bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorine‐containing polymers. I. Copolymers of perfluoro‐olefins
Authors: Adams R. M. , Bovey F. A. 
Published: April 2003

AbstractWe have studied the copolymerization behavior of perfluoropropene, perfluorobutene‐1, perfluorobutene‐2, perfluoroisobutene, perfluoropentene‐1, and perfluorononene‐1. We have so far not succeeded in homopolymerizing these olefins. However, certain nonfluorinated, nonconjugated comonomers–ethylene, vinyl. chloride, vinyl acetate, and the vinyl alkyl ethers–were found to copolymerize readily, giving copolymers containing up to 50 mole per cent, and in some cases slightly more than this, of the perfluoro‐olefin in the copolymer. The higher members of the series copolymerize in general less readily than the lower members. The products ranged from viscous oils to tough, film‐forming solids. The difficulty of homopolymerization and the relative ease of copolymerization of the perfluoro‐olefins with the above comonomers are discussed and interpreted in terms of probable electron distributions around the double‐bond.
Polymerizable derivatives of long‐chain fatty acids. VII. Copolymerization of vinyl acetate with some long‐chain vinyl esters
Authors: Port William S. , Jordan E. F. , Hansen John E. , Swern Daniel 
Published: April 2003

AbstractA study was made of the copolymerization of vinyl acetate with vinyl palmitate, vinyl stearate, and vinyl oleate, respectively, True copolymerization was shown to have occurred on the basis of the solubility characteristics of the crude copolymers over a wide range of compositions. The monomer reactivity ratios for the comonomers vinyl palmitate (r1) and vinyl acetate (r2) were determined by two methods. One, based on an analysis of the copolymer, gave r1 = 0.78 ± 0.10 and r2 = 1.15 ± 0.13; the other, based on an analysis for each monomer in the mixture remaining after polymerization, gave r1 = 0.66 ± 0.07 and r2 = 0.84 ± 0.10. When the vinyl palmitate or vinyl stearate content of the copolymer exceeded about 20–25 mole per cent, the copolymers exhibited first‐order transition points which were determined using a refractive index technique as well as a polarizing microscope method. Where no transition point could be observed, brittle point measurements were made.
Determination of the molecular weights of fractionated polyvinyl acetates by a new type of light‐scattering instrument
Authors: Bosworth P. , Masson C. R. , Melville H. W. , Peaker F. W. 
Published: April 2003

AbstractA new light‐scattering instrument is described, in which the incident light beam is rotated by a mirror system, and the photomultiplier cell (E.M.I. type 5311) which measures the scattered light remains stationary. A study of the osmotic and light‐scattering molecular weights (Mw) of a series of polyvinyl acetate fractions shows that the process of fractionation separates the several molecular species present according to both size and shape. The average dimensions of the polymer chain (D) can be deduced from the dissymmetry measurements, assuming the random chain model. These results show that the most insoluble fraction has the highest molecular weight, but is also the least extended in solution. The lower‐molecular‐weight samples are relatively longer. The ratio Mw/D2 is a measure of the degree of branching of the polymer chain, and the minimum value measured for ten samples is 0.5. This is believed to be the value characteristic of the linear molecule. A photopolymer prepared at −25°C. and low conversion, that is, under conditions favoring the formation of linear polyvinyl acetate molecules, also had this same minimum value of Mw/D2 = 0.5.
Étude expèrimentale de la lumière diffusée par des bâtonnets anisotropes
Authors: Horn P. , Benoit H. 
Published: April 2003

AbstractNous avons appliaué à l'étude de suspensions de virus de la mosaïque du tabac les résultats de la théorie de la diffusion par des bâtonnets anisotropes. Dans ce but on détermine d'abord l'anisotropie δ du bâtonnet en extrapolant à angle de diffusion nul le facteur de dépolarisation ρv. On trouve ainsi δ = 0,3, valeur un peu forte comparée à celle déduite des expériences de biréfringence d'écoulement (δ = +0,1). Enfin comparant les répartitions angulaires des différentes composantes avec la courbe théorique, on obtient un accord trés satisfaisant en prenant pour longueur des bâtonnets L = 2300 Å, ce qui constitue un bonne vérification de la théorie précitée.La même analyse appliquée à l'acide thymonucleique S VIII préparé par Schwander en solution NaCl 1M neutre conduit aux valeurs:
Copolymerization of vinylsulfonic acid derivatives with butadiene
Authors: Marvel C. S. , Menikheim V. C. , Inskip H. K. , Taft W. K. , Labbe B. G. 
Published: April 2003

