bluuebunny/crossref_metadata_2025 huggingface dataset:
Sedimentation studies on amylose acetate in nitromethane solution
Authors: Banks W. , Greenwood C. T. , Hourston D. J.
Published: April 2003

Measurement of the sedimentation coefficient of 12 amylose acetate fractions

in nitromethane solution showed that the relation

holds. Unperturbed dimensions were obtained using the COWIE‐BYWATER treatment of the sedimentation data. The FLORY‐MANDELKERN Constant, β, was independent of molecular weight, indicating that there was negligible draining of the amylose acetate moleclue in the molecular weight examined. It is concluded that the amylose acetate is extended in solution as a result of solute‐solvent interaction rather than to a high degree of steric hindrance; the polymer behaves as a random coil in agreement with the FLORY theory.
Ceric ion‐reducing agent redox initiated vinyl polymerisation
Authors: Subramanian S. V. , Santappa M.
Published: April 2003

Ceric perchlorate/formaldehyde (F)redox couple initiated polymerisation of the monomer methyl acrylate (MA), acrylonitrile (AN), and methyl methacrylate (MMA) in perchloric acid (25°C) was carried out. The rate of polymerisation was directly proportional to [M]2 and [F] for all the systems. The rate was independent of [Ce4+] for the systems with MA or AN, but inversely proportional to [Ce4+] with MMA as the monomer. The rate of ceric disappearance was directly proportional to [Ce4+], [F], and [M]. The results were explained by a kinetic scheme involving the oxidation of the substrate by Ce4+ to give the primary radical and further reaction of the latter with Ce4+ to give the final product, and initiation of polymerisation both by Ce4+ and the primary radical, propagation followed by termination by the metal ion. Only with MMA as the monomer, the initiation by Ce4+ was found to be negligible compared to that by primary radicals. In the system with the reducing agents t‐butanol and n‐butanol, there was found to be 1:1 complex formation between the substrate and Ce4+. Otherwise the scheme is similar to that proposed for the Ce4+/HCHO/HClO4/AN (MA) systems.
Cationic polymerization of formaldehyde
Authors: Yamaguchi Tadashi , Kawasaki Toshio , Matsuda Hiroshi
Published: April 2003

Cationic polymerization of monomeric formaldehyde has been studied at low temperature. It was found that high molecular weight polyoxymethylene with the reduced viscosity higher than 1.0 dl/g was readily obtained when the polymerization of formaldehyde was carried out in saturated hydrocarbons in the presence of LEWIS acids, BRÖNSTED acids, I2, ICl ICl3, IBr, sulfur dioxide and binary systems of sulfur dioxide with these compounds at considerably low temperature. The degree of polymerization was effected by the polymerization conditions, especially solvent, polymerization temperature and addition of chain transfer agents such as water, formic acid, methanol or methyl formate.
Syntheses and reactions of functional polymers. XXXI. Syntheses and some properties of polyethylenimines containing 2‐oxazolidone groups
Authors: Endō Takeshi , Okawara Makoto
Published: April 2003

Some polyethylenimines containing 2‐oxazolidone ring in the side chain were synthesized by (1) the MANNICH type reaction of formaldehyde, 2‐oxazolidone, and polyethylenimine, (2) polymerization of N‐(1‐azirinomethyl)‐2‐oxazolidone, and (3) reaction of N‐hydroxy‐methyl‐2‐oxazolidone with polyethylenimine. These polymers were soluble in water, but insoluble in common organic solvents.They formed the complexes with phenol or p‐toluene sulfonic acid in alkaline solution.
Multimerisation: Assoziation und aggregation. VII. Poly‐γ‐benzyl‐L‐glutamat in reinen lösungsmitteln
Authors: Gerber Von Jakob , Elias Hans‐Georg
Published: April 2003

