bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of urea on the viscosity of deoxyribonucleic acid solutions
Authors: Conway B. E.
Published: April 2003

The effect of urea and sodium chloride on the viscosity of DNA has been examined at very low concentrations and rates of shear in a Couette viscometer. An increase of apparent intrinsic viscosity occurs in urea, but at higher concentrations of the polymer a reduction of viscosity is observed. When treated with urea, the intrinsic viscosity of the nucleic acid becomes lowered by sodium chloride. The results are consistent with a dimeric hydrogen‐bonded structure of the DNA molecule, which undergoes scission in the presence of urea to form more flexible fragments.
Emulsion polymerization of triallyl phosphate with halomethanes
Authors: Frick J. G. , Weaver J. W. , Arceneaux Richard L. , Stansbury Mack F.
Published: April 2003

Trially phosphate has been polymerized in emulsion by itself and with four halogenated methanes: carbon tetrabromide, bromoform, bromotrichloromethane, and carbon tetrachloride. Of the four halomethanes, carbon tetrachloride enters telomer formation only to a slight extent, and bromoform and carbon tetrabromide enter to the greatest extent. In most cases a product consisting of two distinct fractions was formed, a solid‐insoluble polymer, and a liquid‐soluble polymer. The latter is of only a low degree of polymerization, ranging from 1.0 to 2.3 phosphate units. In the course of the reaction, the soluble fraction is formed first and then is partially converted to the insoluble fraction by crosslinking. The polymerization of trially phosphate with bromoform received the most study. In this case the ratio of insoluble to soluble fraction can be changed by varying the amount of initiator and the ratio of bromoform to phosphate. A molar ratio of bromoform to trially phosphate greater than 2.0 yields only monomeric addition products. By the proper choice of conditions a very stable emulsion of a polymer containing phosphorus and bromine can be obtained. This emulsion is suitable for direct application to cotton textiles in order to produce flame‐resistant fabrics.
The scattering of light from thin polymer films. II. Scattering from polyethylene
Authors: Keane John J. , Stein Richard S.
Published: April 2003

Polyethylene may be characterized by use of the light scattering technique applied to the solid polymer. The treatment of Debye and Bueche allows one to assign numerical values to this characterization in the form of two parameters, 〈η2〉, the mean square dielectric constant deviation and a size parameter, α, associated with a spacing within the polyethylene microstructure. This spacing has not as yet been definitely identified with regard to the polyethylene crystallites or spherulites. The numerical values obtained of 2000–3000 A. are too large to be crystal edges and too small to be spherulite radii. The magnitude of the mean square dielectric constant deviation from the average should be associated with the amount of inhomogeneity in the solid, that is, the amount of crystallinity. No direct relation has been found in this work, however, between per cent crystallinity as measured by density and the value of ∠η2〉. The study of 〈η2〉 through a melting and cooling cycle shows a hysteresis effect which is dependent on rate of cooling from the molten state. The effect of heating polyethylene on the value of 〈η2〉 parallels a curve of per cent crystallinity vs. temperature. When the sample is cooled there is a point of maximum scattered intensity and maximum 〈η2〉 at about 106.5°C. Study of the value of α in the melting and cooling process shows it is essentially a constant at all temperatures under equilibrium conditions. If α is studied as a function of time after rapid cooling from the melt to 106.5°C., it is found to maximize after about 20 minutes. This implies that there is a definite spacing between crystalline regions in the spherulite and that, once this spacing is reached, further aggregation can occur only by more crystalline material attaching itself to the periphery of the spherulite with the same spacing or consolidation of existing crystalline regions.
Electrical analogs for viscoelastic systems
Authors: Gross Bernhard
Published: April 2003

With the use of well‐known developments of electric circuit theory it can be shown that a correspondence exists between mechanical relaxation systems and electrical reactance systems. To each line of the mechanical relaxation spectrum corresponds a resonance line, to each line of the retardation spectrum an antiresonance line of the electrical system. Transformation equations between these systems are established. The reactance system can be used as an analog computer. Since resonance and antiresonance frequencies can be determined with conventional a.c. methods, a direct measurement of the spectra becomes possible. Knowledge of the spectra enables one to formulate analytic expressions for viscoelastic functions. The method applies to system with lumped and with continuously distributed parameters, like transmission lines. Dissipation in the circuit elements of the reactance system can be taken into account quantitatively. Other results, which are immediately obtained, are: all viscoelastic systems can be represented by ladder structures. Lines of the retardation spectrum alternate with lines of the relaxation spectrum.
Electron‐exchange polymers. VII. The ion‐exchange and electron‐exchange behavior of hydrophilic hydroquinone copolymers
Authors: Luttinger Lionel , Cassidy Harold G.
Published: April 2003

