bluuebunny/crossref_metadata_2025 huggingface dataset:
Solution properites of dialdehyde starch
Authors: Levine Samuel , Griffin H. L. , Senti F. R.
Published: April 2003

Low levels of periodate oxidation increased the dispersibility of cornstarch in water at 98°C. Above the 10% level of oxidation, cornstarch became more resistant, and longer heating times were generally required to form stable solutions. Light‐scattering, sedimentation, and viscosity measurements showed that the average particle weight in solutions of periodate‐oxidized starches generally decreased with increased level of oxidation and time of heating. Introduction of dialdehyde groups into the anhydroglucose residues of the starch molecules thus made the structure labile toward degradation on heating in water. The experimental results showed, however, that an aggregation reaction also occurred in solutions of oxidized starches. This reaction was most evident at 10% oxidation level, but it was found to occur simultaneously with degradation over a range of oxidation levels. Aggregation probably results from the reaction of aldehyde groups of one molecule with hydroxyl groups of neighboring molecules. The observation that aggregation could be prevented by additon of glucose was explained by competition of hydroxyl groups of glucose with hydroxyl groups of starch in their reaction with aldehyde groups. The angular dependence of the light‐scattering measurements indicated that formation of dumbbell‐shaped particles by crosslinking of near‐spherical particles was probably quite important to the aggregation reaction. Preliminary investigation of periodate‐oxidized waxy maize starch showed that this starch had a much lower average molecular weight in solution than ordinary cornstarch at a comparable level of oxidation. This value may result from the contribution of amylose to the aggregation of ordinary oxystarch.
Studies in the changes in fine structure of cellulosic fibers during mild acid hydrolysis
Authors: Achwal W. B. , Daruwalla E. H. , Nabar G. M. , Subramaniam P.
Published: April 2003

Changes in the accessibility of the fine structure of cellulose as a result of mild acid action on standard cellulose, cellulose mercerized with and without the application of tension, viscose rayon, and cuprammonium rayon have been studied with respect to changes in DP, fiber density, fiber crystallinity, moisture regain, oxidative susceptibility, and equilibrium adsorption of Chrysophenine G, Chlorazol Sky Blue FF, and Procion Brilliant Red 2Bs. Results indicate that the mild acid action on all the cellulosic fibers studied, appears to proceed in three different stages. In the initial stages the acid action is rapid and results in a sudden decrease in DP, moisture region, oxidative susceptibility, and adsorption of dyes with a simultaneous increase in fiber crystallinity and fiber density. The subsequent acid action is slower than that in the initial stages during which the extent of lowering in the values of fiber characteristis is much less, and during the final stages of acid action there is a tendency for the leveling‐off of all the fiber characteristics. The extent of reduction in the values of the fiber properties and the stages during hydrolysis at which the changes take place in different cellulosic fibers depend mainly on the rate of removal of hydrolyzable fraction and the extent of crystallization of cellulose chains taking place during the acid action.
Wandering of crosslinks in rubber at high temperatures
Authors: Voorn M. J. , Hermans J. J.
Published: April 2003

By crosslinking natural rubber in benzene, networks are prepared in which the degree of coiling is higher than normal (“supercoiled” networks). On heating, these networsk are converted to normal ones with the same number of crosslinks but a lower degree of equilibrium swelling. The results of the swelling experiments are in quantitative agreement with theoretical predictions. Results of strees relaxation experiments at elevated temperatures support the conclusion reached on the basis of swelling. It follows that great caution is needed when calculating changes in the density of the crosslinks from changes in stress alone as is sometimes done in kinetic studies.
Enzymatic polymerization. II. Branching by rearrangement and its application to the dextran system
Authors: Bovey F. A.
Published: April 2003

It is shown that increases in molecular weight and branching during the formation of dextran can be qualitatively accounted for by a random rearrangement of initially linear chains. Very large increases of molecular weight can result from the formation of branches at less than 1% of the glucose units of the original chains. The expressions presented do not account rigorously for the actual behavior of the dextran system, probably chiefly because the rearrangement process is no longer random when the molecules have become very large and highly branched.
Enzymatic polymerization. III. The influence of a glucosyl accepto, methyl α‐D‐glucoside, on the molecular weight and kinetics of formation of dextran
Authors: Bovey F. A.
Published: April 2003

