bluuebunny/crossref_metadata_2025 huggingface dataset:
Über die quellung resp. Inclusion der cellulose mit niederen fettsäuren
Authors: Staudinger von Hermann , Eicher Theo
Published: April 2003

Es wird der Unterschied zwischen Quellung und Inclusion bei der Einwirkung von niederen Fettsäuren auf Linters gezeigt. Die Ameisensäure vermag die Wasserstoffbrücken zwischen den Cellulose ketten zu sprengen, also die Cellulose zu quellen und in einen reaktionsfähigen Zustand überzufübren. Die Propionsäure und Buttersäure dagegen sind dazu nicht befähigt, können aber zwischen die Celluloseketten nach Vorquellung mit Wasser includiert werden. Diese „Inclusionscellulosen”︁ zeigen die gleiche Reaktionsfähigkeit wie die mit Ameisensäure gequollenen Cellulosen. Die Essigsäure nimmt eine Mittelstellung ein, sie quillt in der Kälte nur langsam, bei erhöhter Temperatur rasch; ferner kann sie durch Vorbehandlung der Cellulose mit Wasser includiert werden. Die Reaktionsfähigkeit der trockenen und includierten Cellulosen wird durch die Acetylierungsgeschwindigkeit mit Essigsäureanhydrid in Benzol (Überchlorsäure als Katalysator) charakterisiert.
Multimerisation: Assoziation und aggregation. III. Einfluß der offenen assoziation auf die ungestörten dimensionen von polyäthylenglykolen
Authors: Elias Von Hans‐Georg
Published: April 2003

Die STAUDINGER‐Indices [η] von Polyäthylenglykolen mit Molekulargewichten zwischen 62 und 38000 wurden bei 25°C in Wasser, Methanol, Dimethylformamied, Acetonitril, Dioxan, Tetrachlorkohlenstoff, Methylacetat und Benzylalkohol, und in Benzol bei 10 bzw. 37°C gemessen. Die Funktion [η]/M = f(M) durchläuft mit steigendem Viskositätsmittel des Molekulargewichtes Mv ein Minimum und steigt dann zuerst steil und später langsamer an. Die Extrapolation der Asymptoten bei hohen Molekulargewichten zu M → 0 ergibt unabhängig vom Assoziationszustand der Polyäthylenglykole in der verschiedenen Lösungsmitteln ein lim

equation image

Die konventionelle Auswertung über den Molekulargewichtsbereich vom Minimum aufwärts führt zu KΘ‐Werten, die mit steigender Gleichgewichtskonstante der Assoziation abnehmen. Bei kleinen Molekulargewichten nähern sich die STADUINGER‐Indices einem Grenzwert [η]0. Für nicht assoziierende Lösungsmittel wurde [η]0 = 2,5 ml/g gefunden. Mit steigender Assoziationskonstante fällt [η]0 zu tieferen Werten ab. Die Befunde werden durch intermolekulare Wasserstoffbrücken von der Hydroxyl‐Endgruppen zu den mittelständigen Äthergruppierungen gedeutet.
NMR observations of drawn polymers VI. Poly (ethylene oxide)
Authors: Olf H. G. , Peterlin A.
Published: April 2003

Wide line NMR spectra of cold drawn poly(ethylene oxide) (PEO) were recorded at temperatures between −196°C. and 66°C. as a function of the alignment angle between the draw direction and the magnetic field. Line width, second moment, and mobile fraction were determined and are discussed in terms of segmental motion. In agreement with other authors two motional processes were found. (1) The β‐process, commencing at temperatures around −45°C., probably occurs in non‐crystalline regions and causes the emergence of a narrow NMR line in addition to the broad one. (2) The β‐process was observed between 0°C. and the melting point (66°C.) and led to a pronounced decrease of the width of the broad line and of the second moment. This decrease was anisotropic and was greatest at the alignment angle γ = 45°. As a consequence of this the dependence of the line width and of the second moment on γ is changed: whereas both these quantities show at low temperatures (<0°C.) a maximum at γ = 45° and an absolute minimum at γ = 0°, near the melting point, a minimum close to γ = 45° and an absolute maximum at γ = 0° were found. These changes are explained by oscillations of the helical molecules around their axes in crystalline regions.
The influence of temperature on the plastic deformation of polyethylene
Authors: Corneliussen R. , Peterlin A.
Published: April 2003

Temperature influences the attainable draw ratio, the transparency of the drawn material, the long period and the intensity distribution in the small angle X‐ray diffraction pattern. Drawing at or below 80°C yields a first order small angle maximum with relatively large lateral width indicating a variation of lamellar surface orientation between 90° and 45° to the draw direction. Drawing above 80°C reduces the lateral width of the first order maximum and leads to the appearance of the second order. The thermal history of the starting material, quenched, slowly cooled, or annealed, affects the draw behavior. The long period, however, seems to be independent of the physical conditions of the initial sample. At 60°C, for instance, the drawing of polyethylene samples with a long period of 195, 250, 290, 310, and 380 Å yields a material with long periods between 170 and 180 Å.

Annealing drawn samples produces observable changes even at 90°C. At temperatures below 120°C annealing for 100 min yields long periods slightly below those for samples drawn at the same temperature. At 120°C and above the drawing and annealing show nearly the same long period. Annealing also greatly increases the intensity of the X‐ray small angle reflections, but at temperatures below 120°C causes only minor changes in the lateral width of the same reflections.
Polymerization of itaconic acid under high pressure
Authors: Nakamoto Hideo , Ogo Yoshiaki , Imoto Tatsuya
Published: April 2003

Radical polymerizations of itaconic acid were investigated under high pressure up to 5000 kg/cm2 in several different solvents.

The critical pressures under which polymerization does not take place were determined in each solvent and the relation between the dielectric constant of the solvent and the critical pressure was found to be linear. The overall rate of polymerization increases markedly with pressure and the activation volume indicates fairly large absolute values compared with those of other vinyl compounds.