Countercurrent experiments on two types of sulfonated, water‐swellable, ion‐and electron‐exchange resins were performed. One type contained as commonomers vinyl‐hydroquinone, alpha‐methylstyrene, and divinylbenzene. The other type contained vinylpyridine in addition to the other comonomers. Both types demonstrated rapid, reversible cation exchange with satisfactory capacity, and reversible, slow electron exchange with acid KI and acid Br2. The electron‐exchange capacity was high. The reactions were reversible up to a pH of at least 4.7. At high pH (8.5), slow, irreversible changes occurred. Even at low pH, the resins were gradually broken down by such oxidants as ceric and ferric ions. The cation‐ and electron‐exchange equilibria were shown to be without appreciable effect on one another. Ferricyanide failed to oxidize the reduced form of such resins quantitatively, presumably because of its low potential. Interpretation of the behavior of the resin‐containing vinylpyridine was more difficult, due to the increased complexity, but nevertheless a reasonable amount of base exchange, as well as acid exchange, was demonstrated. Some possible improvements in the stability of these substances at high pH and toward other oxidants, are proposed.
Measurement of viscosity‐average molecular weight of polymer solutions of unknown concentration
Authors: Frisch H. L. , Yeh Si Jung
Published: April 2003

In a number of contexts it is of interest to determine the viscosity‐average molecular weight of a polymer solution whose concentration is not known. Certain ways of ac‐complishing this can be shown to reduce to the comparison of measurements of the specific viscosity of equiconcentrated polymer solutions in two different solvents. The limits of precision of this technique are indicated and checked experimentally on a number of solutions of known composition of mixtures of polystyrene fractions. The agreement between the found viscosity‐average molecular weight and that calculated from the known composition of the polymer fraction mixture is satisfactory.
Effect of field intensity and quantity of electricity upon counterion fixation by polyelectrolytes
Authors: Wall F. T. , Terayama Hiroshi , Techakumpuch Sunt
Published: April 2003

Numerous transference experiments on polyelectrolytes have demonstrated that an appreciable fraction of the counterions move during electrolysis with the polyelectrolyte ion of opposite charge. The present studies were carried out to determine the effect of field intensity and the extent of electrolysis on the apparent degree of counterion fixation. It is found that the degree of ion binding depends upon the applied field and that up to a certain point the association diminishes with increasing field. The results are interpreted to mean that the ions are not all held equally firmly. Some ions are held loosely and move as a kind of atmosphere with the polymer ions only when the applied field is small. Other ions are firmly held and are carried along even in the presence of a strong field which would tend to cause separation of the oppositely charged ions. Using polyacrylic acid partially neutralized with sodium hydroxide, it is observed that from 10 to 20% of the ions that are bound are “loosely” bound and hence not carried along under strong fields. As might be expected, the different degrees of binding are observed to be functions of the degree of neutralization.
The conductivity of a cation‐exchange resin
Authors: Meares P.
Published: April 2003

An equation relating the equivalent conductance of ions in a cation‐exchange resin to their conductance in water and the volume fraction of polymer in the swollen resin has been tested using data for the conductance of potassium ions in crosslinked polymethacrylic acid. The equation is successful for degrees of ionization at which counterion binding is not large and for degrees of swelling sufficiently high for the network to exert no sieve action on the ions. The concentration dependence of conductivity in the resin is determined by a relaxation effect similar to that in free solution and an electrophoretic which has been treated using the Kozeny law for fluid flow in a porous medium. These effects tend to cancel one another so that the concentration dependence is small. When the mean pore diameter of the network approaches the diameter of the counterions the observed conductivity is less than the theoretical value.
An investigation of the dynamic mechanical properties of polymethyl methacrylate
Authors: Maxwell Bryce
Published: April 2003

The dynamic mechanical properties of polymethyl methacrylate have been studied over a frequency range of from 6 × 10−4 to 1.6 × 102 cycles per second and a temperature range of from −20° to +80°C. In order to cover this frequency range with a single piece of apparatus, a modified Kimball‐type testing machine was developed. The testing method is analyzed and the data taken on polymethyl methacrylate and other plastics interpreted in terms of molecular theory. The results on polymethyl methacrylate indicate that three mechanisms of relaxation are involved in the response of the material in this frequency and temperature range. The importance of dynamic mechanical properties to the practical engineering design of plastics components is discussed. It is suggested that three‐dimensional plots of modulus or loss factor vs. frequency and temperature is the best method of describing the mechanical behavior of plastics at their use conditions.
Studies on cation exchangers. I. Infrared spectrophotometric determination of ion exchange equilibrium constants and activity coefficients in resin phase
Authors: Sobue Hiroshi , Tabata Yoneho
Published: April 2003

The ion exchange equilibrium constants were obtained by measurements of infrared spectra of the ion exchange resin phase, using carboxymethylcellulose film (degree of etherification 0.66) as ion exchanger. The apparent constants are calculated by the following equation:

where A and B are the concentrations of the two exchangeable cations, respectively, rA is the valence of the A ion, γA is the activity coefficient of the A ion in the electrolyte solution, ϵA is absorption intensity of carbonyl band of the carboxy radical having the A ion in an exchanger, and k is a constant. The dependence of the apparent equilibrium constants on pH and the ionic concentration in the electrolyte was investigated in the Na‐H, K‐H, NH4‐H, Ca‐H, and Sr‐H exchange systems. Further, the activity coefficients of the exchangeable ions in the resin phase were evaluated in both the uniunivalent and unidivalent exchange systems. It is concluded that the abnormal behavior of the coefficients in the resin phase would be explained by the interaction energy between the ion pairs in the resin phase, independent of the concentration of the electrolyte solutions, in the range of comparatively dilute electrolyte solutions.
Molecular weight distribution of thermally polymerized triglyceride oils. I. Application of flory's polycondensation theory
Authors: Hoeve C. A. J.
Published: April 2003

