bluuebunny/crossref_metadata_2025 huggingface dataset:
A comment on non‐uniform expansion of a coiled polymer
Authors: Chikahisa Yoshiaki , Tanaka Tsuruyo
Published: June 2010

In many approximate theories of the excluded volume effect a coiled polymer chain is assumed to expand uniformly as the solvent power is increased. The failure of this assumption is demonstrated explicitly for the first‐order (single contact) perturbation; i.e., for ∣z∣>>1, where z is the usual excluded‐volume parameter. It is shown that parts of a chain near the ends suffer less expansion than the regions near the middle.
Reinforcement in rubber‐modified polystyrene
Authors: Schmitt J. A.
Published: June 2010

It has been proposed recently that polystrene is reinforced by rubber because the energy of an impact is dissipated by separation of rubber particles from polystyrene with the formation of many associated micro‐cracks and/or crazes in the polystyrene, starting at the separations. A necessary condition is that the rubber is in a state of triaxial tension which result from its higher rate of contraction compared to that of polystyrene. Further evidence is presented to support this mechanism. The higher rate of contraction of rubber compared to other polymers is demonstrated visually by embedding pieces of rubber in epoxy resin and curing at various temperatures. Holes develop in the rubber on coolling. Triaxial tension can develop only when the rubber is sufficiently cross‐linked and when there is good adhesion to the matrix polymer, otherwise, the rubber particle will either separate at the interface or develop a hole. This is demonstrated by embedding radiation cross‐linked rubber in epoxy and also by milling such rubbers into polystyrene. This mechanism explains the failure of other types of fillers to reinforce polystyrene. The optimum rubber particle size is also closely related. A polystyrene‐rubber system is described to which fillers were added to modify the triaxial tension and thus affect the impact strength.
Molecular motions in some polycarbonates
Authors: Garfield Lawrence J.
Published: June 2010

Molecular motions in the bulk polycarbonates of bis(4‐hydroxyphenyl)‐2,2‐propane, bis(4‐hydroxyphenyl)hexafluoro‐2,2‐propane, and bis(4‐hydroxyphenyl)1,3‐dichloro, tetrafluoro‐2,2‐propane have been studied by wide‐line nuclear magnetic resonance techniques. Magnetic resonance information obtained over a broad temperature range from both H1 and F19 nuclei has been used to assign various mobility phenomena to specific segments of the macromolecules. Furthermore, because of the close similarity in size of the fluorine and hydrogen atoms, F19 resonance information yields some further insights on molecular motions in BPA polycarbonate. The rotation of ‐CF3 groups, which begins at 283°K, is apparently cooperative with the motion of the adjacent phenyl groups. The effect of the ‐CF3 groups on the restricted motion of the adjacent phenyl groups is the same as that of ‐CH3 groups. Furthermore, it is inferred that in BPA polycarbonates the restricted motion of the phenyl groups occurs cooperatively with the carbonyl group and that this mode of motion is the principal contributor to the dielectric and mechanical loss peaks observed near 170°K. The glass transition temperature of the dichlorotetrafluoro compound is only 5°C higher than the hexafluoro compound. Nevertheless, the reorientation of the ‐CF2CL groups and the phenyl groups in the dichlorotetrafluoro compound occurs 100°C higher than the corresponding motions in the hexafluoro compound.
Hemical and spectral sensitization of the photoconductivity and the photo‐E.M.F. In polymeric acetylenides
Authors: Mylnikov V.
Published: June 2010

The marked change of the conductivity, the photoconductivity and the photo‐e.m.f. is revealed when the poly‐copperphenyl acetylenide (PAC) is treated by DNA, RNA and adenine. The spectral characteristics of the photoeffect, the sign of the charge carrier and kinetics of the photoconductivity are studied. The data obtained is explained by the creation of the new recombination centers after treatment of the PAC. The treatment of the polymer by amino acids leads to creating the complex copper (II) compounds and aminoacid residue. It is shown that the inner photoeffect in PAC can be spectrally sensitized up to the near infra‐red region after the dye adsorption on the polymer surface. The energy transfer mechanism is preferred for the explanation of the I.R. sensitization.
Thermodynamics and the equilibrium state of a binary copolymer that is determined by next‐nearest neighbor intrachain effects
Authors: Theil Michael H.
Published: June 2010

The equilibrium state of an infinite molecular weight, binary copolymer which is determined by next‐nearest neighbor placements of its counits is defined in terms of the conditional probabilities describing such placements and the standard state free energies governing them. The combinatorial method is used to derive the entropy of sequence length distribution, ΔSD. When ΔSD is combined with an expression for the energy of reaction which employs the standard‐state free energies of triad formation an expression for the copolymer's free energy is obtained. Since enumeration of the interrelationships among the possible triplets reveal three independent conditional probabilities, separate differentiations with respect to each of three conditional probabilities are equated to zero in defining the equilibrium state. These equations reduce to the more special case previously derived when only nearest‐neighbor effects are considered.
Interaction of cellulose with organic liquids and vapors
Authors: Colombo Edward A. , Immergut E. H.
Published: June 2010

