bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress birefringence and optical anisotropy of macromolecules in swollen polymers
Authors: Tsvetkov V. N. , Grishchenko A. E.
Published: September 2014

Stress birefringence of several polymers swollen in various solvents was experimentally investigated. Gels of polystyrene (PS), natural rubber (NR), polydimethylsiloxane (PDMS), cyanoethylacetylcellulose (CEAC), and cyanoethyltritylcellulose (CETC) were studied over a wide range of degrees of swelling from dilute solutions to concentrated gels. In all systems where the increment of polymer–solvent index of refraction dn/dc differs from zero the form effect in stress birefringence is observed to be proportional to (dn/dc)2 in accordance with the theory. The dependence of stress birefringence on the concentration of a polymer allows us to determine the relative roles of macro‐ and microform anisotropy in the total stress birefringence. For rigid chains of cellulose esters at all concentrations form birefringence appears to be a microform effect. For flexible chain molecules of synthetic polymers, the microform effect plays the principal part at high concentrations. According to theoretical predictions the magnitude of the microform effect for cellulose derivatives is many times greater than for flexible polymers. In both cases the form effect is caused neither by micelles nor by macroheterogeneities in gels, but is molecular in nature. Its magnitude depends on the segmental mass of the molecular chain. The use of the microform effect theory with experimental data obtained on stress birefringence of gels permits the determination of the masses of molecular segments Ms for all the polymers investigated. Values Ms thus obtained agree with segmental dimensions determined by viscometry and light‐scattering methods.
Crystal structure of isotactic poly (vinyl methyl ether)
Authors: Corradini P. , Bassi I. W.
Published: September 2014

The crystal structure of isotactic poly(vinyl methyl ether) has been defined on the basis of x‐ray fiber spectra. Isotactic poly(vinyl methyl ether) crystallizes in a rhombohedral unit cell whose constants referred to hexagonal axes are: a = b = 16.25 ± 0.15 A., c = 6.50 ± 0.05 A. (chain axis) Z = 18, dcalc. = 1.168 g./cm.3. Probable space group \documentclass{article}\pagestyle{empty}\begin{document}$ \[R\overline 3 \] $\end{document}. The

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monomeric units repeat along a threefold helix. Atomic positions were deduced by trial and error. Right‐handed and left‐handed macromolecules are contained in the unit cell and each macromolecule is surrounded by three enantiomorphous, anticlined macromolecules. The internal rotation angles around the CC bonds, defined with respect to the main chain bonds, have been found to be 280° and 160° for the right‐handed helix (the macromolecule is growing anticlockwise) and 80° and 200° for the enantiomorphous macromolecule. A comparison between the packing of the macromolecules of isotactic poly(vinyl methyl ether), of isotactic poly‐α‐butene (modification 1), and of other isotactic polymers is carried out.
Investigation of the ∈‐caprolactam polymerization process in the presence of hydrazine derivatives
Authors: Grekov A. P. , Yanchevsky V. A. , Kornev K. A. , Sukhorukova S. A.
Published: September 2014

The caprolactam polymerization process in the presence of the hydrazine derivatives has been investigated. During polymerization of ∈‐caprolactam in the presence of these initiators an induction period was observed in all cases due to formation of the product of the interaction of caprolactam with the initiator. The induction period and the molecular weight were ascertained to decrease with increase in the initiator's content. The initiator penetrates into macromolecular chain and thus regulates its molecular weight. The reaction rate was shown to be proportional to the square root of the initiator concentration. The given process obeys the kinetic regularities of a reversible first order reaction with respect to the monomer concentration and it agrees with the Arrhenius equation. On the basis of this investigation the scheme of the process was suggested and the constants of the initiation and the chain growth rate were calculated.
Study of crosslink formation by partial conversion properties. III. Copolymerization of styrene with polyethylene fumarates
Authors: Burnett G. M. , Pearson J. M. , Smith J. D. B.
Published: September 2014

The copolymerization of polyethylene fumarate and styrene has been investigated in dilute solution in dioxan at 60°C. by using partial conversion molecular weight to follow the reaction. Reactivity ratios have been measured, and the effects of reactant concentration on these ratios are discussed. The results are interpreted in terms of the relative contributions of inter‐ and intramolecular crosslinking reactions to the system.
Influence de la Morphologie a L'état Solide des Constituants des Copolymères Greffés sur leur Comportement Physicomecanique. Système Polyacrylate d'éthyle et Copolymère Styrolène–Anhydride Maléique
Authors: Agostini M. , Lebel P.
Published: September 2014

Similarly to most graft polymers, the system examined in this study presents in the solid state two phases, each of which can be spread out or entangled. If the spreaded compound is present in sufficient proportion, it forms the continuous phase and its nature determines the macroscopic properties of the graft copolymer. The graft copolymers were prepared using the preozonizations technique with backbone and graft being alternatively ethyl polyacrylate (PAE) and a styrene‐maleic anhydride copolymer (PSAM). The phases separation is taken in evidence with the electron microscope. The influence of the nature of the continuous phase on the chemical properties is shown by dynamometric measurements. The differential thermal analysis shows that there is no ship of the glass transition temperatures (Tg) with respect to those of both homopolymers, but that the entropy changes at the transition are function of the spreading out of the polymer chains. Dielectric relaxation measurements show an absorption identical to that of the α relaxation of PAE. In a graft copolymer where PSAM is the continuous phase and therefore appears to be rigid, the entangled chains of PAE of the discontinuous phase possess a higher mobility than when they form the continuous phase.
Crystallization kinetics of polycarbonates. I
Authors: Turska Eligia , Przygocki WĐAdysđaw , Masđowski Marian
Published: September 2014

