ALBERT

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

Notes: An osmometer has been constructed in which the only possible transition from one cell to the other is through the vapor phase. In this way the problem of passage of solute is completely eliminated. In order to obtain a sufficient rate of transition of solvent, the distance between the cells has been made as small as possible. An osmometer with a vapor “membrane” of 0.05 mm. thickness is described and measurements with this osmometer are reported.

Notes: Dans le but d'étudier le comportement physicochimique de diverses molécules à chaǐne courte, monodisperses et sans ramifications, nous avons fait une série de mesures viscosimétriques comparatives sur des paraffines normales d'une part, et d'autre part sur des dérivés oxygénés: éthers, dialcoxyalcanes, dialcoxydiéthyléther, etc… Toutes ces mesures ont été effectuées en solution diluée, dans le tétrachlorure de carbone et dans le benzène. Les résultats font apparaǐtre que: (1) Dans le cas des paraffines la viscosité intrinsèque devient négative si la chaǐne comporte moins de dix chaǐnons. Les résultats expérimentaux sont valablement représentés par une loi de la forme [η] = - A + B ln N. (2) Le remplacement d'un CH2 par un atome d'oxygène entraǐne une augmentation de [η]. L'ensemble de nos résultats - paraffines et dérivés oxygénés - peut ětre représenté par une loi de la forme \documentclass{article}\pagestyle{empty}\begin{document}$$ [\eta ] = - A(X_0 ) + B(X_0 )\ln {\rm }N $$\end{document} A et B étant des fonctions du rapport du nombre d'atomes d'oxygène au nombre total de chaǐnons de la chaǐne. (3) Le comportement des deux solvants étudiés à l'égard de tous leurs solutés est rigoureusement comparable.

Notes: A theory of fiber formation from concentrated polymer solutions is presented which is based on the overlap of polymer molecules. The extent of overlapping is estimated from our diffusion measurements (J. Polymer Sci., 19, 337 (1956)). Above a certain concentration, which is lower the greater the size of the individual molecules, the polymer molecules lose their identity and the solution becomes a continuous network. Under these conditions the solution is spinnable and the structure of the network is independent of the molecular weight but depends on the flexibility of the chains. Calculations show that the drawn-out network which forms the fiber has long-range periodicity (100-500 A.) and is in agreement with the order of magnitude observed in smallangle x-ray diffraction of synthetic fibers.

Notes: The experimental study of the dynamic double refraction in polymer solutions in different solvents shows a parabolic dependence of the dynamooptical constant from the refractive index of the solvent. This character of the said dependence can be explained qualitatively in terms of the molecular coil asymmetry; it can be interpreted quantitatively on the basis of the equivalent molecular ellipsoids model. The investigation of the Maxwell effect in a series of polymer fractions with different MW gives the following law: If the refractive indexes, ns and nk of the solvent and polymer are equal, the ratio [n]/[η] is independent of the MW. Here [η] is the dynamooptical constant and [η] is the intrinsic viscosity. If the value of nk - ns is high enough, the ratio [n]/[η] increases as the MW becomes higher and sometimes changes the sign. This law is determined also by the form anisotropy of macromolecules. It agrees well with the theory of equivalent ellipsoids. This theory can be used for the quantitative interpretation of the experimental results. It gives the estimation of the value of the molecular coil asymmetry in agreement with Kuhn's theory. In some cases (e.g., polystyrene in dioxane) the experiment shows change of sign of double refraction as the flow velocity gradient increases. This effect can be explained also by the equivalent molecular ellipsoids theory. As the molecular chains are uncoiling in the field of flow velocity gradient, their intrinsic optical anisotropy increases more than the form anisotropy. The comparative study of photoelasticity in the films of some polymers and of dynamic double refraction in their solutions shows the direct dependence of both effects to be in accordance with Kuhn's statistical theory.

Notes: In laminar flow, polymer molecules are deformed and oriented. The effect is generally observed by investigating the resulting streaming birefringence. From the measurement of the magnitude of the effect, not only the optical anisotropy of the monomer unit, and its dependence on the solvent, but also the uncoiling of the linear macromolecule in the flow can be determined. From the extinction angle, information about the size and flexibility of the coil can be obtained. Since evaluation of the experimental data depends on the special model and on the statistics of the chain elements, an independent check is highly desireble. Light scattering yields such additional information on the size and shape of the deformed macromolecule, information which is less influenced by the special assumptions of the individual models. The pertinent scattering functions are calculated for the freely draining Gaussian coil and for the optically isotropic monomer unit, which in turn allows the determination of molecular parameters i.e., of the main gyration radii from the measurement of the angular dependence of the scattered light.

Notes: On donne les principes d'une théorie générale des propriétés hydrodynaniiques des macromolécules en solution qui utilise comme modèle moléculaire un chaîne subdivisée en N sous-chaînes de Gauss, les frottements du liquide sur la chaîne étant localisés au points de jonction des sous-chaînes. II s'agit d'un modèle déjà ancien, mais qui a été utilisé récemment avec un succès tout particulier par Rouse pour étudier les propriétés visco-élastiques en haute fréquence. Pour édifier une théorie générale à partir de ce modèle nous avons (1) introduit la viscosité interne, (2) tenu compte des interactions hydrodynamiques entre les sous-chaînes. Du point de vue pratique (1) est plus important que (2). L'introduction de la viscosité interne est indispensable pour rendre compte des différents phénomènes qui peuvent se présenter lorsque la solution est soumise à un écoulement (orientation de configurations “figées,” ou déformation). L'effet des interactions hydrodynamiques, de son côté, avait déjà été étudié à l'aide d'un modèle plus détaillé (Kirkwood et Riseman) et I'on avait pu expliquer ainsi les variations de la viscasité intrinsèque avec la masse moléculaire. Si l'on tient compte des interactions hydrodynamiques avec le modèle actuel on n'obtient pas pour I'instant de résultat fondamental supplémentaire. On constate en particulier que la viscosité intrinsèque peut être introduite dans les formules (par exemple dans les expressions de tg α et de Δn en biréfringence d'écoulement); les interactions hydrodynamiqnes ne se manifestent plus alors que par des modifications peu importantes de quelques coefficients numériques. La viscosité interne telle qu'elle est introduite ici diffère dans sa définition de celle de W. Kuhn et H. Kuhn. On définit la rotation instantanée de la molécule en chaîne, puis la défonnation locale instantanée. La viscosité interne s'oppose alors, dans chaque sous-chaîne,à la vitesse de déformation relative des extrémités de cette sous-chaîne. Comme première application de la théorie générale, on étudie les propriétés dynamo-optiques d'une solution monodispersée, infiniment diluée, soumise à un écoulement à gradient de vitesse constant. Les principaux résultats sont les suivants: (a) Grandeur de la biréfringence. Le rapport constante de Maxwell sur viscosité intrinsèque est indépendant de la masse dans une série de polymères homologues. (b) Angle d'extinction. On donne une expression générale (valable pour toutes les valeurs de la viscosité interne) de la pente initiale tg α de la courbe donnant I'angle d'extinction en fonction du gradient de vitesse. Les calculs sont explicités pour les faibles valeurs de la viscosité interne (viscosité η0 du solvant élevée) et pour les valeurs élevées de la viscosité interne (viscosité η0 du solvant petite). On détermine ainsi, respectivement, l'asymptote de la courbe tg α(η0) et la tangente initiale ainsi que le terme de courbure à l'origine. La forme générale de la courbe tg α(η0) est exactement celle qui avait été obtenue par la théorie de la sphère élastique. Ainsi se trouve confimée la possibilité de distinguer entre un effet d'orientation sur des configurations “figées” (ou sur des particules rigides) et urn effet de déformation, lorsque la courbe expérimentale tg α(η0) est connue. On étudie des possibilités de déterminer la viscosité interne par des mesures de biréfringence d'écoulement. Le rapport de la pente de la tangente initiale et de la pente de l'asymptote est très voisin de 10. (Il est indépendant de la nature du polymère et de la masse moléculaire.) Des confrontations avec l'expérience sont ensuite effectuées. On constate que la théorie est susceptible de représenter de façon quantitative les variations de tg α avec η0 dans le cas d'un polystyrène. Un echantillon d'acide désoxyribonucléique montre également un comportement conforme à la théorie.

Notes: Simultaneous measurements of osmotic pressure and permeation of solute have been made for a nonfractionated polystyrene with a number of membranes of widely different permeability. It is shown that, even after many days, no real equilibrium is reached in an osmometer with a membrane permeable to part of the polymer. The theory of equilibria in such osmometers is developed and shows that, in first approximation, the distribution of permeating solute over the two osmometer cells is not affected by the presence of nonpermeating solute. In second approximation, this distribution is affected indeed, but in this approximation the osmotic pressure is not affected by this unequal distribution. Some short-time experiments also show that when the number of permeated molecules is negligible (t → 0) the contribution of a molecular species to the osmotic pressure is less than the value given by equilibrium thermodynamics if the membrane is not completely impermeable to that molecular species. This phenomenon is in accordance with the theory of permeability of membranes based upon nonequilibrium thermodynamics.

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

Notes: Six polystyrene fractions of molecular weights ranging from 1,300 to 250,000 were dissolved in amyl acetate a t various temperatures. The velocity of dissolution was measured by the increase in the refractive index. An assumption was made to describe the experimental results, namely, that the adhesive layer on the surface of solid polystyrene in solvent consists of macromolecular coils the diameter of which can be calculated by Flory's formula. Comparison of the value of the exponent A (from MA) obtained from viscosity measurements with the value calculated from the velocity of dissolution shows excellent agreement. The temperature dependence of the velocity of dissolution is dependent also on the diffusion process of the solvent molecules into the polymer. The expression for this diffusion derived by considering it, as usual, as a rate process, can be introduced into the equation for the velocity of dissolution. The resulting equation accurately describes the experimental results. The velocity of dissolution is different above and below the glass temperature of the polymer. It is possible to use the velocity of dissolution for a determination of molecular weight if the constant of the apparatus has been found by means of a standard sample of known molecular weight. This method helps in the difficult range of molecular weights from 5,000-40,000, where it is very sensitive, whereas other methods are not.