The interaction of three organic compounds (benzene, methanol, and N, N′‐dimethylformamide) with cellulose was examined, and an attempt was made to relate the extent of interaction with cellulose structure and the molecular structure of the organic compound. The observed interaction between cellulose and benzene, methanol, and DMF is consistent with the idea that the extent of interaction is a function of size and hydrogen‐bonding ability of the swelling liquid. The surface areas, obtained from the vapor isotherms, indicate that the interaction is in the order benzene < methanol ≈︁ DMF. Heats of adsorption determined for the three vapors on cellulose are in good agreement with literature values obtained from calorimetric heats of wetting and, when compared with heats of hydrogen‐bond formation for model systems, indicate that the interaction must involve hydrogen‐bond formation. The heats of adsorption indicate that in the case of methanol and DMF the hydrogen‐bond formation extends over a wide range of vapor coverage, while for benzene vapor the hydrogen‐bond formation falls off rapidly after completion of a monolayer. Limited swelling measurements indicate that the heat of adsorption may be more important than the size of the swelling liquid molecule in the early stages of swelling, but after all the high‐energy sites in the cellulose (attributed to mechanical strains induced in the fiber on drying or processing) become saturated, the size of the molecule becomes more important in determining the extent of swelling.
Post‐polymerization of methyl methacrylate after electroinitiation at the anode
Authors: Palit Santi R.
Published: June 2010

It has been found that aqueous solutions of methyl methacrylate (MMA) containing sodium acetate when electrolyzed between platinum electrodes in an almost closed large test tube go on yielding the polymer for a long time, extending over a couple of days even after the current is switched off. MMA (ca. 1% v/v) and sodium acetate (0.2–0.6N) give good yield of polymer. In a typical experiment, when a 1% MMA solution in 0.3N sodium acetate is electrolyzed for about 2 hr with a current of about 100 mA, a yield in the range of 5% is obtained; however, if the system is left undisturbed after switching off the current, the almost clear solution grows turbid due to postpolymerization and after 24 hr gives a polymer yield of about 60–70%. The intrinsic viscosity of the polymer samples in benzene ranges from 1.6 to 3.7 Long‐lived free radicals not visible to the naked eye are presumably formed whose nature is yet to be elucidated.
Synthesis and properties of some phosphorus‐aziridinyl compounds
Authors: Bergmann Ernst D. , Goldschmidt Zeev , Migron Joëlith , Dancona Josef
Published: June 2010

Phosphorus‐aziridinyl compounds, which may be good crosslinking agents for biological as well as chemical‐technical systems, have been synthesized by the reaction of phosphorus oxychloride (or the corresponding thio‐compound) with diols and diamines and treatment of the resulting products with aziridine.

The chemical reactivity of the tetra‐aziridides so obtained, their infrared and their nuclear magnetic resonance spectra have been studied.
Radical and ionic polymerization of vinyl chloride with tert‐butylmagnesium chloride
Authors: Guyot Alain , Mordini Jacques
Published: June 2010

The earlier results concerning the kinetics of polymerization and initiator consumption, molecular weight distribution, and the nature of the chain ends in the polymerization of vinyl chloride initiated by tert‐butylmagnesium chloride (tBuMgCl) in tetrahydrofuran and other solvents are rediscussed in terms of the simultaneous participation of an ionic mechanism and a radical mechanism. The former is operative mainly at the beginning of the process and gives very low molecular weight products. The latter is responsible for the formation of the high polymer. The radicals are generated from the organomagnesium compound giving a tert‐butyl group as a chain end for every macromolecule. New experiments support the radical mechanism: comparison with radical polymerizations in the same conditions of temperature and solvent medium, inhibition by NO, copolymerization with vinylidene chloride. Also the high polymer is not obtained if the ionic mechanism is exalted by introduction of a powerful solvating agent, the dimethoxyethane.
Creep of plasticized poly(vinyl chloride)
Authors: Pedersen H. Leth
Published: June 2010

Test rings 0.8 mm thick are loaded about 125 N/cm2 and the creep is measured for 100–200 minutes. The load may be varied from 75–200 N/cm2.

Increase of length (δ) is plotted versus log time which gives a linear relation. δ is converted to elongation [ε = (δ × 100)/1o], and the slope of this line α = Δε/(Δ log time) gives further a linear relationship plotted versus temperature or 1000/T, the energy of activation being 5–7 kcal.

The creep is measured in the temperature interval 20–100°C where the increase of log α is between 0.01–0.015/°C. We have tested variation of plasticizers content from 30–80 parts per 100 part resin and resins having MW from 75,000–150,000. The MW was determined by means of gel permeation chromatography (Waters Associates).

Together with α the elongation after creep of one minute represents another rate parameter, the logarithm of which is linear versus temperature.

In the case where log α exceeds 1.8–i.e., an increase of 63% elongation per decade of time–the sample will break after varying times depending upon amount of plasticizer and Mw.

The method covers a wide range of creep and new plasticizers and resins may be characterised by the position of the log α/temperature‐line.
Etude de L' ionisation de films insolubles de poly‐peptides
Authors: Caspers J. , Ruysschaert J. M. , Jaffé Et J.
Published: June 2010

Recently, evidence has been obtained that the monolayers of a number of synthetic polypeptides are in the α‐helical conformation at the air‐water interface. This hypothesis has been based on measurements of deuterium exchange rates and examination of collapsed films by infrared spectroscopy.