Research on the kinetics of crystallization of polycarbonates based on bisphenol A at 190°C. has been carried out on six polydisperse samples. It was found that the process of crystallization, after a long period of induction, follows a course which can be described by the classical equation of Avrami. The final amounts of crystallization are small, ranging from 18 to 28%. Crystallization kinetics of polycarbonates depends on molecular weight and on the previous treatment of the polymer.
Role of free volume changes in polymer solution thermodynamics
Authors: Patterson D.
Published: September 2014

The thermodynamic effect of free volume changes in mixing is treated with the use of the corresponding states theory of Prigogine and collaborators. The interaction parameters χ1, κ1, ψ1 and their concentration dependences are derived. Each parameter contains two terms. The first is due to differences in cohesive energy and sizes between segments of polymer and solvent: the second or “structural” contribution is due principally to the difference in chain lengths between polymer and solvent. The structural effect gives a large value of χ1 ∼ 0.4 for a polymer with a chemically identical short oligomer as solvent. A minimum but nonzero value of χ1 occurs for a solvent with higher cohesive energy than between polymer segments. At high temperatures a lower critical solution temperature must occur due to the increase of the solvent configurational heat capacity to infinity as the solvent vapor‐liquid critical point is approached, the heat and entropy of dilution becoming negative. At ordinary temperatures χ and κ increase with polymer concentration. The solubility parameter approach is compared; particular polymer liquid models used by Prigogine and by Flory are briefly discussed. χ1 as calculated for natural rubber and a variety of solvents and fair agreement is obtained with published values.
Morphology of solution‐crystallized polypropylene
Authors: Morrow D. R. , Sauer J. A. , Woodward A. E.
Published: September 2014

Results are presented of the structures obtained upon crystallization of polypropylene from dilute solutions in α‐chloronaphthalene. It is shown that under proper conditions of concentration and crystallization, isotactic polypropylene can be caused to grow in the form of lath‐shaped single‐crystal lamellae. Electron diffraction pictures of these lamellae indicate a monoclinic crystal structure. Crystals have been grown both from whole polymer and from sharp molecular weight fractions. When crystallization from dilute solutions (0.4–0.001 wt.‐%) is allowed to take place under ambient cooling conditions, the crystals formed are not well defined, but tend to be more ordered if fractions are used. When fractions are crystallized under constant temperature conditions (from 90 to 115°C.) the resulting structure formed tends to be a close‐packed interwoven array of individual elements. However, if whole polymer is used the aggregate has a more open weave structure and, upon deposition upon a carbon substrate, the elements making up the quadrites tend to collapse at the edges. Electron transmission and diffraction pictures show these elements to be single lamellar crystals of polypropylene with well‐defined edges and with thicknesses of the order of 125–150 A. Fracture of crystals by ultrasonic vibration leads to the presence of fibrils between the separated parts when the break is at right angles to the a direction, but to no fibrils when the break is parallel to this direction. These results suggest that the polypropylene chains are folded, and that the fold planes are parallel to the a crystallographic axis
The radiation‐induced polymerization of dienes with sulfur dioxide
Authors: Kearney J. J. , Stannett V. , Clark H. G.
Published: September 2014

Copolymers of sulfur dioxide and butadiene, isoprene, 2,3‐dimethylbutadiene, and chloroprene were prepared by irradiation at low temperatures with remarkably high efficiency. The polymers were all insoluble in the monomer mixtures and therefore only limited kinetic data could be obtained. However, the following conclusions could be reached from the data. Isoprene, butadiene, and 2,3‐dimethylbutadiene all produced 1:1 copolymers with sulfur dioxide across a wide range of temperature and composition. At high sulfur dioxide contents the cyclic sulfones began to form. Chloroprene behaved differently in that copolymers containing considerably more than 50 mole‐% of chloroprene were obtained. Also, the infrared spectra revealed a considerable proportion of pendant vinyl groups as compared with the predominately 1,4 addition in the case of the other dienes studied. The isoprene and 2,3‐dimethylbutadiene polymers were found to be soluble in highly polar solvents containing dissolved salts. At lower temperatures the radiation caused concurrent degradation of the polymer. The compositions of isoprene, 2,3‐dimethylbutadiene and sulfur dioxide terpolymers were found to be unusually sensitive to the polymerization temperature. Thermal gravimetric analysis of the various polymers showed thermal stabilities in the order, 2,3‐dimethylbutadiene > isoprene and butadiene > chloroprene. A sample of tetramethylene polysulfone prepared chemically showed greatly enhanced thermal stability, catastrophic degradation beginning about 100°C. higher than the corresponding butadiene copolymer. Attempts to hydrogenate the diene copolymers were unsuccessful although the corresponding cyclic sulfones were hydrogenated successfully. The highly efficient radiation polymerizations are believed to be free radical in nature and to proceed via monomer complex function. The difficulty of chain termination between sulfonyl radicals is suggested as a reason for the very high yields and molecular weights obtained at low temperatures.
Model structures for vinyl polymers. III. Equilibrium tacticity of 2,4‐dimethylglutaric acid and 2,4,6‐tricarboxyheptane
Authors: Clark H. G.
Published: September 2014

