bluuebunny/crossref_metadata_2025 huggingface dataset:
Redox recipes. VI. Redox systems containing potassium chromate as oxidizing constituent
Authors: Kolthoff I. M. , Meehan E. J.
Published: April 2003

The emulsion copolymerization of butadiene (75)‐styrene (25) is initiated by redox systems containing potassium chromate as oxidizing constituent. In alkaline (soap) recipes, the system chromate‐arsenic trioxide is especially effective, giving a rate of conversion of about 20% per hour at 30°C. with 5 parts of potassium myristate (0.3 part of potassium chromate and 0.07 part of arsenic trioxide per 100 parts of monomers). Other fatty acid soaps or sodium alkyl sulfate may be used instead of myristate, although no other soap or emulsifier tested gives a rate as large as does myristate. Mercaptan has a slight accelerating effect but the presence of mercaptan is not necessary for initiation of polymerization. The use of arsenic trisulfide as reducing agent gives rise to rapid polymerization but the rates vary with different suspensions of arsenic trisulfide. Potassium antimonyl tartrate also may be used in combination with chromate to give rapid polymerization at 40°C. with fatty acid soap. Tin(II) is much less effective than either arsenic(III) or antimony(III). Inorganic reducing agents which in combination with chromate are inefficient in initiating the copolymerization include iron(II), thallium(I), dithionite, hydrazine, hydroxylamine, and sulfide.
Redox recipes. VIII. A recipe with ferric versenate, sodium sulfide and hydroperoxide as activating system (veroxasulfide recipe)
Authors: Kolthoff I. M. , Meehan E. J.
Published: April 2003

A new recipe called the Veroxasulfide Recipe is described for the polymerization of butadiene (75)‐styrene (25). The initiating system is composed of ferric versenate, sodium sulfide, and a hydroperoxide. With K‐fatty acid soap as emulsifier, the use of 0.00728 part of ferric nitrate nonahydrate (corresponding to 10−4 M ferric iron in the aqueous phase), 10−4 M versene, 0.02 part of sodium sulfide, and 0.1 part of Diox D, the following conversions are found at 5°C.:

Time, hrs.
1
2
4
8
12

Conversion, %
8
16
32
66
85

The optimum amount of sodium sulfide is 0.02 part (equivalent to 0.062 part of the nonahydrate) but the rate does not depend critically on the amount. The optimum rate is found with approximately 0.00025 M ferric versenate (8.3% in 8 hours at 5°C.) and the rate may be adjusted conveniently by adjustment of the amount of ferric versenate. The presence of a considerable excess of versene over ferric iron does not affect the rate. With less versene than the amount equimolar to the amount of ferric iron the rate corresponds approximately to that observed with the corresponding amount of ferric versenate; that is, the rate is determined by the amount of ferric versenate rather than by the total amount of ferric iron. Latex of normal fluidity is obtained with charges containing 0.5 part or more of potassium chloride; without added electrolyte thick latex subject to precoagulation is obtained. Satisfactory rates are found with mixtures of Dresinate 214 and K‐fatty acid soap. Mercaptan is not needed for initiation; the same rate is found with n‐dodecyl mercaptan, with sulfole mercaptan, and without mercaptan. The kind of agitation has no or slight effect on the rate. Added oxygen has only a slight effect which is largely eliminated by the addition of sodium dithionite. A recipe is given which at −5°C. yields 70–75% conversion in 12 hours. Polymerization using the Veroxasulfide recipe at 25°C. may provide a sensitive test for traces of iron in ingredients used in polymerization recipes, since with 2 × 10−6 M ferric versenate (corresponding to 0.1 p.p.m. of ferric iron per liter of aqueous phase), 32% conversion is reached in 11 hours, whereas in the absence of iron 3% conversion is reached in the same time.
Étude optique de la morphologie des particules de thymonucléate de sodium en fonction du pH et en solution diluée
Authors: Horn P. , Leray J. , Pouyet J. , Sadron Ch.
Published: April 2003

Certaines propriétés physiques des solutions de thymonucléte sodique ont été déterminées en solution neutre et après ajustement au pH 3.8 au moyen d'acide chlorhydrique 0.01 M. On a trouvé que la viscosité intrinsèque au gradient zéro est 5700 en solution neutre et 3900 au pH 3.8. De plus, cette dernière viscosité reste inchangée après reneutralisation de la solution avec de la soude 0.01 M. La diffusion de la lumière montre que le poids moléculaire est le même dans les deux cas, et indique que les particules sont plus dissymétriques en solution neutre. Des mesures de biréfringences d'‐ écoulement et d'angles d'extinction permettent de confirmer cette interprétation.
Modèle statistique des grosses molécules à chaînes courtes. V. Diffusion de la lumière
Authors: Peterlin Anton
Published: April 2003

Les fonctions de diffusion P(ϑ) des molécules linéaires, présentant un degré de rigidité variable et caractérisées par une logueur permanente a (comme définies par Kratky et Porod) ont été calculées; a est défini comme étant la projection d'une chaîne infiniment longue dans la direction du premier segment moléculaire. Les résultats sont obtenus sous la forme de développements en série valables pour des degrés de flexibilité moyens à élevés. On montre que les fonctions de diffusion ainsi obtenues sont comprises entre celles correspondant à un bâtonnet rigide et à une pelote statistique. En outre, les auteurs indiquent une méthode qui permet d'obtenir les paramêtres moléculaires a, la longueur L et le diamètre de la spire R aux dépens des résultats expérimentaux.
Diffusion of organic molecules through wood
Authors: Narayanamurti D. , Kumar Vidya Bhushan
Published: April 2003

