bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Molecular Weight of High Polymers by Measurement of Osmotic Pressures at Low Concentrations
Authors: Gilbert G. A. , Graff‐Baker C. , Greenwood C. T.
Published: April 2003

An equilibrium osmometer for the measurement of very low osmotic pressures has been designed. It is constructed of metal and employs a large horizontal membrane. A rapid approach to equilibrium is obtained by the use of a fine capillary and a bacterial cellulose membrane (Masson and Melville) in conjunction with complete thermostatting. To avoid displacement, the membrane is stretched in a frame and held over a grooved domed support of the Carter‐Record type. Details of procedure, including concentration estimation and the preparation of membranes, are given.

Measurements of the osmotic pressure of a fractionated sample of polystyrene, of molecular weight approximately one million, have served to determine the precision of the osmometer. At a pressure of 0.026 cm. of chloroform, the standard deviation was found to be 0.002 cm. The importance of correcting for the density of the solution, when measuring high molecular weights, is discussed.
Propriétés de dilatation thermique des polyamides
Authors: Ecochard F.
Published: April 2003

A description is given for a simple method of measuring the expansion coefficient of plastic material, and other quantities, derived thereof (density of the liquid sample). A practical application is given in the case of some polyamides. This study makes it possible to show the presence of a maximum in the expansion curve; that maximum is probably related with the appearance, under thermal agitation, of a new degree of freedom of the molecules.
Sulfonation of natural rubber
Authors: Van Amerongen G. J.
Published: April 2003

The sulfonation reaction of rubber with SO2 is discussed. It proves to be a chain reaction which can be catalyzed by various compounds. Diazoamino compounds, hydroperoxides, some metal nitrates and nitrites, NO, and NO2 are found to be catalytically active. The activity of these substances varies considerably; the hydroperoxides NO and NO2 inducing immediate reaction; the diazoamino compounds within a few minutes; and the metal nitrates, such as LiNO3, in several hours.

The reaction has a ceiling temperature at about 35 to 40°C., above which no reaction takes place. The properties of the reaction products are governed by the amount of SO2 bound and vary from rubbery to horny, and ultimately brittle and resinlike. Products of moderate SO2 content swell in organic solvents; products of high SO2 content dissolve only in concentrated H2SO4 of HNO3. The workability of the products is rather poor
Emulsion polymerization of styrene. I. A reproducible system
Authors: Yang P. T. , Guile R. L.
Published: April 2003

Excellent reproducibility of an emulsion polymerization of styrene has been obtained in a nitrogen atmosphere and a technique and apparatus have been described to obtain this reproducibility. The rate of polymerization for this system has been shown to be proportional to the square root of the catalyst concentration and to increase with higher catalyst concentrations. Average molecular weights were higher with higher concentration of catalyst within the catalyst concentrations studied and polymerization occurred without significant pH changes.

In contrast, reproducibility of the emulsion polymerization in air atmosphere was unsatisfactory. The presence of air (oxygen) increased the induction period, decreased the rate of polymerization and decreased the average molecular weight of the polymer. Since the time necessary for polymerization was increased, the decrease in pH was considerable during the polymerization.
Swelling of polyvinyl alcohol in water
Authors: Priest W. J.
Published: April 2003

Swelling and solubility characteristics of polyvinyl alcohol and polyvinyl alcohol–acetate copolymers in liquid water have been examined. For a given species, swellings are found to be variable in a continuum of metastable states depending on the previous history of the polymer. Changes in swelling are induced in a predictable manner by treatments such as humidification. Changes are interpreted in terms of cumulative secondary bond cross‐linkages arising from the development of microcrystalline regions within the gel.
Polyalkylene sulfides. VIII. Polymers from 4‐vinylcyclohexene
Authors: Marvel C. S. , Roberts C. W.
Published: April 2003

Pure 4‐vinylcyclohexene and hexamethylenedithiol react under a variety of conditions to produce a polymer which has factice‐like properties. The polymers with the highest inherent viscosity were prepared in MP‐189‐EF emulsion at a pH of 4 with a persulfate–bisulfite–copper sulfate initiator. The polymers are readily cross‐linked, and if dried without careful removal of initiator solution, they show properties of vulcanized factice samples. Bisazoisobutyronitrile, a cumene hydroperoxide–ferrous pyrophosphate system, and a ceric sulfate–bisulfite copper system have also been used to initiate this polymerization reaction.
Copolymerization of butadiene and styrene in the oxygen–1‐alkanesulfinic acid system
Authors: Marvel C. S. , Meinhardt N. A.
Published: April 2003

The copolymerization of butadiene and styrene in an alkanesulfonic acid emulsion with air as the oxidizing agent and higher alkanesulfinic acids as oil‐soluble reducing agents has been studied. Dodecyl mercaptan and ferric salts are needed to make this recipe function well. The optimum pH for rapid polymerization was found to vary with the different alkanesulfinic acids (C8 to C18 in the even‐numbered straight‐chain series). Tetradecanesulfinic acid is the most active reducing activator in this series. The conversions with butadiene and styrene are about 75–80% at 30° in six hours and these copolymers have normal solubility and inherent viscosities.
The degradation of long‐chain molecules by ultrasonic waves. II. Degradation of polystyrene
Authors: Jellinek H. H. G. , White G.
Published: April 2003

