bluuebunny/crossref_metadata_2025 huggingface dataset:
Calorimetric studies of polycarboxylic acids in aqueous solution. II. Maleic acid–butyl vinyl ether copolymer
Authors: Crescenzi V. , Quadrifoglio F. , Delben F.
Published: June 2010

A calorimetric investigation of the heat of dissociation of a maleic acid‐butyl vinyl ether copolymer sample in aqueous solution has been carried out. Measurements were performed using dilute copolymer solutions (ca. 10−2 equiv/liter) in water, 0.04M NaCl, and 0.20M NaCl, respectively, at 25°C. Heat of dissociation data for the copolymer in water at 45°C are also reported. The calorimetric data allow evaluation in each case, (except for the solutions in 0.2M NaCl) of the enthalpy for the conformational transition which the maleic acid‐copolymer undergoes upon ionization. With the aid of potentiometric data the associated entropy changes are finally estimated. Our data point out the notable influences of temperature and of added simple salts on the energetics of the conformational transition.
Quenching of poly(vinyl phenyl ketone) photolysis by energy transfer in solution
Authors: Hrdlovič P. , Lukáč I. , Paška I.
Published: June 2010

The Stern‐Volmer constant of 40 quenchers was determined at 366 nm for poly(vinyl phenyl ketone) photolysis in benzene and dioxane solution at room temperature. Aromatic hydrocarbons, dienes and olefins were used as quenchers. A procedure for quantitative separation of the screening effect of quenchers absorbing at irradiation wavelength was elaborated. The correctness of this procedure was checked using 2‐hydroxy‐5‐methyl benzophenone over the concentration range 0‐10−3 mole/1. The values of the Stern‐Volmer constants lay within the range 0‐250 1./mole, expressing changes of the rate constant of quenching. Stern‐Volmer constants were found to be constant for naphthalene, its alkyl, halogen derivatives and esters at about 70 1./mole, that of 1‐naphtyl amine 1‐ and 2‐naphtol being, however, substantially higher. Electron‐deficient olefins were equally effective as dienes. There has not so far been found a parameter to characterize unambiguously the quenching efficiency of the compounds investigated.
Torsional braid analysis of lignin derived rubber stabilizers
Authors: Braddon D. V. , Falkehag S. I.
Published: June 2010

Several materials derived from kraft lignin have been shown to exhibit distinct antioxidant activity for the stabilization of raw rubber against heat accelerated degradation. Selected lignin derivatives alone or in combination with amine or sulfide antioxidants were effective stabilizers for an oil‐extended styrene‐butadiene rubber (SBR). Synergism with a phosphite has been demonstrated with unextended SBR.

Candidate stabilizers were screened using the relatively rapid torsional braid analyzer (TBA) technique. Pertinent samples were then tested with the conventional, but slower, technique of measuring Mooney viscosity. Mooney and TBA tests correlated for lignin derivatives, but the TBA predictions were low for typical commercial stabilizers such as phenyl‐beta‐naphthylamine (PBNA). Apparently the more volatile stabilizers, such as PBNA, escape during the aging process from the thin rubber sample employed in TBA testing. This observation limits the utility of the TBA technique to samples of similar and preferably low volatility.

Lignin derived stabilizers are unique in that they are non‐discoloring, nonstaining, and relatively low in volatility and cost.
Antioxidants and stabilizers. XLV. Oxidation of halogenated dihydric phenols with oxygen and its comparison with antioxidative activity
Authors: Lerchová J. , Pospíšil J.
Published: June 2010

Selected alkylated and halogenated derivatives of pyrocatechol and hydroquinone were oxidized with oxygen at 150°C in trichlorobenzene. The results allow an evaluation of participation of the direct oxidation of the antioxidant in the overall mechanism of its deactivation during the stabilization of polyolefins. Further data were obtained by oxidation performed in an alkaline medium. Specific relationships between the direct oxidation of halogenated dihydric phenols and their antioxidative activity in polypropylene and low‐molecular weight hydrocarbons are discussed.
Transport properties of nitrile polymers
Authors: Salame Morris
Published: June 2010

The transport properties of gases and vapors in high barrier polymers and copolymers containing nitrile functionalities are discussed. The permeation behavior of oxygen, nitrogen, carbon dioxide, and water vapor are given in detail. Polymers containing methacrylonitrile as well as acrylonitrile units are included: magnified image

Relationships of structure to permeability are given, in the light of known parameters for other polymers. A discussion of the Permachor values of nitrile polymers is presented, and methods of predicting permeation are given. Some anomalous behavior of transport under certain conditions are also presented.
Polyhydantions from glutamic acid
Authors: Santi E. , Babé S. G. , Fontán J.
Published: June 2010

Polyhydantoins have been prepared by a polyaddition cyclocondensation reaction of glutamic acid with aromatic diisocyanates in apolar medium (diphenyl ether).

