bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyelectrolytes. XII. Conductance of partially quaternized poly‐4‐vinylpyridine in methanol‐butan‐2‐one mixtures
Authors: MacFarlane Robert , Fuoss Raymond M.
Published: April 2003

By partially quaternizing polyvinylpyridine with n‐butyl bromide, a series of polyelectrolytes were obtained in which from Q = 3 to Q = 20% of the pyridine nitrogens were converted to butylpyridinium ions. These products thus are copolymers of ionic and nonionic units. Their conductance was measured over the concentration range 10−4 ≤ c ≤ 3 × 10−3 equivalent of bromide ion per liter in mixtures of methanol and butan‐2‐one (MEK) ranging from pure methanol to a 20:80 MeOH–MEK mixture. The viscosity of the solvent was thereby varied from 0.00546 to 0.00400 poise and the dielectric constant from 32.6 to 21.6. The phoreograms (Λ−c1/2 curves) are all sharply concave‐up, indicating a high degree of association of counterions with the polymeric ions in this range of concentration. The product of equivalent conductance and solvent viscosity gives a dependent variable which accounts for the primary hydrodynamic effect of changing solvent, showing that the ionic mobilities are determined by local viscosity rather than by macroscopic solution viscosity. Plots of log Λη are linear in reciprocal dielectric constant, and therefore ionic association for a given salt is controlled by electrostatic forces. As degree of quaternization decreases, the equivalent conductance increases (other variables remaining constant); this change corresponds primarily to decrease in association of counterions as the charge density of the polycation is decreased. The fact that observed conductances extrapolate to values greater than the single bromide ion conductance in the limits c = 0, Q = 0 shows that cationic sites in the chains are capable of contributing to conductance in alternating fields. Therefore a rigid model represents an oversimplification for the a.c. conductance of polyelectrolytes, although it probably will serve well for d.c. conductance.
Phase separation of polyelectrolyte solutions
Authors: Michaeli I. , Overbeek J. Th. G. , Voorn M. J.
Published: April 2003

It is shown theoretically that phase separation may arise in solutions of polyelectrolytes due to electrostatic interactions alone. Two models are considered thermodynamically. In both models the free energy is represented as the sum of an entropy of mixing term and an electrostatic free energy term, while the van der Waals attractions are neglected. In the one model, electrically charged rigid cylindrical rods are in solution with an equivalent amount of counterions but without additional electrolyte. The free electrical energy, in this case, is given by the expression of Lifson and Katchalsky. In the other model the solution contains two types of macroions of opposite charge. The macroions are flexible coils carrying a number of univalent charges, the charge density being sufficiently low. The electrical free energy in this case may be approximated by the Debye‐Hückel expression. For both models, it is shown that the decrease in the electrical free energy in a phase separation can, at given temperature and pressure, more than compensate for the increase in the entropy of mixing term. The effects of polymer concentration, dielectric constant, charge density, and salt content follow directly from the thermodynamic treatment of the models.
Sur l'activité des ions dans les solutions colloidales. III. Variation du coefficient d'activité des ions compensateurs en fonction de la concentration
Authors: Bourdais J. , Dobry‐Duclaux A.
Published: April 2003

L'activité des counter‐ions a été déterminée électrométriquement, en solution aqueuse, pour deux séries de polyélectrolytes anioniques: (I): sels d'argent d'acide polyacrylique et des copolymères d'acide acrylique et d'acrylamide–(II): sels d'argent des copolymères d'acide maléique et d'acrylamide. II résulte: (I) que le coefficient d'activité f(a) des counter‐ions est lié à leur concentration c par l'expression:

valable pour tous les polyélectrolytes étudiés. (2) Que f(a) dépend essentiellement, par l'intermédiaire du paramètre K de la relation (1), de la densité ρ groupes ionisables du polyélectrolyte; le paramètre K, identique à une constante moyenne d'association, croǐt rapidement avec ρ, mais selon des lois différentes pour les deux séries de polyélectrolytes: en particulier, dans les polyélectrolytes du type (II), le voisinage des deux groupes carboxyle entraine un renforcement de l'association des counter‐ions, indépendamment de l'effet de densité globale des groupes ionisables. On déduit, de ces résultats, que la sélectivité d'une résine échangeuse d'ions sera d'autant plus grande, tout au moins, vis à vis d'ions s'associant fortement, comme l'ion argent, à ses sites d'échange, que la densité de ces sites sera plus élevée.
Viscosity behavior of polyelectrolyte solutions at low and medium rates of shear
Authors: Eisenberg H.
Published: April 2003

The viscosity of dilute aqueous solutions of polyelectrolytes has been reinvestigated with the help of an improved model of a rotation viscometer with electrostatic restoring torque recently described. The experimental variables included rate of shear, composition of the medium, concentration, and degree of polymerization of the solutes. The limiting slopes of the viscosity numbers of polymethacrylic acid as a function of the rate of shear have been found to be horizontal, in accord with hydrodynamic theory. The limiting viscosity numbers of fractions of polymethacrylic acid, poly vinylpyridiniumbutyl bromide and sodiumcarboxy methylcellulose are analyzed. A discussion of experimental methods used for the study of rate of shear dependence of the viscosity of polyelectrolytes is given.
Etude expérimentale de l'effet électrovisqueux présenté par un polyélectrolyte rigide
Authors: Donnet J. B. , Marguier P.
Published: April 2003

