bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colligative properties of polyelectrolyte solutions. VI. Donnan membrane equilibrium
Authors: Nagasawa Mitsuru , Takahashi Akira , Izumi Mikio , Kagawa Ikumi 
Published: April 2003

AbstractThe Donnan membrane equilibrium of a linear polyelectrolyte solution was studied, using sodium polyvinyl alcohol sulfate as the sample and sodium chloride as the diffusible salt. Simultaneous measurements of membrane potential, sodium and chloride ion activities, sodium chloride distribution, osmotic pressure, and viscosity were carried out. The measurements of membrane potential and ionic activities gave consistent results which could be accounted for by the Donnan theory. The second virial coefficient, which was found to be much lower than the ideal Donnan term, was examined according to Scatchard's theory. It was found that while the theory gave a good qualitative explanation to the experimental results, it could not be used for quantitative discussion. For quantitative examination of the experimental second virial coefficient, the value of second virial coefficient was calculated from the assumption that osmotic pressure is proportional to the difference of the sum of solute activities on both sides of membrane, and was found to be nearly equal to the observed value.
The kinetics of radical polymerization of ethylene. I. General kinetics
Authors: Laita Z. 
Published: April 2003

AbstractPhotosensitized polymerization of ethylene in benzene solution has been studied at 83°C. using azoisopropane as initiator. Experiments were conducted in the concentration range from 6.5 to 28.1 wt.‐% of ethylene and at pressures equal to the vapor pressure of the solutions. The apparent order of reaction with respect to the monomer varies from 1 to 1.5. The intensity exponent exceeds 0.5 and increases with increasing initiator concentration. Chain transfer constants with monomer, solvent, and initiator have been determined. Their values are: k4/k2 = 5 x 10−4, ks/k2 = 2 x 10−3, and kK/k2 = 0.5 ± 0.1, respectively.
Endgroups in tetrafluoroethylene polymers
Authors: Bro M. I. , Sperati C. A. 
Published: April 2003

AbstractThe aqueous polymerization of tetrafluoroethylene initiated with ammonium persulfate in neutral or relatively weak acid solutions leads to polymer containing carboxyl end groups. The conversion of this endgroup to the sodium salt and its pyrolysis to the terminal olefin was followed, using infrared absorption technique.
A theory of the thermodynamic behavior of non‐electrolyte solutions
Authors: Maron Samuel H. 
Published: April 2003

AbstractA nonstatistical theory has been developed to account for the heat, entropy, and free energy changes accompanying the formation of binary non‐electrolyte solutions, and for associated thermodynamic properties such as activities, activity coefficients, osmotic pressures, and light‐scattering behavior. The theory considers the volume changes occurring during solution, the effective volume occupied by the molecules, their relative size, and their interactions as a function of temperature and concentration. Since the approach was general in character, the theory should be applicable to polymer solutions as well as to solutions of low molecular weight substances.
Molecular weight distributions for polydisperse systems
Authors: Schumaker Verne N. 
Published: April 2003

AbstractIn this communication, equations are developed which allow the calculation of well defined average molecular weights and molecular weight distributions for unfractionated polydisperse polymer systems by appropriate combinations of the results of sedimentation, viscosity, and diffusion measurements. This theoretical approach is based upon the existence, for the polymer‐solvent system being studied, of a simple equation relating molecular weight to sedimentation coefficient. The particular equation chosen in this communication is the relation M = ASγ where M and S are the molecular weight and the sedimentation coefficient, respectively, and A and γ are constants for polymer‐solvent system being studied. The equations developed show how the constants A and γ may be determined from measurement of other hydrodynamic properties such as the diffusion coefficient and the intrinsic viscosity of the unfractionated system. Systems which are homogeneous with respect to molecular weight but polydisperse in shape are also considered, and equations are developed for determining the molecular weight of such preparations. Finally, systems polydisperse both with respect to shape and molecular weight are examined, and a possible method for the molecular weight characterization of such systems is presented.
The polymerization of acrylamide initiated by ceric nitrate‐3‐chloro‐1‐propanol redox systems
Authors: Mino G. , Kaizerman S. , Rasmussen E. 
Published: April 2003

