bluuebunny/crossref_metadata_2025 huggingface dataset:
The theory of dielectric losses in amorphous polymers in the high‐temperature range (above glass‐transition point)
Authors: Gotlib Yu. Ya.
Published: September 2014

Simple molecular models are proposed to explain the sharp decrease of the apparent activation energy Uα for the α relaxation process, observed in amorphous polymers in the high‐temperature region (50–100°C. above Tg). The intermolecular interaction in amorphous polymer is divided into collective and localized parts. The collective part is characterized by a large temperature coefficient. The α process includes the transition over the local potential barriers, which determines the rate of the β process. The sharp decrease of Uα occurs when the collective part of the interaction is weak; i.e., when the local potential barrier determines the net rate of the relaxation process. One of the models also explains the decrease in the magnitude of α absorption with increasing temperature observed in some polymers. The theory predicts a marked variation in dielectric relaxation properties as a consequence of kinetic factors alone, in the absence of any structural (phase) transitions.
Study of the movements of cycloalkyl side groups in polymethacrylates by dynamic mechanical measurements
Authors: Heijboer J.
Published: September 2014

Damping and modulus have been measured in shear at about 1 Hz and in flexure at about 1000 Hz for polycyclopentyl methacrylate (PCPMA), polycycloheptyl methacrylate (PCHpMA), and polycyclooctyl methacrylate (PCOcMA), in the glassy region. The results are compared with those for polycyclohexyl methacrylate (PCHMA). All the cycloalkyl rings show a pronounced damping peak at low temperature. As a function of n the flexibility increases in the order 6 < 8 ≪ 7 ≪ 5. The corresponding apparent activation energies of the movements, in the same sequence, are 11.5, 10.5, ca. 6, and < 4 kcal./mole. The width of the relaxation spectrum increases in the order: 6 < 8 < 7.
The models of the denaturation of globular proteins. I. Theory of globula–coil transitions in macromolecules
Authors: Ptitsyn O. B. , Kron A. K. , Eizner Yu. Ye.
Published: September 2014

The theory of long‐range interactions in macromolecules is proposed for the region where the attraction forces predominate (that is below τ‐point). In an approximate analytical variant of the theory the free energy of segment–segment interactions is calculated without taking into account their bonding in the single chain, that is, by means of strict and approximate equation for the free energy of interaction of real gas molecules. The theory predicts that under some conditions the macromolecule undergoes below the τ‐point, during the change of temperature or solvent composition, the first‐order phase transition from the statistically coiled state to the compact (globular) state. The transition predicted by the theory is similar to the condensation of the real gas cloud to the liquid drop. This result is confirmed by the more strict Monte Carlo calculation which takes into account the bonding of the segments in a single chain. This calculation not only confirms the existence of a drastic compression of the macromolecule, when the attractive forces between its segments increase, but show also that, in the transition region, the macromolecules divide into poorly coiled chains (statistical coils) and highly coiled chains (globula), which directly prove the phase character of the transition. In common macromolecules the “intramolecular condensation” predicted by the theory must occur near to the point of intermolecular condensation so it is difficult to observe it experimentally. However, in macromolecules containing both lyophobic and lyophilic groups the intramolecular condensation may well occur due to the mutual attraction of lyophobic groups and lyophilic groups covering the surfaces of obtained globulas may prevent them from aggregation. In these macromolecules one can observe the intermolecular globula–coil phase transitions by changing the temperature or the solvent composition. It is most likely that the denaturation (and renaturation) of the globular proteins are the examples of such transitions.
The models of the denaturation of globular proteins. II. Hydrophobic interactions and conformational transition in polymethacrylic acid
Authors: Anufrieva E. V. , Birshtein T. M. , Nekrasova T. N. , Ptitsyn O. B. , Sheveleva T. V.
Published: September 2014

