ALBERT

Notes: A theory for the infrared dichroism of a crosslinked, rubber-like amorphous polymer is described. The dichroism of a typical rubber is estimated to be measurable. The dichroism-stress ratio is independent of strain and degree of crosslinking and serves as a measure of the number of monomer units per statistical segment, an index of chain stiffness.

Notes: Vinylpyridine was polymerized in suspension, using azobis-iso-butyronitrile as initiator. The polymer was fractionated by partial precipitation from methanol solutions by addition of toluene to cloud point in chilled solution and then raising the temperature. Viscosities of four fractions were determined at 25, 50, and 70° in absolute ethanol. Rayleigh ratios and scattering asymmetry were determined for eight fractions; from the corresponding Zimm plots, molecular weights, coil diameters, and virial coefficients were determined. Addition of ammonia was found necessary at low concentrations to suppress ionization due to traces of acid impurities. Addition of water (a nonsolvent) lowers the second virial coefficient. Molecular weights were determined for two fractions by osmotic pressure. In absolute ethanol, the results are summarized by the equation [η] = 2.5 × 10-4M0.68; experimental range 0.102 ≤ 106 M ≤ 1.85. The second virial coefficient from light scattering was 4.2 ± 0.3 × 10-4, independent of molecular weight; the osmotic values agreed within experimental error. The Flory constant was found to be 2.1 ± 0.3 × 1021. Extrapolation for the θ-point leads to the rough estimate θ ≈ -50°C. Evidence is presented which shows that polyvinylpyridine degrades slowly in solution.

Notes: Study of the diffusion in polymers of molecules comparable in size and structure to the segments of the chain molecules is suggested as a means of securing information on structure and molecular friction forces in polymers. A convenient method for measuring the diffusivity in polymers of such compounds tagged with C-14 was devised and used to study the diffusivity of octadecane, octadecanol, stearic acid, and octadecyl stearate for a range of temperatures in polymers including natural rubber, GR-S, polybutadiene, polyisoprene, and polyisobutylene. Diffusivities were independent of concentration for the range used. The diffusivities of straight chain hydrocarbons in natural rubber appear to vary inversely as the molecular weight of the diffusing compound. Evidence was found for association effects in the diffusion of stearic acid in natural rubber. Activation energies for diffusion of the compounds were quite similar in any one polymer and of the same order as reported for low molecular weight hydrocarbons and for viscous flow. Larger differences in activation energies were observed for diffusion in the different polymers. Correlations were observed for the diffusivities of octadecane in a series of polymers with their densities and thermal expansivities, especially the latter. Some study was given to the effect on the diffusivity of octadecane of such parameters as polymer unsaturation, solution viscosity, molecular weight, and crosslink density. The diffusivity of octadecane in natural rubber had a pronounced maximum as a function of crosslink density, coinciding with the maximum in tensile strength. Possible implications of this are discussed. The diffusivities of octadecane in a series of elastomers were studied in relation to the internal frictional losses observed for 60 cps vibrations over a range of temperatures. It was concluded that frictional forces deduced from the diffusivity measurements have some correspondence to high frequency viscoelastic phenomena which involve small units of structure comparable in size to the segments of the polymer molecules.

Notes: The polymerization reactions of trans-cinnamoylferrocene have been described and a number of copolymers have been characterized. trans-Cinnamoylferrocene does not homopolymerize using conventional free radical techniques but forms copolymers with styrene, acrylonitrile, methyl methacrylate, ethyl acrylate, butadiene, isoprene, and 1,1-dihydroperfluorobutyl acrylate.

Notes: On exposure to Co-60 γ-radiation, mixtures of natural rubber and methyl methacrylate yield almost exclusively rubber-polymethyl methacrylate graft polymers. An appreciable amount of free polymethyl methacrylate is formed only in the presence of a transfer agent or following radiation-induced degradation of the interpolymer. Structural characterization of the products has been made. The findings are not consistent with random grafting of the synthetic polymer on linear rubber molecules of random molecular size distribution - the rubber component appears to comprise several crosslinked molecules. The influence of the purity of the rubber, monomer concentration, field intensity, the presence of transfer agent, and the gel effect on the rate of formation, yield, and structure of the interpolymer are reported.

Notes: Branching frequencies have been determined by dilute solution measurements through evaluation of the radius of gyration, either directly by light scattering or indirectly through the intrinsic viscosity. A third possibility is presented by the decrease in the second virial coefficient, A2, with branching. Through use of a semi-empirical relation between A2 and [η], it is shown that a reasonable approximation over a wide range of branching frequencies should be furnished by: \documentclass{article}\pagestyle{empty}\begin{document}$ h^3 = {{\left[ \eta \right]_\theta ^* } \mathord{\left/ {\vphantom {{\left[ \eta \right]_\theta ^* } {\left[ \eta \right]_\theta }}} \right. \kern-\nulldelimiterspace} {\left[ \eta \right]_\theta }} \cong {{A_2^* } \mathord{\left/ {\vphantom {{A_2^* } {A_2 }}} \right. \kern-\nulldelimiterspace} {A_2 }} $\end{document} where the quantities designated by an asterisk refer to the branched polymer, and the corresponding unmarked quantities to a linear polymer having the same molecular weight. The validity of the approximate relation between A2 and branching is confirmed using the data of Thurmond and Zimm for linear and branched polystyrene, and using data for linear and branched polyethylene presented here. This procedure should prove useful inasmuch as the molecular weight of a branched polymer must be determined by an absolute method, and the branching frequency can be estimated through the A2*/A2 ratio from these same data.

Notes: The low and atmospheric pressure polymerizations of ethylene using catalysts prepared from n-butyl lithium or isoamyl lithium and titanium tetrachloride were studied. The efficiency of the catalyst depended on the molecular ratio of the alkyl lithium to titanium tetrachloride. Optimum molecular ratio for the n-butyl lithium-titanium tetrachloride was found to be between 2.15-2.47 with a sharp drop between 2.15-1.49; for the isoamyl lithium the optimum was between 2.5-4.3. Within the examined interval (of atmospheric pressure to a pressure of 60-70 lb./sq. in.) higher pressure caused an increase in the yield of polyethylene. No pronounced effect in polymerization was found in the temperature interval of -10-55°. The catalyst is stable for a few days if kept refrigerated. Petroleum ether, b.p. 40-80°, was the best solvent both for the preparation of the catalyst and for the polymerization. Ligroin, toluene, and especially ether interfered with the polymerization. The polyethylenes obtained melted between 125-135°.

Notes: Electron micrographs of highly crystalline PTFE crystallized by slow cooling from temperatures not far above the melting point show well-marked bands, often with striations perpendicular to the bands; optical evidence shows that the chain molecules are parallel to the striations. The structure is in marked contrast to the spherulitic structure of most polymers; it appears that in PTFE the molecules are straight and parallel for much greater distances than in other polymers, and it is suggested that the width of the bands is a measure of molecular length. The unusual structure is attributed to the unusual stiffness of the fluorocarbon chain; the molecules in the liquid are straighter and less tangled than in other polymer melts. Heating to 500°C., followed by slow cooling, gives a modified structure approaching the spherulitic type found in other polymers; it is suggested that this is due to increased molecular tangling in the melt at higher temperatures. One type of polymer shows bands of remarkably uniform thickness, suggesting unexpected uniformity of molecular length. PTFE wax made by thermal or radiation degradation of the high polymer shows well-defined spiral growth steps due to dislocations; the step heights suggest an unexpected uniformity of molecular length.

Notes: Stress relaxation in the systems PVAc (polyvinyl acetate)-water, PVAc-methanol, PMA (polymethyl acrylate)-water, and PMA-methanol was measured at several temperatures above the glass-transition points of the pure polymers in ranges of sufficiently low concentrations of diluents. It was found that the time-concentration superposition principle as proposed by Ferry is applied successfully to these data to obtain master relaxation curves of the pure polymers at fixed temperatures. The master relaxation curves so obtained at different temperatures were further superposed with each other by horizontal shift along the log time axis, in agreement with the time-temperature superposition principle. The concentration shift factor ac as a function of diluent concentration C at fixed temperature was well interpreted in terms of the modified Doolittle's free volume equation for the viscosity of supercooled systems on the assumption that the fractional free volume of the system increases linearly with C. The proportionality coefficient, β, of this linear relation provides a measure of the plasticizing effect of a given diluent on a given polymer. It was found that β is practically independent of temperature at sufficiently small C and is larger for water than for methanol in both polymers studied. On the basis of Doolittle's viscosity equation modified to account for the concentration effect, it is shown that the glass-transition temperature Tg of a given polymer-diluent pair decreases with C in a linear fashion in the range of small C. The value of β can also be calculated from the slope of this linear relation. Values of β determined in terms of this procedure from literature data on a variety of polymer-diluent pairs are given in a tabular form. For a given polymer the β values generally become smaller as the size of diluent molecule is increased, but no unique relation can be obtained between the two quantities. Equilibrium sorption and integral sorption processes were studied on the four pairs of polymer and diluent mentioned above, not only to obtain data needed for analyzing the present stress-relaxation data but also to find information which will serve a study described in Part III of this series which is concerned with diffusion-controlled stress-relaxation in amorphous linear polymers. Some correlation (though not definite) appears to exist between the diffusion coefficient D (at zero concentration) and the plasticizing parameter β for a given polymer. This may be expected because both D and β are quantities depending on the frequency at which polymer segments jump cooperatively in the presence of a low molecular weight diluent.

Notes: The subject is of importance in a variety of colloidal and biological problems. It includes (a) adsorption on solid surfaces, (b) the equation of state of mono or multilayers on liquid interfaces, (c) surface tension of solutions. There are two aspects, namely the molecular configurations at the interface and the resulting contributions to the free energy. Assume the surface to be a regular array of adsorbing sites, each accommodating one chain segment. Unless the segment-site interaction is extremely large in comparison with kT and of long range, flexible chains will not deposit completely. H. L. Frisch and the author have previously shown for random coils that the average number v of segments adsorbed out of a total of t per chain is proportional to t1/2 and increases with chain flexibility and thus temperature in a good solvent. They also established the consequences of this for (a) and (b). The present discussion, based on work in collaboration with Frisch, includes surface tension and differs from our earlier results at low surface concentration θ. As previously, the treatment neglects fluctuations in v, which are small for large t. The isotherm in dilute solutions is essentially θ/[v(1 - θ)v] = Kc, where K is a function of v, T, depending on the properties of the bulk polymer and solvent and increasing with molecular weight. Deviations from a Langmuir isotherm are less pronounced than for rigid molecules. The second virial coefficient of the pressurearea curve depends on the ratio v/t and hence on molecular weight and flexibility differently from a completely deposited molecule, flexible or rigid. The limiting change in surface tension depends on two-opposing terms. When adsorption is sufficiently strong, a decrease proportional to K, and hence increasing with molecular weight, results. This competes with an increase proportional to v/t ∝ t-1/2, arising from the activity of the solvent.

