bluuebunny/crossref_metadata_2025 huggingface dataset:
Copolymérisation de l'anhydre sulfureux et des oléfines
Authors: Jobard M. A.
Published: April 2003

La radiopolpmérisation sous l'effet des rayonnements gamma de mélanges équimoléculaires d'anhydride sulfureux et d'oléfines, a été effectuée à diverses températures. Il a été montré qu'en particulier dans le cas du couple butène–SO2, la température plafond de ce couple se retrouvait être de 63°C, et que la vitesse de copolymérisation était rapide à basse température. La réaction est du type radicalaire. La copolymérisation du même couple réalisée en présence de divers peroxydes met en évidence une plage de température, variable selon le catalyseur, et pour laquelle la vitesse de copolymérisation est maximum.
Synthèse des copolymères greffés a partir des polymères ayant subi l'action des radiations ionisantes. I. Caractères généraux de la réaction de greffage sur le polyéthylène préirradié
Authors: Chapiro Adolphe
Published: April 2003

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.
Polyacrylamides dérivés d'amides cycliques
Authors: Parrod J. , Elles J.
Published: April 2003

Nous avons préparé les acrylamides de formule générale suivante:
magnified image

A = CH2:

Pipéridide acrylique:

C8H13ON

E15

114°n20D

= 1,5060d204

= 1,023

A = 0:

Morpholide acrylique:

C7H11O2N

E16

135°

= 1,5080

= 1,114

A = S:

Thiomorpholideacrylique:

C7H11ONS

E13

150°

= 1,5602

= 1,165

Pyrrolidide acrylique:

C7H11ON

E14

115°

= 1,4990

= 1,030

La meilleure méthode de synthèse au laboratoire consiste à traiter le chlorure d'acroyle par l'amine en présence de triéthylamine, en solution dans le benzène ou le toluène à une température inférieure B 10°. Ces monomères réagissent dès la température ordinaire sur les amines cycliques en donnant des combinaisons saturées.

β Morpholino‐propionyl‐morpholide

C11H20O3N2

F:91‐2

β Pipéridino‐propionyl‐pipéridide

C13H24ON2

F:45°

β Pipéridino‐propionyl‐morpholide

C12H22O2N2

F ∼ 25°

β Pyrrolidino‐propionyl‐morpholide

C10H20O2N2

F = 67°

β Morpholino‐propionyl‐pipéridide

C12H22O2N2

F ∼ 0°

En vue d'une étude comparative, les polymères ont été uniformement preparés en chauffant a 50–60° pendant plusieurs heures une solution du monomère en présence de 0,5% d'azoisobutyronitrile, puis fractionnés par précipitation. Seul le polymorpholide se dissout dans l'eau; le polypyrrolidide et le polypipéridide se dissolvent dans le benzène, tandis que le thiomorpholide est insoluble dans les deux solvants. Les coefficients de la loi [η] = KMa ont été determinés.
Particle size and the rate of emulsion polymerization: A comparison of results obtained by electron microscopy and light scattering
Authors: Burnett G. M. , Lehrle R. S. , Ovenall D. W. , Peaker F. W.
Published: April 2003

The number of particles in an emulsion latex has been determined using standard light scattering apparatus. The values determined are shown to agree closely with those observed using electron microscopy either by direct count methods or by measurement of the dimensions of the particles. For the emulsion polymerization of styrene these self consistent measurements lead to a value of about 60 1. mole−1 sec.−1 for the propagation rate constant.
The configurational statistics of polymeric chains
Authors: Volkenstein M. V.
Published: April 2003

A short review of the works of the author and his co‐workers in the field of configurational statistics of macromolecules is given. Results are quoted of the calculations relating the dimensions, dipole moments, and optical anisotropies of the chains with the conditions of internal rotation and stereoisomerism. Isotactic and syndiotactic chains are examined. The fundamental ideas of the mathematical methods developed are quoted. The calculations are carried out in usual approximation assuming the independence of the rotations around neighbor bonds, and in the next approximations taking into account the correlation of internal rotations inside monomeric units and between them. Comparison of the theory with experiment, using the rotational‐isomeric approximation, has shown in particular that the dimensions and the optical anisotropy of the polyisobutylene molecules can be explained by the examination of their configurations in the crystalline state. The excluded volume effects in the branched chains and their influence on the asymmetry of light scattering are investigated. Some experimental results are explained with the help of this investigation.
Etude physicochimique d'une cryoglobuline
Authors: Guinand Sylvanie
Published: April 2003