The diffusion of alcohols, glycerol, phenol, formic, acetic and butyric acids through four species of Indian timbers in the water‐saturated condition has been studied and the results reported. In contrast to several inorganic ions, Fick's law is obeyed by the organic molecules in the concentrations studied. As is to be expected, the diffusion in the axial direction is several times that in the other directions. The speed of diffusion decreases rapidly with the molecular weight of the substance and the density of the wood. While in the case of the alcohols the logarithm of the diffusion constant varies as the molecular weight with the acids the diffusion constant is proportional to the molecular weight.
A new phenomenon in flow birefringence of solutions of macromolecular substances
Authors: Arlman E. J. , Boog W. , Coumou D. J.
Published: April 2003

Measurements on flow birefringence of solutions of polyvinyl chloride in cyclohexanone revealed that the angle of orientation increases with decreasing concentration of the solution. That this surprising effect was not due to constructional or experimental errors was demonstrated by results obtained with polystyrene, which were in agreement with literature data.
Infrared spectrophotometric studies on polyethylene. I. Structure
Authors: Rugg Frank M. , Smith Joseph J. , Wartman Lloyd H.
Published: April 2003

A series of polyethylene resins made by making progressive changes in temperature, pressure, and catalyst content has been studied by infrared absorption spectroscopy. From the methyl content and the number‐averages molecular weight of each resin, it was found that as molecular weight increases degree of branching decreases. Also revealed was the fact that each of the three types of double bond groups present, i. e., RHCCH2, RHCCHR, and RRCCH2, decreases in concentration with increasing molecular weight. Using polarized radiation, high resolution grating spectra were obtained on polyethylene films which had been highly oriented by cold drawing 500%. The results show that the CH3 terminated branches are not predominantly oriented either parallel or perpendicular to the direction of stretch. It is the authors' view that the chain branches vary in length with a considerable fraction short enough to be essentially at right angles to the long chain axis while others are sufficiently long to be parallel to the long chain axis in stretched polyethylene. When a stretched polyethylene film is heat relaxed (110–115°C.), its spectra using polarized radiation reveal the presence of crystallites in which the long carbon‐to‐carbon chain axes are predominantly oriented at right angles to the direction of stretch.
Refractometric determination of second order transition temperatures in polymers. VI. Effect of molecular weight on the transition temperature of polyvinyl acetate
Authors: Wiley Richard. H. , Brauer G. M.
Published: April 2003

The transition temperatures (TG) of unfractionated vinyl acetate polymers increase from 17° to 26° as the molecular weight increases from 14,000 to 104,000 and from 26° to 28° as the molecular weight increases from 104,000 to 1,120,000. The minimum molecular weight above which increase in molecular weight does not appreciably change TG is about 100,000. TG increases linearly with the reciprocal of the square root of the molecular weight.
Application of the steady state method to benzoyl peroxide initiated polymerization of styrene
Authors: Horikx M. M. , Hermans J. J.
Published: April 2003

The steady state method is applied to the benzoyl peroxide initiated polymerization of styrene in toluene at 80°C. The reaction mixture is kept homogeneous by stirring. A theoretical discussion shows that the time needed to reach the steady state concentrations with an accuracy of 1% or better is about seven times the average time which the mixture spends in the reaction vessel; this is confirmed by experiment. The experimental results show that the rate of polymerization can be represented by the formula:

where m is the monomer concentration, while k and β are constants. It is found that β = 1.19 liter/mole. The apparent order of the reaction, with respect to monomer, increases from 1.18 when m = 1.8 mole/liter to 1.36 when m = 0.4 mole/liter. An analysis of the limits of experimental error indicates that in the conventional method this change in apparent reaction order would have been of the same order of magnitude as the experimental error. The accuracy of the steady state method, however, is sufficient to establish this change unambiguously. Numerous data from the literature concerning the polymerization of styrene and other monomers are discussed, and are found to be in good agreement with the conclusions reached in the present work. Explanations are offered for a number of discrepancies found in the literature.
A theoretical analysis of the distribution of tensile strength of vulcanized rubber
Authors: Kase Shigeo
Published: April 2003

By means of a mathematical treatment the distributions of the tensile strength of natural rubber and GR‐S were studied. As a result of this study it is shown that the distributions are of the so‐called doubly exponential type.
Copolymerization characteristics of some vinylnaphthalenes and vinylphenanthrenes
Authors: Price Charles C. , Halpern Benjamin D. , Voong Sing‐Tuh
Published: April 2003

β‐Vinylnaphthalene, 6‐chloro‐2‐vinylnaphthalene, 4‐chloro‐1‐vinylphenanthrene, and 2‐ and 3‐vinylphenanthrenes have been copolymerized with styrene, methyl methacrylate and methyl acrylate. All copolymerize well to give products generally softening at higher temperatures than polystyrene of its copolymers. Analysis of the relative reactivities in copolymerization indicates that, with the exception of the single α‐vinylnaphthalene derivative, these monomers are more reactive in copolymerization than styrene. This is in agreement with expectations based on the greater possibilities for resonance stabilization of an adjacent free radical by the naphthalene and phenanthrene nuclei.
Studies on aldehyde‐protein interactions. I. Reaction of amino acids with lower aldehydes
Authors: Robert L. , Penaranda F. S.
Published: April 2003