AbstractCopolymers of vinylsulfonic acid derivatives with butadiene, isoprene, and styrene have been prepared. The evaluation of butadiene‐vinylsulfonic acid ester copolymers indicates that these rubbers have good low‐temperature characteristics and that the stress‐strain properties of the n‐butyl vinylsulfonate copolymer approach those of the standard GR‐S rubber; however the oil resistance properties are poor. The stress‐strain properties of the butadiene‐n‐hexyl vinylsulfonate copolymer are inferior to those of the n‐butyl analog.
Role of depropagation reactions in the copolymerization of styrene and sulfur dioxide
Authors: Barb W. G. 
Published: April 2003

AbstractThe rate of reaction of sulfur dioxide in styrene solutions at 60°C., with azodiisobutyronitrile as thermal catalyst, has been measured: (1) by gravimetric determination of the total rate of polymerization and analysis of the polymer formed and (2) volumetrically. An experimental arrangement for the latter method, which can be used when the partial pressure of the solvent (styrene solution) is appreciable compared to that of the solute (sulfur dioxide) is described. The kinetics of reaction conform to the mechanism previously proposed, according to which sulfur dioxide reacts in the form of a 1/1 styrene/sulfur dioxide complex C. It is shown that certain features attributable to depropagation reactions, such as the increase in the styrene content of the copolymer with decreasing styrene concentration in the reaction mixture, are much more marked at 60°C than at 20°C. By combining the rate measurements with new data on the temperature dependence of copolymer composition at elevated temperatures, it is possible to assign an approximate value to the velocity constant of a depropagation reaction involving breakage of a carbon‐sulfur bond. The activation energy is estimated at 50 to 62 kJ. (12 to 15 kcals.), which is much lower than that for depropagation of a vinyl polymer; the frequency factor is about 4 X 1010 to 3 X 1012sec.−1. Some data on the composition of polymers prepared at 0° and −20°C. are appended. It is shown that the C· + C propagation step, which seems negligible at 20°C. or above, becomes of some significance at lower temperatures. Under these conditions polymers containing less than two styrene units per sulfur dioxide can be prepared.
Spaltung des fibrinmoleküls mittels cupriäthylendiamin
Authors: Schauenstein E. , Hochenegger M. 
Published: April 2003

AbstractDie Untersuchungen ergaben, dass beim Fibrin‐Molekül von einer kontinuierlichen Verteilung der aromatischen Aminosäuren im allgemeinen nicht gesprochen werden kann. Die Einwirkung von Cupriäthylendiamin auf Fibrin führt zu einem Zerfall des Teilchens in zwei Fraktionen “I” und “II”. Fraktion I macht etwa 75% des Moleküls aus, ist stabil, unlöslich in NaCl‐Lösung, enthält das gesamte Tyrosin des Fibrinmoleküls sowie 3% Tryptophan. Obwohl diese Fraktion noch deutlich die Eigenschaften eines hochpolymeren Eiweisskörpers zeigt, kann sie durch Thrombin nicht mehr fibrillär polymerisieren. Fraktion II dagegen macht rund 15% des Fibrins aus, ist labil, löslich in NaCl‐Lösung, enthält kein Tyrosin, jedoch ebenfalls 3% Tryptophan, wahrscheinlich viel mehr Arginin als Fraktion I und trägt den Charakter eines Proteids.
Intrinsic viscosity‐molecular weight relationships for dextran
Authors: Wales M. , Marshall P. A. , Weissberg S. G. 
Published: April 2003