Les cryoglobulines sont des protéines du syérum pathologiquc qui précipitent à froid et peuvent perdre cette propriété par passages successifs de 37° à 4°. Nous nous proposons dans ce travail d'étudier par la diffusion de la lumihre et par ultracentrifugation la structure de cryoglobulines pécipitant sous forme de gels et de voir si on peut mettre en évidence des transformations au cours des précipitations et dissolutions successives. L'ultracentrifugation montre qu'il y a un constituant principal M (87 ou 93%) dont la constante de diffusion est 17,6 S, un constituant plus rapide M2 (7 ou 12%)s2c = 24,5 S et dans certains cas un constituant M3 = 34 S, à l'état de traces. L'étude par diffusion de la lumière a permis de determiner pour le constituant principal le poids moléculaire M1 = 1.150.000 ± 100.000. Les valenrs des coefficients de dissymétrie et du facteur de dépolarisation montrent que la molécule doit ê un bâtonnet dont le facteur d'anisotropie δ = ±0,25; on peut l'assimiler a un ellipsolde trks allonge dont le grand axe a pour longueur 1050 ou 1150 A. suivant le signe de δ. Le calcul du facteur de frottement f/fo à partir de la constante de sédimentation et du poids moléculaire déterminé par diffusion de la lumiére montre que le rapport des axes est d'environ 26. Lorsque la cryoglobuline a perdu la propriété de précipiter à f'roid, le poids moléculaire. et, les dimensions ne sont pas changés. Mais on observe une modification du diagramme de sédimentation. L'augmentation de la pente de la droite de régression s20 = f(Δn), traduit une augmentation de la pente de la droite de régression s200 = f (Δ n), traduit une augmentation de I'interaction par suite probablement du démasquage de groupes réactifs.
Thermodiffusion von makromolekülen in lösung
Authors: Langhammer G.
Published: April 2003

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.
Über die ultraschall‐polymerisation von acrylnitril
Authors: Edelmann Kurt
Published: April 2003

Die Polymerisation von Acrylnitril wird durch Radikalc ausgelöst. Behandelt man daher eine wässrige Acrylnitril‐Lösung mit, Ultraschall, so findet Polymerisation statt. Infolge der äusserst geringen Löslichkeit des Acrylnitrils in Wasser, werden in dieser Arbeit konzentrierte Lösungen von Acrylnitril in Dimethylformamid mit unterschiedlichen Mengen Wasser versetzt und beschallt. Durch die Ultraschalleinwirkung werden Wassermoleküle in H‐ und OH‐Radikale aufgespalten, und die OH‐Radikalt. lösen die mit der Zeit fortschreitende Polymerisation des Acrylnitrils aus. Diese Polymerisation findet nur solange statt, wie OH‐Radikale vorhanden sind, d. h. solange der Ultraschall auf die Lösungen einwirkt. Beschallt man jedoch eine konzentrierte Lösung von Acrylnitril in Dimethylformamid unter Zngabe von Schwefelsäure, so beohachtet, man, im Gegensatz zur wässrigen Lösung, während der Beschallung keinerlei Polymerisation. Erst nach beendeter Beschallung setzt die Polymerisation ein und verläft mit wesentlich grösserer Geschwindigkeit. In diesen beschallten Lösungen wird die Anwesenheit von H2O2, H2SO5 und H2S2O8 festgestellt. Daher ist die Polymerisation auf die aus den Peroxy‐Verbindungen gebildeten Radikale zurückzüfuhren, die auch nach der Beschallung vorhanden sind und damit auf das Acrylnitril einwirken. Dieser Effckt erklärt das unterschiedliche Verhalten der Lösung von Acrylnitril in Dimethylformamid bei Anwesenheit von Wasser und von Schwefelsäuve unter der Einwirkung von Ultraschall.
Einfluss einiger monomeren auf die polarographische stufe der eisen(III)‐ionen in gegenwart von wasserstoffperoxyd
Authors: Matyska B. , Dousek F. P.
Published: April 2003

