bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies in chain transfer. III. Determination of chain transfer coefficients from catalyzed polymerization data
Authors: Palit Santi R. , Nandi U. S. , Saha N. G. 
Published: April 2003

AbstractBased on a general equation correlating DP and rate for catalyzed polymerization in the presence of solvents, an experimental method has been devised for determining all three transfer coefficients, viz. monomer transfer (CM), solvent transfer (CS), and catalyst transfer (CI), in a simple and straightforward way. Three types of methods are possible for solvent transfer determination: (1) by determining the slope of

at constant 1 (catalyst): M (monomer) ratio; (2) by determining the intercept of

at constant S/M; and (3) by direct use of the general equation, especially using a catalyst whose CI is known to be zero. It has been further shown that the existing method (slope of 1/P versus S/M) in uncatalyzed polymerization would give correct results for all solvents only over the range in which the rate of uncatalyzed polymerization is proportional to the square of monomer concentration. It has also been pointed out that, in systems in which the more usual rate equation, RP = KP (ki/kt)1/2I1/2M3/2 is valid, the slope of 1/P versus S/M (at constant I/M) would give correct CS values for catalyzed polymerization also.
Polarity in copolymerization
Authors: Ham G. E. 
Published: April 2003

AbstractIndependent means of assaying free radical copolymerization polarity (e) values from ionic copolymerization data are outlined. Interpretation of ionic (carbanionic and carbonium) copolymerization data in general in the light of these same e values is discussed. An extension of Wall's equation:

to allow prediction of ionic copolymerization reactivity of untested combinations is offered. For carbanionic systems:

where P1 and P2 are empirical functions of the polarity e of Alfrey and Price. For carbonium systems:

where N1 and N2 are different empirical functions of the polarity e. Advantages and limitations of the technique are discussed.
Polymers and group interactions. I. Synthesis of polyampholytes
Authors: Vrancken M. , Smets G. 
Published: April 2003

AbstractIt is possible to obtain a polyampholyte characterized by the presence of primary amine and carboxylic functions by a method based on the mutual reaction of functional groups along the polymeric chain. The great advantage of this method is the production of copolymers of a new type, from which the internal structure is well defined. In the present case the method is based upon interaction of an acyl chloride unit with a neighboring isocyanate function; these isocyanate functions have been introduced into the chains by two different methods, the Curtius reaction (sodium azide on polyacroyl chloride) and the Lossen reaction (hydroxylamine base on polyacroyl chloride). The solvents used were dioxane and dimethylformamide; the reactions were performed at ebullition. Higher boiling solvents yield an increasing amount of insoluble material. Both syntheses give end‐products with the same properties. The structure of the polymers has been established from conductometric and potentiometric titration curves and also from nitrogen analysis. It was found that the interactions produce the formation of rings along the chain, and that these interactions are limited, as can be foreseen from statistical reasons; the residual groups remain free and become carboxylic functions after hydrolysis, or they react further and are transformed into amino functions. The final products are to be considered as copolymers of vinylamine and acrylic acid with a predominant alternate structure, and in which a given amount of amino groups have reacted with a neighboring acid function yielding lactam rings. However, these pyrrolidone units may be easily opened by alkaline hydrolysis, yielding thereby a polymeric chain with free amino and carboxylic functions, from which the proportions are approximately equivalent at high nitrogen content (12.5–13% N2). At lower nitrogen content the proportion of free carboxylic functions predominates; e.g., at 9.8% N2 there is an excess of 24% acidic functions. Determinations before and after hydrolysis allow the establishment of the internal structure of the copolymers; the proposed structure has been confirmed by benzoylation and deamination reaction and analysis of the benzoylated and deaminated copolymers.
Polymerization of diallyl phthalate
Authors: Haward R. N. 
Published: April 2003

AbstractUsing a simple statistical model, the probability of intramolecular reaction is calculated for the polymerizing diallyl phthalate molecule. The calculation is based on the assumption of the free rotation of bonds and a restriction of the chains considered to 9 and 11 links. Allowance is made for the different types of terminal structure produced during the reaction. The result agrees with the experimental work of Simpson in that an appreciable probability is found. (Theoretical 31%, experimental 41%, saturated groups). It is probable that the accuracy of the results obtained has been increased by reason of the fact that different imperfections in the model affect the result in opposite senses.
Adsorption of high polymers from solution on to solids. II. Adsorption of polystyrene on charcoal
Authors: Jellinek H. H. G. , Northey Helen L. 
Published: April 2003

