bluuebunny/crossref_metadata_2025_split huggingface dataset:
The action of sodium salicylate and related compounds on the proteins of the groundnut (Arachis hypogaea)
Authors: Naismith W. E. F. 
Published: April 2003

AbstractThe action of sodium salicylate on arachin and conarachin II has been investigated by viscosity and sedimentation velocity techniques. Considerable evidence for the occurrence of aggregation of the protein has been obtained. It appears that the salicylate ion first penetrates the protein molecule causing a modification of the internal linkages resulting in an opening up of the molecule. This would lead to the exposure of many more active groups which probably then react with active groups on other molecules. The effect of the salicylate ion was more pronounced at lower pH values (ca. 6‐7) and higher ionic strengths (ca. 1.0). Considerably greater effects were observed with conarachin II than with arachin, indicating that the arachin molecule is probably more strongl bound internally. The effect of a number of other sodium salts of organic acids on conarachin II was examined, and it appears that the action of any organic anion depends on the nonpolar portion of the molecule as well as on the polar groups.
Vinyl pinonate‐vinyl chloride copolymers
Authors: Marvel C. S. , Vessel Eugene D. , Magne F. C. 
Published: April 2003

AbstractA homopolymer of vinyl pinonate and copolymers of vinyl pinonate and vinyl chloride have been described. The copolymer containing 19.8% of vinyl pinonate seems to show the best all around properties as a rigid plastic. The presence of vinyl pinonate as a component of the copolymer does not give a plasticized film. The homopolymer of vinyl pinonate exhibits adhesive characteristics. The use of an external plasticizer, di‐2‐ethylhexyl phthalate, with these compositions is not very promising.
Radiochemical studies of free‐radical vinyl polymerizations. Part II. The polymerization of vinyl monomers in the presence of polyisoprenes: Use of C14‐labeled initiators to determine the mechanism of graft‐interpolymer formation
Authors: Allen P. W. , Ayrey G. , Moore C. G. , Scanlan J. 
Published: April 2003

AbstractPolymerization of methyl methacrylate at 60°C. by benzoyl peroxide in benzene solutions of polyisoprenes (e.g., natural rubber and gutta‐percha) yields polymethyl methacrylate and a graft interpolymer having polymethyl methacrylate side chains attached to the polyisoprene backbone. Use of azobisisobutyronitrile (AZBN) as initiator in comparable systems gives free polymethyl methacrylate, but no graft interpolymer. The cause of this specific initiator effect, and the mechanism of graft polymerization have been determined by using C14‐labeled initiators. Benzoyl peroxide initiates graft polymerization by prior reaction of the derived phenyl and benzoyloxy radicals with the polyisoprene by addition to the double bond, and by abstracting α‐methylenic hydrogen atoms to give polyisoprenic alkyl and alkenyl radicals, respectively, which act as loci for methyl methacrylate polymerization. In the system gutta‐percha‐methyl methacrylate, at 60°C., 35–45% of the grafted vinyl polymer side chains are initiated by hydrogen abstraction, and about 90% of the initiator radicals undergoing addition to the double bond are benzoyloxy. The modes of termination of the grafted and free polymethyl methacrylate radicals have been evaluated semiquantitatively, and it is found that, in the graft interpolymer, 13–27% of the polymethyl methacrylate chains have both ends attached to gutta‐percha chains (i.e., have an “I” structure), while 73–87% are attached at one end only to gutta‐percha chains (i.e., are “T” structures). The reliability of the separatory procedure previously devised8 to resolve the bulk polymer obtained in the graft‐polymerization system has now been verified by use of the isotopedilution technique. The inability of AZBN to initiate graft polymerization is attributed to the markedly inferior capacity of the resonance‐stabilized Me2Ċ(CN) radicals, relative to C6H5· and C6H5COO·, to engage in double bond addition and hydrogen abstraction reactions.
cis‐trans Isomerization in polyisoprenes. Part I. Improvement of the low temperature properties of natural rubber by reaction with thiol acids in solution and in latex
Authors: Cunneen J. I. , Shipley F. W. 
Published: April 2003