The reaction takes place in two steps: in the first with the formation of polyamide‐ureas and thermal cyclation of them in a second step. These polyhydantoins are soluble in polar solvents and show good thermal stability.
Anionic polymerization of caprolactam. XLVI. Ketone forming units in anionic caprolactam and α‐methylcaprolactam polymers
Authors: Stehlíček J. , Čefelín P. , Šebenda J.
Published: June 2010

N, 2‐Disubstituted and N, 2, 2‐trisubstituted amides of 3‐oxocarboxylic acids represent the model moieties incorporated in the anionic polymers of lactams and α‐substituted lactams as a result of side reactions of the catalyst components. Aminoketones traced in polymers prepared by means of 3‐oxoamides as activators indicate the prefered mechanism of regeneration of the growths centers during polymerization. The presence of ketone units in anionic α‐methyl‐ε‐caprolactam polymers indicates condensation at the α‐carbon atom similarly as in the case of nonsubstituted caprolactam polymers.
Effect of temperature on the solid‐state polymerization of N‐tert‐alkylacrylamides
Authors: Zurakowska‐Orszagh J. , Zaleski B. , Gumulka A. , Busz W.
Published: June 2010

Following our former investigations on the radiation‐induced solid state polymerization of N‐substituted alkylacrylamides, we studied the effect of the temperature during irradiation for several selected monomers of this series namely: N‐tert‐butylacrylamide, N‐tertamylacrylamide, N‐tert‐hexylacrylamide, and N‐tert‐heptylacrylamide. Irradiations were carried out to high doses of conversion at temperatures varying in the range from 300°K up to temperatures near the melting point of particular monomers. The physicochemical properties of polymers obtained were presented as a function of the temperature and time of irradiation. The results show the effect of two competetive reactions; chain propagation in the solid state and interaction of radiation with the polymer formed. Both reactions occur at a different rate depending on the temperature and the corresponding mobility of the molecules in the solid state. Some interesting relations have been observed.
New hydrophilic materials for chromatography: Glycol methacrylates
Authors: Čoupek J. , Křiváková M. , Pokorný S.
Published: June 2010

Homogeneous and hetrogeneous crosslinked copolymers of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate were prepared by a suspension copolymerization in oil and water dispersion medium, respectively. The copolymers obtained were tested for their hydrolytic and thermal stability and found to be good gel chromatography packings with a broad range of applications.
Radiation induced grafting of butadiene to chlorinated polyethylene and poly (vinyl chloride)
Authors: Block Ira , Silverman Joseph
Published: June 2010

The radiation‐induced grafting of butadiene (BD) from methanol solution to films of low density polyethylene (LDPE), chlorinated polyethylene (PECL), and poly (vinyl chloride) (PVC) was studied as a function of chlorine content, dose rate, irradiation time, and BD concentration at room temperature. It was found that the graft yield to PECL increased with increasing glass transition temperature (Tg) of the polymer until the Tg of the chlorinated polymer was equal to the reaction temperature. As the degree of chlorination was increased beyond this point, little increase in graft yield was realized. Further increase in graft yield was obtained upon dilution of the monomer with methanol. The results are explained in terms of the effect of the added chlorine and absorbed monomer on the viscosity of the monomer‐swollen amorphous polymer.
Oligomeric initiators of radical polymerization on the basis of poly(phenylene toluylene esters)
Authors: Chuchin A. E. , Rozhkov V. V. , Fromberg M. B.
Published: June 2010

By the oxidation of some alkylene aromatic oligomers under soft conditions we succeeded in introducing into them peroxide‐type groups containing active oxygen. Such oligomers may be used as explosion‐proof initiators of radical polymerization of vinyl monomers. In addition to initiation, similar oligomers can act as agents, modifying the properties of the polymers obtained.

Oxidation in different solvents of poly (phenylene toluylene ethers) (PPTE), obtained by condensation of difterent substitutes of diphenyl ether of general formula X‐CH2 , where X = Cl, OH, OCH3, OC2H5, and Y = H or CH2 X, allows the introduction 0.2–0.5% of active oxygen into them. Stability of peroxide groups in oxidized PPTE has been estimated under various conditions. The initiating activity of oxidized PPTE in polymerization of styrene at 80° is arranged in succession depending on the nature of the X substitute: OCH3 > OC2H5 > Cl.
Infrared study on the nature of active centers in anionic polymerization
Authors: Basova R. V. , Koslova N. V. , Gantmakher A. R.
Published: June 2010

The active species structure in alkali metal‐initiated polymerization in different media has been investigated, living polydienes of low molecular weight being used as the main objects. An investigation of the IR spectra of living polydienes in the regions from 350 to 650 cm−1 and from 1500 cm−1 to 1700 cm−1 made it possible to find out the influence of the synthesis conditions on the metal‐carbon and carbon‐carbon double bond stretching frequencies in the active center. In alkali metal‐initiated polymerization of hydrocarbon monomers the character of the polymerization process is greatly dependent on the nature of alkali metal and the solvent. By comparison of the spectral data with the microstructure of polymers formed under the same conditions the possible structures of different types of active centers are discussed.
Polymerization and properties of optically active 2‐(para substituted‐benzenesulfo‐namido)‐3‐propiothiolactones
Authors: Fleš D. , Tomašić V. , Samsa M. , Ahmetović D. , Jerman B. , Fleš Melita
Published: June 2010

Optically active propiothiolactones I (R = OMe, Me, H, Cl, and NO2) were prepared by debenzylation of the corresponding 2‐para‐substituted‐benzenesulfonamido‐3‐benzyl‐mercaptopropionyl chlorides in the presence of 3 moles of aluminum bromide under the conditions of Friedel‐Crafts synthesis. The para‐substituted‐benzenesulfonamido‐propio‐thiolactones were polymerized in bulk and in DMF solution in the presence of benzyl mercaptan as initiator. The rate of polymerization was determined by measuring the change of specific rotation with time. The relative reactivity, expressed in logarithmic form, was plotted against Hammett's σ funtions showing a linear relationship, with reaction constant σ = –0.36. The temperature dependence of rate constants was determined and the activation energy in the polymerization of I (R = OMe, Me, and Cl) was determined: EA = 9.9 kcal/mole for I (R = OMe); 12.3 kcal/mole for I (R = Me), and 15.2 kcal/mole for I (R = Cl).
Chemical structure of radiation‐cured polyester resins
Authors: Funke W. , Schuh H.
Published: June 2010