The polymers obtained under high pressure are white and brittle having a somewhat hygroscopic property, are soluble in methanol, dimethylformamide and especially in water, and are insoluble in other organic solvents.
Linear conditions in chain systems with neighbour interaction. II. Application of structural conditions: Atactic polypropylene
Authors: Allegra Giuseppe
Published: April 2003

It is shown here how the theory proposed in the preceding paper may be applied to the conformational analysis of atactic polymers as well as of oligomers in solution. The calculation of the free mean‐square lengths of polypropylenes with various types and degrees of tacticity is discussed in detail. In particular, the chain distributions of d and I units, coresponding to the models taken into consideration, are closely represented by the MARKOFFian law. The agreement between our results and those obtained by FLORY et al. through Monte‐Carlo calculations is substantially good. The reasons why the configurational defects in nearly isotactic poly‐α‐olefins should be more closely represented by the (… dddlddd …) sequences than by the (… dddlll …) ones proposed by FLORY, avidenced.
Gitterstörungen in polyäthylen
Authors: Hosemann Von R. , Wilke W.
Published: April 2003

Es wird gezeigt, wie aus Messungen der Winkelabhängigkeit der Linienbreite in Röntgenweitwinkeldiagrammen von Hochpolymeren die kristallitgröße und die Gitterstörungen bestimmt werden können. In lösungskristallisierten linearen Polyäthylenen treten rein parakristalline Gitterstörungen auf, die thermodynamisch stabil sind. Verzweigtes Polyäthylen zeigt mit dem Verzweigungsgrad anwachsende Gitterstörungen und abnehmende Kristallitgrößen. Im schmelzkristallitgrößen linearen Polyäthylen werden Spannungen beobachtet; die Werte der Kristallitgrößen sind teilweise erheblich höher als im lösungskristallisierten Material. In Kettenrichtung sind die Gitterstörungen wesentlich kleiner als senkrecht dazu. Kombination von Rötgenmessungen mit anderen Untersuchungsmethoden (ESR, NMR, Suszeptibilität, Reißfestigkeit) geben die Möglichkeit, genauere Einblicke in den Verstreck‐ und Reißvorgang zu gewinnen.
Thermal properties of ethylene‐propylene block copolymers
Authors: Clegg G. A. , Gee D. R. , Melia T. P.
Published: April 2003

A precision, adiabatic, vacuum calorimeter and a differential scanning calorimeter have been used to measure the heat capacities of two ethylene‐propylene block copolymers containing 12 and 17 mole per cent ethylene, respectively, over the temperature range 80 to 500°K. An estimate has been made of heat capacity values below 80°K. Values of the heat capacity, entropy, enthalpy, and free energy are listed at lO°C intervals. Two first order transitions at 399 ± 3°K and 435 ± l°K were observed in both copolymers. These are attributed to the melting of ethylene and isotactic propylene blocks. Values for the heats of fusion of the copolymers are listed.
The dependence of excimer formation of polystyrene solutions on solvent and concentration
Authors: Nishihara Toshio , Kaneko Motozo
Published: April 2003

The fluorescence spectra of polystyrene solutions have been measured in various solvents. The ratio of the intensity ID of the excimer (short living excited dimer) band to the intensity IM of the monomer band depends on the solvent. The values extrapolated to diluted solutions may be related to the average density of segments in a polymer molecule. Above concentrations of 0.1 g/100 ml, the ratio ID/IM increases with increasing concentration, and the peak position of the excimer band shifts to a longer wavelength.
On the persulphate‐bisulphite‐Cu2+ initiated emulsion polymerization of vinyl chloride. Kinetics and mechanism in the presence of a complexing agent
Authors: Mørk P. C. , Ugelstad J.
Published: April 2003

The persulphate‐bisulphite‐Cu2⊕ initiated emulsion polymerization of vinyl chloride has been investigated in the presence of a metal‐ion complexing agent (trisodiumcitrate). In the range of concentrations investigated, the rate of radical production from the redox system was found to be 2nd order with respect to the concentration of NaHSO3 and independent of the persulphate concentration. The effect of the concentrations of citrate and copper ions was found to be strongly dependent on the ratio [citrate]t/[Cu]t (index t indicating total added amounts). In borax and phosphate buffer, the rate of polymerization was found to be proportional to [Cu]t1/4·[citrate]−1/2 at ratios larger than about ten. When the ratio approaches unity, an abrupt increase in rate was observed. A kinetic scheme based on the equilibrium reaction

is discussed. The effects of [Cu]t and [citrate]t, as predicted by this scheme, were calculated by computing numerical values of [Cu2⊕] according to the above equilibrium. This proved the theory to be in good agreement with the experimental results.
The use of matrices for a complete description of copolymers
Authors: Tosi Camillo , Allegra Giuseppe
Published: April 2003

Mathematical formalisms based on the application of matrix techniques were lately applied to multicomponent copolymerizations; they led to expressions giving the fractional distribution of each monomer present in a linear copolymer of a certain degree of polymerization.

In this paper an extension of these treatments, which allows us to describe in a conceptually simple way of the whole sequence distribution of copolymers.
The crystal structure of isotactic polyepichlorohydrin
Authors: Perego G. , Cesari M.
Published: April 2003

The crystal structure of poly(chloromethyl ethylene oxide) or polyepichlorohydrin has been carried out, by X‐ray diffraction technique. The parameters of the orthorhombic unit‐cell are:a= 12.16 Å,b= 4.90 Å,c= 7.03 Å, fairly coincident with those given by RICHARDS (Diss. Abstr.22(1961) 1029). Two space‐groups are proposed: Pna21and Pnam, the former being more probable. Chain conformation is exactly like that previously given by the authors for the poly‐propylene‐oxide. The side chloromethyl‐group lies on a plane perpendicular to the chain axis, in accordance with the staggered bonds principle.
Effect of unsaturated hydrocarbons on the polymerization of butadiene with nickel catalyst
Authors: Sakata Ryozo , Hosono Junichi , Onishi Akira , Ueda Kenichi
Published: April 2003

