bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular dimensions in relation to intrinsic viscosities
Authors: Newman Seymour , Krigbaum William R. , Laugier Claude , Flory Paul J. 
Published: April 2003

AbstractRoot‐mean‐square end‐to‐end dimensions (r2)1/2 and molecular weights M have been determined from light scattering studies carried out on a series of fractions of poly‐(acrylic acid) in dioxane (θ point, 30°C.), on two polyisobutylene fractions in cyclohexane and in ethyl n‐caprylate (θ point, 22°C.), and on a single poly‐(methyl methacrylate) fraction in acetone. Intrinsic viscosities of the various polymers measured in these same solvents at the same temperature (30°C.) support the relationship [η] = Φ(r2)3/2/M, where Φ is a constant independent of molecular weight and solvent type and (according to the data herein reported) has the approximate value 2.2 × 1021. The θ points, representing the temperatures at which ideal behavior prevails, were determined for the two poor solvent–polymer systems by extrapolation of critical consolute temperatures to M = ∞. The intrinsic viscosity of poly‐(acrylic acid) in dioxane at 30°C. (the θ point) is given by [η] = 0.85 × 10−3M1/2; the value of the constant approximates those for nonpolar polymers.The influence of molecular weight heterogeneity on the fundamental relationship of the intrinsic viscosity to (r23/2/M) is analyzed, and it is shown that the true value of the universal parameter Φ will be greater than the apparent value deduced in the foregoing manner without correction for the heterogeneity of the polymer fraction. For a fraction possessing a relatively sharp distribution as denoted by 〈M〉w/〈M〉n = 1.15. the magnitude of this correction may be as high as 20%.
Use of deuterium to investigate extent of branching in polystyrene
Authors: Wall Leo A. , Brown D. W. 
Published: April 2003

AbstractThe extent of branching in polystyrene is attributed to a polymer transfer step occurring during polymerization. In this process a radical abstracts a hydrogen atom from along a chain which then adds monomer at the site of the abstraction. The rate of this process should be decreased if the hydrogen is replaced by deuterium, and consequently deuterated monomers should polymerize to form polymers less branched than those from the nondeuterated monomer. Polymers of α‐ and β‐deuterostyrene were synthesized and thier intrinsic viscosity and molecular weight by light scattering determined. In the case of the α‐deuterostyrene, the polymer was also fractionated and measurements were made on the fractions. The data for the deuterated styrenes fit quite closely the same relationships as a normal styrene sample prepared simultaneously and under the same conditions, i.e., 70°C. and without catalyst. The results indicate, therefore, that branching is quite small in polystyrene prepared under such typical conditions. A check of the isotope effect on the transfer process was made utilizing S‐deuterobutyl mercaptan. A value of 4.0 was obtained at 60°C. for the relative rate of transfer with butyl mercaptan to that for the deuterated mercaptan.
Multiple dispersion regions in rigid polymeric systems
Authors: Buchdahl Rolf , Nielsen Lawrence E. 
Published: April 2003

AbstractIt is shown how chemical and colloidal heterogeneity can result in multiple dispersion regions of the mechanical or electrical loss factor as a function of temperature. Heterogeneity can be produced in several ways: (a) mechanical blending (mixing) of certain polymers, (b) non‐uniform copolymerization, (c) block or graft polymerization, (d) external plasticization, and (e) certain types of molecular weight distribution. Specific examples are given to demonstrate the effect.
Unusual orientation phenomena in polyethylene interpreted in terms of the morphology
Authors: Keller A. 
Published: April 2003

AbstractIn the first part of the paper various orientation phenomena of the drawing‐relaxation behavior are interpreted in terms of the changes occurring within the submicroscopic helices which form the spherulites. Not only drawing and relaxation but also the redrawing of the relaxed samples were followed, and it was shown that the observed anomalous orientation effects cannot be described in terms of tilts of planes with simple indices. However, by considering also the possible shapes of the submicroscopic units these orientation effects can be visualized. In the second part a new general type of orientation, the “row orientation” is introduced. This arises when crystallization takes place while the melt is flowing. Flow produces lines of high nucleus density, leading to growth of the crystallites in all directions perpendicular to the direction of drawing. This results in elongated aggregates of helices, and the alignment of these complex units produces a unique type of orientation which has been established from various angles.
Infrared study of oxidation of elastomers
Authors: Field J. E. , Woodford D. E. , Gehman S. D. 
Published: April 2003