The degradation by ultrasonic waves of a homogeneous polystyrene sample has been studied. The degradation does not proceed to the monomer but ceases at a definite intermediate chain length. A rate constant has been derived. The experimental size distributions of the polymer at various stages of the degradation have been determined and compared with size distributions derived from the theory of ultrasonic degradation. Satisfactory agreement has been found between experiment and theory for the main features of the degradation.
The degradation of long‐chain molecules by ultrasonic waves. IV. The dependence of rate constant on concentration for polystyrene
Authors: Jellinek H. H. G. , White G.
Published: April 2003

The dependence of the rate constant on concentration in the degradation by ultrasonic waves of polystyrene in benzene has been determined. At fairly high ultrasonic intensities the overall rate constant increases with decreasing concentration but appears to tend to a maximum. This maximum has been located at a reduced ultrasonic intensity for a particular sample of polystyrene and it is shown to occur at a concentration when the chains are highly entangled.
Studies in copolymerization. Kinetics of the copolymerization of styrene and p‐methoxystyrene
Authors: Bonsall E. P. , Valentine L. , Melville H. W.
Published: April 2003

The copolymerization of styrene and p‐methoxystyrene at 60°C., catalyzed by the thermal decomposition of 2‐azobisisobutyronitrile, has been studied. A combination of rate and molecular weight data has shown that δ = (kt1/2/kp) = 25, kf/kp = 1.1 X 10−4 for styrene and δ = 21, kf/kp = 0.74 X 10−4 for p‐methoxystyrene. The over‐all energy of activation for styrene is shown to be Ep − 1/2Et = 6.2 kcal. The rate of initiation (I) of these monomers does not correspond with the rate of production of free radicals from the catalyst, e.g., experimentally, I = 3.3 X 10−8 and I = 2.1 X 10−8 mole/liter/sec. for styrene and p‐methoxystyrene, respectively, at a catalyst concentration of 1 g./liter. The rate calculated from the rate of fission of the catalyst is 12.2 X 10−8 mole/liter/sec. The rates of copolymerization and initiation have been measured for various monomer mixtures; the former was practically independent of monomer composition but the latter varied directly with monomer composition. A value of ϕ = 1[ϕ = k/(kk)1/2] satisfies the experimental results, in agreement with the theory previously presented, i.e., that ϕ2 = (A212/A11A22)(1/r1r2). The validity and usefulness of this theory are discussed in the light of available data and criticisms, and it is shown that both entropy and polar effects play important roles in cross‐termination reactions.
Quantitative x‐ray studies of order in amorphous and crystalline polymers. Quantitative x‐ray determination of crystallinity in polyethylene
Authors: Krimm Samuel , Tobolsky Arthur V.
Published: April 2003

Various quantitative scattering relationships for polymers have been examined experimentally in order to test their validity as assumptions in the x‐ray determination of crystallinity. These are (a) the proportionality between the scattered intensity and the pt value of the specimen (p is the density and t the thickness of the material), (b) the relationship between equal pt values for two different specimens of the same material and the corresponding scattering masses in the beam, (c) the scattering from equal masses of a polymer in the amorphous or crystalline states, and (d) the values of the total scattered intensity from equal masses of different polymers. It has been demonstrated, at least in the case of polyethylene, that the percentage of crystalline material in a polycrystalline polymer can be determined quantitatively by means of x‐ray diffraction methods. The method used in this study, viz., a comparison of the amorphous scattering from the sample with that from a completely amorphous sample, has been applied to an investigation of the temperature variation of crystallinity in unstretched and stretched polyethylene. The comparison between the x‐ray and density results for the case of the unstretched material has been pointed out. The technique has also permitted a determination of the orientation of the crystallites. By means of these methods, it has been shown that the x‐ray diffraction results are in essential agreement with previous stress‐birefringence data on stretched polyethylene; and that the nature of the stretchng process is different at high and at low elongations.
On the dissociation equilibrium of high‐molecular weak electrolytes
Authors: Kagawa Ikumi , Katsuura Kakuji
Published: April 2003

Using the cellulose glycolic acid ethers of various etherification degrees as a sample of high‐molecular weak electrolytes, investigations were carried out on some problems on the dissociation equilibrium, such as the influence of sample concentration, distribution density of electrolyte radicals, the salt effect, and the effect of neutralization reagents. The experimental data were treated by means of the modified Kern's dissociation formula (1) and Kagawa's formula (2).

The results obtained were discussed with Kagawa's opinion on the fixation of counterions.
Some aspects of the motion of chain segments in plasticized polyvinyl chloride. II. Tensile creep of plasticized polyvinyl chloride
Authors: Dyson A.
Published: April 2003

The relations between stress, strain. and time in the tensile creep under constant load of polyvinyl chloride plasticized with dioctyl phthalate have been studied experimentally over a range of temperatures and compositions. It is concluded that existing theories are not adequate to deal with large strains, nonequilibrium conditions, and a distribution of relaxation times. The variables stress, strain, and time may be separated at low loads for “soft” compositions but not for “hard” compositions.
Elastoviscous properties of polyisobutylene. IV. Relaxation time spectrum and calculation of bulk viscosity
Authors: Andrews R. D. , Tobolsky A. V.
Published: April 2003

The elastoviscous behavior of polyisobutylene may be interpreted in terms of a mechanical model consisting of a distribution of Maxwell elements connected in parallel. The structure of this “generalized Maxwell model” is specified by the distribution of relaxation times of the component elements. The relaxation of stress curve of the material is directly related to the distribution of relaxation times, and general expressions for the bulk viscosities (tensile and shear) of such a system in terms of the distribution of relaxation times are readily obtained.