In this paper, the influence of the interface is studied with a method of the surface chemistry: the surface potential. The modification of the properties of the ionized groups with the macromolecular conformation was more particulary investigated in the case of poly‐L‐glutamic acid. Orientation of the molecules in the monolayers is imposed by the nature of the interface (air‐water, cyclohexane‐water). The theories of the ionic double layer (Gouy model, Donnan equilibrium) allow to calculate α, the degree of ionization of the film. The results obtained demonstrate that, at the cyclohexane‐water interface, the accessibility to the ionized groups is more difficult than at the air‐water interface. The variation of α with the PH of the substrate is used to calculate an intrinsic dissociation constant K of the monomer of the spread molecules. The values are similar to that obtained in solution.
Measurement of the strength of steric barriers in non‐aqueous polymer dispersions
Authors: Doroszkowski A. , Lambourne R.
Published: June 2010

The forces of repulsion generated in the steric barriers of a series of monodisperse spherical polymer particles, varying in diameter, have been measured using a surface balance. The particles were stabilized using a graft copolymer with a poly(methyl methacrylate) backbone and heptane soluble poly(12 hydroxy stearic acid) side chains. It was established that the particles were supported on a water surface and that the stabilizing polymer was in a heptane phase in the plane of compression. From pressure‐area measurements, a stabilizing barrier thickness of 130 Å (independent of particle size) was found which was in good agreement with the value from viscometry. Compression of the particles at the interface permitted the measurement of the collapse pressure of the steric barrier from which the work done in compressing the barrier was computed. Two theoretical models for the system, one similar to Fischer's treatment of osmotic pressure changes associated with the overlap, or inter‐penetration, of the steric barrier and another based upon Ottewill and Walker's treatment of the free energy of dilution of the steric barrier have been evaluated. Both models are in good agreement with the experimental data.
The viscoelastic properties of poly(phenylene ethers). I. Unsubstituted and methyl or phenyl substituted polymers
Authors: Eisenberg A. , Cayrol B.
Published: June 2010

A series of poly (phenylene ethers) with methy or phenyl substituents or without substituents have been studied. They are: M2PPO poly (2,6‐dimethyl p‐phenylene oxide), ϕ2PPO poly (2,6‐diphenyl p‐phenylene oxide), MϕPPO poly (2‐methyl, 6‐phenyl p‐phenylene oxide), H2PPO poly (p‐phenylene oxide), and H2PPS poly (p‐phenylene sulfide).

Several sub Tg relaxation regions have been found for these polymers which seem to have a common mechanistic origin. The β region which was found for H2PPO (H2PPS), M2PPO, and ϕ2PPO has an activation energy, respectively, of ca. 12, 16, and 23 kcal/mole and is most probably due to hindered oscillatory motions of the backbone phenylene groups. The tan δ peaks at 1 cps occur, respectively, at ca. −110°, −50°, and +80°C. The next lower or γ region was found for MϕPPO and ϕ2PPO with an activation energy of ca. 12 kcal/mole and is probably due to hindered torsional oscillations of the side chain phenyl. A still lower relaxation region (called δ) was also found for the two last compounds. Its activation energy is ca. 4 kcal/mole and is most probably caused by some type of wagging motions of the side chain phenyl.

No main chain relaxation was found for MϕPPO. All the relaxations have a very low intensity. The trend in the activation energies for the β region suggests that the barrier is intermolecular. An attempt to correlate the frequencies and activation energies of the β relaxations within the formalism of O'Reilly and Tsang gave good quantitative agreement.
Applications of gel permeation chromatography in the pulping process
Authors: Alexander W. J. , Muller Thomas E.
Published: June 2010

The major changes which occur in the DP distribution of cellulose in wood pulp owing to the refining of unbleached stocks to produce several types of finished pulp have been examined by GPC. Represented in this study are sulfite and sulfate pulping processes and paper and dissolving grade pulps. Factors which influence the definition by GPC of small differences in chain length among high DP pulps were considered. The high DP extremes of ten celluloses were compared by GPC after prefractionation by fractional precipitation. Results classify only small percentages above 3500 DP and then only in the highest average DP pulps examined. The cold alkali‐soluble fractions isolated from a high and low DP sulfite paper pulp and a prehydrolyzed sulfate pulp were compared by GPC and differences have been revealed which were not evident from viscometric DP measurements.
Light scattering by cellulose. V. Anisotropy scattering by wood fibers
Authors: Muggli Reto , Marton R. , Sarko A.
Published: June 2010

Solid state light scattering patterns from single wood fibers were recorded using a laser as the light source. The scattering was recorded in the Hv mode; i.e., with the incident light beam vertically polarized, the scattered light was passed through a horizontal analyzer, thus permitting the recording of only the scattering arising from anisotropy fluctuations. The scattering pattern was confined to a narrow line consisting of regularly spaced maxima and minima. The overall scattering envelope could be accounted for by a hollow cylindrical model with helically wound dipoles, while the periodicity in the intensity is a function of fiber diameter and cell wall thickness. Comparison of relative intensities led to the conclusions that cellulose of the wood fiber behaves optically as a biaxial crystal in that the cellulose crystallites are biaxially oriented in an axial‐tangentoplanar fashion in the cell wall.
Plasticizing wood with ammonia‐control of color change
Authors: Schuerch C. , Davidson R. W.
Published: June 2010