The kinetics of reaction between amino acids and lower aldehydes (acetaldehyde, propylaldehyde) was followed by the Van Slyke technique and a quantitative chromatographic method. In a narrow range of pH (pH 6–7), the reaction was found to be bimolecular. Graphically computed bimolecular kinetic constants are presented for a certain number of amino acids reacting with acetaldehyde. Under certain conditions (for instance, tryptophane in acetic acid solution with acetaldehyde) the reaction rate was slowed down to trimolecular. At some acid or alkaline pH values the exact order of the reaction could not be determined (it was not of the first, second, or third order). Except for tryptophane, which reacted more rapidly in acid media, the amine‐aldehyde combination rate was accelerated by rising pH. The combination rate of histidine is directly proportional to the acetaldehyde concentration, the proportionality factor being unchanged with increasing the pH from 3.00 to 6.20. In some cases (for example, propylaldehyde with lysine) the amino nitrogen content reached a minimum after 10–20 minutes, and then rose to attain even the initial value. Specific viscosity did not change (tryptophane), or else decreased (lysine, arginine, histidine) during the acetaldehyde‐amino acid reaction. In acetaldehyde‐NaOH or acetaldehyde‐morpholine mixtures the viscosity was unaltered even when the solution became rapidly turbid and aldehyde‐resin precipitated. It was possible to separate the reaction products obtained during the formation of aldehyde‐resin and aldehyde‐amino acid interaction by the method of paper electrophoresis. The fluorescent patterns were characteristic for each amino acid. Most of the amino acids showed 3–6 spots of different fluorescent color. This rendered probable the hypothesis that the same aldehyde condensation products are formed in amino acidaldehyde mixtures as in alkali‐acetaldehyde solution.
Sedimentation analysis and some related problems
Authors: Williams J. W.
Published: April 2003

With the development of the ultracentrifuge by Svedberg there was provided a group of methods for the determination of solute molecular weight and of distribution of molecular weights in proper solutions. In addition to the sedimentation equilibrium and the sedimentation velocity experiments, there are other closely related molecular kinetic phenomena which, when taken together, form a collection of very useful tools in an area of macromolecular chemistry.

The principal past use of the ultracentrifuge has been in the determination of the molecular weight and the homogeneity of proteins. In this report the attempt has been made to point the way for concerted action in the return to the original problem–that of investigating the dispersity of macromolecular and other colloidal solutions. Among other things, there is proposed in outline a combination of the sedimentation velocity and sedimentation equilibrium experiments to provide mass distribution data in macromolecular systems. While the main emphasis is devoted to the theory of the sedimentation methods and their unique usefulness to this end, there have been presented shorter discussions of diffusion and osmotic pressure as such and in their relationships to the sedimentation problems.

Recognition is also made of the fact that the optical systems for the study of the redistribution of the components in the diffusion and sedimentation cells are now in a state of change, with a rapid adaptation of several interference methods to take the place of the more classical refractometric schemes. The change is being made in the interest of a greatly enhanced accuracy, even to the point that diffusion behavior in systems which contain two solutes can properly be observed.
Synthetische Kohlenhydrat‐Eiweissverbindungen
Authors: Micheel Fritz
Published: April 2003

Die besten Methoden zur Synthese von Kohlenhydrat‐Eiweissverbindungen, in denen beide Komponenten in biologisch möglicher Art kovalent miteinander verbunden sind: (1) Mono‐saccharid‐ oder Poly‐saccharid‐carbonsäuren werden über ihre Azide peptidartig an die ε‐Aminogruppen der Lysinreste in Proteinen gebunden. (2) 1‐Cyanamidoverbindungen von Monosacchariden kondensieren sich mit den freien Aminogruppen (siehe 1) der Proteine zu Zucker‐guanyl‐proteinen. (3) 1‐Alkyl‐iso‐thioharnstoffderivate von Mono‐sacchariden geben (wie bei 2) mit Proteinen Zucker‐guanyl‐proteine. Es reagieren nach Verfahren (2) und (3) weniger als 50% der ε‐Aminogruppen der Lysinreste in den Proteinen. Dies dürfte auf eine Blockierung der Aminogruppen durch Carboxyl‐ u.a. Gruppen zurückzuführen sein. Durch Umsetzung von Poly‐saccharidproteinverbindungen (nach Methode 1 erhalten) mit Ölsäurechlorid werden Kohlenhydrat‐oleyl‐proteine synthetisiert, in denen die Oleyl‐reste an die Protein‐reste, nicht an die Kohlenhydratreste, gebunden sind. Sie enthalten die Bausteine von Lipoiden in kovalenter Bindung. Salzartige Kohlenhydrat‐Eiweissverbindungen werden aus D‐Glucose‐6‐schwefelsäure und Xylan‐schwefelsäure mit Proteinen erhalten. Die Zusammensetzung der Salze entspricht dem Äquivalenzverhältnis zwischen den Schwefelsäure‐resten der Kohlenhydrate und den basischen Aminosäuren der betreffenden Proteine. Die sich daraus errechnenden Äquivalentgewichte der Proteine sind von der gleichen Grösse wie die nach anderen Methoden gefundenen.
Preparation, properties and structure of polyhydrocarbons derived from p‐xylene and related compounds
Authors: Kaufman Martin H. , Mark Herman F. , Mesrobian Robert B.
Published: April 2003