The structure of electron‐beam‐cured polyester resins has been compared with that of the same resins which have been crosslinked by peroxide as a radical source. The copolymer chains of the radiation cured system are shorter, their composition more uniform, and the chain length distribution much smaller than with the peroxide cured resins. Polyester resins crosslinked by electron beams therefore have a more homogeneous structure than peroxide‐cured resins under usual conditions.
Formation of inhibiting active products from phenolic and amino antioxidants. III. Interactions of components of oxidized inhibitors
Authors: Gömöry Ivan , Gömöryová A.
Published: June 2010

During the induction period of oxidation of polymers inhibited with phenolic and amino antioxidants, inhibiting active products are formed by oxidative transformations of original inhibitors. The interactions of the components of oxidized inhibitors were investigated by the oxidation of polyethylene inhibited by binary mixtures of particular components. The mutual interactions were determined by varying the weight ratio of both components of the binary mixture and by evaluating the deviations from additive dependence of the induction period on composition of the binary mixture. The results indicate that the type of the interaction and the quantitative effect are very sensitive to the composition of the binary mixture and to the experimental conditions of the oxidation–the temperature and the summary concentration.
Decomposition mechanism of the cumyl hydroperoxide‐sodium methyl sulfite catalytic system in the low temperature bulk polymerization of vinyl chloride
Authors: Patron L. , Mazzolini C. , Moretti A.
Published: June 2010

The redox system cumyl hydroperoxide (C)‐sodium methylsulfite (A) is a very effective initiator for radical low‐temperature polymerizations. In previous works a mechanism for the decomposition of this catalytic system was suggested, but not supported by experimental evidence; owing to the high decomposition rate of the catalyst the polymerization kinetics were followed using an adiabatic reactor working as a calorimeter. The experimental results give evidence for a bimolecular mechanism of reaction between C and A giving place to oxycumyl and sulfonic radicals. The rate constant of the bimolecular reaction resulted to be 0.85 mole−1 liter sec−1 at −30°C. The activation energy, measured in the range −20 to −50°C, was calculated as 8.3 kcal/mole, in agreement with the proposed decomposition mechanism.
Über die mit titanchlorid‐triäthylaluminium katalysator initiierte propylenvinylchlorid copolymerisation
Authors: Dankovics A.
Published: June 2010

The copolymerization of propylene and vinylchloride with a TiCl3–Et3Al system is possible in the presence of polar complex‐forming additives. The presence of diphenylamine is nessesary but not enough to complete the reaction. If the complex‐forming ether‐amine mixture has a high mole ratio, the composition of the copolymer can be changed only in a small range. But when the ether‐amine mole ratio is low, one can change composition of the copolymer at will. The presence of the complex‐forming additives increase the conversion considerably. It is very important that the vinyl chloride be neat. If the vinyl chloride is contaminated with other chlorinated hydrocarbons, the reaction does not take place. If the vinyl chloride has a small acetylene content, it does not disturbe the copolymerization. Several properties of the copolymers change proportional to the composition. The copolymers have lower heat stability than the homopolymers.
The analysis of four point diagrams of branched, cold stretched polyethylene
Authors: Loboda‐Čačković J. , Čačković H. , Hosemann R.
Published: June 2010

A combined analysis of small and wide angle X‐ray scattering (SAXS and WAXS) is carried out on cold stretched rods of bulk polyethylene (PE) with various branching rates (BR). If the BR is higher than 0.6%, all crystalline layer domains are always tilted against the fiber direction by about 25° around the b‐axis. For smaller values of BR, a component appears which is not tilted. This tilt is explained by the branches which are predominately located in the “amorphous phase” of the ultrafibrils. Under these assumptions, a formula is derived which shows that the 25°‐turn takes place if the mean distance between neighboring branches in a chain is so small that not more than one backfolding can take place without a branch. With increasing BR the theory predicts that the thickress of the amorphous layers becomes larger. The lateral size of the microparacrystals is always about 50 Å and defines the diameter of the ultrafibrils. During annealing, families of ultrafibrils aggregate and build up paracrystals of ∼ 100 Å lateral size and more, which turn around the b‐axis by 25° as a whole, to form paracrystalline layer domains orthogonal to the fiber.
Some peculiarities of the reaction of sulfur with rubber
Authors: Markov V. V. , Privalikhina N. P. , Zanemonets N. A.
Published: June 2010

The allotropic transformations of sulfur considerably affect the amount of the vulcanization heat and its changes under different phases of reactions. Heat effect depends on the chemical contents of oil plasticizers, though the last do not enter the chemical reaction with sulfur in the presence of rubber.

It was supposed that plasticizers affect the nature of allotropic changes of sulfur in the initial phases of the reaction.
Study of the compatibility of plasticizers with poly(vinyl chloride) by dielectric spectroscopy
Authors: Kisbényi Mária
Published: June 2010

Dielectric spectroscopy has been applied for studying the compatibility of plasticizers with poly (vinyl chloride) as well as for detecting the phase‐inhomogeneities of plasticized systems.