Notes: Heats and entropies of dilution of dilute solutions (concentration range 0.2-1.0 g./100 ml.) of cellulose acetate, ethyl cellulose, and cellulose nitrate, of similar degrees of substitution and polymerization, in a number of representative solvents, have been obtained from temperature coefficients of osmotic pressure. In some cases, degradation of polymer at the higher temperature used seems possible and an attempt is made to allow for this in the estimation of values of ΔH̄1 and ΔS̄1. Heats of dilution for the cellulose acetate and ethyl cellulose systems are generally endothermal, those for the cellulose nitrate systems being exothermal. Entropies of dilution are less than those obtained for comparable systems containing less polar and more flexible polymers. Those for the cellulose nitrate systems do not differ much from “ideal” values. The value of ΔH̄1/φ22, where φ2 is the volume fraction of polymer calculated from the density of the bare polymer, for each cellulose acetate system and most of the ethyl cellulose systems seems to be effectively independent of concentration. Values for the cellulose nitrate systems seems to be effectively independent of concentration. Values for the cellulose nitrate systems become less negative as the concentration increases. Values of ΔH̄1 for the cellulose acetate and ethyl cellulose systems are generally in the order to be expected from the solubility parameters of the solvents and polymers. ΔS̄1/φ22 may vary with concentration in a manner rather similar to that suggested by simpler lattice theories. These results are tentatively interpreted in terms of solvation of polymer and possible endothermal mixing of solvated polymer and solvent. Although values of the entropy contribution to the interaction parameter χ1 for the cellulose acetate and ethyl cellulose systems are not always inagreement with the predictions of simpler lattice theories it is possible, if solvation, segment size, and chain stiffness are allowed for, that the thermodynamic properties of dilute solutions of cellulose derivatives may be at least qualitatively interpreted in terms of such theories.

Notes: L'influence de la concentration sur la biréfringence d'écoulement des solutions de desoxyribonucléate de sodium est étudiée pour divers échantillons d'ADN. Lors du gonflement dans NaCl molaire du gel d'ADN obtenu par précipitation alcoolique, l'ADN se dissout progressivement. Des prélèvements successifs permettent de séparer des fractions qui diffèrent par leurs propriétés en solution diluée. Certaines fractions, principalement celles d'extraction précoce, présentent, aux très faibles concentrations, des anomalies de biréfringence d'écoulement. C'est ainsi qu'à gradient de vitesse constant l'angle d'extinction χ et le facteur optique ψ augmcntent de façon anormalement rapide avec la dilution dès que la concentration devient inférieure à 2 × 10-5 g/ml. Dans les conditions de l'expérience, les particules d'ADN sont pratiquement indéformables; les variations de χ et de ψ. semblent donc indiquer, aux grandes dilutions, une importante diminution de la taille des particiilrs et une augmentation de leur anisotropie. Au contraire, avec les fractions d'extraction tardive, l'augmentation d'anisotropie est souvent accompagnée d'un accroissement apparent de taille. Par contre, avec les mêmes échantillons d'ADN et dnns le même domaine de concentration, la visrosimétric et l'ultracentrifugation ne mettent pas d'anomalir en évidence, d'où une apparente contradiction. La question est discutée tie savoir si les effets observés en biréfringence d'écoulement peuvent être ou non imputés à des intcractions entre les molécules dissoutes. On recherche aussi quel modèle de particule peut être simultanénent compatible avec les résultats de la biréfringence d'écodement, de la viscosité et de la sédimentation, compte tenu des données récentes sur la structure de l'ADN. Certaincs contradictions semblant difficilement réductibles, on est conduit à suggerer l'éventuelle nécessité de reconsiderér la signification physique des grandeurs mesurées et des divers paramètres utilisés pour caractériser les particules de polyelectrolytes macromoléculaires en solutions très diluées.

Notes: Die an 15 Polyvinylacetat-Fraktionen in Butanon bei 25°C. durch Lichtstreuungs-, Sedimentations-, Diffusions-, Osmose und Viskositäts-Messungen gefundenen Beziehungen (1)\documentclass{article}\pagestyle{empty}\begin{document}$$ [\eta ] = 4.20 \times 10^{ - 2} \bar M_{w,sD^{0,62} } [{\rm cm}.^3 {\rm g}.^{ - 1} ] $$\end{document} (2)\documentclass{article}\pagestyle{empty}\begin{document}$$ \overline {h_{w^2 } } = k \bar M_w [A^2 ];k = 1[A^{ - 2} ] $$\end{document}(h = Fadenendenabstand) werden anhand der hydrodynamischen Theorien von Kirkwood-Riseman, Kuhn-Kuhn, Debye-Bueche, Peterlin und Fox-Flory diskutiert. Die experimentell bestimmten Fadenenden-Abstände stimmen mit den aus Viskosität und Molekulargewicht nach den Theorien von Kuhn-Kuhn, Peterlin und Fox-Flory ausgezeichnet, nach Kirkwood-Riseman noch innerhalb 10% überein, bei den nach Debye-Bueche berechneten traten grössere Abweichungen auf. Die aus Sedimentation und Diffusion nach Kuhn-Kuhn berechneten Fadenenden-Abstände decken sich mit den experimentell aus Streulicht-Messungen gefundenen, bei allen anderen Theorien treten mehr oder minder starke Abweichungen auf. Die gleichzeitige Gültigkeit von (1) und (2) wird durch einen mit dem Molekulargewicht abnehmenden hydrodynamischen Radius gedeutet. Die Unstimmigkeiten bei den einzelnen Theorien werden im Lichte dieser Anschauung diskutiert.

Notes: The use of isotopically labelled reagents has contributed significantly to study of many of the processes in radical polymerizations; one of the most useful applications concerns the detailed mechanisms of initiation processes in sensitized polymerizations. Work with a typical azo initiator is reviewed. Recent studies with 14C-benzoyl peroxide are discussed in more detail. It is shown that it is possible to determine accurately the rates of initiation processes involving benzoyloxy and phenyl radicals. It is also possible to determine the relative reactivities of unsaturated compounds towards the benzoyloxy radical. A description is given of some preliminary studies of N-nitrosoacetanilide as a source of free radicals.

Notes: Les masses moléculaires et les rayons de giration moyens mesurés par diffusion de la lumière sur les solutions de polyéthylène “haute pression” ne paraissent pas dépendre, d'une manière notable, de la température des mesures ou de la nature du solvant utilisé. Leur valeur élevée est due à la présence, dans la solution de particules non dissociables (microgel) engendrées par l'intervention combinée des réactions de transfert intermoléculaire et des réactions de terminaison mutuelle avec combinaison. L'agglomération progressive de ces particules, quand on ajoute du précipitant dans la solution provoque une anomalie dans le comportement du coefficient k′ de Huggins. La proportion de microgel varie beaucoup suivant l'origine du polyéthylène: les polyéthylènes Bakélite contiennent plus de microgel que les Plastylènes, mais ceux-ci, en revanche contiennent davantage de molécules à poids moléculaire et taux de ramification intermédiaires. Différentes caractéristiques des diagrammes de Zimm révèlent la structure compacte de ces particules de microgel et la limitation de leur croissance par transfert intermoléculaire. On en conclut qu'on ne peut pas déduire valablement le taux moyen des ramifications à longue chaîne de la comparaison des valeurs de Mw/Mn avec les résultats des calculs cinétiques qui ne tiennent pas compte de cette limitation.

Notes: Melt viscosities of styrene homopolymers and copolymers with 1.5 to 23 mole-% methacrylic acid were measured with a parallel plate plastometer. Apparent viscosities were found to drop off sharply with increasing rate of shear in the range 10-4 to 10-1 sec.-1. An increasing concentration of carboxyl groups led to a pronounced increase in the melt viscosity and the activation energy for viscous flow. Infrared spectra of the copolymers were recorded while the samples were subjected to various thermal cycles. Equilibrium in the dimerization of carboxyl groups was established very rapidly above about 100°C., but the equilibrium was effectively frozen at lower temperatures. Samples as originally prepared by precipitation from dilute solution were further removed from equilibrium than samples quenched from high temperatures. The results are discussed in terms of the rate process theory of viscosity.

Notes: Lorsque l'on irradie du polyéthylène en présence d'air on observe à côté de la réticulation du polymère la formation de ponts peroxydiques. Ces derniers ont été utilisés pour préparer des copolymères greffés. Pour cela des films de polyéthylène préalablement irradiés ont été chauffés à des températures variables dans un monomère vinylique (acrylonitrile, méthacrylate de méthyle, vinylcarbazole). On a constaté que dans ces conditions les films croissent dans le milieu réactionnel jusqu'à des taux de greffage considérables (correspondant à un poids final supeérieur à 100 fois le poids initial). Au cours de cette croissance, la forme extérieure des films reste conservée. On a étudié la cinétique de cette réaction à des températures comprises entre 25° et 192°. L'énergie d'activation de la réaction varie avec la température de greffage. On a trouvé pour le greffage de l'acrylonitrile E = 9,3 kcal au-dessus de 109° et 17,4 kcal en dessous de cette température, tandis que pour le méthacrylate de methple ces valeurs étaient respectivement égales à 8,6 kcal et 16.2 kcal au-dessus et en-dessous de 97°. Ce phénomene a été interprété en remarquant qu'en dessous de 100-l10° le polyéthylène renferme des zones cristallines qui s'opposent à la diffusion libre du monomere et qu'il en résulte un terme additif dépendant de la température et correspondant à l'énergie d'activation de cette diffusion. Au-dessus de 110° les cristallites sont entiléement fondus et le monomére diffuse librement dans le polymére amorphe. A 25° la réaction de greffage est extrêmement faible ce qui permet de stocker le polymère pendant une durée très longue (de l'ordre dune année) sans que l'on puisse noter une diminution de son activité pour le greffage.

Notes: Les propriétés des couches monomoléculaires constituent un moyen d'investigation qui fournit des renseignements sur la grandeur de la molécule, sur sa morphologie e t parfois sur sa structure. C'est l'application de I'osmométrie superficielle qui conduit à la détermination de la masse nioléculaire de certaines macromolécules. De nombreux exemples montrent m e concordance avec les résultats classiques obtenus par d'autres procédés. Cette méthode a été employée avec succès surtout pour les protéines. En ce qui concerne les macromolécules de synthèse, on observe des résultats qui ne sont pas toujours en accord avec les données obtenues par les techniques hahituelles. En général, ces résultats sont moins concordants pour les macromolécules possédant une faible rigidité. Dans ce travail, nous prenons en considération deux cas: une macromolécule assez rigide, e t deux autres plus ou moins flexibles. Nous proposons m e nouvelle méthode dc détcrmination de la masse moléc:ulaire par la viscosimétrie superficielle. Cette méthotle envisage la transposition de l'équation de Staudinger dans l'espace à deux dimensions.

Notes: Die Entmischungs Koeffizienten makromolekularer Stoffe in verschiedenen Lösungsmitteln wurden nach der Trennrohrmethode gemessen. Untersucht wurden die Systeme: Polyvinylpyrrolidon in Wasser und Alkohol; Polystyrol in Toluol und einigen anderen Lösungsmitteln; Polyvinylacetat in Toluol und anderen Lösungsmitteln. Die Abhängigkeit der Soretkoeffizienten vom Molekulargewicht und von der Konzentration wird angegeben. Die Thermodiffusion makromolekularer Substanzen in geeigneten Lösungsmitteln kann zur Fraktionierung und zur Aufstellung von Molekulargewichts-Verteilungskurven herangezogen werden.