Nous avons utilisé dans notre étude de l'effet électrovisqueux des suspensions aqueuses de noir de carbone, très stables, obtenues après traitement chimique. Ces suspensions contiennent des particules de noir de carbone de forme approximativement sphérique, parafaitement rigides et qui portent en surface des groupements chimiques qui leur confèrent le caractère de polyélectrolyte. Nous avons étudié la viscosité de la solution lorsque l'on fait varier la constante diélectrique ε du milieu dispersant soit par addition à l'eau d'un solvant miscible de basse constante‐diélectrique tel que l'alcool éthylique, soit par variation de la température. Nous avons également étudié l'influence sur la viscosité de l'addition au milieu de dispersion de sel neutre (KCl) d'acide fort (HCl) et de base forte (KOH). En dehors des observations viscosimetriques on a noté qu'il y a floculation reversible du sol lorsque l'on diminue suffisement ε, tandis que le sol ne flocule pas en milieu KOH, quelle que soit la concentration en KOH. Ces deux observations ne semblent pas avoir de précédent. Le comportement du sol en milieu KCl est classique, c'est‐a‐dire qu'il y a floculation pour des concentration suffisantes en sel. La floculation apparait plus vite par addition d'HCl que de KCl. On peut tirer de l'étude les conclusions suivantes: (1) Les résultats expérimentaux mettent en évidence un accroissement de viscosité provoqué par l'apparition de ce que l'on a dénommé la “floculation limitée” phénomène qui ne se manifeste pas sur l'état apparent du sol et que décèle seulement l'augmentation de K. Ce phénomène sera suivi de la floculation proprement dite si l'on continue à abaisser ε ou à augmenter la concentration ionique. On propose une explication simple de la floculation limitée et de l'accroissement de viscosité qui l'accompagne. (2) Dans le domaine où les sol est soumis au seul effet électrovisqueux la théorie de Booth permet une interpretation satisfaisante des résultats viscosimetriques. (3) Les résultats obtenus montrent que la stabilité du sol étudié dépend nettement de la grandeur de la charge portée par les particules et de l'épaisseur de la double couche approximée par le paramètre x−1 selon Debye.
Etude de la morphologie de macromolécules par mesures de pressions superficielles
Authors: Jaffe J. , De Coene R.
Published: April 2003

Il est bien connu que l'on peut obtenir au départ de mesures de la pression superficielle les poids moléculaires et les cosurfaces des molécules étalées sous forme d'un film mono‐moléculaire. Nous avons essayé d'établir une rélation étroite entre les cosurfaces spécifiques et les dimensions linéaires des molécules. On montre ainsi que dans le cas de deux protéines à dissymétrie élevée, la gliadine et la zéine, il existe une relation linéaire entre les cosurfaces spécifiques et le poids moléculaire. En combinant les résultats de la pression superficielle à ceux de la densité moléculaire il est possible de calculer le rapport des axes. Les résultats sont en bon accord avec ceux indiqués par d'autres méthodes.
Impregnated membranes with specific permeabilities for different ions
Authors: Hirsch‐Ayalon P.
Published: April 2003

The properties of a new type of impregnated membrane are described, a BaSO4 cellophane membrane being taken as an example. Unusually high membrane potentials are observed. The membranes can generate galvanic electricity and show selective semipermeability.
Solubilité et dissociation d'une désoxyribonucléoprotéine
Authors: Oth A. , Desreux V.
Published: April 2003

La solubilité du DNP a été étudiée à force ionique constante et différents pH ou à pH constant et à différentes concentrations salines. Sur la base des résultats obtenus, les auteurs proposent une méthode de préparation d'histone et de DNA.
Application of the titration method to studies on the denaturation of sodium deoxyribonucleate
Authors: Cox R. A. , Peacocke A. R.
Published: April 2003

A method is described whereby the difference between the irreversible forward titration curve from neutrality to pH 2.5 and the reversible back titration curve from pH 2.5 can be used to determine the extent and character of denaturation (i.e., rupture of hydrogen bonds) in various treatments of sodium deoxyribonucleate (DNA) prior to titration. On this basis, the effects of heat, ultrasonic waves, and γ‐rays are examined. Denaturation by ionization of the hydrogen‐bonded amino groups has been studied as a function of temperature and of pH. Some of the kinetic and statistical consequences of the observations are discussed in terms of a model requiring the rupture of a minimum sequence of hydrogen bonds for denaturation to occur.
An estimate of the molecular weights of polythene
Authors: Mussa Carlo
Published: April 2003

The MW determinations of polythene made by Harris are matched by calculation together with the results of our fractionations carried by a method suggested by Nicolas. An evaluation of the MW and of their distribution in a set of polythene samples is obtained which is in agreement with the long branching hypothesis. The calculation of Beasley can be satisfactorily applied and values of the long branching parameters have been calculated for the examined samples.
Polymerization and polymers of N‐vinylpyrrolidone
Authors: Breitenbach J. W.
Published: April 2003