Commercial plasticizers having different polarity and compatibility with the polymer have been investigated. The effect of insufficient processing as well as storage and annealing on the physical structure of the compounds are also discussed.

For obtaining dielectric spectra, the real and imaginary parts of the dielectric permittivity of liquid plasticizers and plasticized compounds were recorded continuously as a function of temperature in the range from −170 up to +200°C at fixed frequencies and heating‐cooling rates. Exudation, the weight loss of the plasticizer, as well as mechanical properties were measured comparatively.

It is a generally accepted fact that the compatibility of a plasticizer with a given polymer depends upon their dielectric properties. According to our observations, the temperature dependence of the dielectric permittivity of the plasticizer is of great importance from this point of view, especially in the range of application of the plasticized system. Comparing the dielectric dispersion spectrum of a liquid plasticizer to that of the corresponding plasticized compound, conclusions about the compatibility can be derived. A special polarization is found to be originated from the phase‐separation and from the inhomogeneities.

Besides the dielectric polarization arising from the polymer chain and plasticizer dipoles, the dielectric spectra show the existence of an interfacial, Maxwell‐Wagner type polarization, which is found to be dependent on the inhomogeneities of the texture of the compound.
Investigation of the binary system of a crystalline monomer and its polymer
Authors: Hardy Gyula , Cser Ferenc , Takács Erzsebet
Published: June 2010

Systems formed by crystalline monomer and polymer can be characterized by their phase diagram. From the view point of the composition, this diagram can be divided into two main parts at a certain ratio designated here as Mkr. At polymer contents higher than Mkr, the system shows the behavior of plasticized polymers. At polymer ratios lower than this value, crystalline monomer appears in the system. In this latter case the phase condition means the thermodynamic relationship of the crystalline monomer and the plasticized Mkr composition polymer therefore can be explained as a solubility function.
Bicomponent fiber structures on polypropylene basis
Authors: Geleji Frigyes , Druzsbaczky Gabor
Published: June 2010

Bicomponent fibers were spun in a combination of two different polypropylene polymer melt streams. The different polymers were prepared from a single polymer by dividing the polymer flow into two streams and exposing them to different thermal influences. Individual fibers also were spun from the different polymer streams in order to investigate their molecular and mechanical properties. Mechanical properties of the bicomponent fibers and the molecular characteristics of their components were correlated.
Studies of single spherulite deformation. I
Authors: Pakuła T. , Gałeski A. , Kryszewski M.
Published: June 2010

In this work a mechanical model of deformation of two‐dimensional spherulites is proposed taking into consideration its two phase structure (amorphous and crystalline phase) as well as the internal radial correlation of orientation of crystalline elements. On the basis of the proposed model, assuming specific properties of amorphous and crystalline phases, the changes in shape and in internal orientation within the spherulites, related to a given strain, have been calculated. Using the derived relations the distribution of the intensity in low angle light scattering patterns on deformed spherulites has been obtained. Theoretical results were compared with these obtained from experimental low angle light scattering and optical microscope studies on deformed spherulites in polyoxymethylene.
Polymer configuration in bulk: Neutron diffraction by deuterated polymers in a nondeuterated matrix
Authors: Cotton J. P. , Farnoux B. , Jannink G. , Picot C. , Summerfield G. C.
Published: June 2010

Small‐angle neutron scattering (SANS) by mixtures of labeled and unlabeled polymers is determined by the “contrast factor”. A formulation of this factor and its value for deuterated‐nondeuterated polystyrene and polyethylene systems are given. Some examples of neutron scattering by these systems in the bulk and liquid states indicate that the labeled‐chain signal is important and clearly allows the determination of the single‐chain characteristics.
Property‐structure relationships in poly‐urethanes: Infrared studies
Authors: Macknight W. J. , Yang M.
Published: June 2010

Temperature dependent infrared studies have been carried out on three series of poly‐urethanes previously synthesized and characterized. The repeat units of the three series may be schematically represented as follows: magnified image In each case n varies from 2 to 10. The H and DP series are partially crystalline while the 4M series is entirely amorphous.

It was possible to draw several conclusions concerning the hydrogen bonded NH and Cbond;O groups in these polymers. These conclusions are: (1) The aromatic polyurethanes of the DP and 4M series are hydrogen bonded in the amorphous phase below the glass transition temperature, (Tg), to the extent of 75% or less whereas the aliphatic H series is completely hydrogen bonded below Tg. (2) Both the DP and H series are completely hydrogen bonded in the crystalline phase below the melting point, (Tm), regardless of the value of n. (3) A temperature dependent equilibrium between free and hydrogen bonded NH groups occurs in the amorphous phase above Tg in all three series. (4) The temperature dependences of the total area of the NH stretching bands exhibit transitions corresponding to Tg, Tm, and, in the case of the H series, to a first order crystal‐crystal phase transition, Tt. (5) The temperature dependences of the frequencies of the hydrogen bonded NH stretching vibration also exhibit transitions corresponding to Tg and Tm.
The crystallization kinetics of highly crystalline polymers
Authors: Stafford J. W.
Published: June 2010