Notes: Polymerizability in the thermodynamic sense is measured by the free energy of polymerization. The effect of structure on polymerizability can be measured in two ways: (1) we may compare standard free energies (which are directly related to equilibrium monomer concentrations) at a given temperature; or (2) we may compare the temperatures at which the actual free energy changes are zero for a chosen monomer concentration. These temperatures are termed “ceiling temperatures” Tc and have been determined for the 1:1 copolymerization of sulfur dioxide S. with a wide variety of unsaturated compounds M, under the standard conditions [M] [S] = 27 mole2.1-2(binary mixture, mole fraction of M approximately 0.09). The polymers have the general formula Tc was determined by extrapolating the photochemical rate-temperature relation to zero rate. In the straight chain 1-olefin series Tc falls from ethylene (gt;135°) to propylene 90°, to butene-1 64°, and thereafter remains approximately constant with increasing chain length. With 2-olefins there is a progressive decrease from butene 34°, to pentene 8°, to heptene -38°. Branching invariably lowers Tc and the effect is greatest when the branching is at the double bond: thus isobutene 4°, 3-methylbutene-1 36°, 4,4-dimethylpentene-1 14°. 2-Ethyl substitution of a 1-olefin, or 2, 3 or 4 substitution of a 2-olefin results in inability to react at any temperature down to -80°. Cyclic olefins have Tc considerably higher than the corresponding 2-olefins: cyclopentene 102°, cyclohexene 24°. A number of allyl compounds have also been investigated. Tc is related to the heat and entropy of polymerization by the relation Tc = Delta;H/ΔS and in eight cases values of ΔH and ΔS have been obtained. A change of structure mainly affects ΔH. Estimated equilibrium monomer concentrations in polysulfone formation and in vinyl polymerization at 25°C. are summarized.

Notes: In the viscometric evaluation of poly-6-caproamide (6-PA), the following effects were studied in detail: influence of water in tricresol, influence of molecular weight, and influence of temperature. The water present in the tricresol lowers the measured value of [η] proportionately to the water content. The value of K in the Huggins equation ηsp/c = [η] + K[η]2C remains constant within the limits of experimental errors. The value of K in the Huggins equation was found to be influenced significantly by molecular weight. For low values of [η], the constant K increases manyfold. The constant K was, therefore, replaced by a function which takes account of the increase of K due to the molecular weight: \documentclass{article}\pagestyle{empty}\begin{document}$$ {{K = K_1 + K_2 } \mathord{\left/ {\vphantom {{K = K_1 + K_2 } {[\eta ]^x }}} \right. \kern-\nulldelimiterspace} {[\eta ]^x }} $$\end{document} where K1 = 0.26, K2 = 285.5, and x = 1.48. At higher temperatures, the measured value of [η] decreases, and the constant K in the Huggins equation remains constant within the limits of experimental error. The following equation was used to give the dependence of the viscosity of 6-PA on temperature: \documentclass{article}\pagestyle{empty}\begin{document}$$ \log [\eta ] = {a \mathord{\left/ {\vphantom {a {T + b}}} \right. \kern-\nulldelimiterspace} {T + b}} $$\end{document} where the constant a is independent of [η], while b is a function of [η].

Notes: Bei der Reaktion von Wasserstoffperoxyd mit Eisen(II)-ionen werden primär die OH-Radikale gebildet, die unter Umständen mit weiteren Eisen-ionen oder Wasserstoffperoxyd bzw.mit anderen Komponenten der Lösung reagieren können. Diese Reaktionen machen sich bei der polarographischen Reduktion des dreiwertigen Eisens in der Anwesenheit von Wasserstoffperoxyd geltend. Die auf der Quecksilbertropfelektrode gebildeten Eisen(II)-ionen werden durch Wasserstoffperoxyd zurück oxydiert, was eine Erhöhung der Reduktionsstufe des dreiwertigen Eisens verursacht. Die Stoffe, die leicht mit den Radikalen OH reagieren, unterdrücken die Reaktion der Radikale OH mit Eisen(II)-ionen und verursachen dadurch eine Erniedrigung der katalytischen Stufe. In Anwesenheit von Athanol ist die Erniedrigung besonders gross, da in der Umgebung der Elektrode eine Kettenoxydation des Athanols verläuft, an der Wasserstoffperoxyd, sowie die Eisen-ionen teilnehmen. Die Zusätze der Monomeren zu dieser Lösung führen zu einer Unterdrückung der Oxydation von Åthanol und Erhöhung der katalytischen Stufe. Bei vollkommener Ausschaltung der Kettenreaktion erreicht der katalytische Strom einen Grenzwert. Die dazu benötigte Monomerkonzentration hängt von seiner Reaktionsgeschwindigkeit mit den Radikalen OH ab. Es ist deswegen möglich die polarographische Methode zu der Charakterisation der Reaktivität der Monomeren zu benützen.

Notes: The polymerization curve in emulsion polymerization in presence of retarding substance was determined. The active concentration of the monomer in the vicinity of the growing radical was assumed constant, while the number of reacting particles was varied. The active concentration of the retardant in the vicinity of the reacting radical was assumed constant during the polymerization.The following relationship was derived for the decrease in monomer concentration: \documentclass{article}\pagestyle{empty}\begin{document}$$ - m = k_2 ({\rm M})n\frac{{V'_i }}{{2V'_i + V'_r }}\left[ {t - \frac{n}{{2V'_i + V'_r }}\left( {1 - \exp \left\{ { - \frac{{2V'_i + V'_r }}{{}}t} \right\}} \right)} \right] $$\end{document} where -m, is the decrease in monomer concentration, k2 is the kinetic constant of the chain growth, (M) is the active concentration of the monomer in the vicinity of the growing radical, n is the concentration of all particles in the emulsion, V′t is the velocity of penetration of the initiator radical into the particles; the initiation velocity V′i(n - n1)/n, n1 is the concentration of reacting particles, i.e., of particles containing the growing polymer radical, V′r = nk3[R]; k3 is the constant of chain termination by a retardant molecule; V′in1/n is the velocity of termination by a primary radical, and t is polymerization time. For the polymerization with a constant number of particles we have \documentclass{article}\pagestyle{empty}\begin{document}$$ - m_2 = k_2 ({\rm M})n\frac{{V'_i }}{{2V'_i + V'_r }}\left( {t - \frac{n}{{2V'_i + V'_r }}} \right) $$\end{document} where -m2 is the decrease in monomer concentration during the period of constant polymerization rate. In the presence of a large amount of retardant, when V′r ≫ 2V′i the decrease in monomer concentration is given by \documentclass{article}\pagestyle{empty}\begin{document}$$ - m = k_2 ({\rm M})\frac{{V'_i }}{{k_3 [{\rm R}]}}\left[ {t - \frac{1}{{k_3 [{\rm R}]}}\left( {1 - \exp \left\{ { - k_3 [{\rm R}]t} \right\}} \right)} \right] $$\end{document} This equation shows that for these conditions the decrease in monomer concentration is independent of the number of polymerizing particles, but it is directly proportional to the initiation velocity, and inversely proportional to k3[R]. For the final period at the end of the polymerization, when it can no longer be assumed that the active concentration of the monomer in the vicinity of reacting radical is constant, the following formula was derived: \documentclass{article}\pagestyle{empty}\begin{document}$$ - m_3 = N({\rm M})_0 \left( {1 - \exp \left\{ { - \frac{{k_2 }}{{N_A }}\frac{{V'_i }}{{2V'_i + V'_i }}t_3 } \right\}} \right) $$\end{document} where -m3 is the total decrease in monomer concentration during the period of (M) ≠ const.; N is the number of particles in unit volume of the aqueous phase, NA is Avogadro's number; (M0) is the active concentration of the monomer in the period of constant polymerization rate; and t3 is the time elapsed from the beginning of this period, i.e., total polymerization time minus time of constant (M).

Notes: A range of branched polymers has been prepared by condensing polyvinyl acetate chains containing a terminal carboxyl group, on to a radioactive, partially alcoholyzed backbone of polyvinyl acetate. The important advantage of this process over normal grafting techniques is that the branches may be fractionated and characterized prior to attachment to the main chain. The viscosity behavior of these molecules in dilute solution has been studied, and, although the degree of coiling appears to be similar to that for corresponding linear molecules of the same molecular weight, they do show abnormally high Huggins' constants. Tetrahydrofuran was used as a solvent for the viscosity measurements in order that unreacted hydroxyl groups would not affect the value of the limiting viscosity number and slope constants. Before other solution properties are examined, the polymers will be acetylated in solution with ketene.

Notes: In this paper the influence of different molecular parameters on the dielectric characteristics of amorphous high polymers has been examined. The dielectric behaviour has been compared for several polymers which carry the same dipole in the side chain, but which differ in the flexibility of the main chain (polymethyl acrylate and polymethyl methacrylate) and in the steric hindrance of the side group (methyl, ethyl, butyl, and isobutyl polymethacrylate). Two dispersion zones have been found in the case of polymethyl methacrylate. These may be attributed to the motions of the segments of the main chain and those of the side chains. For each polymethacrylic ester and in the range of frequencies used in these experiments, only one dispersion zone has been found. The experimental results show that it must be attributed to motions of the side groups, which occur simultaneously with the deformations of the main chain. The observed dielectric dispersion do not seem to be of the same nature as those shown by the study of the mechanical properties. The observed dispersions in high polymeric systems probably have their origin in complexes and various molecular motions which need further investigation.

Notes: In a previous paper we gave evidence for the validity of the Einstein-Stokes law for determining molecular dimensions from the diffusion coefficient. In this work, we report on measurements on some polyoxyethylenes in water and on low molecular weight polystyrenes in benzene. The possibility of obtaining exact information regarding the molecular dimensions and the interactions with the solvent have been stated. In high polymers, the dimensions are considerably influenced by the molecular expansion coefficient, α; as a result of this, in studying structural properties of the molecules in solution, the measurements must be carried out in ideal solvents. We have developed a method based on viscometric measurements, which makes possible determination of the composition of the ideal mixture for a given temperature, where such a mixture consists of two components, of which one is a good solvent, and the other is a precipitating agent (non-solvent). Such measurements have been made on 11 fractions of polystyrene from which it has been possible to determine the expansion coefficient α and the dimensions of the unperturbed molecules at 34°C.

Notes: In order to determine the structure and phase state of polymers and to define the spacing of molecular groups of atoms of which molecules of the substance under investigation consist, it is necessary to estimate the mutual distribution of macromolecules. The results of a number of investigations carried out by the electron microscope and by direct structural techniques make it possible to obtain such an estimation. In this work the formation of ordered structures in amorphous polymers has been found by investigating solutions of polymers with the electron microscope. The study of thin oriented films of polymers by the above method confirms the possibility of mutual distribution of amorphous polymer chains and of crystallizable polymer chains after destroying the crystals. In investigating thin films of crystallizable polymers by the x-ray and the electron diffraction techniques at temperatures above and below the crystallization temperatures, a high degree of ordering has been found for the amorphous state of these polymers, too. From the data obtained, the conclusion is to be drawn that a fair mutual ordering of chain molecules can arise even in the amorphous state of polymers. Crystallization of polymers is but the last step in the process of mutual ordering of chain molecules.

