bluuebunny/crossref_metadata_2025 huggingface dataset:
Der nachweis der kettenstruktur von aus p‐kresol und formaldehyd aufgebauten mehrkernverbindungen. III. Herstellung der methyläther der zwei‐ und dreikernverbindung
Authors: Hermann Kämmerer Von , Schweikert Heinz , Haub Hans‐Günter
Published: April 2003

Es wurden Bedingungen gefunden, um die phenolischen Hydroxylgruppen der aus p‐Kresol und Formaldehyd hergestellten Zwei‐ und Dreikernverbindung vollständig zu methylieren. Die Ergebnisse der Permethylierung beweisen die Kettenstruktur und die freien Hydroxylgruppen der Ausgangsverbindungen. Die Struktur der Mono‐ und Dimethyläther sowie des Trimethyläthers der Dreikernverbindung wurde durch Synthese aus einfacheren methoxylgruppenhaltigen Verbindungen bewiesen.
Behaviour of polyelectrolytes in ultracentrifugal molecular weight determinations I. Extrapolation of data
Authors: Erlander Stig R. , Senti F. R.
Published: April 2003

The molecular weight of bovine serum albumin (BSA) was obtained from sedimentation equilibrium in trichloroacetic acid and hydrochloric acid at pH 3.8, in 0.0005 M salt (sodium chloride, sodium trichloroacetate and sodium thiocyanate) plus sulfuric acid at pH 3.2 and in 0.1 M sodium chloride plus hydrochloric acid at pH 1.8. The extrapolated weight‐average molecular weights of BSA were within the range of light‐scattering values reported in the literature. The binding coefficient Γ is approximately equal to the electrostatic charge Z at all pH values studied. The constant value of Γ with a change in Z can be explained by assuming that about 50 carboxylate groups have abnormally low pK values and are paired with the cationic groups of BSA. Binding of salt by the cationic groups occurs only after titration of the carboxylate ions. The extrapolated molecular weight in the absence of salt is not equal to the polymer molecular weight divided by (1 + Z). In addition, it was concluded that the reciprocal of the apparent molecular weight may be plotted against (Ca + Cb)/2 instead of (hCa + Cb)/2 (where h = (BM̄w)a/(BM̄w)b) if haC does not influence Cb appreciably, i.e., when comparatively high rotational speeds are used. The experimental data obtained from the cell bottom indicate that the concentration coefficient obtained from the apparent Z‐average molecular weight is 2(M̄w/M̄z) times as large as that obtained from the apparent weight‐average molecular weight.
Effect of ferric salts on the kinetics of polymerisation of acrylamide initiated by 4‐4′‐azo‐bis‐4‐cyanopentanoic acid
Authors: Cavell E. A. S. , Gilson I. T. , Meeks A. C.
Published: April 2003

The kinetics of the radical polymerisation of acrylamide in the presence of ferric perchlorate and with 4,4′‐azo‐bis‐4‐cyanopentanoic acid as initiator, have been investigated over a range of 15–25°C. Rates of polymerisation at 25°C. have also been measured in the presence of ferric chloride and ferric sulphate. A linear relation exists between the overall rate of reaction and the reciprocal of the concentration of the ferric salt and the rate of polymerisation is proportional to the concentration of the initiator. The pre‐exponential factor and energy of activation of the initiation reaction have been calculated from the rates of polymerisation determined and the values found were 5.64.1012/sec. and 26.05 kcal./mole respectively.
Poly‐N‐methacrylyl cysteine
Authors: Ida Tadao , Noda Kazuo , Takahashi Shoji , Utsumi Isamu
Published: April 2003

The synthesis and the properties of poly‐N‐methacrylyl cysteine have been studied. Poly‐N‐methacrylyl cysteine was prepared from S‐thiophenyl‐N‐methacrylyl cysteine, S‐benzyl‐N‐methacrylyl cysteine or N,N′‐bisymethacrylyl cystine, by polymerizing them in the presence of a radical catalyst and reducing the respective polymers formed. Copolymers of N‐methacrylyl cysteine and vinyl compounds were also synthesized. These polymers were converted by the oxidation with iodine to polymers with disulfide crosslinking and reacted with halogen compounds or some disulfide compounds. They reacted, like low molecular mercaptans, also with metallic ions and carbonyl compounds.
Über die fällung kurzkettiger polystyrole
Authors: Breitenbach Von J. W. , Kuchner K.
Published: April 2003

Niedermolekulare Polystyrole wurden durch spontane thermische Polymerisation von Styrol in Gegenwart von Tetrachlorkohlenstoff dargestellt. Aus der Reaktionsmischung wurde das Polymere einerseits durch Abdampfen des Styrols und Tetrachlorkohlenstoffs im Vakuum, andererseits durch Ausfällung mit Methanol gewonnen. Die durch die Ausfällungen hervorgerufenen Änderungen in Gewicht, Chlorgehalt und Viskositätszahl des Polymeren wurden bestimmt. Es wird gezeigt, welche Schlüsse aus den Eigenschaften des gefällten Polymeren auf diejenigen des ursprünglichen Polymeren möglich sind.
Zur technik der fraktionierung in kolonnen mit temperaturgradienten
Authors: Meyerhoff Von G. , Romatowski J.
Published: April 2003

Es wird eine Weiterentwicklung der „chromatographischen”︁ FäLlungsfraktioniermethode beschrieben. Die Kolonne besteht ganz aus Metall, wodurch gute Wärmeüibergänge zur Herstellung des Temperaturgradienten langs der Kolonnenachse ermöglicht werden. Die Durchstromungsgeschwindigkeit läßt sich durch ein Nadelventil gut regulieren. Zur Herstellung eines variablen Lösungsmittel‐Fällungsmittelgemisches wird eine neue, besonders einfache und zuverlässige Vorrichtung beschrieben. Bei dieser kann durch eine bewegliche Trennwand das Verhältnis der beiden Komponenten als Funktion des durchgeflossenen Volumens beliebig eingestellt werden.