Model compounds of the general formula H(CH2CHX)nCH3 (where n = 2 and 3 and X = CO2H, CO2CH3, CO2C2H5, CO2CH(CH3)2 and CN) have been prepared. These compounds were brought to steric equilibrium by treatment with alkaline catalysts and the equilibrium concentrations measured by gas chromatography. The syndiotactic configuration is preferred over the isotactic in all cases. Steric factors are more important than polarity for the systems which were investigated. It is proposed that the equilibrium triad content of the high polymers is approximated by the equilibrium composition models where n = 3.
Kinetics of radical polymerization. XX. Energy transfer processes in liquid‐phase radical reactions
Authors: Tüdös Ferenc
Published: September 2014

In order to account for the significant stoichiometric anomalies observed in the course of investigations on inhibited radical polymerization, the author propounded the hot‐radical hypothesis, according to which the reaction heat released during the formation of the active centers can serve as a source of activation energy in the subsequent reactions. This hypothesis is based on the assumption that the relaxation (the vibrational deactivation of the hot radicals) is essentially a slow process. To control this assumption in a direct way, the author conducted experiments in which vibrationally excited radicals were produced by UV irradiation of the initiators. The primary hot radicals formed were added onto various unsaturated compounds and thus transformed into more stable radicals, the concentrations of which could be measured with the aid of the ESR method. A comparison of the steady concentrations of the intermediate radicals formed under the effects of thermal and hot radicals, respectively, permits the rate and the probability of the relaxation of the hot radicals to be determined.
The viscoelastic relaxation mechanism of inorganic polymers. III. The sodium polyphosphates
Authors: Eisenberg A. , Sasada T.
Published: September 2014

The sodium polyphosphates represent a class of materials in which the viscoelastic relaxation mechanism in the glass transition region (≈300°C.) could be either molecular flow or bond interchange. At room temperature in aqueous solution these polymers behave like the normal organic polymers in which only molecular flow is encountered, whereas in the melt at 65°C., bond interchange is known to occur. To elucidate which of these two mechanisms is responsible for the relaxation behavior of the polyphosphates, two studies were undertaken. In the first, the viscoelastic properties were investigated as a function of the chain length and of the nature of the terminal units. The results indicated that molecular flow was the mechanism responsible for the relaxation behavior. In the second study, radioactive low polymer was mixed with inactive high polymer, and the mixture separated chromatographically after heating. No evidence of interchange was found here either, confirming the result of the first study.
Dipole moments of stereoregular polymethyl methacrylate in solution
Authors: Roig A. , Horta A.
Published: September 2014

Three samples of stereoregular PMMA were studied by calculating their dipole moment from the experimental data of dielectric constant, specific volume, and refractive index measured on PMMA solutions in toluene at several temperatures in the interval 20–90°C. The tacticity of the samples is investigated by NMR. Results show that the highest dipole moment corresponds to isotactic polymer. However, no exact relation between tacticity and μ can be found. It would be necessary to have further knowledge of the distribution of regular sequences in the chain and of its length, rather than the quantity of individual units given by NMR. Dependence with temperature shows a smooth variation.
Zur Theorie der Phasentrennung im Ternären System Polymer–Lösungsmittel—Fällungsmittel
Authors: Klein J. , Patat F.
Published: September 2014

The basis of the theoretical discussions of this paper is a number of experiments concerning (a) the composition of the coexisting phases formed during precipitation fractionation, (b) the dependence of the initial point of phase separation on polymer concentration and molecular weight distribution, and (c) the amount of precipitated polymer. A discussion of the thermodynamic equations shows that the divariant distribution–equilibrium as following from the assumption of a Nernst equilibrium of polymer distribution between two immiscible liquid phases can be excluded. The experimentally determined constancy of the phase composition—independent of the initial concentration of the solution—confirms the univariant behavior of the system as following from the statistical thermodynamic theory. Therefore the precipitation process has to be described as a separation process from homogenious phase by phase formation. Contrary to commonly accepted theoretical results however, the behavior of a polydisperse system is determined by the partial concentrations of the various degrees of polymerization forming the mixture. Discussing the molecular‐kinetic steps of the precipitation process, one can say that in the solution the polymer chain forms polymer–solvate molecules of definite composition. The nucleation process—naturally preceding the phase separation—can be understood as an association process by forming intermolecular polymer–polymer contacts between the solvate molecules. A molecular weight specific ability of association may explain the dependence of precipitation on the partial concentration of polymer. The question whether the structure of the gel phase has to be interpreted as polymer–solvate complex or as a kind of swollen network cannot be answered yet.
The limit phenomenon in copolymerization of tetrahydrofuran with propylene oxide
Authors: Korovina G. V. , Novikovs D. D. , Barzikina R. A. , Kuzaev A. Y. , Entelis S. G.
Published: September 2014