It is shown that Flory's polycondensation theory can be applied to polymerized oils if in the original oils the different acids are esterified at random with the alcohol groups of glycerol. This is approximately the case. Departures from this random state are smoothed out by ester interchange when the oil is heated at 300°C. for long periods, as is the case in polymerized oils manufacture. The amount of monomeric triglycerides in polymerized oils is calculated and compared with the experimental result. The amounts of some other species are also calculated.
Molecular weight distribution of thermally polymerized triglyceride oils. II. Effect of intramolecular reaction
Authors: Hoeve C. A. J.
Published: April 2003

In Flory's theory it is assumed that no ring formation occurs. This theory can in simple cases be extended to include this effect. Theoretical amounts of ring formation in the case of polymerized oils are compared with experimental results.
Component effects in phase separation of polymer‐polymer‐solvent systems
Authors: Kern R. J.
Published: April 2003

The nature of phase separation in polymer‐polymer‐solvent systems was investigated. Threshold concentrations necessary for the separation of polystyrene and poly(methyl methacrylate) in a variety of solvents were determined. Only a rough correlation between cohesive energy densities and solvent compatibilizing powers was found. Separation data for combinations of a number of substituted polystyrenes were determined in reference solvents. The general occurrence of phase separation in these systems is thought to stem from the unique array of functional groups presented by a polymer molecule to its environment. Phase separation in conjunction with available heats of mixing indicate the exothermic heat of mixing chlorobenzene and toluene is due to interaction of the chloro group with an aromatic ring. Changes in chain extension and solvation as a function of temperature were detected by means of phase separation.
Diffusion and gelation in polyadditions. I. Vindication of the classical network theory of gelation
Authors: Gordon Manfred , Roe Ryong‐Joon
Published: April 2003

In this, the first of a series of four papers, the theory of diffusion control of the gelation in polyfunctional polyadditions is rejected. It is shown experimentally, that the termination step in a model system is unaffected by diffusion control until after gelation. It is shown theoretically that diffusion control of the crosslinking step sets in even later. Investigations by Grün, and by Vaughan, are relevant to this demonstration. Quantitative application of the Stokes‐Einstein theory of diffusion confirms the conclusions reached. In the absence of diffusion‐controlled crosslinking, alternative causes are examined for observed delays in gelation. These causes are intramolecular cyclization and chain transfer effects. There are well‐known mass law effects of dilution in polyfunctional systems. However, progressive dilution with monovinyl monomer in polyaddition does not—in contrast to the effects of inert diluent in polycondensation—favor internal cyclization. The true mass law effects of such dilution can readily be allowed for.
Preparation and properties of fibers containing mixed polymers. III. Polyacrylonitrile‐silk fibers
Authors: Cates David M. , White Howard J.
Published: April 2003

Fibers containing both polyacrylonitrile and silk have been spun using an aqueous solution of ZnCl2(56% ZnCl2by weight) as solvent. The relative polymer proportions ranged from 100% polyacrylonitrile to 20% polyacrylonitrile. The conditions under which the fibers were spun are discussed, as are the results of various measurements on the fibers. The x‐ray diffraction patterns, optical appearance, absorptive capacity for water and an acid dye, electrical resistivity, and mechanical properties of the fibers were studied. A few measurements on the compatibility of the polymers in solution are also reported. The results suggest that the fibers contain small, discrete regions of each polymer which are neither highly crystalline nor strongly oriented.
Some isomorphous copolyamides
Authors: Cramer Francis B. , Beaman Ralph G.
Published: April 2003

Various copolyamides obtainable from heptamethylenediamine (7) and bis(3‐aminopropyl) ether (303) combined with adipic acid (6) and terephthalic acid (T) were prepared. They were characterized thoroughly as bulk polymer (visual appearance, viscosity number, polymer melt temperature, solubility), as melt‐pressed films (water absorption, glass transition temperature, crystallinity) and as melt‐spun, drawn monofils (tenacity, elongation, initial modulus, compliance ratio, tensile recovery, work recovery, orientation, crystallinity, fiber stick temperature, zero strength temperature, and crystalline melting point). The reality of isomorphism in polyamides was definitely established by the linear dependence on composition of all physical properties measured for the copolymer system 303‐6/7‐6. The copolymer systems 303‐T/7‐T, 303‐6/7‐T, and 7‐6/303‐T showed decreasing tendency toward ideal isomorphism, and the system 303‐6/303‐T showed deviation from perfect isomorphous behavior in all properties. It is concluded that in the aliphatic diamines used, and ether oxygen fits well as a substitute for a methylene group, but the benzene ring fits poorly as a substitute for the four‐carbon aliphatic chain of adipic acid.
Effect of some organic acids on the diffusion of orange II in nylon 66
Authors: Browne Colin L. , Steele Richard
Published: April 2003