AbstractInfrared absorption spectra were used to study the structural changes resulting from oxidation in a number of unvulcanized, purified polymers under a variety of experimental conditions. The results showed that as oxidation progressed, the structural changes which were detected were qualitatively the same for all of the polymers under all of these experimental conditions. Correlation of volumetric measurements with spectral data indicated that considerably more oxygen was absorbed by the polymer samples before structural changes could be detected than the minimum amount required for the initial detection of the hydroxyl and carbonyl structures. From the interpretation of information from the absorption spectrum, it is believed that the structural evidence is in substantial agreement with current theories on autoxidation. Although the initial hydroperoxide formation is not observed in the spectrum, it is quite probable that this reaction takes place with almost immediate decomposition which results in a net hydroperoxide concentration so low as to make infrared methods insensitive for its detection. Correlation of physical properties with structural studies indicate that little change in these properties take place until the hydroxyl and carbonyl structures become evident in the infrared spectrum.
Interaction of polydimethylsiloxanes with swelling agents
Authors: Bueche A. M. 
Published: April 2003

AbstractThe swelling of a crosslinked polydimethylsiloxane in a number of swelling agents has been measured. Values of the solvent‐polymer interaction parameter, χ1, have been computed and have been compared with the solubility parameters of the swelling agents and with other data from the literature. The magnitude of the solubility parameter of the polymer depends markedly on the swelling agents and method used for its estimation. The values reported here range from 7.7 to 5.03.
Investigation of unusual orientation in polyethylene by infrared spectroscopy
Authors: Keller A. , Sandeman I. 
Published: April 2003

AbstractA quantitative analysis of the 725 cm.−1 doublet in the infrared spectrum of polyethylene is given and used to check the “row” model of polyethylene, as it naturally crystallizes from drawn melt. This analysis depends on a new interpretation of the 725 cm.−1 doublet, according to which the 730 cm.−1 component has its transition moment along the a crystallographic axis, and the 720 cm.−1 component along the b axis. The amorphous polymer gives only a band at 720 cm.−1. The analysis in certain cases enables the amount and orientation of the amorphous component of the polymer to be determined. From similar considerations, variations in the relative intensity of the two peaks in the course of drawing unoriented polyethylene are explained.
Phase separation in solutions of vinyl polymers
Authors: Kern R. J. , Slocombe R. J. 
Published: April 2003

AbstractWhen polymers of two different chemical species are dissolved in a common solvent the resulting solution usually separates into two phases. No obvious relation between phase separation and chemical nature of the monomeric units was observed. Solute molecular weight, temperature, and nature of the solvent were shown to be factors in determining the course of phase separation. A concept of phase separation is suggested which involves low entropy of mixing, greater attraction between like than unlike species of solute, and density differences between solvated polymer molecules.
A kinetic interpretation of the rheological behavior of high polymers
Authors: Furukawa Junji 
Published: April 2003

AbstractA chemical kinetic interpretation of the rheological behavior of high polymers has been proposed, in which the polar force of segments locks the adjacent segments in neighboring molecules in a similar way to crosslinking in vulcanized rubber. The change of such a crosslink caused by the thermal motion of segments and by external stress on the sample gives rise to rheological phenomena, such as the relaxation of stress or strain. The elasticity or viscosity of high polymers is related to the equilibrium crosslinkage which is affected not only by the temperature change but also by external stress. The structural viscosity, the yield point, or the effect of solvent on elasticity or on viscosity can also be understood according to this interpretation. The theoretical treatment gives many equations previously found in experiments: the equation for relaxation of deformation or stress, i.e., the four‐element‐model equation, the Dienes' equation with respect to the temperature dependence of elasticity of polyvinyl chloride, or Rabinovitch's equation for structural viscosity.
The pyrolysis of p‐xylene
Authors: Schaefgen John R. 
Published: April 2003

