bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gelation of polyacrylic acid by divalent cations
Authors: Wall F. T. , Drenan J. W. 
Published: April 2003

Abstract“Gel point” studies involving polyacrylic acid and certain divalent ions have been carried out. As a gelation agent, barium hydroxide was found to be more effective than strontium hydroxide, which in turn was better than calcium hydroxide. This indicates that the association between inorganic cation and polyacrylate ion is not entirely a matter of coulombic charge. However, experiments involving partial replacement of barium hydroxide by barium chloride suggest that charge is still the most important factor in the bonding. The data cannot be explained upon the basis of simple ionic equilibria.
Spectrometric determination of refractive index at low temperatures
Authors: Wiley Richard H. , Garrett Robert R. 
Published: April 2003

AbstractA spectrometric technique for the determination of refractive indices of liquids and polymers over a temperature range of −70 to +70°C. has been developed and used to establish the absolute accuracy, within =0.0004 refractive index units, of a more convenient refractometric method previously described. Refractive index values are reported for dimethyl phthalate from + 70 to +15°C.; polyvinyl acetate from + 65 to −70°C.; and tricresyl phosphate from +30 to −80°C. The refractometric values are within =0.0004 or less units of the spectrometric values over this range. The data for tricresyl phosphate locate two apparent second order transitions at −47 and at −62°C. The higher value (−47°C.) is observed with thoroughly dried tricresyl phosphate.
The viscosities of dilute solutions of nitrocellulose
Authors: Moore W. R. 
Published: April 2003

AbstractThe viscosities of dilute solutions (0.05, 0.1, and 0.2 g. per 100 ml.) of relatively high nitrogen content nitrocelluloses, weight‐average molecular weights ca. 100,000, have been studied using homologous series of methyl ketones, alkyl acetates, and dialkyl phthalates as solvents. The simple form of the Huggins equation,

does not appear to hold, plots of ηsp/c against c being generally curved. The results are capable of expression by

where A equals [η] and B the initial slope. Values of B and A appear to be related to solvent power as determined by the volume of hexane required to cause initial phase separation from solution, good solvents giving higher values of B and A than poor. The variation of B with solvent is more marked than that of [η] and may reflect differences in degree of coiling of chains in different solvents. Values of B/[η]2 (Huggins k′) do not generally decrease with solvent power increase. The slopes of Martin plots divided by intrinsic viscosities are not generally related to solvent power in the manner observed by Spurlin with solutions of ethyl cellulose.
General theory of deformation of viscoelastic substances
Authors: Sips R. 
Published: April 2003

AbstractThe general theory of the deformation of viscoelastic substances developed in two previous papers for the one‐dimensional case is now extended to three dimensions. The integro‐differential equations obtained are generalizations of the well‐known Navier‐Cauchy equations and, like these, only apply to small deformations.Some special cases are considered in detail and lead to interesting conclusions. In particular, the theory predicts that for incompressible high polymers, one should obtain the same creep and relaxation functions when the material is subjected to extension, torsion, or bending.
Polymerizable derivatives of long‐chain fatty acids. IV. Vinyl esters
Authors: Port William S. , Hansen John E. , Jordan E. F. , Dietz T. J. , Swern Daniel 
Published: April 2003

AbstractContrary to some published reports, the vinyl esters of saturated fatty acids polymerize readily and rapidly. Vinyl oleate, when present in excess of 5%, and oxygen exert marked retarding effects.Techniques are described for the free‐radical‐initiated polymerization of the vinyl esters of caprylic, capric, lauric, myristic, palmitic, and stearic acids in bulk, dispersion, solution, and emulsion. Some data are given for polymerization in the presence of chain‐transfer agents, such as carbon tetrachloride, dodecylmercaptan, and ethylbenzene. Conditions are reported for obtaining degrees of polymerization from about 2 (when chain‐transfer agents are employed) to 10,000 (weight average). The weight average degree of polymerization increases markedly as the conversion increases, particularly above 80%. Even up to extremely high conversions, soluble polymers are obtained in most cases.Solubility characteristics, transition point data, molecular weights (osmometric and light‐scattering), and isolation and purification techniques are also reported.
Photoinitiated free radical polymerization of vinyl compounds in aqueous solution
Authors: Evans M. G. , Santappa M. , Uri N. 
Published: April 2003

