bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antioxidants and stabilizers. XLIV. Properties of halogenated dihydric phenols
Authors: Lerchová J. , Obali M. , Kotulak L. , Pospíšil J. 
Published: June 2010

AbstractThe effect of halogenated and alkylated dihydric phenols on the autoxidation process of tetralin and cumene initiated at 65°C with AIBN has been investigated. The character of substitution effects the antioxidative activity of the derivatives of the pyrocatechol and hydroquinone series in a different way. All halogenated pyrocatechols were less active than unsubstituted pyrocatechol. Their antioxidative activity increased in both substrates proportionally to the number of the halogen atoms. On the other hand the introduction of chlorine atoms into the hydroquinone ring led to a considerable increase in the antioxidative activity compared to hydroquinone and to its alkyl derivatives. In both substrates isomeric dihydric phenols exhibited different retardation of the oxidation course in the step following the induction period. The reasons for the different behavior are discussed.
Pressure‐induced diffusion in swollen butyl rubber membranes
Authors: Paul D. R. , Carranza D. H. 
Published: June 2010

AbstractMembranes were prepared from butyl rubber of different levels of chain unsaturation to produce membranes with four different well characterized cross‐link densities. Pressure‐induced permeation rates through them were measured for various organic liquids which highly swell the membranes. The data conformed to and were analyzed by previously published theories. It was found that the product of the diffusivity of the liquid in the membrane and the pure liquid viscosity is very nearly a constant which is approximately 20% less than observed earlier for polyisoprene membranes. More lightly cross‐linked membranes yielded higher liquid fluxes at fixed pressures. Most of the effect is attributed to the higher degree of swelling of these membranes. The diffusion coefficient is essentially independent of crosslink density over the range studied.
Effect of monomer‐active filler system structurization on thin layer polymerization
Authors: Morozova E. M. , Yeliseyeva V. I. , Travnikova L. A. 
Published: June 2010

AbstractThe polymerization of monomers in a thin layer in air is very sensitive to the variations in the initial composition of the polymerized system. A study of the effect of initial mixture composition on the regularities of the polymerization kinetics elucidates the specific features of the process, and thereby facilitates its control. This paper reports the effect of active fillers (aerosil) on the kinetics of bulk polymerization of aminoalkylmethacrylates in a layer of specific thickness and in volume. The rheological parameters of the polymerized system were measured. Such investigations revealing the kinetics of the variations in the rheological parameters during polymerization are of considerable significance for establishing a relationship between both processes. Besides, they have practical value for the production technology of polymer coatings by direct polymerization of monomers. The data obtained in this work clearly demonstrate the effect of coagulation structure developed by adding an active filler into system to be polymerized on the polymerization process.
Anionic copolymerization of acrolein with aldehydes. III
Authors: Lapena A. , Mateo J. L. , Sastre R. 
Published: June 2010

AbstractUnsaturated polyacetals have been prepared by anionic copolymerization of acrolein with aldehydes, such as, acetaldehyde, propionaldehyde, isobutylaldehyde, pivaldehyde, and benzaldehyde. The new copolymers have essentially an acetal structure as the result of the acrolein preference to copolymerize through the carbonyl group when alcaline cyanides are used as catalysts. The influence of temperature, nature of the aldehyde and monomer composition on the molecular size, polymerization rate, and composition and structure of the copolymer are studied. These copolymers undergo cross‐linking when exposed simultaneously to oxygen and light. The variables affecting the oxidation process and the products obtained were studied.
Anionic polymerization of caprolactam. XLV. Decay and regeneration of catalytic activity in anionic polycaprolactam via 3‐oxoamides
Authors: Bukač Z. , Šebenda J. 
Published: June 2010