Die optimale Kolonnendimensionierung im Hinblick auf Fraktionierungen von Polymeren sehr hoher Molekulargewichte (M > 106) und sehr breiter Verteilungen wird diskutiert. Beispiele füxsr auf diese Weise erhaltene Verteilungskurven von Polystyrolen werden angegeben.
Synthese linearer und cyclischer Oligoamide der ε‐Aminocapronsäure mit aktiven Derivaten der phosphorigen Säure und der Phosphorsäure1. Lineare und cyclische Oligomere. XI
Authors: Rothe Von Manfred , Rothe Ilse , Brünig Helmut , Hossbach Rosemarie , Schwenke Klaus‐Dieter
Published: April 2003

Es wird eine neue Methode zur Synthese der polymerhomologen cyclischen Oligoamide der ε‐Aminocapronsäure vom 14‐gliedrigen Cyclo‐diamid bis zum 42‐gliedrigen Cyclohexaamid in hohen Ausbeuten und in Gramm‐Mengen beschrieben. Sie erfolgt durch direkte Cyclisierung der linearen Oligoamide mit aktiven Derivaten der phosphorigen Säure (Pyrophosphite und Phosphorigsäure‐chloride) und der Phosphorsäure (Polyphosphorsäureester) nach dem ZIEGLERschen Verdünnungsprinzip. Die Vorteile vor den bisher verwendeten Ringschlußmethoden werden aufgezeigt.

Das gleiche Verfahren stellt auch einen besonders einfachen und ergiebigen Weg zur Gewinnung molekulareinheitlicher linearer Oligoamide durch Verknüpfung von Carbobenzoxy‐oligoamiden mit Oligoamid‐benzylestern und anschließender hydrogenolytischer Abspaltung der Schutzgruppen dar.
The calculation of the unperturbed dimensions of cis‐1,4 polybutadiene
Authors: Allegra G. , Flisi U. , Crespi G.
Published: April 2003

Since no previous theoretical calculation of the unperturbed dimensions of cis‐1,4 polybutadiene took into account the particular nature of the energy barriers to the rotation around single (CC) bonds adjacent to double bonds, a new matrix calculation has been carried out, the results being given as a function of two energy parameters, ΔE1 and ΔE2. They show that the best agreement between evaluated and experimental data occurs for values of the above parameters near to those obtained for simpler molecules showing structural analogies with the polymer under consideration; in particular, the unusual positive value of the variation of 〈r〉 with temperature (20° ≤ T ≤ 60°C.), obtained by stress‐temperature measurements, is in good agreement with the calculated figures.
The determination of the diethylene glycol incorporated in poly(ethylene terephthalate)
Authors: Janssen R. , Ruysschaert H. , Vroom R.
Published: April 2003

A method for determining the diethylene glycol contents in poly(ethylene terephthalate) has been worked out. The method consists in a transesterification under pressure with an excess of ethanol. The reaction mixture is subjected to a gas chromatographic analysis.
Die geschwindigkeitskonstanten für die dissoziation und die assoziation des polystyrolnatriums in tetrahydrofuran (THF)
Authors: Löhr Von G. , Schulz G. V.
Published: April 2003

Aus der Molekulargewichtsverteilung anionischer Polymerisate ergeben sich unter der Voraussetzung, daß die Dissoziationskonstante des Polystyrolnatriums in THF KD ≈ 10−7 Mol/l ist, für die Geschwindigkeitskonstante der Dissoziation kd = 0,8.102 sec−1 und der Assoziation zum Ionenpaar ka ≈ 109 l Mol−1sec−1.
Copolymers of tert.‐butyl vinyl ether with maleic or citraconic anhydride
Authors: Kern R. J.
Published: April 2003

Copolymers of tert‐butyl vinyl ether and maleic or citraconic anhydride undergo acidcatalyzed intramolecular rearrangement to poly(carboxy‐lactones). The same rearrangement easily occurs thermally with evolution of isobutylene. At higher temperatures above 200°C. carbon dioxide is also given off. When heated, shaped articles of these copolymers soften and then expand markedly as rigid foams develop. Citraconic derivatives are thermally more stable than their maleic analogs.
Asymmetric‐selection polymerization of d,l‐propylene oxide by (FeCl3‐propylene oxide) complex — H2O catalyst containing d‐bornyl ethyl ether
Authors: Furukawa Junji , Akutsu Seiichi , Sàegusa Takeo
Published: April 2003

Racemic propylene oxide (d,l‐PO) was polymerized by the catalyst which was the reaction mixture from the partial hydrolysis of the FeCl3–PO complex carried out in the presence of d‐bornyl ethyl ether (d‐BEE). The unreacted monomer recovered from the polymerization system was shown to be optically active, the concentration of l‐monomer preponderated over that of d‐monomer. The polymer product, however, was of no optical activity although it contained a considerable amount of isotactic crystalline part. In another separate experiment, d,l‐PO was added to the asymm. catalyst system at a lower temperature where no polymerization occurred and the monomer was recovered by distillation under reduced pressure at —20°C. Triethylamine was added to the residue and volatile material was distilled again. By optical activity measurement, the PO fraction of the first distillate (before amine addition) was shown to be rich in l‐monomer and that of the second distillate (after amine addition) was rich in d‐monomer. Thus it has been shown that d‐monomer is predominant over l‐monomer both in adsorption and in polymerization. A kinetic consideration showed that the d/l ratio in the adsorbed monomer agreed with that of the consumption rate in polymerization. These findings lead us to the conclusion that the propagation reaction of polymerization consists of two steps, adsorption (coordination) and ring opening steps, and that the unequality in polymerization rate between d‐ and l‐monomers is controlled chiefly by the adsorption step. The formation of crystalline polymer of no optical activity from the asymm. consumption of monomer is discussed.
Synthesis of virtually monodisperse linear and tetrachain polymers with „idealized”︁ structures by use of a novel initiator, α‐phenylethylpotassium
Authors: Yen Shiao‐Ping Siao
Published: April 2003

A virtually monodisperse polystyrene (M̄w/M̄n = 1.06) was prepared by use of a novel initiator, α‐phenylethylpotassium. The chain structure of this polystyrene when terminated with a proton contained no foreign functional end‐groups, except hydrogen atoms at both ends.
magnified image
The chain structure was, therefore, “ideal” since the initiating groups was actually one segment of the repeating sequence. A virtually monodisperse polystyrene tetrafunctional star molecule (M̄w/M̄n = 1.05) also was made by coupling of the polystyrylpotassium with 1,2,4,5‐tetrachloromethylbenzene. This reaction proceeded smoothly to completion as evidence by stoichiometry, ultracentrifuge, and fractionation data.
Polymerisation of methyl methacrylate by organometallic compounds. I. Kinetic studies
Authors: Allen P. E. M. , Moody A. G.
Published: April 2003

The kinetics of the polymerisation of methyl methacrylate by GRIGNARD reagents are examined. The optimum temperature effect is shown to be due to reactions, which, during the first few minutes of the polymerisation, determine the concentration of active macromolecular chains. These reactions are also responsible for the complex dependence of rate of polymerisation on initial monomer concentration and the transient colour which appears when the reagents are mixed. kp is of the order of 10−21./mole · s. and the energy of activation is small.