A phenomenological investigation of the crystallization kinetics of polyethylene indicates that there are three distinct phases in the process. This viewpoint is substantiated by a mathematical analysis of actual crystallization data. The limited applicability of a rate equation based on expanding spheres is clearly demonstrated.
Investigation of conformations of macro‐molecules and crystalline structure of aromatic polyimides
Authors: Koltsov A. I. , Baklagina Yu. G. , Ginzburg B. M. , Korzhavin L. N. , Koton M. M. , Mikhailova N. V. , Nikitin V. N. , Sidorovich A. V.
Published: June 2010

The structures of four stretched polymides obtained by chemical and thermal imidization of the condensation products of pyromellitic acid dianhydride with diamines [4,4′‐diaminodiphenyloxide (PI‐2) and bis‐4‐aminophenylhydroquinone ether (PI‐3)] and of the condensation products of paraphenylene‐bis‐trimellitate dianhydride with the same diamines were studied by x‐ray analysis, polarized IR spectroscopy, and pulsed magnetic resonance. The crystalline unit cell parameters have been determined. Polymer chain conformations suggested on the basis of x‐ray analysis were supported by IR and PMR spectra. The PMR data allow us to accept the torsional oscillations of aromatic rings around their bonds with neighboring O and N atoms as the main form of molecular mobility at room temperature.
Solution behavior of ethylcellulose in organic solvents
Authors: Meyerhoff G. , Sütterlin N.
Published: June 2010

Ethylcellulose has been investigated by osmotic pressure, sedimentation‐diffusion, and light scattering measurements in dilute solutions of acetone, ethylacetate, 2‐butanol, n‐butylchloride, and benzene. Combining the results of different measuring techniques allowed the recognition and elimination of the influence of microgels present in the solution. The observed second virial coefficients are high as compared with those of the vinyl polymers and do not show a pronounced dependence on the type of solvent. On the other hand, the radius of gyration is nearly proportional to the root of the molecular weight. This behavior is discussed in connection with results on other cellulose ethers reported in the literature.
Excess functions in polymer solutions
Authors: Rätzsch Margit , Krahn Gerhard
Published: June 2010

By means of a modified Scatchard‐Hildebrand equation the excess Gibbs energies will be calculated for systems consisting of aromatic compounds and saturated hydrocarbons from molar volumes and solubility parameters and they will be compared with experimental data. A way of calculating the solubility parameters of high molecular hydrocarbons from solubility parameters of low molecular hydrocarbons will be suggested and the applicability of the Scatchard‐Hildebrand equation to polymer solutions will be studied.
Mechanism of the thermal degradation of poly(vinyl chloride)
Authors: Troitskii B. B. , Troitskaya L. S. , Myakov V. N. , Lepaev A. F.
Published: June 2010

The kinetics for dehydrochlorination and benzene formation has been studied during the degradation of two samples of poly(vinyl chloride) (PVC) at 180–200°C under vacuum with and without the removal of hydrogen chloride. The effects of various additives, such as organic phosphites, mercury, silver, gold, and glass upon the thermal degradation of PVC were investigated. Mercury, silver, and glass decrease the rate of autocatalytic dehydrochlorination of the polymer in the presence of hydrogen chloride but silver and glass do not affect PVC degradation rate in the absence of HCl. PVC thermal decomposition under vacuum with removal of HCl mostly proceeds by a molecular mechanism. At the same time, radical reactions take place. But there are some very endothermic stages of chain propagation, this is why in this case, the radical mechanism of PVC dehydrochlorination does not compete with the molecular one. In the presence of HCl, the rate of radical reactions increases and predominates over rate of molecular reactions.
Relation between thermal degradation and tacticity of PVC
Authors: Millan J. , Carranza M. , Guzman J.
Published: June 2010

The thermal degradation up to 0.3% at 180°C of sets of PVC prepared in such a way that samples have different tacticity has been studied by conductimetric methods. The degradation rates of PVC were found to depend on the syndiotacticity content; the plots of degradation rates as function of a tacticity parameter show a minimum at which the corresponding polymers are very stable. The kinetic results as well as the shape of UV‐visible spectra of degraded polymers suggest an influence of tactic sequences on propagation step.

The degradation of vinyl chloride copolymers with diethyl fumarate, isobutylene, and vinyl bromide, having the same composition but very different tacticity in PVC sequences, was also studied under the same conditions. For each pair of copolymers, the higher degradation rate was always that of the sample having more syndiotactic sequences.
Aggregation of polyoxyethylene in dilute solutions
Authors: Carpenter Dewey K. , Santiago German , Hunt Ann H.
Published: June 2010

Light scattering as a function of scattering angle, concentration, and temperature reveals that polyoxyethylene (POE) forms large aggregates in benzene and chloroform, while in methanol and dioxane almost complete molecular dispersion occurs. Although the solutions containing large aggregates contain a distribution of molecular weights, the angular envelopes of c/R (θ) versus sin2θ/2 exhibit pronounced upward curvature, indicating that the aggregates are dense structures such as spheres or highly branched coils. In methanol, the angular envelopes exhibit moderate downward curvature, reflecting the essentially molecularly dispersed character of the solution and the breadth of the molecular weight distribution. In filtered solutions of dioxane, a tendency exists for minima to occur in the angular envelopes; this can be rationalized in terms of the anisotropy of the scattering. The polarized components of the scattered intensity VV, HV, VH, and HH were studied in the scattering plane. For the large aggregates HV is angular dependent, while in methanol and dioxane HV is independent of angle. Heating or cooling a POE solution in benzene followed by a study of the angular envelope, shows that the aggregates are stable. Hydrodynamic measurements fail to detect the existence of the aggregates. Taking all the data into consideration, the large aggregates appear to be compact, extensively branched, anisotropic, and stable.
Kinetic discussion on the catalysis of copper‐partially‐quaternized poly‐(vinylpyridine) complexes
Authors: Tsuchida Eishun , Nishide Hiroyuki , Nishiyama Toshio
Published: June 2010