AbstractN, 2‐Diethyl‐3‐oxohexaneamide was chosen as a model compound for the investigation of transformations of the 3‐oxoamide structures in anionic polycaprolactam. Dipropyl ketone, ethyl butyramide, N,N′,2‐triethyl malonamide, 1,3,5‐triethyl‐6‐propylpyrimidine‐2,4‐dione are formed under the conditions of anionic polymerization, along with carbon dioxide and traces of ethyl isocyanate, ethyl amine, and N,N′‐diethylurea. The formation of these compounds can be explained by the cleavage or rearrangement of the 3‐oxoamide N‐anion and by secondary reactions of isocyanate with the initial 3‐oxoamide. Some of the reactions of the 3‐oxoamide give rise to growth centers as well as a strong base, thus causing regeneration of the catalytic activity. However, one part of the activity vanishes irreversibly, owing to the formation of stable acid products.
Suggested interpretation for the anomalous kinetics of acrylonitrile polymerization in homogeneous solution
Authors: Patron L. , Mazzolini C. , Moretti A. 
Published: June 2010

AbstractThe polymerization in homogeneous solution of acrylonitrile shows an anomalous kinetic behavior. The reaction order in respect to the monomer appears higher than 1, and approaches the order of 2 at low acrylonitrile concentrations (< 2M). This behavior was given various interpretations. No completely satisfactory explanation is, however, available. By taking into account some secondary radical reactions recently discovered (polymerization through CN), a new interpretation of the kinetic anomalous behavior is suggested, and a kinetic model is given which also takes into account the propagation through the triple CN bond.The equations so fully derived justify the experimental results. A reaction order of 2 in respect to the monomer for (AN) tending to zero, and approaching 1 for (AN) > 2M, is deduced from the assumptions made. According to the proposed mechanism, the kinetic deviations from theory do not depend on the initiation rate, as confirmed by experimental results, but only on monomer concentration.
Charge transfer complexes of maleic anhydride in radical homo‐ and copolymerization
Authors: Rzaev Z. M. , Bryksina L. V. , Sadykh‐Zade S. I. 
Published: June 2010

AbstractRadical copolymerization of maleic anhydride (MA) with a number of electron‐donor monomers has been investigated. Charge transfer complexes (CTC) of MA with vinyltriethoxysilane (VTES), vinylcyclohexylcetone (VCHC), and styrene (St) have been fixed. On the basis of NMR and ultraviolet spectroscopy data, the equilibria constants of complexation (K)1 and extinction coefficient (ε) for various pairs of donor‐accepting monomers have been determined. The terpolymerization has been carried out involving the mentioned monomeric CTC (complexomer). Copolymerization constants r2 and r2), specific activity (Q), and polarity (e) factors for monomer and complexomer pairs, constituting the systems: MA‐St‐VTES, MA‐St‐NCH, and MA‐St‐VCHC have been determined. Some regularities of terpolymerization with MA complexomers present have been revealed. It has been shown that the three‐component system polymerizes at the stage two‐component polymerization of either complexomer MA‐St with VTES (or NCH) or two complexomers MA‐St with MA‐VTES (or MA‐NCH).
Influence of orientation on the relaxation and ultimate properties of polypropylene
Authors: Retting Wolfgang 
Published: June 2010

AbstractAs is known, the relaxation maxima of polymers are often shifted within the time or temperature scale if the materials are stretched or drawn. This behavior is due to changes of the free volume and/or of the crystallization and orientation of the stretched specimens. Since the relations between these parameters and the shift of the maxima are not yet known very well, an examination was made using polypropylene as a suitable example. The knowledge of these relations is of technical importance, too, because the shift of the maxima is often accompaned by a shift of corresponding brittle‐tough transitions.The relaxation maxima were determined in a good approximation by measuring the time‐dependent moduli of elasticity and by differentiating the modulus curves. It was found that the main maximum of polypropylene shifts with increasing draw ratio to longer times. At the same time the activation energy of the maximum decreases. Tensile tests, carried out on the unstretched and on the stretched specimens, yielded the same shift of the brittle‐tough transition as that of the main maximum. The molecular causes of this behavior are discussed.
Conductivity of two semiconducting poly‐2, 4‐diamino compounds
Authors: Löfgren B. , Virtanen J. 
Published: June 2010