In this work the occurrence of the limit in the copolymerization of THF and PO in bulk on tetrahydrofuranate trifluoride borane was studied within a temperature range from −10 to 20°C. and BF3 concentrations from 0.05 to 0.5 mole‐%. Under all conditions studied the copolymer yield was no more than 80%, the yield decreasing with THF concentration in the initial mixture. Increase in the catalyst concentration, other conditions being equal, promotes the reaction to higher yields. The addition of either of the two comonomers in the terminated reaction zone does not change the limit value. The addition of 20 wt.‐% of epichlorhydrin relative to the initial THF–PO mixture in the terminated reaction zone promotes complete polymerization.
The mechanism of the formation and the constitution of flavonoid tannins
Authors: Weinges Klaus
Published: September 2014

The majority of the flavonoid tannins that occur in tanning woods very probably originate by acid‐catalyzed intermolecular condensation of hydroxyflavan‐3‐ols (“catechins”) and hydroxyflavan‐3,4‐diols (so‐called “leucoanthocyanidins”) without the participation of enzymes. The mechanism of the reaction and the stereoselectivity of the acid‐catalyzed intermolecular condensation of catechins are described. The mechanism for the formation of flavonoid tannins consists of a primary polymerization step and a secondary condensation with elimination of water. These two steps are illustrated by the condensation of the dicatechin IV and that of the anhydrodicatechin VII, VIII, or IX. It cannot yet be decided whether the dehydration step occurs after the addition of each new molecule of catechin to the growing tannin. For this reason, the constitution of the flavonoid tannins is best represented by a combination of the formulas VI and X.
Some regularities of butadiene polymerization initiated by the “cobalt” catalyst and role of π‐allylic systems in stereospecificity
Authors: Dolgoplosk B. A. , Tinyakova E. I. , Vinogradov P. A. , Parenago O. P. , Turov B. S.
Published: September 2014

Nucleophilic additives and potassium and sodium chlorides, complexing with alkyl aluminum chlorides, are shown to result in an increase in the 1,2 structure of polybutadiene and a sharp decrease in molecular weight and polymerization rate. Trialkyl aluminum behaves in a similar way. There exists a correlation between these effects and the reducing power of the system. A mechanism of the influence of various compounds on the polymerization process is proposed. A mechanism of the formation of 1,4 and 1,2 polymer units is discussed with respect to the role of π‐allylic systems in diene polymerization and the nonequivalence of carbon atoms bonded to metal atoms in π‐crotylic systems.
Determination of the isotacticity of polypropylene by infrared spectroscopy
Authors: Kotschkina A. , Grell M.
Published: September 2014

A method for determining isotacticity of polypropylene is proposed, which is based on the measurement of the ratio of the optical density of the 1000 (isotactic) and 1460 cm.−1 (“internal” standard) bands (D1000:D1460). The method has been compared with the extraction method and the other infrared methods. It has been shown that the other infrared methods are unreliable, either because of the failure of the 975 cm.−1 band to behave as a true “internal” thickness band, or because of the wrong assignment of the isotactic band.
Fraktionierung von Polyacetalen
Authors: Grohn H. , Friedrich H.
Published: September 2014

Two apparatus are described which allow fractionation of polyacetales showing different molecular weight distributions with sufficient reproducibility. Results obtained by the discontinuous and continuous elution method are compared to those obtained by a modified solution fractionation method, originally devised by O. Fuchs. Within experimental error the three methods give the same mass distribution curve. An equation is proposed by means of which it is possible to calculate the variation of the concentration in the mixing vessel during a fractionation with the eluted volume. By changing certain parameters of the equation the variation of the concentration may be fitted to any molecular weight distribution.
Homogene Polymerization des Acrylnitrils in Anorganischen und Organischen Lösungsmitteln
Authors: Ulbricht Joachim
Published: September 2014

The homogeneous polymerization of acrylonitrile in anorganic (Mg(ClO4)2) aqueous salt solutions proceeds with greater rates and results in higher degrees of polymerization than in organic solvents. The rate dependence of the degree of polymerization has been determined. Calculation of the degree of polymerization has been performed, taking into consideration the termination by disproportionation and recombination, as well as the change in molecular weight distribution, provoked by transfer reactions. The ratio of the rate constants kt/kp2 is shown to decrease by a factor of 102 in organic salt solutions compared with that in dimethylformamide and dimethylacetamide, whereas the rate of initiation is only little changed in all the solvents investigated. Furthermore, the mean lifetimes of radicals have been determined by intermittent illumination and is shown to be lower in dimethylformamide than in dimethylsulfoxide, ethylene carbonate, and aqueous magnesium perchlorate solution, provided that the polymerization rate is the same. From that it follows that the propagation rate of acrylonitrile is equal in the organic solvents investigated, but increases by a factor of 107 in the salt solutions.
Highly unsaturated polymers of polyethynylpolyarene and polyazopolyarene series
Authors: Kotlyarevskii I. L. , Shvartsberg M. S. , Fisher L. B. , Zanina A. S. , Bardamova M. I. , Terpugova M. P.
Published: September 2014