2,6‐Xylenol was oxidatively polymerized by Cu‐poly (vinylpyridine) (PVP) complex or Cu‐partially‐quaternized PVP (QPVP) complex in a homogeneous dimethylsulfoxide solution, and the mechanism of the catalysis of the polymeric Cu complexes was discussed. The polymerization rate increased in the following order: Cu‐pyridine <Cu‐PVP<Cu‐QPVP. The catalytic activity of the Cu‐QPVP complex exhibited a maximum in the region where the percentage of quaternization of QPVP was 20‐50% and tended to increase with the degree of polymerization of QPVP. Considering through the kinetic constants of the polymerization, the neutral salt effect, and the influence of the monomer species, it was cleared that the higher activity of the Cu‐QPVP catalyst was attributed to the electrostatic interaction between the QPVP complex and the anionic monomer. That is to say, the intermediate complex, to which xylenol is coordinated, is enthalpically stabilized due to the electrostatic field of the QPVP complex. Activation entropy ΔS† of the polymer catalyst was larger in comparison with the monomeric analog, and the larger ΔS†S was observed in the PVP system and the neutral‐salt‐added QPVP system, of which structures were compact. It is considered that the frequency factor of the dissociation step of the activated monomer increases because of the high density of cupric ion in the polymer complex.
Butadiene‐propylene alternating copolymers
Authors: Furukawa Junji
Published: June 2010

A general account is given of the alternating copolymer of butadiene with propylene. The copolymerization can be carried out at low temperature in the presence of V‐ or Ti‐based, modified Ziegler‐Natta catalyst which is prepared at a very low temperature (‐70°C). The structure of the copolymer was investigated by ozonolysis and 220 MHz NMR spectroscopy. A high degree of alternation, more than 97%, has been confirmed. For copolymerization a mechanism involving alternating coordination of olefin and diolefin is proposed. Finally, physical properties such as green strength, dynamic moduli, processability, etc., are illustrated in an application as a synthetic elastomer. The copolymer exhibits high strength and elongation at break perhaps because of induced orientation. The stress‐strain behavior is discussed in terms of a theory of elasticity and it is concluded that the alternating copolymer may have a flexible chain in spite of the trans‐structure of the butadiene unit.
Effects of gamma radiation on copolymers of styrene and methyl methacrylate in the solid state
Authors: Busfield W. K. , O'Donnell J. H.
Published: June 2010

Random copolymers of styrene and methyl methacrylate, prepared by free radical polymerization in bulk at 60°C, were irradiated under vacuum at 35°C with 60Co gamma rays to doses up to 200 Mrad. The flexural strength, with failure occurring in all cases by brittle fracture, decreased with radiation dose; the rate of this decrease increased with increasing methyl methacrylate content. Compressive strength measurements showed a transition from yield to fracture after a radiation dose which increased with styrene content and then a rapid fall in fracture stress for higher doses. Viscometry measurements showed a good correlation between changes in flexural strength and molecular weight.
Hydrobromation des Polyalcadiènes par les Réactions Couplées D'Hydroboration et de Bromation
Authors: Pinazzi C. P. , Derouet D. , Brosse J. C.
Published: June 2010

L'hydrohalogénation spécifique totale, à l'aide des réactions couplées d'hydroboration et de bromation a été étudiée sur des polybutadiènes et des polyisoprènes de synthèse, de faible masse moléculaire et de microstructure définie. L'hydrohalogénation, à l'aide de ce type de réactions, comprend d'abord l'hydroboration des doubles liaisons carbone‐carbone à l'aide du bora‐9 bicyclo [3.3.1] nonane et, ensuite, la bromation par le brome de l'organoborane macromoléculaire formé. Le brome se fixe en position Anti‐Markovnikoff, par rapport à l'alcène de départ.

Les résultats obtenus ont permis de noter que les doubles liaisons carbone‐carbone internes (microstructures‐1,4) étaient beaucoup plus réactives que les doubles liaisons carbone‐carbone terminales (microstructures‐1,2 et ‐3,4) et que, plus le polyalcadiène de départ était riche en motifs‐1,4, plus le taux de motifs hydrobromés était élevé. En outre, les polymères hydrobromés formés à partir de polyalcadiènes de microstructure‐1,4 prédominante sont beaucoup plus faciles à isoler et à purifier.
Polycondensation, D'Acides α‐Aminés à L'Aide D'Un Couple Oxydant‐Reducteur (Hg++ OU I2 — Phosphites)
Authors: Guilly Lionel Le , Spach Gerard
Published: June 2010

On a montré que l'action d'un couple d'agents, l'un oxydant (Hg++ ou I2) et l'autre réducteur (phosphite de diéthyle) sur des acides α‐aminés libres en milieu pyridine conduit à la formation de polypeptides. La signification prébiotique d'un tel système est discutée.
Synthesis and characterization of heat‐resistant aromatic and benzothiazolic linear polyethers
Authors: Blaise C. , Bouanane A. , Brembilla A. , Lochon P. , Neel J.
Published: June 2010