Notes: A rational measure of the heterogeneity of high molecular substances is obtained by comparison of their molecular weight distribution with the theoretical distribution arrived at if infinitely large molecules are depolymerized in such a way that all linkages between the basic molecules are broken with equal ease. This distribution differs noticeably from the error function, which was used by Lansing and Kraemer in measuring heterogeneity. A table is given, by which the distribution curve can be transformed to a straight line. These table values, called “dist” values, are logarithms of the degrees of polymerization in the theoretical distribution, expressed in per cent of the median degree of polymerization. For a fractionated sample, the table values corresponding to the various percentages of substance at which the fractions were obtained are plotted versus the logarithms of the molecular weights. If the molecular weight distribution of the sample is similar to that in depolymerization, a straight line fits the points. The inverse value of the inclination of this line is a measure of the heterogeneity, for which the name heterogeneity quotient is suggested.

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

Notes: On rappelle d'abord les résultats déja obtenus lorsqu'on utilise la méthode interférométrique de Scheibling dans l'étude de la diffusion brownienne de corps polydispersés. On développe ensuite le calcul de trois coefficients de diffusion moyens, qu'on peut relier à des moyens en masses particulières, et qui dans le cas d'une fonction de distribution de forme connue permettent de la déterminer complètement. De plus on peut faire l'analyse complète, a partir de ces trois moyennes d'un mélange de deux espèces différents en proportions quelconques. Quelques exemples expérimentaux montrent les possibilités et la précision de cette méthode. On montre enfin qu'on peut mettre la fonction représentant la courbe expérimentale sous la forme d'un produit de composition, ce qui permet d'obtenir la fonction de distribution par deux transformations de Fourier successives. L'application de ce procédé à une répartition théorique donne un résultat satisfaisant qui justifie une étude expérimentale plus poussée.

Notes: The theories of Hermans and Overbeek, of Kimball, Cutler, and Samelson and of Katchalsky and Lifson concerning the dimensions of polyelectrolyte molecules in solution are discussed. The assumption that the configurational forces acting in a polyelectrolyte molecule may be adequately represented by the theory of nonelectrolytic polymers is applied in different ways by each theory, and leads to widely different results. It is found that, when additivity of the configurational and electrostatic contributions to the free energy is assumed, the configurational contribution is underestimated. The contribution is overestimated, on the other hand, when the potentials of the forces acting on each segment are assumed to be additive.

Notes: By partially quaternizing polyvinylpyridine with n-butyl bromide, a series of polyelectrolytes were obtained in which from Q = 3 to Q = 20% of the pyridine nitrogens were converted to butylpyridinium ions. These products thus are copolymers of ionic and nonionic units. Their conductance was measured over the concentration range 10-4 ≤ c ≤ 3 × 10-3 equivalent of bromide ion per liter in mixtures of methanol and butan-2-one (MEK) ranging from pure methanol to a 20:80 MeOH-MEK mixture. The viscosity of the solvent was thereby varied from 0.00546 to 0.00400 poise and the dielectric constant from 32.6 to 21.6. The phoreograms (Λ-c1/2 curves) are all sharply concave-up, indicating a high degree of association of counterions with the polymeric ions in this range of concentration. The product of equivalent conductance and solvent viscosity gives a dependent variable which accounts for the primary hydrodynamic effect of changing solvent, showing that the ionic mobilities are determined by local viscosity rather than by macroscopic solution viscosity. Plots of log Λη are linear in reciprocal dielectric constant, and therefore ionic association for a given salt is controlled by electrostatic forces. As degree of quaternization decreases, the equivalent conductance increases (other variables remaining constant); this change corresponds primarily to decrease in association of counterions as the charge density of the polycation is decreased. The fact that observed conductances extrapolate to values greater than the single bromide ion conductance in the limits c = 0, Q = 0 shows that cationic sites in the chains are capable of contributing to conductance in alternating fields. Therefore a rigid model represents an oversimplification for the a.c. conductance of polyelectrolytes, although it probably will serve well for d.c. conductance.

Notes: When two or more groups attached to a single chain molecule participate in the formation of an association complex, the equilibrium for complex formation in dilute polymer solution depends on the local concentrations in the swollen polymer coil rather than on the stoichiometric concentration in the bulk of the solution. The theory of intramolecular group association is developed using two models. In the first, the interacting groups are evenly spaced along the polymer chain and the probabilities of their association are governed by Kuhn's statistics of chain configuration. In the second model, every segment of the chain has the same probability of carrying an interacting group and the Kuhn statistics are applied only to large rings, the probability of small ring formation being governed by steric factors. The predictions of the theory are in agreement with the extent of carboxyl association in dilute solutions of seven styrene-methacrylic acid copolymers, measured by infrared spectroscopy. The chelation of cations in dilute polyelectrolyte solution also involves the participation of groups attached to a single macromolecule, but the interpretation of experimental data requires that the electrostatic free energy of complex formation be taken into account. Spectroscopic evidence shows that in copper(II) binding to poly(methacrylic acid) or poly(N, ε-methacrylyllysine) higher complexes are formed than in solutions of simple carboxylic acids or α-amino acids, respectively. Dialysis equilibrium studies indicate that, in the concentration range 4.7 × 10-3 to 15.6 × 10-3 N poly(acrylic acid), the polymer coils act independently of each other in chelating small amounts of copper(II), while the copper (II) affinity of poly(methacrylic acid) molecules drops off with rising polyacid concentration.

Notes: Poly-2-vinylpiperidine and poly-4-vinylpiperidine were prepared from poly-2-vinylpyridine and poly-4-vinylpyridine, respectively, by catalytic hydrogenation at a hydrogen pressure of 3500 p.s.i. and a temperature of 220-250°C., using a palladium catalyst. The hydrochlorides, acetyl derivatives, and phenyl thioureates of the new polymers could also be obtained. The molecular weights of the polymers were estimated by light scattering and viscosity in chloroform and methanol solution and were found to lie in the range of 10,000 to 35,000. The electrochemical properties were investigated by potentiometric titration and electrophoresis. From the character of the titration curves it was concluded that no appreciable nearest neighbor interaction exists in polyvinylpiperidine. By an analysis of the combined potentiometric-electrophoretic data an intrinsic acid dissociation constant pK0 = 10.08 ± 0.07 was calculated. The discrepancy between this value and the value of the dissociation constants of monomeric piperidines, pK ≈ 11, has been further investigated by thermochemical measurements.

Notes: Viscometric data obtained over a temperature range of 0-150°C. for a series of salicyloxymethyldimethyl end-blocked dimethylpolysiloxane fluids have shown that the molecular weight at which a minimum viscosity is exhibited is temperature-dependent. Thus, with decreasing temperature, minimum viscosities were manifested at higher molecular weights. With increasing molecular weight, i.e., increasing siloxane character, the energy of activation of viscous flor (Evisc) not only decreases, but also is less temperature dependent. An empirical expression relating Evisc and temperature for such fluids is presented.

Notes: The capacity of cells containing solutions of 5% cellulose acetate in dioxane was measured from 50 cycles to as high as 5 megacycles by a bridge method. A dispersion region was found between zero and approximately 40 kc. The frequency where the dielectric dispersion was 0.50 was taken as the critical frequency which was found to be related to the viscosity determined degree of polymerization. An empirical correlation enabled the calculation of degrees of polymerization from dielectric dispersion which could be readily duplicated and which agreed reasonably well with those found by the viscosity method. It is suggested that this procedure may develop into a very convenient and rapid method for molecular weights pending the accumulation of further experimental evidence.

Notes: Glass transition temperatures (Tg) and thermal expansion coefficients (α) above and below Tg have been determined for gels of cellulose tributyrate in dimethyl phthalate (weight fraction polymer, w2, of 0.20 and 0.43) and of cellulose nitrate in diethyl phthalate (w2 = 0.12 to 0.37). Below Tg, α increases with w2; above Tg, α decreases with increasing w2. In the tributyrate (w2 = 0.43) a second transition appears, as noted by Mandelkern and Flory for the undiluted polymer. By combining the Tg values with the coefficients of the WLF equation, the quantities fg and αf are calculated for the tributyrate gels. Here fg, interpreted as the relative free volume at Tg, is about 0.020; while αf, interpreted as the expansion coefficient of free volume relative to the total volume, is 4.8 × 10-4 deg.-1, approximately equal to the macroscopic change in α at Tg.

Notes: A number-average property such as a number-average diffusion constant Dn cannot be defined in terms of weight-related weighting factors (such as concentrations in weight per unit volume) without postulating a functional relationship between the molecular weight and that property. Conversely, an analogous statement holds concerning any weight-average property and number-related weighting factors such as mole fractions. Ordinarily the molecular weight distribution is not known initially for a given sample under study, so that assignment of any such a relationship under these circumstances would be quite arbitrary. It is proposed that the number average analog [Σci/(Σci/Qi)], which is equal to the true number average Qn only when Qi is directly proportional to the molecular weight Mi within the sample considered, be designated the number-analogous average Qx to distinguish it from Qn. (In this, ci is a weighting factor proportional to the polymer weight fraction having the value Qi of the intensive physical or chemical property under discussion.) Mn is of course necessarily equal to Mx. However, designation of Dx as the number-average diffusion constant is particularly unreasonable because it implies direct proportionality between the molecular weight and the diffusion constant. Although such a relation may hold for a specific case, in general, other factors being usual, the diffusion constant is inversely related to molecular weight. Discussion of a specific illustration shows the following: Qx may be the same for heterogeneous systems having different values of Qn. Qn cannot in general be found by analyzing a material distribution by means of a property such as the refractive index that is proportional to the mass concentration rather than to the number of molecules in a given volume. Qx sometimes can be found from such data. Although the sedimentation and diffusion constants, with the partial specific volume, define the molecular weight of a homogeneous sample, the average sedimentation and diffusion constants of a mixture do not uniquely determine its average molecular weights. Values found from weight-, number-, or number-analogous average sedimentation and diffusion constants may be either higher or lower than the weight- and number-average molecular weights, even though these latter have been deduced to be limiting values for certain postulated molecular weight distributions. In a given instance, heterogeneity indexes calculated from true weight- and number-averages of sedimentation and diffusion constants more closely approximate the ratio of the weight-average to number-average molecular weights than if the more readily determined number-analogous averages are used.