To model the compact structures of globular proteins and the processes of their breakdown, the local compact structures have been investigated in the nonionized (or weakly ionized) molecules of polymethacrylic acid (PMA) in aqueous solutions. The potentiometric titration curves differ markedly from the analogous curves for polyacrylic acid (PAA) and show the existence of the cooperative breakdown of the local compact structures in a definite region of the ionization degree. The presence of the local compact structures in the PMA molecules is also manifested in sharp differences between the luminescent characteristics of the dyes (auramine and acridine orange) in aqueous solutions with PMA and the same characteristics in aqueous solutions with PAA. In a certain range (which coincides with the interval of the breakdown of local compact structures) these differences disappear. This permits us to interpret them as the result of the dye molecules binding on the structurized parts of PMA. The assumption has been made that the local compact structures in the PMA molecules in aqueous solutions are stabilized by the hydrophobic interactions of methyl groups. This assumption explains the abnormal temperature dependencies of the properties of the aqueous solutions of PMA and the absence of the local compact structures in the PMA molecules in methanol as well as in the PAA molecules in any solvents. To check this assumption we have investigated the breakdown of the local compact structures in the PMA molecules when aliphatic alcohols are added to the aqueous PMA solution. It was shown that the transition of dye molecules from the bound state to the free one (which is the evidence of the breakdown of the local compact structures) takes place in the narrow range of alcohol concentrations decreasing in the series methanol–ethanol‐propanol–butanol. It means that alcohol destroys compact structures the better, the more hydrophobic groups it possesses. The investigations of intrinsic viscosity of PMA in the water–methanol mixtures have shown that the addition of alcohol leads not only to the breakdown of the local compact structures, but also the unfolding of the macromolecule as a whole. The analogy between the local compact structures in PMA molecules and the compact structures of globular proteins has been discussed.
Ion binding by polystyrenesulfonic acidX
Authors: Dolar D. , Špan J. , Pretnar A.
Published: September 2014

Transference experiments and conductivity measurements carried out with solutions of polystyrenesulfonic acid are reported for the concentration range from 0.005 to 0.15 base molar. From these data the transport number and the ionic conductance of the polyion and the fraction of free hydrogen ions have been calculated. The transport, number and the ionic conductance of the polyion decrease with increasing concentration, whereas the fraction of free counterions increases from 0.38 to 0.58 in the range of concentration mentioned above. Furthermore, the fraction of free hydrogen ions obtained in this work is compared with the corresponding results of pH measurements and with osmotic coefficients. It was found that the fraction of free counterions calculated according to the theory of Katchalsky et al. is in good agreement with the experimental results.
Electron spin resonance studies on ziegler‐catalyst systems. Part IV. On the mechanism of the reduction of titanium (IV) halides with aluminum alkyl halides and the polymerization of ethylene
Authors: Adema E. H.
Published: September 2014

Electron spin resonance measurements on the systems TiCl4(Al(C2H5)Cl2)2, TiCl3‐CH3(Al(C2H5)Cl2)2, and TiCl4(Al(C2H5)2Cl)2 have revealed the formation of a particle with an unpaired electron, S, the concentration of which could be continuously followed with time. The kinetics of the former two systems are estimated and a mechanism for the reduction of the Ti(IV) compounds is proposed. It is shown that the concentration of the unpaired electrons equals the concentration of trivalent titanium in solution. The rate of polymerization of ethylene with the catalyst TiCl4 (Al(C2H5)2Cl)2 proves to be proportional to the concentrations of unpaired electrons. The structure of the particle carrying the unpaired electron is probably a complex consisting of TiCl3 and the dimer aluminum alkyl chloride.
Photogeneration of charge carriers in acetylenic polymers and its sensitization by dyes
Authors: Mylnikov V. , Terenin A.
Published: September 2014