A series of high molecular weight polyethers has been prepared by polycondensation of alkaline bisphenoxides with various reagents containing two 2‐chlorobenzothiazolic moieties. A general scheme for the synthesis of these heterocyclic bifunctional derivatives is given and a preliminary kinetic study is reported which demonstrates that they are sufficiently reactive to polycondense readily with bisphenoxides. Details are given of the polycondensation procedure (solvent, concentration, temperature, polycondensation period, yield in polymer recovered). The assumed structures of the resulting polymers were corroborated by elemental analysis and infrared spectroscopy (by comparison with the spectra of low molecular weight analogous model compounds). The new polyethers generally display a good solubility in solvents such as tetrachloroethane, dichloroacetic acid, N‐methyl‐2‐pyrrolidone, sulfolane, quinoline, and pyridine. Colorless and transparent films were readily cast from these solutions. Thermal properties of these materials were evaluated by thermogravimetric analysis and differential thermal analysis carried out with powdered samples. Most of them proved to be stable when heated in air around 350°C.
Utilisation De La Chromatographie Sur Gel Dans Le Domaine Des Molecules Organiques De Forte Masse Et Des Macromolecules De Faible Masse
Authors: Aurenge J. , Gallot Z. , de Vries A. J. , Benoit H.
Published: June 2010

On a cherché à étendre l'utilisation de la chromatographie sur gel au domaine des molécules organiques de forte masse et des macromolécules de faible masse. On a montré que l'etalonnage universel en volume hydro dynamique et l'etalonnage en volume molaire peuvent ětre utilisés dans le cas des petites molécules si la séparation sur le support chromatographique n'est pas perturbée par des phénomènes d'adsorption.
Ring‐chain competition in a branched polycondensate system
Authors: Ross‐Murphy Simon B.
Published: June 2010

In this paper, the kinetics of copolyesterification of the well studied branching system formed by the reaction of 1,3,5‐tri(carboxymethyl)benzene, (BTA), and decane‐1, 10‐diol, (DMG) are described with special reference to the relative rates of inter‐ and intramolecular reactions (ring‐chain competition). The conversion β at time t, and the gel point βc were measured by continuously monitoring the pressure of steam evolved in a closed system at 175°C. during the course of polycondensation, using a pressure transducer.

Experiments were carried out using 1,3,5‐tri(diphenylmethylcarboxymethyl)benzene as a diluent to further encourage intramolecular reaction. The experimental ratecurves passed smoothly through the gel point, and agreed well with those rate curves calculated using the “spanning tree” model of cascade theory, until substantially after the gel point. The overall reaction order was very close to the third order (acid self‐catalyzed) kinetics expected from studies of simple esterification.

The amount of cyclization in the BTA/DMG system was confirmed to be small. Less than 1.2% of links are formed intramolecularly, at the gel point, βcβc was found to be 0.718 ± 0.006, compared to 0.707 i.e., 2−1/2 for a random 2:3 functional alternating copolycondensation. The small difference indicates that the BTA/DMG system is the closest approach yet to a random tree‐like network.
Cyclization in crosslinking polymerization. II. Chain polymerization of a bis unsaturated monomer (polydisperse case)
Authors: Dušek K. , Ilavský M.
Published: June 2010

The procedure suggested for the description of ring‐chain competition in the polymerization of a bis unsaturated monomer derived in Part I for monodisperse primary chains was extended to include the case of polydisperse primary chains. The cyclization probability and differential fractions of units in the chain are regarded as different for each group of r‐mers. The composition of primary chains remains practically unchanged at r > 100, and the summations were therefore truncated at r = 100. Model calculations show that trends in the composition change of the polymer and of the gel point as a function of the degree of polymerization of primary chains, of the distribution width, and of dilution are in accord with experimental findings. Comparison with the data published on the polymerization of dialiyl phthalate (with a marked cyclization and short primary chains) has revealed that the model is generally satisfactory, but that it somewhat underestimates cyclization because of the neglected effect of cycles on the conformational statistics of chains, or the neglected effect of excluded volume. This is particularly reflected in a lower calculated conversion at the gel point. This underestimation may partially be compensated for by assuming a higher chain flexibility.
Curing kinetics of epoxy resins
Authors: Olcese Tito , Spelta Osvaldo , Vargiu Silvio
Published: June 2010

Curing kinetics of some epoxy systems was studied by means of differential scanning calorimetry. We examined the influence of a few nitrogenous curing agents with different chemical structures on the rate of curing; different levels of the accelerator were tested. We also investigated the influence of two different resins on the rate of curing. The calorimetric measurements were performed in isothermal conditions and at different scanning rates. The experimental plot of the curing rate was checked by comparison with some theoretical equations, and information was collected on activation energies, reaction orders, and temperature influence.
Diffusion and sedimentation of serum albumin in concentrated solutions
Authors: Kitchen Robert G. , Preston Barry N. , Wells John D.
Published: June 2010

We have measured the self‐diffusion coefficient, D, of serum albumin (by the open‐ended capillary method) and the mutual diffusion coefficient, Dm, for serum albumin solutions (by the capillary method, and in the ultracentrifuge) at concentrations up to 0.2 g°Cm−3. Our self‐diffusion data follow those of Keller et al. [J. Phys. Chem., 75, 379 (1971)], but we can find no experimental support for their contention that Dm = D at high concentrations. Indeed, our results closely follow the theoretical relation Dm = D (1 – cv)(1 + 2A2 Me +…).