AbstractA quantitative study of the pyrolysis of p‐xylene at temperatures from 795° to 920° at low pressures has been made using a flow system at low contact times. A mechanism is postulated to account for the principal products. The primary rate controlling reactions are the dissociation of either a CH bond in the methyl side chain or a CC bond from the ring to the methyl group, the activation energies of which are 79 and 82 kcal., respectively. Evidence is presented for the existence of the intermediate p‐xylylene molecule, and for its formation by disproportionation from the initially formed p‐methylbenzyl radicals. The copolymerization of p‐xylylene with maleic anhydride or chloroprene is described.
Polymer chain dimensions in mixed‐solvent media
Authors: Shultz A. R. , Flory P. J. 
Published: April 2003

AbstractThe equilibrium between a linear polymer molecule and a binary solvent mixture in which it is immersed has been treated. An equation has been derived relating the resulting molecular expansion to the thermodynamic parameters for the ternary system and to the solvent composition. Intrinsic viscosity measurements are reported for polystyrene fractions in three mixed‐solvent systems: methyl ethyl ketone‐methanol, carbon tetrachloride‐cyclohexane, and benzene‐cyclohexane. Intrinsic viscosities measured for polystyrene fractions in critical consolute mixtures agree with those found in single poor solvents at the analogous Theta points. Intrinsic viscosities have been measured over ranges of mixed‐solvent composition for the second and third solvent mixtures mentioned. Poor agreement with theory is observed for the former, but the more extensive measurements in benzene‐cyclohexane mixtures agree very well with theoretically calculated intrinsic viscosities.
Sorption of nitrogen dioxide by cellulose acetate
Authors: Myles William J. , Reiss Howard 
Published: April 2003

AbstractSorption of NO2 by cellulose acetate proceeds by a process of solution, diffusion, and reaction governed by Henry's law, Fick's law, and first order kinetics with respect to the consumption of NO2. It appears as though water is the primary substrate with which NO2 reacts in the acetate film. The pseudo‐unimolecular rate constant for films conditioned at 50% RH seems to be about 10 ± 5 × 10−3 sec.−1. The solubility of NO2 in dry film increases with increasing degree of acetylation. With the present data the diffusion coefficient and solubility in moist films cannot be determined separately, but only jointly as a parameter involving the product of one by the square of the other. Improved experiments designed to yield precision during the later stages of the sorption process should yield separate values of the two constants.
The degradation of cellulose by ionizing radiation
Authors: Charlesby A. 
Published: April 2003

AbstractWhen subjected to the effect of ionizing radiation, such as atomic pile radiation or gamma radiation, cellulose is rapidly degraded into a powdery material. A theoretical treatment shows that if the effect of radiation is to cause fracture at random in the main chain, the relation between intrinsic viscosity [η] and radiation dose R should be of the form:

where R0 is a “virtual” radiation dose needed to produce the initial number‐average molecular weight from a chain of infinite molecular weight. The published data of Saeman, Millett, and Lawton have been used to verify this formula, which leads to a relationship between [η] in cupriethylenediamine and viscosity‐average molecular weight Mv:

with α = 0.71. The constant K has been evaluated by comparison with data given by Gralen, but is less accurately known. It is deduced that one million roentgen results in fracture of 0.16% of the monomer units in the main chain. The decomposition of carbohydrates under radiation, which occurs at the same time as main chain fracture, can be explained on the assumption that approximately one monomer unit is decomposed per main chain fracture. The study of intrinsic viscosity of irradiated polymers appears to offer an accurate means of evaluating α in the usual formula for intrinsic viscosity [η] = KMα.
Vinyl polymerization. III. Polymerization of acenaphthylene
Authors: Imoto Minoru , Takemoto Kiichi 
Published: April 2003

AbstractPolymerization of acenaphthylene by boron trifluoride‐ether complex as catalyst was carried out in benzene solution of various concentrations of the catalyst over a range of temperatures from 20 to 50°C. Over‐all rate of the polymerization was found to be of the first order both for the initial concentration of the monomer and for that of the catalyst:

Activation energy required in the reaction was calculated to be 12.5 kcal./mole, and the molecular weight of polymers measured by the Gee osmometer was shown to be of the same order as found by previous workers.
Absorption and swelling by nitrocellulose fibers and films in binary solvent–hexane mixtures
Authors: Moore W. R. 
Published: April 2003

AbstractAbsorption of solvent and swelling by nitrocellulose fibers and films, in binary solventhexane mixtures of varying concentration and involving ketones, acetates, and phthalates, have been compared. Equilibrium is less rapidly attained with films. With solvents of smaller molecular size the equilibrium absorption of fibers and films, at a given concentration, is the same, suggesting that all regions of the nitrocellulose are accessible to such solvents. With solvents of larger molecular size lower equilibrium absorption values are obtained with films, suggesting that only certain regions are accessible to these solvents and such accessibility is less in films. Where absorption values are similar, swelling of films and fibers are comparable and similar modes of solution are observed. The assumption that no hexane is absorbed appears to be justified at lower solvent concentrations, but at higher concentrations the mixture in equilibrium with the nitrocellulose may be imbibed. Assuming such imbibition, the relationship between swelling or solvent power and cohesive energy density of solvent is interpreted in terms of interaction between solvated polymer and mixture.
Studies of the ethylenediamine‐cellulose complex. I. Decomposition of the complex by solvents
Authors: Loeb Leopold , Segal Leon 
Published: April 2003

AbstractThe ethylenediamine‐cellulose complex, previously described by Trogus and Hess, has been reinvestigated with regard to its stability toward a series of solvents and to the differences in the fine structure of the cellulose remaining after its decomposition. It is shown that nonpolar solvents which do not contain oxygen have little effect on the complex; they do not reduce the diamine content or alter its crystal structure. On the other hand, it has been found that polar, oxygen‐containing solvents almost completely remove the diamine and, in general, cause a reconversion of the crystal structure to the cellulose I crystalline modifications. The nature of the fine structure of the cellulose remaining after decomposition of the complex is discussed in relation to the directive or orienting influence of the solvent used for the decomposition. It is shown empirically that the directive influence of a solvent is related to its polarity and to the temperature at which the decomposition is effected.
Structure of polysiloxanes: Influence of solvent on size and polymer‐solvent interaction of linear polydimethylsiloxanes
Authors: Price Fraser P. , Bianchi Joseph P. 
Published: April 2003

AbstractMolecular weight, sizes, and second virial corfficients of a linear polydimethylsiloxane polymer (MW = 4.57 × 105) in mixtures of toluene‐diethylphthalate have been determined by light scattering. Intrinsic viscosities have also been measured in the same mixed solvents. As expected, as the diethylphthalate concentration was increased the molecules contracted and the second virial coefficients became more negative. The data were used to attempt to decide between two current theories relating these quantities. No choice could be made. It was found that the calculated values of Flory's universal constant, φ, were much smaller than those usually obtained. It is proposed that this is due to an abnormally broad molecular weight distribution in the polysiloxane.
Ultrasonic degradation of cellulose nitrate: Relation between initial and final average and distribution of DP
Authors: Thomas Berwyn B. , Alexander W. J. 
Published: April 2003

AbstractCellulose nitrates of average DP 130 to 2400 and of various DP distributions were degraded in ethyl acetate solutions by ultrasonic energy at 400 kilocycles. A method of comparing degradation rates of samples degraded at different concentrations is described. The degrees of degradation found were in accord with the theory of Schmid and co‐workers, and the minimum degradable chain length was calculated to be 980 DP in this system. Where compared with degradation by alkaline aging, ultrasonic degradation gave a much more uniform chain length distribution. After ultrasonic treatment, 60% of the sample was of DP 700 to 1200, while the alkaline aged sample had less than 40% in this same range and a much larger amount of short chain length material. The results do not give any indication of the presence of any physically or mechanically weak chain links at any interval near 500 DP.
Influence of molecular weight and degree of crosslinking on the specific volume and glass temperature of polymers
Authors: Fox T. G. , Loshaek S. 
Published: April 2003

