bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on small‐angle interference maxima in synthetic organic polymers
Authors: Meibohm E. P. H. , Smith A. F. 
Published: April 2003

AbstractOff‐meridian small‐angle x‐ray interference maxima and multiple orders of small‐angle interference maxima have been observed for certain synthetic high polymer fibers including polythene, polyamides, polyethylene terephthalate, and polyvinyl alcohol. The observations indicate that the ordering of the structures responsible for small‐angle diffraction may be two‐ or three‐dimensional rather than one‐dimensional and that such ordering must extend over larger volumes of space than previously published data would indicate. The fibers must be given relaxation treatments to form the structures that result in small‐angle maxima except for polythene in which they appear merely on orientation. The relaxation treatments increase the crystallite size as shown by large‐angle pictures and modify the positions and shapes of the small‐angle maxima. An increase in the degree of relaxation increases the intensity of the interference and increases the magnitude of the interplanar spacing except for polyvinyl alcohol, in which the interplanar spacing is not affected. Samples of 66 nylon, which varied in molecular weight from 26,000 to 200,000 gave identical small‐angle interference patterns within the limits of accuracy.
A simple method of measuring the moment of disappearance of soap micelles during polymerization in emulsion
Authors: Klaassens K. H. , Bakker J. , Schoot C. J. , Goorissen J. 
Published: April 2003

AbstractIn this paper a simple method is described for determining the moment of disappearance of soap micelles during the emulsion polymerization of styrene by measuring the electrolytic conductivity during the polymerization.
Adhesion. IV. The meaning of tack temperature
Authors: McLaren A. D. , Li T. T. , Rager Robert , Mark H. 
Published: April 2003

AbstractHeretofore it has been assumed that, under the same experimental conditions of time and magnitude of applied pressure, all amorphous polymers have equal viscosities at their tack temperatures. Further evidence is obtained with a number of polymers in support of the theory. As a nonequilibrium property characterizing high polymers, tack temperature thus belongs in a category with brittle points, second‐order transition points, and softening temperatures.
The p‐phenylene linkage in linear high polymers: Some structure–property relationships
Authors: Edgar Owen B. , Hill Rowland 
Published: April 2003

AbstractThe high crystallite melting point of polyethylene terephthalate (Terylene) compared with the melting points of the aliphatic polyesters emphasizes the significance of the p‐phenylene linkage as an important factor determining polymer properties. A consideration of other polymer structures containing the p‐phenylene linkage shows that its influence is independent of any polar groups which may be present. X‐ray examination of the crystallite structure of polyethylene terephthalate and related substances has revealed no evidence of strong intermolecular forces.From a study of co‐polyesters based upon polyethylene terephthalate with aliphatic dibasic acids it is shown that the melting point of compositions containing more than 40 mole per cent of ethylene terephthalate is essentially independent of the aliphatic di‐basic acid employed. The Flory relationship between crystallite melting point and mole fraction of the units forming the crystallites shows fair agreement with the results obtained. The calculated latent heat of fusion of polyethylene terephthalate approaches closely to that of the corresponding aliphatic polyesters, and suggests that the high melting point induced by the p‐phenylene linkage is due to chain rigidity rather than to strong interchain attraction.This rigidity is consistent with the second order transition temperatures of such polyesters. It is shown that second order transition temperature is a linear function of the number of p‐phenylene linkages per unit chain length. The p‐phenylene linkage reduces the possibilities of change of shape available to a given length of chain, so accounting for the low entropy of crystallization and high melting point of polyethylene terephthalate.Evidence is advanced for the isomorphism of adipyl and terephthalyl linkages in linear polyamides. The absence of isomorphism in polyethylene adipate/terephthalate copolymers is ascribed to the weakness of the interchain forces.
Some types of organic high polymers and permutoids provided with active groups: Their synthesis, optical properties, and reactivity
Authors: Lautsch W. , Broser W. , Rothkegel W. , Biedermann W. , Doering U. , Zoschke H. 
Published: April 2003