Notes: Methods of synthesizing linear polyesters from fluorine-containing diols have been investigated. The most suitable method consists of reacting the fluorine-containing diols with dicarboxylic acid chlorides. Number-average molecular weights in excess of 15,000 have been obtained. The polymers are rubberlike gums or waxy solids, depending on the reactants used. Increasing amounts of fluorine, contained either in a pendent group or on the backbone chain of the polymers, decreases their solubilities in common solvents, and raises their brittle temperatures.

Notes: Polymerization of acrylonitrile in dilute aqueous solution initiated by the chloratesulfite redox was studied kinetically and with the aid of the electron microscope. Polymerization rate depended on the [ClO3-] [H2SO3] product, the monomer content and the sodium lauryl sulfate concentration. The rate was depressed by agitation and by salts; it was accelerated by Fe++ and by Cu++ and was only moderately dependent on temperature. Particles of polymer separated from the start as spheroids less than 200 A. across and grew rather uniformly to 2000 to 3000 A. After a short time no new particles formed unless more initiator was added. Rate of polymerization per particle was reasonably constant. Salts and agitation led to aggregation of particles and polymerization rate was reduced. Sodium lauryl sulfate and Methocel had the opposite effect. The system bears a general resemblance to typical emulsion polymerization, and thus treatments based on homogeneous kinetics appear to be inadequate.

Notes: A study has been made of crystallization phenomena in nylon 66 occurring after fusion at temperatures just above the melting point. It appeared to be possible to obtain optically negative spherulites in nylon 66 by crystallizing at temperatures between 250 and 258°C., after fusion at temperatures above 258 but below 265°C. The radial growth rate of the negative spherulites has been determined and has been found to depend on the crystallization temperature. The optically negative spherulites have a higher optical melting point than the optically positive spherulites hitherto observed in nylon 66. Another type of spherulitic structure with spherulites of a fibrous appearance, of which the optical sign cannot be determined, is reported. An attempt is made to explain the data obtained on the basis of the generally accepted crystallization mechanism, valid for linear high polymers.

Notes: The knowledge of the physical chemical properties of cellulose and the laws of their alteration during the growth of natural filaments is very important for scientifically increasing the production of natural cellulose filaments. While dealing with cotton growing we have been continuously performing the physical chemical investigation of natural cellulose. The results obtained may be summarized as follows. Cellulose appears in the cotton tissue together with the flower and pod and not several days after blossoming, as is the general opinion to be encountered in the literature. The synthesis of cellulose in cotton is at first very slow, showing an acceleration by the 15th day after bloom with a subsequent slow-down again and complete cessation approximately on the 40th day after bloom. Thus the characteristic curve of cellulose accumulation in cotton has an S-shaped form. The natural cellulose of an early age has a very low degree of polymerization which later, by the 25th to 30th day after bloom, shows an abrupt increase and remains almost stable. The filament then almost completely consists of α-cellulose. The kinetics of the polymerization and accumulation of cellulose is connected with the ripening period of cotton under investigation and makes it possible to predict the time of the ripening of pods. Early cellulose is very porous, it easily hydrolyzes, and has a higher sorption capacity and heat of solution than the cellulose of a mature age. However, the tightness of packing of the natural cellulose evaluated in terms of water sorption and heat of solution in water, reaches its maximum in the vegetation period, i.e., approximately on the 40th day of the maturation of filaments. The gradual increase in tightness of cellulose packing and its drop after 40 days can be accounted for if we consider the possibility of synthesis in all layers of the secondary wall of the filament, i. e., throughout the tissue of cellulose and not only in the channel of the filament. The main physicochemical and technological properties of cellulose bodies are the functions of the tightness of molecular packing of cellulose. The tightness of packing may vaccilate within a very broad range depending on the conditions of biosynthesis or processing.

Notes: Poly-ε-aminocaproyl-DL-alanine, [—HN(CH2)5COHNCH(CH3)CO—]n, was prepared by the polymerization of N-carbothiophenyl-ε-aminocaproyl-DL-alanine. The copolymer synthesized precipitates from an aqueous saturated solution on heating (40 to 60°). The precipitate formed goes back into solution on cooling. Repeated precipitation and dissolution by change of temperature show that the heat coagulation is reversible. The coagulation phenomenon discussed is pH-dependent, but practically independent of ionic strength or the presence of denaturing agents such as urea. The ability of the following polymers to coagulate from an aqueous solution on heating was investigated: H—[—HN(CH2)mCOHNCH(CH3)CO—]nOH (I), m = 1,2,3,4,5; and H—[—HN(CH2)m—CO—]nOH (II), m = 1.2,3,4,5. None of the polymers investigated, except poly-ε-aminocaproyl-DL-alanine (I, m = 5) showed reversible heat coagulation. The polymers of group I dissolve in water more readily than those of group II. The aqueous solutions of I, m = 1; I, m = 3; and II, m = 1, give a distinct positive biuret reaction. In a series of copolymers of α-amino acids with ε-aminocaproic acid it was observed that reversible heat coagulation in water occurs in copolymers containing L-proline or α-aminoisobutyric acid, but not in copolymers containing glycine, L-leucine, or L-phenylalanine. Reversible heat coagulation was also observed in the case of poly-L-proline.

Notes: The matrix method which has been employed in the theory of ferromagnetism is potentially very useful in treating statistical problems concerning linear macromolecules with repeating units. The method is reviewed briefly and applied to seven illustrative problems (two of which are not worked out completely). Six of these involve ion binding or titration curves of polyelectrolytes and one has to do with the question of imperfections (missing hydrogen bonds) in the α-helix.

Notes: On a mesuré l'influence de l'acide polyméthacrylique ajouté aux solutions concentrées de NaCl, NaBr, NaI sur la réfraction moléculaire de ces sels. On trouve que la présence d'acide polyméthacrylique cause une diminution de réfraction moléculaire des sels qu'on ne peut pas expliquer seulement par la concentration du polymère.

Notes: This paper reports light scattering and viscosity data concerning a fraction of lithium polyphosphate of high molecular weight (1.0 × 106) dissolved in LiCl solutions whose concentration varied from 0.025 to 0.4 M. The lithium polyphosphate was obtained by adding a cation exchanger (Dowex 50, lithium form) to an aqueous suspension of insoluble potassium Kurrol's salt. The higher fraction of the dissolved product was then precipitated by adding an alcoholic solution of LiCl. The root mean square end-to-end distance of the polyelectrolyte molecule, (r2), as obtained from the angular dependence of the scattered light, is as much greater as the ionic strength lowers. The Fox-Flory relation can be applied in the above range of ionic strength. The second virial coefficient becomes zero at a ionic strength of about 0.4, and the ratio (r20/M)1/2 = 1.24 × 10-8cm. shows that the molecule has a low flexibility. The dependence of the expansion coefficients and of the second virial coefficients on ionic strength is discussed, use being made of the theories concerning polyelectrolyte behavior.

Notes: The viscosity of dilute aqueous solutions of polyelectrolytes has been reinvestigated with the help of an improved model of a rotation viscometer with electrostatic restoring torque recently described. The experimental variables included rate of shear, composition of the medium, concentration, and degree of polymerization of the solutes. The limiting slopes of the viscosity numbers of polymethacrylic acid as a function of the rate of shear have been found to be horizontal, in accord with hydrodynamic theory. The limiting viscosity numbers of fractions of polymethacrylic acid, poly vinylpyridiniumbutyl bromide and sodiumcarboxy methylcellulose are analyzed. A discussion of experimental methods used for the study of rate of shear dependence of the viscosity of polyelectrolytes is given.

Notes: Specimens of sodium alginate have been investigated dielectrically in aqueous solution at low concentrations. The effect on the dielectric increment and dispersion of concentration of polyions and counterions, isoionic dilution, degree of polymerization and degree of neutralization of polyions, and the dielectric constant of the solvent has been studied mainly. Qualitative interpretation of the data in accordance with the present polyelectrolyte theory as Maxwell-Wagner or Debye-Falkenhagen effects has been attempted.

Notes: The copolypeptide of L-lysine, L-leucine, and L-glutamic acid, and that of DL-lysine, DL-phenylalanine, and DL-glutamic acid were studied by surface pressure and surface viscosity measurement. The relationships between ionization and monolayer properties were thoroughly studied. The monolayer of poly-L-glutamic acid was also investigated. These polyelectrolytic monolayers were affected by pH of the substrate and the concentration of salt in it. The monolayer behavior could be interpreted in terms of effective free charges and the number of salt linkages. The two-dimensional Donnan equilibrium was applied to the polyelectrolyte monolayer. The derived relation is formally identical to that derived by Davies from an entirely different point of view.