A simple “box distribution” of relaxation times is described which can be used to approximate the relaxation behavior of polyisobutylene at the long‐time end of the relaxation time spectrum, and in terms of which the expressions for bulk viscosity reduce to very simple form. The parameters specifying this distribution may be determined from experimental relaxation curves by a simple graphical method. Values of these parameters as a functions of molecular weight and temperature are computed, by use of these data. It is shown that bulk viscosity values calculated from relaxation data by this method are in good agreement with experimental values for both tensile and shear deformations, and for both unfractionated and fractionated polymers. Measurements of viscosity and of relaxation of stress can thus be directly correlated, and could be used in combination to characterize elastoviscous properties over wide ranges of molecular weight and temperature.
A study of the oxidative degradation of polyvinyl formal
Authors: Beachell Harold C. , Fotis Peter , Hucks Janet
Published: April 2003

The oxidative degradation of polyvinyl formal at temperatures of 150°C. and above has been followed by changes in the infrared spectrum in conjunction with the loss in weight and color development. It is a complex process of cross‐linking and oxidation, rather than one of depolymerization. The infrared spectrum shows rapid development of carbonyl and ethylenic groups in the molecule, accompanied by loss of carbon‐hydrogen and formal groups.

A free radical mechanism for the rupture of the formal ring is proposed, which explains the loss of formaldehyde and water from the polymeric molecule and the production of carbonyl and ethylenic groups in the chain that are capable of producing color.

The stability of polyvinyl formals of various compositions is compared and the effects of residual acetate and alcohol groups on the rate of degradation are discussed.

Several catalysts and inhibitors for the process are also presented.
Ripening reactions of viscose
Authors: Kagawa Ikumi , Kobayashi Haruo
Published: April 2003

From the same standpoint as Kagawa and Katsuura's opinion on the hydrolysis of cellulose sulfate, the authors argue that the spontaneous decomposition of cellulose xanthate in the course of ripening is ripening is wholly due to the alkali saponification which arises at the unionized ester‐group:
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Taking the characteristic features of the electrolytic dissociation of polymeric electrolytes into consideration, the authors derive theoretically the fomula of saponification velocity:

The experimental results agree satisfactorily with this formula when n = 2. The authors also examine experimentally the variation in composition of viscose with especial reference to Na2S and Na2CS3 as the salt components, and explained the secondary reactions in ripening presumably as being caused by the successive decomposition of the primary decomposition product of xanthate, viz., dithiocarbonate, by the following mechanism, in which much stress is laid upon the ionization of reaction components:
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Observations on small‐angle interference maxima in synthetic organic polymers
Authors: Meibohm E. P. H. , Smith A. F.
Published: April 2003

Off‐meridian small‐angle x‐ray interference maxima and multiple orders of small‐angle interference maxima have been observed for certain synthetic high polymer fibers including polythene, polyamides, polyethylene terephthalate, and polyvinyl alcohol. The observations indicate that the ordering of the structures responsible for small‐angle diffraction may be two‐ or three‐dimensional rather than one‐dimensional and that such ordering must extend over larger volumes of space than previously published data would indicate. The fibers must be given relaxation treatments to form the structures that result in small‐angle maxima except for polythene in which they appear merely on orientation. The relaxation treatments increase the crystallite size as shown by large‐angle pictures and modify the positions and shapes of the small‐angle maxima. An increase in the degree of relaxation increases the intensity of the interference and increases the magnitude of the interplanar spacing except for polyvinyl alcohol, in which the interplanar spacing is not affected. Samples of 66 nylon, which varied in molecular weight from 26,000 to 200,000 gave identical small‐angle interference patterns within the limits of accuracy.
A simple method of measuring the moment of disappearance of soap micelles during polymerization in emulsion
Authors: Klaassens K. H. , Bakker J. , Schoot C. J. , Goorissen J.
Published: April 2003

In this paper a simple method is described for determining the moment of disappearance of soap micelles during the emulsion polymerization of styrene by measuring the electrolytic conductivity during the polymerization.
Adhesion. IV. The meaning of tack temperature
Authors: McLaren A. D. , Li T. T. , Rager Robert , Mark H.
Published: April 2003

Heretofore it has been assumed that, under the same experimental conditions of time and magnitude of applied pressure, all amorphous polymers have equal viscosities at their tack temperatures. Further evidence is obtained with a number of polymers in support of the theory. As a nonequilibrium property characterizing high polymers, tack temperature thus belongs in a category with brittle points, second‐order transition points, and softening temperatures.
The p‐phenylene linkage in linear high polymers: Some structure–property relationships
Authors: Edgar Owen B. , Hill Rowland
Published: April 2003

The high crystallite melting point of polyethylene terephthalate (Terylene) compared with the melting points of the aliphatic polyesters emphasizes the significance of the p‐phenylene linkage as an important factor determining polymer properties. A consideration of other polymer structures containing the p‐phenylene linkage shows that its influence is independent of any polar groups which may be present. X‐ray examination of the crystallite structure of polyethylene terephthalate and related substances has revealed no evidence of strong intermolecular forces.