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.
Die mechano‐chemische depolymerisation von kartoffelstärke durch schwingmahlung
Authors: Grohn H. , Augustat S.
Published: April 2003

(1) Die Mahlung von Kartoffelstärke in Schwingmühlen führt bei nicht zu hohem Verhältnis des Mahlgutgewichts zum Mahlkörpergewicht (am zweckmässigsten sind Füllverhältnisse um 1%) nicht nur zu einer mechanischen Zerstörung des Stärkekorns und damit zur Kaltwasserlöslichkeit des Polysaccharids, sondern darüber hinaus zu einer beträchtlichen Depolymerisation der Makromoleküle der Amylose und des Amylopektins unter Bildung von Dextrinen. (2) An zwei verschiedenen Versuchsreihen, die sich durch das Füllverhältnis und das Material der als Mahlkörper dienenden Kugeln unterscheiden, wird gezeigt, dass die Vermahlbarkeitsgrenze von den besonderen mechanischen Bedingungen abhängt, unter denen die Schwingmahlung vorgenommen wird. Die mittels Reduktionswertbestimmungen ermittelten DP‐Werte betragen an den Vermahlbarkeitsgrenzen der beiden Versuchsreihen etwa 32 bzw. 13 Anhydroglucose‐Einheiten. (3) Die Depolymerisation der Kartoffelstärke bei der Schwingmahlung konnte auch durch potentiometrische Titration mit Jod sowie durch Verfolgung der Jodfärbungen der Mahlprodukte nachgewiesen werden. Mittels Blauwertmessungen wurde ein quantitativer Einblick in den Abbau der Amylose erhalten, die unter den gewählten Versuchsbedingungen nach 120stündiger Schwingmahlung der Stärke völlig zu mit Jod‐Kaliumjodid‐Lösung eine rotviolette bzw. rote Färbung gebenden Dextrinen abgebaut war. (4) Die Alkalilabilität von schwinggemahlener Stärke steigt mit zunehmender Mahldauer an. Vergleichende Untersuchungen über die Mahlwirkung in verschiedenen Medien (Sauerstoff, Luft, Stickstoff) lassen keinen bevorzugten Abbau in Sauerstoff erkennen und schliessen deshalb oxydative Nebenerscheinungen als nicht in Betracht kommend aus. (5) Thermische Abbaureaktionen während der Schwingmahlung von Stärke sind nicht anzunehmen, da die Mahlung bei −15°C zu keiner Verminderung des Mahleffektes im Vergleich zu der Mahlung bei Normaltemperatur führt. (6) Die Mahlwirkung hängt vom H2O‐Gehalt der zu vermahlenden Stärke ab. Unter den gewählten Versuchsbedingungen ist der Mahleffekt bei einem H2O‐Gehalt der Stärke in Höhe von 7% höher als bei einem H2O‐Gehalt von 2%. Bei H2O‐Gehalten über 7 bis 8% wird die Mahlwirkung wegen des teilweisen Anbackens der Stärke an der Mahlgefässwandung herabgesetzt. (7) Es wird die Hypothese aufgestellt, dass es sich bei dem Abbau von Stärke durch Schwingmahlung um eine mechanisch aktivierte Hydrolyse handelt.
The formation of crosslinks in cellulose during nitration
Authors: Sihtola Hannes , Anthoni Berndt , Virkola Nils‐Erik
Published: April 2003

Nitrates of cellulose oxidized with periodate are incompletely soluble. By means of sedimentation and diffusion experiments it has been established that this phenomenon is due to crosslinks formed during nitration. On the basis of these results investigation was made whether crosslinks are formed during a nitration if, before nitration, cellulose is impregnated with some small‐molecular compound containing two functional groups. The compounds used were oxalic, glyoxylic, and sebacic acids. The results obtained by the use of the two first mentioned acids were not quite clear. The nitrates of linters impregnated with sebacic acid, and nitrated by the use of a nitration acid prepared from 100% nitric acid, were only partly soluble in acetone. If the linters were hydrolyzed before the impregnation, the nitrates then prepared were completely soluble. In this case also, the increase in viscosity reveals the formation of crosslinks. Cellulose oxidized with periodate was extracted by means of NaOH solution. A qualitative test showed that oxalic, glycolic, and lactic acids were present in the solution.
The synthesis of branched chain polyvinyl acetates
Authors: Melville H. W. , Peaker F. W. , Vale R. L.
Published: April 2003