AbstractThe synthesis and the properties of permutoids with ionic active groups and the kinetics of the decomposition of diazoacetic ester and of nitrosomethylurea through the ionic active groups are dealt with. A discussion follows of the synthesis of high polymers and permutoids with active groups of the chlorophyll and hemin series obtained by the introduction of the corresponding active groups into high‐polymeric compounds, by copolymerization, and by inclusion of the prosthetic group in the polycondensation process. A report is added on the optical properties of the high‐molecular compounds provided with active groups and on remarkable differences between low‐molecular compounds in a dissolved state and as active groups linked to high polymers. The apparatuses developed for taking absorption and reflection spectra are described. Finally, the catalytic effect of the high polymers provided with active groups of the hemin series is examined.
Copolymères greffés
Authors: Smets G. , Claesen M. 
Published: April 2003

AbstractDes copolymères greffés ont été préparés par réaction de transfert de chaǐne entre un radical monomérique et une molécule de polymère suivie de l'addition de monomère au macroradical. Dans ce but, les monomères vinyliques ont été polymérisés en présence de quantités appréciables (25% et plus) de polymère étranger, en présence de peroxyde de benzoyle comme initiateur (0.5% par rapport au monomère). La séparation des copolymères greffés des autres homopolymères présents dans le mélange est basée sur les différences de solubilité de ces produits. Les expériences ont été menées au départ d'acétate de vinyle en présence de polyméthacrylate de méthyle à différentes températures, savoir 75°, 85° et 95°C.; le taux de greffage dépend fortement de la t°, et atteint respectivement 15, 32 et 53% d'acétate de vinyle (analyses chimiques et infra‐rouges) Ces copolymères greffés ont été identifiés par leurs propriétés de solubilité et leur comportémént osmotique et viscosimétrique; les valeurs de k′ (constante de Huggins) et μ varient considérablement si on compare un mélange de polymères, un copolymère habituel et un copolymère greffé, dont les poids moléculaires et le taux d'acétate de vinyle sont semblables. De la měme façon, il a été possible d'obtenir un copolymère greffé par polymérisation du chlorure de vinyle en présence de polyméthacrylate de méthyle. Les réactions inverses toutefois, savoir la polymérisation du méthacrylate de méthyle en greffage sur les acétate ou chlorure de polyvinyle, n'ont pu ětre mises en évidence par des opérations de fractionnement. Des expériences semblables ont été effectuées à différentes températures avec le styrène en présence de polyméthacrylate de méthyle, et inversément le méthacrylate de méthyle en présence de polystyrène. Dans les deux cas les réactions réussissent et se manifestent par une solubilisation de la fraction polystyrénique. Dans le premier cas, la quantité de polystyrène solubilisé croǐt avec une augmentation de température. Ces copolymérisations par greffage sont reliées aux phénomènes de dégradation, décrites ailleurs, et à la stabilité des radicaux formés au cours des réactions.
Polyalkylene sulfides. X. The reaction of hexamethylenedithiol with 1,3‐butadiene1
Authors: Marvel C. S. , Cripps Harry N. 
Published: April 2003

AbstractHexamethylenedithiol and 1,3‐butadiene react in an emulsion system in the presence of peroxides to produce 1,6‐dicrotylmercaptohexane. Hexamethylenedithiol and 1,6‐dicrotylmercaptohexane did not yield a polymer by either bulk or emulsion techniques which confirms earlier work that a sulfur atom beta to a double bond prevents free radical initiated addition of a mercaptan to that bond. Hexamethylenedithiol does give a polymer with bicrotyl showing that a buried double bond will react. Polymerizations of hexamethylenedithiol with both biallyl ether and bis‐10‐hendecen‐1‐yl ether will take place, but they show that an oxygen atom beta to a double bond inhibits the free radical catalyzed addition of a mercaptan to that bond.
Copolymerization theory of the vulcanization of rubber. VI. Hydrogen sulfide effects and some self‐limiting features
Authors: Craig David , Juve A. E. , Davidson W. L. , Semon W. L. , Hay D. C. 
Published: April 2003

AbstractVulcanization with sulfur is ascribed to the formation of sulfur radicals which are believed to copolymerize with the rubber molecule double bonds. Hydrogen sulfide is proposed as necessary for chain initiation but when formed in sufficient amounts serves as a chain terminator. This is believed to lead to numerous self‐limiting features including ceiling temperatures, post‐vulcanization and delayed action effects. Initiation may result from the oxidation of H2S to sulfur radicals and termination to the formation of HS radicals.
Dynamic studies on polymeric liquids
Authors: Harper R. C. , Markovitz H. , Dewitt T. W. 
Published: April 2003