From a study of co‐polyesters based upon polyethylene terephthalate with aliphatic dibasic acids it is shown that the melting point of compositions containing more than 40 mole per cent of ethylene terephthalate is essentially independent of the aliphatic di‐basic acid employed. The Flory relationship between crystallite melting point and mole fraction of the units forming the crystallites shows fair agreement with the results obtained. The calculated latent heat of fusion of polyethylene terephthalate approaches closely to that of the corresponding aliphatic polyesters, and suggests that the high melting point induced by the p‐phenylene linkage is due to chain rigidity rather than to strong interchain attraction.

This rigidity is consistent with the second order transition temperatures of such polyesters. It is shown that second order transition temperature is a linear function of the number of p‐phenylene linkages per unit chain length. The p‐phenylene linkage reduces the possibilities of change of shape available to a given length of chain, so accounting for the low entropy of crystallization and high melting point of polyethylene terephthalate.

Evidence is advanced for the isomorphism of adipyl and terephthalyl linkages in linear polyamides. The absence of isomorphism in polyethylene adipate/terephthalate copolymers is ascribed to the weakness of the interchain forces.
Some types of organic high polymers and permutoids provided with active groups: Their synthesis, optical properties, and reactivity
Authors: Lautsch W. , Broser W. , Rothkegel W. , Biedermann W. , Doering U. , Zoschke H.
Published: April 2003

The synthesis and the properties of permutoids with ionic active groups and the kinetics of the decomposition of diazoacetic ester and of nitrosomethylurea through the ionic active groups are dealt with. A discussion follows of the synthesis of high polymers and permutoids with active groups of the chlorophyll and hemin series obtained by the introduction of the corresponding active groups into high‐polymeric compounds, by copolymerization, and by inclusion of the prosthetic group in the polycondensation process. A report is added on the optical properties of the high‐molecular compounds provided with active groups and on remarkable differences between low‐molecular compounds in a dissolved state and as active groups linked to high polymers. The apparatuses developed for taking absorption and reflection spectra are described. Finally, the catalytic effect of the high polymers provided with active groups of the hemin series is examined.
Copolymères greffés
Authors: Smets G. , Claesen M.
Published: April 2003

Des copolymères greffés ont été préparés par réaction de transfert de chaǐne entre un radical monomérique et une molécule de polymère suivie de l'addition de monomère au macroradical. Dans ce but, les monomères vinyliques ont été polymérisés en présence de quantités appréciables (25% et plus) de polymère étranger, en présence de peroxyde de benzoyle comme initiateur (0.5% par rapport au monomère). La séparation des copolymères greffés des autres homopolymères présents dans le mélange est basée sur les différences de solubilité de ces produits. Les expériences ont été menées au départ d'acétate de vinyle en présence de polyméthacrylate de méthyle à différentes températures, savoir 75°, 85° et 95°C.; le taux de greffage dépend fortement de la t°, et atteint respectivement 15, 32 et 53% d'acétate de vinyle (analyses chimiques et infra‐rouges) Ces copolymères greffés ont été identifiés par leurs propriétés de solubilité et leur comportémént osmotique et viscosimétrique; les valeurs de k′ (constante de Huggins) et μ varient considérablement si on compare un mélange de polymères, un copolymère habituel et un copolymère greffé, dont les poids moléculaires et le taux d'acétate de vinyle sont semblables. De la měme façon, il a été possible d'obtenir un copolymère greffé par polymérisation du chlorure de vinyle en présence de polyméthacrylate de méthyle. Les réactions inverses toutefois, savoir la polymérisation du méthacrylate de méthyle en greffage sur les acétate ou chlorure de polyvinyle, n'ont pu ětre mises en évidence par des opérations de fractionnement. Des expériences semblables ont été effectuées à différentes températures avec le styrène en présence de polyméthacrylate de méthyle, et inversément le méthacrylate de méthyle en présence de polystyrène. Dans les deux cas les réactions réussissent et se manifestent par une solubilisation de la fraction polystyrénique. Dans le premier cas, la quantité de polystyrène solubilisé croǐt avec une augmentation de température. Ces copolymérisations par greffage sont reliées aux phénomènes de dégradation, décrites ailleurs, et à la stabilité des radicaux formés au cours des réactions.
Polyalkylene sulfides. X. The reaction of hexamethylenedithiol with 1,3‐butadiene1
Authors: Marvel C. S. , Cripps Harry N.
Published: April 2003

Hexamethylenedithiol and 1,3‐butadiene react in an emulsion system in the presence of peroxides to produce 1,6‐dicrotylmercaptohexane. Hexamethylenedithiol and 1,6‐dicrotylmercaptohexane did not yield a polymer by either bulk or emulsion techniques which confirms earlier work that a sulfur atom beta to a double bond prevents free radical initiated addition of a mercaptan to that bond. Hexamethylenedithiol does give a polymer with bicrotyl showing that a buried double bond will react. Polymerizations of hexamethylenedithiol with both biallyl ether and bis‐10‐hendecen‐1‐yl ether will take place, but they show that an oxygen atom beta to a double bond inhibits the free radical catalyzed addition of a mercaptan to that bond.
Copolymerization theory of the vulcanization of rubber. VI. Hydrogen sulfide effects and some self‐limiting features
Authors: Craig David , Juve A. E. , Davidson W. L. , Semon W. L. , Hay D. C.
Published: April 2003

