bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature dependence of the optical activity of nicotine salts of poly(methacrylic acid) in dilute aqueous solutions
Authors: Mihailov M. , Baldzhieva R. 
Published: June 2010

AbstractThe influence of temperature on the optical activity of dilute aqueous solutions of nicotine salts of poly(methacrylic acid) as well as of nicotine and the nicotine salt of pivalic acid has been studied. It was found that the temperature dependence of the optical activity is nonlinear, and reflects changes in structure and proteolytic equilibria in solutions. The variation of the temperature coefficient of optical activity of the solutions and its dependence on concentration and wavelength are discussed.
Light scattering of concentrated polydisperse polymer solutions
Authors: Scholte Th. G. 
Published: June 2010

AbstractOn the basis of the Smoluchowski‐Einstein‐Zernike theory, it is shown that light‐scattering measurements on mixtures can, in general, yield information about the second derivatives of the free enthalpy (Gibbs free energy) of mixing with respect to the concentrations. This method can be applied to concentrated solutions of polydisperse polymers or polymer mixtures. Integration of the appropriate experimental data yields the chemical potentials and the interaction parameters. From the same theory it follows that plotting of the reciprocal of the scattered‐light intensity versus the temperature for a number of compositions, and extrapolation to zero yields the spinodal. This procedure does not initiate from any particular molecular model. It can be applied to simple polymer solutions, but equally well to more complicated systems such as two polymers in one solvent or a mixture of two or more polymers. Spinodals have been determined for solutions in cyclohexane of three polystyrene samples with the same weight‐average molecular weight but differing in their width of distribution.
Phase separation in polymer solutions. II. Determination of thermodynamic parameters of poly (2,6‐dimethyl‐1,4‐phenylene oxide) toluene mixtures
Authors: van Emmerik P. T. , Smolders C. A. 
Published: June 2010

AbstractIn liquid systems where it is possible to perform light scattering experiments at the melting points of polymer solutions without nucleation taking place because of undercooling, the thermodynamic parameters necessary to calculate the correction parameter g in the Flory‐Huggins equation as modified by Koningsveld can be determined. In the system poly(2,6‐dimethyl 1,4‐phenylene oxide)‐toluene crystallization will be induced by liquid‐liquid phase separation at temperatures below the melting points. The Huggins interaction parameter x, calculated from light scattering data, shows negative values for solutions up to 24.5 weight per cent of polymer. This indicates specific interactions between polymer and solvent molecules. A combination of data from light scattering and from calculations based on the theory of melting point depression affords the values necessary for calculating the free enthalpy of mixing ΔG.
Antioxidants and stabilizers. XL. Contributors to the thermal decomposition of tert‐butyl hydroxyperoxide
Authors: Zikmund L. , Janota J. , Brodilová J. , Pospíšil J. 
Published: June 2010

AbstractThe rate of decomposition of tert‐butyl hydroperoxide in benzene solution within the temperature range of 132 to 170°C has been investigated. At concentrations of tert‐butyl hydroperoxide lower than 0.03 mole/1. the reaction occurs via a monomolecular mechanism (activation energy Eb = 36.7 ± 3 kcal/mole). At higher concentrations the initial rate of decomposition is that of a second‐order reaction with respect to hydroperoxide (activation energy Ea = 16 ± 4 kcal/mole). The reaction mechanism has been discussed, and the activation energy of the reaction of tert‐butoxyl radicals with tert‐butyl hydroperoxide has been estimated.
Antioxidants and stabilizers. XLI. reaction of tert‐butyl hydroperoxide with 2,2′‐methylenebis(4‐methyl‐6‐tert‐butylphenol)
Authors: Zikmund L. , Brodilová J. , Janota J. , Pospíšil J. 
Published: June 2010

AbstractThe reaction of tert‐butyl hydroperoxide with 2,2′‐methylenebis(4‐methyl‐6‐tert‐butylphenol) in a benzene solution was studied within the temperature range 132 to 170°C. The change in the concentration of both components and the formation of the products were investigated depending on time. The products thus formed were isobutylene, tert‐butyl alcohol, acetone, and the oxidation products of methylenebisphenol. Individual amounts produced depended on the reaction temperature and the initial concentration of the starting compounds. GPC was used for the following transformations of methyl‐enebisphenol. The decomposition of tert‐butyl hydroperoxide was found to be accelerated by the presence of methylenebisphenol, which, however, affects but little the splitting of the tert‐butoxyl radicals yielding acetone.
Antioxidants and stabilizers.XLII. Reaction of tert‐butyl hydroperoxide with mononuclear and binuclear phenols
Authors: Zikmund L. , Brodilová J. , Pospíšil J. 
Published: June 2010

