bluuebunny/crossref_metadata_2025_split huggingface dataset:
The polymerization of 1,3‐dioxolane. I. Structure of the polymer and thermodynamics of its formation
Authors: Plesch P. H. , Westermann P. H. 
Published: September 2014

AbstractWe have polymerized 1,3‐dioxolane in our adiabatic reaction calorimeter under vacuum in methylene dichloride with anhydrous perchloric acid as catalyst. We confirm previous findings that the polymer consists of a regularly alternating sequence of “formaldehyde” and “ethylene oxide” units. The polymer prepared in the presence of water has terminal OH groups, but that prepared under strictly anhydrous conditions has no detectable end groups, and we conclude that it is cyclic; we suggest a reaction mechanism involving ring expansion. The polymerization is an equilibrium involving polymer and monomer only, without side reactions. For a one molar solution the ceiling temperature is +1°C., ΔSss° = −18.6 ± 1.2 cal. deg.−1 mole−1: ΔHss° = −5.2 ± 0.2 kcal./mole, direct calorimetric measurements for polymerization and depolymerization, and calculation from d log K/dT giving identical results.
Photoconductivity of vinyl polymers
Authors: Kryszewski M. , Szymański A. , Włochowicz A. 
Published: September 2014

AbstractThe photoconductivity of vinyl polymers: polyethylene (PE), polyvinyl fluoride (PVF), polyvinyl chloride (PVC), and polyvinyl bromide (PVBr) was investigated in different conditions of UV irradiation and electric field strengths. The degree of crystallinity was determined by x‐rays diffraction. The conductivity was investigated in air and in vacuum, by use of classical d.c. measuring set. Semitransparent, vacuum deposited Al electrodes were applied. The PE and PVF exhibit photoconductivity when irradiated with UV light of λ < 260 mμ. It was found that steady state photocurrents Ip were 10–100 times greater than dark currents Id and fulfilled the relation Ip ∼ Vn, where n > 1. The Ip value depends on the polarity of the illuminated electrode. The PVC films showed a slightly negative conductivity. Because of small stability of PVBr against the UV light, the results concerning photocurrents iu this case could not be interpreted. The kinetic studies of growth and decay of photocurrents showed that reaching steady state current depends upon the polarity of illuminated electrodes. The results were discussed in terms of electron mechanism of conductivity and SCLC theory. A tentative interpretation of the occurrence of steady state and of the possibility of the negative photoconductivity was given.
Cationic polymerization of some 1,1‐dialkylethenes and methylenecycloalkanes
Authors: Van Lohuizen O. E. , De Vries K. S. 
Published: September 2014

Abstract2‐Methylbutene‐1, 2‐methylpentene‐1, and 2,3‐dimethylbutene‐1 were polymerized by AlCl3 or AlBr3 catalyst in ethyl chloride or ethyl chloride—vinyl chloride mixtures at temperatures down to —175°C. The glass transition temperatures of the amorphous polymers are −5, 27, and 37°C., respectively. The highest molecular weights—weight averages about 200,000 to 350,000—were found at the lowest polymerization temperature and with monomer—catalyst molar ratios of about 1000 and over. The influence of the addition of the corresponding 2‐methylalkene‐2 was investigated for the polymerization of 2‐methylbutene‐1 and 2‐methylpentene‐1. The other alkenes investigated, viz., 2,3,3‐trimethylbutene‐1, 2,4,4‐trimethylpentene‐1, and 2‐ethylbutene‐1, yielded only small amounts of liquid oligomers. In the polymerization of 2,3‐dimethylbutene‐1 an extensive intramolecular 3–2 hydride shift occurred, varying in amount from 80% at −125°C. to 100% at −175°C., to judge from NMR and infrared spectra. Of the methylenecycloalkanes investigated, only methylene—cyclohexane yielded a high molecular weight polymer—weight average molecular weight about 100,000—although in a yield of only a few per cent, under optimal conditions at −180°C. Methylenecyclobutane gave a semisolid polymer of low molecular weight, methylenecyclopentane a small amount of liquid oligomers, and 2‐, 3‐, and 4‐methyl(methylenecyclohexane) solid polymers of low molecular weight. Poly(methylenecyclohexane) and the polymer from 4‐methyl(methylenecyclohexane) crystallized from solution or upon thermal treatment; the crystalline melting points were about 210 and 195°C., respectively. The relation between structure and ease of polymerization of this type of unsaturated aliphatic hydrocarbon is briefly discussed.
Anomalies de Biréfringence d'Écoulement Presentées par les Solutions Diluées de Quelques Polymères
Authors: Debeauvais Francis , Gramain Philippe , Leray Joseph 
Published: September 2014