Vulcanization with sulfur is ascribed to the formation of sulfur radicals which are believed to copolymerize with the rubber molecule double bonds. Hydrogen sulfide is proposed as necessary for chain initiation but when formed in sufficient amounts serves as a chain terminator. This is believed to lead to numerous self‐limiting features including ceiling temperatures, post‐vulcanization and delayed action effects. Initiation may result from the oxidation of H2S to sulfur radicals and termination to the formation of HS radicals.
Dynamic studies on polymeric liquids
Authors: Harper R. C. , Markovitz H. , Dewitt T. W.
Published: April 2003

The dynamic properties of low molecular weight polyisobutylene and silicone oils have been investigated over a range of frequencies and temperatures. When subjected to oscillating stresses, these materials behave as though they had a shear modulus as well as a viscosity. Dynamic viscosities and rigidities have been determined at frequencies between 10 and 100 cycles per second and at temperatures between −50° and +60°C. Falling ball viscosities were also obtained over the same temperature range. In general, moduli increase with increasing frequency and decreasing temperature while dynamic viscosities decrease with increasing frequency and increasing temperature. At room temperature and above, the dynamic viscosity varies very little with the frequency and is essentially the same as the falling ball viscosity. At lower temperatures the dynamic viscosity decreases considerably with increasing frequency but extrapolates to the falling ball viscosity at zero frequency. If these materials are regarded as complex Maxwell liquids, the dynamic rigidities and viscosities may be written as functions of a “reduced frequency” equal to the frequency multiplied by an exponential of a constant divided by the absolute temperature. This constant can be evaluated from the slope of the linear plot of the logarithm of the falling ball viscosity over the absolute temperature versus the reciprocal of the absolute temperature. For a given material a single constant suffices to bring the data at all frequencies and temperatures into a single plot similar to that used by Ferry.
Effect of solvation on sedimentation experiments
Authors: Wales M. , Williams J. W.
Published: April 2003

The sedimentation equilibrium of polymers in mixed solvents at infinite dilution of polymer was analyzed by thermodynamic methods equivalent to those used by Stockmayer and Kirkwood and Goldberg for the light scattering case. It was found that the apparent weight‐average molecular weight in a binary solvent mixture (when nonrefractometric methods are used to measure the experimental concentration gradient) is formally identical with that derived by Lansing and Kraemer on the assumption of stoichiometric combination of one of the solvents with the polymer. The “solvation number” now actually measures a preference for one solvent and can be expressed in terms of thermodynamic quantities characteristic of the ternary polymer‐solvent system. In the case of refractometric measurements, where the two solvents have different refractive indices, refraction terms similar to those encountered in light scattering theory for mixed solvents also enter. Under equilibrium conditions, for polymer solutions in pure solvents, thermodynamics can say nothing about “solvation,” which is inseparable from the over‐all nonideal behavior at finite concentrations. There is strong reason to believe that all types of experiments designed to measure solvation in mixed solvents under equilibrium conditions must give the same answer, since the same thermodynamic quantities determine polymer‐solvent interactions in all cases. By assuming a dynamic equilibrium between sedimentation and diffusion in the equilibrium case and using the sedimentation term for the sedimentation velocity case, an expression for the sedimentation constant in mixed solvents at infinite dilution of polymer has been obtained. This expression is almost the same as that previously derived by Schachman and Lauffer, the difference occurring in an assumption about the density of solvated liquid made by these authors.
Study of the mechanism of ionic polymerization using radioactive tracers
Authors: Colclough R. O.
Published: April 2003

A thorough experimental study of the ionic polymerization of styrene using antimony pentachloride containing radioactive antimony as the catalyst shows that, contrary to earlier work, no catalyst remains attached to the polymer chain. The implication of this finding for the mechanism of ionic polymerization is discussed.
Rates of initiation in vinyl polymerization
Authors: Baysal Bahattin , Tobolsky Arthur V.
Published: April 2003

The rates of initiation Ri of polymer chains in styrene and methyl methacrylate have been measured for four different catalysts. The results for styrene at 60°C are: Ri = 1.28 × 10−5[azo]; Ri = 2.96 × 10−6[Bz2O2]; Ri = 6.12 × 10−7[CHP]; Ri = 9.96 × 10−5[BHP]. Azo, Bz2O2, CHP, and BHP refer to 2‐azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, and tert‐butyl hydroperoxide, respectively. Rates are expressed in moles per liter per second. The corresponding results for methyl methacrylate at 60° are: Ri = 1.42 × 10−5[azo]; Ri = 6.62 × 10−6[Bz2O2]; Ri = 3.92 × 10−7[CHP]; Ri = 7.30 × 10−8[BHP]. Catalyst efficiencies for azo and Bz2O2 are shown to be nearly unity in both monomers. Chain transfer constants were calculated for all catalysts in both monomers. Photopolymerization was shown to proceed via chains growing in one direction only. The polymerizations were all carried out in the pure monomers (bulk polymerization) with exclusion of oxygen and other inhibitors.
Copolymerization characteristics of fumaronitrile
Authors: Price Charles C. , Gilbert Richard D.
Published: April 2003

Copolymerization of fumaronitrile (M2) with styrene (M1) gave the following values for characteristic copolymerization constants: r1 = 0.23 ± 0.1; r2 = 0.01 ± 0.01; Q2 = 0.6; e2 = 1.6. With methyl methacrylate (M1) the values were r1 = 3.5 ± 0.5; r2 = 0.01 ± 0.01; Q2 = 0.4; e2 = 2.0.
Structure of neoprene. V. Viscosity‐conversion relationships in sulfur‐modified polychloroprenes
Authors: Mochel W. E.
Published: April 2003