AbstractThe effect of the structure of alkylphenols and methylene‐bisphenol on the course of decomposition of tert‐butyl hydro‐peroxide has been investigated. All phenols under investigation have been found to accelerate the decomposition to a varying degree. During the reaction, the phenols undergo oxidative transformation, resulting in the formation of oligomers as a methyl or ethyl group is substituted for phenols at the position para to the hydroxyl group. All types of phenols yield decomposition products which have a lower molecular weight than the initial phenol and are strongly absorbant in the UV region. Time dependences of the formation of tert‐butyl alcohol, isobutylene, and acetone have been tabulated. From the data measured, stoichiometric ratios q of the reaction of tert‐butyl peroxide with phenols and costants, expressing the rate of the loss of tert‐butyl hydroperoxide, have been calculated.
Transport of dissolved carbon dioxide through silicone rubber membranes
Authors: Hwang Sun‐Tak , Strong Gary D. 
Published: June 2010

AbstractThe transport of dissolved carbon dioxide through silicone rubber was studied as a function of concentration levels and membrane thicknesses. Investigations were made under steady‐state conditions only. A necessary provision to the determinations of permeability coefficients was the development of measuring the concentration of dissolved carbon dioxide in water. A method called “gas phase analysis” was developed. This procedure involves analysis of gas phase samples above CO2‐H2O solutions sealed in equilibrium vessels. The permeability was found to be very nearly independent of concentration level. The previously developed equation relating the reciprocals of permeability and membrane thickness was used to explain the experimental data. The importance of boundary resistance was emphasized.
Permeation of liquid water in a filled epoxy resin
Authors: Manson J. A. , Chiu E. H. 
Published: June 2010

AbstractCertain epoxy paints and filled resins were shown to be potentially useful protective coatings for concrete exposed to hot saline media. Since, however, very little information was available about water‐polymer interactions at elevated temperatures, a study of permeation and of dielectric and mechanical relaxation was begun. In this part of the study, the permeation of liquid water through an epoxy film (filled with 0, 10, and 20 wt.‐% spherical glass beads) was measured at temperatures up to 130°CC. As expected, the filler served to decrease permeation, though to a greater extent than predicted. Arrhenius plots of permeation revealed several other characteristics. In general a discontinuity was observed at Tg, with the apparent energies of activation, Ea, being lower below Tg (4–11 kcal/mole, compared to 19–26 kcal/mole). Both the sharpness of the transition and Ea were sensitive to the history of the specimen. At elevated temperatures, the most highly filled specimen showed an additional relative decrease of permeability in comparison with other specimens. An interpretation of the data is proposed, based on segmental mobility as affected by restrictions due to the presence of filler particles.
A diffusion‐solubility model for reverse osmosis
Authors: Machacek Raymond F. , Osburn James O. 
Published: June 2010

AbstractThe sorption of a dye by hollow fiber nylon reverse osmosis membranes was measured. Equations for the unsteady state reverse osmosis separation of the dye from water are solved by numerical analysis, and are shown to fit data on this process. This gives credence to the assumed model, which is that of solution of dye in the membrane followed by diffusion through it.
Radical initiated synthesis of hydroxyl terminated polymers using aqueous hydrogen peroxide as initiator
Authors: Pinazzi Christian , Legeay Gilbert , Brosse Jean‐Claude 
Published: June 2010

AbstractAqueous hydrogen peroxide thermally decomposes into two hydroxyl radicals which readily initiate a radical polymerization process. Ethylenic monomers and aqueous hydrogen peroxide are generally nonmiscible liquids in all proportions, and the addition of an alcohol to the reaction medium greatly modifies the thermodynamic conditions. Liquid and solid products are obtained having 1.7 to 1.9 hydroxyl groups per macromolecule and their average molecular weights vary between 700 to 100,000. For diene monomer polymerization, low molecular weight oligomers as well as higher molecular weight polymers are obtained. Structures of the diene polymers obtained show that aqueous hydrogen peroxide‐initiated polymerization proceeds by a 1, 2 addition for their initiation step and a 1, 4 addition for propagation.
A model for the solid state polymerization of calcium acrylate hydrates
Authors: Watine F. B. , St‐Pierre L. E. 
Published: June 2010