Experiments are reported on the rate of polymerization of N‐vinylpyrrolidone in the presence and in the absence of azobisisobutyronitrile as initiator. The reactions of N‐vinylpyrrolidone in aqueous acid solution are mentioned. The limited degree of swelling of crosslinked polyvinylpyrrolidone is discussed. Degree of swelling is influenced by choice of solvent, by temperature and, in aqueous systems, by ions which are present on the network of the gel. These ionized groups can be introduced by copolymerization with unsaturated acids or by adsorption of ions from solution. Certain dyes are especially suitable for the formation, in this way, of polyelectrolyte gels having a low charge density.
Some aspects of the crystallization of nylon 66 (polyhexamethylene adipamide)
Authors: Boasson E. H. , Woestenenk J. M.
Published: April 2003

A study has been made of crystallization phenomena in nylon 66 occurring after fusion at temperatures just above the melting point. It appeared to be possible to obtain optically negative spherulites in nylon 66 by crystallizing at temperatures between 250 and 258°C., after fusion at temperatures above 258 but below 265°C. The radial growth rate of the negative spherulites has been determined and has been found to depend on the crystallization temperature. The optically negative spherulites have a higher optical melting point than the optically positive spherulites hitherto observed in nylon 66. Another type of spherulitic structure with spherulites of a fibrous appearance, of which the optical sign cannot be determined, is reported. An attempt is made to explain the data obtained on the basis of the generally accepted crystallization mechanism, valid for linear high polymers.
Measure of permeability of plastic material, leather, and similar substances against moistness and water by the hygrophotographic method
Authors: Sivadjian J.
Published: April 2003

The hygrophotographic method which the author has elucidated with the help of special hygrosensitive plates and films described by him, permits a study of the permeability of different kinds of plastic materials, leather, and other analogous substances in water as well as in vapor. With this aim in view, it gives the time necessary to produce the decoloration of the hygrosensitive layer of the hygrophotographic plates kept in contact with these products, by the action of vapor diffused through the products examined. The different phases of the decoloration are fixed afterwards by direct photography.
Mechanism of retardation in emulsion polymerization of styrene
Authors: Meehan E. J. , Kolthoff I. M. , Tamberg Nora , Segal C. L.
Published: April 2003

Emulsion polymerizations of styrene have been carried out with potassium persulfate as initiator and fatty acid soap as emulsifier in the presence of varying amounts of N,N‐dimethyl‐2,4‐dinitroaniline (DMDNA) and 1‐bromo‐2,4‐dinitrobenzene (BrDNB). The latter two substances are retarders. Rates of polymerization, rates of disappearance of retarder, and polymer molecular weight were determined. The ultraviolet spectrum of the retarded polymer showed conclusively the presence of bound DMDNA while the amount of bound DMDNA was determined by a spectrophotometric acid‐base titration with perchloric acid of the polymer dissolved in benzene. BrDNB was prepared using Br82 and the amount of retarder fragments in the polymer determined by radioactive measurement. The quantities of persulfate remaining and of sulfate formed were determined during polymerization strongly retarded by DMDNA. All the results are in quantitative agreement with the following mechanism. The rate‐determining step in initiation is the rate of thermal decomposition of persulfate in water into sulfate free radicals. The sulfate radical reacts with monomer to initiate polymerization. In the absence of retarder, growth is terminated either by chain transfer with monomer or by combination with a second sulfate radical. In the presence of retarder the growing radical may combine with retarder, forming a sluggish free radical to which monomer does not add, and which is terminated by reaction with a second sulfate radical. In this reaction a hydrogen atom is transferred yielding a polymer molecule and a bisulfate ion.
Molecular weight‐intrinsic viscosity relationship and molecular weight distribution of low pressure polyethylenes
Authors: Tung L. H.
Published: April 2003

Molecular weights of low pressure polyethylene fractions were measured by an ebulliometric method and an osmotic pressure method. The results can be correlated by an equation, [η] = 5.10 × 10−4 M0.725, with the intrinsic viscosity measured at 130°C. in Tetralin, for a molecular weight greater than 3750. All three types of polymer fractions, Ziegler‐type low pressure polyethylene, Phillips low pressure polyethylene, and polymethylene from the decomposition of diazomethane, conform to the above correlation. The molecular weight distributions of two samples of Ziegler type polyethylene and one sample of Phillips' Marlex 50 were determined. All three distributions were found to be very broad and contained large amounts of low molecular weight materials.
Measurement of birefringence of biaxially oriented films
Authors: Stein Richard S.
Published: April 2003

A technique for characterizing the optical properties of biaxially oriented films is described. This involves measuring the optical retardation as a function of the tilt angle of the film. The method is illustrated for a film of biaxially oriented polystyrene.
Scattering of light by thin polymer films. An apparatus for measurement of scattering at very low angles
Authors: Plaza Alphonse , Norris Forrest H. , Stein Richard S.
Published: April 2003

An apparatus is described for studying the scattering from polymer films at angles to within 0.1° from the incident beam. A temperature‐controlled chamber for carrying out these measurements at elevated temperatures is also described. The performance of the apparatus in measuring the scattering from a polyethylene film is illustrated.
Wettability and friction of polytetrafluoroethylene film: effect of prebonding treatments
Authors: Allan A. J. G.
Published: April 2003