Notes: Earlier in our work with Kargin we expressed for the first time the assumption concerning the amorphous structure of cellulose. This assumption was proved in the case of partially oriented fibers and films of hydrated cellulose on the basis of structural mechanical data. A perfect reversibility of the orientation of these fibers was clear from these data as well as a far-reaching analogy between the x-ray diagram of isotropic cellulose and similar diffraction diagrams of amorphous rubber and low molecular weight liquids. At present this conclusion is recognized by many research workers and there are no serious objections to it. It was, however, not clear whether it is possible to apply this statement to “perfectly oriented” hydrated cellulose. There had already been obtained textures with a similar or even higher degree of orientation than with native ramie cellulose. The influence of the orientation on the crystallinity of the fibers of hydrated cellulose in the entire range of extension up to 200% was therefore studied. The x-ray investigation of these fibers according to the criteria of Katz showed that the structure of fibers of hydrated cellulose similar to ramie cellulose as determined from the Debye diagram did not differ significantly from the Debye diagrams of the initially isotropic fibers. From this it necessarily follows that during the orientation of the fibers new elements of symmetry do not arise in their structure. Further x-ray research was directed to studying the differences of the phase structure of hydrated cellulose and its structural modification prepared according to the method of Meyer and Badenhützen by heating completely oriented fibers of hydrated cellulose in a polar liquid. At the same time it was found that the transition of hydrated cellulose to its modification, native cellulose is thermodynamically reversible and that it can be repeated many times. The direct transition of native cellulose to hydrated cellulose occurs spontaneously and is connected only with a decrease of the force acting between the molecules as a result of swelling. The reverse transition, however, requires an increase of the value of kT. This is required only by the differing flexibility of the chains of these modifications of cellulose caused by their differing configuration and not at all by a change of the phase structure of the cellulose.Since the structural criterion is not adequate for the definitive derivation of the phase structure of cellulose, we determined the integral heat of solution of cellulose fibers of differing structure and molecular weight in an aqueous solution of the quaternary ammonium base (C2H5)3NC6H5OH in an adiabatic calorimeter with sufficiently high precision. The results obtained show that the heat content of hydrated cellulose does not change over a wide range of orientation of the fibers and that it does not depend on the molecular weight of cellulose nor on the history of the fiber. The absolute values of the corresponding quantities for native cellulose differ only slightly. They change continuously and without breaks on transforming native cellulose to hydrated cellulose by often repeated xanthogenation and regeneration under the action of mineral acids, without damaging the fiber structure. At the same time this rules out phase differences in the structure of both modifications, hydrated cellulose and native cellulose.

Notes: In research on the kinetics of the inhibition of the thermal polymerization of styrene, we came to the conclusion that quinones participate not only in the inhibition reaction but also in the copolymerization. We carried out the derivation of the basic kinetic equations of the process in two ways: (1) Using the usual simplifying assumptions of the theory of copolymerization (Melville-Watson method) and (2) using the stationary state method. The kinetic equations derived by the second method transform under certain conditions to the corresponding equations of simple inhibition, while the equations from the first method lead to contradictions. On the basis of the kinetic analysis it was found that the inhibition period during copolymerization of the inhibitor does not increase linearly within increasing concentration of the inhibitor, and that on the curve of conversion versus time there is an inflection point if the concentration of inhibitor is higher than a certain value. The curve of initial polymerization velocity against concentration of inhibitor has a minimum at a certain concentration (“inhibition optimum”). Experiments carried out with p-benzoquinone at 90, 105, 120, and 135°C. completely agree with what has been stated above. At the lower temperatures, except for a slight shortening of the inhibition period, no significant indications of copolymerization are apparent; the course of these experiments is well described by the equation of simple inhibition. At 120 and 135°C. copolymerization occurs to a marked extent and is well characterized by the equations derived by the second method. Finally, from the temperature dependence of the appropriate velocity constants, we determined the activation energy of the inhibition reaction (4.3 kcal./mol.) and the activation energy of copolymerization of quinone (9.4 kcal./mole).

Notes: Die mit perjodsäure, Ozon, bzw. Bichromat oxydierten Polysaccharide (z.B. Cellulose, Stärke, Dextrin, Dextran, Xylan) liefern nach Kondensation mit Phenylhydrazin, mit Diazoniumverbindungen intensiv rote Formazane. Diese Polysaccharidformazane ergeben mit Schwermetallsalzen farbige Metallkomplexe. Im Falle der einfachen Formazane, bilden sich die Komplexverbindungen im allgemeinen aus zwei Molekülen Formazan und einem Molekül Metallsalz. Wenn aber in dem Formazanmolekül Hydroxyloder Carboxylgruppen vorhanden sind, nehmen auch diese an der Komplex-bildung teil; es entstehen dann meist koordinativ ungesättigte Komplexverbindungen, in denen sich je ein Molekül der beiden Komponenten vereinigt. Beim Studium der Polysaccharidformazankomplexe diente das einfache D-Galakto-diphenylformazan als Modellsubstanz, an welchem dasselbe Prinzip der Komplexbildung zu beobachten ist. Bei den Metallkomplexen der Polysaccharidformazane sind die Resultate nicht immer so eindeutig, doch kann deren Struktur auch im Sinne der obigen Formeln interpretiert werden. Die Uranylkomplexe der Polysaccharidformazane zeigen an den elektronenmikroskopischen Aufnahmen einen starken Schattungseffekt, so dass hier die Polysaccharide mit ausgeprägten schwarzen Tönen zum Vorschein kommen. Die Resultate lassen hoffen, dass auf dieser Grundlage eine Methode zur Polysaccharidforschung entwickelt werden kann.

Notes: Es wird über osmotische Messungen an Lösungen von Polystyrol (PST) in Toluol und Cyclohexan im Temperaturbereich von 0-50°C. bzw. 30-50°C. berichtet. Der Konzentrationsbereich bis ca. 300 g./l (etwa 30 grundmol prozente) konnte durch Messung der Steighöhendifferenz zwischen eweils zwei Lösungen verschiedener Konzentration erfasst werden. σπ/σx*2 wurde als Funktion von T und x*2 ermittelt und hieraus die Aktivität a1 des Lösungsmittels berechnet (π = osmotischer Druck, x*2 = Grundmolenbruch des Polymerisats, T = absolute Temperatur). Die thermodynamische Auswertung erfolgte nach dem Ansatz \documentclass{article}\pagestyle{empty}\begin{document}$$ \ln \alpha _1 = \ln x_1^* + \left( {1 - \frac{1}{r}} \right)x_2^* + \sum\limits_{i = 1}^n {\chi _i \left( T \right)x_2^{*i + 1} } $$\end{document}(r = Polymerisationsgrad). Die Grössen χI sind empirische Parameter. Sind alle χi = 0, so erhält man die bekannte Beziehung von Huggins und Flory für eine ideal-athermische hochmolekulare Lösung. Das System PSt-Toluol befolgt den halbempirischen Huggins-Ansatz, d.h. χ1 ≠ 0; χ2 = χ3… = 0. Das System ist näherungsweise athermisch. Dagegen sind Lösungen von PST in Cyclohexan endotherm. Dieses System gehorcht der von Tompa erweiterten Huggins-Gleichung, d.h. χ1 ≠ 0; χ2 ≠ 0; χ3 = χ4… = 0. Es werden grundmolare Zusatzfunktionen G*E, S*E, und H*E eingeführt, die den Unterschied zwischen den gemessenen grundmolaren Zustandsgrössen ΔG*, ΔS*, ΔH* und den entsprechenden Grössen in einer ideal-athermischen Lösungangeben (G = freie Enthalpie, S = Entropie, H = Enthalpie). ImSystem PSt-Toluol ist G*E symmetrisch im Grundmolenbruch. Ferner gilt G*E ≈ TS*E 〉 0. Im System PSt-Cyclohexan ist G*E 〉 0, H*E 〉 0, und S*E 〈 0. Hier ist der Verlauf der grundmolaren Zusatzfunktionen unsymmetrisch. Aus dem Temperatur- und Konzentrationsverlauf der Aktivität resultiert für das System PSt-Cyclohexan eine Mischungslücke unterhalb 27°C. Das Ergebnis stimmt mit Entmischungsversuchen befriedigend überein. Dies wird als ein Kriterium für die Zuverlässigkeit der osmotischen Messungen angesehen.

Notes: Elementary sulfur which is educed as a result of the reaction between disulfides, peroxides, and H2S does not cause the vulcanization of rubber. Vulcanization as a process of chemical crosslinking formation occurs when this reaction proceeds with radicals formation (light effect, redox systems). Disulfides and sulfenamides cause the effect of vulcanization passing through the stage of hydrogen separation from α-methylene group, and the formation of polymer radicals. Vulcanizing agent groups join rubber during this process. This is confirmed by isotope exchange of vulcanizate. Conjugated reaction of the linking of sulfur and accelerator to rubber occurs in the presence of mercaptobenzothiazol and sulfur. Intermediate combinations of MBT and sulfur are educed. Monotonous drop of the ability of vulcanizate to exchange with elementary sulfur shows the importance of persulfhydril and polysulfide radicals in reactions of vulcanization.

Notes: The importance of abnormal linkages in polymer degradation processes is well illustrated by the thermal reactions which occur in polymethacrylonitrile. Three quite distinct reactions may be observed in the temperature ranges 20-120°C., 120-220°C., and above 220°C., respectively, and each of these is associated with a different structural tural irregularity. In the low temperature range, in solution, ketene-imine structures disappear with an accompanying limited decrease in molecular weight. These are presumably created during polymerization by reaction of long chain radicals through the cyanide centers They are formed principally in the chain termination process and disappear in a second-order reaction whose rate is strongly dependent upon the viscosity of the medium. Above the softening point of the polymer (120°C.) rapid discoloration through yellow and orange to red occurs. This has been attributed to the progressive linking up of sequences of adjacent nitrile groups to form conjugated structures. The reaction is initiated at methacrylic acid units which are present in small concentration in polymethacrylonitrile as it is usually prepared. The reaction can also be initiated by a variety of other substances containing reactive hydrogen atoms and not necessarily incorporated into the polymer chains. A mechanism has been proposed in terms of well-established chemical processes. Above 220°C. depolymerization to monomer occurs and yields approaching 100% can be attained provided the coloration reaction is suppressed by careful purification of the monomer from which the polymer is prepared. This depolymerization process is superficially similar to that which occurs in polymethyl methacrylate, being initiated most probably by radical formation at the chain terminal structures.

Notes: Butadiene has been polymerized by AlCl3 and related materials at -78°C. The structure of the polymers produced has been studied by infrared analysis. The structure of the soluble polybutadiene was found to be independent of extent of conversion, concentration of catalyst solution, and length of reaction. An insoluble polymer also formed in the system and the amount of this depended on the extent of conversion, being greater at higher conversion whether this was achieved by higher catalyst concentration or longer time. Complexing the AlCl3 with nitroethane or nitrobenzene changed the structure of the polymer slightly, while the use of diethyl ether as a complexer produced no changes. TiCl4, used as the initiator, produced polymers of slightly different structure from those formed with AlCl3, while AlBr3 and BF3·Et2O yielded polymers like those from AlCl3. When the solvent used was varied, the polymer structure also varied. The observed variations were small in all cases.