AbstractThe electrical conductivity of poly‐2, 4‐diaminoanisole is compared with the conductivity of poly‐2, 4‐diaminotoluene in the temperature range 293–450°K. The conductivity obeys the exponential law σ = σ0 exp {−Ea/kT} for both polymers, Poly‐2,4‐diaminoanisole conducts better than poly‐2, 4‐diaminotoluene, and the σ0 value for poly‐2, 4‐diaminoanisole is one decade higher than for poly‐2,4‐diaminotoluene, while the activation energies are equal at equivalent molecular weights.
A study of short‐range order in amorphous polymers by diffraction methods
Authors: Markova G. S. , Ovchinnikov Ju. K. , Bokhyan E. B. 
Published: June 2010

AbstractThe structure of amorphous polymers and polymer melts differing in chemical composition and molecular configuration have been studied by means of electron and x‐ray diffraction methods. The final result of the investigation are differential radial distribution curves (DRD), which correspond to fluctuations of the potential (electron diffraction method) or to fluctuations of electron density (x‐ray diffraction method). It was found that for all investigated systems on the DRD‐curves, from two to three intermolecular peaks have been obtained. The appearance of such a number of intermolecular maxima on the DRD curves for strongly asymmetrical molecules was explained only by the parallel packing of the chain molecules. The ordered areas have been established over a wide temperature range. The sizes of these ordered areas have been estimated.
Swelling equation for gaussian networks. Networks formed by random crosslinking of primary chains
Authors: Dušek K. 
Published: June 2010

AbstractThe expression for the chemical potential of the solvent in a swollen extracted net‐work, obtained by the quasi‐chemical equilibrium treatment of crosslinked polymer solutions, has been transformed into the form of Flory's swelling equation Δμs/RT = In φs + φg + χφg2 + veg (Vs/Vp) (φφ – Bφg), where μs is the chemical potential of the solvent, φs and φg are the volume fractions of the solvent and polymer in the gel, respectively, φ is the value of φg at network formation, χ is the polymer‐solvent interaction parameter, φs and φp are partial molar volumes of the solvent and polymer segment, respectively, and veg is the number of elastically active network chains per polymer segment. For random crosslinking of primary chains, B = 1 – (vg – 2/rng)/2veg (vg is the fraction of crosslinked segments in the gel and rng is the number average degree of polymerization of primary chains bound to the gel). The parameter B is independent of the coordination number of the lattice and varies from 2/3 at the gel point to 1/2 for networks formed of infinitely long primary chains. The interaction parameter χ is a complex function of the interaction free energy, lattice coordination number, and network parameters, and usually increases with increasing degree of crosslinking. Possible variations of B and χ are demonstrated for a number of primary chain distributions. The network parameters have been calculated by using the theory of cascade processes.
Relationship between rheological behavior of solutions and composition of acrylamide and acrylic acid copolymers
Authors: Jaćović Mihailo S. , Rajić Živojin 
Published: June 2010

AbstractThe rheological behavior of aqueous solutions of ten acrylic acid and acrylamide copolymers was studied. The mole fraction of acrylic acid in the copolymer ranged from 0.042 to 0.443. Fifteen aqueous solutions for each copolymer were prepared by including all combinations for five values of the degree of neutralization and for three solution concentrations. All other parameters being constant, solution viscosity increases with the degree of neutralization of carboxylic groups in a copolymer. We introduced the expression (ηn –/(η0n), where ηn and η0 are the viscosities of solution at the degree of neutralization n and 0, respectively, and called it the neutralization viscosity number. It has been found that the limiting neutralization viscosity number for n = 0 is a linear function of the acrylic acid mole fraction in the copolymer with acrylamide and that it is independent of the copolymer molecular weight and solution concentration.
Some new ideas in liquid state physics and their impact on polymer science
Authors: Gaeta F. S. 
Published: June 2010

AbstractThermal agitation in liquids consists of high‐frequency elastic waves. Thermal conductivity being a measure of how easily these waves drift down a gradient of temperature can be expressed as a function of the speed of sound in the liquid. The proposed expression agrees with experimental results.More important is the consideration that energy propagating in the form of waves entails propagation of mechanical momentum, the flux of momentum being equal to the flux of energy divided by the velocity of wave propagation. This momentum transported by the waves can be transferred to the bulk of the liquid, thereby contributing to viscosity.Another consequency of the propagation of momentum connected with thermal waves is that whenever heat flows within a solution, radiation pressures are developed, which make the disperse particles migrate along the temperature gradient. This is the physical explanation of thermal diffusion. The analytical expressions which are derived allow us to develop a new method of characterization of polymers and of macromolecules of biological origin. Furthermore, the measurable forces produced by the flow of heat on macroscopic blocks of polymeric materials, suspended by appropriate means within a liquid, show a dependence on the state of the polymeric material and on its thermal and mechanical history.
Some properties of copolymers containing phosphoryl groups
Authors: Kosolapoff G. M. , Voris F. S. 
Published: June 2010