The presence of the glucosyl acceptor, methyl α‐D‐glucoside increases the rate of formation of dextran from sucrose, and partially diverts the reaction from production of polymer of very high molecular weight to production of polymer of very low molecular weight. A mechanism to explain this behavior is proposed. It is suggested that, in the absence of an acceptor, high molecular weight polymer is produced by an enzymatic chain reaction. In the presence of acceptor, a nonchain reaction, producing low molecular weight polymer, competes with the chain reaction. This proposal is formulated in detail, and it is shwon that its predictions are in agreement with the observed behavior of the system.
Light scattering of isotactic polystyrene
Authors: Trossarelli Luigi , Campi Ennio , Saini Guido
Published: April 2003

Results of light scattering as well as viscosity measurements on a series of isotactic polystyrene fractions, and on a sample of unfractionated isotactic polymer in toluene at 30°C. are reported. The results are in agreement with the conclusion of Natta, Danusso, and Moraglio that no difference exists between the viscometric behavior of atactic and isotactic polystyrene; the same seems to hold also for the molecular dimensions. The ratio A2M/[η] for isotactic polystyrene is lower than for atactic fractions, and according to the results of Danusso and Moraglio, the second virial coefficient, A2, is probably responsible for the observed difference. The data obtained with the unfractionated sample can be explained in terms of an unusually high M̄w/M̄n ratio.
Copolymerization of N‐vinylurethane
Authors: Ghosez L. , Smets G.
Published: April 2003

N‐Vinylurethane (M1), prepared by the method of Hart, has been copolymerized with vinylacetate vinylpyrrolidone, acrylic acid, and maleic anhydride. From the copolymerization reactivity ratios with vinyl acetate (r1 = 0.33; r2 = 0.33) and with vinylpyrrolidone (r1 = 0.42; r2 = 2) Q and e values were evaluated, in agreement with the Alfrey‐Price equation, to 0.12 and −1.91, respectively. These results are compared to those of other N‐vinyl‐substituted monomers.
Studies in inorganic polyelectrolytes. I. Graham's salt: Dependence of molecular weight on the conditions of formation
Authors: Chatterji A. C. , Bhargava Harihar Nath
Published: April 2003

Nearly 70 samples of Graham's salt were prepared by heating sodium dihydrogen phosphate under varying conditions and then chilling the melt. The molecular weights of the samples, determined according to Strauss by measuring intrinsic viscosity in 0.035 N sodium bromide solution, were found to depend on the conditions of formation, e.g., the nature of the surface of the vessel in which the melt was prepared and the temperature of the melt. Endgroup molecular weights of many samples were also calculated, and an attempt has been made to correlate these calculations with the weight‐average molecular weights. A modification of an empirical formula of Strauss giving molecular weights by a single determination of specific viscosity in water has also been suggested.
A recording sorption kinetics apparatus
Authors: Rosen Bernard
Published: April 2003

Automatic recordings of the rates of sorption and desorption of gases are obtained by measurement of the volume of the ambient gas under conditions of constant pressure and temperature. The apparatus, which approaches microgram sensitivity, is applicable in the field of diffusion of vapors in polymeric solids (and in obtaining the permeability coefficient). It is especially suited for rapid detection of rate changes and provides operational conveniences for extended measurements. Although exhibiting an over‐sensitivity at low pressures, the apparatus does not share the load‐sensitivity limitations of quartz spiral techniques. As a detector of the kinetics of gas evolution or consumption, the apparatus shows promise of application in other fields of research as well.
A convenient laboratory preparation of isotactic polystyrene
Authors: Overberger C. G. , Angj F. , Mark H.
Published: April 2003