Effect of various aliphatic hydrocarbons on the cis‐1.4 polymerization of butadiene with nickel naphthenate/boron trifluoride etherate/triethylaluminum catalyst was investigated. It was observed that vinylcyclohexene, allenes, and acetylenes retarded the initiation and the propagation and enhanced the chain transfer. The retarding effect is stronger in the order: paraffin, monoolefin < vinylcyclohexene ≦ acetylene < allene = butadiene‐1.2 < methylacetylene < vinylacetylene. The microstructure of the polymer is not affected by the presence of these compounds. The retarding effect was discussed in terms of the coordination of the unsaturated hydrocarbons to the catalyst.
Plastic deformation of polypropylene. V. Annealing of drawn polypropylene
Authors: Baltá‐Calleja F. J. , Peterlin A.
Published: April 2003

Isotactic polypropylene samples drawn at 20 and 100°C to a draw ratio 6 and 10 were annealed with free and fixed ends between 40 and 155°C for periods of time between 1 and 103 min. All the annealing effects proceeded farther with unclamped samples free to shrink than with clamped samples. The disorientation of crystal lattice and the shrinkage are extremely fast reaching saturation values characteristic for the temperature of annealing. At higher annealing temperature, one could observe merely the saturation values with the whole transition being completed in less than 1 min. The long period growth, the increase in density, and the intensity of small‐angle X‐ray scattering are linear functions of the logarithm of annealing time and hence persist with gradually decreasing rate long after the completion of disorientation and shrinkage. The observed effects can be well explained on the basis of the two‐stage model of plastic deformation of crystalline polymers which assumes the formation of strong well‐aligned microfibrils connected by interfibrillar tie molecules.
The kinetics of the thermal decomposition of the peroxodisulphate ion in aqueous solutions of various cationic surface‐active agents
Authors: Crematy Edward P.
Published: April 2003

A study has been undertaken of the kinetics of the thermal decomposition of potassium peroxodisulphate in aqueous solutions of n‐butyltrimethyl‐, n‐butyltriethyl‐, and n‐octyltriethylammonium chlorides. It has been found that the rate of disappearance of the peroxodisulphate ion is markedly increased in the presence of the cationic surfactants. Experiments with allyl acetate (a free‐radical scavenger) show that there is no direct reaction between peroxodisulfate and surfactant, and that the increased rate of disappearance of the peroxide is due to a free‐radical induced decomposition.

The rate law has been elucidated, rate coefficients and activation parameters computed, and free‐radical mechanistic sequence discussed.
Topochemical reactions of monomers with conjugated triple‐bonds. IV. Polymerization of bis‐(p‐toluene sulfonate) of 2.4‐hexadiin‐1.6‐diol
Authors: Wegner Gerhard
Published: April 2003

Solid‐state polymerization of the bis‐(p‐toluene sulfonate) of 2.4‐hexadiin‐1.6‐diol was achieved by UV‐irradiation or by annealing the monomer crystals below their melting‐point. Deep red polymer crystals having the original shape of the monomer crystals exhibiting strong dichroism are obtained. Polymerization proceeds by 1.4‐addition to the conjugated triple‐bonds to form a polymer with three cumulated double bonds per baseunit and a fully conjugated backbone. Photopolymerization is rather fast and does not show an induction period. The relationship between ηsp/c‐values and conversion as well as X‐ray work indicates that the formation of nuclei must be an important feature of the reaction mechanism. Thermal (spontaneous) polymerization shows a considerable induction period and very high viscosity‐values are obtained for thermal polymers.
Kinetik der Polymerisationsauslösung mit aromatischen pinakolen
Authors: Braun Dietrich , Becker Knut H.
Published: April 2003

Vinylmonomere lassen sich durch aromatische Pinakole oberhalb von 40°C radikalisch polymerisieren. Die Polymerisationsauslösung erfolgt durch eine Wasserstoffübertragung der primär durch thermischen Zerfall der Pinakole gebildeten Diarylhydroxymethyl‐Radikale auf die Monomermoleküle. Hieraus ergibt sich theoretisch eine Proportionalität zwischen Polymerisationsgeschwindigkeit vBr und Initiatorkonzentration [I]1/2 sowie Monomerkonzentration [M]3/2; dieses Geschwindigkeitsgesetz kann experimentell bestätigt werden. Es wird aus kinetischen Untersuchungen geschlossen, daß die Wasserstoffübertragung in einem Übergangszustand erfolgt, der aus einem Monomermolekül und einem Initiatorradikal gebildet wurde.
Solvent effects in radical copolymerization III. Methacrylamide
Authors: Saini Guido , Leoni Alvaro , Franco Simone
Published: April 2003

The free radical copolymerization of methacrylamide with styrene and methyl methacrylate has been investigated at 70°C in solvents having different dielectric constants. A strong influence of the solvent on the copolymerization parameters has been observed. Such behaviour is quite similar to that found by the same authors for acrylamide copolymerization and differs completely from that found for N.N‐dialkyl acrylamide. The influence of the solvent properties (polarity, dielectric constant etc.) on the amide‐enol equilibrium is discussed.
The configuration of cellulose dissolved in iron‐sodiumtartrate
Authors: Valtasaari Lea
Published: April 2003

Viscosity and light scattering data on 10 cellulose samples in the iron‐sodiumtartrate solvent (FeTNa) are presented and examined in the light of the FLORY‐FOX treatment of dilute solution properties. The FLORY factor, Φ, is found to increase with mol. wt. approaching a constant value when M̄w exceeds 500 000. Good linear correlation with the data is found for [η] M̄w as a function of R. Functions proposed for evaluation of the unperturbed dimensions by means of intrinsic viscosity and mol. wt. have been tested on the present data. Good linear fit is obtained for six of these from medium to high molecular weight range. From the slope of the linear part of the STOCKMAYER‐FIXMAN plot, the second virial coefficient is calculated, according to KRIGBAUM, which is in good agreement with the experimental values obtained by light scattering. It is suggested that a decrease of flexibility with decreasing mol. wt. could result from immobilization of monomer‐monomer bonds in the cellulose‐iron complex formed on dissolution.
Vinyl polymerization initiated by the dimethylaniline N‐oxide/tosyl chloride system
Authors: Sato Tsuneyuki , Yoshioka Minoru , Otsu Takayuki
Published: April 2003