AbstractNatural rubber is converted by reaction with a small amount of a thiol acid into a modified rubber which crystallizes at low temperatures much more slowly than the original rubber. This change in rate of crystallization is probably due to the conversion of some of the cis double bonds in natural rubber into the trans configuration. The preparation of the modified rubber from latex and its physical properties are described in detail.
Rheology of polyisobutylene. III. Elastic recovery, non‐Newtonian flow, and molecular weight distribution
Authors: Leaderman Herbert , Smith Robert G. , Williams L. C. 
Published: April 2003

AbstractMoments of the molecular weight distribution have been measured in the equilibrium ultracentrifuge under ideal conditions for two rough fractions of polyisobutylene (Mw 1.6 × 104 and 1.31 × 105). Flow and elastic recovery measurements were made on these materials and on a series of blends; the non‐Newtonian flow at small shear stresses was characterized by the reciprocal of the Ferry “internal shear modulus,” Gi, and the magnitude of the elastic recovery by the steady‐state elastic compliance, Je. This was found to be about two to three times the magnitude of 1/Gi. Measured values of Mz+1 for the fractions appeared unreasonably high compared to values obtained by assuming a Lansing‐Kraemer distribution. With either set of values of Mz+1 for the fractions, it was found that Je was proportional to the square of (MzMz+1/Mw) for these materials, in disagreement with the results of molecular theories, which predict proportionality with the first power of this function.
Copolymerization characteristics of pentachlorophenyl vinyl sulfide
Authors: Holly E. D. 
Published: April 2003

AbstractPentachlorophenyl vinyl sulfide was prepared by vinylation of pentachlorothiophenol in aqueous buffers. The preparation of pentachlorophenyl vinyl sulfoxide and of ar‐tetrachloro‐ar‐(vinylthio)benzenethiol are described. The copolymerization of pentachlorophenyl vinyl sulfide with styrene and with methyl acrylate was studied. The monomer reactivity constants of pentachlorophenyl vinyl sulfide (Q = 0.23, e = −0.6) indicate less resonance stabilization of the radical and less electron density in the vinyl group than is the case with phenyl vinyl sulfide or methyl vinyl sulfide.
Estimation of the parameters in the Mark‐Houwink equation
Authors: Voeks J. F. 
Published: April 2003

AbstractA method is given for estimating the parameters K and β in the so‐called Mark‐Houwink equation

from measurements of molecular weight, intrinsic viscosity and second virial coefficient of a single polymer sample. Although the treatment is based on existing theories, certain approximations and its connection with the empirical Mark‐Houwink equation reduce it to semi‐empiricism. The method is restricted to linear polymers. Examples drawn from the literature are used to test the method.
Molecular weight distribution of polystyrene by sedimentation velocity analysis
Authors: McCormick Herbert W. 
Published: April 2003

AbstractAnalysis of sedimentation velocity experiments employing a θ solvent has been applied to measure the molecular weight distribution of both broad‐ and narrow‐distribution polystyrene. The θ solvent was found necessary for satisfactory results. The required sedimentation constant‐molecular weight relationship was obtained from both intrinsic viscosity data and molecular weights obtained by Archibald's method.
Quaternary ammonium salt as initiator for vinyl polymerization
Authors: Fueno Takayuki , Okamoto Hiroshi , Tsuruta Teiji , Furukawa Junji 
Published: April 2003

AbstractBinary mixtures of amines and alkyl (or aralkyl) chlorides were used as the initiators for the polymerizations of several acrylic monomers and styrene. A parallelism was found between the catalytic actions of the mixtures and their quaternary salt formations. Comparative experiments showed that the preformed quaternary ammonium salts were superior catalysts to the corresponding binary mixtures. The inhibitory action of hydroquinone on the polymerization and the composition of a copolymer of methyl methacrylate and styrene suggested that the vinyl polymerizations initiated by ammonium salts were free radical reactions. An equimolar mixture of benzyl chloride and N,N‐dimethylaniline gave, when refluxed for ten hours, N‐methyl‐N‐benzylaniline and N,N‐dibenzylaniline. Thus, it was suggested that the binary mixtures would first form the ammonium salts, followed by decomposition to give a radical which initiated the radical polymerizations of vinyl monomers.
Proton magnetic resonance study in high polymers
Authors: Jain P. L. 
Published: April 2003