Recent studies of plasticizing wood with anhydrous ammonia have demonstrated that pronounced changes in the color of wood can occur. These changes are thought to be the result of various oxidation and condensation reactions that are enhanced by ammonia. It was postulated that pretreatment of the wood with sulfur dioxide would effectively block these reactions and thus lead to little, or no, color change in subsequent ammonia treat‐ment. A series of tests were run on maple, birch, red oak, and douglas fir specimens that confirm this hypothesis. Reflectance spectra over the range of visible wave lengths show that both liquid ammonia at −35°C and gaseous ammonia at +25°C darken the wood with more darkening occurring at the higher temperature. Pretreatment with sulfur dioxide followed by gaseous ammonia treatment to a highly plastic state results in only slight changes in color while the reverse procedure (NH3 first followed by SO2) results in considerable color change.
Southern pineprehydrolyzates: Characterization of polysaccharides and lignin fragments
Authors: Sears K. D. , Beelik A. , Casebier R. L. , Engen R. J. , Hamilton J. K. , Hergert H. L.
Published: June 2010

Prehydrolyzates obtained by treatment of southern pine chips at 175° with steam and water were examined in parallet studies. Carbohydrates were separated from other solids and fractionated into monosaccharides, low‐molecular weight polysaccharides and highmolecular weight polysaccharides. The latter fractions were selectively subfractionated into series of glucomannans and galactoglucomannans using barium precipitation. The poly‐saccharide fractions were characterized by gel permeation chromatography (gpc), the hemicellulose subfractions by periodate oxidation, vapor pressure osmometry, polarimetry, and end‐group assay. Sugar ratios were determined on hydrolyzates of all fractions. Water prehydrolysis was shown to remove substantially more carbohydrates from the chips than steam prehydrolysis, 9.3% versus 3.3% (O.D. wood basis), and these carbohydrates had higher average molecular weight, contained more mannose per unit glucose and yielded more galactoglucomannans than those removed by steam. One of the galactoglucomannans from water prehydrolyzate had the highest number average molecular weight in this study: 3100 by end‐group assay, 3800 by osmometry; polysaccharides of even higher molecular weight were indicated by gpc prehumps. Several monomeric lignin degradation products were identified in the methyl ethyl ketone soluble fraction of steam prehydrolyzate. Among these were coniferaldehyde, vanillic acid, vanillin, protocatechualdehyde, phydroxybenozic acid and, unexpectedly, a sizeable proportion of dihydroconiferyl alcohol.
Investigation in the field of thermal degradation of grafted celluloses
Authors: Simionescu Cristofor I. , Schneider Ion Adam , Hurduc Natalia
Published: June 2010

In this work we tried to explain the thermal behavior of grafted celluloses. Using the thermogravimetric method with constant heating rate, we came to the following important conclusions concerning the thermal stability and the mechanism destruction: the thermal stability of cellulosic derivatives decreases comparatively with the cellulosic material used; the degradation mechanism is very complex occurring by concurrent reactions depending on the nature of the nature of the initial cellulosic support and the degree of substitution.
Determination of solubility parameters of chlorinated poly(vinyl chloride) by turbidimetry and viscosimetry
Authors: Tillaev R. S. , Khasankhanova M. , Tashmukhamedov S. A. , Usmanov Kh. U.
Published: June 2010

The product of chlorination of poly(vinyl chloride), perchlorovinyl (PerCV), dissolves in most organic solvents, a fact explained by the weakening of intermolecular interaction by irregular disposition of chlorine atoms along the chain. For evaluation of the changes in these forces, solubility parameters were determined by the method of turbidimetry and viscosimetry proposed by Suh, Clark, and Mangarai.

For turbidimetry 15 solvents of differing chemical nature and 2 nonsolvents were used: hexane (low solubility parameter) and methanol (high solubility parameter). Values of the intrinsic viscosity and Huggins constants were obtained from viscometric data. Consideration of the results in terms of the Flory‐Huggins theory gave a value of 9.30(cal/cm3)1/2 for the solubility parameter of PerCV.
Specific interactions in solutions of polymers. IV. A calorimetric study of butyl methacrylate oligomers in chloroform
Authors: Máša Z. , Biroš J. , Trekoval J. , Pouchly J.
Published: June 2010

Some general features of the concentration dependence of the reduced heat of mixing are derived for a system of nA moles of solvent and nB moles of polymer, provided that the enthalpy change referred to one mole of properly defined structural elements is expressed as a function of the fraction θB = cnB/(nA + cnB) where c denotes the number of structural elements in a polymer molecule. The heat of mixing ΔHM of a polymer with a solvent capable of binding to a macromolecule via specific interactions is analyzed on the basis of the association equilibrium theory. The effective number of binding sites ce, i.e., a value of c for which the curve ΔHM versus θB is symmetric, is defined as an invariant basis for characterization of the asymmetry of the enthalpy curve. Rules enabling conclusions to be drawn about the change of the binding constants with the degree of polymerization and with mutual interaction of the binding sites from an extensive parameter and the asymmetry are derived. Measurements have been carried out on the concentration dependence of the heat of mixing of mixtures of chloroform with butyl isobutyrate and with oligomers of butyl methacrylate (monomer to tetramer) having a butoxyl group on one chain end. In addition ΔHM for the reference mixtures chloroform + n‐heptane, chloroform + n‐hexadecane, tetrachloromethane + n‐heptane, n‐heptane + butyl isobutyrate was determined. A comparison of the enthalpy curves seems to prove that in the region of θB → 1 the binding constants, or enthalpies of dimer are only slightly lower than those for monomer, while those from dimer through tetramer coincide. On the contrary the binding affinity as θA → 1 decreases with increasing degree of polymerization. On the assumption that this decrease is given by a negative interaction between two occupied adjoining sites, the magnitude of this parameter has been estimated.
Cesium sulfate density gradient centrifugation of biological macromolecules in the presence of aprotic polar solvents
Authors: Hahn C. W.
Published: June 2010