The sorption of sixteen organic acids by nylon yarn has been studied at 30°C. and the isotherms were found to fit the empirical Freundlich equation. Heats of sorption indicated that the acids are probably sorbed by physical solution in the amorphous regions of the polymer. The effects of some of these acids on the diffusion coefficient, equilibrium sorption and activation energy of diffusion of orange II in nylon film have been determined. Benzoic acid and salicylic acid were found to act as “swelling agents” and increase the diffusion coefficient of the dye, while β‐naphthalenesulfonic acid and p‐toluenesulfonic acid had no marked effect on the diffusion constant. The effects of the acids in reducing requilibrium dye sorption were found to be dependent on the dye‐like character of the acid concerned. All of the acids increased the activation energy of diffusion for the dye, so that the increases in diffusion coefficient were attributed to increase in entropy of activation.
The x‐ray diffraction, birefringence, and infrared dichroism of stretched polyethylene
Authors: Stein Richard S. , Norris Forrest H.
Published: April 2003

The results of a study of x‐ray diffraction, birefringence, and infrared dichroism on a series of polyethylene samples elongated between 0 and 400% are presented. It is shown that, by using any two of the three methods together, one may determine individually the orientation of the amorphous and crystalline portions of the polymer. The results of the third method may then be predicted. Both amorphous and crystalline regions orient appreciably upon stretching. The amorphous orientation is somewhat lower than that of the crystallites. Many of the amorphous chains appear to become completely stretched out. The results indicate that the degree of crystallinity remains constant during stretching and that the oscillator strength of the CH2 rocking vibration is also constant.
The rotation of polar groups in high polymers
Authors: Lewis Charles W. , Hogle Donald H.
Published: April 2003

The dielectric constant and loss factor of cyanoethylcellulose have been studied as functions of frequency at four temperatures. The unusually high value of the dielectric constant (13.3 at 60 cycles and 25°C.) is attributed to rotation of the CH2CN group. Anomalous dispersion in the megacycle region also supports this interpretation. Similar properties are displayed by polyvinyl‐β‐cyanoethyl ether, but allyl cyanide polysulfone gives evidence of steric hindrance.
Poly‐n‐butyl methacrylate. III. Dilute solution properties by viscosity and light scattering
Authors: Chinai Suresh N. , Guzzi Rudolph A.
Published: April 2003

Poly‐n‐butyl methacrylate prepared by the emulsion technique was fractionated three times by the fractional precipitation procedure to obtain eight fractions. Relationships between viscosity and weight‐average molecular weight were obtained in both an ideal solvent, isopropanol, and a nonideal solvent, methyl ethyl ketone. These relationships are represented by equations:

The effect of the size of the pendant groups (‐methyl, ‐ethyl, and n‐butyl ester) on the degree of extension of macromolecules in ideal solvents is discussed. It was found that the degree of flexibility of the macromolecule increases as the size of the pendant group increases. These results are believed to be due to the short‐range interference effect of the solvent molecule on the degree of free rotation of the macromolecule.
A comparison of the dielectric dispersion behavior of corn amylose and amylopectin acetates
Authors: Ferraro Charles F. , Maurer John J. , Zagar Walter T.
Published: April 2003

The dielectric constants and loss factors of disks of corn amylose and amylopectin triacetates, unplasticized and plasticized with 15% by weight of dioctyl phthalate, dimethyl phthalate, and diphenyl were measured at ten frequencies throughout the range 102 to 105 c.p.s. over the temperature interval of −78 to 80°C. A two‐terminal dielectric cell constructed from stainless steel and Teflon is described which may be thermostated by direct immersion into liquid baths. The values of ΔE*, ΔS*, and ΔF* for the dielectric relaxation processes occurring in each of the eight systems were calculated from the variation with frequency of the temperature at which the maximum values of the loss factors are found. The similarities and differences which are present in the dielectric dispersion data are discussed in terms of the molecular structures of amylose and amylopectin acetates, and possible mechanisms are suggested to explain the observed behavior.
Dielectric dispersion in solutions of copper‐cellulose nitrate complex
Authors: Pauley J. L. , Testerman M. K.
Published: April 2003

The dielectric dispersion of solutions of cellulose nitrate has been reaffirmed; however, the dispersion has been attributed to the formation of a copper‐cellulose nitrate complex. The phenomena can be explained in the light of present theories as a resonance phenomena and occurs in the unusual frequency region of 100 to 500 kc. The variation in the dispersion frequency can be explained in terms of a “lumped constant”, oscillating, polymer aggregate. The general properties of a stiffened random coil are experimentally confirmed.
Hydrodynamic properties of polyelectrolytes. Part IV. Viscosity of polyelectrolytes
Authors: Mathieson A. R. , Porter M. R.
Published: April 2003