AbstractA new method for the photochemical initiation of polymerization of vinyl compounds in aqueous solution is described. The photochemically active species is an ion pair complex of the formula Fe3+X−(X− = OH−, CI−, N−3, etc.). The light absorption by the ion pair leads to an electron transfer causing reduction of the cation and oxidation of the anion to an atom or free radical X. The latter leads to the initiation of polymerization in accordance with X + CH2CHR→XCH2CHR. The kinetics of the reaction were studied by the measurement of: (a) ferrous ion formed (colorimetrically), (b) monomer disappearance (by titration and by weighting the polymer), (c) the chain length of the polymer (in the case of methyl methacrylate). The dependence of the quantum yield on the light intensity, light absorption fraction, and the concentration of vinyl monomer and ferrous ion added initially was investigated. A complete mechanism, both with regard to the formation of free radicals and the polymerization reaction, was put forward involving: (1) light absorption, (2) a primary dark back reaction, (3) dissociation of the primary product, (4) a secondary dark back reaction, (5) initiation of polymerization by free radicals, (6) propagation of polymerization, and (7) termination by recombination of active polymer endings. The mechanism was verified by the experimental results and some constant ratios were estimated quantitatively.
Spreading properties of high polymers
Authors: Saraswat H. C. , Kalyanasundaram A. 
Published: April 2003

AbstractMany linear polymers containing water‐attracting groups spread uniformly at the airwater interface. The spreading property of polymethyl methacrylate is due to the ester groups which serve as anchors and promote spreading. The spreading of polystyrene, although it is a pure hydrocarbon, appears probably to be due to the end groups in each polymer molecule, introduced at the termination of the chains which act as anchors and facilitate spreading.The surface pressure extended by the films of the high polymers is a sort of two‐dimensional swelling pressure. The distinguishing feature of these films is their high compressibility in the rectilinear portion of the F–A curve.The limiting areas for F–A curves are not independent of the concentrations of spreading solutions as might be expected. The primary cause of this phenomenon in the case of high polymers appears to be a more or less coherent sponge‐ or felt‐like structure which develops at high concentration. The linear polymers, like polystyrene, become coiled up statistically and at higher concentration the coils become interlocked and produce an imperfectly spread film.
Recherches sur la cellulose III régénérée de l'ammoniac‐cellulose
Authors: Legrand Ch. 
Published: April 2003

AbstractL'étude de la cellulose régénérée des composés de gonflement que fournissent avec NH3 liquide la cellulose native et la cellulose mercerisée conduit à la définition de deux formes correspondantes aux matières de départ: les celluloses IIIα et IIIβ. L'action de l'eau fournit avec le réseau IIIα un réseau élargi et avec IIIβ conduit à la cellulose II. Les mailles des celluloses IIIα et IIIβ toutes les deux monocliniques, présentent une petite difference.
Molecular weight distribution in polymethyl methacrylate
Authors: Harris Ivan , Miller R. G. J. 
Published: April 2003

AbstractThe Morey‐Tamblyn turbidity method has been used to investigate the molecular weight distribution in a series of polymethyl methacrylates including commercial and experimental injection moulding powders. Evidence has been obtained that the increase in rate of polymerization occuring in the polymerization of methyl methacrylate (Norrish‐Smith effect) causes widening of the distribution in high conversion polymers, but the separation into multiple peaks reported by other authors has not been observed. From an examination of specially prepared polymers, e.g., at small degrees of conversion, it is concluded that chain combination is a more likely termination process than disproportionation.
Dielectric dispersion in cellulose nitrate solutions
Authors: Scherer Philip C. , Testerman M. K. 
Published: April 2003

