, for a rod model. Great range of rigidities shown even by hydrocarbon chains (intrinsic rigidity of polyethylene soln., [μ] = 906 dynes/cm.2, of polypropylene soln., [μ] = 92 dynes/cm.2) has not yet been treated, however.
Absolute propagation rates in emulsion polymerization. II. Butadiene in hydroperoxide‐polyamine systems
Authors: Morton Maurice , Salatiello P. P. , Landfield H. 
Published: April 2003

AbstractA study has been carried out on the emulsion polymerization of butadiene, using the “peroxamine” recipe at low temperatures in an attempt to evaluate the absolute propagation rate, according to the theory of Smith and Ewart, from a determination of the rate of polymerization per particle of latex. Unlike the persulfate‐mercaptan system previously reported, the hydroperoxide‐polyamine systems show a polymerization rate per particle which is independent of all variables other than temperature. Hence this system behaves according to case 2 of the Smith‐Ewart treatment, where the number of free radicals per particle is approximately 1/2. On this basis it is possible to calculate a value for the absolute propagation rate constant for butadiene, as follows: kp = 1.2 × 108 e−9300/RT l./mole/sec. This value in turn leads to an evaluation of the absolute rates of some other reactions involving the butadiene radical, such as cross‐linking, chain transfer, and copolymerization. It agrees with the current data on absolute rates for other monomers and with present‐day theories concerning the effect of conjugation on radical‐monomer interaction.
Relation of composition of polyvinyl acetals to their physical properties. I. Acetals of saturated aliphatic aldehydes
Authors: Fitzhugh Andrew F. , Crozier Robert N. 
Published: April 2003

AbstractPolyvinyl alcohol was condensed with straight and branched chain aldehydes (CnH2nO, n = 2 to 8) to varying degrees of completion. Measurements on resins and plasticized compositions included apparent modulus of elasticity at various temperatures, brittle temperature, tensile strength and elongation, and solubility. From these measurements it is concluded that: (1) Increasing degree of acetalization results in lowered transition temperature, lower stiffness at transition, narrower transition range, higher brittle temperature, decreased tensile strength, and shift in solubility toward solvents of lower dielectric constant. (2) Acetals of higher normal aldehydes have lower transition and brittle temperatures, lower tensile strength, and more limited solubility. (3) Branched chain aldehydes have higher transition and brittle temperatures than their normal isomers.
Absolute propagation rates in emulsion polymerization. III. Styrene and isoprene
Authors: Morton Maurice , Salatiello P. P. , Landfield H. 
Published: April 2003

AbstractThe study of the rate of polymerization per particle in emulsion systems has been extended to include the following monomers and initiator systems:

Monomer
Initiator System

Styrene
Persulfate

Styrene
CHP‐TETA

Isoprene
DIBHP‐TEPA

In all cases, linear rates of polymerization were obtained in the region where the number of particles can be considered as remaining constant (30–60% conversion). Furthermore, the addition of catalyst in this region did not affect the rate of polymerization, so that a rate per particle could be calculated. From the rates per particle, the following absolute propagation rates were calculated for styrene and isoprene, and are compared with values obtained for styrene from photoinitiation studies:

Monomer
Catalyst system
Eact.
A
kp at 60°C.

Styrene
Persulfate
7.4
4.1 × 107
277

Styrene
CHP‐TETA
8.4
3.3 × 107
221

Styrene
Photoinitiation
7.8
2.2 × 107
176

Isoprene
DIBHP‐TEPA
9.8
1.2 × 108
50
Nouvelle chambre de diffraction de rayons X pour les fibres
Authors: Legrand C. 
Published: April 2003

AbstractUne chambre de diffraction de rayons X spécialement adaptée à l'étude des fibres et des hauts polymères a été construite. Conçue de façon à utiliser un rayonnement strictement monochromatique obtenu par réflexion sur un cristal de quartz courbé (méthode Guinier), elle permet deplacer l'échantillon dans une atmosphère contrôlée et à une température déterminée. Le film est isolé de “l'espace laboratoire” et est maintenu dans le vide. La qualité des diagrammes a été considérablement améliorée par cette technique.
The number‐average molecular weight of polythene
Authors: Harris Ivan 
Published: April 2003

AbstractDirect determinations of the number average molecular weights of a variety of British and American polythenes have been made making use of two experimental techniques: (1) ebulliometry and (2) high temperature osmometry. An intrinsic viscosity‐molecular weight relation has also been obtained which covers the range 1.3 × 103 to 76 × 103 and includes representative samples of Alkathene. The Huggins constants k' and μ have been evaluated from viscosity and osmotic pressure data and their bearing on polythene structure discussed.
Réactions de condensation de formaldéhyde et d'urée
Authors: Smets G. , Borzee A. 
Published: April 2003

AbstractThe condensation reaction of urea and formaldehyde was studied in a molar ratio 1:1 and 1:2 of both components; the reaction always proceeds by a second‐order mechanism. These reactions were compared and found analogous to the condensations of pure mono‐ and dimethylolurea. In neutral medium, by measuring at 65, 75, and 85° the value obtained for the energy of activation was 21 kcal./mole for both reactions; the 1:2 ratio‐condensation reaction is nevertheless three times slower than the 1:1 condensation. In acidic medium, a pure acid catalytic effect was found to be true, and the rates of the reaction between pH 3 and pH 5 were proportional to the hydrogen‐ion concentration; the activation energy was evaluated at about 8–10 kcal. for the acidic condensation reaction. At higher pH values, both reactions, thermal and acid‐catalytic, occur together, and the exponent to the hydrogen‐ion concentration in the expression of the rate of condensation appears to be smaller than unity. Analytical determinations of the condensation products are given and a likely kinetic scheme for the reaction is indicated.
Solubility and fractionation of polyvinylpyrrolidone
Authors: Jirgensons B. 
Published: April 2003