The use of equilibrium centrifugation in concentrated aqueous solutions of cesium salts, for the analysis and the separation of biological macromolecules, is restricted because nonspecific interactions may lead to the aggregation and the precipitation (salting out) of a given macrospecies, or to associations and coprecipitation between different species.

On the assumption that these phenomena might be compensated for under certain conditions of preferential solvation, attempts were made to achieve pseudoideal conditions, by adding polar aprotic solvents to analytical and preparative cesium sulfate density‐gradient centrifugation of diverse preparations of desoxyribonucleic acid (DNA), ribonucleic acid (RNA), polysaccharides as extracted from biological material, and homopolynucleotides as synthesized by enzymatic methods.

The results of these experiments have shown that, thus modified, the technique makes it possible to reduce, if not avert, the precipitation of certain nucleic acids and polynucleotides, as well as the association between certain macromolecular species [4].

These advantages allow separations to be achieved which are impossible in conventional aqueous density gradients. In addition, the new technique permits the detection of macromolecular polysaccharides which normally would escape from detection, or which even would give rise to misinterpretation.

The purpose of this article is not so much to present new specific biological results, but rather to demonstrate that profiles obtained by the classical technique may be treacherously misleading, and that the new technique should, or at least may, be used in parallel to obtain complementary information.
The photochemical reactions of the peroxide radicals in polytetrafluorethylene
Authors: Milinchuk V. K. , Klinshpont E. R.
Published: June 2010

The kinetics and mechanism of the photochemical reactions of the peroxide radicals have been investigated in polytetrafluorethylene by electron paramagnetic resonance. Under irradiation by UV light, with λ < 300 nm, the peroxide radicals ˜CF2 CF(O2)CF2∼ and ∼CF2 CF2 O2 are dissociated and the end fluoralkyl radicals ∼CF2 CF2 are produced. The activation effective energy of the photodissociation of the peroxide radicals is equal to approximately 1‐2 kcal/mole. Quantum yield of the dissociation of peroxide radicals is equal to about 1. In the presence of oxygen the photorecombination of the peroxide radicals takes place. The photorecombination of the peroxide radicals bring about a reversal of the reactions of the dissociation of the end peroxide radicals and the addition of oxygen to the end fluoralkyl radical. Due to a dependence upon the initial concentration of peroxide radicals, the quantity of molecules of CF2 O produced varies from 25 to 45 per one vanished radical. The rate of the photorecombination of the peroxide radical is in linear dependence on light intensity and in the interval 150‐500 torr does not depend upon oxygen pressure.
The photodegradation of poly(vinyl chloride) films. III. The effect of peroxide additives
Authors: Gibb W. H. , MacCallum J. R.
Published: June 2010

The photodecomposition of films of poly(vinyl chloride) containing benzoyl peroxide and two aliphatic peroxides is investigated. It is proposed that the aromatic peroxide decomposed as a result of absorption of the irradiation, thus speeding up the early stages of the reaction but resulting in a lower final conversion. The aliphatic peroxides broke down as a result of energy transfer from polyenes and contributed to the propagation of the removal of HC1 with an increase in conversion. Films containing acenaphthene were ultimately more stable than the reference but decomposed faster in the early stages. It is suggested that energy transfer plays an important part in the mechanism.
The study of the inhibiting activity of poly (2‐methyl‐5‐ethynylpyridine) during initiated oxidation of cumene
Authors: Berlin A. A. , Aseeva R. M. , Ivanov A. A. , Kotova A. V.
Published: June 2010

The inhibiting activity of poly (2‐methyl‐5‐ethynylpyridine) (PEP) has been studied in the cumene oxidation reaction initiated by azobisisobutyronitrile at 55–65°C. According to the kinetic data the reaction between RO2 radical and PEP is irreversible. About 12% of the most active macromolecules of PEP react during the induction period followed by retarded oxidation of cumene. The quantity of terminated peroxy radicals reaches 1.5 per molecule of the inhibitor. This quantity is not altered when PEP concentration changes. Macromolecules of PEP differ in their radical reactivity. An increase of PEP molecular weight leads to the increase in PEP reactivity and in the fraction of active molecules. The paramagnetic centers of PEP interact with peroxy radicals at the maximum rate and disappear at the initial stage of oxidation.
Study of the inhibition effect of stable iminoxy radicals on the oxidation degradation of polymers
Authors: Matisová‐rychlá L. , Lazár M. , Rychlý J. , Karpukhin O. N.
Published: June 2010

The chemiluminescence method was used to study the reaction of peroxy radicals with stable radicals of X2NO. type where Corresponding courses of chemiluminescence intensity were followed either in low molecular solvents (ethyl benzene, dioxane) or in benzene solutions of polystyrene and in poly(ethylene oxide). The ratio ki/kt0.5 of rate constants of peroxy radicals and stable radicals recombination (ki) and mutual peroxy radicals termination (kt) was measured at 60°C. This value for ethyl benzene is 54.2 (1. mole−1 sec−1)0.5, for benzene 27.7 (1. mole−1 sec−1)0.5, and for 5% benzene solution of polystyrene 19.3 (1. mole−1 sec−1)0.5, respectively.