AbstractThe dielectric dispersion of cellulose nitrate solutions in acetone was studied over a frequency range of 100‐500 KC by a resonance method using substitution techniques to measure the capacitance. An abnormally narrow region of dispersion was found which could not be reconciled with the Debye type of absorption. By assuming the solvated chain molecule to have the form of a loosely held random coil it was possible to explain the experimental, dispersion curve on the basis of resonance absorption.Speculation on the similarity of the shape of the dispersion curves to those found for distribution by fractional precipitation suggested a possible correlation between them. In the case of at least one polymer the derived correlation proved satisfactory.
Polymerization of acetaldehyde and crotonaldehyde catalyzed by aliphatic tertiary amines
Authors: Degering Ed. F. , Stoudt T. 
Published: April 2003

AbstractAcetaldehyde was condensed with acetaldol using triethylamine as the catalyst. The reaction products of the branch‐chained type were found to predominate. Acetaldehyde was polymerized by trimethylamine, triethylamine, tri‐n‐propylamine, and tri‐n‐amylamine to resinous materials possessing desirable film‐forming properties. Crotonaldehyde was polymerized by triethylamine to a resin similar in all respects to the product of acetaldehyde produced under similar conditions.
Propriétés comparées des polyamides n‐n′ et des polyamides 1‐n
Authors: Cannepin A. , Champetier G. , Parisot A. 
Published: April 2003

AbstractD'autres travaux sont encore à effectuer pour permettre un choix certain entre ces trois hypothèses. Les faits expérimentaux montrent cependant que, s'il existe une grande ressemblance entre les polyamides n‐n′ et 1‐n′, ces derniers presentent des particularités qui permettent de supposer que leur structure spatiale peut differer de celle des polyamides n‐n′. Plus précisément, il est possible d'admettre l'existance dans ces composés, de forces d'interactions hydrogène d'ordre bifurque, que la proximité des groupements CONH amplifie. Cela se traduit par une élévation anormale du point de fusion de ces composes qui les met à part dans la hiérarchie des polyamides normaux.Il faut signaler cependant que ces conclusions ne peuvent, en l'état de la question, ětre absolues, et qu'il y a lieu de ne pas négliger la possibilité de l'existence de ponts de covalence interchaînes qui rapprocheraient alors les polyamides 1‐n des résines uréeformol plutôt que des Nylons.
Statistical thermodynamics of solutions of low molecular weight polystyrenes
Authors: Tompa H. 
Published: April 2003

AbstractThe lowering of the vapor pressure of the solvent in solutions of low molecular weight polystyrenes in benzene and in toluene was measured by a differential manometer. Heats of dilution of the same solutions were measured in a small calorimeter. The calorimeter had been designed in such a way that there was no vapor space above the solution and above the solvent. The activity of the solvent as a function of concentration can be represented either by Orr and by Guggenheim's formulas, using site fractions, or by Huggins' and by Flory's formula, using volume fractions, but only in the latter case is the interaction constant μ independent of the solvent, and only slightly dependent on chain length. Heat is always evolved on dilution and can be represented by a van Laar type of expression. The partial molar entropy of mixing of the solvent comes out very near to its value in an ideal solution. No satisfactory explanation can be given in terms of current statistical theories based on the lattice model.
On ionic copolymerization
Authors: Landler Yvan 
Published: April 2003

Abstract
The reactivity of monomers in an ionic copolymerization is shown to be a function of the polarity of the substituent on the ethylenic double bond.
The nonalternating tendency is explained by the absence of an alternating polar effect during the propagation step.
The results seem to indicate in the case of the monomers studied here the absence of any other selective effects (e.g., steric) and furthermore that the reactivity of the carbonium ions derived from these different monomers is the same. Therefore it is suggested that:
The original Wall equation, dM1/dM2 = α(M1/M2) may be applied.
Absolute propagation rates in emulsion polymerization I. Butadiene in mutual system
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 Mutual Recipe, 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. It was found, as expected, that the number of particles formed is a function of the temperature of initiation, almost doubling in number for a 10°C. rise in temperature. This number is also a function of the soap charge, being approximately proportional to the square root of the soap concentration. Unlike the case of styrene polymerization, the rate of polymerization per particle was found to be affected by the amount of soap adsorbed on the particle, hence it cannot be considered as representing the true propagation rate for butadiene. However, the rate of polymerization, when calculated per mole of soap present, was found to be a function of temperature only, yielding an activation energy value of ca. 14 kcal.
Statistics of linear macromolecules with a relatively short chain. IV. Molecular dimensions from viscosity and sedimentation
Authors: Peterlin A. 
Published: April 2003