AbstractIntrinsic viscosities of dextrans of known branching ratio were measured in water formamide, and in a water‐methanol mixture at two temperatures. Weight‐average molecular weights (sedimentation equilibrium) ranged from 1.1 × 104 to 1.7 × 106. A model for the hydrolyzed dextran molecule was assumed. Using the methods of Zimm and Stockmayer, the g factor calculated from this model was compared with the g factor obtained from the intrinsic viscosity‐molecular weight data through the use of the Flory‐Fox theory (g = ratio of squares of radii of gyration of branched to unbranched polymer). The calculated branch lengths required to make consistent the g factors obtained by two different routes were of the same order of magnitude as those found by classical organic chemical methods for other dextran preparations. The intrinsic viscosity‐molecular weight relation at 25°C. in water for linear dextran was predicted from the data. It is suggested that investigations of branched polymers of known constitution be carried out by these methods.
Determination of the rheological properties of fluids by an electronic method
Authors: Thickens R. W. 
Published: April 2003

AbstractIt has long been known that a single point determination can not describe the rheological properties of a fluid. A new method applicable to nonconducting fluids with viscosities ranging from a few hundred to more than 15,000 poises is described. The method consists of a cup and ball in which the ball is forced into rather than pulled out of the cup. Viscosity is measured electronically as a function of the time required for the ball to move a predetermined distance under a given load. Shear rates are variable over very large ranges. Rheological studies were made of a blown castor oil, three polyisobutylenes, and a high viscosity polystyrene. In addition certain physical properties of polyisobutylenes are presented.
Diffusion moléculaire de la lumière: Les constantes de lord rayleigh des liquides étalons
Authors: Rousset A. , Lochet R. 
Published: April 2003

AbstractUne revue des déterrninations des constantes de Rayleigh pour les liquides montre qu'un nombre appréciable de chercheurs différents arrivent è des réultats concordants en utilisant des m6thodes photographiques; ces rèultats sont considCablement plus bas que ceux de Carr et Zimm et que ceux prévus par la thérie. Le premier groupe de rbultats confirme des considérations thériques modifiées, mais ni ces réultats ni la dbtermination des poi& moléculahes n'apportent de confirmation de la valeur absolue de la constante de Rayleigh. Les auteurs recommandent l'adoption des valeurs déterminks photographiquement.
Infrared examination of various polyisoprenes
Authors: Richardson W. S. , Sacher A. 
Published: April 2003

AbstractThe infrared spectra of synthetic polyisoprenes have been used to obtain quantitative analyses for the various types of addition occurring in the polymers. It is found that the composition of polymers prepared in bulk and emulsion systems is, within experimental error, independent of specific catalyst and per cent conversion of monomer to polymer. The structure of these materials is affected by preparation temperature, increasing temperature leading to a slight increase in 3,4 addition and a large increase in cis 1,4 addition. Polymers prepared in solution with alfin and sodium catalysts show increased amounts of 3,4 addition at the expense of 1,4 addition. Polymers prepared with a cationic catalyst (BF3) are apparently not exclusively linear polyisoprenes.
Methacrylamide polymers and copolymers and their alkaline hydrolysis
Authors: Pinner S. H. 
Published: April 2003

AbstractNew evidence bearing on the resistance to hydrolysis of a portion of the amide groups in polymethacrylamide has been obtained through a study of methacrylic acid (M1) — methacrylamide (M2) copolymers. These copolymers were prepared in aqueous solution with potassium persulfate catalyst. The reactivity ratios were found to be approximately r1 = 2.0, r2 = 0.3. The ratio of accessible amide nitrogen to total nitrogen was determined for each copolymer and was found to vary from 62.3% for polymethacrylamide to 4.3% for a copolymer containing 4.2 mole % of the amide. Some calculations have been made based upon a semiquantitative statistical interpretation of the suggestion of Arcus that the hydrolysis of polymethacrylamide ceases as soon as each amide group is bordered by two carboxylic ion neighbors and the agreement between observed and calculated ratios offers good support for this theory. The actual mechanism of stabilization by the ion neighbors is still obscure but the chain‐stiffening effect of the α‐methyl groups is believed to play an important role.
Relation between stress relaxation and aging resistance of rubber vulcanizates. II. Effect of copper in various accelerated stocks
Authors: Pedersen H. Leth 
Published: April 2003