Notes: 1. Geschwindigkeit und Grad des mechanochemischen Abbaus von wasserhaltigem Sulfitzellstoff sind von den mechanischen Bedingungen der Schwingmahlung abhängig. Nach einer Mahldauer von 900 Stunden wurde ein DP-Wert von 11 (Viskositätszahl) bzw. 7 (Reduktionsvermögen) erreicht. 2. Der lineare Anstieg der Cu-Zahlen mit dem viskosimetrisch ermittelten Spaltungsgrad berechtigt zu dem Schluss, dass der mechanische Abbau von wasserhaltigem Zellstoff im wesentlichen als mechanisch aktivierte Hydrolyse verläuft. 3. Die Wasserlöslichkeit der Mahlprodukte steigt mit fallendem DP erst langsam, dann schnell bis auf etwa 90% an. Demnach erfolgt die mechanische Bindungsspaltung nicht von den Ketteneden her, sondern vorzugsweise zwischen mittleren Kettengliedern. 4. Die bisher unbeachtet gebliebene grosse Wasserlöslichkeit mechanisch abgebauter Zellulose erklärt ihre gute Rekristallisierbarkeit. Nur der wasserunlösliche Anteil, der von dem Abbau den höchsten Kristallinitätsgrad besass, wird nach dem Herauslösen aller aus den weniger orientierten Anteilen enstandenen niedermolekularen Abbauprodukte rekristallisiert.

Notes: Beim Stärkekorn hat man es mit einem natürlich gewachsenen und damit auch organisierten Produkt zu tun, dessen struktureller Aufbau durch die Tätigkeit von Plastiden massgebend mitbestimmt wird. Die vorliegenden Strukturelemente in ihrer Gesamtheit bedingen die mannigfaltigen Eigenschaften der Stärke, wobei jedoch stets zu fragen ist, welchen speziellen Struktur- oder Aufbauelementen des Stärkekornes ein bestimmtes Verhalten der Stärke zuzuschreiben ist. Neben den morphologisch-strukturellen hat man es beim Stärkekorn aber auch mit chemischen Problemen zu tun. Mikroskopische Untersuchungen haben wohl manche Erkenntnisse über den strukturellen Aufbau des Stärkekornes geliefert, doch bleibt es öfters unsicher, ob nicht nur durch die Arbeits- methode bedingte Sekundärstrukturen vorgelegen haben. Die Schichtstruktur des Stärkekornes wird häufig überbetont. Bei den Fragen der stoffichen Zusammensetzung des Stärkekornes und deren Veränderungen machte sich früher das Fehlen einer einfachen Nachweismethode für Amylopektin und Amylose, den beiden Grundkomponenten der Stärke, nebeneinander hindernd bemerkbar. Erst nach Entwicklung der Stärkechromatographie mit Hilfe einer Al2O3-Säule, mit welchem Verfahren es möglich ist, mit Jod farbige Komplexe gebende Kohlenhydrate nebeneinander nachzuweisen, gelang es verschiedene wichtige Entscheidungen im Hinblick auf den Aufbau des Kartoffelstärkekornes zu treffen. Amylopektin und Amylose unterscheiden sich eindeutig durch ihre Adsorptionsfähigkeit an Al2O3, wobei keinerlei Übergänge hervortreten. Während beim nativen Stärkekorn keine besondere Aussenhülle anzunehmen ist, findet man eine solche beim gequollenen Stärkekorn. Erst im Verlaufe der tangentialen Aufweitung des Stärkekornes beim Quellungsprozess kommt es durch Zusammendrängung der Amylopektinstruktur des nativen Kornes zur Ausbildung einer Kornhülle. Chromatographisch lässt sich zeigen, dass diese Hülle aus Amylopektin besteht, im Innern des gequollenen Kornes befindet sich dagegen Amylose. Schon die leichte Trennbarkeit des Amylopektins und der Amylose durch die chromatographische Al2O3- Säle bei Vorliegen einer wässrigen Lösung von verkleisterter Stärke sprach dafür, dass diese beiden Grundkomponenten der Stärke im Stärkekorn nur als Gemenge nebeneinander vorliegen können. Durch 4% ige Alkalilösung in der Kälte gelöste Kartoffelstärke gibt das gleiche Chromatogramm wie verkleisterte Stärke. Aber auch durch kurzzeitige, noch keinen Abbau hervorrufende Schwingmahling in Wasser löslich gewordene Stärke gibt ein Chromatogramm, das demjenigen der verkleisterten und der durch Alkali gelösten Stärke gleicht. Damit kann mit Sicherheit geschlossen werden, dass die beiden Grundkomponenten der Stärke, das Amylopektin und die Amylose, im nativen Stärkekorn nur in Form eines Gemisches vorliegen. Eventuell vorhandene Bindungen können nur sehr schwache sein. Als wesentliches, jetzt meist vernachlässigtes Strukturelement der Stärke dürfte auch das Wasser anzusprechen sein, welches im Stärkekorn in verschiedener Form vorliegen kann. Ein direkter Nachweis von verschiedenartig gebundenem Wasser gelingt durch schonende Entwässerung von Stärke vermittelst Infrarotstrahlen. Man erhält Entwässerungskurven, die Unstetigkeiten zeigen, entsprechend einer sprunghaften Abnahme der Wasserdampfspannung der verschiedenen Wasserarten. Die gebrachten, hauptsächlich mit Hilfe der Stärke-Chromatographie gewonnenen Einblicke in den Aufbau des Kartoffelstärkekornes führen zu einem einfachen Modell des Stärkekornes, das als gesicherte Grundlage für weitere Untersuchungen zu dienen vermag.

Notes: Es ist bekannt, dass Mischungen von Polymeren im selben Lösungsmittel in sehr vielen Fällen zur Phasentrennung neigen. Solche Lösungen sind immer kolloide Lösungen bei denen kolloide Bereiche verschiedener Konzentrationen der einzelnen Komponenten nebeneinander vorliegen. Diese kolloiden Bereiche vereinigen sich dann zu getrennten Phasen, wenn die bei der Vereinigung geleistete Arbeit die Oberflächenenergie der kolloiden Bereiche übertrifft. Durch Erhöhung der Oberflächenspannung des Lösungsmittels mit geeigneten Zusätzen zum Lösungsmittel für das Polymere oder Zusätze die nur einige der Polymeren zu lösen in der Lage sind oder solche Zusätze, die keine der Polymeren zu lösen in der Lage sind, die aber immer die Oberflächenspannung erhöhen, kann man erreichen, dass für längere Zeit die kolloiden Lösungsmittel stabil bleiben und keine Phasentrennung eintritt.

Notes: Es wurde die Synthese eines gegenüber Nickel selektiven und 1,2-Dioximgruppe als aktive Gruppe enthältenden Ionenaustauschers untersucht. Dieses Problem wurde schon früher von Kljatschko studiert, der die Darstellung eines Kunstharzionenaus-tauschers durch die Einführung von Dimethylglyoxim in den Sulfo-Resorcin-Kationen austauscher im Stadium der Kondensation in kurzgefasster Form beschrieben hat. Bei der Anwendung seiner Methode wurde festgestellt, dass sie nicht zu positiven Resultaten führt. Dimethylglyoxim wird dabei aus dem Harze teilweise extrahiert, grösstenteils aber durch die Einwirkung von Formaldehyd zersetzt, und die komplexbildenden Eigenschaften eingebüsst werden. Die Elution von Dimethylglyoxim aus dem Harze kann durch die Einführung der 1,2-Dioximgruppe in das Molekül beseitigt werden, das mit Formaldehyd in Polykondensation treten kann z. B. p, p′-Dioxybenzildioxim; es wird dabei jedoch der destruktive Einfluss von Formaldehyd auf die Dioximgruppe nicht beseitigt. Eine andere Möglichkeit bietet eine geeignete Behandlung des Phenol-Formaldehydharzes. So eignet sich z.B. für eine Nickelaufnahme das o-2,3-Dioximinobutylderivat des Resorcin-Formaldehyd-Harzes. Es besitzt jedoch eine geringe Stabilität, besonders bei erhöhten pH-Werten. Harze mit erhöhter Beständigkeit wurden aus Polystyrol-Harz hergestellt durch die aufeinander folgenden: Propionylierung, Nitrosierung und Oximierung. Das Studium über die Struktur des polymären Materials zeigte, dass die Einführung der Propionylgruppe p-ständig verläuft, während in dem Styrolmonomeren die Propionylgruppe in die ω-Stellung an der Seitenkette eintritt. Das Dioximderivat Polystyrols besitzt für Nickel eine Austauschkapazität von 2 meter/g und das Verfärben des Polymeren bei der Sorption entspricht dem Verfärben der niedermolekularen Dioxim-Nickel-Komplexe. Die von linearen Polystyrol dargestellten Ionenaustauscher besassen nicht die erforderlichen mechanischen Eigenschaften; es wurden also Versuche ausgeführt mit einem Styrol-Divinylbenzol Suspensionskopolymeren (0,3; 1.0% DVB). Es wurden dabei Bedingungen für das Erreichen des erforderten Umsetzungsgrades gefunden. Gegenwärtig wird der Einfluss von der Konzentration des primären Substituents auf die Reaktionsfähigkeit des Mischpolymerisats untersucht.

Notes: Analysis of literature data permits the conclusion that a close link exists between cocatalytic effects and inhibition in cationic polymerization. All compounds described as efficient co-catalysts of isobutene polymerization, e.g., water, alcohols, acetic and trichloroacetic acid, can have inhibiting effects under other conditions. All these compounds can be considered as weak bases able to form a catalytic complex on interaction with aluminum trichloride. It was found that the dependence of the molecular weight of polyisobutene on the ratio of the concentration of the organic base to that of the aluminum trichloride exhibits a clear maximum at the molar ratio of 1:1. A number of simple compounds containing oxygen, sulfur, and nitrogen were investigated, e.g., alcohols, ethers, esters, aldehydes, ketones, mercaptans, hydrogen sulfide, ammonia, amines, and nitriles. The results obtained indicate that co-catalytic activity is not limited to compounds with “active” hydrogen. In the case of acetic and chloroacetic acids, anomalous behavior was found. This is explained by acid-base equilibria between these acids and aluminum trichloride in ethyl chloride solution.

Notes: Nach eingehender Untersuchung der sogenanten Vorkondensation bei der Polyäthylenterephthalatbildung bezüglich des Katalysatoreinflusses, der Reaktionskinetik usw, wird die als Umesterung verlaufende Polyesterbildung studiert. Der Reaktionsverlauf wird durch Viskositätsmessungen verfolgt und es ergibt sich erwartungsgemäss wie bei der “Vorkondensation” eine Reaktion erster Ordnung.