The solution properties, i.e., gel content and intrinsic viscosity, of sulfur‐modified polychloroprenes were examined at monomer conversions ranging from 5 to 95% to obtain information about the mechanism of action of the sulfur modifier and other factors influencing the polymerization. Sulfur‐modified polymers isolated at conversions beyond 10–40%, depending upon the polymerization temperature, were found to be insoluble before treatment with tetraethylthiuram disulfide. These results, in confirmation of earlier results with radiosulfur, indicate that sulfur in chloroprene polymerization does not act as a chain transfer agent. The intrinsic viscosity‐conversion relationships for sulfur‐modified, tetraethylthiuram disulfide‐treated polychloroprenes show two viscosity maxima. The first maximum, at 15–20% conversion, appears to be the result of a change in polymer structure and, therefore, a change in the molecular weight‐intrinsic viscosity relationship. The second maximum appears at high conversion, 85–90%, and is caused by the formation of relatively tight gel that cannot be solubilized by the tetraethylthiuram disulfide scission reaction. The less pronounced decrease in viscosity beyond this peak is caused by removal of high molecular weight polymer by gelation, leaving relatively lower molecular weight sol polymer.
Effect of chemical structure on physical properties of isomeric polyesters
Authors: Izard E. F.
Published: April 2003

It has been shown that changes in chemical structure of aromatic polyesters have a pronounced effect on the melting points and crystallinity of the polymers. Changes which remove the carboxyl group from the ring result in marked lowering of the melting point and toughness of the polymers. Changes which separate aromatic nuclei lower melting point but not as markedly as the above change. Changes which put an odd number of atoms in the polymer chain markedly lower the melting point. Changes which interfere with the possibility of co‐planarity of the components very markedly affect the crystallinity, and to a lesser extent the sticking point of polymers.
Polyalkylene sulfides containing silicon. XI
Authors: Marvel C. S. , Cripps Harry N.
Published: April 2003

The optimum pH for the emulsion polymerization of hexamethylenedithiol and diallyldimethylsilane was found to be in the region of 3.0 to 4.0. A variety of polyalkylene sulfides containing silicon were prepared using bulk, solution, and emulsion polymerization techniques. All of the polyalkylene sulfides which contained silicon were heavy oily materials which were very “tacky”.
Molecular distribution in condensation polymers
Authors: Stockmayer Walter H.
Published: April 2003

The theory of molecular distribution in condensation polymers has been extended to include systems of a rather general type. Equations for the distribution and the weight‐average molecular weight are given.
X‐ray diffraction studies of addition compounds of amylose with inorganic salts
Authors: Senti Frederic R. , Witnauer Lee P.
Published: April 2003

Many salts in aqueous alcohol solution can be exchanged for the alkali in oriented filaments of alkali amylose. If the filaments are held taut during exchange, orientation is retained, and excellent fiber patterns are produced. By this method, compounds of amylose were obtained with the iodide, bromide, formate, acetate, and propionate of potassium and with sodium bromide and ammonium fluoride. In addition, potassium bicarbonate–amylose was formed by the action of carbon dioxide on moist filaments of potassium hydroxide–amylose. Data on the composition of the amylose–potassium salt filaments indicate stoichiometric compound formation between amylose and salt, the ratio of salt molecules to glucose residues being 1:2 for the iodide, bromide, formate, and tetragonal form of the acetate, and 1:1 for the propionate and the orthorhombic form of the acetate. As shown by x‐ray diffraction patterns, the potassium salts crystallized in two structures. One, based on a tetragonal unit cell, was common to the iodide, bromide, formate, acetate, and bicarbonate; the other, based on an orthorhombic unit, was the stable structure for the acetate and the propionate. Dimensions of the tetragonal unit cells of air‐dried filaments of the iodide and bromide were identical, with a0 = 10.7 and c0 (fiber axis) = 16.1 A. Corresponding dimensions for the formate and acetate were 10.8 and 16.1 A., and those for the bicarbonate were 10.8 and 15.8 A. The orthorhombic structures of the potassium acetate and propionate addition compounds with amylose appeared to be isomorphous, unit cells having a0 = 11.0, b0 = 18.1, c0 (fiber axis) = 17.9 A. for the acetate, and a0 = 11.4, b0 = 18.0, c0 = 17.6 A. for the propionate. The tetragonal structural modification is of particular interest. Observed diffraction maxima were consistent with the enantiomorphous space groups, P4121 and P4321, and this, together with composition and density data, demands that the amylose chains posses fourfold screw symmetry, with four glucose residues corresponding to the fiber repeat period of 16.1 A. Succesive residues in the amylose chain must, therefore, be identical. This is the first x‐ray evidence which has demonstrated the identity of successive residues in the amylose chain.