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.
Thermal degradation of polymethacrylonitrile. III. Structural abnormalities and degradation processes
Authors: Grassie N. , McNeill I. C.
Published: April 2003

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.
On the mechanism of the polymerization of ϵ‐caprolactam. II. The polymerization in the presence of water
Authors: Hermans P. H. , Heikens D. , Van Velden P. F.
Published: April 2003

Kinetic runs were performed at two temperatures with ϵ‐caprolactam–water mixtures containing from 5 to 10 mole‐% of water. The concentrations of unconverted lactam x and endgroups c were determined, and in some cases also the concentration of aminocaproic acid u1 and the quantity of cyclic oligomers formed. The concentration of water w and that of the amide groups in linear molecules were calculated from the boundary conditions. In the evaluation of the kinetics of the reaction, which run towards an equilibrium state, values of the equilibrium constants from previous determinations were used. The course of c can be satisfactorily fitted in with the picture of hydrolysis of the lactam, followed by polycondensation. The former starts off as an uncatalyzed reaction between lactam and water but is soon dominated by hydrolysis catalyzed by endgroups. The quantity of lactam thus converted appears to be only a small fraction of the total lactam conversion. If it is assumed that the bulk of lactam disappears through a reaction with rate proportional to xc2, satisfactory fit with the experiments is obtained. This reaction is interpreted as an endgroup catalyzed polyaddition, i.e., an addition of lactam onto an endgroup of a linear molecule catalyzed by another endgroup. From the determinations of aminocaproic acid concentration u1, confirmatory evidence can also be derived that conversion of this linear monomer is for the major part due to an endgroup catalyzed reaction with lactam of a rate proportional to xu1c and with a rate constant of the same magnitude as that pertaining in the general polyaddition reaction. It is argued that the existence of polyaddition also requires transamidation reactions between linear molecules in which one chain with its endgroup reacts with an amide group of a second chain under formation of two other chains of different lengths. This reaction will tend to produce random chain lengths and will thus accelerate the attainment of a normal Flory‐Schulz MW distribution in the reaction product. The rate of formation of cyclic oligomers during polymerization is also in line with the assumption that these substances are mainly produced by a transmidation reaction of a chain endgroup with an amide group of the same chain, rather than by cyclic condensation of a chain of the required length. A survey of rate constants is given. There is general agreement with those given by Wiloth.
Physico‐chemical study of an antigen‐antibody interaction (preliminary light transmission and light scattering investigations)
Authors: Kratohvil J. , Ajduković Dj. , Muić N.
Published: April 2003

The interaction of Ammodytes viper venom and the corresponding antivenin was followed by light transmission and light scattering measurements. The influence of the ratio of the venom/antivenin concentrations, of the ionic strength and pH of the reacting solution, and the kinetics of the reaction were investigated. The precipitation curve (turbidity versus venom/antivenin ratio) was of the flocculation type and showed a maximum. This maximum corresponded to the neutralization point as revealed through the measurement of the haemolytic activity of venom and antitoxic potency of antivenin. Sodium chloride, sodium sulfate, and ammonium sulfate inhibited the precipitation reaction. The rate of the reaction decreased with increasing concentrations of the salts. The turbidity versus pH curve showed a flat maximum in pH range 5 to 8. The reaction was almost completely retarded at the pH below 4 and above 10. The weight‐average molecular weight of venom, as determined by light scattering, was 28,000, of the antivenin (pepsin‐digested) 54,000, and of the venom‐antivenin aggregates from 120,000 to 3,100,000, depending on the venom/antivenin ratio.
Diffusion and viscosity measurements on macromolecules in solution
Authors: Rossi C. , Bianchi U. , Magnasco V.
Published: April 2003

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.
Schwermetall‐Komplexe der Polysaccharidformazane
Authors: Mester L.
Published: April 2003

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.
Investigation of polymerization mechanisms by means of molecular weight distributions of reaction products
Authors: Bresler S. E.
Published: April 2003