AbstractWhen subjected to low shear rates, dilute polymer solutions may display an abnormal behavior, in which the extinction angle does not extropolate to 45° at zero shear rate. A number of systems are discussed. It is shown that these anomalies may be due to a few large particles that have a positive optical anisotropy. The possible origin of these optical impurities is discussed and related to molecular associations or degradation products depending upon the system.
Radiolyse Oxydante du Polystyrolène en Solution Chloroformique Diluée
Authors: Abadie Marc , Marchal Jean 
Published: September 2014

AbstractWe have undertaken the study of radiolysis effects on molecular parameters of polystyrolene irradiated in chloroform solution. We have used samples of molecular weight between 3000 and 1,500,000, which were obtained by radical or anionic polymerization. Experiments show that chain scission rapidly reaches a limit which is a function of intensity and independent of initial molecular weight.
Étude du Poly‐l‐γ‐Glutamate de Benzyl en Hélice par Absorption Dipolaire en Solution
Authors: Marchal Eve , Marchal Jean 
Published: September 2014

AbstractWe propose a method of analyzing dipolar absorption spectra by means of which the relaxation time distribution curve can be determined without making any hypothesis about the shape of the curve. This method has been applied to poly‐l‐γ‐benzyl gluta. mate solutions in three solvents in which the polymer is in a helical form. The variation with molecular weight of the rotatory diffusion constant of these macromolecles when they turn around the smaller axis and their mean square electric moment shows that they do not behave like rigid cylinders.
Préparation et Étude de Complexes à Transfert de Charge Macromoléculaires avec le Poly‐p‐N,N‐Diméthylaininostyrène
Authors: Parrod Jacques , Rempp Paul , Knoesel Roger 
Published: September 2014

AbstractPreparation of macromolecular charge transfer complexes with several micromolecular acceptors—mainly halogenated quinones—and the individual monomer units of poly‐p‐dimethylaminostyrene, which exhibits electron donating properties, is described in this paper. The reaction is carried out in solvents, and its rate depends mainly upon temperature. The obtained complexes can be isolated easily. The amount of acceptor which is linked to the donor chain depends upon the experimental conditions used and is related to the nature of the acceptor. Reference experiments were carried out with dimethylcumidine, a model molecule, and with statistical copolymers of styrene and dimethylaminostyrene. Changes of the absorption spectra during the CTC formation can be explained in terms of interaction between neighboring donor monomer units by means of the coupled acceptor molecules. The electrical conductivity of these macro‐molecular CTC's has been measured. But when the acceptor is a quinone, the obtained values of the conductivity do not differ much from those of the separate constituents of the CTC.
Quelques Aspects du Comportement en Solution des Copolymères Greffés Poly(acrylate d'Éthyle)—Poly(styrène‐Anhydride Maléique)
Authors: Danon Jeanne 
Published: September 2014

AbstractThe solution behaviour of poly(styrene‐maleic anhydride)PSAM‐poly(ethyl acrylate) PAE graft copolymers is studied by osmometry and turbidimetry in acetone and tetrahydrofuranne, solvents for the two constituents, as a function of chemical composition, chemical nature of grafted chains and, topochemical structure. It is shown that such copolymers present original properties depending sometimes on the nature of grafted chains and due to the miscibility of PSAM and PAE.
Calculation of long periods in polymers and determination of the sizes of crystallites and amorphous regions
Authors: Tsvankin D. Ya. , Zubov Yu. A. , Kitaigorodskii A. I. 
Published: September 2014

AbstractFor the interpretation of long periods of oriented polymers, a calculation was carried out of scattering along the meridian of a small‐angle x‐ray texture diagram. In the calculation a scheme of the structure of a fibril was used, consisting of crystalline and amorphous regions. It was assumed that the crystallite center was statistically distributed along the fibril. The density distribution within a crystallite is given. For the interpretation of the experiment, several calibration graphs were obtained from theoretical curves. Wide‐ and small‐angle x‐ray diffractions were measured for a number of samples of polyethylene fibers and capron films. The sizes of crystallites and amorphous regions along the fibril axis were determined with calibration curves. These results are compared with the size of crystallites and crystallinity determined from wide‐angle diffraction and density.
La Réticulation: Un Aspect Particulièr de la Gélification Selon la Theorie des Graphes Stochastiques
Authors: Bruneau Claude M. 
Published: September 2014