Notes: An attempt has been made to combine the advantages of the rapid, base-catalyzed addition polymerization of caprolactam with the more stable molecular weight distribution given by the much slower polycondensation process. This aim has been achieved by polymerizing the monomer in the presence of sodium hydroxide or carbonate and, at a later stage, introducing a small amount of a second agent which promotes hydrolysis or segment interchange reactions and which thus accelerates the chain length re-distribution of the polymer. The polymerization and molecular weight re-equilibration steps can be conveniently conducted as two distinct, consecutive batch processes or can be operated on a continuous basis. The practical, industrial significance of these results is discussed. Suitable agents promoting the re-distribution reactions include water, 6.6 nylon salt, aminocaproic acid, acetic acid, and n-butyl alcohol. All experiments were carried out at 250°C. under a nitrogen atmosphere and the course of the reaction was followed by measurement of the rate of change of the water-soluble content of the polymer, and of its end group concentrations, solution viscosity and, in part, turbidity titrations of the water-extracted products. An observation incidental to the main aim of this work was that the polycaproamide, after washing with water, contained an excess of free amine end groups over carboxyl terminal units. No chain branching was detectable from solution viscosity or infrared spectral investigations, and the polymer was free from sodium. Similar end group effects have been previously described by Dutch and German workers.

Notes: Durch die Reaktion von Thioharnstoff oder N-Methyl-Thioharnstoffen mit chlormethylierten Polystyrolen oder chlormethylierten Styrol-Divinylbenzol-Copolymeren wurde der völlige Ersatz des Chloratoms durch Isothiuroniumgruppen erreicht. Polythiuroniumverbindungen wurden auch durch die Reaktion von Polyvinylalkohol mit Thioharnstoff in saurer Lösung erhalten; in diesem Fall war der maximale substitutionsgrad ein Drittel der Gesamtmenge der Hydroxylgruppen. Polythiuroniumverbindungen wurden besonders im Hinblick auf die Verwendungsmöglichkeit als Anionenaustauscher untersucht. Von diesem Gesichtspunkt aus waren die Reaktionen, durch welche eine Vernetzung dieses Polyelektrolyten erreicht werden konnte, von besonderem Interesse Vernetzung konnte durch die Reaktion mit Formaldehyd und im Falle der Polyvinyl alkohol-Derivate auch durch Oxalsäure erreicht werden. Zusätzlich zu dem erwarteten Ergebnis der Vernetzungsreaktion - der Abnahme der Quellung - wurde eine ziemlich überraschende Zunahme der Stabilität vieler oder der meisten Isothiuroniumgruppen festgestellt. Während die linearen oder schwach vernetzten Polythiuroniumverbindungen in alkalischen Medium zu Thiolen gespalten werden, verleiht weitgehende Vernetzung einem Teil der Thiuroniumgruppen eine aussergewöhnliche Stabilität. Dieser Effect kann auf die Fixierung der Thiuroniumgruppen in einer ebenen Anordnung zurückgeführt werden, welche die Bildung des intermediären ortho-Derivates stört, das durch die Addition des Anions entsteht. Dass der Effekt nicht allein auf die Substitution zurückzuführen ist, zeigt ein Vergleich der Stabilität von Thioharnstoffderivaten, die verschiedene Substituenten tragen. Er kann auch nicht durch sterische Hinderung erklärt werden, da die Austauschfähigkeit für Anionen sogar im Falle der weitestgehenden Vernetzung unbeeinflusst bleibt.

Notes: Zusammenfassend können wir feststellen, dass der Ultraschall in erster Linie eine Zertrümmerung der Makromolekule bedingt, dass die Ultraviolettbestrahlung neben einer solchen Peptisation auch hydrolytische und oxydative Vorgänge hervorruft, dass aber in beiden Fällen, der Phosphor in seiner organischen Bindung verbleibt. Im Gegensatz hietz lässt die Gammastrahlung anfangs die organischen Molekeln intakt, ihre erste Wirkung spielt sich an der Phosphorbindung ab. Diese Feststellung scheint uns für ein Verständnis der durch Nuklearstrahlung ausgelösten Schädigungen komplizierter organischen Substanzen sehr wertvoll zu sein. Wir finden ja in vielen lebenswichtigen Verbindungen veresterte Phosphorsäure vor und können nach den beschriebenen Versuchen erwarten, dass auch in diesen die Phosphorsäure abgespalten wird, bevor noch irgend eine andere fassbare Schädigungen festzustellen ist.

Notes: Results of research on the dielectric losses and polarization of polymers are presented. In the first and second parts of the paper these behaviors of the polymers are considered for high-elastic state. The dielectric losses are shown to be of relaxation character since they can be described by the segmental thermal motion of polymolecules. The second part deals with effective dipole moments of elementary chain units of macromolecules of the homologous series of methacrylic acid esters. It is stated that for the polymers under consideration the intramolecular interaction is of considerable significance. The third part of the report supplies data on the dielectric losses and polarization research of the same polymers in the glassy state. In this case the losses of relaxation character, called dipole-radical, are observed, as they can be described by the thermal motion of separate polar groups or radicals. The application of the method of effective dipole moments for analysis of the experimental date has brought us to the conclusion that it is the intermolecular interaction which is of greater importance for the dipole-radical losses.

Notes: The relation between concentration of polymer in the precipitated phase and the properties of the system are derived. This relation indicates that, for any polymer, a separation into two liquid phases which agrees with Kruyt's definition of coacervates can be obtained. It is suggested that it is not always correct to distinguish coacervation as a special phenomenon. The experimental results of investigation of the systems: ethanediol-water-phenol-polyamide and acetone-methanol-benzene-polystyrene are presented.

Notes: An earlier investigation of the effects of γ-irradiation on aqueous solutions of sodium deoxyribonucleate showed that a plot of log [η] against log R (where [η] = intrinsic viscosity, R = radiation dosage) was linear at high R with a negative slope of 1.85. According to the theory of degradation of macromolecules, this slope should equal ( -α), where α is defined by [η] = KMα (K = constant, M = molecular weight). Determination by light scattering measurements of the M values of γ-degraded nucleate samples has now shown that [η] = KM1.0; the slope of the log [η] against log R plot was therefore approximately twice that to be expected for random degradation of a single chain. Moreover, M-1 was a linear function of R2 over the whole range from R = 0 and this suggested that the initial nucleate had a random distribution of molecular weights. These observations consitute more positive evidence for the earlier proposal that the decrease in molecular weight of the double-helical nucleate structure during γ-irradiation was caused by two independent and approximately opposite breaks, one in each of the polynucleotide strands, and that the formation of such double breaks was proportional to R2. Heating ruptures these hydrogen bonds and, in accordance with the mechanism proposed, caused a relatively greater decrease in M the larger the previous radiation dosage (R). Titration at 25°C showed that γ-irradiation ruptured the hydrogen bonds, although half of them were still present in the samples of lowest [η]. This change has now been re-investigated by titrations at -0.75°C. which allow the determination of the reversible dissociation curves of the double helices and of the denatured form. The low temperature titrations showed that, unlike the main chain breakdown, the rupture of hydrogen bonds was non-random, those linking adenine and cytosine being broken more easily than those linking guanine and cytosine.

Notes: The weight-loss of a methyl-phenyl silicone resin was determined over the temperature range from 135 to 240°C. and up to approximately 10% volatilization. Weight-fraction volatilized varied linearly with the logarithm of time. The history of such logarithmic processes is reviewed briefly. The empirical rate-equation is discussed in terms of the data. On the basis of a surface-removal experiment, and on the basis of the chemistry of the degradation, a mechanism of Fickian diffusion is proposed, wherein the diffusion coefficient varies exponentially as the degree of crosslinking and shrinkage, while the concentration gradient of volatilizable molecules remains constant.

Notes: Free oxidation of rubbers represents a chain process which, at moderate temperatures, consists of two stages. The first stage, constant oxidation rate, is characterized predominantly by the development of an unbranched chain reaction leading to the accumulation of an intermediate compound of low stability. The second stage, autocatalytic oxidation, represents a degenerated branched process, resulting from the decomposition of intermediate products. Inhibitors of the secondary aromatic amine type lower the oxidation rate in the first stage and sharply increase its duration. The inhibited process activation energy is 21.3 kcal./mole. In the inhibited oxidation, the major part of the combined oxygen is contained in the aldehyde groups. In contrast to free oxidation, in which crosslinking of the chains is the dominant process, in inhibited oxidation, the process of destruction of polymer molecules is predominant at first. The inhibited rubber oxidation rate depends on the concentration of the inhibitor. This dependence is described by a curve with a minimum. During the process of the oxidation of rubber, some of the inhibitor combines with the molecules of the polymer, and the rest is partially subjected to the action of molecular oxygen. There is an increase in the rate of rubber oxidation, at inhibitor concentrations above a given level, which is attributable to the initiating action of intermediate radical products of inhibitor oxidation. The inhibitors of the secondary amine type do not interact with stable rubber peroxides and with hydrocarbon radicals. It was shown, that the N—H bond in the amine molecule is above all responsible for the inhibition effect. It was found that the inhibiting power of amines is a direct function of the mobility of the hydrogen of the NH group. The increase in mobility of this atom is attained by: (1) an increase of the conjugation effect in the inhibitor radical, which results from an increase in the number of aromatic nuclei in the amine molecule; and (2) introduction of electron donor substituents in the position para to the secondary amine in the benzene nucleus. The experimental data obtained and also the contemporary theory of the mechanism of oxidation of low molecular weight hydrocarbons made it possible to suggest a chemical scheme of the rubber oxidation mechanism in the presence of inhibitors of the secondary aromatic amine type.

Notes: A study has been made of the photochemical behavior at 2537 A. of the following substances: 2′-, 3′-, 5′-, and cyclic 2′:3′-cytidylic acids and various preparations of apurinic, ribonucleic, and deaminated ribonucleic acids. The behavior of all the cytidylic acids is qualitatively similar, the photoproduct exhibiting a new maximum at 2360 A. The reaction can be reversed completely in the dark by heating, acidification, or addition of alkai. The 5′-cytidylic acid differs quanlitatively from the other cytidylic acids in that the quantum yield is lower, as is also the extinction of the new maximum. These results are in agreement with previous findings and support the suggestion that there is hydrogen bonding in cytosine nucleosides and nucleotides between the pyrimidine 2-carbonyl and the 5′-sugar hydroxyl which influences the photochemical reaction. The results indicate also the possible existence of weaker bonds involving the 2′- and 3′-hydroxyls. The irradiation of apurinic and ribonucleic acids is accompanied by a decrease in extinction of the principal absorption maximum and very little change below 2400 A. If the decrease of the principal absorption maximum does not exceed 50% as a result of photolysis, then it is subsequently possible to restore about 50% of this decrease by heating a few minutes at 70-90°C. The quantum yield for photolysis of apurinic acid is of the same order of magnitude as for 2′- and 3′-cytidine nucleotides; for ribonucleic acid it is lower. For deaminated ribonucleic acid, the reaction is not reversible. The photochemical behavior of nucleic acids is discussed from the point of view of the photochemistry of uracil and cytosine nucleotides, as well as the relation of the results to the phenomenon of photoreactivation.