Reaction conditions for improving the yield of the crystalline fraction of the product obtained on polymerization of styrene with a heterogeneous catalyst system were determined for the purpose of determining the best conditions for copolymerization studies. The best reaction temperature at atmospheric pressure was found to be about 70°C. The initial ratio of triisobutylaluminum to titanium tetrachloride, if above 3: 1, did not influence the yield of isotactic product appreciably. The addition of lithium aluminum hydride to the catalyst resulted in a slight improvement of vield of isotactic polymer. In the titanium trichloride‐triisobutylaluminum catalyst system, preheating the two catalyst components prior to the addition of solvent and monomer led to improved Activity. Polymerization carried out under conditions of minimum swelling resulted in a lesser amount of amorphous product and improved yield of crystalline fraction. This was accomplished by the use of a nonswelling solvent and the controlled addition of monomer. Maintaining triisobutylaluminum concentration above a given level by stepwise addition during the polymerization greatly increased the activity of the catalyst. In the trichloride system, preheating, together with the use of Nujol as a solvent, controlled monomer addition, and stepwise addition of triisobutylaluminum improved the yield from in average of 0.4 to 6.0 g. of polymer per gram of titanium salt.
Occurrence of globular formations in thermosetting resins
Authors: Erath Edward H. , Spurr Robert A.
Published: April 2003

Electron‐microscopic examination discloses the existence of globular formations, or micelles, in thermosetting resins, varying in apparent diameter from 400–900 A. These micelles are seen in thin sections, in preshadowed carbon replicas, in shadowed plastic strips revealed in profile, and as shadowed individuals. Micelles are abundant in phenolic, diallyl phthalate, and epoxy resins, and comparatively rare in silicones. The existence of micelles is in accordance with the theories of Houwink and Stäger, who consider that polymerization proceeds most rapidly at specific points in the resin; and explains the discrepancies between theoretical and observed tensile strengths. At least in the case of phenolics, micelles appear to arise in filaments formed in the polymerization process. The occurrence of linear arrays is in accordance with this mechanism of micelle formation.
A remark on an equation of state for linear polymers in monolayers
Authors: Kawai Tōtru
Published: April 2003

A few years ago, Singer, following Huggins' method of treatment of high polymer in bulk phase, derived an equation of state for monolayers of large, threadlike molecules. Davies and his co‐worker defined a quantity ω as a measure of flexibility of a polymer chain in the interface, where ω =z– 2 (zis the coordination number of the unit in the postulated two‐dimensional quasi‐lattice in the interface), assuming that each segment in a chain has exactly two positions in which its two neighbors in the chain must fit whenz= 2. Using this definition, they have developed their discussion as to flexibility of polymer chains at the interface. It is one of the purposes of this note to point out that their definition of ω is lacking in its theoretical background. Nevertheless, the values ofzobtained from the observed force‐area relations seem to afford a reasonable order of magnitudes for various types of polymer molecules, in accordance with other data on the flexibility of the polymer chains. Another purpose of this note lies in clarifying the origin of the just‐mentioned contradiction. The reason why the values ofzappear, at first sight, to give a good representation of the degree of flexibility of polymer chains, lies in the remarkable difference in molecular configurations between the “condensed” and “expanded” states at the interface. In conclusion,zor ω resembles the empirical parameter μ often used in the discussion on thermodynamic properties of polymer solutions. Careful analysis of this value is necessary before conclusions can be drawn about the structural characteristics of polymer molecules and the intra‐ and intermolecular cohesions acting on them.
Ultrasonic velocity and adiabatic compressibility in polyelectrolyte solutions
Authors: Sohma Junkichi
Published: April 2003

Ultrasonic velocities in poly(potassium methyl acrylate) solutions were measured at various concentrations. The ultrasonic frequency was (453.8 ± 0.1) kcycles/sec. The ultrasonic interferometer method was used to measure the sound velocity, the relative error of the measurement being kept within 0.1%. Moreover, the temperature variation of the sound velocity in these solutions in the dilute state was measured. While measuring the density, the adiabatic compressibilities at various conditions were estimated. It was found that both the increment of the ultrasonic velocity per unit concentration and the decrement of the adiabatic compressibility per unit concentration showed sharp maxima, at some very dilute concentration, in the case of a pure water solvent, and that these maxima disappeared when the solvent was changed from water to KCI solution. A plot of the ratio of the compressibility for solutions with pure water as solvent, to that for additions with KCI solution as solvent vs. temperature showed an inflection at a given temperature and thereafter leveled off at higher temperatures. The concentration change and temperature variation of the ultrasonic velocity and of the adiabatic conpressibility are qualitatively explained on the basis of Oosawa's theory of polyelectrolyte, solutions.
Influence of the velocity gradient on the viscosity of polystyrene solutions
Authors: Guzmán G. M. , Fatou J. M. G.
Published: April 2003