AbstractThe variations in the rates of polymerization of calcium acrylate hydrates as a function of composition, in vacuo and in air, are described by a three‐phase model in which only two phases undergo polymerization at any given composition. It is proposed that an “active” phase which involves the total monomer volume is present at the 0.5 H2O hydrate. This active volume concept supersedes the phase boundary model previously employed to explain the nonlinear polymerization‐composition behavior.
Contribution of water to the initiation of solid state polymerization of acrylate and methacrylate salt hydrates
Authors: Watine F. B. , St‐Pierre L. E. 
Published: June 2010

AbstractThe role of the water of crystallization in the initiation of the solid‐state polymerization of calcium acrylate and barium methacrylate hydrates has been investigated in terms of its physical and chemical involvement in the polymerization reaction. The dynamics of the water of crystallization was studied by infrared absorption on D2O hydrated salts in the presence of water vapor. The variation of the relative intensities of the OD and OH bands in the infrared spectra showed that a rapid exchange occurred between the water of crystallization and water in the atmosphere. ESR studies on D2O hydrated salts proved that radicals, produced from the water, contribute substantially to the initiation of the polymerization reaction.
On the mechanism of radiation‐induced crosslinking of poly(vinyl chloride) in the presence of some polyfunctional monomers
Authors: Sukhov F. F. , Slovokhotova N. A. 
Published: June 2010

AbstractSome features of low‐temperature radiolysis of poly (vinyl chloride) and the effect of added polyfunctional monomers such as triallyl cyanurate have been studied using the technique of infrared spectrophotometry. It has been found that the radiation yield of HCl formed in the radiolysis of poly(vinyl chloride) alone at 100°K is equal to 2.5. Additives form a complex with radiolytically produced HCl. The structure of this complex corresponds to on oxonium compound. The radiation yield of the complex reaches 50–80 per 100 eV of energy absorbed by additives. At the same time, the addition of triallyl cyanurate in poly (vinyl chloride) decreases the radiation yield of HCl associated with polymeric matrix by 2–3 times. The reaction of the allyl groups of the additive with the polymer free radicals already occurs at low temperatures. On heating, the irraditated at low temperature samples, the complex of additive with HCl decomposes, the remaining allyl groups disappear, and triazine rings are partly transformed to the isocyanurate form. These results are interpreted in terms of a mechanism which postulates the localization of the dehydrochlorination process of poly(vinyl chloride) in the vicinity of the additive molecules and the promotion of crosslinking efficiency by the formation of complex of additive with HCl.
Light activated polymerization of isobutylene by friedel‐crafts catalysts
Authors: Marek M. , Toman L. 
Published: June 2010

AbstractThe effect of light upon the course of the polymerization of isobutylene catalyzed with the Friedel‐Crafts halides and carried out at temperatures ranging from 0 to –78°C in the solution of n‐heptane was investigated. The polymerizations carried out under dry conditions in the dark at temperatures lower than –40°C in the presence of VCI4, TiCl4, TiBr4, and TiI4 as catalysts practically did not occur at all. If, however, the reaction mixture was irradiated with visible, ultraviolet, or infrared light, rapid polymerization occurred, which stopped when the light source was switched off and which was accelerated again when the light was switched on. In the case of polymerizations activated with visible light, the polymerization and conversion rates depend upon the kind and concentration of the catalyst used and on the temperature and intensity of the light source. The polymerization rate decreased in the order VCI4 > TiCl4 > TiBr4 > TiI4; in all cases it increased with decreasing temperature. No accelerating effect of the light used could be observed for polymerizations catalyzed with the AlBr3 and SnCl4 halides. The possible radical‐cationic polymerization mechanism is discussed.
Quantum theoretical calculations concerning the copolymerization behavior of vinyl monomers and restricted rotation in radicals of vinyl polymerization
Authors: Roth H.‐K. , Fleischer G. 
Published: June 2010