Notes: Es wird versucht, den Mechanismus der Radikalbildung aus organischen Hydroperoxyden in homogener Lösung aufzuklären. Die scheinbare Diskrepanz, dass die bekannte thermische Zersetzung von Hydroperoxyden in Lösung kinetisch nach der 1. Ordnung verläuft, dagegen die Katalyse der Autoxydation ungesättigter Verbindungen durch Hydroperoxyde in einer Reaktion 2. Ordnung erfolgt, wird diskutiert und durch eine Arbeitshypothese überwunden. Ihre experimentelle Nachprüfung durch dilatometrische Verfolgung von Polymerisationen lieferte kinetische Ergebnisse, die sich durch folgende einfache Annahmen deuten lassen: (1) Hydroperoxyde bilden in Gegenwart von Styrol freie Radikale nach der Gleichung: Styrol greift also in die Startreaktion ein. (2) In Methylmethacrylat und Vinylazetat bilden Hydroperoxyde Radikale nach der Gleichung: (3) Alkylperoxy-Radikale (ROO·) bewirken einen zusätzlichen Kettenabbruch durch Reaktion mit Makroradikalen:

Notes: The hydrolysis rate of the nerve gas Sarin in aqueous solution may be accelerated by strongly acidic and strongly basic ion exchange resins. Basic resins are more effective than acid resins. Depending on the resin type and internal structure, a diffusional process or the chemical reaction may be rate determining. In distilled water, cationic resins behave as true catalysts, whereas the products of decomposition of Sarin destroy the effectiveness of anion resins. Dissolved salts in the water lower the useful life of both types of resins by replacement of the active hydrogen or hydroxyl groups.

Notes: The effect of initial weight average chain length of addition polymers (polystyrene in benzene) on the degradation parameters is studied in the light of previously developed theories. Results obtained are compared with those of Jellinek and White. An alternative mechanism of ultrasonic degradation of high polymers is suggested. Its mathematical analysis shows that resonant vibration of polymer molecules is possible. Factors affecting mechanism are discussed to account for the discrepancy between theoretical and experimental results.

Notes: The tensile properties of an unfilled GR-S rubber were measured with an Instron tensile tester at strain rates between 0.158 × 10-3 and 0.158 sec.-1 and at fourteen temperatures between -67.8 and 93.3°C. The tensile strength and ultimate strain at the various strain rates and temperatures were superposed to give two composite curves which are functions of a reduced strain rate. From this superposition, the temperature dependence of the ultimate, properties was obtained. The temperature dependence between -53.8 and 71° is essentially the same as obtained by superposing the stress-strain curves and is given by the Williams, Landel, and Ferry equation. From the composite curves and the temperature function, the tensile strength and the ultimate strain can be predicted at any strain rate and temperature, provided heating and wave propagation effects are negligible. The linear viscoelastic properties were obtained from the initial portions of stress-strain curves and are represented by a reduced stress-strain curve.

Notes: The measured viscosity for concentrated solutions of linear coiling polymers decreases with increasing rate of shear. By use of a theory previously derived to explain this phenomena, it is possible to determine the absolute molecular weight of the polymer from measurements of this effect. The necessary data required for this determination are readily obtained using a simple cone viscometer. Since the theory requires only a knowledge of the variation of viscosity with shear rate together with the polymer concentration and temperature to compute the molecular weight, the method is easily applied to any polymer of this general type. This shear rate method for determining molecular weights has been checked by measuring M for a large number of samples of polystyrene and polymethyl methacrylate. Satisfactory results are obtained on these polymers. When the method is used as outlined, it gives a value for M which is close to the viscosity average. For very wide molecular weight distributions, the value found is somewhat higher than the weight average. Since the method is only strictly valid for linear polymers, it appears that it may also be used in conjunction with other molecular weight methods to obtain useful information concerning the extent of branching in the molecules.

Notes: A model is presented that is based on the experimental conditions prevailing during photopolymerization in a free falling stream. When some simplifying assumptions are applied it is possible to correlate quantities which are potentially measurable, such as yield of reaction and number- and weight-average molecular weights, with the spread of times elapsing between subsequent addition steps. In other words, the average time elapsed can be refined to a time distribution curve. In the model, the time elapsed between initiation and forcible termination is subdivided into t time elements. During each of these it is assumed that exactly one of the following must occur: the growth of the free radical to one larger by one monomer unit, natural termination without any change of size, or nothing. The sum of the probabilities of those events, called, respectively, s, f, and i, is, of course, exactly 1. Considering forcible termination of all polyradicals still surviving after t time elements, one can calculate size and weight distribution curves.

Notes: The previous paper discusses the effect of physical state during the irradiation on the fate of the polymer radicals produced. Additional experiments relating to trapped radicals in hydrocarbon polymers are discussed. Three different methods of detection were used; namely, infrared absorption at 5.8 μ, electron paramagnetic resonance, and gasuptake by the irradiated polymer. Conditions for producing trapped radicals at room temperature are that the polymer exist in the crystalline, glassy, or highly crosslinked form during irradiation. Radicals trapped in the crystalline or glassy areas can dissipate either as the result of heating the polymer above Tm or Tg or else by exposure to a radical scavenger, e.g., oxygen or ethylene. The lifetime of radicals trapped in Marlex-50 can be many thousands of hours at room temperature. Radical decay will take place even with storage in vacuum if given enough time. The decay is arrested by holding the sample at liquid nitrogen temperature. Loss in radical activity in Marlex-50 when stored in vacuum is due mainly to delayed crosslinking. Trans-vinylene and vinyl do not appear to enter into the reaction responsible for the decay. A comparison of the decay of radicals trapped in unbranched Marlex-50 with that in a branched low-density polyethylene when stored in ethylene, oxygen, and vacuum was made. The results suggest that although radicals are trapped in the crystalline regions of both polymers, there are differences between the two crystals - the crystals in the low-density polymer do not appear to be as tight as those in the Marlex-50. Delayed oxidation reactions occurring in the crystalline regions of irradiated Marlex-50 when stored in oxygen at room temperature require a number of intermediate steps before appearing as carbonyl. An average of 5 molecules of oxygen per polymer radical was used in forming carbonyl. Delayed main chain scissions occur during this process which cause severe embrittlement and loss in physical properties. Significant improvements in physical properties of Marlex-50 can be achieved through irradiation, but radicals must not be left trapped in the polymer.

Notes: Scale models are described for a stereochemical study of the cellulose chain assuming standard armchair β-glucose residues crystallizing in space-group P21. Infrared evidence about the hydrogen bonding and intensity data for the strongest equatorial and meridional x-ray reflections are utilized in assessing the validity of many models. The structures published by Meyer and Misch and by other workers do not comply with the criteria thus set up. Some fully hydrogen bonded structures, which are likely to form the basis of the most highly ordered regions in cellulose I and II, are discussed.

Notes: An attractive force appears between particles suspended in solutions of macromolecules when there is neither direct interaction between two particles nor energetic interaction between particles and solute macromolecules. The magnitude of this force is of the order of the osmotic pressure of the solution of macromolecules and the range is of the order of the diameter of macromolecules. This force is calculated as a function of concentration, shape, and charge of macromolecules, and it is shown that it becomes stronger in solutions of chain macromolecules or of macromolecules of dissymmetrical shape than in solutions of rigid spherical macromolecules at the same net concentration. If macromolecules have charge, the force can be greatly intensified. In every case numerical estimation is made, and it is found that actually this kind of force can have a remarkable influence on the state of suspended particles. Numerical examples of the critical concentration of particles at their macroscopic aggregation are given. Finally a short description is added on the effect of energetic interaction between particles and macromolecules.

Notes: Sorption and diffusion of C4 and C5 hydrocarbons have been studied in thin films of ethyl cellulose in the temperature range 30 to 80°C. Only regions of low penetrant concentration were chosen in order to minimize hysteresis effects associated with slow relaxation of polymer chains. The data have been quantitatively compared with those for the same penetrants in rubber, since ethyl cellulose and rubber are examples of stiff and flexible chain polymers, respectively. In both solution and diffusion some major differences were found between the two types of medium. In rubber the heats of dilution were small and the corresponding positive entropies close to those predicted by the lattice theory of solutions. On the other hand, in ethyl cellulose at low penetrant concentrations the heats of dilution were strongly exothermal and the entropies negative. For both polymers diffusion coefficients of penetrants were dependent upon concentration, but whereas in rubber this concentration dependent decreased rapidly with rising temperature, in ethyl cellulose it was largely independent of temperature. Energy barriers involved in each unit diffusion process were comparable for a given hydrocarbon in rubber and in ethyl cellulose, while the molecular shape of the penetrant molecule substantially influenced the diffusion coefficients in each polymer. Further interpretation of the diffusion coefficients suggested that the involvement of polymer chains in each unit diffusion is much less for ethyl cellulose than for rubber. Explanations are offered, based upon the nature of the chains composing the two media and upon the existence of holes in the ethyl cellulose network, for the essential differences indicated above. The relative efficiency of ethyl cellulose and rubber membranes for gas separation is discussed.

Notes: The intermolecular contribution to light scattering by polymer solutions has been treated according to the smoothed Gaussian sphere model. Combining the results with the usual term for the individual molecule scattering we obtain for the reciprocal turbidity: \documentclass{article}\pagestyle{empty}\begin{document}$$ {{Kc} \mathord{\left/ {\vphantom {{Kc} I}} \right. \kern-\nulldelimiterspace} I} = {1 \mathord{\left/ {\vphantom {1 {MP}}} \right. \kern-\nulldelimiterspace} {MP}}\left( \theta \right) + 2Q\left( \theta \right)A_2 c + \ldots $$\end{document}The third virial term is also formulated. The angle dependent factor Q(θ) falls appreciably below unity at higher angles for large molecules in good solvents. Calculation of Q(θ) according to the theory is illustrated. Its replacement by unity may under some circumstances invite appreciable error.

Notes: The thermal coloration which occurs in copolymers of methacrylonitrile with small amounts of methacrylic acid has been studied at 140°C. The infrared spectra of colored polymers show a decrease in nitrile absorption (which has been followed quantitatively) and new absorption appears, mainly at 1693-1490 cm.-1 No volatile material is lost during coloration and molecular weight measurements show that neither chain scission nor crosslinking is involved. Copolymers of different compositions have been used to control the length of sequences of adjacent methacrylonitrile units, and it has been found that coloration is inhibited by larger concentrations of methacrylic acid. Colored polymer slowly reverts to the original material in solution, and rapid decoloration is effected by addition of aqueous solutions of acids, alkalis, and salts. A structure has been deduced for colored polymethacrylonitrile analogous to those proposed previously for paracyanogen and colored polyacrylonitrile. Essentially this is the results of the linking up of adjacent nitrile groups to form conjugated carbon-nitrogen sequences of considerable length. It is suggested that this structure is formed in a nonradical chain process initiated at methacrylic acid units and propagated through adjacent nitrile units. The changes in solubility properties are not the result of crosslinking but of the rigidity of the modified polymer structure.

Notes: The infrared spectrum of polystyrene has been obtained in the region of 70 cm.-1 to 3200 cm.-1. These data, plus Raman scattering data from the literature, are used to make a complete assignment of the normal modes of the polystyrene molecule. The benzene ring modes have been analyzed in detail in terms of C2v symmetry, and a set of normal vibrations has been proposed. On the basis of previous analyses of the benzene and monosubstituted benzenes, and a study of the combination bands, it has been possible to make a fairly satisfactory assignment of all of the benzene ring fundamentals. Assignments of the CH2, CH, and skeletal modes are made on the basis of previous studies of spectra of high polymers. The interpretation of the spectrum is in agreement with other evidence that the chain configuration is a random one, i.e., that the polymer is amorphous.