AbstractProton magnetic resonance absorption has been studied in uncured as well as in heataged cured samples of high polymers: epoxy‐resin‐modified polyester‐amide (Bondar), polyvinyl acetal (Formvar), glycol‐glycerol terephthalate (Isonel), and Terebec. The resonance absorption line in the uncured stage of all the above compounds is very complex; in the cured stage, however, it consists of a broad line with a narrow line superposed on it. It has been shown that this technique is very useful for determining the uncured material remaining at any stage during the curing process. Also it is indicated that the aging of the polymeric material at high temperature is the result of two processes, crosslinking and scission of the molecules, which take place simultaneously.
Nitrocarboxymethyl cellulose
Authors: Haas Howard C. , Schuler Norman W. 
Published: April 2003

AbstractMethods for nitrating carboxymethylcellulose were investigated. The best results were obtained with the use of 90% nitric acid‐phosphorus pentoxide mixtures. Two commercial carboxymethylcelluloses containing 0.7 and 1.2 carboxymethyl groups per anhydroglucose unit were employed in the nitration studies. Analyses, viscosities, infrared spectra, and solubilities of the nitrocarboxymethyl celluloses are reported.
Gamma radiation‐induced solution polymerization of ethylene
Authors: Henley Ernest J. , Ng C. Chong 
Published: April 2003

AbstractGamma radiation‐initiated polymerization of ethylene in solution has been studied by measuring the pressure decrease with dose in a batch system. Water, ethanol, benzene, and carbon tetrachloride were used as solvents. The radiation intensity was 134,000 rep/hr. G values and number‐average molecular weights were obtained from runs made at room temperature and at initial pressures of 5 to 13 atmospheres. The solvent radical yields and chain transfer constants for these systems were calculated from an expression derived on the assumption of a free radical mechanism with bimolecular termination.
Study of entanglement of polymers in solution by viscosity measurements
Authors: Maron Samuel H. , Nakajima Nobuyuki , Krieger Irvin M. 
Published: April 2003

AbstractA study has been made of the flow behavior of solutions of a single sample of polystyrene in five different solvents in both the Newtonian and non‐Newtonian regions. The concentration range covered was approximately 0‐20% by weight, and the temperatures were 20, 30, 40, and 50°C. By application of the Ree‐Eyring theory it was found possible to represent the observed data in terms of two flow units, and to obtain from the parameters of the Ree‐Eyring equation the effective hydrodynamic volume occupied by the polymer in solution, εv, where v is the volume fraction of polymer and ε an effective volume factor. For any given solvent ε varies from [η]/2 at v = 0 to ε = ca. 4 at v∞, the volume fraction at which εv = 1 and the viscosity becomes infinite; and, except in very dilute solutions, ε is essentially independent of the temperature. Again, for any given value of v, ε is a function of the nature of the solvent only between v = 0 and v = 0.04. Above the latter concentration ε is completely independent of the solvent in which the polystyrene is dissolved, and becomes merely a function of the solution concentration. These results indicate that chain entanglement in solution, if it does occur, can take place only below a concentration of v = 0.04. Above v = 0.04 no entanglement can be present, and the configuration of the polymer chain, as reflected in the effective volume they occupy, is governed only by the nonspecific factor of the space available for occupancy by each molecule. As this space decreases with increase in concentration, the polymer molecule is forced to reduce its effective volume by coiling into a tighter mass. This process continues until εv becomes equal to unity, at which point the state of tightest coiling is reached without change in the nature of the flow. In the latter state the polymer molecule is shown to occupy a volume 2 to 3 times, and to have a cross section 1.26 to 1.44 times, that of the polymer in bulk.
Bulk viscosity of polymeric systems
Authors: Hirai Nishio , Eyring Henry 
Published: April 2003

AbstractThe theory of bulk viscosity as developed for the liquid state was applied to amorphous high polymeric systems. The isothermal volume contraction, the dependence of shear viscosity, and the fictive temperature of quenched high polymeric substances are all related to the bulk viscosity and explained by this theory. Simple representations are given for compressibility, bulk modulus, shear modulus, thermal expansion coefficient, and heat capacity, all of which are necessary to discuss the bulk viscosity. The theory has been compared with the experimental results for natural rubber, polystyrene, polyisobutylene, and polyester.
The structure of high polymer spherulites
Authors: Price Fraser P. 
Published: April 2003