The study of MWD functions gives insight into the mechanism of polymerization and polycondensation reactions. Especially all kinds of side reactions, by altering the already formed macromolecules, give characteristic changes in the MWD. Some special cases are discussed. For polycondensation products, two types of MWD are found. In the early stages of the reaction before the monomer has been consumed, broad distribution curves of the Flory shape are observed. In the later stages, after the polymer has been heated, quite narrow distributions of the Gaussian type are found. The theoretical explanation involves consideration of scission and macromolecular combination reactions, which result in random interchange of monomer units among macromolecules. For products of addition polymerization of dienes in the presence of a catalytic agent butyllithium, exceedingly narrow distribution functions are observed, the polymer being almost homogeneous. This is the result of simultaneous initiation and further growth of all the chains at the same rate during the entire reaction period without termination. For radical polymerization, sometimes simple unimodal, broad distribution curves are found and the termination constants (recombination and disproportionation rates) can be calculated from the curves. In special cases, however, the distribution functions are complicated and consist of many sharp maxima. It is suggested that secondary reactions of chain scission and macroradical recombination occur, which results in a sharpening of the MWD. Subsequent crosslinking of macromolecules from such sharpened distributions gives doubling, tripling, etc. of average molecular weights. This is the explanation for the polymodal sharpened distribution curves observed.
The effects of shape in streaming birefringence of polymer solutions
Authors: Frisman E. V. , Tsvetkov V. N.
Published: April 2003

In this paper are presented new results obtained during further experimental and theoretical investigations of the form effect in the dynamic double refraction of polymers in solution. The use of the dumbbell theory of W. Kuhn for flexible chains in solution and of the optical modle of an equivalent ellipsoid for the macromolecule, permits the formulation of a theory of flow birefringence which takes account of the form effect for a wide range of shear rates. The conclusions of this theory are compared with new experimental data obtained in a study of polystyrene and p‐tert‐butylphenylmethacrylate in different solvents. In the range of low shear rates and concentrations, the theory is found to be in a good accord with experimental results. On the contrary, the study of the double refraction of several polystyrene fractions in dioxane in a wide range of shear rates and concentrations shows that macromolecules are less deformable in the flow than it follows from the dumbbell theory for ideally flexible chains. A new phenomenon was discovered experimentally—an anomalous dependence of the orientation angle on the shear rate of flow in the range of shear stresses at which the birefringence changes its sign because of compensation of the positive shape effect by the negative intrinsic anisotropy effect. Investigation of the concentration dependence of flow birefringence shows that this dependence is due to two causes—the hydrodynamic and optical interaction of the molecules. The optical interaction is characteristic only for those solutions in which the form effect takes place. A simple theory of concentration dependence of the form effect is proposed which is in good accordance with experimental data.
Polyamides non saturées et leurs copolymères
Authors: Mihail R. , Bittman S. , Rizea A.
Published: April 2003

On sait que, par la copolymérisation d'un polyester non saturé avec un monomère contenant de I'azote dans la molecule, par exemple, le triallylcyanurate, on obtient des produits supérieurs du point de vue de la résistance mécaiiique aux températures éevées. On a escompté l'obtention des mêmes propriété, par la présence des atomes d'azote, non pas dans le composant de liaison entre les chaînes d'un polycondensat, mais dans ces chaînea mbmes. Dans ce but, on a fait une série d'expériences préliminaires, où la chaîne de polyester non saturé a été remplacée par des chatnes depolyamide non saturée. Pour établir les caractéristiques générales de formation et de copolymérisation des polyamides non saturées, on a choisi, parmi le grand nombre de polyamides non saturées qui peuvent étre; considérCes du point de vue thborique, le pol∼éthylhnediamino‐maléate. On a ¨︂ les propriétés de cette polyamide, du point de vue de sa solubilité dans divers sol‐ vants et de la compatibilite avec certains monomhres. On a tenté la copolymérisation de la polyamide non saturee avec du nitrile acrylique et de l'allylamine aussi bien A la température ambiante (20–25°C), qu'à une température plus é1evée (100–120°C), soub pression normale et sous pression 1égbrement plus élevée par initiation avec des peroxydes et par addition d'accé1érateurs pour les durcissements A froid. Parmi les nouvelles propriBtés observées, on peut mentionner la capacite de la polyamide non saturee de servir d'une manibre efficace d'agent de durcissement pour les resines Bpoxy, et I'aptitude du copolymbre avec le nitrile acrylique (allylamine) à être utilisé comme échangeur d'ions.
The alkali‐catalyzed polymerization of caprolactam
Authors: Saunders J.
Published: April 2003