The wettability of polytetrafluoroethylene film surfaces has been studied by observing the equilibrium advancing contact angle formed by a drop of liquid on the surface. The surface treatment required to give good adhesion to various substrates produces a marked increase in the polarity of the surface as measured by the contact angles with a series of solutions of ethyl alcohol in water. Measurement of the coefficient of kinetic friction shows that the untreated side of treated material has the same coefficient as completely untreated film, but the treated side has a considerably higher friction. This higher friction of the treated surfaces is ascribed to the shearing of junctions in the bulk rather than shearing at the interface.
Dielectric studies of the methacrylate series. II. Poly‐n‐butyl methacrylate
Authors: Strella Stephen , Zand Robert
Published: April 2003

The complex dielectric constant of a pure molecular weight fraction of poly‐n‐butyl methacrylate was determined over a frequency range of 30 to 3 × 105 cps. and a temperature range of −74 to 114°C. The d.c. volume resistivity–temperature behavior was also determined. The data indicate the presence of two transition regions. Comparison of these data with those on polyethyl methacrylate shows that the transitions in the butyl polymer are further apart in temperature than in the ethyl polymer. Further, the data show that the ethyl chain is stiffer than the butyl chain. An attempt at superposition of the normalized complex dielectric constant was unsuccessful. Calculation of the distribution function of relaxation times for several temperatures shows a marked temperature dependence of this function.
Crosslinking of oriented rubber
Authors: Charlesby A. , von Arnim E.
Published: April 2003

Smoked sheet rubber, previously oriented in the calendering process, was crosslinked by exposure to 2 M.e.v. high energy electrons in the absence of vulcanizing agents. Even after annealing the resultant rubber showed anisotropic elastic properties, having a high elastic modulus and a low elongation at break in the direction of orientation. It is suggested that radiation in addition to crosslinking causes main chain fracture and stress relaxation in stressed molecular chains. The G value for crosslinking (1.05) by electron irradiation agrees well with that (1.1) previously found by elastic measurements of pile irradiated rubber.
Ultrasonic degradation of cellulose nitrate. II. Effects of temperature, solvent, and other process variables
Authors: Thomas Berwyn B. , Alexander W. J.
Published: April 2003

Cellulose nitrate was degraded ultrasonically at 0 to 85°C. in the alkyl acetates from methyl to heptyl. In each solvent there is a high and low limit temperature where cavitation and degradation both cease. The upper limits are at the temperatures where vapor pressure of the solvent is about one‐half atmosphere, and cavitation evidently ceases because the solvent vapor pressure becomes too great for rapid bubble collapse. The lower limits of pressure and temperature vary in a linear manner, but have not been explained. The results confirm the need for cavitation as an initiator of the degradation mechanism, and explain some effects previously ascribed to solvent viscosity and temperature. When radio frequency power was varied, the rate of degradation was found to be independent of power so long as cavitation was present. In other experiments, degradation was found to be approximately constant to concentrations much lower than previously tested, whereas some proposed mechanisms would require that it should be reduced by dilution. Addition of a nonsolvent reduced the intrinsic viscosity of the polymer solution but did not reduce the extent of degradation; thus degradation is a function of the chain's length but not of its solvation. Finally, comparison of a series of celluloses from diverse sources showed that all gave about the same minimum degradable chain length, of 800–1000 DP. It was concluded that there was no evidence for the existence of weak links in the celluloses at shorter intervals.
Surface and interfacial monolayers of high polymers
Authors: Schick Martin J.
Published: April 2003

The monomer structure of several linear high polymers in monolayers has been studied with an automatic recording film balance and surface potentiometer of very high precision. The method is based on the resolution of the monomer structure from estimation of the limiting areas of the force—area and surface—potential area curves. The structures of poly(vinyl acetate), poly(vinyl alcohol), poly(methyl methacrylate), poly‐(methacrylonitrile), and ethoxylin polymer have been determined. In addition the secondary cohesion, which corresponds to its three‐dimensional equivalent, was related to the stability of the polymer film. It was found in the vinyl polymer series that secondary cohesion decreased in the order poly(vinyl alcohol), poly(methacrylonitrile), poly(methyl methacrylate), poly(methyl acrylate) to poly(vinyl acetate). Alternatively a comparison of specific areas at A/W and O/W interfaces renders conclusion on the rigidity of a polymer. Whereas poly(vinyl acetate) showed identical areas at both interfaces, poly(methyl methacrylate) spread to larger areas at the O/W interface. From this it is evident that the α‐methyl group in the vinyl chain exerted strong cohesive forces. This effect was even more pronounced with the ethoxylin resin with two benzene rings in the monomer unit. Application of a statistical mechanical equation for the two‐dimensional behavior of linear polymer indicated also that whereas poly‐(vinyl acetate) is a flexible chain, ethoxylin polymer is a rigid chain.
Intrinsic viscosity–molecular weight relationship for polychlorotrifluoroethylene
Authors: Walsh Eugene K. , Kaufman Herman S.
Published: April 2003

A high temperature osmotic pressure technique has been used to obtain molecular weight data on fractions of polychlorotrifluoroethylene. Samples representing a range of molecular weight of 74,000 to 510,000 were studied. Intrinsic viscosity data were obtained on the samples at 130°C. using a dilution viscometer. The principal solvent used in these studies was 2,5‐dichlorobenzotrifluoride. The plot of π/C vs. C yields satisfactory linear relationships with a slope closely equal to zero. The log log plot of molecular weight and intrinsic viscosity gives the following relationship:

The value of the exponent 0.74 suggests a relatively rigid molecule. This is consistent with the results of x‐ray studies.
Polyalkylene sulfides. XIII. Polymers from 4‐vinyl‐1‐cyclohexene and d‐limonene
Authors: Marvel C. S. , Olson L. Elmer
Published: April 2003

4‐Vinyl‐1‐cyclohexene and d‐limonene have been converted to dimercaptans by the addition of thiolacetic acid and subsequent hydrolysis. These dimercaptans have been added to the original nonconjugated diolefins to give low melting highly viscous polymers. In the case of 4‐vinyl‐1‐cyclohexene two monoaddition products of thiolacetic acid have been isolated and characterized. The ratio of the two products indicates two parts of adduct to the cyclohexene double bond to three parts of adduct to the vinyl group double bond are produced in the addition reaction.
Fibrous and globular aggregations of charged macromolecules
Authors: Oosawa Fumio
Published: April 2003

The dispersion‐aggregation equilibrium of charged macromolecules in solution is discussed. The aggregates of charged macromolecules formed by the short‐range attraction between molecules are, under suitable conditions, made fibrous owing to the longrange repulsion between them. As a result of calculations, a phase diagram is obtained and the size and shape of aggregates are determined by the values of the two dimensionless quantities defined by use of the following quantities: chemical potential difference between macromolecules in the macroscopic phase of aggregation and in the dispersed phase; surface free energy per macromolecule on the surface of macroscopic aggregates; magnitude of the long‐range repulsive potential between macromolecules, and the range of this potential. The states of aggregation are classified into five groups: (1) macroscopic globular aggregation; (2) macroscopic fibrous aggregation; (3) globular aggregation of finite size; (4) fibrous aggregation of finite size; and (5) no aggregation. Discontinuous transitions take place between these states and the critical points are given quantitatively. The change of state of aggregation under various conditions is described. The results of the present theory are proved to be useful in analyzing experimental data on aggregation phenomena in solutions of macromolecules and other colloidal particles.
A suggested method of plotting the data of fractionation and viscometry
Authors: Mussa C. , I. V.
Published: April 2003

When for a given polymer a weight distribution formula is known or may be supposed, the experimental data obtained from its fractionation and from the viscometry of its fractions can be plotted, with a convenient choice of the coordinate system, in diagrams constituted by straight lines (or by lines tending toward linearity) as long as the relationship between the log of the intrinsic viscosities and the log of the degrees of polymerization of homogeneous fractions of the same polymer is also linear (or tending toward linearity). The straight‐line diagrams found by Wesslau in the case of low pressure polyethylene are a particular case of this kind of plot. The Wesslau, the exponential, and the Beasley distribution formulas have been considered, and curves and tabulated values are given to be used when the fractionation and viscometry data of polymers having these distributions are to be expressed in those coordinate systems in which they are represented by straight lines (or by lines tending toward linearity). Certin analytical features of the Wesslau distribution, compared with the other distributions, may suggest some considerations about the mechanism of synthesis of polymers similar, from this point of view, to low pressure polyethylene.
Polymerization of some fluorine‐containing olefin oxides
Authors: Jones F. B. , Stickney P. B. , Coleman L. E. , Rausch D. A. , Lovelace A. M.
Published: April 2003

The polymerization characteristics of six different fluorinated olefin oxides have been studied. The initial effort in this work was on the homopolymerization of 1,1,1‐trifluoro‐2,3‐butylene oxide. Attempts to polymerize this material have been made by mass polymerization over a broad temperature range using a number of different compounds as potential polymerization catalysts. Among these compounds were FeCl3, FeCl3 · 6H2O, AlCl3, a BF3‐etherate complex, KOH, gamma radiation from a cobalt‐60 source, a heterogeneous catalyst formed from aluminum triethyl and TiCl4, and a FeCl3‐propylene oxide complex. All of the polymeric products obtained from these experiments were liquids of a relatively low molecular weight. The highest molecular weight polymers were obtained using FeCl3, AlCl3, and BF3. An attempt was subsequently made to determine the relative polymerizability of other, more highly substituted, fluorinated olefin oxides. These were 1,1,1‐trifluoro‐2,3‐pentylene oxide, 1,1,1‐trifluoro‐2,3‐isopentylene oxide, 1,1,1,2,2,3,3‐heptafluoro‐4,5‐hexylene oxide, 1,1,1,‐2,2,3,3‐heptafluoro‐4,5‐heptylene oxide, and 1,1,1,2,2,3,3‐heptafluoro‐4,5‐isoheptylene oxide. FeCl3 and AlCl3 were found to be effective catalysts for the mass polymerization of these materials to form liquid polymers. It was observed that the tendency to polymerize decreases in this group of compounds as the amount and complexity of substitution on the ethylene oxide nuclcus increases. All of these monomers are less reactive toward polymerization than is trifluorobutylene oxide; as a result, lower molecular weight products were formed in lower yields.
Effect of diluents on fusion temperature of the crystalline regions in plain and tanned cowhide
Authors: Witnauer Lee P. , Fee Jeanne G.
Published: April 2003