AbstractRates of adsorption of polystyrene on to charcoal from methyl ethyl ketone solutions are influenced by water present in the solvent causing resting periods. These resting periods disappear when water‐free solvent is used. The type of adsorption isotherm and molecular weight relationship are not influenced by the presence of water. The temperature coefficient for rate of adsorption is small.
The curing of silicone rubber with benzoyl peroxide
Authors: Bueche A. M. 
Published: April 2003

AbstractThe formation of crosslinks in silicone rubber by benzoyl peroxide was studied by tension and swelling techniques as a function of curing conditions and filler content. The ability of benzoyl peroxide to form crosslinks was found to decrease markedly as the peroxide concentration was increased. The peroxide seems to form crosslinks in an amount independent of the concentration of the silica filler. High crosslink concentrations were found to be necessary to fully utilize the polymer‐filler attachments. Values for the bulk and solution densities of silicone gum and the specific volume of the filler in silicones were determined. The melting point of benzoyl peroxide immersed in silicone gum is reported. The aging of silicone gum at 150°C. in air was found to neither increase nor decrease the number of crosslinks.
Ring opening in lactam polymers
Authors: Conix André , Smets G. 
Published: April 2003

AbstractApparent first‐order rate constants and activation energies for the alkaline hydrolysis of polyvinylpyrrolidone, polyactam, vinylpyrrolidone‐maleic acid copolymer, N‐isopropyl‐γ‐valerolactam, butyrolactam, and pyrrolidone‐N‐acetic acid were determined in order to study the influence of structure on the stability of the lactam ring. It was found that the behavior toward alkaline hydrolysis of polyvinylpyrrolidone closely resembles that of its low molecular analogue N‐isopropyl‐γ‐valerolactam. It has been shown that a carboxyl function substituted near the lactam ring has a favorable influence on the ease of hydrolysis. Alkyl substitution on the lactam nitrogen, however, makes the lactam more resistant against hydrolysis.
Non‐Newtonian viscosities in dilute aqueous solutions of sodium carboxymethylcellulose
Authors: Fujita Hiroshi , Homma Terutake 
Published: April 2003

AbstractThe reduced viscosity vs. concentration relation was measured for sodium chloride solutions of sodium carboxymethylcellulose (Na‐CMC of DP ≓ 400 and DE ≓ 0.7) in a range of low concentrations (0.003 to 0.09 g./100 ml.), and the data obtained were analyzed following the procedure of Pals and Hermans. The results confirmed in many aspects findings which had previously been made in the literature, and supplied values of the necessary molecular quantities for our own sample. They indicated that our Na‐CMC molecule was relatively uncoiled even in solutions of high ionic strength. The Huggins slope constant was found to increase approximately linearly with increasing reciprocal of the ionic strength of the solution. Next, the shear dependence of reduced viscosity in dilute solutions of this polyelectrolyte was investigated by the use of a viscometric apparatus which was especially designed for accurate measurements at low shear rates. The shear rate region investigated was from about 50 to 1000 sec.−1. The measurements were made on salt‐free solutions and on solutions of constant ionic strength; in both cases only the regions of sufficiently low concentrations were treated. In the salt‐free solutions the ηsp/C vs. q (q is shear rate) curves showed an upward curvature rather than a quadratic dependence at the limit of shear rate. In this case, the initial slope of each curve increased markedly with increasing dilution. The plots of ηsp/C vs. q for solutions of constant ionic strength (ca. 0.0015 mole/l.) were approximately represented by straight lines within the concentration range investigated. The slope of the straight lines decreased regularly with increasing dilution. Some evidence that these plots have a horizontal initial tangent was observed, but this was never conclusive due to the paucity and inaccuracy of exprimental data at shear rates smaller than 100 sec.−1. The intrinsic viscosity obtained from ηsp/C vs. C curves at constant shear rates for the isoionic system was independent of q. From these findings it was realized how markedly the viscous behavior in dilute solutions of the polyelectrolyte studied was influenced by the addition of small amounts of neutral salt, not only in viscosity value itself but also in its shear rate dependence. Our data and results herein presented were concerned only with a sample of one (average) molecular weight and one degree of etherification. More data, therefore, are needed on samples of varying degrees of polymerization and etherification before a more definite understanding of the problem herein treated is possible.
Diffusion of polyelectrolytes in salt‐free solutions
Authors: Kedem O. , Katchalsky A. 
Published: April 2003