The different types of viscosity behavior which have been observed for polyelectrolytes are discussed and classified. Data are presented for sodium deoxyribonucleate and for sodium polyacrylate of different molecular sizes, and give information on the influence on the viscosity of the degree of polymerization and the flexibility of the molecule. The influence of the shear gradient is also considered. A qualitative interpretation is given based on the size of the polyions and their mutual interactions.
A redox system utilizing N‐nitrosoacetanilide for the emulsion polymerization of styrene and of butadiene‐styrene
Authors: Kolthoff I. M. , Brackman D. S. , Meehan E. J.
Published: April 2003

The rate of reaction of N‐nitrosoacetanilide with ferrous versenate in slightly acid solution has been shown to be equal to its rate of rearrangement. One mole of ferrous versenate is oxidized per mole of benzenediazonium chloride at pH 5.0. In the two‐phase benzene‐water system 1.6 ± 0.1 mole of ferrous versenate are oxidized per mole of N‐nitrosoacetanilide, which ratio decreases to 1.1 ± 0.1 when ethanol is added to the system. N‐Nitrosoacetanilide in combination with ferrous versenate or citrate in slightly acid medium is a redox system for the initiation of the emulsion polymerization of styrene and butadiene‐styrene. The initiating efficiency of this combination for styrene emulsion polymerization decreases continuously up to about 20% conversion when a constant value of approximately 0.2 is found.
Light scattering properties of an isotactic polymer solution
Authors: Peaker F. W.
Published: April 2003

A polystyrene of isotactic character having a melting point (221°C.) and a degree of crystallinity in the solid state of 40%, was found to be partially soluble in toluene at 100°C. Light scattering measurements on the soluble portion indicate that the material has the high weight‐average molecular weight of 8.93 × 106. The dimensions of the molecules in solution agree with those deduced from the theoretical treatment of the polydispersed random coil, and the second virial coefficient is of the expected order.
The structure of polysiloxanes: Molecular size and shape of highly crosslinked polymethylsiloxanes in solution
Authors: Price Fraser P. , Martin Sylvia G. , Bianchi Joseph P.
Published: April 2003

Measurements of solution light scattering and solution viscosity have been made in ideal solvents on polymethylsiloxanes containing large percentages of crosslinking units. For the 1.5 Me/Si and 1.8 Me/Si polymers [η] = 0.326 M0.21 and [η] = 0.240 M0.28, respectively. Densities of the polymer molecules within their spheres of action have been calculated from the viscosity relationship of Flory. They are 0.10 and 0.05 g./cc. for the 1.5 and 1.8 Me/Si resins, respectively. These are to be compared with 0.007 g./cc. for a linear polydimethylsiloxane (Me/Si = 2.0). The high densities, the low viscosities, and the low viscosity exponents lead to the conclusion that these molecules are, to good approximation, spheres of constant density, a sort of micromicrogel.
Copolymerization of vinyl siloxanes with organic vinyl monomers
Authors: Pike Ronald M. , Bailey Donald L.
Published: April 2003

A series of simple vinyl siloxanes containing monofunctional, difunctional, and trifunctional silicon atoms has been copolymerized with various organic vinyl monomers. It is now possible to predict the behavior of vinyl siloxanes of complex structure in copolymerization reactions with these vinyl monomers. The structure of the vinyl siloxane does not appreciably affect the total rate of copolymerization or its reactivity toward a given organic vinyl monomer. Vinyl siloxane monomers have comparable reactivities to monomers such as vinyl acetate, vinyl chloride, and perfluorovinyl chloride but are less reactive than acrylonitrile, styrene, and N‐vinylpyrrolidone. In copolymerization reactions involving vinyl siloxanes the total polymerization rate and the molecular weight of the copolymers are markedly affected by the amount of vinyl siloxanes in the monomer mixture. An increase in the percentage of vinyl siloxane in the monomer mixture results in a decreased polymerization rate and copolymers having lower molecular weights.
Polymerization of methyl methacrylate in polyisoprene solutions
Authors: Allen P. W. , Merrett F. M.
Published: April 2003

The polymerization of methyl methacrylate in solutions of three polyisoprenes (rubber, gutta‐percha, and chicle gutta) results in a product which can be separated by fractional extraction and precipitation into free polyisoprene, free polymethyl methacrylate, and a compound of the two polymers. The molecular weight of the polymethyl methacrylate component in this compound is about the same as that of the free polymer. In solution this compound hinders the precipitation of polyisoprenes and this phenomenon is responsible for previous failures to separate free polyisoprene from reaction products by fractional precipitation. Polyisoprenes retard the polymerization, the effect increasing from chicle gutta (Mn ∼ 15,000) to rubber (Mn ∼ 500,000).
The oxidation of polybutadiene. II. Property changes during oxidation
Authors: Bauman Richard G. , Maron Samuel H.
Published: April 2003