AbstractCopolymers were prepared from tertiary phosphine oxides containing a vinyl group, on the one hand, and esters of vinyl‐ and p‐vinylphenylphosphonic acids, the hydrolysis of which afforded a series of copolymers containing a polyvinyl chain with side chains of R2P(O) and (HO)2P(O) types. The interaction between these afforded considerable variability of viscosity of solutions of such substances in media with various pH values.
Synthesis and thermal stability of poly‐n‐α‐naphthylmaleimides
Authors: Barrales‐Rienda J. M. , Gonzalez Ramos J. 
Published: June 2010

AbstractTwo samples of poly‐N‐a‐naphthylmaleimide (PNNMI) prepared by free radical polymerization under different experimental conditions have been characterized. The elemental analysis of both samples indicates the same chemical composition, although they are different from a structural point of view. Their structures have been established by spectroscopic methods.Rates of thermal degradation for both PNNMI samples have been analyzed by programmed thermogravimetry using a multiple‐heating‐rate procedure. Overall activation energy and order of reaction have been calculated. Values of 40 and 24 kcal/mole for the overall activation energy and a value close to unity (1.2 and 0.8) for the order of reaction for both polymers have been found.
Degree of polymerization and polydis‐persity of native cellulose
Authors: Holt C. , Mackie W. , Sellen D. B. 
Published: June 2010

AbstractCellulose trinitrate was prepared from cotton (Deltlapine) under a variety of conditions and investigated in solution using the techniques of light scattering, osmotic pressure, viscometry, and gel permeation chromatography. Gel particles associated with incompletely nitrated material were shown to be present in the more mildly nitrated samples and calculations were made to find the true weight‐average molecular weight of the coil component. As the nitration time increased, the measured degree of polymerization fell, and due to lower solution viscosities removal of gel particles by centrifugation became easier. It was possible to show that samples obtained by nitration for times in the range of 2 to 25 hr at 20°C had a low degree of polydispersity with DPw/DPn in the range 1.3 to 1.5. Assuming this also to be the case for the more mildly nitrated samples, extrapolation back to zero time of nitration, assuming a random degradation process, suggests a virtually monodisperse starting material with a degree of polymerization of about 8000. However, it is possible that molecules of this size result from some morphological feature of the cell wall and do not represent the true length of the cellulose chains.
Grafting of acrylonitrile on cellulose xanthate
Authors: Ehrnrooth Elsa 
Published: June 2010

AbstractA study has been made of the grafting of acrylonitrile onto a bleached kraft pulp by application of the xanthate method developed by Faessinger and Conte. Acrylonitrile was grafted to the cellulose in aqueous suspension at 25°C, with cellulose xanthates of gamma numbers from 3 to 13. The reaction system contained 1–2 percent xanthogenated pulp, 0.2–0.9 mole/1. hydrogen peroxide, 0.45–1.0 mole/1. acrylonitrile, and the reaction time was 45 min. In some cases 0.6–60 mmole/1. sulfuric acid was added to the reaction system. The grafting yield was calculated from the nitrogen content of the grafts. The degree of polymerization (DP) of the grafted polyacrylonitrile, after hydrolytic removal of the cellulose, was calculated from the limiting viscosity number of dimethylformamide solutions of the polymer at 25°C, and use of the formula [ε] = 2.43 × 10−4 (M)0.75. The grafts were found to contain 10–35 percent polymer of DP = 350–1000, and an average number of 1–4 grafted polymer chains per cellulose chain, i.e., less than 5 percent of the number of xanthate groups initially present in the cellulose xanthate. The number of grafted polymer chains was dependent upon the pH, and the DP of the grafted polymer was dependent upon the monomer and xanthate concentrations; the higher the monomer concentration was, and the lower the xanthate concentration was, the higher it became. Possible mechanisms for grafting are discussed.
Polymerization and copolymerization of vinyl phosphonic (acid) diethylamide and vinyl pyrrolidone
Authors: Usmanov Kh. U. , Nazhmiddinov Sh. , Nurmukhamedov Sh. 
Published: June 2010