A significant inner photoeffect in organic polymers with triple bonds R+CCR1CC+nR, and the metal polyacetylenides RCCM has been found and investigated by means of direct‐current photoconductivity and photoelectromotive force in intermittent light. The dependence of the photocurrent on the light intensity can be expressed by the equation iph ≐ αLn, where 0.5 < n < 1. The photocurrent relaxation in the range of 10−5 sec. to several minutes displays a second‐order process. Ohm's law is not obeyed. The absorption spectra have been compared with those of photoconductivity, photoelectromotive force, and luminescence. Preliminary short‐ultraviolet irradiation increases the photosensitivity; this is ascribed to bond rupture and electron‐trapping. The latter is confirmed by ESR measurements. Upon evacuation the dark conductivity and the photoconductivity are increased by 3 and 2 orders of magnitude, respectively, and the photoelectromotive force by 5. Oxygen and water vapor reversibly depress the dark and photoconductivity. A photodesorption of oxygen from the surface of metal polyacetalinide can be surmised. Electron acceptors (quinone, chloranil) and mercury vapor have a significant influence on the semiconduction. The photoeffect in the polymers can be spectrally sensitized by various adsorbed dyes. The proper sensitivity is equally changed on dye adsorption. The mechanism of the effects observed is discussed.
Conformations and molecular structure of the chains with (C—O)nbackbone
Authors: Oleinik E. F. , Enikolopyan N. S.
Published: September 2014

Conformations of linear chain molecules of X(CH2O)nX type were studied by infrared spectra of polyoxymethylenes (POM) and oligomers of CH3O(CH2O)nCH3type (n= 3–8). The study was performed at broad ranges of temperature (−80°C.– +200°C.). Infrared spectra of liquid oligomers point at preference of the helical conformation for these compounds.

Bands of unstable isomers were found which disappeared under “freezing up” conditions. The results are the following: (a) the helical conformation of the isolated polyacetalic backbone molecules are the most advantages; and (b) rotational isomerism in these chains exists.
Synergistic stabilizer systems for the protection of polypropylene from thermal oxidation
Authors: Geleji F. , Holly Z. , Ocskay G. , Wein T.
Published: September 2014

The antioxidative behavior of 2,2′‐bis(4‐methyl‐6‐tert‐butylphenols) in polypropylene were investigated with and without dilauryl‐thio‐dipropionate. The experimental methods used in this study were thermogravimetric analysis for determining sample weight loss and differential thermoanalysis for obtaining information on oxidative processes and induction periods. The best antioxidant found was the dithio group bridged compound. The methylene‐, n‐butylidene‐, cyclohexylidene‐, and thio‐bridged systems were less active antioxidants. All compounds showed synergism with DLTP. The effectiveness of the synergistic mixtures decrease with decreasing activity of the bisphenol compounds. The pure dithio‐bridged compound was a better antioxidant in polypropylene than is its “synergistic” mixture with DLTP.
Bipolar electrolyte exchange resins. IV. Electric regeneration
Authors: Mikes J. A. , Haklits J.
Published: September 2014

It has been demonstrated that electric regeneration of so‐called bipolar electrolyte exchange resins into the H+OH− form may take place between permselective ion‐exchange membranes provided that the resin was placed in an aqueous medium. The level of regeneration of cation and anion capacities depends on the ratio of the amount of cationic and anionic active groups \documentclass{article}\pagestyle{empty}\begin{document}$ \[\underline{\underline + } \] $\end{document} index in the resin. In resins of ± > 1 type the cation exchange capacity in H+ form—expressed in percentage of total cation exchange capacity—is constantly higher than the anion exchange capacity in OH− form, /expressed in the same way/ while in the case of \documentclass{article}\pagestyle{empty}\begin{document}$ \[\underline{\underline + } > 1\] $\end{document} < 1 type resins the situation is inversed. An explanation has been given for the mechanism of this phenomenon. A method has been elaborated for the determination of H+ and OH− capacities simultaneously.
Dynamic mechanical properties and impact strength
Authors: Heijboer J.
Published: September 2014

Impact strength and damping as functions of temperature have been compared for eight polymers with typical differences in damping behavior, viz., four methacrylate polymers, a polyphenylene oxide, a polycarbonate, a polyoxymethylene, and a rigid polyethylene. If a damping maximum is caused by a movement within the main polymer chain, it is generally connected with an appreciable increase in impact strength. The temperature of the mechanical damping maximum and that of the transition in the impact strength may, however, differ considerably. If the damping maximum is caused by movements of sidechains only, it has at most a slight influence on the impact strength. Also a polymer with very low damping can have high impact strength and can even show a brittle‐tough transition. This occurs in the case of polyphenylene oxide.
Photoréticulation de Polyacroléines et de Copolymères Greffés d'Acroléine Préparés par Voie Anionique
Authors: Golé Jean , Calvayrac Henri
Published: September 2014