Preliminary experiments with triethylaluminium polymerisations are reported. These also show an optimum temperature effect.
Kinetik der polymerisation von trioxan in gegenwart von wasser
Authors: Kučera Von Miloslav , Spousta Eduard
Published: April 2003

Aus den Werten der Geschwindigkeitskonstante des geschwindigkeitsbestimmenden Prozesses der mit ∼︁Si⊕HSO4⊖ initiierten Polymerisation einer Trioxanschmelze, der Geschwindigkeit der Formaldehydentstehung während der Induktionsperiode und der Leitfähigkeit des Systems Trioxan/Initiator/Wasser wurde abgeleitet, daß die Polymerisation über die Ionenpaare ∼︁C⊕HSO4⊖ verläuft. Wasser solvatisiert dieses Ionenpaar, was die Übertragungsreaktionen erleichtert, aber auch beide Ionen “freimacht”. In Gegenwart von kleinen Wassermengen wuchsen die Polymerisationsgeschwindigkeit und die Geschwindigkeit der Formaldehydentstehung mit der Wasserkonzentration. Die Gegenwart von größeren Wassermengen bringt wieder eine Verlangsamung der Polymerisation und eine Verlängerung der Induktionsperiode. Das wird wahrscheinlich durch den erschwerten Zutritt der Trioxanmoleküle zu den durch Wasser stark solvatisierten aktiven Zentren verursacht.

Wasser wirkt in niedrigen Konzentrationen als Cokatalysator. Man darf erwarten, daß Trioxan in einem von Wasser, bzw. von Verbindungen mit hoher Dielektrizitätskonstante und mit großer Solvatationsfähigkeit ganz freien Milieu nicht polymerisieren wird.
Blockierung der endgruppen von polyformaldehyd. I. Eine verbesserte methode zur bestimmung des anteils von blockierten endgruppen
Authors: Mejzlík Von Jiří , Pác Jiří
Published: April 2003

Die von KERN und CHERDRON vorgeschlagene Methode zur Bestimmung des Anteils an blockierten Endgruppen in Polyformaldehyd läßt sich verbessern, wenn man dem Polymeren geeignete nucleophile oder elektrophile Reagenzien zusetzt, welche die Depolymerisation von den Hydroxylendgruppen aus katalysieren (z. B. 1% Kaliumchlorid, 0,5% Natriumacetat oder 4% Stearinsäure). Die Reaktionszeiten werden dadurch wesentlich kürzer und die Meßergebnisse verläßlicher. Mit dieser modifizierten Methode kann der Anteil an Makromolekülen bestimmt werden, der durch Ester‐ oder Äthergruppen blokkiert ist; gegebenenfalls kann sie auch zur Bestimmung der Stabilität von Copolymeren des Trioxans herangezogen werden.
Polymer chain end accessibility in bimolecular reactions
Authors: North A. M.
Published: April 2003

In order to explain the observed rates of diffusion‐controlled macroradical bimolecular reactions, the probability of finding a polymer chain end less than a critical distance from the outer limits of the whole coiled flexible chain has been calculated. The probability that two active centres on the surfaces of the two rotating spheres come into proximity during an inelastic collision has also been calculated. When these probabilities are combined with the rate constant for diffusion‐controlled approach of macroreactants, agreement with experimental observations is found only for the soft‐sphere model.
On the polymerization of formaldehyde in liquid state. I. Gamma ray‐initiated polymerization of the monomer in solution
Authors: Nakashio Seizo , Ueda Mitsuo , Takahashi Kei
Published: April 2003

This paper presents a more detailed discussion on the kinetics of formaldehyde polymerization under gamma‐irradiation than the previous paper2. Polymerization took place in toluene and ethyl bromide and within the range of −50°∼−80°C.

The overall reaction is approximately third‐order with respect to the monomer. The average molecular weight of the polyoxymethylene obtained is little dependent on the initial concentration of the monomer and on dose rate. The reaction is approximately first order with respect to dose rate. It is believed from the facts obtained here that the polymerization, in which the transfer process of growing chain to monomer is mainly responsible for governing the molecular weight, should proceed predominantly by an ionic mechanism.

A study of the influence of various additives upon the polymerization shows the following results. These additives are classified in four groups with respect to their qualities, the first group having influence only upon the polymerization rate (e.g., diphenylpicrylhydrazyl), the second only upon the molecular weight (water), the third upon both of these factors (methyl formate, methyl acetate, ethyl acetoacetate, polystyrene powder, and tetrahydrofuran), and the last having no influence upon both of these factors (oxygen, carbon monoxide, nitrobenzene, and naphthalene).

The apparent activation energy is estimated to be 4.15 kcal/mole from rate of polymerization, −3.50 kcal./mole from average degree of polymerization.
Die bestimmung der molekularen kettenstruktur von vinylidenchlorid‐vinylchlorid‐copolymeren aus dem ultrarot‐spektrum
Authors: Germar Von H.
Published: April 2003

In der vorliegenden Arbeit wird die Kettenstruktur von Vinylidenchlorid (VDC)‐Vinylchlorid (VC)‐Copolymeren aus deren Ultrarot‐Spektren bestimmt. Die Monomereinheiten können in den drei Anordnungen: VDC‐VDC, VDC‐VC und VC‐VC vorkommen, wobei als Verknüpfungsstelle zweier Monomereinheiten jeweils eine Methylengruppe anzusehen ist. Die UR‐Banden der Scherenschwingung dieser drei unterschiedlichen Arten von Methylengruppen erscheinen bei verschiedenen Wellenzahlen. Aus der quantitativen Analyse dieses Bandensystems wird die Häufigkeit der drei möglichen Schritte bestimmt. Sie wird mit der aus der bekannten Copolymerisationsgleichung berechneten Verteilung verglichen. Mit den Parametern r1 = 3,2 und r2 = 0,2 ergibt sich gute Übereinstimmung zwischen Rechnung und experimentellen Werten. Außerdem wird gezeigt, wie man aus den gemessenen Häufigkeiten die Sequenzlängenverteilung erhält. Sie wird für drei Copolymere verschiedener Zusammensetzung berechnet und dargestellt.
Cohesive‐energy‐densities of high polymers. Part VI. C.E.D. of polyvinyl esters
Authors: Mangaraj D. , Patra S. , Roy P. C. , Bhatnagar S. K.
Published: April 2003