Notes: Nous avons utilisé dans notre étude de l'effet électrovisqueux des suspensions aqueuses de noir de carbone, très stables, obtenues après traitement chimique. Ces suspensions contiennent des particules de noir de carbone de forme approximativement sphérique, parafaitement rigides et qui portent en surface des groupements chimiques qui leur confèrent le caractère de polyélectrolyte. Nous avons étudié la viscosité de la solution lorsque l'on fait varier la constante diélectrique ε du milieu dispersant soit par addition à l'eau d'un solvant miscible de basse constante-diélectrique tel que l'alcool éthylique, soit par variation de la température. Nous avons également étudié l'influence sur la viscosité de l'addition au milieu de dispersion de sel neutre (KCl) d'acide fort (HCl) et de base forte (KOH). En dehors des observations viscosimetriques on a noté qu'il y a floculation reversible du sol lorsque l'on diminue suffisement ε, tandis que le sol ne flocule pas en milieu KOH, quelle que soit la concentration en KOH. Ces deux observations ne semblent pas avoir de précédent. Le comportement du sol en milieu KCl est classique, c'est-a-dire qu'il y a floculation pour des concentration suffisantes en sel. La floculation apparait plus vite par addition d'HCl que de KCl. On peut tirer de l'étude les conclusions suivantes: (1) Les résultats expérimentaux mettent en évidence un accroissement de viscosité provoqué par l'apparition de ce que l'on a dénommé la “floculation limitée” phénomène qui ne se manifeste pas sur l'état apparent du sol et que décèle seulement l'augmentation de K. Ce phénomène sera suivi de la floculation proprement dite si l'on continue à abaisser ε ou à augmenter la concentration ionique. On propose une explication simple de la floculation limitée et de l'accroissement de viscosité qui l'accompagne. (2) Dans le domaine où les sol est soumis au seul effet électrovisqueux la théorie de Booth permet une interpretation satisfaisante des résultats viscosimetriques. (3) Les résultats obtenus montrent que la stabilité du sol étudié dépend nettement de la grandeur de la charge portée par les particules et de l'épaisseur de la double couche approximée par le paramètre x-1 selon Debye.

Notes: Il est bien connu que l'on peut obtenir au départ de mesures de la pression superficielle les poids moléculaires et les cosurfaces des molécules étalées sous forme d'un film mono-moléculaire. Nous avons essayé d'établir une rélation étroite entre les cosurfaces spécifiques et les dimensions linéaires des molécules. On montre ainsi que dans le cas de deux protéines à dissymétrie élevée, la gliadine et la zéine, il existe une relation linéaire entre les cosurfaces spécifiques et le poids moléculaire. En combinant les résultats de la pression superficielle à ceux de la densité moléculaire il est possible de calculer le rapport des axes. Les résultats sont en bon accord avec ceux indiqués par d'autres méthodes.

Notes: The dependence of the degree of ionization of highly swollen, crosslinked polyelectrolyte gels (immersed in salt solution) on the pH of the external equilibrium solution was investigated. A potentiometric equation was derived theoretically, comprising an ideal term, a Donnan term, and a term due to polyelectrolyte electrostatic interactions. Measurements were carried out with polymethacrylate gels in solution of LiCl, NaCl, or KCl. No difference in behavior was found with the different cations, and the observed dependence of the titration curves on ionic strength, degree of crosslinking, and degree of swelling was satisfactorily accounted for by the theory.

Notes: The alkaline and acid hydrolyses of polyvinylamides and their N-substitution derivatives have been studied and compared to the alkaline and acid hydrolyses of simple homologous substances. The rates of reaction have been followed conductometrically, and the rate constants evaluated at different temperatures in order to determine the energies of activation and the log PZ of the Arrhenius equation. The influence of the polymeric structure on the course of the reactions has been shown. In alkaline medium the increasing negative charges on the polymeric chain exert an electrostatic repulsion effect toward the hydroxyl ion, and, as a consequence, cause a progressive decrease of the rate of reaction. In the case of polyacrylamide (PAA), hydrolysis enhances an uncoiling of the polymeric chain when the degree of conversion reaches about 40%. Therefore the reaction is characterized by two different steps, a first, rapid step analogous to the reaction of aliphatic monoamides (Ea = 13.7 kcal.), and a second, slow step related to the increasing electrostatic effect. This interpretation has been confirmed by hydrolysis measurements on copolymers of acrylamide-vinylpyrrolidone (42/58) and acrylamide-acrylic acid (64/36). In the case of polymethacrylamide (PMA), N-methyl-PAA, and N,N′-diethyl-PAA steric hindrance along the chains confers a stretched configuration on the macromolecules, and reinforces the electrostatic effects; therefore, the rate constants, can be determined only at low degree of conversion. Moreover, the maximum degree of hydrolysis becomes limited and is 72, 55, and 35 for PMA (Ea = 16 kcal.), N-methyl-PAA (Ea = 18.3), and N,N′-diethyl-PAA (Ea = 22 kcal.), respectively. N,N′-Diethylpolymethacryamide is completely alkali-resistant. In acidic medium the hydrolysis of PAA and PMA is characterized by a secondary intramolecular cyclization due to imide formation between amide and acid functional groups. This secondary reaction, which becomes appreciable at 85°C., causes an increase in the overall energy of activation of the hydrolysis, which is consequently 3 to 4 kcal. higher than those of aliphatic low molecular weight compounds. On the other hand, this imidization is absent in the case of the N-substituted polymers, of which the energies of activation are equal to those of the aliphatic homologous substances (N-methyl-PAA = 21.7; N,N′-diethyl-PAA = 24.6 kcal.).

Notes: The Hofmann degradation reaction has been applied to polyvinylamides in order to obtain aminocarboxylic polyampholytes. When the reaction is effected in aqueous solution, interactions occur between isocyanate and neighboring chloroimide ions, with the formation of butyrolactam ring units incorporated in the polymeric chain. The structural composition of the polymers has been determined on the basis of the following analytical results: total and volatile nitrogen, total and ionic chlorine, and conductometric and potentiometric titrations. In the case of polymethacrylamide the end product consists of about 57% lactam rings, 28% free amine chlorohydrate, and 8% methacrylic acid units, while about 5 to 6% amide groups remain unreacted. In the case of polyacrylamide the degree of conversion is usually lower; this difference in behavior has been interpreted as being due to the high substitution in the methacrylic derivative. When the reaction is effected in water-methanol (50/50) solution, any ring formation is absent; contrariwise, the isocyanate functions are transformed into carbamate units. In alcoholic medium it is possible to obtain polymers containing about 50% carbamic functions, as well as small amounts of free amines (3%); the residual percentages are acid or unreacted amide groups. On alkaline hydrolysis of these carbamic functions, free amine functions are produced; however, the rate of hydrolysis is very low if compared to that of usual amides. This effect has been attributed to the nitrogen substitution in the carbamate units and to the electrostatic repulsion effect of the carboxylate functions toward the hydroxyl ion. For verification, the alkaline hydrolysis rate constants of N-isopropyl methylcarbamate have been compared with those of methylcarbamate; they were found to be about ten times slower. Moreover, the corresponding activation energy of alkaline hydrolysis was 18.7 kcal./mole instead of 14.1 in the case of the unsubstituted methylcarbamate. The products obtained by Hofmann degradation on polymethacrylamide have been compared to those obtained by Lossen rearrangement reaction on polymethacroyl chloride; the structural units were found to be identical in both cases.

Notes: Experiments are reported on the rate of polymerization of N-vinylpyrrolidone in the presence and in the absence of azobisisobutyronitrile as initiator. The reactions of N-vinylpyrrolidone in aqueous acid solution are mentioned. The limited degree of swelling of crosslinked polyvinylpyrrolidone is discussed. Degree of swelling is influenced by choice of solvent, by temperature and, in aqueous systems, by ions which are present on the network of the gel. These ionized groups can be introduced by copolymerization with unsaturated acids or by adsorption of ions from solution. Certain dyes are especially suitable for the formation, in this way, of polyelectrolyte gels having a low charge density.

Notes: The complex dielectric constant of a pure molecular weight fraction of poly-n-butyl methacrylate was determined over a frequency range of 30 to 3 × 105 cps. and a temperature range of -74 to 114°C. The d.c. volume resistivity-temperature behavior was also determined. The data indicate the presence of two transition regions. Comparison of these data with those on polyethyl methacrylate shows that the transitions in the butyl polymer are further apart in temperature than in the ethyl polymer. Further, the data show that the ethyl chain is stiffer than the butyl chain. An attempt at superposition of the normalized complex dielectric constant was unsuccessful. Calculation of the distribution function of relaxation times for several temperatures shows a marked temperature dependence of this function.

Notes: The temperature-dependence of specific volume, rigidity modulus, and mechanical losses of plasticized and unplasticized cellulose acetates in the temperature range -100 to +200°C. has been studied. Two cellulose acetates, a triacetate and a cellulose (2.2) acetate were used, these being plasticized with varying amounts of either benzyl acetate, m-cresol, o-ethylphenol, γ-butyrolactone, monomethylaniline, benzylphenol, or Santophen 7 (a phthallyl glycolate). The specific volume measurements, made using an extremely sensitive dilatometer, indicated three apparent second-order transitions and one first-order (melting) transition in cellulose triacetate and three or possibly four apparent second-order transitions but no first-order transition in the cellulose (2.2) acetate. Both the first-order and second-order transitions were depressed by the addition of plasticizer, the depression being most marked with the phenolic-type plasticizers. Because of polymer decomposition at temperatures above 200°C., it was not possible to study the melting of mixtures containing less than 30% plasticizer and subsequently no reliable values for the melting temperature, the entropy, and the heat of crystallization could be determined. Rigidity modulus measurements, obtained using a torsional pendulum technique and the mechanical loss (damping) measurements, confirmed the existences of these second-order transitions in both acetates and indicated that only the highest temperature transition, 175°C. in the triacetate and 195°C. in the secondary acetate, had the characteristics of a normal glass to rubber transition.

Notes: Polymers and copolymers of a quaternary monomer, vinylbenzyltrimethylammonium chloride, have been studied. A product similar to that previously obtained by partially chloromethylating polystyrene and aminating with trimethylamine has been made. The product with 15 to 25 mole per cent quaternary groups forms metastable aqueous solutions. Light scattering measurements in the presence of added salt do not indicate aggregation. The quaternary monomer exhibits micellar behavior in conductivity measurements. Copolymers with acrylamide are water-soluble and substantive to paper pulp; copolymers in minor amount with acrylonitrile are dyeable with acid dyes; copolymers in minor amounts with styrene are clear and free of tendency to pick-up or maintain a static charge.

Notes: 4-Vinyl-1-cyclohexene and d-limonene have been converted to dimercaptans by the addition of thiolacetic acid and subsequent hydrolysis. These dimercaptans have been added to the original nonconjugated diolefins to give low melting highly viscous polymers. In the case of 4-vinyl-1-cyclohexene two monoaddition products of thiolacetic acid have been isolated and characterized. The ratio of the two products indicates two parts of adduct to the cyclohexene double bond to three parts of adduct to the vinyl group double bond are produced in the addition reaction.