A pyrolytic dehydrogenation technique originally proposed by Szwarc has been employed for the preparation of polyhydrocarbons from p‐xylylene, pseudocumene, and durene. With particular emphasis on poly‐p‐xylylene, the structure and physical properties of the polymers were investigated. Poly‐p‐xylylene may be obtained in two modifications: a transparent form and opaque form. The transparent form of poly‐p‐xylylene exhibits uniaxial, negative birefringence. The opaque form on purification by chloroform extraction melts at 412°C. Heat treatment of either modification appears to result in an irreversible, polymorphic transition. Poly‐p‐xylylene may be stretched at temeratures above 150°C. to reveal a well‐defined x‐ray fiber diagram, having an identity period of one. Sulfonation of poly‐p‐xylylene yields a product having one sulfonic acid group per benzene ring. The product swells anisotropically but does not dissolve in water. This observation, as well as the observation that the rate of dissolution of poly‐p‐xylylene in high boiling solvents is dependent upon the presence of oxygen, suggest that the polymer is crosslinked to a small but finite extent. The polymer derived from pseudocumene is also crosslinked but contains up to ca. 21% of a chloroform‐extractable component. The number‐average molecular weight of the chloroform soluble component is 23,900.
The half‐life of the styrene free radical. I. Photopolymerization in a free falling stream
Authors: Goldfinger George , Heffelfinger Carl
Published: April 2003

The principle of the method of Paneth and Hofeditz of studying gaseous free radicals has been employed for chain reactions in liquid monomers. The half‐life of a photochemically initiated polystyrene free radical has been found to be 0.088 ± 0.015 second. A simple extension of the technique should also give absolute values of the propagation rate constant and the chain transfer constant.
The absolute turbidities of some pure liquids
Authors: Maron Samuel H. , Lou Richard L. H.
Published: April 2003

Turbidities and Rayleigh ratios have been measured at 25°C. and at wave lengths of 4358 and 5461 A. for benzene, carbon tetrachloride, toluene, and methyl ethyl ketone. The results obtained are in agreement with the theoretical Einstein equation for the scattering of light by pure liquids, the data yielding for Avogadro's number a value of 5.98 × 1023 ± 4.7%, as against the accepted value of 6.02 × 1023. Further, the Rayleigh ratios are in accord with the published measurements of Doty, Zimm, Brice, and their co‐workers, but not with the older literature or the values of Stamm and Button.
Infrared analysis of some chlorinated natural rubbers
Authors: Salomon G. , Van Der Schee A. Chr.
Published: April 2003

Changes in the infrared spectra due to the introduction of 1 to 4 chlorine atoms per isoprene unit in the natural rubber molecule have been studied. Four prototypes are discussed in greater detail: hydrochlorides, rubber dichlorides, chlorinated hydrochlorides, and products obtained by the direct chlorination of rubber and of cyclized rubber. Within certain limits it is possible to follow double bond shifts which occur during the process of hydrochlorination or of chlorination. Chlorinated rubber differs from other chlorinated polymers with a similar composition by a large reduction of the intensity of the CH3 frequency. Absorptions due to the presence of chlorine atoms are observed in the 13–18 μ region, but these bands show little individual differences. Small quantities of oxygen in the form of CO or OH groups are readily detected.
Relative reactivities of polymer radicals in vinyl polymerizations
Authors: Herbst Ralph L. , Martin Robert E.
Published: April 2003

The relative reactivities of polymer radicals in vinyl polymerization have been correlated semiquantitatively according to the Alfrey‐Price Q′ and e scheme. Polystyrene radicals are arbitrarily assigned a Q′r value of unity. The relative reactivities of other polymer radicals are then characterized by the Q′ and e values of the parent monomers. This is shown by data concerned with copolymerization, homopolymerization, and chain transfer. It is proposed that the dispersion forces of London are the predominant influence in chain transfer reactions of polymer radicals with solvents.
Precision rotation viscometer with electrostatic restoring torque for the centipoise range
Authors: Eisenberg H. , Frei E. H.
Published: April 2003

A concentric cylinder rotation viscometer with conical ends was constructed for the measurement of shearing stresses from about 2 × 10−3 to 1.6 dyne‐cm.−2 with a precision of 0.3% at rates of shear from 0.2 to 40 sec.−1. The instrument is intended for the study of dilute high polymer and polyelectrolyte solutions. A stable “suspension” having a negligible frictional torque was obtained by freely floating the inner stationary cylinder in the sheared liquid under investigation. The restoring torque was applied by means of an electrostatic system. Preliminary measurements showed that aqueous solutions of polyvinyl alcohol (du Pont Elvanol 72–60) showed Newtonian behavior at concentrations from 10−2 to 2 × 10−3 g./ml.; aqueous solutions of methylcellulose (Dow Methocel 4000 cps.) of concentration ranging from 10−3 to 4 × 10−5 g./ml. exhibited structural viscosity below rates of shear of 5 sec.−1.
The birefringence of polyisobutylene
Authors: Stein Richard S. , Holmes Frank H. , Tobolsky Arthur V.
Published: April 2003