AbstractOn the basis of simple assumptions, equations are derived for predicting the specific volume‐temperature‐molecular weight (v‐T‐M) relationships for a homologous series of polymers from the v‐T curves for the monomer and the polymer of infinite molecular weight. Analogous v‐T‐ρ relationships (where ρ is the degree of crosslinking) are similarly obtained. The result, that v decreases linearly with decreasing 1/M and with increasing ρ, conforms with the picture that either the removal of two chain ends (as M increases) or the introduction of a crosslinkage involves, between two polymer segments, the exchange of a van der Waals bond for a shorter covalent bond. The validity of these equations is illustrated by comparison with the observed data for polymers covering a wide range in M, T, and chemical type. For several polymer series the extrapolated value of v at 0°K (v0) is the same for all members of the series, indicating that at this temperature the average length of the van der Waals and covalent bonds between polymer segments are the same. Assuming that the form of the linear relationship observed for polystyrene between the specific volume (vg) at the glass temperature and the value (Tg) of the latter is valid for other polymer series, equations are derived which predict Tg as a function of M from the limiting value of the glass temperature for a chain of infinite length, and from the v‐T curves in the liquid state for the monomer and for the polymer of M = ∞. Analogous Tg‐ρ relationships are similarly obtained. According to these equations, a linear relationship between 1/Tg and 1/M should be obtained, which reduces at high M to a linear dependence of Tg on 1/M. Similarly, a linear dependence of Tg on ρ is predicted at low ρ. These predictions are in satisfactory agreement with data on polystyrene fractions and on crosslinked copolymers of styrene with divinylbenzene.The conclusion that Tg for polystyrenes represent a state of iso‐free volume irrespective of M is shown to be an approximation that is valid, within experimental error, only for large values of M.
Crosslinked polymers. II. Glass temperatures of copolymers of methyl methacrylate and glycol dimethacrylates
Authors: Loshaek S. 
Published: April 2003

AbstractGlass temperatures are given for copolymers containing methyl methacrylate and from 0 to 100% of each of the dimethacrylates of ethylene glycol (EGDMA), decamethylene glycol (DGDMA), and 2‐ethyl‐2‐butylpropanediol‐1,3 (2‐E‐2‐B‐PDMA), and for copolymers containing from 0 to 17 mole per cent of the dimethacrylate of 2,2‐dimethylpropanediol (2‐2‐D‐PDMA). The relation between Tg and the mole fraction of dimethacrylate in the copolymers is complex, maxima being observed for the DGDMA and 2‐E‐2‐B‐PDMA copolymers. This unexpected behavior is interpreted on the basis that the introduction of crosslinkages by copolymerization of a vinyl with a divinyl monomer affects Tg by concomitant changes in the average copolymer composition (“copolymer effect”) and the degree of crosslinking (“crosslinking effect”). The copolymer effect is obtained separately for the MMA‐EGDMA copolymers from the observed Tg‐composition relation for copolymers of MMA with ethylene glycol monomethacrylate, monoisobutyrate. The crosslinking effect per se is then calculated on the basis of the assumption that the copolymer and crosslinking effects are independent and additive. For the EGDMA copolymers, it is found that the effect of crosslinking alone causes Tg to increase linearly with an increase in the number (ρ) of crosslinks per gram of polymer, and that the proportionality constant is of the same order of magnitude as that observed in the preceding paper for the styrene‐divinylbenzene copolymers. This observed Tg‐ρ relation is in semiquantitative agreement with the equations of the preceding paper, and lends support to the concept of additivity and independence of the copolymer and crosslinking effects upon which the observations are based. The results on the MMA‐EGDMA copolymers, together with the less extensive data on the other copolymers, indicate that the magnitude of the increase in Tg for each crosslink introduced is essentially independent of the structure of the crosslinker.
Rate of thermal diffusion of polymer molecules in solution
Authors: Hoffman John D. , Zimm Bruno H. 
Published: April 2003

AbstractMeasurements of the thermal diffusion constant of polystyrene in toluene and butyl acetate solutions have been made. Direct observation of a moving boundary was used. There is a small change of thermal diffusion constant with molecular weight, but it is doubtful that it could be used for analytical purposes. The results for polystyrene in toluene have been compared with those obtained by Debye and Bueche with a convection‐type column.