AbstractThe diffusion of polymethacrylic acid in salt‐free aqueous solution has been investigated. At high degrees of ionization the diffusion coefficient is independent of concentration and of the degree of polymerization. However, it depends markedly on the degree of ionization. The hydrodynamic resistance of the polymer ion is calculated from the diffusion coefficients by allowing for the osmotic behavior of the polyelectrolyte in solution. The results, which are discussed, indicate a rodlike shape for the molecule at high degrees of ionization. At zero degree of ionization (polymethacrylic acid in an acid medium) the diffusion coefficient is nearly independent of concentration. It is inversely proportional to the square root of the degree of polymerization, showing that the un‐ionized molecule is not rinsed by the solvent. A quantitative comparison of the diffusion coefficient, with the intrinsic viscosity of the same solution, shows that there is fair agreement with the theory of Kirkwood and Riseman.
Branching in polybutadiene
Authors: Pollock D. J. , Elyash L. J. , DeWitt T. W. 
Published: April 2003

AbstractA detailed study has been made of the intrinsic viscosity‐molecular weight relationship for a polybutadiene prepared at 50°C. and one prepared at 5°C. Original fractions were at least twice refractionated from very dilute solutions in an attempt to obtain fairly sharp distributions. Fox‐Flory K constants are observed to decrease with increasing molecular weight in each case, and the intrinsic viscosity‐molecular weight plots show a curvature. This is interpreted to be a result of branching. A method of plotting the data is proposed which simultaneously yields the K for unbranched material and an estimate of the degree of branching. It is estimated that, in polybutadiene prepared at 50°C., one out of 6500 monomer units is involved in a branch, and that in 5°C. polybutadiene, one out of 10,000.
Hydroxyethyl nylon, a new flexible superpolyamide derivative
Authors: Haas Howard C. , Cohen Saul G. , Oglesby Albert C. , Karlin Estelle R. 
Published: April 2003

AbstractInteresting new derivatives of nylon with unusual properties were prepared by treating nylon with ethylene oxide. These graft copolymers have greatly enhanced flexibility but still retain the high melting character of the original nylon. A hydroxyethyl 6‐6 nylon containing 50% combined ethylene oxide was found to be flexible and useful over a very large temperature range, the polymer having a melting point of 221°C. and an apparent second‐order transition point below −40°C. Analyses, carried out to study the distribution of combined ethylene oxide residues in these materials, indicated a tendency toward limited substitution of the nylon backbone and rather long average polyethylene glycol branch lengths. The distributions of the combined ethylene oxide residues are correlated with the nature of the starting materials. Synthetic methods, analyses, infrared spectra, solubilities, viscosity behavior, melting point and second‐order transition point data, stress‐elongation results, and moisture permeabilities of these materials are reported. The hydroxyethyl derivatives are more hydrophilic than the unsubstituted linear nylons. Hydroxyethyl nylon should also be considerably more stable than Type 8 nylon since it does not contain the labile N‐methoxymethyl linkage. A striking contrast in properties exists between hydroxyethyl nylon and derivatives of nylon prepared in solution under homogeneous conditions. This difference in properties is attributed to a nonrandom distribution of branch sites along the chain in the case of hydroxyethyl nylon. This nonrandomness is due to the heterogeneous nature of the ethylene oxide‐nylon reaction and to the formation of primary hydroxyl groups which are more reactive toward ethylene oxide than the original amide NH groups.
Vinyl polymerization. V. Decomposition of sym‐substituted benzoyl peroxides in the presence of dimethylaniline
Authors: Imoto Minoru , Choe Seuckon 
Published: April 2003