The solubility parameters (δ) of polyvinyl acetate and polyvinyl propionate were estimated by their swelling and solution viscosity measurements in a series of alkyl esters and were compared with the δ‐values calculated from SMALL's result. The δ‐values of these polymers are comparable with the δ‐values of their structural equivalents, whereas in a homologous series δ decrease with increase in the volume of the alcoholic residue.
Configuration of vinyl polymers from high resolution nuclear magnetic resonance spectra. II. Polypropylene
Authors: Tincher W. C.
Published: April 2003

High resolution NMR‐spectra of polypropylene, poly(3,3,3‐d3‐propylene), and poly(1,1‐d2‐propylene) have been obtained and analyzed. Although the methinyl proton spectrum is not influenced by the stereochemical configuration, differences do appear in the methylene proton spectrum which can be related to tacticity. By comparison of calculate methylene proton spectra assuming different ratios of isotactic and syndiotactic diads with the observed spectra, it is possible to obtain information about the tacticity of polypropylene samples. This method of obtaining information about polymer configuration should be generally useful for polymers which have complex NMR‐spectra.
Lichtstreuungs‐ und viskositätsmessungen über den abbau von polymeren in lösung unter dem einfluß von 60Co‐γ‐strahlen
Authors: Ikada Von Yoshito , Schnabel Wolfram
Published: April 2003

Es wurden Lichtstreuungs‐ und Viskositätsmessungen an Polymeren durchgeführt, die in Lösungen unterhalb der kritischen Konzentration γ‐Strahlung ausgesetzt worden waren. Hierdurch ließ sich entscheiden, ob die Polymeren in verdünnter Lösung intramolekular vernetzen oder hauptsächlich in der Hauptkette abgebaut werden. In allen untersuchten Fällen wurde der Abbau nachgewiesen. Polyvinylpyrrolidon in Methanol besitzt keine nachweisbare Verzweigung, wenn es unterhalb der kritischen Konzentration bestrahlt worden ist. Oberhalb der kritischen Konzentration nimmt die Verzweigung mit der Dosis nach einer von KILB angegebenen Beziehung zu. Der Verzweigungsgrad eines ursprünglich stark verzweigten Polyvinylacetats nimmt bei der Bestrahlung in verdünnter Acetonlösung sogar ab. Polystyrol wird in Benzol bei kleiner Konzentration ebenfalls praktisch nicht verzweigt. Ähnliches gilt für Polydimethylsiloxan in Benzol. Die Ergebnisse werden nach der Theorie von HENGLEIN über Abbau und Vernetzung von Polymeren in organischen Lösungsmitteln diskutiert.
Solvatation von makromolekeln in binären lösungsmitteln. III. Die anzahlen der solvatmolekeln von polystyrol im lösungsmittelgemisch benzol/methyläthylketon
Authors: Lange Von H.
Published: April 2003

Als Anwendungsbeispiel für eine vor kurzem abgeleitete Methode zur Bestimmung der Anzahlen von Solvatmolekeln makromolekularer Substanzen in ein‐ und zweikomponentigen Lösungsmitteln wurden die Anzahlen der Solvatmolekeln einer Monomereinheit von Polystyrol im Lösungsmittelgemisch Benzol/Methyläthylketon (MÄK) als Funktion der Temperatur und der Lösungsmittelzusammensetzung näherungsweise bestimmt. Dabei ergab sich, daß die Anzahlen der Solvatmolekeln zwischen 20 und 70°C bei allen Lösungsmittelzusammensetzungen einschließlich der beiden Grenzfälle, bei denen das Lösungsmittel jeweils nur aus einer Komponente besteht, nicht merklich von der Temperatur abhängen. Außerdem wurde gefunden, daß die Polystyrolmolekeln durch die Komponente Benzol bevorzugt solvatisiert werden. Im Vergleich zu der Anzahl der Solvatmolekeln einer Monomereinheit von Polystyrol im reinen Benzol, die bereits aus früheren Messungen zu 3,1 ± 0,4 ermittelt wurde, ergab sich für die entsprechende Anzahl im reinen Methyläthylketon trotz etwa gleicher Molekelgröße nur 0,7 ± 0,2.
Vinyl polymerization. 93. Polar effects in radical polymerization of p‐substituted styrenes
Authors: Imoto Minoru , Kinoshita Masayoshi , Nishigaki Masahiko
Published: April 2003

The radical polymerization of styrene and of the p‐substituted styrenes p‐methoxy‐, p‐methyl‐, p‐fluoro‐, p‐chloro‐, p‐bromo‐, and p‐cyanostyrene, was kinetically studied. The styrenes with more electron‐attracting substituents show a greater overall rate of polymerization. At 30,0°C., the individual rate constants of propagation (kp) and termination (kt) were determined by a rotating sector and by usual inhibitor method using diphenylpicrylhydrazyl (DPPH) or p‐benzoquinone. It was found that the following HAMMETT relationship is established in the homopolymerization of p‐substituted styrenes:

where σ is the HAMMETT constant, and ρ′ is a reaction constant which was calculated as +0.6. This relation is interpreted from a participation of ionic structures in the transition state of the propagation reaction. For confirmation, MULLIKEN's electronegativity of the p‐substituted styrene and the p‐substituted benzyl radical was calculated by simple LCAO MO method. The relationship between the rate constants of termination, kt, and the σ‐values is expressed by two lines, crossing at p‐fluorostyrene which is at the maximum point. These two lines are explained by two ways; one is the diffusion controlled termination and the other is the recombination of the two polarized radical ends.
Zur kinetik der anionischen polymerisation von styrol in tetrahydropyran. II.
Authors: Barnikol Von W. K. R. , Schulz G. V.
Published: April 2003