AbstractThe polymerization of acrylamide initiated by ceric nitrate and 3‐chloro‐1‐propanol was studied in aqueous solution at 25°C. At constant hydrogen ion and nitrate ion concentration, the rate of polymerization was found to be independent of the ceric ion concentration. The molecular weight of the polymer was very low. To explain the data, a kinetic scheme is proposed whereby ceric ions are responsible for both initiation and termination. The rate constant for oxidative termination was found to be of the order of 105 l. mole−1 sec.−1 and varied with the hydrogen ion and the nitrate ion concentrations.
Triazines. XX.1s‐triazine as a new co‐reactant in polymer synthesis
Authors: Grundmann Christoph , Kreutzberger Alfred 
Published: April 2003

AbstractTrimeric hydrogen cyanide, the structure of which has recently been established as striazine, exhibits as most characteristic phenomenon a marked readiness to undergo ring cleavage upon the action of nucleophilic reagents. This susceptibility to ring cleavage makes s‐triazine an important source for methine (CH) groups by means of which other functional groups can be linked each other. Advantage has been taken of the methinylation capability of s‐triazine to link the functional groups in diamines. While the lower members of the aliphatic diamine series, i.e., ethylenediamine and 1,3‐propanediamine, react With s‐triazine to give cyclic compounds, higher diamine homologs like 1,5‐pentanediamine and 1,6‐hexanediamine furnish exclusively open chain polymers termed polyamidines. 1,4‐Butanediamine, being on the verge of these two diamine categories, forms both the cyclic compound and the open chain polymer. In the polyamidine synthesis, the successful isolation of intermediates furnishes an informative picture of the mode of formation. In view of the fact that other functional groups, e.g., SH, NHNH2, and OH, are amenable to this reaction also, s‐triazine may be considered as a novel important starting material for new types of chain‐like polymers containing hetero atoms.
Adsorption of polymers: Polystyrene on carbon
Authors: Frisch H. L. , Hellman M. Y. , Lundberg J. L. 
Published: April 2003

AbstractThe adsorption of polystyrene from toluene solution on a carbon black has been studied at 25°C. under varying conditions of dryness. The isotherm for adsorption on the relatively dry carbon black exhibited a characteristic steep initial rise as a function of concentration and attained a saturation value. Larger molecules appear from intrinsic viscosity studies to be adsorbed preferentially. The rate of desorption appears to be so low that, for time periods of the order of two weeks, the adsorption of polystyrene is effectively irreversible. The total adsorption of polymer is decreased by extreme drying and by saturating the system with water.
The kinetics of radical polymerization of ethylene. II. Determination of the kinetic coefficients
Authors: Laita Z. , Macháček Z. 
Published: April 2003

AbstractBy the method of intermittent illumination, the kinetic coefficients for monoradical termination, mutual termination, and propagation at 83°C. have been evaluated. It has been found that monoradical termination is caused by azoisopropane only. The rate of initiation has been determined both by the molecular weight method and by the inhibitor technique. From the comparison of results, it follows that the predominating termination reaction is disproportionation. The values of the kinetic coefficients are:

Propagation
k2 = (4.7 ± 0.3) × 102 1./mole‐sec.

mutual termination
k3 = (1.05 ± 0.05) × 109 1./mole‐sec.

monoradical termination
k5 = l.85 × 102 1./mole‐sec.

transfer with monomer
k4 = 0.25 l./mole‐sec.

transfer with benzene
kS = 1.0 l./mole‐sec.
The infrared spectrum of polyethylene terephthalate. I The effect of crystallization
Authors: Miyake Akihisa 
Published: April 2003