AbstractThe stochastic graph theory has been applied to define axiomatically intermolecular and intramolecular reactions, as well as the phenomenon of gelation, equations for determining the date of appearance of the phenomenon, and its domain for three topologically possible principle types of systems have been given. The experimental values for gel points in structurally different systems, being in good agreement with the theoretical (±1 to 2%), lead us to conclude that the observed slight differences near the limiting conditions of the domain are certainly due to a non‐equiprobable behavior of steric origin. Assimilating crosslinking (and also vulcanization) to a process of gelation taking place in two distinct and successive phases seems to lead to results in conformity with the idea of evolution and with the values of characteristic magnitudes of these techniques in as much as their experimental conditions are not much different from those theoretical herein admitted.
Zur Frage der Abhängigkeit der Relaxationszeit des dielektrischen Verhaltens der Polymeren vom freien Volumen
Authors: Kästner S. 
Published: September 2014

AbstractIn the discussion of temperature dependence of dielectric behavior in the main relaxation process very often the WLF equation is used, which can be explained by the theory of the free volume. The purpose of the paper was to prove directly the influence of the free volume, which seems possible by measurements of the dielectric behavior in the vicinity of the glass transition temperature during the isothermal volume contraction. The results show that the mean relaxation time is a function of free volume. Furthermore, it was found that the width of the relaxation spectrum is a function of free volume also. On the other hand it must be noted that the mean relaxation time, beside the dependence of free volume, shows little direct temperature dependence.
Radiation‐induced polymerization of gaseous ethylene. I. Role of some impurities on polymerization
Authors: Munari S. , Russo S. , Castello G. , Rossi C. 
Published: September 2014

AbstractSome experiments on ethylene polymerization under pressure by gamma rays were carried out at room temperature with research grade purity monomer used. No induction period was noticed in these conditions; high conversion rates were obtained with good evidence for autoacceleration reactions. Stationary state kinetics were applied in the first step of the reaction, and rate constants were calculated. The product was a linear or long‐branched polyethylene; no double bond was found by infrared analysis. Molecular weights increased with decreasing intensity and with increasing total absorbed dose. The influence of oxygen on the polymerization of ethylene, in the range from 10 to 1000 ppm, was also studied. The induction period increased with the oxygen concentration, but no linear relationship was found between induction time and oxygen concentration. After the induction period the polymerization took place at lower rates than pure ethylene, supporting a retardation effect of peroxidic species formed. Also investigated was the influence of added acetylene, which is also a primary product of the ethylene radiolysis, in a wide range of acetylene—ethylene ratios. The behavior of the system depends upon acetylene concentrations. At low concentrations, acetylene acts as a retarder and as a chain transfer agent, producing a decrease of yields and of molecular weights. A possible mechanism for the interaction of acetylene with chain radicals is proposed.
Gasses evolved by 60Co radiation degradation of strongly acidic ion exchange resins
Authors: Mohorčič Gorazd , Kramer Vili 
Published: September 2014

AbstractThe irradiation damage and stability of polystyrene—divinylbenzene and phenol—formaldehyde sulfonic acid ion exchange resins was investigated by determination of the radiolytic gases. A 440 curies 60Co radiation source was used. Commercial resins, Dowex 50W ×10 and Zeo‐Karb 215, were prepared under strict conditions in free acid and in salt forms, in an excess of deaerated water, swollen with a known amount of water, and in a very dry state. A series of 6 equal samples were exposed to absorbed doses of 50–200 Mrad at a dose rate 2.5 × 105 rad/hr. The gas analysis shows a very good linear does dependence of the evolved hydrogen and carbon monoxide. The linearity of carbon dioxide is good for Dowex 50W X10 but less pronounced for Zeo‐Karb 215. Sulfur dioxide is at least partially produced by direct action and is consumed by secondary reactions during irradiation.Under chosen experimental conditions the evolved hydrogen amounts for the absorbed dose 1 Mrad from 0.3 to 670 μmoles H2/eq. resin. The values for carbon dioxide and carbon monoxide are: 1.4–170 μmoles COs/eq. and 0.4–5.3 μmoles CO/eq. The corresponding G values are: 0.001–1.7 for hydrogen, 0.007–0.43 for carbon dioxide, and 0.002–0.027 for carbon monoxide. The G values for sulfur dioxide, calculated from the lowest absorbed doses, are between 0.001 and 0.87.
Structure and rheological properties of polymer mixtures
Authors: Natov M. , Peeva L. , Djagarova E. 
Published: September 2014