AbstractPolyvinylpyrrolidone (PVP) can be conveniently fractionated from water by successive precipitation with acetone, from chloroform with ether, or from ethanol with benzene. The major part (60–70%) of the common PVP has the intrinsic viscosity of 0.12–0.30. The fractions can be liberated from the low molecular components by extraction of the solid polymer with acetone. Precipitability with ammonium sulfate is a very convenient means of characterizing the fractions. The amount of ammonium sulfate needed to produce turbidity decreases with increasing mean molecular weight of the fractions, with the increasing concentration of the polymer, and with increasing temperature. The molar concentration of ammonium sulfate that produces turbidity is a linear function of the logarithm of the mean molecular weight of the fractions. The amount of ammonium sulfate which produces turbidity decreases linearly with increasing temperature.
Elastoviscous properties of polyisobutylene. V. The transition region
Authors: Tobolsky A. V. , McLoughlin J. R. 
Published: April 2003

AbstractA discussion of the principles for the extension of the time scale for elastoviscous data by use of experimental information obtained at various temperatures is presented. A quantity k is defined such that stress relaxation curves at all temperatures are identical if plotted versus time divided by k(T). This function k(T) is compared with the function a(T) used by Ferry and by Fox and Flory for other viscoelastic data. In particular, k(T) for polyisobutylene is found to be identical (within experimental error) with a(T) obtained by Fox and Flory from viscosity measurements.The complete composite relaxation curve Er,T(t) for polyisobutylene is constructed from data of Brown and Tobolsky and Andrews and Tobolsky. Er,T(t) is shown to have three regions: a “rubbery region,” and a “glassy region.” This conclusion is reinforced by comparison with data on polymethylmethacrylate. The “rubbery region” is molecular weight dependent, whereas the “transition region” is molecular weight independent and independent of the presence of a small concentration of cross links.Simple empirical functions are given for Er,T(t) and the corresponding distributions of relaxation times are also presented.
Study of degradation of polystyrene by means of mass spectrometry
Authors: Achhammer B. G. , Reiney M. J. , Wall L. A. , Reinhart F. W. 
Published: April 2003

AbstractThe degradation of polystyrene by heat and ultraviolet radiant energy was followed by mass spectrometric analysis of the gaseous products evolved. Oxygen content, discoloration, and insolubility of the treated polymer were also investigated. The degradation of polystyrene involves two different processes: (1) the breakdown of thermolabile groups formed in the polymer prior to degradative treatment; this breakdown is caused by exposure to heat at 120°C. in vacuo and 115°C. in oxygen and to ultraviolet radiant energy at 120°C. in vacuo and 118°C. in oxygen; it is accompanied by the removal of residual materials such as solvent; and (2) the oxidation of the polymer caused by exposure to ultraviolet radiant energy in the presence of oxygen. The evolution of benzene, methyl ethyl ketone, dimethylbenzenes, and alcohols is associated with the first stage involving the breakdown of thermolabile groups and the removal of residual materials. Compounds such as formaldehyde, formic acid, and acetic acid are produced as a result of oxidation of the polymer. The oxygen content of the polymer was decreased from 0.33 to approximately 0.1 percent by heating at 120°C. in vacuo and at 115°C. in oxygen, and by exposure to ultraviolet radiant energy at 120°C. in vacuo. Ultraviolet treatment at 118°C. in oxygen for 250 hours quadrupled the original oxygen concentration. Discoloration of the polystyrene was definitely noted only on exposure to ultraviolet radiant energy in oxygen and is associated with oxidation of the polymer. The material became insoluble as a result of all heat and ultraviolet treatments. The amount of insoluble material increased with severity of exposure conditions.
Effect of the velocity gradient on intrinsic viscosity of polymers in solution
Authors: Peterlin A. 
Published: April 2003

AbstractFor a soft free‐draining coil that changes its shape quite easily in flow, intrinsic viscosity does not depend on velocity gradient. The deformation and extension of the coil in flow, which increases the contribution of the single molecule, is just compensated for by the decrease in number of molecules crossing the flow plane and thus actually contributing to the additional shear stress. The finite valence angle and the restricted rotation around the valence bond, however, not only extend but also stiffen the molecule. The completely stiff coils—an idealization that never occurs but is very suitable for computing purposes—are oriented in the flow without any alteration of their shapes and shape distribution. The intrinsic viscosity thereby decreases with increasing orientation. The effect is the more accessible the longer the molecule, the deviations from the initial viscosity at rest being proportional to the square of the gradient and the fourth power of the degree of polymerization. The real molecules are neither quite stiff nor completely soft. Thus their intrinsic viscosity ought to lie between the two limiting cases, the decrease with the gradient being smaller than for the stiff coils. Taking into account the hydrodynamic interaction of the chain elements, the gradient dependence cannot be computed precisely. Qualitative considerations yield an increased viscosity contribution with the stretching of the coils, since they become more permeable the more they are extended. Thus the intrinsic viscosity of quite soft molecules should increase with the gradient. In completely stiff coils, however, the partial solvent immobilization does not change the gradient dependence, on the whole, since the shapes and the shape distribution are unaltered by the flow, although the appearing of the effect is displaced to higher gradients, and the absolute value of the initial intrinsic viscosity is very markedly reduced. Experiments are too rare and not sufficiently precise to allow any reliable test of the theory. In most cases, the concentrations and the gradients are too high for an unambiguous extrapolation to infinite dilution and zero gradient viscosity. But they nevertheless seem to exclude the case of quite soft molecules and are not in contradiction with the general features of the theory.