The variation of stress and birefringence occurring during the relaxation of elongated samples of polyisobutylene at constant length was observed at temperatures between −40° and +50°C. It is found that stress and birefringence relax in the same way throughout this region, and that the quantity (stress/birefringence × temperature) is a constant. This indicates that this material behaves in a manner consistent with the kinetic theories of elasticity and birefringence for an ideal rubber, and that the statistical segment size is fairly independent of temperature in this range. A value of 3.5 × 10−24 cm.3 is obtained for the difference between the principal polarizabilities of the statistical segment.
The significance of some parameters in formulas of polymerization kinetics
Authors: Murphy I. , Wassermann A.
Published: April 2003

A treatment of polymerization reactions is described that involves the assumptions that: (a) intermediates of short lifetime play a role and (b) the velocity coefficients of propagation, (kp)r, and of termination, (kt)r, vary with the chain length, r, of the growing polymers. General formulas are derived and it is shown that they reduce to the previously deduced formulas if the ratio kt/kp is independent of r. Identical formulas can also be deduced, however, if the ratio (kt)r/(kp)r depends on r in a specified manner. Agreement between the previously deduced formulas and the results of experiments does not prove, therefore, that the ratio (kt)r/(kp)r is actually independent of the chain length.
Application of the cell model to the statistical thermodynamics of r‐mers solutions. II
Authors: Bellemans A. , Colin‐Naar C.
Published: April 2003

The cell model for r‐mers and r‐mer solutions developed by Prigogine, Trappeniers, and Mathot is applied to pure diphenyl, diphenylmethane, dibenzyl, and tolan (diphenylacetylene) and to their solutions in benzene. This model introduces new contributions for the excess functions arising from volume changes and modification of the curvature of intermolecular potential with change in composition. The excess functions are written in an explicit form and contain only molecular quantities without any arbitrary parameter. The agreement for the different excess functions (excess free energy, entropy, and excess volume) is satisfactory. The existence of a negative excess specific heat can also be understood on the basis of the cell model and is related to the negative excess volume.
The random chain model for polyelectrolytes
Authors: Harris Frank E. , Rice Stuart A.
Published: April 2003

The random chain model for polyelectrolytes proposed by Kuhn, Kunzle, and Katchalsky is considered. The thermodynamic and configurational properties calculated by Katchalsky and Lifson are shown to be somewhat in error because they have used an incomplete expression for the stretching free energy of the polymer. The agreement of the theory with experiment is not substantially affected in most regions of interest.
Crosslinking in isoprene polymerization
Authors: Morton Maurice , Cala J. A. , Piirma Irja
Published: April 2003

A study has been carried out on the emulsion polymerization of isoprene in an attempt to evaluate the relative rate of the crosslinking reaction and its variation with temperature. From the relation between primary chain length and gel formation during polymerization, the following values were obtained for the relative crosslinking rate constant, i.e., ratio of the velocity constants of the crosslinking and propagation reactions.

Temperature,

°C.
K = kx/kp

60
3.4 × 10−5

70
4.3 × 10−5

80
5.2 × 10−5

The above data lead to a calculated value for the difference in the activation energy between the crosslinking and the propagation reaction (Ex − Ep) of 5.0 kcal. From these data and the known value of the propagation rate constant, it is possible to calculate the following absolute rate expression for the crosslinking reaction itself:

It is noteworthy that the relative crosslinking rate in isoprene polymerization is only about one‐sixth that found for butadiene (K = 2 × 10−4 at 60°C.) apparently owing largely to a higher steric factor. Hence longer chains are possible for polyisoprene before network formation leads to gelation. In the Mutual Recipe, the rate per particle for isoprene polymerization is about three times as fast as for butadiene, although it is still short of the rate found in the ideal low temperature systems.
Some copolymerizations of cis‐ and trans‐Dibenzoylethylene
Authors: Marvel C. S. , Galun Arjeh B.
Published: April 2003

trans‐Dibenzoylethylene has been copolymerized in emulsion with butadiene, 2,3‐dimethylbutadiene, and isoprene. It was found to be of advantage to use low temperatures for the copolymerization with diene monomers, to avoid interference of the Diels‐Alder reaction. trans‐Dibenzoylethylene retarded the polymerization of styrene, but it was incorporated into the copolymer after an induction period. It inhibited the polymerization of vinyl acetate and acrylonitrile which could not be polymerized in emulsions in its presence. cis‐Dibenzoylethylene has been copolymerized with styrene. The incorporation was low (about three per cent), but the viscosities were twice as high as those of polystyrene prepared under the same conditions. cis‐Dibenzoylethylene did not inhibit the polymerization of either butadiene or acrylonitrile and no incorporation of the disketone into the polymer could be proved in either case.
Reduced viscosities of polyelectrolytes in the presence of added salts
Authors: Terayama Hiroshi , Wall F. T.
Published: April 2003

Two different techniques for diluting polyelectrolyte solutions with salt solutions are discussed. The first is the so‐called isoionic dilution and the second is a method using salt solutions of concentrations so chosen as to make the reduced viscosity a linear function of polymer concentration.

For isoionic dilutions, in which the total counterion concentration is kept constant, the reduced viscosity curves are not linear over the whole range but are rather sharply curved at the early stages of dilution. However, it is observed that the viscosity of solutions subject to such dilutions can be expressed by an empirical equation similar in form to that of Fuoss and Strauss.