Notes: The study of the polymerization of nitroethylene in methyl ethyl ketone and catalyzed by bases of the pyridine series - as reported in part I - was extended in the present work. The MW of a number of polymers was determined by a semimicro cryoscopic method, which is described in detail. Of all the reaction parameters, at 20°C., the MW was found to depend only on the initial monomer concentration. To account for this dependence, an additional step was included in the three-step mechanism suggested earlier, namely, that of catalyst transfer to monomer. Spectroscopic examination of the polymers support the suggestion that termination, or transfer, is accompanied by ring closure and the formation of cyclic structures.

Notes: The polymerization of α-methylstyrene catalyzed by sodium naphthalene has been studied below 0°. Measurable amounts of monomer remained in equilibrium with the polymer down to -40°, even though the color indicated that active chain ends were still present. This behavior is expected of α-methylstyrene since, due to a low heat of polymerization, the reverse of the chain propagation step must be important at these temperatures. From the equilibrium monomer concentrations determined experimentally, the heat and entropy of polymerization of α-methylstyrene has been calculated.

Notes: An x-ray diffraction study has been made of cellulose triacetate II. Small films of highly crystalline triacetate with good fibrous orientation and a fair degree of biaxial orientation have been prepared by repeated rolling at successively higher temperatures between 160 and 215°C. The x-ray diffraction patterns exhibited several new reflections which made it possible to determine the unit cell. It has been found that cellulose triacetate II has four cellobiose acetate residues in a pseudo-orthorhombic cell with a = 24.5, b = 11.56, and c = 10.43 A. Pairs of these residues are related by twofold screw axes in the c or fiber-axis direction. The paired arrangement seems to be determined by a fitting of the natural zigzagging shape of the cellulose backbone which is exaggerated by the presence of the secondary acetyl groups. The glucose residues of such a pair are parallel and inclined at about 45° with respect to the a axis. A neighboring chain pair points in the opposite direction and the median planes of the cellobiose units of two such pairs are approximately mutually perpendicular. To accommodate this type of packing, one half of the primary acetyl groups must be twisted sharply out of the median plane of the parent glucose residues. A second statistical model which basically is very similar is also considered. There do not appear to be any strong interactions between chains.

Notes: The well-known Zimm plot can be modified by plotting Kc/Rϑ sin2 (ϑ/2) against 1/sin2 (ϑ/2) with concentration c as a parameter, which gives a series of straight lines with a common intercept. By extrapolating to zero concentration one can determine the weight-average molecular weight from the reciprocal of the slope and the radius of gyration from the common intercept on the ordinate. This method finds applications for macromolecules having very high molecular weights.

Notes: Es werden Darstellung und Eigenschaften von Polyacrylsäurehydraziden beschrieben. Salzbildung und Reaktionsfähigkeit entsprechen denen niedermolekularer Säurehydrazide. Polyacrylsäurehydrazide bilden mit Aldehyden und Ketonen makromolekulare Hydrazone, mit salpetriger Säure explosive, makromolekulare Azide.

Notes: Durch Polykondensation unter Abspaltung von Äthylacetat wurden Organo-Hetero-Polysäureanhydride von Silizium, Zinn, Bor und Phosphor dargestellt und ihre Eigenschaften beschrieben.

Notes: Die Mannigfaltigkeit der Bedingungen, unter welchen Polymerisationsprozesse ablaufen können, macht eine rationelle Gliederung notwendig. Hier wird der Versuch unternommen, eine Klassifizierung der Polymerisationsprozesse unter kolloidchemischen Gesichtspunkten zu geben.Die bei der Polymerisation zur Anwendung kommenden Emulgatoren und Initiatoren können öllöslich, wasserlöslich oder unlöslich sein. Durch die Eigenschaften dieser Molekül-, Mizell- und Phasenkolloide werden die kolloidchemischen Polymerisationsbedingungen bestimmt.Polymerisationsprozesse in Lösung ohne Emulgator sind einphasig. Polymerisationsprozesse mit löslichen Emulgatoren vollziehen sich in zweiphasiger Emulsion.Unlösliche, feste Emulgatoren lassen Polymerisationsprozesse dreiphasig ablaufen.Im Gegensatz zu molekulargelösten (öllöslichen und wasserlöslichen) Polymerisationsinitiatoren, die die Zahl der Phasen nicht verändern, wird durch feste Polymerisationsinitiatoren die Zahl der Phasen erhöht und der Polymerisationsprozeß selbst in die Grenzflächen der Phasen verlegt, unter welchen die Grenzschichten Fest-Flüssing, Fest-Gas und Flüssig-Flüssig von besonderer Bedeutung sind.Die kolloidchemische Bedeutung der Phasengrenzfläche Fest-Flüssig für die stereochemische Polymerisation wird eingehend diskutiert.Die Systematik scheint auch eine rationelle Verschlüsselung für Hollerith- oder Randlochkarten zu gestatten.

Notes: In der vorliegenden Studie werden drei röntgenographische Beobachtungen beschrieben, in welchen offenbar charakteristische Merkmale der übermolekularen Struktur von Vinyon N zum Ausdruck kommen: 1Die Orientierung, die im Kleinwinkeldiagramm zum Ausdruck kommt, eilt deutlich jener voraus, die dem Faserdiagramm zu entnehmen ist.2An bestimmten Präparaten wird im Zustand mäßiger Quellung eine scharfe Interferenz beim Bragg'schen Wert von 171 Å beobachtet.3Die Orientierung im Weitwinkeldiagramm erreicht bei etwa 600% Dehnung einen Wert, der bei weiterer Dehnung nicht mehr verändert wird. Die Halbwertsbreite beträgt etwa 15°.Außerdem haben wir versucht, die diffusen Kleinwinkeldiagramme hochgequollener Präparate (verdünnter Systeme) im Sinne der Theorien der Partikelstreuung auszuwerten und konnten “Streuungsäquivalenz” mit Zylindern feststellen, deren Durchmesser etwa 114 Å beträgt und deren Länge mit zunehmendem Quellungsgrad von etwa 200 auf etwa 140 Å abnimmt. Während wir der Auffassung sind, daß der Durchmesser der Hauptmenge der Teilchen nur wenig um diesen Wert schwankt (wobei die Streuung bei kleinsten und größten Winkeln Hinweise auf die Anwesenheit nicht unerheblicher Mengen an sehr großen und sehr feindispersen Anteilen gibt) muß im Hinblick auf allgemeine Vorstellungen von der übermolekularen Struktur makromolekularer Systeme die Möglichkeit offen gelassen werden, daß es sich bei der berechneten Länge wirklich nur um Streuungsäquivalenz handelt und in Wahrheit besser und schlechter geordnete Bereiche abwechseln, die gegeneinander verwinkelt sein können, wobei aber die Länge des “streuungsäquivalenten Ersatzkörpers” sowohl von der wahren Länge vor allem der besser geordneten Bereiche, als auch der Gestalt dieser micellaren Stränge als Ganzes abhängig ist.Zur vollständigen Klärung des übermolekularen Aufbaues werden noch weitere sehr ausgedehnte Studien erforderlich sein.

Notes: 1Lineare Oligoester der Terephthalsäure und des Glykols bilden die polymerhomologen Reihen der Ester-diole,Ester-dicarbonsäuren,Ester-oxysäuren.2Von den Esterdiolen wurden die ersten vier Vertreter bis zum tetrameren Diol dargestellt.3In der Reihe der Esterdicarbonsäuren wurden die mono- und die dimere Verbindung in Form der Dimethylester synthetisiert.4Die drei ersten Glieder der Esteroxysäuren wurden synthetisiert und Derivate dargestellt.5Die van der Wyksche Regel, die es erlaubt, die Schmelzpunkte der geradkettigen Paraffine zu berechnen, läßt sich auch auf die oligomeren Terephthalsäureglykolester übertragen, wenn geeignete Konstanten eingesetzt werden.6Die röntgenographische und infrarotspektroskopische Untersuchung der Oligoester zeigt, daß wichtige physikalische und chemische Eigenschaften der Polyterephthalsäureglykolester bereits in einigen niedermolekularen Verbindungen angetroffen werden. Die Röntgendiagramme und Infrarotspektren weisen schon vom trimeren Diol ab eine weitgehende Übereinstimmung mit der makromolekularen Verbindung auf.

Notes: In der Absicht, die vermutliche Wirkung der Kristallinität auf den Mechanismus der Fraktionierung zu untersuchen und sie auch möglichst auszuwerten, sind vier Hochdruckpolyäthylene verschiedener mittlerer Polymerisationsgrade nach drei Methoden fraktioniert worden.Eine dieser Methoden (C), die fraktionierte Fällung mit Polyoxyäthylenglykolen, die durch Verteilung des Polymeren zwischen zwei flüssigen, nicht mischbaren Phasen entsteht, zeigte eine große Überlegenheit.Die anderen zwei Methoden, die aus einem Gleichgewicht zwischen einer Sol-Phase und einer teilweise kristallinen Gel-Phase entstehen, geben eine ganz verschiedene und wahrscheinlich falsche Vorstellung der Molekulargewichtsverteilung. Man kann weiter bemerken: 1die Trennung der Fraktionen ist um so unvollkommener, je höher ihre Viskositätszahl, also ihr Molekulargewicht ist,2es scheint unter unseren experimentellen Bedingungen eine weitere Trennung von Fraktionen nicht mehr möglich zu sein, wenn der noch unfraktionierte Teil des Polymeren, der die höheren Molekulargewichte enthält, eine gewisse Viskositätszahl überschreitet.Die mit der Methode C erhaltenen Verteilungsfunktionen haben weiter bewiesen:3das Hochdruckpolyäthylen hat eine sehr hohe Polymolekularität, die um so größer ist, je höher der mittlere Polymerisationsgrad ist,4die Verteilungskurven scheinen mit der Annahme langer “Schweifungen” auf dem Gebiete der höheren Molekulargewichte in Übereinstimmung zu stehen.