Molekulargewichte und Virialkoeffizienten von 5 Poly‐γ‐benzyl‐L‐glutamaten (PBLG) mit Gewichtsmitteln des Molekulargewichtes zwischen 9600 und 550 000 wurden durch Streulicht und Osmose‐Messungen in Dimethylformamid (70 und 25°C) sowie bei 25°C in Dichloressigsäure, Dioxan, 1.2‐Dichloräthan und Chloroform bestimmt. In DMF bei 70°C ist PBLG mit höheren Molekulargewichten assoziiert, nicht aber mit niedrigen. Bei 25°C ist PBLG jeden Molekulargewichtes in DMF assoziiert. Bei 120°C wird PBLG in DMF abgebaut. In Dichloressigsäure bei 25°C ist die Assoziation bei den niedrigen Molekulargewichten stark, verschwindet aber bei den höheren Molekulargewichten. In Dichloressigsäure erfolgt bei 25°C kein Abba. Die Assoziation nimmt bei Dioxan und Chloroform ebenfalls mit steigenderm Molekulargewicht ab. In diesem Lösungsmittel folgt die Assoziation dem Typ der geschlossenen Assoziation, und zwar ausschließlich über Endgruppen. In Dichloressigsäure ist sie dagegen vermutlich vom Typ der offenen Assoziation. Die Virialkoeffizienten in helicogenen Lösungsmitteln sind unabhängig vom Molekulargewicht des Unimeren, dem Assoziationsgrad und der chemischen Natur des Lösungsmittels, mit Ausnahme des Produktes mit dem Molekulargewicht 9600. Aus den Virialkoeffizienten berechnet sich eine Ganghöhe der Helix von 1,6 Å pro Grundbaustein, was für eine α‐Helix (1,5 Å) spricht. Die abweichenden Befunde der Literatur können durch die Assoziation gedeutet werden.
Stereoregularity and dipole moments of optically active poly‐alkyl‐vinyl‐ethers
Authors: Luisi P. L. , Chiellini E. , Franchini P. F. , Orienti M.
Published: April 2003

Dipole moments of some samples having different stereoregularity of poly‐[(S)‐l‐methyl‐propyl]‐vinyl ether (A) andn poly‐[(S)‐2‐methyl‐buthyl]‐vinyl ether (C) have been determined and compared with those of samples having comparable stereoregularity of polyisopropyl‐vinyl ether (B) and poly‐isobutyl‐vinyl ether (D).

The results indicate: (a) no remarkable dependence of dipole moments on stereoregularity, except for (B), of which the most isotactic fraction has the lowest moment; (b) the dipole moment of the most stereoregular fraction of (A) is higher than that of the corresponding fraction of the non optically active model compound (B); (c) for fractions having high and comparable stereoregularity, the dipole moments are lower in the case of (A) and (B), in which the branched carbon atom of the side group is nearer to the main chain.

These data can be interpreted on the basis of the differences in conformational equilibria expected for the main chain of such polymers in solution.
Polymerization of methylphenylketone and its copolymerization with benzaldehyde
Authors: Tsunetsugu T. , Arimoto K. , Fueno T. , Furukawa J.
Published: April 2003

Methylphenylketene was polymerized by a variety of organometallic catalyst/solvent systems at −78 to −20°C. The polymer obtained was found to be exclusively polyster, in contrast to previous results which indicated that dimethylketene gave polyester, polyester, polyacetal, and polyketone, depending on the catalyst/solvent systems used.

Copolymerization of methylphenylketene with benzaldehyde led to the formation of a 1:1 copolymer. Hydrogenolysis of the copolymer showed that it was practically an alternating copolymer and that its structure was predominantly of the polyester type.

Both the homopolymer and copolymer have poor crystallinity as compared with those obtained from dimethylketene.
Asymmetric‐induction polymerization of β‐vinylacrylates
Authors: Tsunetsugu T. , Fueno T. , Furukawa J.
Published: April 2003

Optically active polymers of methyl, ethyl, n‐butyl, and tert‐butyl β‐vinylacrylates were synthesized by using optically active catalyst systems such as n‐BuLi/sodium l‐menthoxide and n‐BuLi/sodium d‐bornoxide. The optically active alkoxides were found to be even more efficient cocatalysts for the asymmetric‐induced polymerization than were the corresponding ethers.