AbstractFilms of amorphous polyethylene terephthala were drawn and heated to various extents. Intensity change of the infrared spectral bands resulting from these treatments were followed. There are more than seven bands which change their intensities by drawing, and sixteen bands affected by heat treatment. Exactly the same changes are also observed in several aromatic esters of ethylene glycol. The bands that intensify in the crystalline state of these model compounds correspond to the crystalline bands of polyethylene terephthalate, and the bands that appear in the melt of model compounds correspond to the amorphous bands of polyethylene terephthalate. Main crystalline bands and all of the amorphous bands are associated with ethylene glycol residue. A crystalline band makes a couple with one of the amorphous bands and the frequencies of this couple have reasonable values as the characteristic vibration of the ethylene glycol residue. Thus, the spectral change can be interpreted by the rotational isomerism of the ethylene glycol residue, the gauche form in the amorphous part changing into the trans form by crystallization. The crystalline band at 973 cm. −1 corresponds to the Bu type CO stretching vibration of the trans form, and the amorphous bands at 1099 and 1042 cm.−1 correspond to A and B type CO stretching vibrations of the gauche form. The crystalline bands at 1475, 1387, and 988 cm. −1 are considered to be manifestations of the perturbation of the crystal field.
The infrared spectrum of polutrthylene terephthalate. II. Polyethylene‐d4 terephthalate
Authors: Miyake Akihisa 
Published: April 2003

AbstractPolyethylene‐d4 terephthalate was prepared from dimethyl terephthalate and 1,2ethane‐d4‐diol. This polymer also showed spectral changes by drawing and heattreatment as in the case of polyethylene terephthalate. Comparison of the deuterated polymer spectrum with that of ordinary polymer, reveals the bands associated with ethylene glycol residue quite clearly. Almost all the bands which change their intensities by crystallization, belong to ethylene glycol residue vibration. From the shifts on deuteration, the bands of polyethylene terephthalate at 1101, 1042, and 973 cm.−1 are assigned to C‐O vibrations. Vibrational frequencies associated to terephthalic acid residue remain unchanged on deuteration of the ethylene glycol residue. Assignments for p‐substituted benzene residue are given, based on the assignments of benzene, p‐benzene‐d2, p‐xylene, etc. The bands at 873 and 727 cm.−1 are both assigned to the coupled vibrations of aromatic out‐of‐plane CH bending mode and out‐of‐plane OCO bending mode. These two modes seem to have a considerable interaction with each other in aromatic esters.
Conformation of linear chains and their mode of packing in the crystal state
Authors: Natta Giulio , Corradini Paolo 
Published: April 2003

AbstractSome general rules regarding the conformation and mode of packing of macromolecular chains in crystals are illustrated. The monomeric units occupy equivalent positions in regard to the axis of the chain. It follows that crystallizable polymers must have a type of regularity which will enable them to assume the helix‐ or glide‐plane conformation. Energy considerations lead to other rules regarding the conformation and the mode of packing of the chains. Isosterism phenomena leading to statistical substitution of chains in the lattice and to the existence of planes, along which the macromolecules pack preferentially are considered. The structures of isotactic and syndiotactic polymers, and of all four stereoisomeric polybutadienes are discussed.
The relations between intrinsic viscosity and molecular weight for partially alcoholized polyvinyl acetates
Authors: Beresniewicz A. 
Published: April 2003

AbstractViscosities of partially alcoholized polyvinyl acetates were measured at 25°C. using water as solvent. The intrinsic viscosity decreases, whereas the Huggins constant, k′, increases with increasing fraction of nonalcoholized acetate groups in the polymer. A plot of the viscosity of a 4.0% solution against the degree of alcoholysis exhibits a minimum approximately at 87% alcoholysis. The following equation was established, which expresses the intrinsic viscosity of partially alcoholized polyvinyl acetate as a function of the fraction of alcoholized acetate groups, α, and of the molecular weight:

It is shown that in partially alcoholized polyvinyl acetate the larger molecules are somewhat more completely alcoholized than the smaller ones. The resulting heterogeneity with respect to the degree of alcoholysis affects the efficiency of fractionation of such a polymer with respect to its chain length.
Investigations on banded spherulites
Authors: Keller A. 
Published: April 2003

AbstractThe nature of banded spherulites was further investigated. The principal material used was a polyester, namely, polytrimethylene glutarate, but use was made also of nonpolymeric materials. A variety of observations on extinction effects with the Universal Stage conclusively confirmed the twisted crystal model of banded spherulites. It is shown that banding observed in the form of other than extinction effects need not indicate a zone structure. Such bands can be due to diffraction effects or pseudopleochroism following from the twisted structure, examples of such effects being quoted. In some cases, genuine rhythmic distribution of matter was observed, and it is shown that these effects arise in two‐dimensional spherulites only, and can still follow from the twisted morphology under the influence of a substrate. Direct observations of a helicoidal morphology are also quoted.
Thermal degradation of polymethacrylonitrile. Part V. The mechanism of the initiation step in coloration reactions
Authors: Grassie N. , McNeill I. C. 
Published: April 2003