Notes: Es wird die Kinetik der Polymerisation von Vinylmonomeren in wäßriger Lösung beschrieben, die bei Photo-Intiierung durch die Radikale C2O4·- und HCitr·- aus den Ionenpaaren FeC2O4+ und FeHCitr+ erfolgt. Über die spektrophotometrischen Untersuchungen der Formeln und Stabilitäten dieser Eisenoxalat- und Eisencitratkomplexe wie auch über die Ableitung der Gleichgewichtskonstanten für ihre Bildung wird kurz berichtet. Die Absorptionsspektren der Ionenpaare und ähnlicher Komplexe werden angegeben. Die Kinetik der Polymerisationen wurde durch die Abhängigkeit (1) der Monomerenabnahme, (2) der Fe2+-Ionen Produktion und (3) der Kettenlänge des Polymeren von (a) der Konzentration an Monomerem, (b) der Licht-Intensität und (c) der Lichtabsorption der einzelnen Ionenpaare etc. verfolgt. Durch eine kinetische Analyse der experimentellen Ergebnisse wird auf der Grundlage eines Reaktionsschemas geschlossen, daß die Auslösung der Polymerisation durch Radikal-Ionen X·- und der Abbruch durch eine Rekombination erfolgt.

Notes: Bei der Darstellung von Hexahydrotriazinderivaten wurden im Falle des trimeren Methylenanilins, des trimeren Methylen-p-chloranilins und des trimeren Methylen-p-bromanilins je zwei geometrisch isomere Formen isoliert. Umlagerungsbedingungen für die Isomeren werden beschrieben. Von N-alkylierten Hexahydrotriazinen und trimeren Formaldoximderivaten konnten keine isomeren Formen gefunden werden.Durch Umsetzung mit Diphenylketen und Isolierung des resultierenden β-Lactams wurde nachgewiesen, daß bei thermischer Aufspaltung des 1,3,5-Triphenyl-hexahydrotriazins monomeres Methylenanilin entsteht.Makromolekulare Polymerisationsprodukte des Methylenanilins und entsprechende Copolymerisate mit Vinylverbindungen konnten nicht dargestellt werden.

Notes: The second virial coefficient and the intrinsic viscosity in the solution of sodium carboxymethyl cellulose were studied using 2-1 electrolytes as the extraneous salt. It was found that the plots of reduced osmotic pressure vs. concentration are linear for these electrolytes as was observed for sodium chloride and that the second virial coefficient for a given molarity of the added electrolyte decreases in the order of NaCl〉MgCl2〉CaCl2. To interpret this decrease, an osmotic pressure equation for the system 2-1 electrolyte and polymer salt was derived assuming the Donnan equilibrium and an idea of “effective” ionic strength was introduced. On the basis of these results, an osmotic coefficient, which differs from the usual one, was defined and applied to the system so that the observed data were systematically arranged. The result was discussed in terms of the association of gegenions with the polymeric ion.

Notes: L'instabilité du polyacétaldéhyde en solution acide est due à la strdcture polyacétalique de ce polymere. Deux processus succesifs caractérisent cette décomposition; le premier résulte de la rupture hétérolytique de la chaîne polymérique, le second consiste dans la dépolymérisation de l'ion carbonium ainsi formé.La première étape, celle de dégradation, a été suivie viscosimétriquement par la méthode aux viscosimètres réversibles; son mécanisme ionique a été mis en évidence. La vitesse de dépolymérisation est de premier ordre par rapport à la concentration en acide (HOAc); l'énrgie d'activation correspondante s'éléve à 20,4 ± 0,4 Kcal, valeur identique à celle des acétals aliphatiques.La seconde étape, celle de dépolymérisation ionique a été suivie en déterminant la quantité d'acétaldéhyde m i s en liberté; cette détermination a été faite soit par la méthoden au sulfite de sodium, soit polarographiquement. La diminution relative du nombre de liens, c. a. d. la vitesse de formation d'acétaldéhyde, répond à une cosinusoïde en fonction du tentps. Aux dépens des graphiques correspondant à différentes températures, il est possible d'évaluer l'énergie d'activation totale du processus 22,8 Kcal; l'énergie d'activation de dépolymérisation en milieu acide s'éléve à 2,4 Kcal, valeur conforme à la plupart des polymérisations ioniques. En premiere approximation, la vitesse de dépolymérisation acide est également proportionelle à la quantité d'acide dans la solution.Les vitesses de dégradation et de dépolymérisation du polyacétaldéhyde en milieu acide sont beaucoup plus élevées que les vitesses correspondantes en milieu neutre; elles répondent au mécanisme d'hydrolyse par catalyse acide des acétals habituels.

Notes: 1Die beiden Komponenten des Nylons, Hexamethylendiamin und Adipinsäure, Können drei Reihen linearer polymerhomologer Verbindungen bilden: aDiamine (Hexamethylendiamin endständig)bDicarbonsäuren (Adipinsäure endständig)cAminosäuren (Hexamethylendiamin und Adipinsäure endständig) Von den Diaminen und Dicarbonsäuren wurden jeweils die ersten drei Vertreter dargestellt; von den Aminosäuren das Mono-, Di- und Tetramere.2Die röntgenographische Untersuchung der Oligamide ergab, daß schon die kleinsten aus Adipinsäure und Hexamethylendiamin bestehenden Bruchstücke des Nylons dieselben paratropen Röntgenreflexe zeigen wie das Polymere. Aufnahmen in der Kratky-Kammer lieferten Langperiodenreflexe, welche der periodischen Aufeinanderfolge der Moleküle in Richtung ihrer Längsachse entsprechen.

Notes: Für die Konzentrationsabhängigkeit der Sedimentationskonstante einer in Wasser gelösten hochmolekularen Polyvinylpyrrolidon-(PVP)-Fraktion mit der Viskositätszahl Zη25 = 27,5·10-2 [lit/g] gilt abweichend vom üblichen Verhalten von homöopolaren Makromolekülen die empirische Formel: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm s}_{\rm c} = {{{\rm s}_{\rm o} } \mathord{\left/ {\vphantom {{{\rm s}_{\rm o} } 1}} \right. \kern-\nulldelimiterspace} 1} + {\rm K} \cdot {\rm c}^{0,75} $$\end{document}In 0,1 m Phosphatpufferlösung besteht dagegen zwischen der reziproken Sedimentationskonstante und der Konzentration Proportionalität.Die in Wasser beobachtete Abweichung vom normalen Sedimentationsverhalten wird wahrscheinlich durch die polaren Gruppen des PVP-Moleküls bedingt.Der Geltungsbereich der vom Verfasser aufgestellten Formel, die den Zusammenhang zwischen der Viskositätszahl und dem Molekulargewicht wiedergibt, Zη = 1,4 · 10-5 · M0,70 [lit/g], wird durch die an zwei hochmolekularen Fraktionen bestimmten Molekulargewichte und Viskositätszahlen bis zu einem Molekulargewichtsbereich von 3 000 000 erweitert.

Notes: Es wird eine Methode angegeben, die es gestattet, aus der experimentell ermittelten Einstellgeschwindigkeit osmotischer Drucke den Wert für den osmotischen Druck im Gleichgewicht zu berechnen. Vergleichsmessungen mit der statischen Methode ergaben, daß sich aus der Einstellgeschwindigkeit die Steighöhen auf ± 5·10-3 [cm], bezogen auf die statischen Werte, reproduzieren lassen.

Notes: Die in früheren Arbeiten vertretenen Auffassungen zur Struktur chlorierter Polyvinylchloride (PC) werden dargestellt und diskutiert. Unter Berücksichtigung der besonderen sterischen Verhältnisse, wie sie bei Hochpolymeren vorliegen, konnte zunächst festgestellt werden, daß zwischen Polyvinylidenchlorid (rd. 72,6% Cl) und einem hochchlorierten PCU (rd. 73% Cl) kein Unterschied in der Konfiguration solcher Art besteht, wie er von Seipold angegeben wird. Die Annahme eines Schraubenmodells für das Molekül des Polyvinylchlorids ist nicht zwingend, da die röntgenographischen Untersuchungsergebnisse mit einer zweidimensionalen Struktur des Makromoleküls in Einklang stehen.Um Aufschluß über die chemische Struktur der chlorierten Polyvinylchloride zu erhalten, wurden infrarotspektroskopische Untersuchungen durchgeführt. Die Schwingungsspektren der chlorhaltigen Polymerisate wurden ausführlich diskutiert; man kommt zur Annahme struktureller Unterschiede in den Molekülen des Polyvinylidenchlorids und hochchlorierten PCU. Die Verteilung der Chloratome in den Makromolekülen konnte durch eine quantitative Infrarotanalyse der Methylengruppen aufgeklärt werden. Es wurde bewiesen, daß das Beersche Gesetz für diese Bestimmung näherungsweise gültig ist. Die Untersuchung führte zu der Annahme, daß bei der Nachchlorierung des PCU die 1,2-Chlorierung bevorzugt ist und in einem hochchlorierten Polyvinylchlorid nur noch etwa 25% der ursprünglich im PCU vorhandenen Methylengruppen vorliegen.Es konnte gezeigt werden, daß unter bestimmten Versuchsbedingungen eine Überchlorierung des PCU erfolgt. Bei Anwendung von Thionylchlorid als Lösungsmittel wurde bei der Chlorierung unter Belichtung ein PC mit 75,6% Cl erhalten, so daß die Annahme einer besonderen Struktursymmetrie für das hochchlorierte PCU zur Erklärung des charakteristischen zeitlichen Ablaufs der Chlorierung nicht notwendig ist.Chemische Umsetzungen des chlorierten Polyvinylchlorids mit Stickstoffbasen ließen erkennen, daß die Reaktion des PC mit Anilin nicht als Strukturkriterium benutzt werden kann, wie das in früheren Arbeiten der Fall war. Es wurde außerdem festgestellt, daß Stickstoffbasen die intramolekulare Chlorwasserstoffabspaltung aus den chlorhaltigen Polymerisaten begünstigen, was im Hinblick auf den im weiteren Verlauf der Arbeit diskutierten Reaktionsmechanismus der Chlorierung von Bedeutung schien.Die Reaktion von Davis und Heggie mit Kaliumjodid zum Nachweis von 1,2-Dihalogeniden wurde an einem PC untersucht und im Zusammenhang mit dem vorliegenden Strukturproblem diskutiert.Eine kinetische Betrachtung der Chlorierung des PCU fiihrte zu der Annahme, daß es sich hierbei vorzugsweise um eine additive Chlorierung handelt, bei der die Chloratome zwangslaufig in 1,2-Position treten.