AbstractThe dynamic properties of low molecular weight polyisobutylene and silicone oils have been investigated over a range of frequencies and temperatures. When subjected to oscillating stresses, these materials behave as though they had a shear modulus as well as a viscosity. Dynamic viscosities and rigidities have been determined at frequencies between 10 and 100 cycles per second and at temperatures between −50° and +60°C. Falling ball viscosities were also obtained over the same temperature range. In general, moduli increase with increasing frequency and decreasing temperature while dynamic viscosities decrease with increasing frequency and increasing temperature. At room temperature and above, the dynamic viscosity varies very little with the frequency and is essentially the same as the falling ball viscosity. At lower temperatures the dynamic viscosity decreases considerably with increasing frequency but extrapolates to the falling ball viscosity at zero frequency. If these materials are regarded as complex Maxwell liquids, the dynamic rigidities and viscosities may be written as functions of a “reduced frequency” equal to the frequency multiplied by an exponential of a constant divided by the absolute temperature. This constant can be evaluated from the slope of the linear plot of the logarithm of the falling ball viscosity over the absolute temperature versus the reciprocal of the absolute temperature. For a given material a single constant suffices to bring the data at all frequencies and temperatures into a single plot similar to that used by Ferry.
Effect of solvation on sedimentation experiments
Authors: Wales M. , Williams J. W. 
Published: April 2003

AbstractThe sedimentation equilibrium of polymers in mixed solvents at infinite dilution of polymer was analyzed by thermodynamic methods equivalent to those used by Stockmayer and Kirkwood and Goldberg for the light scattering case. It was found that the apparent weight‐average molecular weight in a binary solvent mixture (when nonrefractometric methods are used to measure the experimental concentration gradient) is formally identical with that derived by Lansing and Kraemer on the assumption of stoichiometric combination of one of the solvents with the polymer. The “solvation number” now actually measures a preference for one solvent and can be expressed in terms of thermodynamic quantities characteristic of the ternary polymer‐solvent system. In the case of refractometric measurements, where the two solvents have different refractive indices, refraction terms similar to those encountered in light scattering theory for mixed solvents also enter. Under equilibrium conditions, for polymer solutions in pure solvents, thermodynamics can say nothing about “solvation,” which is inseparable from the over‐all nonideal behavior at finite concentrations. There is strong reason to believe that all types of experiments designed to measure solvation in mixed solvents under equilibrium conditions must give the same answer, since the same thermodynamic quantities determine polymer‐solvent interactions in all cases. By assuming a dynamic equilibrium between sedimentation and diffusion in the equilibrium case and using the sedimentation term for the sedimentation velocity case, an expression for the sedimentation constant in mixed solvents at infinite dilution of polymer has been obtained. This expression is almost the same as that previously derived by Schachman and Lauffer, the difference occurring in an assumption about the density of solvated liquid made by these authors.
Rates of initiation in vinyl polymerization
Authors: Baysal Bahattin , Tobolsky Arthur V. 
Published: April 2003

AbstractThe rates of initiation Ri of polymer chains in styrene and methyl methacrylate have been measured for four different catalysts. The results for styrene at 60°C are: Ri = 1.28 × 10−5[azo]; Ri = 2.96 × 10−6[Bz2O2]; Ri = 6.12 × 10−7[CHP]; Ri = 9.96 × 10−5[BHP]. Azo, Bz2O2, CHP, and BHP refer to 2‐azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, and tert‐butyl hydroperoxide, respectively. Rates are expressed in moles per liter per second. The corresponding results for methyl methacrylate at 60° are: Ri = 1.42 × 10−5[azo]; Ri = 6.62 × 10−6[Bz2O2]; Ri = 3.92 × 10−7[CHP]; Ri = 7.30 × 10−8[BHP]. Catalyst efficiencies for azo and Bz2O2 are shown to be nearly unity in both monomers. Chain transfer constants were calculated for all catalysts in both monomers. Photopolymerization was shown to proceed via chains growing in one direction only. The polymerizations were all carried out in the pure monomers (bulk polymerization) with exclusion of oxygen and other inhibitors.
Copolymerization characteristics of fumaronitrile
Authors: Price Charles C. , Gilbert Richard D. 
Published: April 2003