The second method is carried out by diluting the polymer solution with a simple salt solution whose concentration, c1, is selected by trial and error to make the reduced viscosity a linear function of concentration. The ratio r = c1/c0 where c0 is the concentration of counterions from the original polymer solution, increases as the charge density of the polyelectrolyte decreases and is rather insensitive to c0. The values of 1 − r obtained for the partially neutralized polyacrylate were compared with the degrees of counterion fixation obtained by electrolytic methods, and good agreement was found between the two.
Etude de la polydispersité par diffusion brownienne
Authors: Daune M. , Benoit H. , Sadron Ch.
Published: April 2003

Les auteurs présentent une méthode de mesure des coefficients de diffusion de translation qui permet, dans le cas d'un milieu polydispersé, de définir deux valeurs moyennes D1 et D2. Leur rapport est un critère de polydispersité et, en prenant pour exemple la distribution de Zimm, on discute de la sensibilité de la méthode qui peut en principe mettre en évidence une polydispersité de forme.
Freezing point depression of gels produced by high polymer network
Authors: Kuhn W. , Peterli E. , Majer H.
Published: April 2003

Weakly vulcanized rubber swollen in benzene for one or several days forms a gel whose freezing point is about 5°C. lower than the freezing point of the solvent with which the gel is in equilibrium. This anomaly of the freezing point depression is to be explained by the three‐dimensional network present in the gel, which mechanically prevents the formation of macroscopic crystals. The phenomena observed in the benzene system are compared with similar observations made recently in the case of aqueous gels of polyvinyl alcohol and polyacrylic acid. The benzene system differs from the aqueous system in that an undercooling is observed in the benzene system as well for the formation of crystals outside at the surface of the gel as for the formation of crystals inside the gel. Furthermore, in the case of the benzene system at temperatures below the freezing point of pure benzene a transport of solvent from the inside to the outside of the gel takes place, i.e. a freeze‐drying of the gel is observed. These differences in the behavior of the aqueous and benzene systems are understood as being due to the volume dilation connected with the crystallization of water and the volume contraction occurring in the case of crystallization of benzene. The anomaly of the freezing point depression is a means of characterizing the width of ultramicroscopic structures present in high polymer, essentially also in biological systems.
Gelation of concentrated polyacrylonitrile solutions. II
Authors: Bisschops J.
Published: April 2003

The rate of gelation of concentrated polyacrylonitrile solutions is measured by the increase of the elasticity modulus of the gels with time at constant temperature. The influence of the following factors has been determined : temperature, concentration, molecular weight of the polymer, and water content of the solutions. The rate of gelation increases when the temperature decreases and becomes rapid enough to be measured between 0 and −10°C. The rate of gelation increases further by a factor 150 when the concentration varies from 18 to 23% and by a factor of approximately 3, for a 20% solution, when the molecular weight changes from 100,000 to 150,000. The influence of the water content is such that gelation already takes place at room temperature when the solution contains more than 2% water. The gelation has been ascribed to the formation of crystalline nuclei in the supersaturated solutions and the influence of the factors mentioned above is in agreement with the prediction of the nucleation theory.
A new viscodilatometer with applications to the trommsdorf effect in unsaturated polyester resins
Authors: Gordon Manfred , Grieveson Brian M.
Published: April 2003

A new combined viscometer‐dilatometer is described which requires only small quantities of liquid. The polymerization of unsaturated polyester “contact” resins has been studied, and the “Trommsdorf effect” is shown to be compressed into a sharp kink in the rate curve. This is compared with the form which the Trommsdorf effect takes in a simple methyl methacrylate polymerization, and an explanation for the difference is offered. The breakdown of polymers by mechanical means, and its effect on a system in the vicinity of its gel point, are discussed.
Infrared studies on natural rubber and aged natural rubber
Authors: Dasgupta Sharda , Pande J. B. , Ramakrishnan C. S.
Published: April 2003

In the infrared absorption spectra of solutions of natural rubber in carbon tetrachloride, two new absorptions are observed, one at 6.52 μ and another at 8.2 μ. These bands disappear when films from the solution are examined. Possible origins of these bands are discussed and it is suggested that the absorption at 6.52 μ may be due to a perturbed double bond in a loose complex formed between rubber and carbon tetrachloride. The infrared absorption spectrum of rubber aged in solution also shows these absorptions. However, in the film from aged rubber the 8.2 μ absorption is found to persist. Chemical evidence for the loss in unsaturation is advanced.
Cross‐termination in copolymerization
Authors: Arlman E. J.
Published: April 2003

An attempt is made at giving a quantitative explanation for the variation of the apparent cross‐termination coefficient in copolymerization as a function of the composition of the reaction mixture. The formula developed is applied to the system butyl acrylate‐styrene.
Crystallization and the relaxation of stress in stretched unvulcanized natural rubber
Authors: Tobolsky A. V. , Brown G. M.
Published: April 2003

Decay of stress to zero stress followed by spontaneous elongation occurs in samples of stretched unvulcanized natural rubber in the temperature region of crystallization. Experimental results showing the effect of temperature and elongation on the rate of stress decay are presented.
Relation between the structure of polymers and their dynamic mechanical and electrical properties. Part II. Glassy state mechanical dispersions in acrylic polymers
Authors: Hoff E. A. W. , Robinson D. W. , Willbourn A. H.
Published: April 2003