AbstractSome details for the construction of a modulus balance and thermostat are discussed. A new dumbbell type is developed for aging tests. In four stocks containing different accelerators, the function of copper applied as stearate is investigated. In the case of Santocure, a comparatively high sensitivity is found, and the t1/2 (TB) value for aging at 70°C. represents a sensitive measure of the prooxygenic effect, whereas relaxation times at 121° showed a smaller but definite variation. With MBT boosted with DPG only a limited effect was observed. Conversely, for the thiurams, copper addition produced a marked antioxidant effect comparable with the retardation normally effected by 2PHR of ordinary antioxidants. 0.05% copper showed an antioxidant activity equivalent to the 2PHR antioxidant. Consistent results were obtained for aging, relaxation, and rate of oxidation. The factors of retardation as might be expected, however, are not quite comparable. The factor of retardation for copper alone is 4–8 units. The copper develops in the thiuram vulcanizates a strong brown color giving colored solutions upon extraction with acetone and iso‐octane. As the spectrophotometric determination of the colored complex is difficult, owing to the presence of the strong absorbing ZDC, the nature of the colored complex has not yet been ascertained, but it must somehow be responsible for the inverted action of copper found here.
The structure of branched polymers of diallyl phthalate
Authors: Simpson W. , Holt T. , Zetie R. J. 
Published: April 2003

AbstractThe complete characterization of a branched polymer involves many factors, the most difficult to assess being the average number of elementary linear portions, or branches, of which the polymer is composed, the degree of polymerization of the branches and the extent of cyclic structure formation. A method of analysis of branched polymers is proposed which should be applicable to polymers of any polyfunctional monomer the unsaturated groups of which are separated by saponifiable links. The method is based on the measurement of degree of polymerization and residual unsaturation of the polymer followed by saponification and determination of degree of polymerization of the resulting polymer, and involves the assumptions that branching in the polymer occurs only by the sharing of a monomer unit by two or more linear portions or branches depending on the number of double bonds in the monomer and also that the average degree of polymerization of the branches remains unchanged by the saponification treatment. Evidence from experiments on the saponification and re‐esterification of poly(allyl acetate) and poly(allyl benzoate) indicates, that, in the case of diallyl esters, the above conditions are satisfied. The technique was therefore applied to three polymers of diallyl phthalate, and in each case the average number of chains and degree of polymerization of the chains were estimated. Evidence of considerable extents of cyclic structure formation was found, each individual branch in the polymers consisting of approximately fourteen diallyl phthalate units, six of which are doubly reacted. It is suggested that the existence of extensive formation of cyclic structures may be partly responsible for the poor correlation of predicted with actual degrees of conversion at gelation in polymerizations involving multifunctional monomers.
Notes on the statistics of polymer chains
Authors: Ullman R. , Hermans J. J. 
Published: April 2003

AbstractThe configurations of flexible macromolecules are discussed with particular emphasis on some problems arising in the theory of the volume effect. The main points considered are: (1) the relationship between the Kuhn statistical chain element and the carbon bond length; (2) the assumption that a polymer chain is equivalent to a collection of independent beads normally distributed with respect to the center of gravity (“Gaussian gas” model); (3) the distribution of segments of a polymer chain with respect to the center of gravity; (4) the theory of the execluded volume for plane models of a polymer molecule; (5) the relationship between the excluded volume and the local density of polymer segments; (6) the influence of the solvent on the excluded volume; (7) polymer configurations and viscosity.
Redox recipes. IX. Alkaline nitroprusside‐hydroperoxide recipes
Authors: Kolthoff I. M. , Meehan E. J. 
Published: April 2003