Where c, v, A2, and M are, respectively, the concentration, partial specific volume, second virial coefficient, and molar mass of serum albumin.

We have also studied the concentration dependence of the frictional coefficients in diffusion and sedimentation. The two frictional coefficients are equal only in very dilute solutions of serum albumin.
Improved thermoplastic elastomers through cationic polymerization
Authors: Sigwalt P. , Polton A. , Miskovic M.
Published: June 2010

Cationic grafting has been realized on three types of elastomers that contain either reactive allylic or alkyl chlorides (acting as cocatalysts) or double bonds (“direct grafting”) or both (e.g., chlorobutyl rubber). In the case of chlorobutyl rubber, polymerization yields were always 100%, and grafting efficiencies (percentage of grafted indene over total indene) were often near 100%. The best results were obtained when grafting a copolymer of indene and α‐methylstyrene around −50°C. (The polymer obtained has a tensile strength of 130 kg/cm2 at 20°C and 50 kg/cm2 at 100°C.) Grafting of indene on chlorinated ethylene‐propylene copolymers could be made with grafting efficiencies of about 70%. Direct grafting of indene on nonchlorinated unsaturated elastomers, such as EPDM rubbers, has been made with grafting efficiencies higher than 50%. In this case, grafting could be realized around 0°C. The various reactions that influence the grafting efficiencies are discussed: initiation involving the polymer chain, grafting through termination on double bonds, transfer to monomer, and transfer to polymer.
The nature of propagating species in cationic polymerization of vinyl compounds
Authors: Higashimura Toshinobu
Published: June 2010

A suitable combination of the stability of propagating carbocation and the nucleophilicity of counterion is necessary in general for the formation of polymers with a bimodal molecular weight distribution: for styrene or p‐chlorostyrene, less nucleophilic counterions (ClO4−, CF3SO3−) are suitable; for p‐methyl‐or p‐methoxystryene, highly nucleophilic I3− or I− is required. In the styrene polymerization with ClO4− or CF3SO3− as counterion, the common‐ion salt effect on the molecular weight distribution and the steric structure of the polymer suggest that two kinds of ion pairs as well as free ions are involved in the cationic polymerization. These species have been found to be different not only in reactivity in homopolymerization but also in monomer selectivity in copolymerization.
Thermal degradation of polyethylene in a nitrogen atmosphere of low oxygen content. IV. Structural changes occurring in different types of high‐density polyethylene
Authors: Holmström Arne , Sörvik Erling M.
Published: June 2010

The thermal and thermo‐oxidative degradation of reprecipitated and “as received” samples of different types of high‐density polyethylene (HDPE) have been studied. Two of the samples were of conventional Phillips type, being essentially linear and having one vinyl group per molecule. The other two HDPE's were also produced by chromium catalysts, but according to Union Carbide's fluidized bed process. In one of these resins the molecules had vinyl end groups while the other resin was fully saturated.

Contrary to earlier statements concerning the thermal degradation of polyethylene it was found that HDPE is not degraded according to a random scission type of mechanism. Instead both molecular diminishing and enlargement are found to occur simultaneously. This is, however, in accordance with our recent findings on low‐density polyethylene (LDPE).

The samples were heated at temperatures between 284 and 355°C under high purity grade nitrogen during thermal degradation and under nitrogen containing up to 1.14% oxygen during thermo‐oxidative degradation. Changes in molecular weight distribution and degree of long chain branching (LCB) were followed by gel chromatography and viscosity measurements. Other structural changes were investigated by infrared spectroscopy and differential scanning calorimetry. Both reprecipitated and “as‐received” samples gave identical results.

For all the HDPE's an increase in heating time and temperature and oxygen content was found to increase the formation of low molecular weight material, long chain branches, volatile products, carbonyl‐, ether‐, and olefinic groups, discoloration, and insoluble material. Although there was much in common between LDPE and HDPE there were also certain noticeable differences, even within the HDPE group. These differences are suggested to be due to different catalyst residues in the HDPE's causing, e.g., the fully saturated material to degrade at 100°C lower temperature than expected.
Crystallization and structure of degraded branched polyethylene
Authors: Rybnikář F.
Published: June 2010

The experimental results of an x‐ray diffraction and electron microscope study show that the degradation process taking place during extrusion of branched polyethylene leads to structural changes which influence the number and size of lamellar spherulites, crystallization rate, and the character of the lamellar morphology.
The effect of the chemical and physical properties of carbon black on the thermal and photooxidation of polyethylene
Authors: Kovács E. , Wolkober Z.
Published: June 2010

The antioxidant and UV stabilizing effect of different carbon blacks on parafin oil model compound with and without additional stabilizers was investigated. The thermal and photooxistabilities of the samples were characterized by the induction period of the oxygen consumption which was measured volumetrically in a closed system filled with oxygen. A relationship was established between the induction periods of the thermal oxistability curves and the distributions of oxygen content within the active groups of the blacks.

Determining the stabilities of the polymer‐black‐antioxidant systems, synergistic and antagonistic phenomena were observed. These effects were explained by taking nto account the quality and amount of the active sites of the blacks.

The photooxidation experiments corroborated the double role of the black as UV stabilizer. Primarily it acts as a UV screen, its effectiveness being proportional to its specific surface. In addition to this, the synergism and antagonism observed in the ternary systems suggested that the carbon was also involved in the photooxidation as a chain terminating and peroxide decomposing agent.