AbstractSynthesis of phosphoramide high molecular weight analogs presents interest polymerization of vinyl phosphonic (acid) diethylamine and its copolymerization with vinyl pyrrolidone are suggested for discussion.
High‐speed thin‐foil calorimetry
Authors: Hager Nathaniel E. 
Published: June 2010

AbstractA method is described for performing adiabatic scanning calorimetry on thin samples heated at high speeds. Sample sheets are inserted between layers of a folded metal foil heater to form a stacked array. A thin‐foil thermocouple is inserted near the median plane of the array. The sample assembly is heated by passing a current through the foil heater. There is a brief initial period during which the sample interior heats adiabatically. During this period, the thermocouple signal is traced as a function of time on a chart recorder.Analysis of the chart yields the sample heating rate dT̃/dt at selected values of the mean sample temperature T. Specific heat values are calculated from dT̃/dt, using an energy‐conservation equation. The sample thickness is kept small to permit attaining rapid heating rates without excessive temperature gradients. The overall thickness of the stacked array is designed to make the adiabatic period sufficient in duration, so that results are valid over the desired temperature range.Results are shown for polytetrafluoroethylene and polyethylene terephthalate at various heating rates up to 600 K/sec. At low speeds, results agree with previously published data, but at higher speeds radically different curves are obtained. Above the glass transition temperature of the polyethylene terephthalate, it is observed that the positions of inflections in the specific heat curve vary sharply with sample heating speed.
Thermo‐optical analyses of poly(2‐methyl‐6‐benzyl‐1,4‐phenylene oxide)‐poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends
Authors: Shultz A. R. , Gendron B. M. 
Published: June 2010

AbstractBlends of poly(2‐methyl‐6‐benzyl‐1,4‐phenylene oxide) (PMBPO) with poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO® resin) form clear, transparent films. Thermo‐optical analyses of solvent‐cast and compression‐molded films comprising PMBPO‐PPO resin mixtures at 0.1 weight fraction composition intervals over the complete composition range prove these blends to be homogeneous. True thermodynamic compatibility of the polymers is thus indicated. The thermo‐optical transition temperatures, TTOA, defined as the temperatures at which birefringence disappears in scratches on the films during 10°/min heating, are found to increase monotonically with increasing PPO resin weight fraction w2, in the manner: TTOA (°C) = 120 + 101 w2. Differential scanning calorimetry on the pressed films also indicates polymer compatibility yielding single glass transition temperatures Tg (DSC) increasing monotonically from 99°C for the PMBPO to 209°C for the PPO resin.
Interfacial morphology and mechanical hysteresis in S‐B‐S triblock copolymers
Authors: Kaelble D. H. , Cirlin E. H. 
Published: June 2010

AbstractSignificant aspects of the interfacial phase continuity and mechanical stress‐strain hysteresis in S‐B‐S triblock copolymers, where S is polystyrene and B is polybutadiene, are analyzed in terms of a cavitation model for interfacial debonding. Extension‐recovery data in tensile deformation at temperatures from −120°C to 90°C include the glass temperatures of both the S and B phases. The correlation of rheological response at low deformation ϵ = ΔL/LO ⩽ 0.02, where the interfacial phase is intact, with high deformation response ϵ ⩾ 1.0, where interfacial debonding is substantially complete, isolates the strain‐time‐temperature function B(t,ϵ) which defines the interfacial continuity. Analysis of this function by use of the Halpin‐Polley model for kinetics of micro defect growth isolates an intial cavity nucleation process and subsequent propagation and coalescence of cavities at distinct levels of B(t,ϵ). At temperatures above 20°C the work lost WL due to mechanical hysteresis in stress‐strain response is correlated directly with the interfacial work of adhesion Wa between S and B phases of Kraton 101 by means of the model for interfacial morphology.