AbstractRedox recipes containing nitroprusside are described for the emulsion copolymerization of butadiene (75)‐styrene(25). Approximately 65% conversion is reached in 8 hours at 25° with a recipe containing 5 parts of fatty acid soap, 0.3 part of sodium nitroprusside dihydrate, 0.1 part of hydroxylamine hydrochloride, 0.1 part of diisopropylbenzene hydroperoxide, 0.5 part of n‐dodecyl mercaptan, and 0.5 part of potassium chloride per 180 parts of water and 100 parts of monomers. If alkali is added to the polymerization system the polymerization is accelerated markedly and the addition of 0.1 part of hydroxylamine does not affect the rate. Approximately 60% conversion is reached in 12 hours at 5°C. with a recipe similar to that given above, but without hydroxylamine, provided that the aqueous phase is 0.01 M in trisodium phosphate or alkali hydroxide. From the effect of various factors upon the rate of conversion it is postulated that in the low temperature recipe (with added alkali) the initiation occurs by RO · radicals:
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In the recipe without added alkali but with hydroxylamine hydrochloride the initiation apparently occurs by RS · radicals (RSH is mercaptan) formed by interaction of the oxidation product of nitroprusside with primary mercaptan.
Effect of nonterminal monomer units on the reactivity of polymeric free radicals
Authors: Barb W. G. 
Published: April 2003

AbstractCertain abnormalities in the compositional relationship of styrene/maleic anhydride copolymers indicate that nonterminal monomer units in a polymer radical (principally the penultimate unit) can detectably influence radical reactivity, through electrostatic interactions with reacting monomer molecules. This effect should be particularly pronounced for monomers of type CHXCHX, where X is a dipole. Several examples from the literature are cited to show that abnormal dependences of copolymer composition on monomer concentration ratio can be explained along these lines. It is suggested that the recently observed variation of cross‐termination velocity coefficients with composition of the monomer mixture is attributable to a similar cause.
Copolymers of 2‐vinylpyridine, methyl acrylate, and dichlorostyrene: Polymerization and properties in solution
Authors: Aggarwal Sundar L. , Long F. A. 
Published: April 2003

AbstractCopolymerization studies have been made on the three two‐component systems formed by the monomers methyl acrylate, 2‐vinylpyridine, and dichlorostyrene, and values of the monomer reactivity ratios were determined. Terpolymers were prepared from mixtures of these same monomers, and their compositions were compared with those predicted from the kinetic data for the copolymerizations. Measurements of dissymmetry of scattered light, molecular weight, and viscosity were made on solutions in acetic acid and in methyl ethyl ketone of a terpolymer containing 37 mole per cent methyl acrylate, 47 mole per cent 2‐vinylpyridine, and 16 mole per cent dichlorostyrene. The molecular weight of the terpolymer is essentially the same in the two solvents but the polymer chain is more extended in acetic acid than in methyl ethyl ketone. In nitromethane solutions of the terpolymer the ηsp/c values increase sharply with decreasing concentration. This increase is eliminated if the solutions also contain 0.01 mole per liter of a substituted quaternary ammonium iodide. These facts indicate that the polymer behaves as a polyelectrolyte in nitromethane, presumably because of reaction between the aci‐form of the solvent and the vinylpyridine groups.
Dielectric relaxation in a series of polyvinyl acetals
Authors: Sutherland T. H. , Funt B. L. 
Published: April 2003

AbstractThe dielectric properties of polyvinyl isobutyral, hexanal, and 2‐ethylhexanal have been investigated. Dielectric constants and loss factors were measured at eight frequencies between 50 and 100,000 cycles in the temperature range of 25 to 130°C. Free energies, entropies, and enthalpies of activation were calculated, using the absolute reaction rate theory. The results illustrate the effects of “internal plasticization.” With increasing complexity of the interchain substituent, the electrical relaxation time is lowered, and the free energy, entropy, and enthalpy of dielectric relaxation are also decreased. These changes offer a quantitative measure of the decrease in interchain forces. It was also noted that the normal aldehyde substituents exhibited greater plasticizing action than the branched chain secondary groups. The electrical transition temperatures were compared with independently determined softening and inflection temperatures. The electrical and mechanical determinations were in good agreement for identical samples of the polymers.