AbstractCopolymerization of fumaronitrile (M2) with styrene (M1) gave the following values for characteristic copolymerization constants: r1 = 0.23 ± 0.1; r2 = 0.01 ± 0.01; Q2 = 0.6; e2 = 1.6. With methyl methacrylate (M1) the values were r1 = 3.5 ± 0.5; r2 = 0.01 ± 0.01; Q2 = 0.4; e2 = 2.0.
Structure of neoprene. V. Viscosity‐conversion relationships in sulfur‐modified polychloroprenes
Authors: Mochel W. E. 
Published: April 2003

AbstractThe solution properties, i.e., gel content and intrinsic viscosity, of sulfur‐modified polychloroprenes were examined at monomer conversions ranging from 5 to 95% to obtain information about the mechanism of action of the sulfur modifier and other factors influencing the polymerization. Sulfur‐modified polymers isolated at conversions beyond 10–40%, depending upon the polymerization temperature, were found to be insoluble before treatment with tetraethylthiuram disulfide. These results, in confirmation of earlier results with radiosulfur, indicate that sulfur in chloroprene polymerization does not act as a chain transfer agent. The intrinsic viscosity‐conversion relationships for sulfur‐modified, tetraethylthiuram disulfide‐treated polychloroprenes show two viscosity maxima. The first maximum, at 15–20% conversion, appears to be the result of a change in polymer structure and, therefore, a change in the molecular weight‐intrinsic viscosity relationship. The second maximum appears at high conversion, 85–90%, and is caused by the formation of relatively tight gel that cannot be solubilized by the tetraethylthiuram disulfide scission reaction. The less pronounced decrease in viscosity beyond this peak is caused by removal of high molecular weight polymer by gelation, leaving relatively lower molecular weight sol polymer.
Effect of chemical structure on physical properties of isomeric polyesters
Authors: Izard E. F. 
Published: April 2003

AbstractIt has been shown that changes in chemical structure of aromatic polyesters have a pronounced effect on the melting points and crystallinity of the polymers. Changes which remove the carboxyl group from the ring result in marked lowering of the melting point and toughness of the polymers. Changes which separate aromatic nuclei lower melting point but not as markedly as the above change. Changes which put an odd number of atoms in the polymer chain markedly lower the melting point. Changes which interfere with the possibility of co‐planarity of the components very markedly affect the crystallinity, and to a lesser extent the sticking point of polymers.
Polyalkylene sulfides containing silicon. XI
Authors: Marvel C. S. , Cripps Harry N. 
Published: April 2003

AbstractThe optimum pH for the emulsion polymerization of hexamethylenedithiol and diallyldimethylsilane was found to be in the region of 3.0 to 4.0. A variety of polyalkylene sulfides containing silicon were prepared using bulk, solution, and emulsion polymerization techniques. All of the polyalkylene sulfides which contained silicon were heavy oily materials which were very “tacky”.
X‐ray diffraction studies of addition compounds of amylose with inorganic salts
Authors: Senti Frederic R. , Witnauer Lee P. 
Published: April 2003