Die durch Na‐Naphthalin angeregte Polymerisation des Styrols verläuft in Tetrahydropyran (THP) nach dem gleichen Mechanismus wie in Tetrahydrofuran (THF), jedoch mit niedrigeren Werten für die entsprechneden Konstanten.
On the pressure and concentration dependence of the sedimentation coefficient
Authors: Cantow Manfred J. R. , Porter Roger S. , Johnson Julian F.
Published: April 2003

In the ultracentrifugation of solutions in organic solvents the sedimentation coefficient has to be corrected for two effects: the increasing dilution of the solution due to the sector shape of the centrifuge cell and the increasing density and viscosity of the solvent caused by the effective field of gravity. The corrections can amount to 10–30% of the measured value. A new graphical method of correcting for both effects without the need for any additional data is described. This technique in combination with established procedure also allows calculation of an average molecular weight of the solute.
Die Ultrazentrifuge als Kriterium für molekulare Einheitlichkeit. Grenze des Auflösungsvermögens und der Empfindlichkeit
Authors: Bodmann Von O. , Kranz D. , Mutzbauer H.
Published: April 2003

Die Gradientenkurve einer zusammengesetzten, in der Ultrazentrifuge sedimentierenden Grenzschicht von zwei Komponenten wird auf Grund einfacher Voraussetzungen berechnet, welche praktisch z. B. bei einer Mischung der α‐Amylasen aus Bacillus subtilis und Humanspeichel zutreffen. Dabei wird ein Ausdruck für das Auflösevermögen der Sedimentation in Einheiten molekularer und apparativ vorgegebener Konstanten abgeleitet:

Diskontinuität der Verteilung der Sedimentationskoeffizienten vorausgesetzt, ist danach für die Ausbildung getrennter Maxima in der Gradientenkurve ein Mindestunterschied der Sedimentationskoeffizienten erforderlich, welcher sich nach dieser Formel mit dem Wert A > 1 abschätzen läßt.

Die rechnerische Behandlung des Modells zeigt ferner, daß bei Mengengleichheit der beiden Komponenten von A > 0,5 an bereits durch eine Analyse der Kurvenform sichtbar gemacht werden kann, daß die Modellsubstanz nicht einheitlich ist. Die Anwendung dieser Methode setzt allerdings konzentrationsunabhängige Sedimentation und Diffusion voraus.

Das empfindlichste Kriterium für eine einheitliche Sedimentation beruht auf dem Vergleich des scheinbaren Diffusionskoeffizienten, der aus der sedimentierenden Grenzschicht ermittelt wird, mit dem wirklichen Diffusionskoeffizienten, der auf unabhängigem Wege zusätzlich bestimmt werden muß.

Dieses Kriterium kann auch dort herangezogen werden, wo lineare Konzentrationsabhängigkeit des Sedimentationskoeffizienten vorliegt, wenn der störende Einfluß der Selbstschärfung der Grenzschicht nach FUJITA berücksichtigt wird. Bei gewöhnlicher experimenteller Genauigkeit beginnt die Empfindlichkeit des letzten Verfahrens gegenüber uneinheitlicher Sedimentation, wenn der Abstand der beiden Sedimentationskoeffizienten einen Wert überschreitet, der durch A > 0,25 abgegrenzt werden kann.
Ions, ion‐pairs, and their agglomerates
Authors: Szwarc M.
Published: April 2003

The concepts of ion‐pairs, solvent separated ion‐pairs, and of higher agglomerates is reviewed. The conditions under wich these concepts are justified are outlined. Relations between conductance and the ion association is examined. The effect of solvents upon the association, the mobility of ions, their degree of solvation, etc. are discussed.
Factors influencing essential fiber properties
Authors: Atlas S. M. , Mark H.
Published: April 2003

The fundamentals of macromolecules are presented with respect to fiber forming materials. The physical and chemical methods which enable one to alter or modify a given fiber are discussed. The possibilities for the different groups of fiber‐types are presented in detail.
Poly‐(pearfluoralkylen)‐benzimidazole
Authors: Burmeister Von D. , Sander M. , Bergert K. H.
Published: April 2003

Bei der Herstellung von Poly‐(perfluoralkylen)‐benzimidazolen tritt neben HF vor allem CO2 als Zersetzungsprodukt auf. Die gebildeten, fluorhaltigen Benzimidazole sind oberhalb 250°C unbeständig, wie an Hand von reinen Modellsubstanzen gezeigt wurde. Der Abbaumechanismus ist so verwickelt, daß er nicht auf einfache Weise geklärt werden kann.
Polychelatsiloxane 2. Mitt.: Polykondensation von siliciumfunktionellen metallchelaten
Authors: Hofer Von A. , Kuckertz H. , Sander M.
Published: April 2003

Durch Addition von (CH3)2SiHCl und CH3SiHCl2 an die Beryllium‐ und Aluminium‐chelate des 4,4‐Diacetylbuten‐1 (Allylacetylaceton) ließen sich die entsprechenden siliciumfunktionellen Silylpropylchelate in hoher Reinheit und Ausbeute herstellen. Hydrolyse und Polykondensation führten im Falle des bifunktionellen Be‐Chelates zu linearen Polychelat‐siloxanen, die bei etwa 70°C erweichen, aber erst oberhalb 200°C schmelzen. Hydrolytische Polykondensation von tri‐, tetra‐ und hexafunktionellen Chlorsilylchelaten ergab vernetzte, pulverige Polymere; gleichzeitig trat in gewissem Umfang hydrolytische Spaltung der Metallbindung ein.
A model of the chain conformation of an isotactic vinyl polymer, having optically active side groups
Authors: Allegra G. , Corradini P. , Ganis P.
Published: April 2003

In this paper a mathematical treatment is developed for the developed for the calculation of the average percentage of right‐handed and left‐handed conformations of isotactic polymer chains having asymmetric side groups, all with the same optical sign, in unperturbed solution. This method derives the partition function of the infinite chains by a matrix formulation, allowing for neighbor interactions according to the ISING model; it leads to results which are in qualitative agreement with the experimental values of the optical rotation exhibited by polymer solutions at various temperatures.
Crystal structure of hexagonal polythiomethylene
Authors: Carazzolo Gianalvise , Valle Giovanni
Published: April 2003