The polymers obtained were characterized from their optical rotatory dispersion curves and infrared absorption spectra.
Aqueous polymerization of acrylic acid initiated by KMnO4 — H2C2O4 redox system
Authors: Misra G. S. , Narain Harish
Published: April 2003

Polymerization of acrylic acid in aqueous solution initiated by permanganate‐oxalic acid redox pair has been studied at 32 ± 0.2°C in nitrogen atmosphere. The rate of polymerization has been found to be nearly independent of oxalic acid concentration within the range 1.87 to 9.33 · 10−3 mole/l. and decreases only at higher concentrations of the oxalic acid. The rate has also been found to vary with the first power of the monomer concentration (within the range 1.44 to 5.76 · 10−2 mole/l.) and the first power of the catalyst concentration (8.0 to 28.0 · 10−5 Mole/l.). It is, however, proportional to half power at relatively high catalyst concentration, at fixed concentrations of oxalic acid (1.03 · 10−2 mole/l.) and the monomer (5.76 · 10−2 mole/l.). At higher concentration of monomer the catalyst exponent has been found to be nearly unity for both the higher and lower concentrations of the catalyst. The initial rate of polymerization increases with increase in temperature. The overall energy of activation has been found to be 19.56 kcal/mole within the temperature range 30 – 45°C. Organic solvents and salts (KCI, Na2SO4, and Na2C2O4) depress the rate but MnSO4 4H2O has been found to increase the initial rate but depress the maximum conversion.
Quantitative IR‐spektroskopische untersuchungen zur temperaturabhängigkeit der CCl‐streckschwingungen von polyvinylchlorid
Authors: Pohl Von H. U. , Hummel D. O.
Published: April 2003

Vinylchlorid wurde bei verschiedenen Temperaturen strahlenchemisch in Masse polymerisiert; die Polymeren wurden bei Meßtemperaturen zwischen 30 und 200°C IR‐spektroskopisch untersucht. Es wird ein Verfahren angegeben, Komplexe, überlagerter Absorptionsbanden graphisch aufzutrennen. Der Komplex der ν(CCI)‐Schwingungen wurde in 7 Banden bei 603, 613, 624, 636, 647, 677 und 696 cm−1aufgelöst. Die Temperaturabhängigkeit der relativen integralen Extinktion dieser Banden wurde gemessen; die Zuordnung zu bestimmten Konfigurationen und Konformationen wird diskutiert.
Polyoxymethylene single crystals. II. The effect of substrate on annealing behavior
Authors: Garber C. A. , Geil P. H.
Published: April 2003

The annealing behavior of polyoxymethylene single crystals has been studied at various temperatures on five different substrates. Crystals were found to anneal faster on high energy substrates (mica, aluminum, NaCl) than on low energy substrates (polyethylene terephthalate and glass). These observations suggest the presence of interactions between substrate and folds.
Thermodynamisches verhalten, expansionskoeffizient und viskositätszahl von polystyrol in tetrahydrofuran
Authors: Schulz Von G. V. , Baumann H.
Published: April 2003

Streulichtmessungen ergeben, daß Polystyrollösungen in Tetrahydrofaran stark exothermisch sind; der 2. Virialkoeffizient des osmotischen Druckes A2 wird überwiegend durch den Enthalpieterm A2,H bestimmt. Der Expansionskoeffizient gehorcht der (α5−α3)‐Beziehung mit der Konstante von STOCKMAYER und die h(z̄)‐Funktion der Gleichung von CASASSA. Die Viskositätszahl [η] wird durch die Gleichung von KURATA und YAMAKAWA erfaßt. Mit den drei Parametern β/M, K0 = r̄/M und b/M (b = hydrodynamischer Durchmesser) lassen sich A2, α, [η] und der Trägheitsradius r̄ über einen großen Molekulargewichts‐bereich in guter Übereinstimmung mit den Meßwerten berechnen (vgl. Abb. 3).
Effects of radiation on styrene and α‐methyl styrene in different organic solvents and in the pure state. A study by pulse radiolysis
Authors: Schneider Christel , Swallow A. J.
Published: April 2003