AbstractIn the usual model of linear macromolecules the number of chain links, Z, is so assumed that in the calculation only the highest term in Z need be considered. This is correct if Z is infinite, and holds fairly well in the soft, flexible molecules, but fails completely in the stiffer ones—like cellulose—even for molecular weights of some hundred thousands. With the exact values for the effective distance of the chain elements the theory of the sedimentation constant and of the intrinsic viscosity yield results which fit the experiments much better than could be achieved by the simple theory of the infinite chain. In plotting log (M/[η]) and log [s] versus log M, a pair of the characteristic parameters α and a/b can be determined from the experiments. Since α = cos β is the mean cosine between two consecutive links, it measures the stiffness of the macromolecule. In the second parameter a is the hydrodynamic radius and b the length of the chain unit. The values for cellulose acetate in acetone are in good agreement with our knowledge about the cellulose.
The hofmann reaction with polymethacrylamide
Authors: Arcus C. L. 
Published: April 2003

AbstractThe reaction of polymethacrylamide, [‐CH2C(CH3)(CONH2)‐]n, in aqueous solution with hypobromite and hypochlorite has been investigated. Different reaction procedures yielded polymers which were similar, and which contained a small number of primary amino groups, considerable carboxyl and unreacted amide groups and, probably, alkylacylurea groups formed by interaction between adjacent isocyanate and halogenoamide groups. Analytical data supporting these conclusions are presented. The polymer from the Hofmann reaction is soluble in dilute alkali and also in strongly acid media, precipitating on dilution. Methacrylamide monomer reacts with hypochlorite to give N‐α‐methylvinyl‐N′‐methacrylurea and acetone.
Amide interchange reactions
Authors: Beste L. F. , Houtz R. C. 
Published: April 2003

Abstract(1) Sebacamide and N,N′‐diacetylhexamethylenediamine interchange to produce acetamide and polyhexamethylene sebacamide. (2) The rate is proportional to the concentrations of the two reacting species and to the square root of carboxyl group concentration. (3) The rate increases with increasing concentration of water. Reagents which had been held in the molten state under high vacuum were still capable of reaction. (4) N‐Substitution decreases the rate constant; the isobutyl group is more effective than methyl in this respect. (5) As an indication of the amount of interchange occurring during a typical polymerization, it is computed that at least 42% of the amide links interchange during the 66 nylon synthesis. This means that it is not feasible to make nonrandom copolyamides by polymerizing together low molecular weight homopolyamides. Interchange does provide for the production of nonrandom copolymers from two or more high molecular weight homopolyamides.
Molecular weight degradation of polyvinyl acetate on hydrolysis
Authors: Wheeler O. L. , Ernst S. L. , Crozier R. N. 
Published: April 2003