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.
Synthesis of new polymers with inorganic chains of molecules
Authors: Andrianov K. A. , Zhdanov A. A.
Published: April 2003

A synthesis of polyorganosiloxanes is based on attaching organic groups to inorganic silicon‐oxygen chains structurally corresponding to the quartz molecules. The extension of this idea to skeletons composed of silicon, oxygen, and metals, and corresponding structurally to the silicates, led to the synthesis of new polymers containing chains such as
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called polyorganometalosiloxanes. Further development of the idea of attaching organic groups to mineral chains, especially the use of the groups R3SiO—, allowed the inclusion even of elements which do not form stable bonds with carbon. This paper presents some results of our research on the formation of new polymers with mineral chain molecules containing atoms of aluminum, titanium, phosphorus, and oxygen. The reactions leading to the formation of aluminosiloxanes are expressed by the following schematic equations:
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Titanosiloxanes are formed as follows:
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Similarly mixed phosphoaluminosiloxane polymers are prepared:
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Thus carbon and silicon are no longer the only important elements forming polymer chains. Such elements as aluminum, titanium, phosphorus, and many others belonging to the second, third, fourth, and fifth groups of the Periodic System can be used in the synthesis of polymers. The method of organically enveloping inorganic skeletons makes it possible to change the properties of the compounds within wide limits. Silicates, corundum, and inorganic polytitanates are familiar as hard, brittle compounds, insoluble in organic solvents. If now, while preserving the polymer chains typical of these inorganic molecules, we surround them by organic groups, we obtain synthetic polymers with properties markedly different from those of their inorganic analogs. At a certain stage these polymers become soluble in organic solvents, form films typical for organic polymers, and show plasticity. The organic radicals surrounding the inorganic chains increase the flexibility of the molecular chains and confer the elastic properties of typical organic macromolecular compounds on these polymers.
Hydrolysis of methylethoxydisilylmethanes
Authors: Pao‐Jen Wang , Yu‐Jue Zeng , Chih‐Tang Huang , I Lin
Published: April 2003

Hydrolysis of monomers of the type (I) should give polymers with the skeleton SiCSiO, which might possess better properties than siloxanes. The monomers were prepared by the action of methylmagnesium bromide on hexaethoxydisilylmethane. From mono‐ up to pentamethylethoxydisilylmethanes were obtained, the symmetrically substituted and even‐numbered methyl compounds being obtained in preferential yields.

Hydrolysis of these five monomers gave interesting results. The strong tendency of ring formation reduced their functionality and thus gave less chance to form crosslinks. While pentamethylmonoethoxydisilylmethane gave the normal product (II), tetramethyldiethoxydisilylmethane gave a ring dimer (III), which, although closely analogous to cyclosiloxane D4, resisted all attempts at ring opening to give a linear polymer. The trifunctional trimethyl compound gave an oil of the type (IV), consisting of rings connected into a chain by oxygen atoms. Dimethyltetraethoxydisilylmethane, although tetrafunctional, gave, on hydrolysis, a highly crystalline compound with a cage structure (V). Only the pentafunctional monomer, monomethylpentaethoxydisilylmethane, gave an insoluble infusible powder of high stability.

Co‐hydrolysis of the monomers gave fused ring compounds; dimethyltetraethoxydisilylmethane and tetramethyldiethoxydisilylmethane, when hydrolyzed together, gave a compound of formula (VI).
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Einfluss verschiedener strahlen auf stärke
Authors: Samec M. , von Kosovinc I. , Reuschl H.
Published: April 2003

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.
A light scattering study of the interaction of sodium desoxyribonucleate with horse serum albumin
Authors: Sokol F.
Published: April 2003

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.
Cold‐drawing of glass‐like and crystalline polymers
Authors: Lazurkin J. S.
Published: April 2003