AbstractA study of the rates of the decomposition of benzoyl peroxide and substituted benzoyl peroxides in the presence of dimethylaniline was made. It was proved that the initial rate (v0) of the decomposition could be expressed by the equation v0 = k2P0A0. P0 and A0 are the initial concentrations of peroxide and dimethylaniline, respectively. In the decomposition of substituted benzoyl peroxides, the values of v0 fitted nicely with Hammett's equation. It was confirmed that electron‐attracting substituents accelerated the decomposition and electron‐repelling groups retarded it. As an intermediate of the reaction of benzoyl peroxide with dimethylaniline, a loose complex may be produced by coordination of the electron lone pair in the nitrogen atom with the peroxidic central oxygen atom; through this intermediate, decomposition may occur. Finally, it was assumed that the driving force for the decomposition of benzoyl peroxide was an electrostatic repulsion between the two oxygen atoms of the carbonyl groups (but not of the central peroxidic group).
Fluorine‐containing polymers. II. 1, 1‐dihydroperfluoroalkyl acrylates: Preparation of monomers1
Authors: Codding D. W. , Reid T. S. , Ahlbrecht A. H. , Smith G. H. , Husted D. R. 
Published: April 2003

AbstractAcrylate esters of seven n‐1,1‐dihydroperfluoroalkanols have been synthesized. The esters are: 1,1‐dihydroperfluoroethyl‐; 1,1‐dihydroperfluoropropyl‐; 1,1‐dihydroperfluorobutyl‐; 1,1‐dihydroperfluoropentyl‐; 1,1‐dihydroperfluorohexyl‐; 1,1‐dihydroperfluorooctyl‐; and 1,1‐dihydroperfluorodecyl acrylates. Since these alcohols were difficult to esterify using conventional procedures, acrylyl chloride or acrylic acid plus perfluoroacetic anhydride have been empolyed in this work.
Fluorine‐containing polymers. IV. Polymers of acrylates of fluorine‐containing ether alcohols
Authors: Bovey F. A. , Abere J. F. 
Published: April 2003

AbstractA number of polymers of acrylates of fluorine‐containing ether alcohols were prepared and studied. The side‐chain structures investigated are: CF3CH2OCH2CH2OCO, CF2HCF2OCH2CH2OCO, CF2HCF2(OCH2CH2)2OCO, CF3CF2CF2CH2OCH2CH2OCO,
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and RfOCF2CF2CH2OCO, where Rf equals CF3, CF3CF2, CF3CF2CF2, and CF3CF2CF2CF2. Of these, the last group has glass transition and stiffening temperatures 20–25°C. lower than those of most of the others, together with the small swelling in solvents characteristic of the RfCH2OCO series. It is concluded that polymer behavior, particularly the modulus‐temperature and solubility characteristics, may be very profoundly affected by the nature of the side chains. An interpretation of the behavior of the polyacrylates of the fluorinated ether‐alcohols in terms of increased side‐chain flexibility due to ether “swivel joints” is attractive, but may not be justified.
Fluorine‐containing polymers. V. Light scattering and viscosity study of poly‐1,1‐dihydroperfluorobutyl acrylate
Authors: Rathmann G. B. , Bovey F. A. 
Published: April 2003

AbstractLight scattering measurements in benzotrifluoride indicate that poly‐1,1‐dihydroperfluorobutyl acrylate (poly‐FBA) has been polymerized in emulsion and solution to molecular weights up to 40 million. If the polymerization is carried to high conversion, long chain branching results, presumably by chain transfer to the polymer. Intrinsic viscosities near 1.0 in benzotrifluoride for molecular weights of 10 million are explained largely on the basis of the high monomer molecular weight using Flory's equation relating molecular weight, intrinsic viscosity, and molecular dimensions. From the equation the intrinsic viscosity of a polymer should be expected to decrease roughly as the 3/2 power of the monomer molecular weight, if the increased bulk does not alter the chain flexibility. Long chain branching and the fact that benzotrifluoride is a poor solvent exaggerate the effect. Light scattering and intrinsic viscosity data indicate that the θ temperature for benzotrifluoride (that temperature at which solvent polymer interactions vanish) is only a few degrees below room temperature. Precipitation of poly‐FBA from dilute solutions near 15°C. confirms this fact. Methyl perfluorobutyrate is found to be a better solvent, but the value of the second virial coefficient and the exponent in the equation relating intrinsic viscosity to molecular weight are lower than predicted from swelling data. The freely jointed segment length has been calculated to be 15 carbon atoms, which is larger than reported for other rubbery materials. Short range interactions of the large side chains apparently result in a fair degree of chain stiffness which may be related to the high transition temperature of poly‐FBA relative to its hydrocarbon analog.
Fluorine‐containing polymers. VII. 1,1‐dihydroperfluoroalkyl acrylates: Compounding and properties of vulcanizates
Authors: Stedry P. J. , Abere J. F. , Borders A. M. 
Published: April 2003