From a Patterson projection of potassium bromide amylose, the positions of the inorganic ions were determined. The Fourier projection, ρz(x,y), computed from Fhk0 with signs determined by the bromide ion, confirmed the location of the inorganic ions and gave a general outline of the packing of the amylose chains.
Polysoaps. III. Influence of solubilized benzene on reduced viscosity of an n‐dodecyl bromide addition compound of poly‐2‐vinylpyridine
Authors: Layton Lionel H. , Jackson Earl G. , Strauss Ulrich P.
Published: April 2003

The effect of solubilized benzene on the viscosity of aqueous solutions of a polysoap, derived from poly‐2‐vinylpyridine and n‐dodecyl bromide was found to be different, both in kind and in order of magnitude, from the simple viscosity depression characteristic of solubilized aliphatic hydrocarbons. As the benzene content of a given solution is increased, the viscosity at first rises, reaches a maximum, and decreases again, below its initial value, until the solution is saturated. The maximum rise in the reduced viscosity increases very strongly with increasing concentration of the polysoap, indicating that the viscosity increase is caused by interactions between polysoap molecules. On the other hand, the reduced viscosity depression at benzene saturation is not sensitive to the polysoap concentration and may therefore be ascribed to a contraction of the individual polysoap molecules. Both at the viscosity maximum and at benzene saturation, the respective amounts of benzene solubilized by unit amount of polysoap were found to be independent of the polysoap concentration. These results are interpreted to mean that the polysoap molecules act as independent solubilizing units, but that their structure is changed by the solubilized benzene is such a way as to strongly affect their mutual interaction. Based on the assumption that the benzene is solubilized both in the hydrocarbon and in the ionic regions of the polysoap molecules, a mechanism for the structure changes which would explain the viscosity maxima is suggested.
Molecular weight dependence of intrinsic viscosity of polymer solutions
Authors: Krigbaum W. R. , Mandelkern L. , Flory P. J.
Published: April 2003

Intrinsic viscosities of low molecular weight polystyrene fractions measured in an “ideal” solvent (i.e., in cyclohexane at the “θ temperature,” 34°C.) are in accord with the relationship [η]θ = KM1/2. Even at a molecular weight of only 4000, the observed value of K agrees with that for high molecular weights.
Activity coefficient of byions and ionic strength of polyelectrolyte solutions
Authors: Kagawa Ikumi , Katsuura Kakuji
Published: April 2003

With the polyelectrolyte solutions prepared by adding potassium chloride into the solution of sodium carboxymethyl celluloses in the various proportions, the activity of chloride ion was measured potentiometrically, from which the ionic strength of the sample solutions was computed. From these experimental results it has been found that Lewis' law of ionic strength, although it does not hold in the original sense as it is, seems applicable for the polyelectrolyte solutions if an assumption is permitted that the so‐called segment accompanied by a portion of counterions behaves like a permanent point‐charge ion. Thus, the degree of fixation of counterions was computed, and the dissociation state of strong polyelectrolyte was discussed. Furthermore, a brief report was made on the difference between the activity coefficients of byions and counterions in their thermodynamical meaning as well as on the connection of the nature of polyelectrolyte solutions with that of simple electrolyte solutions according to the authors' two phase conception.
Fluorine‐containing polymers. I. Copolymers of perfluoro‐olefins
Authors: Adams R. M. , Bovey F. A.
Published: April 2003

We have studied the copolymerization behavior of perfluoropropene, perfluorobutene‐1, perfluorobutene‐2, perfluoroisobutene, perfluoropentene‐1, and perfluorononene‐1. We have so far not succeeded in homopolymerizing these olefins. However, certain nonfluorinated, nonconjugated comonomers–ethylene, vinyl. chloride, vinyl acetate, and the vinyl alkyl ethers–were found to copolymerize readily, giving copolymers containing up to 50 mole per cent, and in some cases slightly more than this, of the perfluoro‐olefin in the copolymer. The higher members of the series copolymerize in general less readily than the lower members. The products ranged from viscous oils to tough, film‐forming solids. The difficulty of homopolymerization and the relative ease of copolymerization of the perfluoro‐olefins with the above comonomers are discussed and interpreted in terms of probable electron distributions around the double‐bond.
Polymerizable derivatives of long‐chain fatty acids. VII. Copolymerization of vinyl acetate with some long‐chain vinyl esters
Authors: Port William S. , Jordan E. F. , Hansen John E. , Swern Daniel
Published: April 2003

A study was made of the copolymerization of vinyl acetate with vinyl palmitate, vinyl stearate, and vinyl oleate, respectively, True copolymerization was shown to have occurred on the basis of the solubility characteristics of the crude copolymers over a wide range of compositions. The monomer reactivity ratios for the comonomers vinyl palmitate (r1) and vinyl acetate (r2) were determined by two methods. One, based on an analysis of the copolymer, gave r1 = 0.78 ± 0.10 and r2 = 1.15 ± 0.13; the other, based on an analysis for each monomer in the mixture remaining after polymerization, gave r1 = 0.66 ± 0.07 and r2 = 0.84 ± 0.10. When the vinyl palmitate or vinyl stearate content of the copolymer exceeded about 20–25 mole per cent, the copolymers exhibited first‐order transition points which were determined using a refractive index technique as well as a polarizing microscope method. Where no transition point could be observed, brittle point measurements were made.
Determination of absolute turbidities
Authors: Oster Gerald
Published: April 2003

A simple method is described for determining absolute turbidities of solutions based on the transmission of light of a highly turbid solution possessing no dissymmetry or depolarization. Stable suspensions of particles of vitreous silica (Ludox) used for this purpose possessed a weight average molecular weight of för millions.
Determination of the molecular weights of fractionated polyvinyl acetates by a new type of light‐scattering instrument
Authors: Bosworth P. , Masson C. R. , Melville H. W. , Peaker F. W.
Published: April 2003