A study of the vinyl polymerization initiated by the system dimethylaniline N‐oxide (DMAO) in conjunction with tosyl chloride (TsCl) has been performed. According to the kinetic results of the polymerization of methyl methacrylate (MMA) and of the copolymerization of MMA with styrene, the polymerization proceeds via a radical mechanism. The rate of polymerization is given by the following equation:

equation image

and the overall activation energy was calculated to be 14.3 kcal · mole−1. According to the UV spectrum, the poly‐MMA obtained probably contains N‐methylanilinomethyl end groups.

A graft polymer was obtained by polymerization of MMA with DMAO and partially chlorosulfonated polyethylene (Hypalon‐30). From the results an initiation mechanism is proposed and discussed.
Equilibrium ring‐opening polymerization of mono‐ and multicyclic unsaturated monomers
Authors: Ofstead Eilert A. , Calderon Nissim
Published: April 2003

Equilibrium ring‐opening polymerization theory has been extended to cycloolefin polymerizations. Previous work had established the reversible nature of the olefin metathesis reaction, the basic process whereby cycloolefins undergo ring‐opening. The present work confirms the reversible character of cycloolefin polymerization for the cases of cyclopentene and bicyclo[4.3.0]nona‐3.7‐diene polymerization. Equilibrium conversion data for cyclopentene polymerizations have provided estimates of the enthalpy (−4.4 kcal/mole) and entropy (−14.9 cal/mole·deg) of polymerization. In addition, some factors governing the polymerizability of mono‐ and multicyclic monomers are discussed.
Topochemical polymerization of monomers with conjugated triple bonds
Authors: Wegner G.
Published: April 2003

Solid‐state polymerization of monomers with conjugated triple bonds turns out to be a versatile method for synthesis of crystalline polymers of high molecular weight exhibiting a fully conjugated backbone. The reaction is best described as an 1.4‐addition polymerization of the conjugated triple bonds giving rise to a polymer with three cumulated double bonds per repeating unit. The all‐trans configuration of the substituents is a consequence of the solid‐state reaction mechanism and is already predetermined by the packing of the molecules in the monomer lattice. It was shown by X‐ray analysis in the case of poly(2.4‐hexadiin‐1.6‐diol‐bis‐phenylurethane) that the polymer diacetylenes can be described by either a butatriene structure or by a mesomeric en‐in‐structure.
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Polymerization of the colorless monomer crystals is achieved by irradiation with UV‐ or high‐energy radiation or by simply annealing the monomer crystals below their melting point. Deep red, blue or black polymer crystals are obtained exhibiting strong dichroism with the fibre axis as the direction of main absorption. These crystals possess semiconducting properties (EA = 0.6–1.0 eV, depending on the substituents at the conjugated backbone).
Phase equilibrium of the cellulose derivatives determined by differential thermal analysis. 1. Methylcellulose/water
Authors: Kagemoto Akihiro , Baba Yoshihiro , Fujishiro Ryoichi
Published: April 2003

A DTA apparatus suïtable for measuring polymer solutions has been constructed. By using this apparatus the phase equilibrium of the system methylcellulose/water was studied. The precipitation temperature was determined from the DTA curve which shows a sigmoidal shape. The thermodynamic parameters for entropy Ψ1 = 2.11 and enthalpy, χ1 = 2.13 (at 328.8°K) and the theta temperature, Θ = 59.5°C were estimated.
New completely aliphatic anionic membranes from polymers of unsaturated tertiary amines. Part I. Preparation and properties
Authors: Credali Lino , Chiolle Antonio , Parrini Paolo
Published: April 2003

New anionic membranes of completely aliphatic structure have been prepared starting from homopolymers and copolymers of unsaturated aliphatic tertiary amines.

These membranes have an exchange capacity ranging from 0.5 to 4.0 meq/g dry substance and a permoselectivity exceeding 90%.

Using reversible Ag/AgCl electrodes, the membrane potential for these membranes has been measured in various NaCl solutions, in order to determine the transport number. Moreover, the membrane conductivity has been determined as function of the concentration of the electrolyte in the external solution.

These membranes, since they do not contain the arylalkyl‐trimethylammonium group, offer greater resistance to alkaline conditions than conventional ones.
Plastic deformation of nylon 6 single crystals and thin membranes
Authors: Sakaoku K. , Peterlin A.
Published: April 2003

The deformation of single crystals shows two preferential directions for crack formation at 60° to each other. The cracks open very little on crystals lying directly on the Mylar substrate and substantially more on the higher layers of a multilayer crystal. The primary crack direction is parallel to the plane of hydrogen bridges. The microfibrils bridging the cracks are too short for a good dark field electron micrograph. Deformed thin membranes occasionally show a lamellar structure. After annealing at 215°C well oriented single crystal blocks belonging to microfibrils can be observed.
Polymere aus Nitrilen. I. Anionische Polymerisation von Bernsteinsäuredinitril
Authors: Wöhrle D.
Published: April 2003

Bernsteinsäuredinitril wurde in Gegenwart von anionisch angreifenden Katalysatoren zu Polymeren umgesetzt. Die Polymerisation des Nitrils z. B. mit Natriummethylat in Methanol führt zum Poly(1‐pyrrolin‐2‐yl‐5‐ylidennitrilo), welches Halbleitereigenschaften mit σ300°K ∼ 10−8Ω−1cm−1 aufweist. Bei der Umsetzung von Bernsteinsäuredinitril mit Kalium‐tert‐butylat in Substanz erhält man dagegen Poly[(4‐amino‐2.5.6‐pyrimidintriyl)‐2.6‐dimethylen], welches Isolatoreigenschaften hat. Die Ergebnisse der thermischen Analysen werden mitgeteilt.
A novel method of determination of reactivity ratios in binary and ternary copolymerizations
Authors: Jaacks Volker
Published: April 2003

The determination of reactivity ratios is simplified by using an excess of one monomer (M1) at a time large enough that the copolymers will have a very small content of the other monomer (M2). In this case chain propagation takes place almost exclusively by addition to polymer radicals with a terminal M1‐unit (P) and monomer consumption by propagation of P may be neglected. One reactivity ratio (r1) is obtained from monomer conversions by means of a simple integrated equation which is valid up to high conversions. A calculation is proposed in order to account for the neglected propagation via P. The other reactivity ratio (r2) is obtained from copolymerizations with excess M2.