The oxidation of emulsion polybutadiene has been followed by observation of changes in gel content, swelling index, intrinsic viscosity, and infrared spectra. The results show that, whereas simple heating of the polymer leads primarily to crosslinking, the presence of oxygen causes both scission and crosslinking, with the predominance of either of these processes being dependent on the amount of oxygen absorbed. Increase of temperature or degree of oxidation favors crosslinking. During oxidation acid, ester, aldehyde, ketone, ether, and alcohol groups appear, but their relative proportions remain essentially constant. Also, a large extent of the oxidation occurs without resultant decrease in unsaturation, indicating, in all probability, that the double bond is not the direct point of oxygen attack.
Nature of the end groups in polystyrene prepared using benzoyl peroxide as sensitizer
Authors: Bevington J. C. , Brooks C. S.
Published: April 2003

Samples of polystyrene prepared using benzoyl peroxide labeled with carbon‐14 in the carboxyl group only have been used to establish the conditions necessary for complete hydrolysis of the ester end groups in the polymers. Polymers prepared using 14C‐benzoyl peroxide either uniformly labeled or labeled in the benzene rings only, contain both labeled benzoyloxy and labeled phenyl end groups. From the behavior of these polymers on hydrolysis, the proportions of the two types of end groups can be determined accurately; these proportions depend upon the conditions under which the polymers are prepared.
Equilibria between polycapramide and water. I
Authors: Fukumoto Osamu
Published: April 2003

To increase the degree of polymerization of polycapramide, there are two processes: addition of cyclic lactam to linear polymer, and condensation between linear polymers with each other. But after the equilibrium between linear polymer and cyclic lactam is attained, the degree of polymerization is determined only by the condensation. Since the solubility of water in molten polycapramide is less than 0.5%, Henry's law holds well. The equilibrium constant of the condensation is expressed by logK= −0.30 + 1495(1/T). Under any constant vapor pressure of water, the degree of polymerization is increased as the temperature rises. When no stabilizer other than water is used, the number‐average degree of polymerization is determined by logP̄n= 5.97 − 1253(1/T) − ½ logp.
Association and entanglement in high polymers. I. Effect on viscometric properties of dimethylpolysiloxanes
Authors: Merker R. L.
Published: April 2003

A theory of association and entanglement explaining many of the anomalous physical properties of linear high polymers has been evolved. The theory was developed from a Carothers type of relationship in which the apparent molecular weight resulting from entanglement and/or association of long polymer chains was related to the true molecular weight of the free molecules. The effects of molecular weight and association or entanglement have been related to the viscometric behavior of linear polymers. Good agreement between theory and experiment was obtained by introducing experimentally determined constants into the theoretical expression relating molecular weight and zero shear bulk viscosity for dimethylpolysiloxanes and polyisobutylenes. Theory predicts the observed increase in energy of activation for viscous flow and increase in non‐Newtonian behavior with increasing molecular weight.
Density, infrared absorption, and crystallinity in 66 and 610 nylons
Authors: Starkweather Howard W. , Moynihan Robert E.
Published: April 2003

The intensities of crystalline and amorphous infrared bands of 66 and 610 nylon films were plotted against density. The curves were extrapolated to zero intensity to give revised values for the amorphous and crystalline densities which are probably more accurate than those previously used. The amorphous density of 610 nylon was in agreement with the value previously measured on quenched films, but the amorphous density of 66 nylon was about 2% lower. The new values for the crystalline densities are somewhat lower than those calculated from x‐ray diffraction data.
Degradation of addition polymers by ultrasonic waves
Authors: Mostafa M. A. K.
Published: April 2003

A general solution, using matrix algebra, of the rate equations representing the degradation of long‐chain molecules is given. The solution can be applied to any similar set of equations under varied conditions. Degradation of homogeneous samples is considered and the results obtained are in agreement with previous works. Degradation of addition polymers of known initial size distribution is considered. The result obtained shows, contrary to the findings of Jellinek and White, that (1) the weight‐average chain length at the end of degradation is dependent on the initial average chain length; and (2) the number of molecules at the end of degradation decreases slightly as the chain length increases from monomer to the intermediate chain length y.
Departures from random mixing in polymer‐liquid systems
Authors: Booth C. , Gee G. , Williamson G. R.
Published: April 2003

The vaper pressure of ethyl acetate‐natural rubber mixtures has been studied at 25 and 50°C. over the whole range of miscibility. Current statistical theories of polymer solutions fail to account quantitatively for the observed entropy of mixing; the discrepancy is attributed to the occurrence in this system of non‐random mixing.
De l'influence d'une petite modification structurale apportée à une semimacromolécule sur les propriétés thermodynamiques de ses solutions
Authors: Lienhart A. , Widemann M. , Banderet A.
Published: April 2003