AbstractThe spherulitic structures in very thin films of linear plolyethylene and poly‐oxa‐1,4‐bis(dimethylsilylene) benzene have been examined by a variety of optical techniques. These techniques included bright field electron microscopy and bright and dark field light microscopy. Polarization effects in these polymers were also examined using the light microscope. The polarization phenomena were most marked in the poly‐oxa‐1,4‐bis(dimethylsilylene) benzene, presumably as a result of the benzene ring. The negative polyethylene spherulites showed a banded structure in all types of illumination. It was shown that the banded structure exhibited between crossed Nicols is due to low positive birefringence while the black cross was due to zero amplitude effects. All the optical phenomena could be interpreted in terms of a model which proposes that a given spherulite radius is coposed of a stack of crystallites whose refractive index ellipsoids (a) have centers along the radius, (b) have optic axes which make a fixed angle with the spherulite radius, and (c) are twisted as they go out along the radius so that the displacement is proportional to the twist. The model also emphasizes the presence of interstitial amorphous polymer. On the basis of this model the crystallites in polyethylene spherulites were shown to have a twist length of about 4 μ and to have their major refractive index axes (chain directions) inclined at an angle of 75° to the spherulite radius.
Molecular distributions in polycondensations involving unlike reactants. IV. Intra‐branch distributions arising in the crosslinking of perfect networks
Authors: Case L. C. 
Published: April 2003

AbstractVaroius types of condensation polymerization systems are considered which yield perfect networks (no unattaced chain ends). The distributions of chain lengths between branch points and the branching functionality are considered. Three systems are considered in datail:

Simple Gelation Systems.
Systems coupled prior to crosslinking.

Infinitely long coupled chains.
Finite‐length coupled chains.

It is shown that most of the chain length distributions are nearly geometrical. Two exceptions are noted, systems involving Poisson‐distribution prepolymer, and those involving very unsymmetrical reactants. It is noted that the branching functionality is quite different in the three systems, with systems II‐B giving essentially uniform trifunctional branching. Examples of physically realizable systems which correspond to the theoretical models are briefly noted and discussed.
Sorption of water vapor by cellulose and polymers at high humidities
Authors: Kawai Tōru 
Published: April 2003

AbstractSorption of water by cellulose and other polymers at high humidities is treated as a process of solution of water into the disordered regions of the polymer with deviation from the simple solution theory because of restrications on the swelling of the system by the insoluble ordered regions. The viewpoint taken in this paper is based on the principles presented by Rowen and Simha, but some improvement has been made in the following point. (1) In view of oversimplification made by them in evaluating the partial molal free energy change ΔF̄1(el) due to the elastic deformation of the polymer in the course of sorption, the equation obtained for the swelling of crosslinked polymers is employed: ΔF̄1(el) = RT(1/z)v21/3, where z is the ratio of the molal volume of the polymer between crosslinks to that to solvent, and v2 is the volume fraction of the polymer. (2) Since the solution of water is considered to take place only into the disordered regions, the volume fraction of the polymer in the amorphous regions must be taken for v2 in the expression of the sorption isotherm, whereas the existence of crystalline regions has been virtually ignored in the treatment of Rowen and Simha. (3) In examining the sorption data by the solution theory, one must be careful of possible deviations due to the variation of the interaction parameter with polymer concentration, although the present analysis of the sorption isotherm remains unsatisfactory in this point. Along this line of argument, the sorption data for several cellulosic materials and polyvinyl alcohol were examined. The most important feature brought out in this work is the fact that the elastic contribution to the isotherm is considerably great, although recent treatments of sorption by the solution theory have neglected it. Unexpectedly, very small values were obtained for z. This would be an indication that junction points between molecules are present in the solution of amorphous cellulose and that these restrict the swelling of the sample to a great extent. The simple solution theory does not explain the experimental evidence examined here and leads to unreasonably high values for the interaction parameter μ. This is also true for polyvinyl alcohol fibers, but in this case μ diminishes as the vapor pressure increases in the highhumidity region, contrary to the usual case for a number of polymer‐water systems. This anomalous tendency may be accounted for by a hypothesis that the progressive swelling of the fiber would break the hydrogen bonds between the polymer molecules in the sorpation process.
Photochemistry of cellulose acetate
Authors: Jortner J. 
Published: April 2003