Two new classes of highly unsaturated polymers—polyethynylpolyarenes and polyazopolyarenes are synthesized by oxidative polycondensation of polyethynylarenes in the first case and of aromatic diamines in the second one and investigated. The polymers have common formulas H[(CC)kAr(CC)k]nH and H2NArN(NArN)NArNH2 respectively. The polymers either keep the conjugation along the main chain or the conjugation is intentionally broken. This is attained by changing the structure of the arylenic part of the monomers. Depending on the structure, electrical properties of the polymers vary in a wide range. For example the conductivity at 20°C. varies from 10−2 to 10−20 ω−1 cm.−1. The temperature dependence of conductivity is σ = σ0 exp {−E/kT}. The activation energy is specially predetermined by the structure and can vary in the range of 0.1 to 4.7 e.v. Similarly magnetic, dielectric, catalytic and other properties and solubility can be changed by varying the structure.
Vibrational and NMR spectra and molecular structure of poly(vinyl chloride)
Authors: Schneider B. , Štokr J. , Doskočilová D. , Kolínský M. , Sýkora S. , Lím D.
Published: September 2014

Infrared spectra of PVC in the region of CCl stretching vibrations and the β proton band in NMR spectra of PVC are interpreted, based on the analysis of infrared and NMR spectra of pure stereoisomers of 2,4‐dichloropentane and 2,4,6‐trichloroheptane. For the interpretation of infrared spectra, only the presence of conformations found to be stable in model compounds has been assumed. The combined evidence of NMR and infrared investigations indicates that interpretations can be found to describe PVC samples prepared by radical polymerization at +50°C. as atactic, and those prepared at −25°C. as about 60% syndiotactic.
Electronic properties of poly(azothiophenylenes), polymers with systems of conjugated bonds in the backbone chain
Authors: Poniński M. , Kryszewski M.
Published: September 2014

In the course of investigations of electron spectra of previously obtained four fractions of poly(azothiophenylenes) PATPh it was stated, that benzene rings form quinoic structures, and NN or NN groups and S atoms exist in the chain. On the basis of EPR studies the numbers 1016–1018 and 1019 spins/1 g. are obtained for different fractions and for that pyrolized at 625°C., respectively. The investigations concerning electric conductivity and thermal activation energy show that these polymers exhibit a rather poor conductivity. A tentative interpretation of the conductivity is suggested on the basis of discussion of different models of electron mechanism.
Radiolyse Oxydante du Polyoxyéthylèneglycol en Solution Chloroformique Diluée
Authors: Gugumus François , Marchal Jean
Published: September 2014

The radiation chemistry of polyethylene oxide in aerated chloroform solutions was studied by exposure to cobalt 60 gamma rays. The rate of chain scissions was determined by viscosity measurements. The rates of formation of formates and formals resulting from degradation were measured by IR spectroscopy and colorimetry. To interpret the results we propose a kinetical scheme based on monomolecular decomposition of peroxy macroradicals PO2 leading to a formate and an α‐alcoxyalcoxyl radical. As this radical can attack other polymer molecules or its own chain, the degradation is explained by means of the superposition of a random scission process and of a nonrandom one leading to products of low molecular weight.
Étude par Birefringence d'Écoulement et Viscosimétrie de Copolymères Greffés
Authors: Gramain Philippe , Leray Joseph , Benoit Henri
Published: September 2014

Two series of graft copolymers, polymethylmethacrylate—polystyrene (PMM–PS) and polydiphenylpropene—polystyrene (PDP–PS), have been investigated by streaming double refraction and by viscosimetry. The results obtained in bromoform, which cancels the form effect, show that the intrinsic anisotropy is positive for the PMM–PD type and negative for the PDP–PS type. Consequently, these two families of compounds have a different morphology in solution. The influence of the various structural factors, such as the number and length of the grafts, and the mass of the backbone, on the anisotropy of the macromolecule has been considered. For the PDP–PS type, we suggest a model with properties similar to those of a statistical coil and for the PMM–PS type, a model composed of a core of PMM surrounded by the PS.
Comparaison des Propriétés de Solutions de Poly‐2‐Vinylpyridines Atactiques et Isotactiques
Authors: Loucheux Claude , Czlonkowska Zofia
Published: September 2014

We have prepared an atactic polymer of 2‐vinylpyridine by bulk polymerization at 30°C. with azobisisobutyronitrile as the initiator. The fractionation furnishes seven fractions. In addition, we have obtained a series of isotactic poly‐2‐vinylpyridines by homogeneous phase polymerization with phenylmagnesium bromide as initiator. We have studied these polymers by viscosity and light scattering techniques. In solution in absolute ethanol and in dimethylformamide, the behavior of atactic polymers is quite usual and we have established the two relations:

On the other hand, in the same solvents, the isotactic polymers present an important polyelectrolyte effect. This effect disappears by adding soluble electrolytes in the solvents, and in these conditions it is possible to give the two relations:

For the atactic polymers, we have the relation:

We think that a small extent of quaternization of isotactic polymers is responsible for the effects observed.
Polymérisations Provoquées par le Calcium Metal
Authors: Parrod Jacques , Sinn Victor , François Bernard , Mayer Nicole
Published: September 2014

Isoprene has been polymerized with calcium converted into powder. Three methods have been investigated to reduce the metal: evaporation of the ammoniacal solution, distillation in argon atmosphere, and grinding. The structure of the polymers has been studied.
Combinaisons Cristallisées des Polyoxyéthylènes et des Polyesters avec l'Urée et la Thiourée
Authors: Parrod Jacques , Kohler André , Hild Géradd , Mayer Roger
Published: September 2014