AbstractThe coloration reaction of polymethacrylonitrile, which involves linking up of adjacent nitrile units, has previously been shown to be initiated by traces of methacrylic acid present in the polymer chains. It also occurs when pure polymer is heated with small quantities of a wide variety of substances including carboxylic acids, phenols, imides, and aliphatic amines. The carboxylic acid initiated reaction exhibits first order kinetics. The rates of initiation by a number of aromatic acids have been measured and compared with the pKa values. The initiating power is strongly influenced by the nature of substituents in the acid molecule, weaker acids giving a higher rate of initiation. A semiquantitative treatment has been applied to phenols with similar results. A mechanism for the initiation step in the color reaction is presented involving nucleophilic attack on a nitrile group. This is consistent with the results obtained for acids and phenols, and the observations of other workers on the alkali‐induced coloration in solution are explained similarly. It is noted that all the substances capable of acting as initiators are Lewis bases.
The kinetics of polymerization of α‐vinylnaphthalene
Authors: Loshaek S. , Broderick Edward , Bernstein Philip 
Published: April 2003

AbstractThe kinetics of the 2,2′‐azobisisobutyronitrile (AIBN)‐initiated bulk polymerization of α‐vinylnaphthalene (AVN) at 50, 60, and 70°C. is reported. The polymerization rate is proportional to the 1/2 power of the initiator concentration and the first power of the monomer concentration, and the ratio of the termination rate constant to the square of the propagation rate constant is slightly less than for styrene. Unlike styrene, however, very low molecular weight polymers (ca. 2000–6000) are obtained throughout the entire conversion of monomer to polymer. The molecular weight is shown to be controlled by a chain transfer reaction with the monomer, the value of the transfer constant being about 0.03 at 50, 60, and 70°C., about 300 times that of the monomer transfer constant for styrene. The transfer reaction is attributed to an attack of a growing polymer radical on the naphthalene ring of the AVN. In support of this, the transfer constant of the polystyryl radical with naphthalene was also found to be large (1.1 × 10−3), about 600 times that of the transfer constant (1.86 × 10−6 at 60°C.) of the same radical with benzene. A transfer constant of similar magnitude was obtained for the polynaphthalyl radical with naphthalene. This greater polystyryl radical affinity for naphthalene over benzene is in excellent agreement with expectations based on methyl radical affinities for these same substrates. The greater value of the monomer transfer constant of AVN over that of the polynaphthalyl or polystyryl radicals with naphthalene suggests an activation of the naphthalene ring in AVN. The differences in the polymerization kinetics of AVN and vinyl benzoate are discussed. The overall second‐order thermal rate constant for AVN is found to be about eight times that for styrene at the same temperature. Overall activation energies of 21.5 and 17.4 kcal./mole are obtained for the initiated and purely thermal polymerizations, respectively. An empirical intrinsic viscosity‐molecular weight relation for AVN polymer is given.
Reactivity ratios and rates in the copolymerization of α‐vinylnaphthalene and styrene
Authors: Loshaek S. , Broderick Edward 
Published: April 2003

AbstractCopolymerization reactivity ratios at 60°C. for α‐vinylnaphthalene (AVN) and styrene are found to be r1 = 1.35 and r2 = 0.67, respectively, from which Price Q and e values for AVN of 1.15 and 0.49 are calculated. From these Q and e values and those published previously for 4‐chloro‐1‐vinylnaphthalene, styrene, and p‐chlorostyrene it is shown that the chlorine atom has a very similar electronegative effect in both the styrene and AVN rings. Initial rates of copolymerization at 60°C. with 2,2′‐azobisisobutyronitrile as initiator were determined over the entire composition range from pure AVN to pure styrene. The rate data are shown to be consistent with a value of 3 for ϕ, the cross‐termination rate constant.
Stereoregulated polymerization in the free propagating species. II. Effect of monomer structure on the polymerization of vinyl esters
Authors: Fordham J. W. L. , McCain G. H. , Alexander L. E. 
Published: April 2003