The polyacroleins were prepared anionically in the presence of a sensitizor containing carbonyl groups and irradiated in solution with a mercury vapor lamp. The polymers obtained after various polymerizing times were completely insoluble in organic solvents. Different factors affecting gelation speed were studied. New acrolein graft copolymers prepared from a polycarbanionic polymer are also described. These new copolymers are also crosslinked by light and their use as a photosensitive layer is described.
Hydrogen iodide cocatalysis in iodine‐initiated polymerization of styrene
Authors: Giusti P. , Andruzzi F.
Published: September 2014

The cocatalytic effect of hydrogen iodide on the polymerization of styrene by iodine has been studied. The kinetics of this system have been followed by a dilatometric technique at 30°C. in (CH2Cl)2 solutions. The initial hydrogen iodide concentration has been varied for each iodine concentration from 1/10 up to twice the iodine concentration. The polymerization shows no acceleration period and the rate increases with increasing hydrogen iodide concentration for each given iodine concentration. The molecular weight of the polymers obtained decreases as the acid concentration increases. A reaction mechanism has been proposed.
Preparation and three‐dimensional polymerization of polyester methacrylates
Authors: Mihailov M. , Budevska H. , Nenkov G. , Gerdjikova S.
Published: September 2014

Two methods for the preparation of polyester methacrylates are described: (1) Methacrylation of hydroxy containing oligoesters obtained by the reesterification of the esters of alcohols and polyhydric acids with polyhydric alcohols. Terephthalic, furan 2,5‐dicarboxylic, and benzylphosphonic polyester methacrylates, which cannot be obtained by means of condensation telomerization, are synthesized by this method. (2) Addition telomerization of mixtures of epoxy compounds with anhydrides of methacrylic and polyhydric acids. A closer study of this reaction revealed that it permits the preparation of a wider range of polyester methacrylates than does condensation telomerization. The three‐dimensional polymerization of some of the synthesized polyester methacrylates was investigated.
Internal plasticization of bisphenol‐a polycarbonate
Authors: Conix A. , Jeurissen L.
Published: September 2014

It is well known that crystallization of poly[2,2‐bis(4‐hydroxyphenyl) propane carbonate] by thermal treatment is a slow process. In order to achieve equilibrium crystallization extent, heating for very long periods of time (8 days) at high temperatures (180°C.) is required.1 The rate of crystallization of polycarbonate can be increased by swelling the polymer in suitable solvents such as xylene and acetone.2 In a previous article,3 an extensive study was made of the crystallization behavior of polycarbonate plasticized with tricresyl phosphate. It was shown that the addition of small amounts of plasticizer markedly increases the crystallizability of the polycarbonate. It is the purpose of this study to investigate the possibility of increasing the crystallizability of polycarbonate by internal plasticization achieved by incorporating small amounts of flexible repeat units into the polymer chain through copolycondensation. At the same time, the thermal properties of the copolymers will be discussed.
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

We 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

The 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

2‐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

When 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

We 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

We 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

Preparation 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

The 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

For 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

The 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

In 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

Some 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

The 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

Investigations 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

Our 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

The 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

A 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

The 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

The 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

The 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

The 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

Polyketoquinolines 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

Conditions 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.
Synthèse de Copolymères Séquencés dont une Séquence est un Polypeptide
Authors: Spach Gérard , Reibel Léonard , Loucheux Marie‐Henriette , Parrod Jacques
Published: September 2014