Melting (shrinkage) phenomena in plain cowhide were investigated by measuring the temperature at which contraction first occurred in specimens containing varying amounts of ethylene glycol, formamide, phenol, and water as diluents. Similar measurements were made on cowhide specimens which had been tanned with formaldehyde and with a vegetable tannin and contained water as the diluent. In all cases the temperature at which contraction first occurred was found to increase as the diluent concentration was decreased in general accord with the theory of melting‐point depression. The melting temperature of the crystallites in undiluted cowhide was found, by extrapolation of the data of each system to zero diluent content to be about 145°C. The melting temperatures of undiluted tanned cowhide, however, depended on the tanning agent employed. A value of 120°C. was obtained for the vegetable‐tanned cowhide, and 151° for formaldehyde‐tanned cowhide. The former value was verified experimentally by direct measurement. This evidence for a decrease in crystallite stability indicates that vegetable tannin acts as a diluent. The observations indicates that tanning reduces the availability of the amorphous regions to diluents either through a type of crosslinking and/or a reduction in the number of active sites. This accounts for the observed elevation of the commonly measured shrinkage temperature of hide specimens after tanning. In addition, the tanning agents can markedly modify the mechanical properties of the amorphous regions by acting as a plasticizer or stiffening agent. The heats of fusion, ΔHu, for cowhide diluted with glycol, formamide, and phenol were 2200, 1600, and 1800 cal./mole, respectively. However, with water as diluent for plain hide, ΔHu was 7200 cal./mole. Similar values were obtained with the tanned hide. Entropies of fusion, ΔSu, for cowhide diluted with glycol, formamide, and phenol (assuming two bonds per residue freed on melting) were 2.6, 1.9, and 2.2 cal./deg./bond, respectively, while for plain hide, vegetable‐tanned hide, and formaldehyde‐tanned hide diluted with water, the values were 8.5, 9.2, and 9.5 cal./deg./bond. In order to bring the entropy values for the water systems into agreement with the other diluent systems it is necessary to assume that eight bonds per residue are freed on melting.
The molecular and crystal structure of cellulose triacetate
Authors: Dulmage W. J.
Published: April 2003

An x‐ray diffraction study has been made of cellulose triacetate II. Small films of highly crystalline triacetate with good fibrous orientation and a fair degree of biaxial orientation have been prepared by repeated rolling at successively higher temperatures between 160 and 215°C. The x‐ray diffraction patterns exhibited several new reflections which made it possible to determine the unit cell. It has been found that cellulose triacetate II has four cellobiose acetate residues in a pseudo‐orthorhombic cell with a = 24.5, b = 11.56, and c = 10.43 A. Pairs of these residues are related by twofold screw axes in the c or fiber‐axis direction. The paired arrangement seems to be determined by a fitting of the natural zigzagging shape of the cellulose backbone which is exaggerated by the presence of the secondary acetyl groups. The glucose residues of such a pair are parallel and inclined at about 45° with respect to the a axis. A neighboring chain pair points in the opposite direction and the median planes of the cellobiose units of two such pairs are approximately mutually perpendicular. To accommodate this type of packing, one half of the primary acetyl groups must be twisted sharply out of the median plane of the parent glucose residues. A second statistical model which basically is very similar is also considered. There do not appear to be any strong interactions between chains.
Anionic polymerization of α‐methylstyrene
Authors: Worsfold D. J. , Bywater S.
Published: April 2003

The polymerization of α‐methylstyrene catalyzed by sodium naphthalene has been studied below 0°. Measurable amounts of monomer remained in equilibrium with the polymer down to −40°, even though the color indicated that active chain ends were still present. This behavior is expected of α‐methylstyrene since, due to a low heat of polymerization, the reverse of the chain propagation step must be important at these temperatures. From the equilibrium monomer concentrations determined experimentally, the heat and entropy of polymerization of α‐methylstyrene has been calculated.
An improvement in the graphic treatment of angular light scattering data
Authors: Yang Jen Tsi
Published: April 2003

The well‐known Zimm plot can be modified by plotting Kc/Rϑ sin2 (ϑ/2) against 1/sin2 (ϑ/2) with concentration c as a parameter, which gives a series of straight lines with a common intercept. By extrapolating to zero concentration one can determine the weight‐average molecular weight from the reciprocal of the slope and the radius of gyration from the common intercept on the ordinate. This method finds applications for macromolecules having very high molecular weights.
CH2 rocking vibrations of polyethylene glycols
Authors: Kuroda Yoko , Kubo Masaji
Published: April 2003

Measurements were made of the infrared absorptions of ethylene glycol and polyethylene glycols (from a dimer to a heptamer) in liquid state. In the case of polyethylene glycols, three distinct peaks appear in the wave number range of CH2 rocking modes. This affords a conclusive evidence in support of the existence of the trans form as well as the gauche form of the O(CH2)2O portion of linear chains. This confirms the result of dipole moment measurements that both gauche and trans forms are realized in the configurations of the lower members of polyethylene glycols in solution. Although it is reported that high molecular polyethylene glycol in crystalline state assumes a highly crumpled helical structure resulting from the gauche minima, the molecular structure of low molecular polyethylene glycols is not restricted to the same helical configuration. These chain molecules take a more or less irregular form resulting from the trans and gauche minima of the internal rotation about single bonds. Ethylene glycol shows only two absorption peaks in the wave number range of CH2 rocking modes. A plausible explanation is presented based on the formation of intramolecular hydrogen bonds.
Controlled boron trifluoride catalysis of epoxy polymerizations
Authors: Wagner Herman B.
Published: April 2003