AbstractThe photodegradation of cellulose acetate by near ultraviolet light in air was studied. The photochemistry of cellulose acetate is interpreted on the basis of spectrophotometric data. A kinetic equation for the photodegradation process was derived. The effect of light intensity on the photodegration process was investigated. The quantum yield for the chain scission was found to be 2.5 × 10−3. The retarding effect of phenyl salicylate on photodegration was investigated. Under the effect of ultraviolet light phenyl salicylate is converted into a strongly absorbing and nonfluorescent product which acts as an inner filter for ultraviolet light. The kinetic result of degradation in the presence of salicylate and metal oxides can be adequately represented by the kinetic equation. Photodegradation in the presence of α‐phenylnaphthylammie was studied.
Dielectric behavior of copolymers of vinylidene chloride and vinyl chloride
Authors: Saito Shogo , Nakajima Tatsuji 
Published: April 2003

AbstractThe dielectric properties of copolymers of vinylidene chloride and vinyl chloride with various compositions are studies. The dielectric measurements are made over the frequency range 0.1 to 106 cycles/sec. and the temperature range ‐23 to 84°C. Glass transition temperatures of the copolymers are determined by a dielectric method which is based on the temperature desendence of the magnitude of the dielectric dispersion. The larger the content of vinylidene chloride, the lower is the glass transition temperature. Effect of cooling speed on the magnitude of the dispersion is investigated. From the dielectric point of view, as a concequence, the glass transition seems to imply any essential transition in addition to an apparent relaxation phenomena. Energyof activation for the relaxation prosess depends upon the temperature and becomes maximum at a little higher temperature than the glass transition temperature. The temperature where the energy of activation becoms maximum is lowered when the sample is cooled more slowly. Cole‐Cole's prameter relating the distribution of relaxation times is constant below the glass transition temperature and increases linearly with temperature above the glass transition temperature and seems to become unity at the melting temperature. This result coincides with that for the parameter of polychlorotrifluoroethylene.
The kinetics of graft copolymerization
Authors: Cooper W. , Vaughan G. 
Published: April 2003

AbstractGamma‐ radiation induced graft copolymerization of methyl methacrylate with natural rubber is characterized by high yields of grafted polymer even at relatively high monomer concentrations. The rates are first order except at low monomer concentrations; above 95% rubber concentration the polymerization rates are very low. A reaction mechanism has heen proposed in which it is shown that these results are consistent with a relatively slow initiation step between rubber radicals and methyl methacrylate and a rapid crossed termination reaction between methacrylate radicals and rubber radicals. In order to explain the high yield of grafted polymer, it has been assumed that radicals produced from methyl methacrylate by gamma‐radiation are, unlike the growing methacrylate chains, capable of attacking the rubber molecule and thus from sites for grafting to occur, and also that monomer transfer is negligeable.
Infrared spectrum of polyvinylidene chloride. I
Authors: Narita S. , Ichinohe S. , Enomoto S. 
Published: April 2003

AbstractIn order to assign the infrared spectrum of polyvinylidene chloride, we studied the properties of the bands in the spectrum of this polymer and the spectrum of polyvinylidene bromide. We found that many bands disappeared or became weak in the region of 400 to 700 cm.−1, when polyvinylidene chloride was molten. From the relation between the absorption intesities and the density of the polymer, we could prove that the two bands at 753 and 884 cm.−1 are crystallization‐sensitive bands. The doubt at 1046 and 1071 cm.−1 in the spectrum of polyvinylidene chloride showed an interesting behavior, i.e., one component at 1046 cm.−1 appeared more strongly than the other at 1071 cm.−1 in the spectrum of the unstretched sample, and their intensity relation was inversed by stretching the sample. The infrared spectrum of polyvinylidene bromide resembled very well to the spectrum of polyvinylidene chloride. We assigned several bands in the spectrum of polyvinylidene chloride from their polarizations and spectral regions, i.e., the doublet at 1046 and 1071 cm.−1 is assigned to the skeletal stretching mode, the parallel brand at 1357 cm.−1 to the CH2‐‐wagging mode, the perpendicular band at 1407 cm.−1 to the CH2‐‐bending mode, the band at 2966 cm. −1 to the CH2‐symmetric stretching mode, and the band at 3010 cm.−1 to the CH2‐antisymmetric stretching mode.