Notes: Intrinsic viscosities of cellulose acetates of degrees of substitution 2.86 and 3.00 and of cellulose trinitrate have been investigated as functions of temperature, solvent, and molecular weight. Large negative temperature coefficients (ca. -0.6% per degree) of [η] appear to be characteristic of cellulosic chains. These observed decreases in [η] with temperature are due to increases in chain flexibility, which are reflected in decreases in the characteristic ratio r02/M. The rather large variations in [η] with the solvent are shown also to be manifestations of altered chain flexibilities brought about in some manner, as yet unexplained, by specific solvent interaction. This behavior stands in marked contrast to that of other polymers for which r02/M is independent of the solvent and varies only slightly with temperature, and for which solvent effects on [η] are wholly attributable to changes in the molecular expansion (α3) brought about by solvent action,

Notes: Vinyl stearate has been polymerized by 1000 kv. electrons with field intensities ranging from 1.0 × 103 to 20 × 103 rep per second; the polymers are considered to be branched. A discontinuity of reaction rate and molecular weight with respect to temperature was noted in the vicinity of monomer melting point, and it is suggested that in this temperature region, the diffusion constant for propagation is easily affected. A linear relationship between field intensity and polymerization rate, and a constancy in molecular weight with varying field intensities, at constant total dose, indicated that polymerization occurs in “volume elements.”

Notes: Taking, as the samples for investigation, filaments of viscose rayon (60% crystallinity) and acetate rayon (54% acetyl) both crosslinked to various extents by tetramethylenebisethylene urea and tetramethylenediisocyanate urea as the crosslinking agents, the dynamic and transient moduli, E′, G1, G2, the internal friction, Q-1, and the apparent activation energy for relaxation of segment, ΔU, were measured and the results were considered in their relation to the degree of crosslinking. From the results, the following conclusions were made: (1) When crosslinking is caused by long molecular chains of the crosslinking agents between the nearest neighboring molecules, the intermolecular spaces are widened to some extent and the restraint of segmental motion due to the dipole interaction of the strong polar hydroxyl groups is partly relieved so that the decreases in ΔU, E′, G1, and G2 are rather caused by a small amount of the crosslinking agents; for example, while the values of ΔU and E′, for the original viscose rayon not crosslinked are 230 kcal./mole and 2.0 × 1011 dynes/cm.2, respectively, they both decrease with an increase in degree of crosslinking and each shows a minimum (ΔU = 95 kcal./mole, E′ = 0.9 × 1011 dynes/cm.2) at the amount of bound nitrogen N = 0.73%. When the crosslinking proceeds further, the primary crosslinking effect makes its appearance so that ΔU, E′, G1, and G2 begin to rise with an increase in degree of crosslinking. (2) Due to the strong solvating or plasticizing effects, the water molecules absorbed bring about a strong decrease in the apparent activation energy; ΔU = 90 kcal./mole at 80% RH, 200 kcal./mole at 66% RH, and 210 kcal./mole at 55% RH for viscose rayon.

Notes: The copolymerization of vinylene carbonate VC (M2) with several vinyl monomers (M1) has been examined. The reactivity ratios r2 and r1 have been determined in the system VC-vinyl acetate (0.27 and 3.0), VC-vinyl chloride (0.09 and 5.2), VC-vinylpyrrolidone (0.4 and 0.7), VC-methyl methacrylate (〈0.01 and ∼70). These values indicate for vinylene carbonate in the Alfrey-Price scheme a reactivity Q equal to 0.012 and a polarity e of -0.6. From the r1 and r2 parameters of the system vinyl acetatevinylpyrrolidone (0.38 and 0.44, respectively) the Q and e values of vinylpyrrolidone have also been determined: Q = 0.11 and e = -1.6. The copolymers of vinylene carbonate and vinyl acetate yield on hydrolysis polyalcohols —(CH2CHOH)x—(CHOH)y— of which the solubility decreases with increasing content of hydroxyl groups.

Notes: Results of high field conductance measurements on solutions of polyacrylic acid, polystyrenesulfonic acid, and poly-4-vinyl-N-n-butylpyridinium bromide have been presented. All the samples studied required appreciable time to reach a steady conductance value after the application of field, this effect diminished with increasing field, was the largest for PSA samples, intermediate for PVPBuBr samples, and smallest for the PAA samples. The extrapolated relaxation times ranged from 2 to 20 microseconds. In the one case where the results for solutions with appreciably different molecular weight polymers could be extrapolated, it appeared that the time lag increased with increase in molecular weight. The high field conductance quotients increased linearly with increasing field in a manner characteristic of weak electrolytes such as acetic acid, but the observed conductance increases were from 6 to 55-fold larger than for acetic acid at the same field strength. The slopes of the conductance-versus-field curves varied as the degree of neutralization or quaternization was varied, indicative of differing degrees of association. In the one case, PAA, where there was appreciable change in the concentration of the samples studied, the high field conductance quotient decreased with increasing concentration, corresponding to an increase of association with increased concentration. Also with PAA, the Wien effect increased with increased molecular weight.

Notes: The properties of soluble complexes formed in acetate buffer solutions from sodium desoxyribonucleate and serum albumin have been studied by a light scattering method. It has been established that the molecular weight, size, and shape of the complexes formed are influenced by pH, ionic strength, and the proportions and total concentration of the components. At ionic strength 0.04 and about -a 1:1 weight ratio of the components, no binding of albumin by nucleate has been observed at pH higher than 6.0. With continuously decreasing pH, an increasing number of albumin molecules is bound by individual nucleate molecules; this causes stretching of the nucleate molecules and an increase in the excluded volume. At pH 5.5 crosslinking begins. This causes the nucleate molecules to shrink. The concentration of non-bound albumin becomes negligible, and forces of attraction act between the complex particles in solution. With further lowering of the pH, the molecular weight of the complex increases until, at pH 5.1, precipitation of the complex occurs. Qualitatively, the same picture is obtained if we follow the influence of ionic strength at pH 5.3 and the weight ratio of the components. The formation of the complex begins at an ionic strength below 0.20, and crosslinking and complex precipitation occur at ionic strengths of 0.06 and 0.02, respectively. The lowering of the nucleate to albumin ratio has an effect similar to that of lowering of pH or ionic strength. The molecular weight, size, and shape of the complex are stable only in a limited concentration range. At too high concentrations, complex precipitation occurs, and at too low concentrations, there is dissociation of the complex. Ultraviolet absorption measurements indicate that purine and pyrimidine bases of nucleate do not participate in the binding of albumin. It is assumed that albumin is attached to the nucleate by electrostatic forces between positively charged groups of protein and negatively charged phosphate groups of nucleate only.

Notes: Polymere wurden hergestellt, die der bekannten Regel über den Zusammenhang zwischen Porosität und Vernetzeranteil nicht gehorchen. Mit inertem Zusatz polymerisieren Kettenbildner und vernetzende Monomere zu Kopolymeren, dessen Quellung, Hydratation, Diffusionskonstante, innere Oberfläche, Maschenweite, also Porosität den bekannten Daten nicht entsprechen. Die Porositätsunterschiede, die auf Veränderung des Vernetzeranteils entstehen, können mit inerten Zusatzstoffen bis in die entgegengesetzte Richtung verschoben werden. Ein Molekülsiebeffekt wurde an Ionenaustauscherharzen mit unverändertem Vernetzeranteil erzielt.

Notes: The current disagreement as to whether the acid denaturation of DNA produces reversible or irreversible changes of macromolecular configuration can be resolved by paying proper attention to the temperature dependence of the denaturation process. Light scattering measurements have been made on a sample of sodium desoxyribosenucleate taken to pH 2.6 and reneutralized at 0 and 25°C. in 0.1 M NaCl. Whereas the material, acid treated at 25°C., is irreversibly collapsed (radius of gyration = 1370 A., molecular weight unchanged), 0°C. titration leaves the size of the DNA molecule unchanged (ρ = 2800 A.). Viscosity measurements at 0°C. and pH 2.6 show that at this pH the DNA is nearly as fully extended as in neutral solution ([η] = 40 dl./g. compared to 63 dl./g. in neutral aqueous salt solution). However, collapse occurs at pH 2.6 between 0 and 25°C., and this thermal denaturation at pH 2.6 is irreversible. The light scattering properties of acid-denatured DNA are interpreted in terms of a more heterogeneous distribution of macromolecular configurations than in the native material.

Notes: The copolymerization of methyl methacrylate and styrene has been investigated using metallic lithium as an initiator. The unusual composition of the polymer produced does not permit description of lithium as either a classical ionic or radical initiator. A new concept must be adduced to explain the observed results.

Notes: A study has been made of the kinetics of heat inactivation in light and heavy water, of lysozyme, ribonuclease, and desoxyribonuclease. In all instances, the isotope effect for inactivation (kH/kD) is found to be related to the activation energy and to decrease to approximately unity for low activation energies. For lysozyme at acid and neutral pH and for ribonuclease at acid, neutral, and slightly alkaline pH, the results indicate that hydrogen bonding is not of great importance for enzymatic activity, in agreement with the results of previous studies in ordinary water. For desoxyribonuclease at neutral and alkaline pH, the isotope effect varies from 1.5-5.0 which, in agreement with the high values of the thermodynamic constants for heat inactivation of this enzyme, suggests that the rupture of a considerable number of hydrogen bonds is involved in this process. Although the heat inactivation of this enzyme in the pH range 2.4-3.2 in H2O is partially reversible on cooling (if 50% inactivation is not exceeded), no such reversibility was found in D2O; it is believed that this may be due to a decrease in the pK of the protein carboxyl groups in heavy water. It was also found that the isotope effect decreases with temperature, as is to be expected, the result being a small increase in the activation energy and entropy change for the inactivation process in heavy water. The results are discussed, and it is shown that no general conclusion may be drawn from studies on a single enzyme (or protein), but that the findings must be considered individually in relation to structure, deuterium exchange in solution, titration curve in heavy water, etc. Suggestions for further studies are advanced.

Notes: Results obtained in the investigation of polymers containing pentavalent phosphorus in the main polymer chain are presented. A number of polyamides and polyesters derived from phosphorus-containing dicarboxylic acids have been synthesized. Two types of dicarboxylic acids were used: alkyl- or aryl-phosphinic acids (I) and bis-carboxyphenyl-phosphine oxides (II): their chloroanhydrides or esters being used in the reaction. To obtain polyesters, various glycols or dihydric phenols were used as the second component. For preparing polyamides, aliphatic diamines were used as the second component. The nature of the starting materials has a very marked effect on the properties of the polymers obtained. Polyesters with an aliphatic chain are viscous, thick oils or low-melting resins. Polyesters with aromatic unit are high-melting, solid elastic substances. Comparison of the properties of the polymers synthesized by us with the properties of polymers of related composition not containing phosphorus, shows that the introduction of phosphorus into the chain leads to molecules of much greater flexibility. For this reason the softening points of the phosphorus-containing polymers are much lower than those of their carbon analogues.