Copolymers containing three sequences (A–B–A), where A represents a polypeptide chain, have been prepared by using a polymer B as initiator of the polymerization of N‐carboxy anhydrides of α‐aminoacids (NCA). At its extremities, B must consist of functions which are capable of promoting the polymerization by attaching themselves to the polypeptide chain. The molecules of polyoxyethylene α,Ω‐diamine, for example, respond to these conditions. The existence of the copolymer is demonstrated by fractionation curves. The study of the initiatory reactions of NCA thus showed that the monoesters of carbonic acid (ROCO2–Na) are interesting endgroups.
Psychosocial outcomes of e‐feedback of radiotherapy for breast cancer patients: a randomized controlled trial
Authors: Siekkinen Mervi , Pyrhönen Seppo , Ryhänen Anne , Vahlberg Tero , Leino‐Kilpi Helena
Published: September 2014

Objective

This study aims to test the effectiveness on psychosocial outcomes of electronic feedback knowledge of radiotherapy intervention (e‐Re‐Know) for breast cancer patients.

Method

Randomized controlled trial in one university hospital in Finland was carried out. Breast cancer patients (n = 126) in the radiotherapy (RT) department were randomly assigned into two groups: intervention (the e‐Re‐Know and standard education) and control group (standard education). The e‐Re‐Know intervention consisted of e‐feedback after response to the knowledge test delivered by e‐mail. Instruments were completed before commencing first RT (M1), after concluding last RT (M2) and 3 months after last RT (M3). The main outcomes were anxiety and QOL.

Results

Compared with the control group, the patients in the intervention group reported a marginally significant improvement in anxiety and significant improvement in QOL over time.

Conclusion

The e‐Re‐Know seems to have positive effects on psychosocial outcomes for breast cancer patients. They might gain additional value from the e‐Re‐Know over a longer time period. Further research needs to focus more on development of e‐feedback in patient education. Copyright © 2014 John Wiley & Sons, Ltd.
Energy‐transfer in porphyrin‐ functionalized graphene
Authors: Malic Ermin , Appel Heiko , Hofmann Oliver T. , Rubio Angel
Published: September 2014

We present a theoretical study on the molecule–substrate interaction within the porphyrin‐functionalized graphene. Recent experiments on porphyrin‐functionalized carbon nanotubes have revealed an extremely efficient energy transfer from the adsorbed molecules to the carbon substrate. To investigate the energy transfer mechanism, we have characterized the hybrid structure within the density functional theory including the calculation of the molecular transition dipole moment, which allows us to determine the Förster coupling rate. We find a strongly pronounced Förster‐induced energy transfer in the range of fs confirming the experimental observations.

Side view on the graphene layer non‐covalently functionalized with a porphyrin molecule.
Transforming circumnavigating Kelvin waves that initiate and dissipate the Madden–Julian Oscillation
Authors: Haertel Patrick , Straub Katherine , Budsock Andrew
Published: September 2014

Analyses of Lagrangian model simulations and atmospheric sonde data reveal a key component of the Madden–Julian Oscillation (MJO): circumnavigating equatorial Kelvin waves with dynamics that transform between dry and moist, which initiate and dissipate MJO convection. The same compositing procedure is applied to simulated and observed MJOs, which uses a coordinate system that moves with the precipitation centre, and treats developing, mature and dissipating stages separately. MJO structure and evolution are similar in the simulation and the observations. To the west of the developing convection, there is a broad region of low‐level (upper‐level) perturbation westerlies (easterlies), which is accompanied by a deep negative temperature perturbation. As this feature enters the MJO‐formation region, convection intensifies on its eastern edge, and the zonal wind perturbations decrease in zonal extent and propagation speed. This process is shown to be a dynamical consequence of a largely dry, first baroclinic Kelvin wave entering a region where large‐scale upward motion is mostly balanced by convective heating. As the MJO matures, a Kelvin wave of opposite sign emerges from its eastern edge, and makes the opposite transition (from moist to dry). The resulting wave, which includes low‐level (upper‐level) easterlies (westerlies) and a deep positive temperature perturbation, rapidly propagates around the world and dissipates MJO convection. The Kelvin wave that initiates MJO convection is shown to originate from the inactive phase of a previous MJO, so that the complete MJO cycle is characterized by the two kinds of Kelvin waves emerging from active and suppressed phases of MJO convection, circumnavigating the Tropics, and triggering the opposite phase.