Urea gives adducts with polyoxyethylenes, with polystyrene—polyoxyethylene block polymers, and with some polyesters. Three ways can be used to get them: one can shake powdered urea with the polymer solution, or grind the solid constituents, or mix them in homogeneous solution. The first procedure is described with some details. The main properties of these addition compounds, and their crystalline structure are reviewed.
Étude par Ultracentrifugation Analytique d'un Système Enzymatique Monomère—Polymère (Polyphénoloxydase)
Authors: Arnaud Y.
Published: September 2014

Polyphénoloxydase (P.P.O.) is an enzyme responsible for the hydroxylation of monophenols to the ortho forms, and also the oxidation of these o‐diphenols to o‐quinones. It is a macromolecule biologically active in the form of a tetramer. In order to study “monomer—oligomer” transformations, we made use of an analytical ultracentrifugation method which enables the hydrodynamic constants and the weight of the macromolecule to be determined on preparations diluted to the physiological concentration level (μg./ml.)8 This method consists in following the P.P.O. sedimentation during ultracentrifugation, observing the transformation of diphenol into o‐quinone by ultraviolet absorption. Physical properties of an enzyme in the course of its action on the substrate are thus determined. This method insures the functional integrity of the molecule, and provides the best criterion of specificity. This study has enabled us to show various degrees of polymerization of this macromolecule, and to follow the influence of changes in its quaternary structure on its functional activity.
Monodisperse stereoregular poly(methyl methacrylate) by anionic polymerization. II
Authors: Roig A. , Figueruelo J. E. , Llano E.
Published: September 2014

Anionic polymerization of poly(methyl methacrylate) in solvating media (THF, glyme, pyridine), using as initiators complexes of the type organic—alkali metal(biphenyl—sodium, biphenyl—lithium), is described, leading to stereoregular and monodisperse polymers. Polymerization is carried out in a vacuum line system, all solvents being previously purified with the same type of complexes used in the polymerization reaction; monomer is purified with benzil—sodium. All transfers are made through sealed ampules. The polymers obtained were fractionated and found to have very narrow molecular weight distributions. All polymers are mainly syndiotactic and their NMR spectra allow the steric composition to be determined, which goes up to 97% syndiotactic. The polymerization can be described by a single parameter governing the probabilities of isotactic and syndiotactic placements, as predicted by the Coleman and Fox theory.
Some solution properties of polyoxymethylenes
Authors: Grassie N. , Roche R. S.
Published: September 2014

Perfluoroacetone hydrate (PFAH) is a useful nondegrading solvent for high molecular weight polyoxymethylenes (POM) at ordinary temperatures. Infrared spectroscopic measurements on mixtures of low molecular weight POM diisopropyl ethers and PFAH in carbon tetrachloride solution give evidence of specific polymer—solvent interactions involving hydrogen bonds. Although the viscosity behavior of POM in PFAH and PFAH—H2O mixtures conforms to the Huggins equation, the values of the Huggins constant are not consistent with the values expected on theoretical grounds. Much more satisfactory values are obtained by application of the Schulz—Blaschke viscosity relationship.
On the mechanism of thermo‐oxidative degradation of cellulose ethers
Authors: Kozmina O. P.
Published: September 2014

Cellulose and alcohol ethers of aliphatic series, benzyl, allyl cellulose and other ethers containing labile hydrogen atoms were shown to undergo thermo‐oxidative degradation owing to the formation of peroxide in the ether groups and to their decomposition with the removal of the corresponding aldehydes, alcohols, alkylhydroperoxides, and other products and the break of the pyranose cycle. This has been established by the method of labeled atoms. It was also shown that the peroxide groups in ethers are partially transformed into the corresponding ester groups. The reaction of ethyl cellulose with oxygen was investigated in greater detail. Kinetic data on the formation of ether peroxides and of the products of their decomposition are given. Cellulose ethers and esters in whose ether and ester groups the labile hydrogen atoms are absent (tritylcellulose, pivalinates, benzoates, etc.) are much more resistant to thermo‐oxidative degradation.
Methode d'Etude Cinétique des Réactions de Polymérisation Anionique
Authors: Guyot Alain , Vialle Jean , Le Doan T. , Tho Pham Quang
Published: September 2014

Beside the usual reactants, the reaction medium of polymerization contains two inert compounds IM and IC, which act as internal standards of concentration corresponding, respectively, to the monomer M and the organometallic catalyst RMe. At given time intervals, small liquid samples are picked up and injected into a vaporization cell together with small amounts of water or alcohol. Then a part of the gaseous mixture is analyzed by gas chromatography. The consumption of the monomer and of the catalyst are obtained from the measurements of the ratios of the areas under the peaks M and IM, and RH and IC. Some results are given for the polymerizations of vinyl chloride with an organomagnesium catalyst and of isoprene with n‐butyllithium.
Synthesis of new ferrocene‐containing polymers
Authors: Paushkin Ya. M. , Vishnyakova T. P. , Machus F. F. , Sokolinskaya F. A. , Golubeva I. A.
Published: September 2014