Similar systems in dioxane and poly(ethylene oxide) exhibited different courses of chemiluminescence intensity than those in ethyl benzene and benzene.
Metal compounds in free radical processes. I. Effect of copper (II) ion on the ligand reactivity in transfer reactions
Authors: Barton J. , Horanska V.
Published: June 2010

The reactivity of (‐)‐ephedrine, free or bonded in copper complex, in the transfer reactions with free radicals was studied. The reactivity of the ligand functioning as a hydrogen donor was expressed by the ratios of the rate constants of the interaction of 2,2′diphenyl‐1‐picrylhydrazyl (DPPH) with bis‐(−)‐ephedrine copper(II) chelate (k1), (−)‐ephedrine (k2), and cumene (k3). Thus the values 100 mole0.5 1.−0.5 and 2.5 mole0.5 1.−0.5 were found for the ratios k1/k2 and k1/k3, respectively. These data indicate a significant effect of copper ion on the reactivity of (–)‐ephedrine in the transfer reactions with DPPH radicals.
Chemical stabilization of polymers by unsaturated derivatives of 2‐mercaptobenzothiazole and 1, 2, 3‐benzotriazole
Authors: Saidov B. , Shakirova E. , Askarov M. , Bank A.
Published: June 2010

Statistic copolymers of methyl methacrylate, allyl‐2‐mercaptobenzothiazole or allyl‐1,2, 3‐benzotriazole, containing up to 10 mole % of the latter were studied. Using viscosimetric and infrared spectrometry methods it was shown that the increased content of certain stabilizing agents brings about an increased light stability effect in the polymer product.

Moreover, such properties were found to survive in graft copolymers of poly(vinyl chloride) and 2‐mercaptobenzothiazole and 1, 2, 3‐benzotriazole acrylic derivatives in the form of films and fibers.
Antioxidants and stabilizers. XXXVIII. Effect of the side initiation on the antioxidative activity of the hydroquinone derivatives
Authors: Lisá E. , Pospíšil J.
Published: June 2010

The stoichiometric factor of (2‐alkoxyalkyl), pivaloyl, hydroxy, methoxy, and alkyl derivatives of hydroquinone during the inhibited oxidation of tetralin has been determined. The differences observed in the antioxidative activity of the individual hydroquinone derivatives has been interpreted on the basis of different participation of the aryloxy radicals derived therefrom in the side initiation reaction leading to a reduction of the stoichiometric factor. The aryloxy radicals of hydroquinones with an intramolecular hydrogen bond in the molecule have been found to participate in this reaction to a limited extent only. This is one of the causes why these inhibitors have a higher stoichiometric factor than the alkyl derivatives of hydroquinone which does not form intramolecular bonds.
The sorption and diffusion of small molecules in amorphous and crystalline polybutadienes
Authors: Brown W. R. , Jenkins R. B. , Park G. S.
Published: June 2010

Diffusion coefficients of methylene chloride, chloroform, benzene, and 2,2,4‐trimethyl‐pentane in 1,4‐polybutadiene having trans contents between 2 and 100% have been obtained from vapor sorption and desorption kinetics. For amorphous polymers (trans content less than 70 to 80%) the diffusion coefficient at zero penetrant concentration decreases with increasing trans content and with increasing size of the diffusant. The activation energies for diffusion are independent of temperature and increase with trans content and diffusant size. Comparison with the activation energies for viscous flow give values for the B factor in Fujita's free volume theory and this increases with diffusant size towards a value of unity. At trans contents above about 80% a sudden drop in the diffusion coefficient and in the equilibrium vapor sorption occurs accompanied by a large increase in the concentration dependence of the diffusion coefficient. These changes result from the onset of crystallinity but the absence of any sudden change in the activation energy suggests that the main effect is a geometric one due to the inaccessibility of the crystalline regions with little change in the basic mechanism of diffusion in the amorphous regions. Vapor sorption enables calculation of the accessibility of the crystalline polymers and this is found to decrease with increasing size of the diffusant. Variations in crystallinity produced by different heat treatments give the expected variations in the diffusion coefficient and equalibrium vapor sorption.
Anionic copolymerization of methacrylates
Authors: Vlček P. , Doskočilová D. , Trekoval J.
Published: June 2010

An investigation was carried out of the anionic copolymerization of methyl methacrylate (M1), 2‐methoxyethyl methacrylate (M2), and 2‐(N, N‐dimethylamino) ethyl methacrylate (M3) in benzene solution at 20°C initiated with lithium tert‐butoxide. The monomer reactivity ratios (M1–M2) r1 = 1.51 ± 0.05, r2 = 2.10 ± 0.10, (M1–M3) r1 = 1.20 ± 0.10, r3 = 0.40 ± 0.05, (M2–M3) r2 = 1.40 ± 0.15, r3 = 0.60 ± 0.15 show that the reactivities of the individual monomers M1, M2, and M3 do not differ too much from each other. A study of the microstructure of copolymers M1–M2 by the NMR method revealed that at low conversions the tacticity of the copolymers depends on the concentration of 2‐methoxyethyl methacrylate in the starting monomer mixture; in the initial stage of copolymerization it is strongly dependent on conversion. Already a low content of M2 in the starting monomer mixture (below 1%) strongly affects the tacticity of the forming copolymer by depressing the content of the isotactic component.
Semi‐empirical calculation of reactivity ratios
Authors: Albert Richard , Malone William M.
Published: June 2010