Solid polymers—both glass‐like and crystalline—can be cold‐drawn. In addition to studies of the specific aspects of this process in individual cases, as governed by structural features, the development of a theory of cold‐drawing requires an investigation of the general laws of this process. According to the experimental conditions used, cold‐drawing may be carried out either isothermally (at low rates of drawing and with good heat dispersion) or non‐isothermally. A number of specific features of the non‐isothermal process may be explained by a temperature increase in the stressed region; this has in fact been done in published work on this subject. However, the basic features of this phenomenon persist, as has been shown experimentally, in the isothermal cold‐drawing of both glass‐like and crystalline polymers. These features include: (a) the possibility of cold‐drawing, with large residual deformations; (b) the character of the stress—deformation curves; (c) a displacement at the beginning, and a homogeneous or inhomogeneous stretching over the further course of the cold‐drawing (both possibilities being realized in either type of polymer—glass‐like or crystalline); (d) the effect of temperature and the rate of drawing on the initial stress σB. These phenomena must be interpreted in a way which does not involve the assumption of a temperature rise. The values of σB depends on the rate of drawing v, this dependence being expressed by the relation σB = A + B log v, valid for both glass‐like and crystalline polymers. The two types differ only in the value of the constant B, which is lower for crystalline polymers (polyethylene, polyamide, crystalline silicone rubber) than for glass‐like polymers (polyvinyl chloride, amorphous silicone rubber, polymethyl methacrylate, butadiene‐acrylonitrile copolymer, etc.). Crystalline and glass‐like polymers differ in their mechanisms of cold‐drawing. Crystalline polymers, as is well known, undergo recrystallization on deformation; in either type, however, there is a rupture of intermolecular bonds by stresses. Hence follows the kinetic, relaxational character of cold‐drawing. The dependence of σB on the temperature and rate of drawing may be explained on the assumption that the activation energy of the molecular rearrangement is decreased with increasing stresses. Uniform isothermal stretchig is, generally speaking, unstable. The fact that it may be realized in practice, and also the stabilization of the block in non‐uniform drawing, makes it necessary to assume that the mechanical relaxation properties of the polymer change on orientation.
Über vernetzungsgrad un Porosität makromolekularer stoffe
Authors: Mikes J. A.
Published: April 2003

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.
The problem of polymer coacervation
Authors: Broda Andrzej , Chodkowska Maria B.
Published: April 2003

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.
Über Phasentrennung bei kolloiden Lösungen makromolekularer gemische
Authors: Hunyar A. , Wiesner E.
Published: April 2003

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.
Influence de la charge des particules sur la viscosité des sols
Authors: Donnet J. B.
Published: April 2003

Die experimentellen Tatsachen, über welche hier berichtet wird, scheinen zu zeigen, dass das viskosimetrische Verhalten eines Sols geladener Teilchen in zutreffender Weise durch die Theorie (sowohl die von Smoluchowsky als auch die von Booth, übrigens auch nur solange als es sich um die Berechnung von Änderungen und nicht von Absolutwerten handelt) beschrieben wird, sobald man sich mit der Variierung von Parametern zufrieden gibt, die wenig Einfluss auf die Ladung der Teilchen haben; im Gegensatz dazu scheint die Variierung der Ladung, selbst bei Änderungen, die in unserem Fall im Extremtwert einen Übergang von 143 zu 3570 Ladungen pro Teilchen ausmachen, praktisch keinen Einfluss auf die Viskosität zu haben. Ein direkter Beweis für diesen mangelnden Einfluss wird durch die Untersuchung einer Schwärze geliefert, bei welcher die Ladung direkt gemessen wird und die Viskosität konstant blieb, während Q von 810 auf 2260 Elemen tarladungen pro Teilchen anstieg. Dieses Verhalten steht im absoluten Widerspruch zu den Voraussagen der Theorie, die alle erwarten lassen, dass der Relaxationseffekt dem Coulomb'schen Gesetz gehorcht und dass die durch die Ladung bedingte Viskositätszunahme vom Quadrat der Ladung abhängt. Es tritt hier ein sehr wichtiges Problem auf; möglicher Weise ist unser Modell nicht geeignet den Einfluss der Ladung auf die Viskosität wiedergeben zu können, möglicherweise müssen auch die Hypothesen, die als Grundlage für die theoretischen Berechnungen gedient haben, einer Revision unterzogen werden. Da der stark anormale Charakter unserer Ergebnisse auf jeden Fall feststeht, würde es interessant sein, gleichartige Versuche an anderen Modellen auszutühren.
The degradation and denaturation of sodium deoxyribonucleate by γ‐rays
Authors: Peacocke A. R. , Preston B. N.
Published: April 2003

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.