AbstractMany salts in aqueous alcohol solution can be exchanged for the alkali in oriented filaments of alkali amylose. If the filaments are held taut during exchange, orientation is retained, and excellent fiber patterns are produced. By this method, compounds of amylose were obtained with the iodide, bromide, formate, acetate, and propionate of potassium and with sodium bromide and ammonium fluoride. In addition, potassium bicarbonate–amylose was formed by the action of carbon dioxide on moist filaments of potassium hydroxide–amylose. Data on the composition of the amylose–potassium salt filaments indicate stoichiometric compound formation between amylose and salt, the ratio of salt molecules to glucose residues being 1:2 for the iodide, bromide, formate, and tetragonal form of the acetate, and 1:1 for the propionate and the orthorhombic form of the acetate. As shown by x‐ray diffraction patterns, the potassium salts crystallized in two structures. One, based on a tetragonal unit cell, was common to the iodide, bromide, formate, acetate, and bicarbonate; the other, based on an orthorhombic unit, was the stable structure for the acetate and the propionate. Dimensions of the tetragonal unit cells of air‐dried filaments of the iodide and bromide were identical, with a0 = 10.7 and c0 (fiber axis) = 16.1 A. Corresponding dimensions for the formate and acetate were 10.8 and 16.1 A., and those for the bicarbonate were 10.8 and 15.8 A. The orthorhombic structures of the potassium acetate and propionate addition compounds with amylose appeared to be isomorphous, unit cells having a0 = 11.0, b0 = 18.1, c0 (fiber axis) = 17.9 A. for the acetate, and a0 = 11.4, b0 = 18.0, c0 = 17.6 A. for the propionate. The tetragonal structural modification is of particular interest. Observed diffraction maxima were consistent with the enantiomorphous space groups, P4121 and P4321, and this, together with composition and density data, demands that the amylose chains posses fourfold screw symmetry, with four glucose residues corresponding to the fiber repeat period of 16.1 A. Succesive residues in the amylose chain must, therefore, be identical. This is the first x‐ray evidence which has demonstrated the identity of successive residues in the amylose chain.From a Patterson projection of potassium bromide amylose, the positions of the inorganic ions were determined. The Fourier projection, ρz(x,y), computed from Fhk0 with signs determined by the bromide ion, confirmed the location of the inorganic ions and gave a general outline of the packing of the amylose chains.
Polysoaps. III. Influence of solubilized benzene on reduced viscosity of an n‐dodecyl bromide addition compound of poly‐2‐vinylpyridine
Authors: Layton Lionel H. , Jackson Earl G. , Strauss Ulrich P. 
Published: April 2003

AbstractThe effect of solubilized benzene on the viscosity of aqueous solutions of a polysoap, derived from poly‐2‐vinylpyridine and n‐dodecyl bromide was found to be different, both in kind and in order of magnitude, from the simple viscosity depression characteristic of solubilized aliphatic hydrocarbons. As the benzene content of a given solution is increased, the viscosity at first rises, reaches a maximum, and decreases again, below its initial value, until the solution is saturated. The maximum rise in the reduced viscosity increases very strongly with increasing concentration of the polysoap, indicating that the viscosity increase is caused by interactions between polysoap molecules. On the other hand, the reduced viscosity depression at benzene saturation is not sensitive to the polysoap concentration and may therefore be ascribed to a contraction of the individual polysoap molecules. Both at the viscosity maximum and at benzene saturation, the respective amounts of benzene solubilized by unit amount of polysoap were found to be independent of the polysoap concentration. These results are interpreted to mean that the polysoap molecules act as independent solubilizing units, but that their structure is changed by the solubilized benzene is such a way as to strongly affect their mutual interaction. Based on the assumption that the benzene is solubilized both in the hydrocarbon and in the ionic regions of the polysoap molecules, a mechanism for the structure changes which would explain the viscosity maxima is suggested.
Molecular weight dependence of intrinsic viscosity of polymer solutions
Authors: Krigbaum W. R. , Mandelkern L. , Flory P. J. 
Published: April 2003

AbstractIntrinsic viscosities of low molecular weight polystyrene fractions measured in an “ideal” solvent (i.e., in cyclohexane at the “θ temperature,” 34°C.) are in accord with the relationship [η]θ = KM1/2. Even at a molecular weight of only 4000, the observed value of K agrees with that for high molecular weights.
Activity coefficient of byions and ionic strength of polyelectrolyte solutions
Authors: Kagawa Ikumi , Katsuura Kakuji 
Published: April 2003

AbstractWith the polyelectrolyte solutions prepared by adding potassium chloride into the solution of sodium carboxymethyl celluloses in the various proportions, the activity of chloride ion was measured potentiometrically, from which the ionic strength of the sample solutions was computed. From these experimental results it has been found that Lewis' law of ionic strength, although it does not hold in the original sense as it is, seems applicable for the polyelectrolyte solutions if an assumption is permitted that the so‐called segment accompanied by a portion of counterions behaves like a permanent point‐charge ion. Thus, the degree of fixation of counterions was computed, and the dissociation state of strong polyelectrolyte was discussed. Furthermore, a brief report was made on the difference between the activity coefficients of byions and counterions in their thermodynamical meaning as well as on the connection of the nature of polyelectrolyte solutions with that of simple electrolyte solutions according to the authors' two phase conception.