The crystal structure of hexagonal polythiomethylene is described. It has a hexagonal unit cell with a = 5.07 Å. and c = 36.52 Å. The polymer chains are helicoidal with the axis of the helix parallel to c. In the unit cell are comprised 17 CH2Sunits and 9 turns of the helix.
Synthesis of optically active polymers by asymmetric catalysts. IV. Dialkylzinc – alcohol system as catalyst for asymmetric‐selective polymerization of propylene oxide
Authors: Inoue Shohei , Yokota Yoshihisa , Yoshida Norimasa , Tsuruta Teiji
Published: April 2003

The system diethylzinc/optically active alcohol was examined as catalyst for asymmetric‐selective polymerization of propylene oxide. Optically active alcohols with rigid structure are effective for the asymmetric selection. D(–)‐1‐Methoxypropanol‐2 as well as poly(D‐propylene oxide) of low molecular weight with hydroxyl end groups select L(–)‐propylene oxide. „Catalyst control”︁ mechanism of the stereoselection in the polymerization is suggested on this and other bases.
A critical consideration of the molecular weight distribution of narrow‐distribution polymers
Authors: Ueda Minoru
Published: April 2003

Numerical fractional solution was applied to a narrow‐distribution polymer having SCHULZ‐ZIMM type distribution (xn = 2000, xw/xn = 1.05) by using a solubility equation based on FLORY‐HUGGINS' theory. Fractions obtained by a series of ten trials overlap extensively with each other and have xw/xn values comparable to the initially given one. Application of the usual SCHULZ method to the data obtained gave a distribution far narrower than the initially given one especially in the lower molecular weight region. On the other hand, a reasonable distribution was obtained when the fractionation data were analyzed in terms of the new method proposed by HOMMA et al. This seems to justify the proposal of HOMMA et al. and their results obtained by sedimentation velocity method.
Synthetische lineare polymere XV.: Die abhängigkeit einiger spezifischer eigenschaften polymerhomologer oligomerverbindungen von der molekülgröße
Authors: Géczy Von I.
Published: April 2003

Zwischen dem Molekulargewicht einzelner Glieder von polymerhomologen Reihen und solchen spezifischen Eigenschaften, welche von additiven Größen abgeleitet werden können, ist folgender Zusammenhang gültig: \documentclass{article}\pagestyle{empty}\begin{document}$\Phi _{{\rm sp}} = \frac{a} {m} + b$\end{document}, wobei Φsp irgendeine spezifische Eigenschaft, \documentclass{article}\pagestyle{empty}\begin{document}${z}.{B}.\frac{{\gamma ^{1/4} }}{d}$\end{document} = spezifisches Parachor, \documentclass{article}\pagestyle{empty}\begin{document}$- \frac{{\gamma ^{1/4} }} {d}{\rm log (}n{ - 1)}$\end{document} = spezifisches Refrachor, \documentclass{article}\pagestyle{empty}\begin{document}$\frac{x} {d}$\end{document} = spezifische magnetische Suszeptibilität, \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{2,9\ {\rm log}\ {\rm log }\eta { }}} {{\rm d}}$\end{document} = spezifische Viskositätszahl, \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{v^{1/3} }} {d}$\end{document} = spezifische Schallgeschwindigkeit, n = Brechungsindex, \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{n^2 + 1}} {{n^2 + 2}} \cdot \frac{1} {d}$\end{document} = spezifische Refraktion und M das Molekulargewicht ist. a und b sind Konstanten, deren Wert experimentell oder mit Hilfe der entsprechenden Inkremente ermittelt werden können. Der Wert der Konstante b kann zur Errechnung der Inkrementwerte der Atome des Grundmols verwendet werden. Einige dieser spezifischen Größen sind ferner zu Molekulargewichtsbestimmungen von Molekeln in der Größenordnung von 103−105 geeignet, z. B. von polymeren Weichmachern und synthetischen Fasern, hauptsächlich von Polyamiden und Polyestern.
Die anwendung der eisenrhodanidmethode zur quantitativen bestimmung des peroxidgehaltes in strahlenoxydiertem polyvinylchlorid
Authors: Zeppenfeld Von G.
Published: April 2003

Die von YOUNG, VOGT und NIEUWLAND erstmals beschriebene Eisenrhodanidmethode wurde für die Bestimmung von aktivem Sauerstoff in Polyvinylchlorid (PVC) modifiziert.

Das Prinzip der Methode besteht in der Reduktion des Peroxids in Gegenwart von Schwefelsäure durch Eisen(II)‐ionen und dem kolorimetrischen Nachweis des gebildeten Eisen(III) als Rhodanidkomplex. Die Methode gestattet den quantitativen Nachweis von Peroxiden auch in Anwesenheit ungesättigter Verbindungen. Mit einer unteren Nachweisgrenze von 1·10−6 Mol/l ist sie etwa so empfindlich wie die bekannte Methylenblaumethode. Ihr Vorteil gegenüber der letztgenannten besteht in der Verwendung stabiler käuflicher Analysensubstanzen.

Zur Bestimmung des aktiven Sauerstoffs in PVC wird eine etwa 1‐proz. Lösung des Materials in Tetrahydrofuran mit einer Mischung, bestehend aus Benzol und einer Lösung der anorganischen Salze in Methanol, versetzt. Mit Hilfe dieser Methode wurde in strahlenoxydiertem PVC Hydroperoxid nachgewiesen.
Condensation polymerization of N‐dithiocarbonyl alkoxycarbonyl‐amino acids. Part I. Synthesis and condensation polymerization of N‐dithiocarbonyl ethoxycarbonyl‐amino acids
Authors: Higashimura T. , Kato H. , Suzuoki K. , Okamura S.
Published: April 2003

N‐dithiocarbonyl ethoxycarbonyl‐amino acids (III),
magnified image
were synthesized in crystalline form from various amino acids by the addition of ethyl chlorocarbonate to dithiocarbamic acid salt obtained from amino acid and CS2 at low temperature. When the reaction was performed above room temperature, polypeptides could directly be obtained without getting III.