On a préparé une série de dérivés du n pentatriacontane, considérés comme substances modèles de macromolécules. Leurs solutions benzèniques diluées, ont permis d'étudier l'influence du substituant sur l'énergie libre molaire partielle \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\Delta F_0 } $\end{document} du solvant, en particulier sur le deuxième coefficient A2 du développement de \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\Delta F_0 } $\end{document} en série de puissances de γ, la concentration molaire du soluté. Les coefficients ont été comparés directement à celui de la substance mère par la méthode de la distillation isotherme. II apparait que le branchement augmente A2, alors que l'ablation d'un CH2 de la chaǐne ou un substituant phényl n'ont que peu d'influence. Le substituant Cl, et plus encore I'introduction d'une double liaison font au contraire décroǐtre A2. Dans ce dernier cas, on a pu constater que l'effet est additif (si les deux doubles liaisons sont assez éloignées) et indépendant de la position de la double liaison dans la chaǐne. La mesure directe de la chaleur de dilution semble donner la somme de la vraie chaleur de dilution, plus une chaleur de désorbtion. Ces chaleurs mesurées sont relativement peu différentes d'un produit à l'autre. Leurs différences permettent d'estimer l'influence de ces substituants sur l'entropie molaire partielle du solvant \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\Delta S_0 } $\end{document} en particulier sur le deuxième coefficient b de son développement en série de γ. On retrouve sensiblement les influences signalées sur A2.
Sorptive properties of glasslike polymers
Authors: Kargin V. A.
Published: April 2003

The swelling and solution of elastic polymers, like the mixing of liquids, results in the formation of equilibrium systems. In the interaction of conventional glasses and liquids, however, quite different phenomena appear and cause nonequilibrium systems to form. The density of molecules in conventional glasses is similar t o that of tightly packed liquids, but the diffusion rates are very low. Such glasses sorb practically nothing at low vapor pressures. Sorption begins only when the vapor pressure and the concentration of sorbed liquid in the surface layer are sufficient to cause the glass to melt. It should be noted that in this case sorption shows a sharp rise and an equilibrium solution forms. The degree of tight packing of polymeric glasses varies considerably, decreasing with increasing molecular weight and rigidity of the chain molecules. This packing can be estimated by comparing the densities of the polymers with the volume of the molecular groups of which these polymers consist, the latter being obtained from x‐ray data, or by comparing the density of the monomer with that of the polymer. Cellulose, which unlike tightly packed glucose sorbs water over the whole range of vapor pressures, is a typical example of a loosely packed polymer. The effect of the density of packing on the sorbing properties of glasses can be more clearly demonstrated by the sorption of ethylbenzene by polystyrenes of different molecular weights. Low molecular weight polystyrenes dissolve in ethylbenzene without any heat production and sorb ethylbenzene from the vapor at high pressures only. This process results in the formation of a solution. High molecular weight polystyrenes, however, dissolve in ethylbenzene, producing heat, and sorb ethylbenzene a t all vapor pressures. The loose packing of polymers is the result of the long relaxation times existent in glasses. When the deformation time of the polymer is less than the volume relaxation time, the polymer becomes porous. Thus both the sorbing properties and the heats of solution of polystyrene become more pronounced during orientation. The degree of tight packing again increases at heats close to the glass point. Thus polymeric glasses hold an intermediate position between liquids and hard porous sorbents, such as silica gel, in regard to their sorbing properties. Unlike hard sorbents, however, they are apt to change their structure not only under external influence but also in the process of sorption.
A case of antithixotropy
Authors: Crane J. , Schiffer D.
Published: April 2003

Solutions of polyisobutylene in tetralin were observed to show antithixotropy. Quantitative results are given, and comparison is made with a non‐Newtonian liquid of constant viscosity and with one which shows (positive) thixotropy.
On the technique of measuring flow birefringence
Authors: Janeschitz‐Kriegl H.
Published: April 2003

A discussion is given of a number of problems concerning the measurements of flow birefringence and an apparatus is described in which the uncertainties arising from these problems are reduced as much as possible. The problems discussed are: diffraction of light in the narrow gap formed by the cylinders; influence of the optical properties of the material of the cylinders; building up of pressure differences in an apparatus with variable width of slit (Kuhn et al.); appearance of a temperature gradient in the rotating apparatus, disturbing the optics of the system. The apparatus built consists of a stationary outer cylinder and a rotating inner cylinder with a narrow gap in between. A narrow pencil of light runs through the gap and parallel to the cylinder axis. The light, which deviates from the pencil due to diffraction followed by reflection at the cylinder walls, is intercepted by an extra slit behind the apparatus. The cylinders are made of dark glass because of its optical properties. The heat generated in the gap due to the gradient of flow is removed by an extra convection current parallel to the axis of the apparatus and therefore perpendicular to the main flow. In this way it is possible to keep the temperature nearly uniform in the gap.
Dielectric relaxation in dilute solutions of polar chain molecules
Authors: Van Beek L. K. H. , Hermans J. J.
Published: April 2003

The dielectric properties of polymer solutions are calculated on the assumption that each polymer molecule may be divided inNsubmolecules whose end‐to‐end distance shows Gaussian distribution. Electrical charges of alternating sign are attributed to the ends of these submolecules. The equations of motion are given for free‐drained structures. From these equations of motion the diffusion equation in configuration space is constructed. The average dipole moment can be calculated by a simple integration procedure. It is found that there should be two dispersion regions, one at low frequencies proportional to 1/N2and one at high frequencies independent ofN. The high frequency maximum in the loss curve has a shape which is very nearly that for a process with a single relaxation time.
Sur la coacervation des polyamides
Authors: Turska Eligia , Łczkowski Marceli
Published: April 2003