AbstractSome features of the addition reaction of vinyl polymerization were investigated. The factors influencing the copolymerization behavior of the monomers was found by MO calculations. The meaning of Q of the Q‐e scheme of Alfrey and Price shows the resonance stabilizations could be confirmed. The meaning of e was found in the electrostatic interaction between monomer and radical in the transition state caused by the dipole moments of monomer and radical. The radical motions, especially the rotation around the last C‐C bond, are treated. A quantum mechanical formalism describing this rotation is declared.
Effects of association of unsaturated polyesters on their reactivity in copoly‐merization with monomers
Authors: Bulatov M. A. , Spasskii S. S. , Surovtsev L. G. 
Published: June 2010

AbstractThe high reactivity of fumaric polyesters in copolymerization reactions with monomers are discussed. The monomers acting as poor solvents cause association of the polyester. Double bonds in the associate may be ordered in such a way that the resulting arrangement favors the homopolymerization reaction. Effects of these structures may display in polymerization of low molecular compounds such as benzyl methacrylate. The relation between the polymerization rate of the associated monomer and the association degree is determined.
Study of the polymerization of acrylonitrile in dimethylformamide solution in the presence of tetramethyl thiuramdisulfide
Authors: Beniska J. , Štaudner E. 
Published: June 2010

AbstractThe induced polymerization of acrylonitrile (AN) in dimenthylformamide solution in the presence of various concentrations of tetramethylthiuramdisulfide (TMTD) at temperatures of 55, 58, 60, and 63°C, was studied. It was found, that TMTD has an inhibiting effect on the polymerization. It was also shown that the products formed during the inhibition period have a retarding influence on the further course of the polymerization. The equations for the polymerization rate during and after the inhibition period were derived. The inhibition and retardation effects of TMTD on the polymerization of AN in solution can be expressed by the help of the complex constant B+ and of the empirical constant b, respectively.
Photocopolymerization of acrylonitrile with methacrylic esters in the presence of anthraquinone dyes
Authors: Nuta Violeta , Feldman D. , Simionescu Cr. I. 
Published: June 2010

AbstractPhotocopolymerization of acrylonitrile (AN) with methacrylic esters such as methyl methacrylate (MMA), butyl methacrylate (BMA), and lauryl methacrylate (LMA) using as photosensitizer the anthraquinone dye, Indanthrone Yellow 3R (1Y‐3R), was studied. The best conversions depending upon the ratio between monomers and the duration of the process was followed and the reactivities of the comonomers (the reactivity ratios and Q and e parameters) were determined. One did find a reactivity modification in proportion as the methacrylic ester chain increased.
Polymerization of vinyl chloride by organolithium compounds. II. Polymerization of vinyl chloride by organolithium complexes
Authors: Jíšová V. , Kolínský M. , Lím D. 
Published: June 2010

AbstractThe study of the polymerization of vinyl chloride by organolithium compounds was further extended to also cover polymerizations by complex catalysts containing alkyllithium together with dicyclopentadienyl titanium dichloride (Cp2TiCl2). Attention was paid to the effects of (a) the concentration of the complex and (b) the ratio at which the fundamental components were employed in the complex on conversion and molecular weight of the resulting product of polymerization.
The copolymerization of propylene and vinyl chloride with the Ziegler‐Natta catalysts: Infrared spectra and the structure of copolymers
Authors: Kissin Yu. V. , Dankovics A. 
Published: June 2010

AbstractThis work is devoted to the infrared study of the products of the copolymerization of propylene and vinyl chloride with the modified TiCl3–Et3Al catalyst.Thus, in our view the data given demonstrates two important features of the copolymerization process of propylene and vinyl chloride on the modified Ziegler‐Natta catalyst: 1. that real copolymerization takes place in the case of this monomer pair; and 2. that copolymerization procedes on the stereospecific active sites of the heterogeneous catalyst, i.e., on the same sites which are responsible for the stereoregular polymerization of olefines. Infrared study allows one to estimate the distribution of the propylene units in the copolymers. The distribution is very typical of the random copolymers obtained with the stereospecific catalysts.
Two types of recrystallization processes during annealing of stretched linear polyethylene
Authors: Hosemann R. , Loboda‐Čačković J. , Čačković H. 
Published: June 2010