As the new method uses an integrated form of the MAYO equation it permits the determination of monomer conversions directly by gas chromatography of unreacted monomers. Thus, if desired, analysis of copolymers can be avoided. The gas chromatographic method has been tested with the radical copolymerization of styrene and methyl methacrylate.

In ternary and quaternary copolymerizations the new method offers particular advantages.
Radikalbildung und Kettenbruch bei der Radiolyse von Polypropylensulfid
Authors: Raven A. V. , Hesse P. , Heusinger H.
Published: April 2003

Die Radiolyse von Polypropylensulfid mit Mercapto‐ und Thioätherendgruppen wurde untersucht. Die Ergebnisse der Molekulargewichtsveränderung mit der Dosis ergeben, daß statistischer Kettenbruch auftritt (GBruch = 0,4–0,7). Folgende Radikale konnten ESR‐spektroskopisch identifiziert werden:
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Es wird ein Mechanismus aufgezeigt, der die Radikalbildung mit dem Kettenbruch in Zusammenhang bringt. Hieraus geht hervor, daßB bevorzugt Spaltung von CC und nicht von CS‐Bindungen stattfindet.
Untersuchungen über den einfluß der ladungsdichte auf die gegenseitige desaktivierung von polyion‐makroradikalen
Authors: Görlich Werner , Schnabel Wolfram
Published: April 2003

Mittelständige Makroradikale R• wurden in wäßriger Lösung bei Raumtemperatur durch H‐Abstraktion (•OH + RH → H2O + R•) aus folgenden Polymeren erzeugt: Polyvinylalkohol (PVA), partiell mit Glyoxylsäure acetalisierter PVA, Copolymere aus Vinylpyrrolidon/Acrylsäure und Vinylalkohol/Acrylsäure. Die biomolekulare Geschwindigkeitskonstante kR der Reaktion R• + R• wurde mit der Methode der Pulsradiolyse gemessen. Im Falle des PVA ist kR im Polymerisationsgradbereich 2·103 bis 2·104 unabhängig vom Polymerisationsgrad der Makroradikale. Im Falle von Polyelektrolyten mit Kettenlängen zwischen 4·103 und 2·104 ergab sich folgendes: Beträgt der Gehalt xi an ionisierten Grundbausteinen weniger als 0,5 Mol‐%, so steigt kR mit zunehmendem xi an (maximal um den Faktor 4). Diese Zunahme wird auf die Knäuelexpansion zurückgeführt, die eine Folge der intramolekularen COULOMBschen Abstoßung ist. Im Bereich xi > 0,5 Mol‐% kommt die intermolekulare Abstoßung voll zur Wirkung, und kR fällt um etwa drei Größenordnungen ab.
Essais d'interprétation du gonflement à l'équilibre de réticulats‐modèle préparés par voie anionique
Authors: Haeringer Arnaud , Hild Gerard , Rempp Paul , Benoit Henri
Published: April 2003

Une série homologue de gels de polystyrène a été préparée par voie anionique dans des conditions standard. Seule varie d'un échantillon à l'autre la masse moléculaire des éléments linéaires compris entre deux noeuds successifs. La fonctionnalité de ces derniers n'est pas accessible à l'expérience. Le taux de gonflement à l'équilibre de ces gels a été étudié et il a été établi que le modèle du gel gaussien idéal, décrit par DUSEK et PRINS peut leur ětre appliqué, moyennant quelques hypothèses concernant l'état de relaxation et le paramètre d'interaction avec le solvant. La fonctionnalité des noeuds est de l'ordre de 4, pour cette série de gels.
Photo‐sensitized polymerization of styrene under high pressure
Authors: Ogo Yoshiaki , Yokawa Masaru , Imoto Tatsuya
Published: April 2003

The polymerization of styrene, photosensitized by azocyclohexane‐1,1′‐dinitrile, was studied at 30°C over a pressure range of 1 to ca. 1000 bar. The average lifetimes of the growing polymer chains were determined by the rotating‐sector method. By measuring the effect of pressure on the individual reactions of styrene polymerization, the activation volumes for the propagation and the termination were obtained as −17,9 cm3/mol and 13,1 cm3/mol, respectively. The overall activation volume was also measured as −17,9 cm3/mol and was nearly equal to that calculated from the individual activation volumes (−17,8 cm3/mol). The propagation rate constant increases exponentially with pressure, whereas the termination rate constant decreases rapidly up to 500 bar and then decreases slowly as the pressure increases further.
Über mehrparameterkorrelationen der kationischen polymerisation von vinylmonomeren: Einfluß des katalysatorsystems
Authors: Heublein Günther , Dawczynski Horst
Published: April 2003

Für die kationische Polymerisationp‐substituierter Styrole wurden unter Standardbe‐+gungen die Einflüsse der Lewiskatalysatoren sowie der Cokatalysatoren auf die Bruttopolymerisationsgeschwindigkeit (kBrutto) und den Durchschnittspolymerisationsgrad (DP) der erhaltenen Polymeren untersucht. Als Parameter wurden Leitfähigkeitswerte (χKat.) sowie Glaselektrodenpotentiale (εGlas/Kat.) neu eingeführt. Ihre Korrelation mit logkBruttobzw. logDPliefert lineare Abhängigkeiten.
The grüneisen constant of polymers
Authors: Warfield R. W.
Published: April 2003