AbstractWhen the acetate groups of polyvinyl acetate are removed and subsequently restored, the viscosity of the polymer is usually decreased. It is found that after such processing, vinyl acetate polymers prepared at a given temperature approach a maximum viscosity regardless of the viscosity of the original resins. This maximum is increased by lowering the temperature of polymerization and is different for other vinyl esters. The extent of degradation is negligible at low conversions. It is concluded that this phenomenon is characteristic of the monomer. The chemical bond responsible for the degradation has many of the properties of ester linkages. The resins degrade with both bases and acids although the latter catalyst sometimes requires the presence of water. They also degrade when heated in a solution of pyridine, acetic acid and acetic anhydride. The extent of degradation closely parallels the degree of hydrolysis. It is suggested that these ester linkages are formed during polymerization as a result of transfer with the carbon‐hydrogen bonds of the acetate groups of both monomer and polymer. Evidence of another transfer reaction involving the vinyl group, but having no bearing on the degradation, is also advanced. If polyvinyl acetate is alcoholized with an acid catalyst, in the absence of water, the processed resin may have a higher viscosity than would be the case with an alkaline catalyst. How much higher is governed by the type of initiator used in the polymerization. This suggests that polymer molecules may be united under these conditions, but the nature of the reaction is obscure.
The fibrillate structure of natural cellulose
Authors: Hock Charles W. 
Published: April 2003

AbstractInterpretations of the small‐scale structure of natural cellulose have been greatly influenced by information obtained from x‐ray diffraction studies. This work has given rise to a structural model, according to which there are some regions of cellulose in which the molecules are highly ordered (crystalline) and other regions in which there is considerable disorder (amorphous). This interpretation does not, however, adequately emphasize the fibrillate character of natural cellulose‐a structure which, as the result of light and electron microscope investigations, is well established. Since many reactions proceed more readily in the interfibrillar regions than in the fibrils themselves, it seems that the cellulose molecules in the fibrils, in contrast to those in the interfibrillar regions, are more highly ordered. Intensive treatments, such as acid hydrolysis, may cause a further breakdown whereby the fibrils are split transversely into small rodshaped particles, but the comparatively greater ease with which fibrillation occurs following a variety of degradative reactions suggests that the ordered character of the fibrils along the long axis is not interrupted by regions of the same magnitude and extent of disorder as those which occur between the fibrils. Although x‐ray diffraction diagrams of cellulose have generally been considered to indicate the presence of small elongated regions of highly crystalline cellulose, i.e., micelles, it would be equally consistent to suppose that the diffuse diffraction patterns were caused by larger essentially homogeneous regions in which the arrangement of the molecules only approximates crystalline regularity. These regions which, except for occasional grosser irregularities, have a more or less uniform intermediate molecular order, may be identified with the fine electron microscopically visible fibrils. According to this viewpoint highly ordered micelles, unlike fibrils, are to be regarded more as incidental rather than as fundamental units of cellulose structure.
Polymerization of iodinated fibrinogen
Authors: Laki K. , Steiner R. 
Published: April 2003

AbstractLight scattering and ultracentrifuge experiments were made on iodinated fibrinogen. The molecular weight was found to be 560,000 and the length 900 A. The experiments on polymerized iodo‐fibrinogen indicated that the lateral and end‐to‐end associations have different pH optima.
Size and shape of the molecules in artificially branched polystyrene
Authors: Thurmond Carl D. , Zimm Bruno H. 
Published: April 2003

AbstractA sample of copolymer of divinylbenzene and styrene has been prepared and fractionated. Using the techniques of light scattering and viscometry the relations between the molecular size, intrinsic viscosity, and weight‐average molecular weight have been determined. The results may be interpreted in terms of the already existing theory of branched polymers. The curve of logarithm of intrinsic viscosity plotted against logarithm of molecular weight shows clearly the effect of branching in the polymer chains, the intrinsic viscosities of the higher molecular weight fractions being low compared to those of pure polystyrene. The mean square radius of the molecules as determined by light scattering shows similar effects, though complications obscure the picture. Some of the other solution properties of the branched materials also are peculiar. The results show that the semiquantitative determination of branching is possible in this way.
Vinyl‐type polymers containing phosphorus
Authors: Marvel C. S. , Wright John C. 
Published: April 2003

AbstractSome copolymers which contain either aldehyde or ketone carbonyl groups have been treated with phosphorus trichloride and then in sequence with acetic acid and water. On the basis of phosphorus analyses of the resulting products, α‐hydroxyphosphonic acid groups have been introduced in amounts ranging from zero to 100% of the theoretical amount. These phosphorus containing polymers with 2% or more of phosphorus are somewhat flame resistant.