AbstractLinear polyethylene (PE), warmed up to 80°C only in the shoulder of necking process, can be stretched about 10‐fold. This material was annealed at a temperature T1 for t1 minutes and investigated by a two dimensional analysis of X‐ray small‐ and wide‐angle scattering at room temperature. By annealing at T1 ≥ 110°C after some minutes, a special recrystallization takes place for a short time, where the macroscopic density γ is constant and adjacent paracrystalline domains recrystallize to larger paracrystalline domains while the g13‐tensor component of the superlattice discontinously obtains a sharper component. This indicates that in connection with the above mentioned lateral recrystallization, the folding surfaces of the adjacent domains align to stepless larger surface areas. During this process the back folding of the chains firstly becomes quite irregular. After and before this special process, where in the γ − 1/P diagram a horizontal plateau exists, γ monotonically encreases with 1/P (P = long period) Here the averaged thickness of the paracrystalline smectic‐like layers slowly increases. This can be explained partially by lateral disintegration of paracrystalline layers, which do not go through the whole bulk material. The incubation time for the begining and end of the plateau decreases with increasing T1 > 110°C. This can be explained by raising the mobility of kinks within the paracrystalline domains with raising T1. The single ultrafibrils during annealing have not lost their character consisting of pearl‐string‐like chains of paracrystallites connected to each other by tie molecules. They have only aligned to their neighbors with a higher order: they develop well defined larger inner folding surfaces and paracrystalline domains extending over several ultrafibrils.
Isothermal crystallization studies on nylon 6.6 and 6.10 by calorimetry
Authors: Savolainen A. 
Published: June 2010

AbstractThe DSC technique was used to investigate the isothermal crystallization of nylon 6.6 and nylon 6.10. It is shown that the Avrami equation in the case of the crystalline polymers is useful during the hole crystallization process. The observed differences in the activation energies of crystallization of annealed and untreated nylon 6.6 and 6.10 polymers are due to the differences in inner order in the specimen during the primary and the secondary crystallization.
Solution properties of cyclo‐ and cyclized polyisoprenes
Authors: Vohlídal J. , Boháčková V. , Matyska B. 
Published: June 2010

AbstractA series of linear 1, 2 and 3, 4 polyisoprenes were cyclized to various degrees by the action of TiCl4 and POCl3 as catalysts. Light scattering and viscometric studies of cyclized samples showed that the cyclization process was accompanied by an increase of the steric hindrance factor σ up to a certain value. At higher degrees of cyclization, on the other hand, the characteristic dimensions of the macromolecules diminished due to the internal cross‐linking.
Structural levels of supermolecular organization in aqueous solutions of poly (vinyl alcohol)
Authors: Klenin V. J. , Klenina O. V. , Kolnibolotchuk N. K. , Frenkel S. Ya. 
Published: June 2010

AbstractThe isothermal rise in supermolecular order (SMO) in aqueous solutions of poly (vinyl alcohol) (PVA) over a wide range of temperature and concentration and also under shear has been studied. SMO was characterized by the equivalent average radius of super‐molecular particles (SMP) rΛ, estimated by the turbidity spectrum τ = τ(Λ).The methods of gradient dependence of viscosity electron and polarize‐optical microscopy, and light scattering according to Debye‐Zimm have also been used.It is shown that the process of isothermal rising of SMP over a wide range of temperature and solution concentration consists of two distinct stages: a relatively rapid rise and then a slow rise of SMP.In aqueous PVA solutions SMO represents, generally, the hierarchy of some its levels. The first level is considered to be the supermolecular particles, which form after the dissolution of the whole polymer mass. The character of this level is determined by the microstructure of the sample in the condensed state and dissolution conditions. The particles of the first level are the heterogeneous formation nuclei of the second level–particles of the fibril type. Fibrils, which have risen from the solution at high temperature (T ≥ 80°C) have shown the ability to aggregate into anisodiametric structures as the solution cools. These aggregates, determined to be the third level, are very sensitive to temperature. In turbulent shear the rising rate of SMO increases greatly as the characteristic concentration is made smaller.The results obtained give us reason to conclude that the rise in SMO in aqueous PVA solutions is due to the crystallization of macromolecules when the low molecular weight component is available.