Notes: Nach verschiedenen Verfahren hergestellte Polyvinylchloride wurden fraktioniert und die Fraktionen der partiellen und vollständigen Reduktion mit Lithiumaluminiumhydrid unterworfen. Bei der vollständigen Reduktion unter Reinstickstoff wurde ein Paraffin vom E. P. 118°C erhalten. Bei der partiellen Reduktion wurden unter Stickstoff polymeranaloge Produkte erhalten, in Gegenwart von Sauerstoff erfolgt ein Abbau. In den abgebauten Produkten konnten Hydroxylgruppen nachgewiesen werden. Eine Möglichkeit der Deutung dieses Befunds wird erörtert. Für alle untersuchten Fraktionen verschiedener Polyvinylchloridtypen wurde die gleiche Viskositäts-Molekulargewichtsbeziehung erhalten.

Notes: Es wird die Darstellung von 3 Ätherdialdehyden aus p-Oxybenzaldehydkalium und verschiedenen ω,ω′-Dihalogenverbindungen und deren Umsetzungen mit γ,γ′-Diaminodipropyläther beschrieben. Der Übergang der kristallinen, dimeren, cyclischen, 54-gliedrigen Schiffschen Base aus Hexamethylenglykol-bis-(4-formylphenyläther) und γ,γ′-Diaminodipropyläther in eine faserige, polymere, instabile Schiffsche Base wurde durch Überführung der letzteren in stabile Derivate und durch vergleichende Viskositätsmessungen bewiesen.

Notes: Es wurden Mischkondensate verschiedener Zusammensetzung von Adipinsäure-Hexamethylendiamin und ∊-Caprolactam hergestellt und in Fraktionen zerlegt. Die molekulare Vertilung wird durch die Kondensationsbedingungen beeinflußt. Durch Bestimmung des osmotischen Druckes und der Viskositätszahl wurde eine Viskositätszahl-Molekular-gewichts-Beziehung ermittelt. Die gefundene Funktion \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Z}\eta {\rm = 1,06} \cdot 10^{- 4} \overline {\rm M} ^{0.71} $$\end{document} gilt für alle untersuchten Mischkondensate unabhängig von der Zusammensetzung. Der Schmelzpunkt eines Kondensates wird mit zunehmendem Molekulargewicht höher, bleibt dann aber von einem bestimmten Molekulargewicht an konstant. Ab einem bestimmten Molekulargewicht tritt Faserbildung ein. Der Schmelzpunkt, die Steigungskonstante B des osmotischen Druckes, die durch Fällbarkeit ausgedrückte Löslichkeit und die Höhe der Mindestmolekulargewichte für die Faserbildung bzw. die Schmelzpunktskonstanz sind abhängig von der Zusammensetzung der Kondensate.

Notes: The ionic and photochemical chlorinations of methyl- and ethylpolyacrylates and of polymethylmethacrylate have been studied. The position of the halogen was determined by the method with aniline, on account of the differences of the rate of reaction of these atoms in function of their position with respect to the ester function.The ionic chlorination of polyacrylic esters, carried out at 100° C in the presence of iodine as a catalyst, orients the first chlorine atom in α position. The next halogen is likely directed into the ester function. Polymethylmethacrylate is unsensitive to the ionic chlorination.The photochemical chlorination, carried out in carbon tetrachloride solution under U. V. illumination, directs the halogen statistically. In the case of polymethylmethacrylate, at a degree of substitution of 1 (DS= 1), 3/5th of the chlorine are present in the side methylgroups; at DS = 2 the structure of the polymer is In these polymethacrylic derivatives the steric hindrances are very important and the chain—CHCl— groups are not attacked by the aniline; the side chloromethylenic functions —CH2Cl alone are substituted by this reagent. In the case of polyacrylic esters the ratio halogen α to halogen β is 1/2 at a DS of ≤1. At higher DS values, a appreciable chlorination affects the ester group.From viscometric point of view, the degradation during the photochlorination is much more pronounced in the case of polymethylmethacrylate than for the polyacrylic derivatives; it is also a function of the concentration of the chlorine in the reaction medium. Contrarily during the ionic chlorination of polyacrylic esters no degradation occurs.

Notes: Die Molekulargewichtsverteilungskurve von Polyvinylpyrrolidon (PVP) wird durch fraktionierte Fällung unter Benutzung verschiedener Lösungsmittel und Fällungsmittel bestimmt.Zur Beurteilung der Güte einer Fraktionierung wird die Uneinheitlichkeit des Produktes aus dem Gewichtsmittel und dem Zahlenmittel des Molekulargewichts berechnet. Die Güte einer Fraktionierung wird vor allem vom durchschnittlichen Volumenverhältnis und im geringeren Maße vom verwendeten Lösungs- und Fällungsmittel bestimmt.Bei gleicher PVP-Konzentration der Ausgangslösung wird beim System Wasser/Aceton und beim System Alkohol/Petroläther die beste Fraktionierung erzielt.Die Molekulargewichtsverteilung von PVP-Fraktionen der Wasser/Aceton- und der Chloroform/Petroläther-Fraktionierung wird durch Trübungstitration ermittelt und mit den nach G. V. SCHULZ berechneten Molekulargewichtsverteilungskurven verglichen. Zwischen beiden Kurven besteht gute Übereinstimmung, wenn man zur Berechnung für das Trennungsverhältnis ϑ die Gleichung zugrunde legt: \documentclass{article}\pagestyle{empty}\begin{document}$$ \vartheta = \frac{1}{\varphi } \cdot {\rm e}^{{\rm P}^{\rm n} \cdot {\rm \varepsilon }}$$\end{document}(ϕ= Volumenverhältnis, P= Polymerisationsgrad, ε= Energiefaktor, n= Exponent).Ein Vergleich zwischen den experimentell bestimmten und den berechneten Verteilungskurven zeigt, daß der Fraktionierungseffekt abhängig ist vom Volumenverhältnis ϕ und der Größe des Exponenten n. Dieser wird vom verwendeten Lösungs- und Fällungsmittel bestimmt. Für den Exponenten n ergibt sich für die Wasser/Aceton-Fraktionierung ein Wert von 0,8 und für die Chloroform/Petroläther-Fraktionierung ein Wert von 0,55.Für die differentiellen Molekulargewichtsverteilungskurven der Fraktionen ergeben sich beim PVP bei allen Fraktionierungen unsymmetrische Gauss sche Kurven. Die integralen Massenverteilungskurven dieser Fraktionen ergeben im Wahrscheinlichkeitsnetz mit logarithmischer X-Achse annähernd gerade Linien.Die Uneinheitlichkeit der Fraktionen läßt sich näherungsweise als Funktion des Quotienten cr/n·log ϕ darstellen (cr = relative PVP-Konzentration). Die Uneinheitlichkeit der Anfangsfraktionen erweist sich beim PVP vor allem bei relativ einheitlichen Präparaten größer als die des Ausgangsproduktes.

Notes: The viscosities of a number of γ-globulins from various sources were studied. It was found that the dependence of the reduced specific viscosity on concentration of the globulins is a linear function. The slopes of the regression lines were positive, and they varied in the range of 0.0015-0.017. The intrinsic viscosity values of the native γ-globulins varied in the range of 0.048-0.083 (at ionic strength 0.1 and PH 5,8-7,7). The viscosity of various γ-pseudoglobulin samples was found to be generally the same as the viscosity of the whole γ-globulin fraction. The results also showed that the viscosity differences between various preparations are due partially to artifact formation (aggregation) during isolation. The possibility of individual shape and other differences, however, is not excluded. The flow properties of the γ-globulins which were denatured by guanidine thiocyanate and by Aerosol OT also were studied.

Notes: Die Konzentrationsabhängigkeit der Viskosität von Lösungen unverzweigter Fadenmoleküle gehorcht im idealen Lösungsmittel einem Gesetz von Arrhenius: lnηr = [η]0·c. In anderen Lösungsmitteln treten Abweichungen \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{\ln }}{{\rm c}} - [{\rm \eta ]}_{\rm 0}$\end{document} auf, die mit wachsendem lnηr exponentiell abnehmen. Ihre Größe, ausgedrückt durch das Verhältnis der Viskositätszahlen [η]0 und [η] bestimmt allein den Zahlenwert der Huggins-Konstante bzw. der um 0,5 negativeren Arrhenius-Konstante K1. Diese Beziehung wird graphisch angegeben.Mit Hilfe von K1 und [η] kann man die für das Polymere charakteristische Viskositätszahl [η]0 ermitteln. Die Bestimmung der Viskositätszahl [η] aus einer Messung bei einer Konzentration wird diskutiert und eine bis ηr ≍ 106 in guten Lösungsmitteln geltende Gleichung für die Konzentrationsabhängigkeit der Viskosität mitgeteilt.