Compounds such as III were synthesized from glycine, DL‐α‐alanine, DL‐valine, DL‐methionine, L‐leucine, glycylglycine, β‐alanine, γ‐amino‐n‐butyric acid and ε‐amino‐n‐caproic acid in this paper. III were polymerized to polypeptides in high yields in the presence of a basic catalyst or by heating; acid inhibited the polymerization of III.
Condensation polymerization of N‐dithiocarbonyl alkoxycarbonyl‐amino acids. Part. II. Condensation polymerization of N‐dithiocarbonyl ethoxycarbonyl‐DL‐α‐alanine in organic solvents
Authors: Higashimura T. , Suzuoki K. , Kato H. , Okamura S.
Published: April 2003

The effect of polymerization conditions on the rate of polymerization and molecular weights of resulting polymer was studied with N‐dithiocarbonyl ethoxycarbonyl‐DL‐α‐alanine.
magnified image
in toluenc, dioxane, nitrobenzene and methyl isobutyl ketone.

In dioxane, which is a very suitable solvent to obtain high molecular weight polymers, the molecular weight of resulting polymer decreased with increasing monomer concentration. Basic substances accelerated the rate of polymerization, but decreased the molecular weight of resulting polymer. Water accelerated the rate of polymerization and the decrease of molecular weight was not so large.
Polybenzyl polymers I. The effect of monomer structure on polymer properties
Authors: Overhults W. C. , Ketley A. D.
Published: April 2003

A systematic study has been made of the effect of methyl substitution in the aromatic ring on the FRIEDEL‐CRAFTS polycondensation of p‐dichloromethylbenzene and its derivatives with benzene derivatives. When the total number of methyl groups on the monomer and comonomer is four or greater, highly crystalline, low molecular weight products are formed. When the number of methyl substituents is less than four, rapid polymerization occurs to give amorphous, cross‐linked materials. By careful control of reaction conditions, however, the latter reactions can be stopped before cross‐linking takes place and relatively high‐molecular weight, non‐cross‐linked polymers can be isolated.
Polymerization of 2‐vinyl‐1,3‐dioxolane
Authors: Tada Koichi , Saegusa Takeo , Furukawa Junji
Published: April 2003

When 2‐vinyl‐1,3‐dioxolane was treated at low temperature (−78 or −130°C.) with cationic catalysts, oily or semi‐solid polymer was produced. The result of alkaline hydrolysis showed that the polymeric product contained ester units whose amount was about 2 to 15 mole‐% of the total units. The remaining part of the polymer consisted of units containing the dioxolane ring. In the alkaline alcoholysis of the polymer with ethanol ethyl δ‐hydroxyvalerate was formed. These findings indicate that in the low temperature cationic polymerization of 2‐vinyl‐1,3‐dioxolane the ester unit, O(CH2)4CO, is formed in addition to the unit of vinyl polymerization. A mechanism for the formation of the ester unit has been proposed, in which the process of hydride‐shift is followed by ring‐opening of the resulting carbonium ion species of dioxolane.
Self‐polymerization of aromatic dinitrile N‐oxide
Authors: Imai Yoshio , Akiyama Masayasu , Uno Keikichi , Iwakura Yoshio
Published: April 2003

Self‐polymerization based on 1,3‐dipolar cycloaddition of isophthalonitrile N‐oxide and terephthalonitrile N‐oxide was attempted to prepare polyfuroxans. The polymers with inherent viscosity up to 0.15 were obtained in approximately quantitative yield. Polyfuroxans were only soluble in concentrated sulfuric acid, and indicated some degree of crystallinity.
The cationic polymerization of epoxides determination of polymer structures by NMR spectroscopy
Authors: Haubenstock H. , Naegele W.
Published: April 2003

Although it is well established that the low temperature cationic polymerization of 3‐methylbutene‐1 and its homologs involves extensive rearrangement by hydride shifts, it has been shown by NMR spectroscopic analysis that the analogously constitute 1,3‐methyl‐1,2‐epoxybutane does not undergo a hydride shift when polymerized with boron trifluoride. Other epoxides of the type are shown also not to rearrange on cationic polymerization. The different behavior between the two systems is ascribed to differences in the types of carbonium ion intermediates involved in polymerization.
Organic sulfur compounds. XIX. Addition of dithiols to diallyl maleate: A new concept of polyester synthesis1
Authors: Oswald Alexis A. , Naegele Walter
Published: April 2003

Selective free radical polyadditions of dithiols to the allylic double bonds of diallyl maleate result in polyesters having maleic unsaturation. Using aliphatic 1,2‐ and 1,3‐dithiols a stepwise preparation of such polyesters is possible since the first thiol group reacts more readily than the second. NMR spectroscopy was found to be a most useful tool in determining the course and extent of such selective reactions. The polyesters can be readily crosslinked by an ionic MICHAEL‐type addition of dithiols to their maleic double bonds. Free radical copolymerization with styrene can also be used to produce crosslinked networks.
Siloxanmodifizierte polypyromellitimide
Authors: Kuckertz Von H.
Published: April 2003

Durch Polykondensation von 1,3‐Bis(aminopropyl)‐1,1,3,3‐tetramethyldisiloxan mit Pyromellitsäuredianhydrid bzw. Pyromellitsäurediäthylester wurden in organischen Lösungsmitteln lösliche und bei 180°C durch Spritzguß verarbeitbare Polymere erhalten. Bei Verwendung von 1,3‐Bis(m‐aminophenyl)‐1,1,3,3‐tetramethyldisiloxane als Aminkomponente entstanden spröde, wenig Iösliche, niedermolekulare Producte.
Polymerization of propylene oxide by diethylzinc/ketone catalysts
Authors: Sakata R. , Takeuchi K. , Yoshii H. , Haga K. , Onishi A.
Published: April 2003

Propylene oxide was polymerized by diethylzine/ketone system. Cacatalytic effects of twenty‐four ketones were examined. Methyl ketones and cyclic ketones were effective as a cocatalyst for the polymerization, while alkyl ketones with longer chain and β‐diketon were not. The reaction of the catalyst formation was discussed. Crystallinity of the polymers obtained was compared with that of polymers by diethylzinc/water or diethylzine/alcohol catalyst.
Über die autoxydation CH‐aktiver polymerisationsinitiatoren. XIV. Mitt. Polymerisationen und polymerisationsinitiatoren1
Authors: Bredereck Von Hellmut , Föhlisch Baldur , Franz Raimund , Tagoe Daved , Diebel Klaus , Krämer Botho
Published: April 2003