A new light‐scattering instrument is described, in which the incident light beam is rotated by a mirror system, and the photomultiplier cell (E.M.I. type 5311) which measures the scattered light remains stationary. A study of the osmotic and light‐scattering molecular weights (Mw) of a series of polyvinyl acetate fractions shows that the process of fractionation separates the several molecular species present according to both size and shape. The average dimensions of the polymer chain (D) can be deduced from the dissymmetry measurements, assuming the random chain model. These results show that the most insoluble fraction has the highest molecular weight, but is also the least extended in solution. The lower‐molecular‐weight samples are relatively longer. The ratio Mw/D2 is a measure of the degree of branching of the polymer chain, and the minimum value measured for ten samples is 0.5. This is believed to be the value characteristic of the linear molecule. A photopolymer prepared at −25°C. and low conversion, that is, under conditions favoring the formation of linear polyvinyl acetate molecules, also had this same minimum value of Mw/D2 = 0.5.
Étude expèrimentale de la lumière diffusée par des bâtonnets anisotropes
Authors: Horn P. , Benoit H.
Published: April 2003

Nous avons appliaué à l'étude de suspensions de virus de la mosaïque du tabac les résultats de la théorie de la diffusion par des bâtonnets anisotropes. Dans ce but on détermine d'abord l'anisotropie δ du bâtonnet en extrapolant à angle de diffusion nul le facteur de dépolarisation ρv. On trouve ainsi δ = 0,3, valeur un peu forte comparée à celle déduite des expériences de biréfringence d'écoulement (δ = +0,1). Enfin comparant les répartitions angulaires des différentes composantes avec la courbe théorique, on obtient un accord trés satisfaisant en prenant pour longueur des bâtonnets L = 2300 Å, ce qui constitue un bonne vérification de la théorie précitée.

La même analyse appliquée à l'acide thymonucleique S VIII préparé par Schwander en solution NaCl 1M neutre conduit aux valeurs:
Copolymerization of vinylsulfonic acid derivatives with butadiene
Authors: Marvel C. S. , Menikheim V. C. , Inskip H. K. , Taft W. K. , Labbe B. G.
Published: April 2003

Copolymers of vinylsulfonic acid derivatives with butadiene, isoprene, and styrene have been prepared. The evaluation of butadiene‐vinylsulfonic acid ester copolymers indicates that these rubbers have good low‐temperature characteristics and that the stress‐strain properties of the n‐butyl vinylsulfonate copolymer approach those of the standard GR‐S rubber; however the oil resistance properties are poor. The stress‐strain properties of the butadiene‐n‐hexyl vinylsulfonate copolymer are inferior to those of the n‐butyl analog.
Role of depropagation reactions in the copolymerization of styrene and sulfur dioxide
Authors: Barb W. G.
Published: April 2003

The rate of reaction of sulfur dioxide in styrene solutions at 60°C., with azodiisobutyronitrile as thermal catalyst, has been measured: (1) by gravimetric determination of the total rate of polymerization and analysis of the polymer formed and (2) volumetrically. An experimental arrangement for the latter method, which can be used when the partial pressure of the solvent (styrene solution) is appreciable compared to that of the solute (sulfur dioxide) is described. The kinetics of reaction conform to the mechanism previously proposed, according to which sulfur dioxide reacts in the form of a 1/1 styrene/sulfur dioxide complex C. It is shown that certain features attributable to depropagation reactions, such as the increase in the styrene content of the copolymer with decreasing styrene concentration in the reaction mixture, are much more marked at 60°C than at 20°C. By combining the rate measurements with new data on the temperature dependence of copolymer composition at elevated temperatures, it is possible to assign an approximate value to the velocity constant of a depropagation reaction involving breakage of a carbon‐sulfur bond. The activation energy is estimated at 50 to 62 kJ. (12 to 15 kcals.), which is much lower than that for depropagation of a vinyl polymer; the frequency factor is about 4 X 1010 to 3 X 1012sec.−1. Some data on the composition of polymers prepared at 0° and −20°C. are appended. It is shown that the C· + C propagation step, which seems negligible at 20°C. or above, becomes of some significance at lower temperatures. Under these conditions polymers containing less than two styrene units per sulfur dioxide can be prepared.
Spaltung des fibrinmoleküls mittels cupriäthylendiamin
Authors: Schauenstein E. , Hochenegger M.
Published: April 2003

Die Untersuchungen ergaben, dass beim Fibrin‐Molekül von einer kontinuierlichen Verteilung der aromatischen Aminosäuren im allgemeinen nicht gesprochen werden kann. Die Einwirkung von Cupriäthylendiamin auf Fibrin führt zu einem Zerfall des Teilchens in zwei Fraktionen “I” und “II”. Fraktion I macht etwa 75% des Moleküls aus, ist stabil, unlöslich in NaCl‐Lösung, enthält das gesamte Tyrosin des Fibrinmoleküls sowie 3% Tryptophan. Obwohl diese Fraktion noch deutlich die Eigenschaften eines hochpolymeren Eiweisskörpers zeigt, kann sie durch Thrombin nicht mehr fibrillär polymerisieren. Fraktion II dagegen macht rund 15% des Fibrins aus, ist labil, löslich in NaCl‐Lösung, enthält kein Tyrosin, jedoch ebenfalls 3% Tryptophan, wahrscheinlich viel mehr Arginin als Fraktion I und trägt den Charakter eines Proteids.