AbstractInvestigations were undertaken of the structure and rheological properties of mixtures consisting of one crystallizing and one amorphous polymers. It was established that mixtures of poly(ethylene adipate) and poly(vinyl acetate); of poly(ethylene adipate) and poly(methyl methacrylate); and of poly(ethylene sebacinate) and poly(methyl methacrylate) can form amorphous solid solutions with one another or can crystallize without any apparent division of the two components. The phase condition of the mixture is determined by the nature of the two polymers, by the ratio between them, and by their molecular weights. The melting point of these mixtures drops in proportion to the content of the amorphous component. The assumption is made on the basis of the results obtained that the amorphous component occupies the defective areas in the crystal grating. The fluidity of the mixtures was measured by means of a capillary viscosimeter. It was established in all cases that there appear deviations from the proportional change of the effective viscosity between the viscosities of the components. These deviations are explained by the change in the energy of activation of the viscous flow of the melts which was also subject to determination.
Étude sur la Copolymérisation Radiochimique en Phase Solide de l'Anhydride Maléique avec Certains Dérivés de l'Acrylamide
Authors: Zurakowska‐Orszagh Janina , Wojno Teresa 
Published: September 2014

AbstractOur first data concerning the radiochemical copolymerization in the solid state, as well as those of other authors are usually related with systems forming mixed crystals. In the present study the copolymerization in the solid state initiated by γ‐rays has been examined in the case of binary systems composed of maleic anhydride with a homologous series of acrylamide derivatives giving eutectic mixtures. The choice of the anhydride was based on its low homopolymerization tendency particularly in the solid state even at high irradiation doses, as has been controlled. The other component was acrylamide, N‐tert‐butyl‐acrylamide, N‐tert‐amyl‐acrylamide, N‐tert‐hexylacrylamide, N‐tert‐heptyl‐acrylamide which polymerize in the solid state. The rate of cooling of the fused mixtures of the components exerts a marked influence on the degree of conversion after irradiation. The highest content of maleic anhydride in the copolymer was found for the system maleic anhydride—acrylamide.
Polymérisation de l'Acrylonitrile dans un verre de Méthyltétrahydrofuranne a Basse Témperature
Authors: Bodard‐Gauthier Monique , Marx Rose 
Published: September 2014

AbstractThe polymerization of acrylonitrile in methyltetrahydrofuran glass irradiated with γ rays at − 196°C. has been studied. Such a medium has been chosen because it can trap ions and electrons, therefore it is able to favor an ionic polymerization. Polymer yield versus monomer concentration presents a maximum at about 15% monomer. The influence of some additives on polymer yield and the composition of copolymers obtained in the presence of methylmethacrylate show that here acrylonitrile polymerization proceeds through an anionic mechanism. The radicals formed under irradiation and the ions responsible for polymerization were observed by ESR and absorption spectroscopy.
Nature of stereoregular butadiene polymerization initiated by ionic coordinated catalysts
Authors: Bresler L. S. , Poddubnyi I. Ya. , Sokolov V. N. 
Published: September 2014

AbstractA radioactive tracer method for distinguishing between cationic and anionic polymerization mechanism is described. The evaluation of the mechanism involves the terminating of polymerization by alkoxyl‐labeled or oxygen‐tritiated alcohols and carboxylation of active sites. The limitations of the technique were estimated by applying it to catalysts of established cationic and anionic activity. The TiI4—AlR3 was demonstrated to initiate a coordinated anionic polymerization of butadiene, whereas soluble cobalt complexes catalyze a coordinated cationic propagation. The discrepancies in results of previous studies applying alcohol termination to cobalt catalysts are interpreted. Applying the Cl36‐labeled AlR2Cl and/or CoCl2 the chlorine was demonstrated to incorporate into the polymer chain in the course of polymerization, and a mechanism is suggested involving a secondary cationic process catalyzed by excess AlR2Cl.
On two‐step copolymerization
Authors: Frunze T. M. , Kurashev V. V. , Baranov E. L. 
Published: September 2014