Six new polymers based on ferrocene and its derivatives have been synthesized and their electrophysical properties investigated. The polymers were prepared by various methods. In polymerization of acetylferrocene oxime and difulvene of 1,1′‐diacetyl‐ferrocene the yield of polymers was 90%. In the direct interaction of ferrocene and hexamethylene diisocyanate, poly(ferrocenylene polyamide) resulted in 73% yield. The polycondensation of ferrocene both with phthalic anhydride and with carbamyl chloride, and that of acetylferrocene with ammonium bicarbonate, in the presence of zinc chloride gave new ferrocenic polymers with a system of conjugated bonds. All produced polymers were coloured powders partly soluble in organic solvents. In the direct interaction of ferrocene and carbamyl chloride (in the form of a complex with zinc chloride) (poly‐(ferrocenyl nitrile), not described previously, has been obtained. By polycondensation of acetylferrocene and ammonium bicarbonate the insoluble polymers and oligomer of molecular weight 480 and m.p. 145‐150°C. containing two hydroxy groups have been prepared. The presence of CN bonds in poly(ferrocenyl nitrile) and the products of polycondensation of acetyl‐ and 1,1,‐diacetylferrocene with ammonium bicarbonate has been confirmed by the complexing effect of CN bonds with a silver salt. Silver extraction due to the complex formation has been 0.62 g./g. of the polymer. The prepared polymers produced a narrow one‐component signal in the ESR spectrum at spin concentration of 10−7–1019 spins/g. which confirms the presence of conjugated double bonds in the polymers. The electrical conductivity temperature plot obeyed the exponential law. The values of conductivities were 11−12 to 10−8 ohm−1‐cm.−1, and activation energies—0.72‐0.049 e.v.
Die Parakristalline Struktur von Polyäthylen‐Einkristallen
Authors: Calleja F. J. Baltá , Hosemann R. , Wilke W.
Published: September 2014

The increase in integral width of (110), (220) and (330) reflections of linear polyethylene single crystals crystallized from 0.05% n‐xylene solution demonstrates the existence of paracrystalline lattice defects in crystalline regions. The g value describing the statistical distance fluctuations of (110) planes is g = 1.88% and 2.14%, the particle size vertical to the chain direction D = 299 and 331 A., respectively, for Hostalen G and Lupolen 6011‐H, respectively, the two polyethylene materials investigated. It is not possible to explain the increase in line width by the occurrence of lattice strains.
Tracer study of stereospecific butadiene polymerization initiated by rh catalyst in water emulsion
Authors: Sokolov V. N. , Babitskii B. D. , Kormer V. A. , Poddubnyi I. Ya. , Chesnokova N. N.
Published: September 2014

Stereospecific polymerization of butadiene with different rhodium compounds in water medium has been studied using the tracer method. Water is shown to play an active part in both the initiation and termination stages as evidenced by the presence of groups in polymers. The OH−, Cl− polar groups of the polymer are found to be allylic. It has been shown for the case of rhodium‐acetate complex, using the kinetic isotope effect method that termination of polymer chains occurs through water proton addition. A coordinated mechanism through π‐allylic complexes has been proposed for the polymerization of butadiene with rhodium catalysts. It has been assumed that the initiation stage is a π‐allylic complex forming reaction, propagation of polymer chains occurring through the monomer molecules introduction between a metal atom and organic ligand.
Polymerization of butadiene with π‐allylic catalysts
Authors: Kormer V. A. , Babitskii B. D. , Lobach M. I. , Chesnokova N. N.
Published: September 2014

The polymerization of butadiene‐1,3 with π‐allylic nickel complexes has been studied. π‐Allyl(crotyl) nickel halides themselves are shown to initiate stereospecific polymerization. The stereospecificity of the catalysts is determined by the nature of halogen bonded to metal. In the presence of chlorine complexes cis‐1,4‐polybutadienes are obtained, the iodine ones giving trans‐1,4‐polybutadienes.

Lewis acids change the stereospecificity of π‐crotyl nickel bromide and iodide, favoring cis‐1,4‐structure formation.

The polymerization of butadiene with rhodium compounds has been investigated. The experimental evidence indicates that the polymerization involves π‐allylic complexes.

An attempt is made to explain the mechanism of polymer chain unit formation on the basis of π‐allylic structure of active sites in diene polymerization by transition metal compounds.
Contribution à l'Étude du Fluage des Copolymères Polyesters Linéaires Insaturés—Styrolène
Authors: Rosso Jean‐Claude , Persoz Bernard
Published: September 2014

The experiments dealt with a series of succino‐fumarates of diethylene glycol whose crosslinking, obtained by copolymerization with styrene, is adjusted by varying the percentage of fumaric and succinic acids. The overall results in tensile creep in the transition zone have provided for each of the compounds a master curve for creep and a time‐temperature relation of the Williams, Landel, and Ferry type. These master curves may be expressed in terms of general equations function of time, of the number of portions of network chains between two crosslinking junctures and of the percentage in styrene.
Transport of cationic depolarizers through polybase monolayers adsorbed on the mercury surface
Authors: Miller Israel R. , Frei Yael F. , Bach Diana
Published: September 2014