AbstractThe homopolymer and butadiene copolymers of 1,1‐dihydroperfluorobutyl acrylate form a new class of vulcanizable elastomers with interesting and useful properties, of which solvent resistance is the most outstanding. The homopolymer (poly‐FBA), vulcanized by means of a polyfunctional amine in the presence of a reinforcing pigment, appears most promising because it offers the following unusual combination of desirable properties: (1) resistance to hydrocarbon solvents; (2) resistance to a variety of lubricants, hydraulic fluids, and similar high boiling liquids at temperatures up to 400°F.; (3) resistance to oxidation by ozone and fuming nitric acid; (4) fair stability and physical properties in air at elevated temperatures. It was shown that many of these properties depend upon compounding recipes and that further improvements can be anticipated.
Light scattering investigation of potato amylopectin
Authors: Witnauer L. P. , Senti F. R. , Stern M. D. 
Published: April 2003

AbstractLight scattering measurements were made on amylopectin prepared from potato starch by two procedures. Potato starch dispersed in water at 90° and fractionated with mixed pentanols gave an amylopectin I having a weight‐average molecular weight of 36 million. Dispersion of starch by autoclaving at 120°, followed by nitrobenzene precipitation of amylose, yielded an amylopectin II with weight‐average molecular weight of 14 million. No evidence was found for dissociation of these amylopectins into smaller units in aqueous solution at concentrations as low as 10−6 g./ml., at elevated temperatures, or in sodium hydroxide solutions. Aggregation of amylopectin II occurred at potassium chloride concentrations above 5 × 10−4 molar. Marked reduction of molecular weight of amylopectin II resulted from treatment under a high rate of shear in a Waring Blendor. Acetylated II (40% acetyl content) was soluble in nitromethane, chloroform, acetone, dioxane, and acetonitrile. In all these solvents the molecular weight, corrected for acetyl, was close to 10 million. No evidence was found for an increase in reciprocal specific turbidity at low concentration which would parallel reported osmotic pressure results. Polydispersity was demonstrated by ultracentrifugal sedimentation patterns of amylopectin II, and by separation of amylopectin I into a series of fractions ranging from 7 to 73 million in molecular weight.
Studies on the validity of the Einstein viscosity law and Stokes' law of sedimentation
Authors: Cheng P. Y. , Schachman H. K. 
Published: April 2003

AbstractUltracentrifugal studies on polystyrene latex particles (PSL) in solutions of different densities prepared either from mixtures of H2O and D2O or from various concentrations of sucrose in water yielded a value, by interpolation, of 1.0520 for the density of solution in which the particles neither sediment nor float. Considerations of these results plus the nature of the particles lead to the conclusion that the partial specific volume of the polystyrene latex particles is (1/1.0520) cc./g., a value in agreement with the bulk specific volume of solid polystyrene. Evidence is presented for PSL to support the view that the effective hydrodynamic volume is equal to the partial specific volume, so that volume fractions can be determined from the partial specific volume and the dry weight concentration. Measurements of the viscosity of suspensions of polystyrene latex particles over a broad concentration range showed that the intrinsic viscosity was 2.5, in confirmation of the theory of Einstein. At concentrations above 2% by volume a square term in concentration, with coefficient about 10, and also a cubic term are needed to satisfy the data. From the partial specific volume of the latex particles and the value of the sedimentation coefficient extrapolated to infinite dilution, a value of 2640 ± 12 A. was calculated for the diameter of the particles from Stokes' law. This value is in excellent agreement with values obtained by electron microscopy, light scattering, and low angle x‐ray scattering. This agreement amounts to a satisfactory test of Stokes' law for particles not much larger than some of the viruses. Studies of the dependence of sedimentation coefficient on concentration indicate that existing theories are not completely satisfactory and that the influence of backward flow of liquid during the sedimentation of the solute particles is appreciable.