A method based on the pressure dependence of the bulk modulus was developed for determnining the Lattice Grüneisen Constant, γL, of polymers. This technique was applied to a series of polymers and the results indicated that γL for most polymers lies between 4 and 9. These results were discussed in terms of the anharmonic properties of polymers and, in particular, in terms of the interchain specific heat.
Infrared spectroscopic studies of polymer transitions, 4. A second‐order transition of cellulose triacetate in the vicinity of 30°C
Authors: Ogura Katsuyuki , Miyachi Yuko , Sobue Hiroshi , Nakamura Shigeo
Published: April 2003

A second‐order transition of cellulose triacetate at approximately 30°C was studied by polarized infrared spectroscopy. The temperature dependences of infrared dichroismus were examined for the 900cm−1 (C1H bending vibration) and 600 cm −1 (acetyl group frequency) bands. The former changed at about 30°C, whereas the latter did not show any remarkable change. These results suggest that the transition observed here is probably related to the conformational change of the pyranose ring. The transition mechanism is supposed to be associated with the chair (C 1)‐boat (B) transformation of the pyranose ring at the folding of the cellulose molecule.
Sequenzspezifische Cooligokondensation von Nucleinsäure‐Bausteinen mit Affinitäts‐Schutzgruppen, 2. Cooligomere von 5′‐O‐[p‐Anisyldiphenylmethyl]thymidin und Desoxynucleotiden
Authors: Seliger Hartmut , Schütz Helmut , Philipp Manfred
Published: April 2003

Die Cooligokondensation von 5′‐O‐[p‐Anisyldiphenylmethyl]thymidin mit Thymidylsäure und Derivaten der Desoxycytidylsäure und Desoxyguanylsäure wurde untersucht. Die Cooligomeren MMTrdT(pdN)n (N = Nucleosid) wurden von den Homooligomeren und nicht umgesetztem Nucleotid durch Chromatographie auf einer Tritylcellulose‐Säule abgesondert und anschließend auf einer Diäthylaminoäthylcellulose‐Säule nach Kettenlänge getrennt. Im bestuntersuchten Beispiel, der Cooligokondensation mit N‐Isobutyryl‐desoxyguanosin‐5′‐phosphat, wurde die Nucleosidkomponente vollständig in Cooligomere eingebaut: die Ketten der Länge 2, 3, 4 und 5 wurden in 77‐, 18‐, 3‐ und 2proz. Ausbeute erhalten. Die erzielbare mittlere Kettenlänge kann u. a. durch Variation der Schutzgruppen und des Komponentenverhältnisses beeinflußt werden.
Turbidimetric studies of aqueous poly(vinyl alcohol) solutions
Authors: Peppas Nikolaos Ath
Published: April 2003

A freezing‐thawing process of aqueous poly(vinyl alcohol), (PVA) solutions was undertaken to study the supermolecular PVA structures produced. Aqueous solutions of 2,5 to 15 wt.‐% PVA were frozen at −20°C for 45 to 120min and were subsequently thawed for long periods of time (up to 12h) at 23 ± 1°C. The transmittance of visible light was recorded as a function of thawing time. Determination of the parameters of the supermolecular particles in the PVA solutions was done by application of Klenin's theory. The average radii of the particles were in the order of 1,6–2,3 μm.
Infrared spectroscopic studies on polyethylene, 1. The measurement of low levels of chain branching
Authors: Baker Clive , Maddams William F.
Published: April 2003

The problems encountered in the infrared spectroscopic estimation of the low levels of chain branching present in high density polyethylene, using the compensation method, are discussed systematically. The precision to be expected has been determined and it is shown that, if possible, a correction should be applied for methyl groups present at the chain ends. This is feasible with some types of polymer but more difficult with others. The compensating wedge in the reference beam of the spectrometer should be made of polymethylene rather than a high molecular weight polyethylene. The ultimate sensitivity of the manual compensation method is about one methyl branch per two thousand carbon atoms. However, when this is supplemented by computer smoothing and off‐line computation of average transients (C.A.T.), a significant improvement is obtained in the signal to noise ratio, and branching levels down to 0,1 methyl groups per thousand carbon atoms are readily measured.
Infrared spectroscopic studies on polyethylene, 4. The examination of drawn specimens of varying stress crack resistance
Authors: McRae Margaret A. , Maddams William F.
Published: April 2003

Infrared spectra, with both unpolarised and polarised radiation, have been obtained for a series of Phillips type high density polyethylenes of varying stress crack resistance. They were examined after cold drawing, by neck propagation, under standard conditions, and the presence of uniaxial orientation was confirmed by X‐ray pole figure measurements. Intensity measurements with unpolarised radiation on the bands at 1080, 1352, and 1894 cm−1 showed that with samples of bad stress crack resistance both the folds and the tie chains increase in concentration at the expense of the regularly folded chains in crystalline regions, whereas only the tie chains increase with samples having good stress crack resistance. Dichroic measurements on nine bands, the majority of them characteristic for methylene groups in gauche and trans conformations in amorphous regions, show that there is no marked degree of orientation of the chain folds or tie chains with samples of good stress crack resistance. However, there is significant orientation, particularly of the tie chains, for samples with poor stress crack resistance.
Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 2. Aliphatische polyester
Authors: Lüderwald Ingo , Urrutia Hernando
Published: April 2003

Die Abbaureaktionen von Polyestern aus Adipinsäure und Äthylenglykol 1a, Tetradeuteroäthylenglykol 1b, 1,3‐Propandiol 1c und 2,2′‐Oxydiäthanol 1d sowie aus Bernsteinsäure und Äthylenglykol 2a, 1,4‐Butandiol 2b und 2,2‐Dimethyl‐1,3‐propandiol 2c wurden im Massenspektrometer untersucht. Die Polymeren wurden direkt in der Ionenquelle des Massenspektrometers pyrolysiert und die entstehenden thermischen Bruchstükke durch Elektronenstoß ionisiert und fragmentiert. Die Pyrolyse‐ und Fragmentierungsreaktionen lassen sich nebeneinander nachweisen.