The purpose of this study has been to study the flow behavior of several polystyrene samples ranging in molecular weight between 1 × 105 and 2 × 101 in several solvents. Intrinsic viscosities corrected for shear effects have been obtained according to several treatments already described in the literature. The results obtained show considerable divergences. The flow behavior of the samples was then studied from a rheological point of view; it is shown that the solutions are more and more Newtonian, the nearer they approach to zero shear stress. Interpretations of the viscosity plots are given. As a consequence, extrapolation of the viscosity curves obtained at very low shear stresses with the use of a special capillary viscometef to zero shear is considered to be the most convenient way of obtaining intrinsic viscosities corrected for shear; such a method is described. The results, in some cases, may be up to 60%, larger than the highest value obtained by the classical methods. The influence of solvent and molecular weight on this shear effect is also considered, and the whole situation is considered, taking into account the possible “structure” of the solutions and the nature of the polymers.
The action of sodium salicylate and related compounds on the proteins of the groundnut (Arachis hypogaea)
Authors: Naismith W. E. F.
Published: April 2003

The 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

A 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

Polymerization 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

Natural 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

Moments 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

Pentachlorophenyl 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

A 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

Analysis 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

Binary 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

Proton 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

Methods 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

Gamma 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

A 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

The 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

The 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

Varoius 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

Sorption 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

The 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

The 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

Gamma‐ 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

In 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.
Light‐scattering measurements on viscose solutions
Authors: Onyon P. F.
Published: April 2003

An exploratory study has been made of the application of light‐scattering measurements to viscose solutions. The effect of aging on molecular weight and second virial coefficient has been investigated for two types of viscose differing only in degree of initial xanthation. By controlled filtration procedures prior to measurement it is possible to obtion information on the upper range of particle size distribution; in this way the presence of a small fraction of material of very high molecular weight has been demonstrated in the viscoses examined. This finding is in accord with results obtained by previous workers using other techniques.
G‐F transformation of actin as a fibrous condensation
Authors: Oosawa Fumio , Asakura Sho , Hotta Ken , Imai Nobuhisa , Ooi Tatsuo
Published: April 2003

The physical feature of the G‐F transformation of action caused by a small amount of magnesium ions was investigated by measuring flow birefringence, light scattering, viscosity, and sedimentation of action solutions at various concentrations of actin and magnesium ions. All experimental results indicate that the G‐F transformation of actin can be regarded as a reversible fibrous condensation. When the concentration of actin is increased at a constant concentration of magnesium ions, fibrous aggregates of actin molecules, F‐actins, can be formed only above a critical actin concentration which is determined by the condition of medium and decreases rapidly with increasing concentration of magnesium ions. Above the critical concentration, all of the excess active actin molecules are transformed into F‐actins. These F‐actins are coexisting with active (G‐)actin molecules, the concentration of which is independent of the concentration of F‐actin and equal to the concentration of active actin at the critical point. The state of apparent units of F‐actins in solution is also determined by the condition of medium and independent of the concentration. With increasing concentration of magnesium ions, the apparent units of F‐actin become longer and longer and their thickness increases. Small globular aggregates are always observed below the critical point of formation of long fibrous aggregates. These experimental results show qualitative agreement with theoretical results obtained by one of the authors on fibrous and globular aggregations of charged macromolecules.
A modified zimm‐myerson‐type osmometer
Authors: Riesel E. , Berger A.
Published: April 2003

A modification of the way of sealing a Zimm‐Myerson osmometer is described. It is shown that the improved instrument gives more accurate and more reproducible results than the one described originally.
A novel catalytic polymerization of olefins. Part II. High polymerization of ethylene by Al‐TiCl4 catalyst
Authors: Fukui Kenichi , Kagiya Tsutomu , Yagi Tetsuya , Shimidzu Takeo , Yuasa Sachio
Published: April 2003