A new technique which permits of the use of boron‐trifluoride for catalysis of epoxy polymerizations is described. The destructive exotherm that ordinarily accompanies contact of this substance with epoxy compounds is avoided by gradual release of the catalyst. This controlled release is accomplished through use of the catalyst in the form of the liquid boron trifluoride‐ethyl ether complex absorbed on a particulate carrier, the component particles being coated with a paraffin barrier layer. Employing this catalyst system a smooth but rapid reaction is obtained starting with all reactants initially at room temperature and without application of external heat. Polymerization is essentially complete within several minutes following addition of the catalyst system.
Molecular distributions in polycondensations involving unlike reactants. I. Gelation
Authors: Case Leslie C.
Published: April 2003

A general criterion for gelation in polycondensations having like groups of unequal reactivity has been formulated. In its simplest form, the criterion is that, for gelation, the expectation that a given structure will be propagated is unity, or greater. Several specific cases are treated, and literal expressions relating the gelation point to the reaction probabilities are derived. Included are treatments of systems involving anhydrides and mixtures of acids and glycols. The manner in which kinetic calculations may be used to determine reaction probabilities is summarized. It is found that the inclusion of unsymmetrical reactants significantly increases the degree of polymerization necessary for gelation. However, when anhydrides are used, depending on the relative reaction rates of the anhydride and the acid formed when the anhydride reacts, the degree of reaction necessary for gelation may be either greater or less than that for a similar system using only symmetrical reactants.
An equation for calculating the number of chain scissions in the photochemical degradation of solid polymers
Authors: Flynn Joseph H.
Published: April 2003

An equation is developed for calculating the fractures/chain link from the change in weight‐average molecular weight for the case of the photochemical degradation of a polymer with an initial random molecular weight distribution. From calculations made on the degradation of cellulose with 2537 A. light, it appears that the formation of aldehyde groups and the evolution of hydrogen are in part due to reactions not involving chain scission.
Crosslink density in polybutadiene
Authors: Howland L. H. , Nisonoff A. , Dannals L. E. , Chambers V. S.
Published: April 2003

The crosslink density in polybutadiene has been determined by measurement of the polymer molecular weight by osmometry and the primary chain molecular weight by modifier analysis involving radioactive materials. Since the number of polymer molecules is equal to the number of primary chains less the number of crosslinkages, the experimental measurements may be used to calculated the crosslink density. This method can be used to determine crosslink density at a combination of conversions, modifier loadings, and polymerization temperatures which could not be done by other methods. Branching and cyclic structure forming crosslinks are not measured by this method, the principal assumption of which is that one and only one modifier fragment is attached to each primary chain. Initiation and termination processes tend to reduce the validity of this assumption, but these have been minimized by reduction of the amounts of initiator and found insignificant by comparison of different systems. Modifiers which react with polymer in nonterminal positions also reduce the validity so that primary dodecyl mercaptan was not satisfactory as a modifier in this work, while tertiary alkyl mercaptans were. Also, diisopropyl xanthogen disulfide was not satisfactory because of secondary reactions. The crosslink density of polybutadiene prepared in emulsion decreases with decreasing polymerization temperature. At a given molecular weight, the crosslink density does not appear to be a function of conversion within the range studied. At a given polymerization temperature, increasing polymer number average molecular weight was accompanied by increasing crosslink density although the rate of such increase was smaller at subfreezing polymerization temperatures. These results agree with kinetic theory of crosslinking in emulsion polymerization, but actual values are higher than those obtained in comparable systems by the gel point method.
X‐Ray diffraction pattern of a vinylidene cyanide/vinyl acetate copolymer
Authors: Yanko John A. , Hawthorne Anthony , Born John W.
Published: April 2003

A film, prepared from the copolymer of vinylidene cyanide/vinyl acetate, was stretched at 145°C. in a silicone oil bath using a draw ratio of one to three. The x‐ray diffraction data indicated that some orientation had occurred during the stretching process. In the stretched film the copolymer chains are separated by a distance of 5.86 A. This lateral chain spacing lies between those values reported for Orlon and polyvinyl acetate. Along the fiber axis of the vinylidene cyanide/vinyl acetate copolymer film, a high degree of disorder exists. As the temperature of stretching decreased from 165 to 145°C., the degree of orientation increased slightly. Amorphous patterns were observed for the films which were stretched in air immediately after being removed from oil baths at 187 and 220°C.
Chromatographic adsorption of polystyrene
Authors: Yeh Si Jung , Frisch H. L.
Published: April 2003