Some dynamic mechanical properties of a series of polymethacrylic and polychloroacrylic esters have been measured over a wide temperature range at about 200 c.p.s. using a cantilever vibration method. The sharp changes in dynamic modulus, and the associated mechanical loss maxima, which occur at various temperatures are discussed in relation to the chemical structures of the polymers and in particular to the ester group in their side chains. The main softening region is shown to be influenced by the presence of polar atoms in both the main and the side chains and by the spatial size and flexibility of the side chains. The data further support the recently postulated view that a secondary dispersion occurring just below the main softening region is associated with rearrangements of the CO.Ogroup in the side chains. Some new low temperature transitions are reported, one of which at −30°C. is characteristic only of polycyclohexyl methacrylate and polycyclohexyl chloroacrylate; it is suggested that this is associated with intramolecular flexibility within the cyclohexyl ring. Another process occurring at about −150°C. is found for those polymers whose linear side chain alkyl components possess sufficient flexibility to enable them to take up more than one unique spatial configuration; such flexibility is characteristic of the n‐propyl, n‐butyl, and sec‐butyl esters in both series and of the β‐chloroethyl, neopentyl carbinyl, and stearyl esters in the polymethacrylic series. Finally, the strengths of the low temperature relaxation processes, defined in terms of the percentage modulus change, are compared and discussed.
Temperature dependence of mechanical shear degradation
Authors: Goodman P. , Bestul A. B.
Published: April 2003

The rate of mechanical shear degradation of a 10% solution of Vistanex B‐100 polyisobutene (viscosity‐average molecular weight 1,740,000) in cetane has been studied at 60 and 80°C. at high rates of shear. The rate constants for the reaction at a given rate of shear energy application are found to decrease with temperature in this range. This result is interpreted as arising from a decreased efficiency at higher temperatures in the process of temporarily concentrating mechanical energy by means of intermolecular entanglements. The energy input requirements for degradation are found to increase with temperature.
Gelation in addition polymerization
Authors: Simpson W. , Holt T.
Published: April 2003

Recent investigations have shown that cyclization or intramolecular crosslinking plays a major part in the polymerization of diallyl phthalate, and an extension of the network theory of gelation to allow for this led to satisfactory agreement between actual and predicted degrees of conversion at gelation for this monomer. It became important, therefore, to find whether satisfactory agreement could be obtained for other systems, and a detailed examination of the polymerization of the diallyl esters of isophthalic, terephthalic, oxalic, and sebacic acids has now been made. In all of these cases gelation occurs at a conversion higher than the predicted value, the discrepancy being considerably greater than can be accounted for by experimental error. Complicating factors in the interpretation of the experimental results are shown to be absent and it is concluded that cyclization in the poly(diallyl esters) does not affect gelation in the manner expected from theory, and that the satisfactory correlation in the case of diallyl phthalate is fortuitous. It is shown, in the case of the isomeric phthalates which are considered strictly comparable, that all three systems gel at the same degree of conversion, although the ortho ester polymer has considerably fewer pendent allyl groups available for crosslinking and is also of a lower chain length than the other two polymers. This fact seems irreconcilable with the network theory of the gel point as it exists at present. The results are discussed in relation to Walling's diffusion control theory, and although the constancy of conversion at gelation is consistent with the predictions of this theory, supporting evidence regarding molecular complexity is lacking.
Sedimentation and electrophoresis of porous spheres
Authors: Hermans J. J.
Published: April 2003

An approximate method is developed to calculate the velocity of a polymer molecule in a centrifugal and in an electric field. The model used is a porous sphere. The hydrodynamic interaction between the polymer segments is described by means of Oseen's equations. It is assumed that the force acting on the liquid has spherical symmetry and that the flow derived from this force may be replaced by its average over a spherical surface. The results of the calculation show that this approximation is legitimate. For the sedimentation velocity an equation is obtained which is similar to Debye's though somewhat simpler. In the theory of electrophoresis all relaxation effects are ignored, while for the charge density due to the small ions an expression is used that has been derived on the basis of the Debye‐Hückel approximation for electrolytes. The expression derived for the electrophoretic mobility is quite simple and leads to results almost identical with those obtained in previous work by a straightforward extension of the theories of Brinkman and Debye and Bueche.
A study of secondary scattering
Authors: Kraut J. , Dandliker W. B.
Published: April 2003

A quantitative treatment of the influence of secondary scattering on light scattering is presented and experimentally verified. It is shown that secondary scattering accounts for the apparent shortening of the cell dimensions and for the large apparent depolarizations found previously by other workers when using highly turbid solutions as calibration standards. Methods for obtaining the correct calibration constant and depolarization are suggested.
The mode of peroxide‐catalyzed polymerization of vinyltriethoxysilane
Authors: Mixer R. Y. , Bailey D. L.
Published: April 2003

It has been qualitatively demonstrated the vinyltriethoxysilane is polymerized by a free radical process to clear, colorless, viscous liquid polymer of low molecular weight. The low molecular weight is the result of chain transfer with polymer and monomer. This chain transfer involves the abstraction of the alpha‐hydrogen of an ethoxysilyl group (CH3CH2OSi) of either the polymer or the monomer. The ratio of chain transfer with polymer to that with monomer for high conversions is at least 4.5.
Emulsion polymerization of butadiene and styrene in presence of carbon black. I. Persulfate initiation
Authors: Maron S. H. , Von Fischer W. , Ellslager W. M. , Sarvadi G.
Published: April 2003