A novel high polymerization of ethylene by Al‐TiCl4 catalyst is studied. The polymer yield increases with higher TiCl4 concentration and with larger amount of Al metal used. With an Al/TiCl4 mole ratio larger than 10, the conversion slightly decreases. The highest conversion is gained at 180°C., and higher reaction temperatures decrease remarkably the yield of solid polymer. The molecular wight of polymers increases with the Al/TiCl4 ratio, but it remains constant at Al/TiCl4 ratios larger than 3. It is highest at 180°C. With respect to the Al/TiCl4 mole ratio, the melting point has a relation similar to that of the molecular weight. It is also maximum at 180°C. The rate equation is determined by some kinetic studies, obtaining the formula ‐dP/dt = 4.37 [TiCl4] exp{‐4800/RT}P for a certain range of reaction conditions. A possible cationic mechanism for this polymerization is suggested.
Colligative properties of polyelectrolyte solutions. V. Activity coefficients of counter‐ and by‐ions
Authors: Nagasawa Mitsuru , Izumi Mikio , Kagawa Ikumi
Published: April 2003

Simultaneous measurements of the activity coefficients of counter‐ and by‐ions in polyelectrolyte solutions were carried out. Sodium polyvinyl alcohol sulfate was used as the sample of polyelectrolyte and sodium chloride as the extraneous salt. The activity coefficient of sodium counter‐ion was determined by using a sodium amalgam electrode and that of chloride ion was determined by a sliver‐silver chloride elctrode. It was found that the activity coefficient of both counter‐ and by‐ions has little relationship with the volume of polymer coil, and that the additivity of counter‐ion activity found for hydrogen ion by Mock and Marshall holds also for sodium ion. It was also found that there is good agreement between the experimental results and the theory of Katchalsky and Lifson if we use their same theory for calculating the volume of polymer coil, although the volume is too large to be considered reasonable.
Gamma irradiation of polymers of arly and alkary methacrylates and acrylates
Authors: Graham Roger K.
Published: April 2003

Poly(benzyl methacrylate) and poly(phenyl methacrylate) appear to degrade exclusively on gamma irradiation; energies for main‐chain, carbon‐carbon bond breaking are 711 and 228 e.v., respectively, which indicates a strong protective effect of the benzene ring. Poly(phenyl acrylate) requires higher doses to cause gelation than do poly(benzyl acrylate) and poly(phenylethyl acrylate), the latter behaving similarly to poly(n‐alkyl acrylates). Absence of hydrogen on the carbon adjacent to the ester link appears to be required to affect the radiation behavior of polyacrylates.
On the coagulation of polymer latices by freezing and thawing
Authors: Barb W. G. , Mikucki W.
Published: April 2003

The particle size characteristics of coagulates obtained by freezing and thawing emulsions of polymers which are hard and glassy at normal temperatures, particularly polystyrene and styrene copolymers, have been studied. It is shown that for a given polymer the particle size distribution is principally determined by the macrostructure of the frozen mass, such as the size of the ice crystals formed and the concentration of polymer in the initial emulsion. The effect of chemical structure of the polymer on the freezethaw coagulation process is discussed and from the results it is suggested that the usual concept of a second‐order (glass) transition is not applicable to very fine latex particles of rigid polymers. This may also explain the formation of continuous films from fine latices at temperatures below the transition temperature of the bulk polymer.
Copolymerization of styrene with vinyl acetate and methyl methacrylate
Authors: Suzuki Momotaro , Miyama Hajime , Fujimoto Shiro
Published: April 2003

By the thermistor method, we measured rates of copolymerization of St(styrene)‐VA(viny1 acetate) and MM(methy1 methacrylate)‐St for various mixing ratios of the two monomers. In the St‐VA system, the large difference between the reactivity ratios of the two monomers causes a large error limit in values of 4, so that we could not find any essential regularities in the variation of 4 with successive mixing ratios. In the MM‐St system, however, where the difference of the two reactivity ratios is not so large, we can determine the values of 4 more precisely and obtain a concrete confirmation of Arlman's theory. As a result, we conclude that, for the MM‐St system (at. 24°C.), the termination constants for mixed radicals are larger than those for homogeneous radicals, and, furthermore, that the rate constant for a normal cross‐termination reaction is about 3 times larger than that of the cross‐termination reaction having a penultimate unit.