On a étudié le système: polyamide‐phénol‐glycol‐ethylenique‐equ, qui permet d'‐obtenir le coacervat des polyamides de l'ε‐caprolactame. On a caractérisé l'influence de l'addition des différants nonsolvants sur les variations de la viscosité intrinsèque des solutions des polyamides. On a constaté une influence caracteristique de l'eau, qui est dailleurs un composant indispensable pour la formation du coacervat dans le système étudié. On a determiné la correlation entre le poids moléculaire du polymère et la concentration des composants d'un cǒté et la zone de la coacervation et la composition des phases de l'autre. On a essayé de donner une interprétation du phénoměne considerant le rǒle decisif de l'eau. L'eau agit comme facteur qui provoque un fort pelotonnage des macromolécules et en měme temps les empeche de s'unir par des liaisons hydrogène intermoleculaire en bloquant les groupes NH.
Interaction of polyamides with solvents. I. A preliminary survey of the swelling of crosslinked nylon 66 in various types of solvents
Authors: Valentine L.
Published: April 2003

The swelling in various liquids of discs of nylon 66, crosslinked by the radiation from an atomic pile, has been interpreted using the Flory‐Rehner treatment of the swelling of cross‐linked networks. Values of χ1, the polymer‐solvent interaction parameter, found in this way have been discussed in terms of the physical properties of the liquids. The solvent power of about twenty phenols can be correlated with their known ability to form hydrogen bonds. Intramolecular bonding, as in guaiacol or o‐chlorophenol, reduces the solvent power. Partially hindered phenols, i.e., those with one bulky hydrocarbon group ortho to the hydroxyl, show high solvent power, probably because polymer‐solvent interaction is not hindered sterically as much as solvent‐solvent interaction. Other classes of solvents, e.g., inorganic and organic acids, inorganic salts in hydroxylic solvents, are also discussed briefly. Some implications of these results in such technological fields as plasticizers and dyeing assistants are suggested.
Sorption and diffusion in ethyl cellulose. Part II. Quantitative examination of settled isotherms and permeation rates
Authors: Barrer R. M. , Barrie J. A.
Published: April 2003

A quantitative analysis has been made of sorption isotherms and of diffusion data obtained with benzene, acetone, and methanol in ethyl cellulose. The concentration range covered was for volume fractions of penetrant not above 0.1. In this range reproducible measurements were possible. The sorption data show significant departures from the lattice theory of solution. In particular, isotherms tend to curve in the same sense as the Langmuir isotherm; heats of dilution are exothermal; and entropies of dilution are negative. The sign of heats of dilution and the isotherm shapes can be explained if gaps in the polymer provide sorption sites, but the entropy values cannot. An additional ordering or immobilization of the structure around the site, or of penetrant molecules on it, is required. In all these effects it is the nonpolar molecule benzene which shows them most clearly. Diffusion coefficients, D, Arrhenius energies of activation, Ea, and the coefficients D0 in the equation D = D0 exp { −Ea/RT} all depend upon the molecular dimensions of the penetrant. The permeability and D change as the concentration of penetrant increases, except for methanol. These and other aspects of diffusion have been discussed, and compared with results obtained in other polymers.
Gonflement des copolymères greffés d'acrylonitrile sur le polyéthylène dans le dimethylformamide
Authors: Chapiro Adolphe
Published: April 2003

On a étudié le gonflement dans le dimethylformamide des copolymères greffés d'acrylonitrile sur le polyéthylène préparés par deux méthodes radiochimiques. Les échantillons utilisés étaient des films qui avaient conservé la forme du film de polyéthylène de départ malgré des expansions parfois considérables. Le gonflement de ces copolymères était nul à la température ordinaire mais il était très important à 110°. L'étude de la cinétique du gonflement a montré que la gonflement se faisait en deux étapes: un “gonflement initial” très rapide (10 min. à une heure) suivi d'un gonflement plus lent qui atteignait généralement une valeur limite; toutefois certains copolymères obtenus dans des conditions bien déterminée tendaient à se dissoudre complétement. Les valeurs du taux de gonflement initial et du taux de gonflement limite sont fonction à la fois de la composition des copolymères et de la température à laquelle ils ont été préparés. Les courbes du taux de gonflement en fonction du taux de greffage présentent toutes un maximum correspondant à une composition de 87,5% en polyacrylonitrile. La relation entre le taux de gonflement et la température de préparation des copolymères est assez complexe. Le gonflement est maximum pour des copolymères préparés entre 95 et 135°. Ces différents résultats sont interprétés en tenant compte des conditions particulières dans lesquelles les copolymères ont été préparés. On en déduit en particulier que la structure des copolymères greffés est fonction de la température de greffage. Dans les copolymères préparés en dessous de 95°, les zones cristallines du polyethylène empěchent la pénétration de l'acrylonitrile et le greffage est hétérogène à l'échelle microscopique, aussi le gonflement dans le diméthylformamide est‐il gěné par l'existence de domaines faiblement greffés. Au dessus de 135° les branches croissantes de polyacrylonitrile ont tendance à se recombiner entre elles et on aboutit à des copolymères réticulés.