Butadiene and butadiene‐styrene have been emulsion polymerized in the presence of carbon black and by use of persulfate initiation. The recipe developed gives 50% conversion of butadiene in about 16 hours, and produces polymers which are superior to conventional ones in processability, ultimate tensile, and elongation. The compounded tensiles are about 1000 p.s.i. higher, while the elongations are higher by 60‐100%. The rates of polymerization at 50°C. are dependent on the type of black used, the type and amount of soap, and the method of preparation of the black dispersion, but they are insensitive to molecular oxygen. However, even the “optimum” persulfate recipe suffers from two serious drawbacks: (1) above 50% conversion the rate of polymerization becomes extremely slow, and (2) the stability of the carbon black in the latex decreases rapidly above conversions of 30%. Even though the precipitated carbon black is easily redispersed by agitation, it is inconvenient to work with latices which are so unstable colloidally. These difficulties could not be circumvented in polymerization systems containing persulfate as the initiator.
The copolymer of 2‐methyl‐3‐n‐butyl‐1,3‐butadiene and styrene
Authors: Marvel C. S. , Nowak Robert M. , Passer Moses , Taft W. K. , Labbe B. G.
Published: April 2003

Homopolymers of 2‐methyl‐3‐n‐butyl‐1,3‐butadiene having inherent viscosities of 0.63 to 0.77 have been prepared. These contain 97% of the diene in the 1,4 structure based on perbenzoic acid titration. A compounded and cured 75/25 copolymer of this diene with styrene was found to have very poor properties as an elastomer.
Anomalous relation of apparent viscosity to temperature in high molecular weight polyisobutylene under shear in a capillary viscometer
Authors: Bestul A. B. , Bryant C. B.
Published: April 2003

The apparent viscosities of polyisobutylenes of high molecular weights show extremely high temperature sensitivities in narrow temperature ranges when measured in a capillary viscometer. The temperature at which this anomaly occurs increases as the molecular weight of the polyisobutylene increases. It is higher for a GR‐I rubber than for a polyisobutylene of comparable molecular weight. It decreases with decreasing nominal rate of shear and with increasing radius of the capillary tubes through which the polymer is made to flow at a given average linear velocity. It increases with increasing isotropic pressure on the polymer. This effect is similar to one reported previously for colloidal solutions, and discussed by some investigators as “structure turbulence” occurring at Reynolds' numbers as low as one. It is not caused by crystallization or glass transition. An alternative explanation is that on cooling some relaxation time in the polymer molecules become so long that the molecules cannot orient appreciably in the time they take to pass through the capillaries. The relation between the pertinent relaxation time and the transit time cannot be a simple numerical proportion however.
A compact osmometer
Authors: Yanko John A.
Published: April 2003

A small compact stainless steel osmometer is described that is inexpensive, easy to construct, employs a small quantity of solution, and is capable of producing accurate osmotic pressure data. The capillary tube units are attached to the osmometer by means of leaded threads that give leakproof seals which are reusable. Membrane preparation and osmotic pressure measurements are described. A typical osmotic pressure experiment is illustrated by measurements on dimethyl formamide solutions of a copolymer of vinylidene cyanide/vinyl acetate. The copolymer yielded a number‐average molecular weight of 134,000 and a μ1 value of 0.35 in DMF at 25.00°C.
A solid state polymerization initiated by high‐energy electrons
Authors: Lawton E. J. , Grubb W. T. , Balwit J. S.
Published: April 2003

Hexamethylcyclotrisiloxane monomer polymerizes when exposed to high‐energy electrons. The greatest yield of polymer occurs when the monomer is irradiated in the solid state. Above the crystal melting temperature, the yield of polymer is almost zero for equal irradiation. The polymer obtained is crosslinked. This is unlike the polymerization of acrylamide in which there is extensive polymerization both in the solid and in the liquid state by high‐energy electrons.
The sorption of water by rubber
Authors: Tester D. A.
Published: April 2003

An equation is derived from the consideration of an osmotic mechanism of absorption to represent the absorption–time relationship for a vulcanized rubber immersed in water. The dependence of absorption equilibrium on the relative humidity is also expressed quantitatively. These theoretical relationships are tested for a vulcanized crepe immersed in water and in salt solutions of various concentrations. Good agreement between experiment and theory is obtained for absorption in the absence of air. Divergence from an equilibrium type absorption–time curve in the case in which air is present is shown to be due to aging of the rubber, brought about by oxygen dissolved in the absorbed water. Accelerated aging is shown to be responsible for the marked increase in the rate of absorption brought about by an elevation of temperature, the effect being slight in the absence of air.
Emulsion polymerization of chloroprene. I. Mechanism
Authors: Morton Maurice , Cala J. A. , Altier Mary W.
Published: April 2003

The mechanism of emulsion polymerization of chloroprene has been found to differ considerably from that of other monomers such as styrene or butadiene, apparently due to its exceptional reactivity. Whereas the formation of polymer particles from monomers of low water solubility usually depends largely on the solubilizing effect of detergent micelles, this is not the case for chloroprene. It has been found that dissolved chloroprene and the chloroprene‐water interface may both be active loci for the initiation of polymer particles, depending upon the conditions of the polymerization reaction. It has also been found that chloroprene does not obey the “ideal” kinetics as proposed by the Smith‐Ewart theory, since the rate of particle is not independent of the type and amount of initiator present. Possible reasons for this deviation are suggested.