From the specific refractive index, the UV absorption maximum is calculated which measures the difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Subtracting the HOMO‐LUMO energy from the π–π° transition energy of ethylene renders an estimation of the total π‐energy. The difference between the sum of the total π‐energies of reactants and the energy of the transition state approximates the activation energy and relates to the reactivity ratio.
The mechanism of cationic polymerization of β‐propiolactone
Authors: Ludvig E. B. , Khomyakov A. K. , Sanina G. S.
Published: June 2010

The mechanism of cationic polymerization of β‐propiolactone (PL) in methylene chloride under action of magnified image has been studied by the kinetic method. In the absence of additives, the process proceeds steadily via the active centers–acyl ions–and it involves the following reactions: 1. chain propagation, and 2. reversible combination of the active centers and carbonyl groups of monomer and polymer.

The dielectric constant of the medium affects the reaction in the range of low monomer concentrations. In the presence of ether and ester additives another combination reaction between the active centers and additives is observed. Kinetical treatment of the results was performed, and the ratios were determined for the respective equilibrium constants and the rate constant of chain propagation which are a measure of relative basicity of ethers and esters. Ketones were shown to be inhibitors of the process. The rate constants of chain termination were estimated for different ketones on the basis of kinetic data.
Influence of acids on the reaction rate of transesterification of dimethyl terephthalate
Authors: Šitter E. , Jalovecký J.
Published: June 2010

The reaction rate of transesterification of dimethyl terephtalate by ethylene glycol was investigated in the presence of some organic acids. The reaction rate decreased only slightly in the presence of monocarboxylic acids, usually forming anions of used catalysts; however the decreasing reaciton rate is very strong in presence of dicarboxylic acids. These acids can be present in ethylene glycol (oxalic acid), dimethyl terephtalate (terephtalic acid), or in any modifier. The monoester of terephtalic acid has a similar influence. The decrease of rate constant of a second order reaction during the reaction can be explained by the forming of carboxylic groups in the transesterification.
On the mechanism of hardening of resorsinol‐formaldehyde polyconden‐sates
Authors: Kurachenkov V. I. , Matyukhina O. S. , Silling M. I. , Stalnova M. A. , Igonin L. A.
Published: June 2010

The study of novolac resorcinol formaldehyde resin hardening was effected by means of the differential thermal analysis (under pressure) and IR‐spectroscopy methods. Two types of polycondensate were investigated. Paraformaldehyde and hexamethylene tetramine were used as hardeners. The existence of two regions of hardening, a low temperature range (100–120°C) and a higher temperaturer range (220–250°C) was revealed. Moreover, the influence of molecular weight, isomeric composition, and free resorcinol content on the hardening process was investigated. It was suggested that the existence of two regions of hardening is related to the different reactivity of β and γ positions in the resorcinol nucleus.
Copolymerization of propylene and complexed acrylonitrile by TiCl3–AlEt3 catalyst system
Authors: Dankovics A. , Szentivínyi Zs. , Kissin Ju. V. , Szöllösy I.
Published: June 2010

It was found that an equimolar complex is formed from acrylonitrile with triethylaluminum. The complex formation was verified by infrared spectroscopy. The original bands of acrylonitrile at 2235 cm−1 shifted and the new bands appeared at 2225 and 2275 cm−1. Copolymerization of acrylonitrile with propylene was proved to be possible with a TiCl3–AlEt3 catalyst system.

Kinetic studies on copolymerization of propylene with acrylonitrile showed that composition of the starting monomer mixture markedly influenced the course of the reaction and the acrylonitrile content of the copolymer.

Optimum conditions of the copolymerization reaction were as follows: temperature, 70°C; reaction time, 30 min; molar ratios of acrylonitrile to the metal alkyl and Al to Ti, 1:1 and 2;1, respectively, concentration of the total amount of monomers. Conversion is influenced by the aging time of the acrylonitrile‐metal alkyl complex; the yield is a linear function of the aging time. Composition of copolymers was determined by chemical analysis.
Zwitter‐ion polymerization of methacrylonitrile initiated by triethylphosphine
Authors: Ranogajec F. , Kotchetov E. V. , Markevitch M. A. , Enikolopyan N. S.
Published: June 2010

The mechanism of polymerization of methacrylonitrile initiated by triethylphosphine in dimethylformamide was investigated. It has been shown by elemental analysis that phosphorus is chemically bound to polymeric molecules. Analysis by NMR spectroscopy, as well as conductivity measurements prove that in the initiation process the following zwitterion structure: magnified image has been formed. Monomer addition to carbanion leads to macrozwitter‐ion. The role of free ions and ion pairs in macrozwitter‐ion polymerization are discussed. In the case of intramolecular formation of ion pairs, monomolecular equilibrium constant ion pairs‐free ions depends on the length of macrozwitter‐ion. Consequently, the polymerization rate depends on the length of the growing chain due to different reaction activity of ion pairs and free ions. By addition of salt, Ph3MeP+J−, in the polymerization system, i.e., by bimolecular formation of ion pairs the polymerization rate does not depends on the length of macrozwitter‐ion. Kinetics of polymerization in the presence of the salt was investigated. It was shown that terminated polymer also influences the polymerization rate and yield.
Modelling of the x‐ray scattering of polymers by light diffraction
Authors: Bodor G. , Samay G.
Published: June 2010