CH‐aktive Polymerisationsinitiatoren der allgemeinen Formel A‐CH(R)‐B (A und B: elektronenanziehende Gruppen, R: H oder Alkylgruppe) unterliegen in Gegenwart von Cu++ und Cl– der Autoxydation. Man beobachtet eine Parallele zwischen ihrer Autoxydationsgeschwindigkeit und Initiatorwirkung bei der Polymerisation von Methacrylsäuremethylester. Die Polymerisationsauslösung durch CH‐aktive Verbindungen wird daher auf ihre primäre Autoxydation zurückgeführt.
Kinetics of free‐radical polymerisation at high viscosities
Authors: Bogunjoko Julius S. T. , Brooks Brian W.
Published: April 2003

Methyl methacrylate und styrene were polymerised by a free‐radical process in solutions which contained dissolved polymer. The molecular weights of the dissolved polymer and the concentration of the radical generator 2,2'‐azoisobutyronitrile were varied. Rate data were compatible with a reaction scheme in which the mobility of some growing radicals was influenced by the solution viscosity. Correlations between radical mobility and viscosity were more consistent with the experimental results than correlations between radical mobility and volume fraction of dissolved polymer. The possibility of primary radical termination is examined and a means of clarifying the chain termination process is suggested.
Functional monomers and polymers, 109. Asymmetric inclusion polymerization of (E)‐ and (Z)‐2‐methyl‐1,3‐pentadiene in apocholic acid canals
Authors: Mijata Mikiji , Kitahara Yasuhiro , Takemoto Kiichi
Published: April 2003

Asymmetric inclusion polymerization of the prochiral monomers (E)‐ and (Z)‐2‐methyl‐1,3‐pentadiene (3a and 3b), in apocholic acid (2) canals was performed under various conditions to find out the factors controlling the asymmetric induction during the polymerization. Ozonolysis of the resulting polymers and subsequent transformation of the resulting 2‐methyl‐4‐oxovaleric acid (4) into its 2,4‐dinitrophenylhydrazone revealed the predominant formation of the (R)‐absolute configuration. The optical yield was high in the initial stage of the polymerization and decreased gradually as the polymerization proceeds. To obtain a high optical yield the polymerization was performed at low temperature applying a 1:1 mole ratio monomer/apocholic acid, and an irradiation dose < 1 Mrad. The optical yield amounted to 36% at maximum, which is the highest value obtained so far in the asymmetric polymerization of 1,3‐pentadiene derivatives using canal complexes or other known methods.
Synthèses de polysiloxanes organofonctionnels, 4. Les poly[(hydroxyméthyl)méthylsiloxane]s homogénes et hétérogènes
Authors: Reyx Danièle , Guillaume Pierre
Published: April 2003

Transformations of oxy(halomethyl)methylsilanediyle units or oxy(acetoxymethyl)methyl‐silanediyle units into oxy(hydroxymethyl)methylsilanediyle units in homogeneous and heterogeneous polysiloxanes were investigated. Si‐C‐cleavage and SiOSi‐rearrangement were studied on disiloxanes and oligosiloxanes used as models of the corresponding polymers. Methanolysis of poly[(acetoxymethyl)methylsiloxane]s and their copolymers catalysed by p‐toluenesulfonic acid was applied to obtain poly[(hydroxymethyl)methylsiloxane]s and their copolymers.
Nature of polymer matrix of immobilized enzyme composites obtained by radiation polymerization of bifunctional monomers and its effect on the enzymatic activity
Authors: Kumakura Minoru , Kaetsu Isao
Published: April 2003

Cellulase was immobilized on a porous polymer matrix which was formed by radiation polymerization of bifunctional monomers such as poly(ethylene glycol) diacrylates (1), and the nature of the porous polymer matrix and its effect on the enzymatic activity was studied. The porous structure of the polymer matrix was found to change markedly with the monomer concentration and irradiation temperature. The formation of the porous structure shows a discontinuous change in the temperature region of −10 to −40°C, due to the change in polymerization phase and mechanism. The enzymatic activity is strongly related to the pore size, the degree of hydration of the polymer matrix, and the particle size of the composite. The degree of hydration of the polymer matrix varies with the number of oxyethylene units in the monomers 1.
Polymerization of methyl methacrylate initiated by a Rh(I) complex and benzoyl peroxide
Authors: Kameda Noriyuki , Ishii Emiko
Published: April 2003

The polymerization of some vinyl monomers initiated by carbonylchlorobis(triphenylphos‐phine)rhodium(I) (RhCl(CO)(P(C6H5)3)2) and benzoyl peroxide (BPO) was studied. The polymerization ability was found to decrease in the following order: methyl methacrylate (MMA) > styrene > vinyl acetate > isobutyl vinyl ether. In the polymerization of MMA, the average molecular weight increases with an increase in monomer conversion. On the basis of the kinetic studies of the polymerization of MMA initiated by RhCl(CO)(P(C6H5)3)2 and BPO (the mole ratic [BPO]/[RhCl(CO)(P(C6H5)3)2]) was between 1 and 7, the rate of polymerization, Rp' can be expressed by the following equation:

The overall activation energy for the MMA polymerization was found to be 75,3 kJ/mol within the temperature range of 50 to 80°C. The composition curve of the copolymerization of styrene with MMA using RhCl(CO)(P(C6H5)3)2 and BPO agrees with that of the ordinary radical polymerization. On the basis of these results the initiation mechanism is discussed.
Acceleration effect of acids on the co‐dimer formation from 1‐(4‐chlorophenyl)ethyl esters and styrene
Authors: Kasai Hideaki , Kawabata Hiroshi , Yamaguchi Kazuo , Nakahama Seiichi , Yamazaki Noboru
Published: April 2003

A linear unsaturated co‐dimer of styrene and p‐chlorostyrene, 1‐phenyl‐3‐(4‐chlorophenyl)‐1‐butene (2), was preferentially produced by reaction of 1‐(4‐chlorophenyl)ethyl diphenyl phosphate (1) with styrene. The reaction was found to be extraordinarily accelerated by addition of trifluoromethanesulfonic acid. 1‐(4‐chlorophenyl)ethyl acetate reacts readily with styrene in the presence of trifluoromethanesulfonic acid to afford 2 in good yields, whereas the acetate is inert toward styrene in the absence of a super acid.