The fractionation of polystyrene by adsorption column chromatography has been investigated at room temperature. The adsorbent used was activated carbon suspended on Celite. The experiments were carried out on mixtures of characterized polystyrene fractions using MEK (a poor solvent), toluene (a better solvent), and tetralin (a good solvent) as eluents. It was found that; (1) the better the solvent, the higher the molecular weight portion which can be eluted out; (2) the better the solvent, the greater the total amount of the polymer which can be recovered from the column; (3) the lower molecular weight homologs are eluted out before the higher molecular weight homologs; (4) by controlling certain factors, e.g., the moisture, the chromatograms obtained were satisfactorily reproducible in detail. By using successively MEK, toluene, and Tetralin, polystyrene can be fractionated in a single passage through a column with about 80% total recovery of the polymer on the column. Optimum fractionation in a single passage is obtained by eluting with appropriate mixtures of the above solvents in order of increasing solvent power of the mixture to the polymer. These results correlate with existing information on the adsorption of polystyrene from solution.
Sorption and diffusion in ethyl cellulose. Part III. Comparison between ethyl cellulose and rubber
Authors: Barrer R. M. , Barrie J. A. , Slater J.
Published: April 2003

Sorption and diffusion of C4 and C5 hydrocarbons have been studied in thin films of ethyl cellulose in the temperature range 30 to 80°C. Only regions of low penetrant concentration were chosen in order to minimize hysteresis effects associated with slow relaxation of polymer chains. The data have been quantitatively compared with those for the same penetrants in rubber, since ethyl cellulose and rubber are examples of stiff and flexible chain polymers, respectively. In both solution and diffusion some major differences were found between the two types of medium. In rubber the heats of dilution were small and the corresponding positive entropies close to those predicted by the lattice theory of solutions. On the other hand, in ethyl cellulose at low penetrant concentrations the heats of dilution were strongly exothermal and the entropies negative. For both polymers diffusion coefficients of penetrants were dependent upon concentration, but whereas in rubber this concentration dependent decreased rapidly with rising temperature, in ethyl cellulose it was largely independent of temperature. Energy barriers involved in each unit diffusion process were comparable for a given hydrocarbon in rubber and in ethyl cellulose, while the molecular shape of the penetrant molecule substantially influenced the diffusion coefficients in each polymer. Further interpretation of the diffusion coefficients suggested that the involvement of polymer chains in each unit diffusion is much less for ethyl cellulose than for rubber. Explanations are offered, based upon the nature of the chains composing the two media and upon the existence of holes in the ethyl cellulose network, for the essential differences indicated above. The relative efficiency of ethyl cellulose and rubber membranes for gas separation is discussed.
Polymers and copolymers of sodium ethylenesulfonate
Authors: Breslow David S. , Kutner Abraham
Published: April 2003

Sodium ethylenesulfonate polymerizes readily in aqueous solution under the influence of ultraviolet light or in the presence of peroxide catalysts. The most important variable in the polymerization has been found to be the concentration of monomer, increased concentration leading to more rapid polymerization and higher molecular weights. Poly(sodium ethylenesulfonate) has been isolated as a brittle, white solid with weight‐average molecular weights as high as 150,000. Sodium ethylenesulfonate copolymerizes with a variety of water‐soluble monomers: acrylamide, acrylic and methacrylic acids, and their sodium salts. Although copolymerization occurs, water‐soluble copolymers of sodium ethylenesulfonate with acrylonitrile and with methyl acrylate could not be prepared. Water‐soluble copolymers of sodium ethylenesulfonate with vinyl acetate and with vinyl chloride have been made, but they contain only small amounts of acetate and chloride. No copolymers could be prepared with butadiene, isobutylene, styrene, α‐methylstyrene, n‐butyl vinyl ether, allyl alcohol, N‐allylacetamide, maleic acid, or fumaric acid. The copolymerization of sodium ethylenesulfonate with acrylamide and with sodium acrylate has been used to calculate reactivity ratios. From these, sodium ethylenesulfonate has been calculated to have a Q value of 0.19 and an e value of +1.51.
Studies on straining of high polymer solids
Authors: Ito Katsuhiko
Published: April 2003

Straining of high polymer solids is experimentally investigated from the standpoint of internal molecular structure. The test specimens used are epoxy cast resins as network polymers and hard polyvinylchloride as linear polymers. The experiment is mainly performed in compression. It is proved that the straining of network polymers is due solely to intramolecular micro‐Brownian motion, named “deformation strain,” and is not true plastic strain, even though strain may be frozen by secondary bonding forces at room temperatures. On the other hand, intermolecular macro‐Brownian motion, named “flow strain,” is further added for the straining of linear polymers. The mutual relations between flow strain and deformation strain on hard polyvinyl chloride are examined under various conditions, such as working and annealing temperature, magnitude of worked strain, rate of strain, etc. The plastic working ability of high polymer solids is discussed in relation to working temperature.
Determination of constants in the intrinsic viscosity–molecular weight equation
Authors: Sharples A. , Major H. M.
Published: April 2003

In the modified Staudinger equation, [η] = Km[Mv]α, the constants Km and α are usually found from measurements of [η] and Mv. As the latter cannot be determined directly, the method adopted in the past has been to prepare fractions, determine Mn or Mw by such absolute methods as osmometry and light scattering, and then to assume that the fractions are sufficiently monodisperse to justify writing Mv = Mn = Mw. An alternative approach has been suggested in this paper, making use of the fact that, for a distribution arising from random degradation, Mv = constant × Mn; it has been shown that the appropriate distribution results from the heterogeneous hydrolysis of cotton. The method has been applied to the case of cellulose triacetate in chloroform and the following results have been obtained: Km = 2.51 × 10−4; α = 1.02.