The x‐ray patterns of solid phase polymers are widely used to characterize the structures. They can be used, among others things, to calculate the degree of crystallinity, the crystalline particle size, and the lattice distortions. However, it is not perfectly clear how the characteristics of the structure effect the obtained diffractograms. The main aim of the present work is to explain what kind of diffraction patterns can be obtained from a hypothetical structure of a polymer. The effect of the following structural parameters were investigated: degree of crystallinity, crystalline particle size, lattice distortions of the first and second kind, and amorphous background. The changes of the diffraction patterns depending on these varied factors were followed.

The light diffraction patterns were produced by a modified Schlieren 80 apparatus. The polymer segments were modelled by point‐like scattering centers. From these, the models of an ideal crystal and the lattice distortion of the first and second kind were prepared. The crystalline particle size was varied by cutting the original mask. In the amorphous background the minimum distances of two scattering centers were altered. The light diffraction patterns were produced also by rotating the mask, and the x‐ray diagram of the unoriented polycrystalline samples could be reproduced. The intensities of the obtained patterns were measured by a microdensitometer. With the help of the diagrams, both qualitative and quantitative conclusions can be obtained about the relation between the mask and its diffraction pattern.
Selective interactions between macro‐molecules and two‐component solvents
Authors: Munk Petr , Allen Robert G. , Halbrook Michael E.
Published: June 2010

A new method of measuring the refractive index increment of a macromolecular solution while it is at equilibrium with a composite solvent is presented. A synthetic boundary is formed in the ultracentrifuge cell between the solution and composite solvent, which was not dialyzed against the solution. The solvent components equilibrate much faster than the macromolecules, and by proper extrapolation the refractive index increment of the macromolecules is obtained. Refractive index increments of a series of solutions of bovine serum albumin in guanidinium chloride solutions were measured and the amount of preferentially bound guanidinium chloride was calculated.
Influence of fillers on ethylene‐vinyl acetate copolymer degradation
Authors: Romanov A. , Marcinčin K. , Pollák V.
Published: June 2010

Mechanical degradation of ethylene‐vinyl acetate copolymer under use of oxalic acid, sodium chloride, basalt, and poly(vinyl chloride) as fillers has been studied. It has been found that the degree of degradation is affected by the reinforcement of the polymer matrix by the filler.
A mass spectrometry study of a connection between the mechanical and thermal degradation of polymers
Authors: Regel V. R. , Amelin A. V. , Pozdnyakov O. F. , Sanfirova T. P.
Published: June 2010

The influence of the “weak links” of real macromolecules on the kinetic parameters of thermal degradation and mechanical breakdown processes is suggested. This conclusion was made on the basis of studing and comparing the activation energies of these two processes for a number of polymers. The activation energy of the thermal degradation process was found by the mass spectrometry technique and the activation energy of mechanical breakdown was found by the results of mechanical tests.
Thermal degradation of vinyl copolymers as a function of their composition and sequence length distribution
Authors: Jaćović Mihailo S. , Milošević Danica
Published: June 2010

In order to study thermal degradation of copolymers and homopolymer mixtures of methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and styrene mild pyrolysis on a hot filament, followed by gas chromatography, was used. For each of the eight monomer pairs, at least eleven copolymers and eleven homopolymer mixtures of different composition were prepared for the study. It was suggested to present the results by plotting weight fraction of a monomer in the mixture of regenerated monomers vs. weight fraction of the same monomer in the copolymer or in the mixture of homopolymers. Ratio of the degrees of regeneration of two monomers can be obtained directly from such graphs. Taking the degree of monomer regeneration as an indication of the relative importance of depropagation and transfer, conclusions were made about the mutual influence of homopolymer sequences of two monomers in thermal depolymerization. A cosequence of this influence is the tendency for equalization of the degrees of regeneration of two monomers in the thermal degradation of the studied copolymers.
Dextran: A branched polymer and plasma expander
Authors: Cerny L. C. , Mc. Tiernan J. , Stasiw D. M.
Published: June 2010

The method of Flory and a modification of the method proposed by Elias and Cornet and van Ballegooijen were used to determine theta conditions for samples of dextran and poly(vinyl pyrolidone). Light scattering and viscosity measurements made at the theta condition for dextrans of widely ranging molecular weights showed the second virial coefficient to be zero and were in agreement with the theory of Zimm and Kilb for branched polymers. Viscosity and osmotic pressure measurements were made on various mixtures of dextran and poly(vinyl pyrolidone) in water and the theta solvents determined by the above methods. Osmotic pressure measurements for various mixtures of high‐molecular‐weight dextrans and poly(vinyl pyrolidone) made in water showed a minimum in the number‐average molecular weight and osmotic second virial coefficient at all three temperatures. This minimum did not occur in blends of a lower molecular weight dextran and poly(vinyl pyrolidone).