AbstractThe first paper of the series contained the theoretical prediction that syndiotactic propagation could be favored over isotactic propagation in free radical polymerization by the nature of the monomer substituent group. To check this hypothesis the steric structure of polymers of vinyl acetate and certain haloacetates was investigated. X‐ray examination of the polyvinyl esters and the solubility of derived alcohol polymers indicate that the degree of regularity increases in the order: acetate < monochloroacetate < polychloroacetates < trifluoroacetate. The influence of the substituent group is limited in the polyvinyl esters because only the trifluoroacetate shows true crystallinity, and, even in this polymer, the average length of the regular sequences appears to be small. The above order of regularity suggests that the electrostatic factor is more important than the steric factor in the stereoregulated polymerization of vinyl esters. The regular sequences of the trifluoroacetate are indicated to have a syndiotactic configuration from the chain repeat distance. The polymerization of the ester is believed to involve predominantly syndiotactic propagation, with relatively frequent interruptions of isotactic propagation. The generalizations agree with results reported for other stereoregular radical polymerizations. Conceivably, syndiotactic propagation may be preferred for free radical polymerization in general, and polymers produced under radical conditions may be more regular than has been realized.
Studies on the low pressure polymerization of ethylene by use of catalysts containing potassium alkyls
Authors: Zilkha Albert , Ottolenghi Ariel , Frankel Max 
Published: April 2003

AbstractThe low pressure polymerization of ethylene by use of catalysts prepared from either butyl or amyl potassium, or the reaction product of potassium with chlorobenzene and titanium tetrachloride was studied. The efficiency of the catalysts depended on the molar ratio of the potassium alkyl to titanium tetrachloride but was in every case considerably lower than that of the corresponding lithium or sodium alkyl containing catalysts. Optimum molar ratios of the butyl potassium–titanium tetrachloride catalysts were between 2.8 to 6.1 with sharp drops on both sides of the optimum; for the amyl potassium between 1.1 to 3.7. The reaction product of potassium with chlorobenzene yielded much weaker catalysts with titanium tetrachloride, and the properties of the polymers obtained were different. The physical properties of the polyethylenes obtained, as determined from x‐ray diffraction diagrams, infrared spectra, and from melting points, showed similarity to those obtained with the lower alkali metal catalysts. The lower activity of the potassium catalysts may be related to the large ionic radius of the potassium, which influences the properties of the catalyst complex formed with titanium tetrachloride. Propylene did not undergo polymerization with the potassium alkyl containing catalysts at low pressure.
Molecular weight dependence of intrinsic viscosity, diffusion constant, and second viral coefficient of polyacrylonitrile
Authors: Kobayashi Hidehiko 
Published: April 2003

AbstractCareful intrinsic viscosity and diffusion constant measurements are reported for nine fractions of polyacrylonitrile prepared by repeated refractionation. For a molecular weight range of from 28,000 to 575,000, relationships are obtained between second virial coefficient, diffusion constant, or intrinsic viscosity in dimethylformamide at 35°C., and absolute molecular weight. These relationships are represented by the equations:

and

where the units of intrinsic viscosity are 100 ml./g. An explanation is offered for the difference between the viscosity equation and other similar equations in the literature, as well as for the discrepancies among the various equations in the literature. Empirical plots of kD vs. [η] are presented, giving lines which are straight within the limits of accuracy of the data. From these results, the following relation was obtained: c = 1 − α, where α is the exponent in [η] = KIMα, and c is the exponent in A2 = KIIIM−c.
Single‐point determination of viscosity
Authors: Poláček J. 
Published: April 2003

AbstractIntrinsic viscosities of benzene solutions of fresh, naturally, and artificially aged Svitprene K polychloroprene and their fractions were calculated by using Hart's method for the single‐point determination of intrinsic viscosities. It was found that this quick method was sufficiently precise for Svitprene K. In most cases the deviations of the calculated values from those obtained by extrapolation according to the equation of Schulz and Blaschke were lower than 1% of intrinsic viscosity.