Die Kenntnis der Mechanismen beider Abbauschritte ermöglicht es, strukturisomere Polyester zu unterscheiden.
Feldionen‐ und Elektronenstoß‐Massenspektrometrie von Polymeren und Copolymeren, 5. Aliphatische und aromatische Polyamide und Polyimide
Authors: Düssel Heinz‐Jürgen , Rosen Heinz , Hummel Dieter O.
Published: April 2003

Die aliphatischen Polyamide Polyamid‐6 (1), Polyamid‐6,6 (2) und die aromatischen Polyamide der Terephthalsäure mit verschiedenen Diaminen [p‐Phenylendiamin, (3), 4,4′‐Biphenylylendiamin, (4), 4,4′‐Oxydianilin, (5)] sowie Polyimide der Pyromellitsäure mit aliphatischen Diaminen [Äthylendiamin, (6), Hexamethylendiamin, (7)] und aromatischen Diaminen [4,4′‐Biphenylylendiamin, (8), 4,4′‐Methylendianilin, (9), 4,4′‐Isopropylidendianilin, (10), 4,4′‐Oxydianilin, (11)] wurden bei Temperaturen zwischen 800 K und 1073 K im Vakuum des Hochtemperatureinlaßsystems eines Massenspektrometers pyrolysiert und durch Feldionenmassenspektrometrie untersucht. Amine, Amide, Imide und Nitrile sind charakteristische Fragmente des thermischen Abbaus. Die Abbaumechanismen, welche durch Struktur und Ausbeute der thermischen Zersetzungsprodukte bestimmt sind, werden beschrieben.
A comparative electric birefringence study of hydroxyethyl cellulose and other cellulose derivatives in water
Authors: Foweraker Alan R. , Jennings Barry R.
Published: April 2003

Both the amplitude of the electric birefringence and the rotary relaxation time have been measured for each of six samples of hydroxyethyl cellulose in water in the molecular weight range 3.104 to 6.105. Both these electrical and hydrodynamical properties have been considered in terms of a number of conformation models including the rigid rod, the weakly bending rod, the worm‐like coil, and the freely jointed chain. At sufficiently low molecular weight, rigid rod behaviour is indicated. This changes to a very flexible rod at higher molecular weights. In addition, a ratio of the electrical parameters as for an equivalent rod to the equivalent rod length indicates an important characteristic factor for these molecules which is a sensitive indicator of molecular flexibility. This is illustrated by comparing the data with similar results for other members of the cellulose family namely, amylose, methyl cellulose, and sodium carboxymethyl cellulose.
Infrared spectroscopy of semicrystalline poly(vinyl alcohol) networks
Authors: Peppas Nikolaos A.
Published: April 2003

Infrared spectroscopy was used for the quantitative determination of the degree of crystallinity of semicrystalline crosslinked polymeric films with particular application to the characterization of poly(vinyl alcohol) (PVA) networks. The intensity of the 1141 cm−1 band of the IR spectrum of PVA is sensitive to crystalline parts of the polymeric chains. A correlation between the degree of crystallinity and the intensity of this band was established. The experimental results were in accord with crystallinities obtained by density measurements of the same samples, after swelling in water until thermodynamic equilibrium. The crystallinities depended, however, on the time‐temperature history of the samples. Using this method, it is verified that the swelling process of the network does not affect the crystalline parts of the PVA chains.
Preparation, fractionation, and structure of block copolymers polystyrene‐poly(carbobenzoxy‐L‐lysine) and polybutadiene‐poly(carbobenzoxy‐L‐lysine)
Authors: Billot Jean‐Pascal , Douy André , Gallot Bernard
Published: April 2003

AB block copolymers with a polyvinyl block (polystyrene or polybutadiene) and a polypeptide block (poly(carbobenzoxy‐L‐lysine)) were prepared by the following method: at first the polyvinyl block was synthesized by anionic polymerization, then its living end was transformed into a primary amine function and it was used as a macromolecular initiator for the polymerization of the N‐carboxy anhydride (NCA) of an α‐amino acid. After fractionation, studies of the copolymers by IR spectroscopy and X‐ray diffraction showed, that they exhibit a lamellar structure in dioxane solution and in the dry state. In this lamellar structure the polypeptide chains, present in an α‐helix conformation, are arranged in an hexagonal array and are folded.
Mechanism of the polymerization of acrylamide initiated by the glycerol/Ce(IV) redox system
Authors: Rout Swoyam P. , Rout Anuradha , Mallick N. , Singh Baishnab C. , Santappa M.
Published: April 2003

The mechanism of the polymerization of acrylamide in aqueous medium initiated by the glycerol (R)/Ce(IV) redox system was studied. The rate of monomer disappearance was found to be directly proportional to [M]3/2, and R1/2 at lower concentrations of Ce(IV). The rate of the disappearance of ceric ions was found to be inversely proportional to [M] and directly proportional to [Ce(IV)] and [R]. Consistent with the findings of earlier investigations, a complex formation between monomer, acrylamide, and ceric ion is indicated. The experimental results show the termination to be mutual. On the basis of these and other kinetic results, an appropriate mechanism is proposed. At higher concentration of Ce(IV), a different mechanism seems to operate. The rates of disappearance of both the monomer and ceric ions are retarded on addition of anions like HSO4−, SO4− −, or CIO4−, but they are accelerated on the addition of Mn(II) ions. Interpretations of the above observations are furnished.
Enthalpy of polymerisation of 7‐oxabicyclo[2.2.1]heptane, and exo‐ and endo‐2‐methyl‐7‐oxabicyclo[2.2.1]heptane
Authors: Andruzzi Fulvio , Pilcher Geoffrey , Virmani Yogesh , Plesch Peter H.
Published: April 2003