The permselectivity of the ultrathin charged membranes to transport of identically charged ions and the structure of adsorbed polyelectrolyte monolayers from the measured transport was investigated. The ion transport was measured by means of the electrical current resulting from the electroreduction of the cationic depolarizers (Cd++, Cu++), diffusing to the surface. The diffusion of the ionic depolarizers to the mercury surface is impeded by the equally charged layer of polybases to an extent depending on their concentration and their structure in the surface and on the concentration of the supporting electrolyte in the bulk. The impeding effect of the adsorbed polybase monolayers was obtained from the ordinary polarographic diffusion current measurements and also from the current–time curves during the lifetime of single mercury droplets at selected constant potentials. The current–time curves also provide a means for determination of the diffusion coefficients or of the surface concentrations of the polybases.
The kinetics of the polyisoprene formation initiated with lithium organyl
Authors: Sinn H. , Bandermann F.
Published: September 2014

The kinetics of polyisoprene formation have been investigated in n‐heptane, diethylether, and in mixtures of these two solvents. Li‐butyl (LiB) or Li‐poly‐isoprenyl (LiR) was used as an initiator. The time–conversion curves for isoprene [M] are described by the following equations:

and

[LiR] and [LiB] means the concentration of monomer forms of the highly self‐associated Li‐organyls. To evaluate these from the analytically found concentration, equations and functions are given. No ionic picture for the reaction mechanism can be derived from the discussion of the found reaction rates and equilibrium constants. Furthermore, conductivity measurements have been done on Li‐butyl in n‐heptane. The found values for molar conductivity between 10−5 to 10−4 [cm.2/mole‐1 Ω] in the concentration ranges 10−6 to 10−2 [moles/liter] fulfill laws derived for 1 − α ≅ 1 (α = degree of ionic dissociation).
A three‐thermistor ebulliometer
Authors: Daniels T. , Lehrle R. S.
Published: September 2014

Comparison of the performance of one‐, two‐, and three‐thermistor ebulliometers has shown that the three‐thermistor design is preferable. In this apparatus two of the three thermistors are sited in the vapor phase, and the other receives liquid effluent from the vapor‐lift pump. Temperature gradients in the apparatus have been measured, and optimum sites for the thermistors chosen on this basis. Other aspects of design, including that of the vapor‐lift pump, are discussed. This type of instrument allows measurements corresponding to the boiling point of solvent to be repeated even when the boiler contains solution. By this means any effects of drift are eliminated. The sensitivity of the instrument is comparable with that of two‐thermistor instruments (useful molecular weight range up to ca. 40,000, at which the predicted uncertainty is less than 10% for studies up to 2% concentration); the advantage of the design is that measurements are made with greater speed and facility because of improved stability and repro‐ducibility. Examples of the application of the apparatus to some problems of interest in polymer chemistry are included. These include: (a) estimation of solvent of crystallization in diphenylpicrylhydrazyl, (b) an examination of oligomeric products from chloroprene polymerizations, and (c) direct molecular weight measurements on low molecular weight polymers (MW range 1000‐30,000). The results are compared with independent estimations.
Fractionnement et Distribution Moléculaire du Diacétate de Polyoxyméthylène
Authors: Dick Richard , Sack Henri , Benoit Henri
Published: September 2014

The fractionation of a polyoxymethylene, stabilized by controlled degradation with acetolysis, has been carried out by two techniques: fractional precipitation and fractional dissolution. Infrared spectroscopy combined with end‐group analysis and intrinsic viscosity measurements in aniline at 116.5°C. have been used for the identification of the fractions. The results follow a Mark‐Houwink‐Sakurada viscosity law and permit the determination of the molecular weight distribution.
Kinetics of radical polymerization. XVIII. Inhibition of radical polymerization with quinones
Authors: Simándi T. L. , Tüdös F. , Turcsányi B.
Published: September 2014

The inhibitory effect of multiring quinones on the polymerization of styrene was examined. The logarithm of the relative reactivity of quinones also contains, besides a member which reflects the changes in the oxidation‐reduction potential, a member corresponding to the changes in resonance energy which accompany quinoid r̊ benzenoid structural transformation. The observation that the experimental values of the stoichiometric coefficient are generally much smaller than the theoretical ones can be interpreted by the aid of the hot‐radical hypothesis.
The structure and flexibility of stereoregular macromolecules. The model of statistical zigzag chain
Authors: Birshtein T. M. , Ptitsyn O. B.
Published: September 2014

The statistical zigzag chain model is proposed for a description of the conformational properties of macromolecules. The lengths of the segments in such a model are statistically distributed. The short‐range order in regular regions (segments) of chain is similar to one‐dimensional, long‐range order in a crystalline chain, which corresponds to the minimum of the intramolecular potential energy. The equivalence is not completely due to asymmetrical vibrations of monomer units about the positions of energy minimum. The flexibility of the statistical zigzag chain is characterized by the mean length of regular regions and by the relative orientation of the neighboring regular regions. For the macromolecules with the helical short‐range order, the latter is determined by an angle between the axes of the neighboring helical regions. It is shown that comparision of experimental values of mean square end‐to‐end dimensions and dipole moments permit both parameters of the model to be obtained. The results of calculation of the conformational characteristics of isotactic vinyl chains by means of the statistical zigzag chain model are very similar to those of the rigorous theory, based on the matrix method of the Ising model. The relative contributions of rotational isomerization and rotational vibrations to the statistical coiling of chains and to the temperature dependence of their mean dimensions are discussed.