AbstractThe method for two‐step copolymerization is developed to obtain carbo‐hetero‐chain copolymers. The method combines processes, proceeding by various mechanisms (radical and ionic), and consists of simultaneous or subsequent action of the catalyst of both types. In the case of the subsequent addition of the catalyst to the initial reagent mixture, the anionic grafting of ∈‐caprolactam to the polymer that is formed at the initial stage of the process and is a macromolecular initiator of the anionic polymerization takes place. Principal regularities of the copolymerization of ∈‐caprolactam with vinyl monomers (in particular, with styrene) have been studied.
Die Kinetische Untersuchung des Abbaus von Carboxymethylcellulose durch Cellulase
Authors: Werner R. 
Published: September 2014

AbstractThe usual viscosimetric assay of cellulase activity with partially substituted carboxymethyl celluloses (CMC) yields only relative enzyme units. It is not suitable for characterizing different cellulose enzymes. By means of sedimentation and diffusion measurements the viscosity‐molecular weight relationship of CMC was determined. With this relation and by using the number average molecular weight of the CMC used as substrate, it is possible to conclude from the decrease in viscosity the number of glucosidic bonds split. With this improved and extended viscosimetric method the activity of cellulose is measured directly in international enzyme units, in μmole glucosidic bonds split/min. Moreover, kinetic parameters such as the Michaelis constant and turnover of the enzyme can be determined. The usefulness of this assay method is demonstrated with a cellulose from Acetobacter xylinum.
Conformation analysis of isotactic polystyrene
Authors: Liquori A. M. , De Santis P. 
Published: September 2014

AbstractThe potential conformational energy of isotactic polystyrene has been calculated as a function of the angles of rotation around the three non‐equivalent bonds in the monomeric unit. The calculations have been carried out using semi‐empirical potential functions to describe the van der Waals pair‐wise interaction between nonbonded atoms‐according as in previous work. The deepest minimum of the three dimensional potential energy map corresponds to a helix with 3.1 number of monomers per turns and a monomer repeat on the helical axis 2.2 A. in good agreement with that established experimentally for crystalline polymer by x‐ray analysis.
Dien Polymerisation mit Komplex‐Katalysatoren. III. Beschränkung des katalytischen Einflusses der Titanverbindungen bei dem oxydativen Abbau des cis‐1,4 Polyisoprens
Authors: Rosík Ladislav , Svoboda Václav , Zikmund Miroslav 
Published: September 2014

AbstractThe effect of titanium compounds on the oxidative degradation of cis‐1,4‐polyisoprene has been widely restricted by transformation of titanium to its tetravalent form and by its stabilization in the higher valency state. With regard to the oxidative degradation of polymer, titanium(IV) oxide and titanium(IV) complex with hydrazine can be considered inactive compounds. The peroxidic intermediate products and the free radicals which are formed by oxidation of titanium(III) chloride and of the organoaluminum components of the Ziegler catalyst initiate the oxidative degradation and the crosslinking of the polymer. Mechanism of the decomposition of the Zeigler catalyst by oxygen, lead(IV), acetate, or hydrazine has been proposed.
Polymères Thermostables. III. Les Polycétoquinoléines
Authors: Sillion Bernard , De Gaudemaris Gabriel 
Published: September 2014

AbstractPolyketoquinolines are obtained by using a variation of the Von Niementowski reaction. A prior examination of the simple anthranilic esters on the dioxolane of acetophenone shows that ethyl esters are much more suitable than methyl esters. A reaction was then set up between bisanthranilates (such as 2,5′‐diaminoethyl terephthalate and 4,4′‐diamino 3,3′‐ethyl diphenyl dicarboxylate) and bisdioxolanes derived from diketones (such as diacetyl benzenes, 4,4′‐diacetyl phenyl oxide or 4,4′‐diacetyl diphenyl). Various solvents such as phenyl oxide, metacresol, are used at their reflux temperature. The inherent viscosities in formic acid of the polymers thus obtained are of interest. Like their monomers, the polymers appear to exist in the solid state in a ketoquinoline form as shown by the infrared spectrum. Thermogravimetric analysis, from ambient temperature to 550°C. in argon atmosphere, recorded at a rate of 60°C./hr., shows a decomposition of 5%.
Modification de Polymères Insaturés par Époxydation
Authors: Roux C. , Pautrat R. , Cheritat R. , Ledran F. , Danjard J. C. 
Published: September 2014

AbstractConditions of epoxidation of unsaturated polymers were studied. Perphthalic monoacid appeared to be one of the most efficient epoxidation agents, particularly when the double bond is enriched with electrons. Some properties of the new polymers thus obtained were revealed and functional crosslinkings were achieved.