The enthalpies of combustion of poly(oxy‐1,4‐cyclohexylene) formed from 7‐oxabicyclo[2.2.1]heptane (1) and of its derivatives formed from exo‐ and endo‐3‐methyl‐7‐oxabicyclo[2.2.1]heptane (2a and 2b) have been measured. From literature values for the enthalpies of combustion of the liquid monomers, the enthalpies of polymerisation have been derived: −ΔH(1→c)=44,3±1,9, 49,7±2,6, and 45.4±3,1 kJ mol−1, respectively. The results indicate a minimum strain energy in these polymers of ca. 15 kJ mol−1. The estimated entropies of polymerisation yield ceiling temperatures of 320, 240, 200°C respectively for the three bicyclic ethers.—The reasons for the discrepancy between our present −ΔH(1→c) for the endo compound and that previously reported2, are explained.
The cyclo‐copolymerization of diallyl compounds and sulfur dioxide, 6. 1,6‐Heptadiene and sulfur dioxide
Authors: Amemiya Yasuhiro , Katayama Masamichi , Harada Susumu
Published: April 2003

Copolymers from 1,6‐heptadiene (1) and SO2 with various mole ratios of their units were prepared. Their structures were studied by elemental analyses, IR and 1H NMR spectroscopy. Structures containing a cyclopentane ring (2) and such containing a thiane ring (3) in the main chain are proposed.
Interferenzmikroskopische charakterisierung von faserstrukturen, 1. Die ermittlung ortsabhängiger strukturparameter von fasern
Authors: Kühnle Gerhard , Schollmeyer Eckhard , Herlinger Heinz
Published: April 2003

The interferometric determination of refractive indices of fibers as a function of the radius of the fiber allows statements about order and orientation along the fiber radius and therefore gives an important contribution to the analysis of the structure of fibers.

An analytical model for the interpretation of interferograms of fibers is developed; its application is demonstrated in comparison with a shell model for the example of a poly(ethylene terephthalate) fiber.
Enzyme‐analogue built polymers, 4. On the synthesis of polymers containing chiral cavities and their use for the resolution of racemates
Authors: Wulff G. , Vesper W. , Grobe‐Einsler R. , Sarhan A.
Published: April 2003

With the aid of a chiral template molecule functional groups could be placed in a highly crosslinked polymer in such a way that they are present in a chiral cavity in a given stereochemistry. By this method methyl, resp. 4‐nitrophenyl α‐D‐mannopyranoside‐2,3; 4,6‐di‐O‐(4‐vinylphenylboronate) (1a, resp. 1b) were copolymerized to macroporous polymers from which the templates methyl, resp. 4‐nitrophenyl α‐D‐mannopyranoside (2a, resp. 2b) could be split off in return. It could be shown that such polymers with two boronic acid groupings within the chiral cavity possess a good ability for the resolution of racemates of the template used. In the case of the separation of the enantiomers of 2b separation factors up to 2,27 could be obtained. The overall optical enrichment in a chromatographic separation amounted to 87%.
Polymerizations of 1‐(9‐anthryl)ethyl methacrylate and charge‐transfer complex formations with its polymers
Authors: Iwatsuki Shouji , Inukai Kenji
Published: April 2003

1‐(9‐Anthryl)ethyl methacrylate (9AEMA) was prepared by condensation of 1‐(9‐anthryl)ethanol with methacryloyl chloride. The rate of AIBN initiated polymerization of 9AEMA in benzene at 60°C was intermediate between the polymerization rates of styrene and methyl methacrylate. 9AEMA/styrene copolymerization studies at 60°C resulted in the copolymerization parameters r9AEMA = 0,42±0,07 and rst = 0,37 ± 0,08. Charge transfer complexes are formed between p‐ chloranil and the 9AEMA homo‐ and copolymers. The absorption maxima of the CT‐complexes shifted to higher wavelengths with increasing 9AEMA content of the copolymers, whereas the equilibrium constant of the CT‐complex formation was independent of copolymer composition. Both the complex formation enthalpies and entropies decreased with increasing 9AEMA content of the copolymers.
Influence of nucleating agents on the crystallization of 6‐polyamide
Authors: Gurato Giorgio , Gaidano Dino , Zannetti Roberto
Published: April 2003

The influence of two nucleating agents on the crystallization parameters of 6‐Polyamide was investigated by differential scanning calorimetry and some substantial differences for the crystallization rate of the examined polymers were determined. The induction times ti, the semicrystallization times t1/2, the crystallization rate constants k, and the Avrami n coefficients were measured and related to the different characteristics and morphology of the specimens. The experimental data are represented in form of various plots and the microscopic examination of thin sections of the polymers allows to extend the study, showing remarkable differences in specimens morphology in correspondence of the nucleation effect.
Polymerization of lactams, 22. Effect of the reaction conditions on the anionic polymerization of 2‐pyrrolidone (part 2)
Authors: Kušková Marie , Roda Jan , Králíček Jaroslav
Published: April 2003

The effects of temperature, initiator and activator concentrations, and their mole ratios on the yield of the anionic polymerization of 2‐pyrrolidone and on the molecular weight of the resulting polymer were investigated. Potassium tert‐butoxide was used as the polymerization initiator, and N‐benzoylpyrrolidone as the activator. Optimum polymerization conditions were determined with the help of statistical planning of the experiments with the orthogonal composite design method.
Electrical properties of polyacetylene with various cis‐trans compositions
Authors: Shirakawa Hideki , Ito Takeo , Ikeda Sakuji
Published: April 2003

The electrical conductivity of crystalline polyacetylene films having various cis‐trans compositions was measured. The resistivity and the energy gap of a 92,5% trans polymer were 1,01·104Ω·cm and 0,56 eV, respectively, whereas the values of a 20,0% trans polymer were 2,35·108Ω·cm and 0,93 eV, respectively. These differences are discussed in terms of the effective conjugation length estimated from visible spectra and ESR measurements, and the spacing between molecular planes obtained by x‐ray diffraction measurements.