Notes: Dans le but de déterminer la portée pratique de l'étude de la lumière diffusée par des particules soumises à un champ d'orientation, nous avons établi les équations permettant de relier la variation de l'intensité diffusée aux caractéristiques moléculaires en fonction du champ d'orientation. Nous donnons tout d'abord les premiers termes du développement en série de ces équations dans le cas où la forme des particules et la nature du champ d'orientation sont quelconques. Puis, nous donnons l'expression complète de la fonction de répartition de l'intensité lumineuse dans le cas où le champ d'orientation est un champ électrique et où les molécules sont assimilables à des pelotes de Gauss. Les résultats de cette analyse théorique suggèrent une méthode expérimentale simple qui permet de caractériser la rigidité des molécules. Après une brève description de l'appareillage utilisé, nous citons, comme exemple d'applications, les expériences faites sur un échantillon de poly-DL-phénylalanine. En solution dans le benzène ces molécules se comportent comme des chaǐnes de Gauss flexibles. A partir des résultats expérimentaux il est possible de calculer, entre autres grandeurs physiques, la valeur du moment électrique porté par ses chaǐnons. Du point de vue pratique, le choix d'un champ électrique limite les applications aux molécules en chaǐnes porteuses d'un moment électrique. Cette restriction tomberait si l'on remplaçait le champ électrique par un champ hydrodynamique.

Notes: Les propriétés diélectriques et les facteurs de perte ont été mesurés pour des solutions diluées de chlorure de polyvinyle dans le tétrahydrofurane et des mélanges de ce solvant avec l'heptane, pour des solutions de polyméthacrylate de méthyle dans le benzène et le toluène, et pour des solutions d'acétate de polyvinyle dans le toluène. Les concentrations variaient de 0.5 à 8 g./100 ml. Les fréquences allaient de 0.01 à 35 mégacycles/sec. et les température de -35° à +25°C. Un seul échantillon de chlorure de polyvinyle a été utilisé (DP = 1750); par contre quatre fractions de polyméthacrylate de méthyle (DP = 240-12.500) et quatre d'acétate de polyvinyle (DP = 2.550-23.250) ont été utilisées. Les valeurs numériques des trois polymères étaient plutǒt similaires. Les moments dipolaires moyens étaient proportionnels à la carrée du DP. Les temps de rélaxation étaient pratiquement indépendants du DP.

Notes: The vaper pressure of ethyl acetate-natural rubber mixtures has been studied at 25 and 50°C. over the whole range of miscibility. Current statistical theories of polymer solutions fail to account quantitatively for the observed entropy of mixing; the discrepancy is attributed to the occurrence in this system of non-random mixing.

Notes: Osmotic pressure, initial phase separation, and viscosity results are presented for dilute solutions of cellulose nitrate, cellulose acetate, and ethyl cellulose, using polymers of similar molecular weight and degree of substitution. A fairly wide range of solvents has been used in each case. Osmotic pressure results suggest molecular dispersion of polymer in most solvents but there is evidence for association of ethyl cellulose in aromatic hydrocarbons. Values of the Huggins μ are obtained and, for systems involving cellulose nitrate and ethyl cellulose in homologous series of ketones and acetates, seem to fall to a minimum and then increase on ascent of each series. It is suggested that the heat term in μ should include an exothermic contribution arising from solvation in addition to an endothermic contribution resulting from mixing of solvated polymer and solvent. It is tentatively suggested that, in a homologous series of solvents, the entropy and exothermic contributions may not vary much and that the variation of μ may arise from varying endothermic contributions. The volumes of hexane required to cause initial phase separation of the nitrate and acetate from solution increase with solvent power, as estimated from μ, but with ethyl cellulose the volumes tend to decrease. It is suggested that solvated polymer may separate from solutions involving polar solvents and, making certain assumptions, estimates are made of the solubility parameters of the polymers separating. Those for cellulose nitrate vary markedly with solvent. The variation of solubility parameter with solvent is less with cellulose acetate and ethyl cellulose but in the latter case values for polymer separating from polar solvents are less than from nonpolar. Comparison of these estimated solubility parameters with those of the solvents and hexane suggests that the volumes of hexane required to cause initial phase separation will only serve as measures of solvent power if the solubility parameters of solvents and precipitant all lie on the same side of that of the polymer separating. This seems to be so for cellulose acetate and possibly the nitrate but not for ethyl cellulose. Comparison of viscosity parameters and values of μ suggests that in certain cases both [η] and the initial slope of the plot of ηsp/c against c increase with solvent power. Other suggested viscosity measures of solvent power do not seem to be generally applicable. Some variation of chain configuration with solvent seems probable. Solvation, solvent type and association of polymer may also affect the viscosities of dilute solutions of cellulose derivatives.

Notes: Solutions of polyisobutylene in tetralin were observed to show antithixotropy. Quantitative results are given, and comparison is made with a non-Newtonian liquid of constant viscosity and with one which shows (positive) thixotropy.

Notes: On effectue sur deux types de polymères des expériences de biréfringence d'écoulement analogues à celles de Cerf, c'est-à-dire que l'on mesure la pente tg α de la tangente à l'origine de la courbe d'extinction dans des solvants de viscosité η0 variable. (a) Polystyrènes. Les mesures portent sur quatre échantillons de masses 520.000, 1.240.000, 3.530.000 et 10.000.000. Pour chacun d'eux, à une concentration c donnée, tg α est une fonction linéaire de η0. Les droites relatives à diverses concentrations ont měme ordonnée à l'origine B. La quantité B est proportionelle à la masse moléculaire. Ces résultats faciliteront les extrapolations à c = 0 et à η0 = 0 des mesures d'angle d'extinction. (b) Acides désoxyribonucléïques. Les valeurs de tg α obtenues sur un échantillon de masse 6 × 106 se placent au voisinage de deux droites d'ordonnées à l'origine respectivement nulle et positive et dont les pentes sont dans un rapport de l'ordre de 4,5. Des observations analogues sont faites sur les résultats obtenus par d'autres auteurs, à l'aide d'un échantillon de měme masse, préparé par une méthode différente. On effectue une premiére confrontation entre les résultats expérimentaux et une théorie récente, fondée sur le modèle à N sous-chaǐnes de Gauss et qui tient compte de la viscosité interne de la particule. Une interprétation plus complète nécessitera la connaissance des valeurs de la viscosité intrinsèque des polymères étudiés dans les différents solvants utilisés. D'ores et déjà on peut dire que la plupart des données expérimentales sont en accord avec les conclusions théoriques. En particulier, on confirme la possibilité de déterminer le terme de viscosité interne comme ordonnée à l'roigine de l'asymptote à la courbe tg α en fonction de η0. On corrobore les conclusions de Sadron quant à l'existence de deux catégories d'acides désoxyribonucléïques, les deux échantillons examinés ici présentant une rigidité différente. Toutefois, les variations du terme de viscosité interne avec la masse moléculaire paraissent difficilement compatibles avec la théorie.

Notes: The dielectric properties of polymer solutions are calculated on the assumption that each polymer molecule may be divided in N submolecules whose end-to-end distance shows Gaussian distribution. Electrical charges of alternating sign are attributed to the ends of these submolecules. The equations of motion are given for free-drained structures. From these equations of motion the diffusion equation in configuration space is constructed. The average dipole moment can be calculated by a simple integration procedure. It is found that there should be two dispersion regions, one at low frequencies proportional to 1/N2 and one at high frequencies independent of N. The high frequency maximum in the loss curve has a shape which is very nearly that for a process with a single relaxation time.

Notes: Les auteurs ont mesuré les moments électriques des polyoxyéthylèneglycols et des polyoxyéthylèneglycols diéthoxylés de degré de polymérisation compris entre 2 et 230. Ils ont calculé, en tenant compte des interactions, les valeurs théoriques correspondantes qui sont en accord avec les résultats expérimentaux. Ils montrent ensuite que le carré moyen du moment électrique \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\mu ^2 } $\end{document} est, dans les cas usuels, proportionnel au degré de polymérisation, ce qui signifie que l'“effet de volume” n'a pas d'influence sur la grandeur de \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\mu ^2 } $\end{document}. Ils en déduisent une méthode de mesure des interactions à courte distance dans un solvant quelconque. L'étude du polyméthacrylate de méthyle montre que ces interactions sont indépendantes du solvant et de la température, aux erreurs d'expérience près.

Notes: The mean square length and mean square radius of gyration of 1,4′-polysaccharides and of cis- and trans-polybutadiene were calculated by an extension of the method of Eyring and Benoit, the results being expressed in terms of the degree of polymerization and of certain parameters of physical significance connected with the rotations about the various single bonds in these molecules. The calculations were based on the simplifying assumptions that no correlation exists between rotations about bonds separated by at least one pyranose ring or double bond and that the polysaccharide molecules are made up of pyranose rings in the “chair” form. The excluded volume effect was neglected throughout. The results obtained show that, if the mean square length is plotted against the degree of polymerization, n, then the deviations for small n from the limiting straight line obtained for larger n will have the form of a damped vibration, n appearing instead of the time. In certain cases, however, the results for odd and even n fall on different curves.

Notes: The osmotic coefficient and the activity coefficient of polyelectrolyte solutions were calculated by applying the relation of the chemical equilibrium between counterions retained in the apparent volume of polyelectrolyte molecules and those free from molecules. The relation of these coefficients to the concentration of polyelectrolytes depends on the shape of molecules and thus the qualitative difference observed in the behavior of the coefficients of different polyelectrolytes can be explained. The effect of valencies of ions was studied. In a mixture of counterions, all ions of the larger valency are bound by polyelectrolyte molecules when the density of ionized groups on molecules is larger than a certain value determined by the mixing ratio of counterions. The swelling force of polyelectrolyte gels was obtained by a similar method. A new formula is presented in which the osmotic force of counterions retained by chains plays an important role. the anisotropy of the swelling force of gels with oriented chains is attributable to the anisotropy of this osmotic force.

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

Notes: Les amidons de plantes différentes et de leurs fractions donnent après leur dissolution et leur dessication des images très diverses dans le microscope électronique. Elles se différencient aussi dans leur spectre infrarouge et surtout dans le domaine d'absorption qui correspond aux groupes d'atomes qui contiennent de l'oxygène. Dans ce domaine d'absorption, les processus de vieillissement deviennent perceptibles eux aussi. Les spectres infrarouges des films d'amidons désséchés laissent conclure à des liaisons d'hydrogène très importantes. Des phénomènes de vieillissement peuvent s'observer également à l'aide du spectre ultra-violet, surtout dans un milieu alcalin.