Styrene and α‐methyl styrene, both in solution in organic solvents and in the pure state, have been subjected to 2 μ sec pulses of 4 MeV electrons. The absorption spectra of the transient intermediates formed have been measured and kinetic studies have been carried out. The results for styrene were similar to those for α‐methyl styrene. In the case of solutions of styrene in cyclohexane, transients absorbing at 320 mμ and 390 mμ were seen. The absorption at 320 mn is attributed in part to a slowly disappearing polymer radical with a structure resembling benzyl. The absorption at 390 mn disappears rapidly and is attributed to a radical anion. Various additives interfere with its formation. The effect of styrene concentration and dose rate on the formation of the transients is reported. Styrene reacts rapidly with solvated electrons in methanol, but the anion formed becomes proton‐ated rapidly. In benzene the absorption appears at a wavelength similar to that seen with pure benzene. Intense absorptions at 290 mμ and 320 mμ are seen in carbon tetrachloride solution. Absorptions at ∼320 mμ and ∼400 mμ are seen when pure styrene or α‐methyl styrene are pulsed. A stable species absorbing at 320 mμ is also present. Values for rate constants are compared with those obtained from measurements of polymer formation.
Ein perlförmiges cellulosegel für die chromatographie
Authors: Determann Von Helmut , Rehner Helmut , Mitarbeit Theodor Wieland , Meyer von Norbert , Wente Frank
Published: April 2003

Durch Ausfällen mit organischen Säuren lassen sich aus verschiedenen in Benzol emulgierten Celluloselösungen mechanisch und chemisch widerstandsfähige Perlen von 30 bis 300 μm Durchmesser gewinnen. Sie haben Poren von durchschnittlich einigen hundert nm Weite, deren mittlerer Durchmesser von der Cellulosekonzentration in der Lösung abhängt. Hauptsächlich wurden die Gele aus 2, 6 und 10% cellulosehaltiger SCHWEIZER‐Lösung, welche mit benzolischer Benzoesäure regeneriert waren, in ihrer Fähigkeit zur gelchromatographischen Trennung von E.coli‐Bakterien, Dextranen der Molgewichte von 2·105 bis 7·106, verschiedenen Proteinen und Benzylalkohol im. wäßrigen System untersucht. Besonders die aus 6‐ und aus 10‐proz. Lösung erhaltenen Gelperlen eignen sich zur Trennung von Substanzen im Molekulargewichtsbereich von 104 bis 107. Die hygroskopische Essigsäure, statt Benzoesäure als Fällungsmittel bewirkt eine Schrumpfung, d.h. Porenverengung in der Nähe der Oberfläche.
Solid state polymerization of zinc methacrylate
Authors: Parrish C. F. , Kochanny G. L.
Published: April 2003

Zinc methacrylate has been polymerized in the solid state by the post‐irradiation technique at 89.5°C. The polymer produced was less isotactic than that obtained from barium methacrylate dihydrate when polymerized under similar conditions. The tacticity of the poly(zinc methacrylate) differed markedly from the polymer produced in the liquid phase from methyl methacrylate or methacrylic acid. X‐ray studies of the zinc methacrylate showed the monomer to have an orthorhombic unit cell with lattice constants of a = 17.94Å, b = 9.16 Å, and c = 13.2 Å. There are 8 molecules per unit cell and the symmetry can be classified as either Pnam or Pna2. The anhydrous monomer shows pronounced thermal polymerization at 89.5°C and the radiation‐induced reaction shows no measurable intensity dependency over a 6 fold change in dose rate.
Application of the FLORY‐FOX‐SCHAEFGENintrinsic viscosity molecular weight relation to high polymers
Authors: Patel J. R. , Patel C. K. , Patel R. D.
Published: April 2003

The relationship for the determination of unperturbed dimensions, as proposed by FLORY‐FOX‐SCHAEFGEN, has been found to be inapplicable to many polymer‐solvent systems. However, while plotting [η]2/3/M1/3vs. M/[η] for different solvents a common point of intersection which is not on the ordinate has been observed in all the cases. Unperturbed dimensions obtained from this point have been found to agree with those derived by using other methods.
A semi‐quantitative investigation of the cysteic acid‐containing peptides in a partial acid hydrolysate of γ‐keratose
Authors: Asquith Raymond Smith , Shaw Trevor
Published: April 2003

γ‐Keratose, a soluble fraction of peracetic acid oxidised wool has been partially hydrolysed with 5 N hydrochloric acid under controlled conditions. The mixture of low molecular weight peptides has been separated into two fractions. The cysteic acid rich fraction contained 2750 μtmole/g of peptide‐bound cysteic acid. This accounts for 58% of the total cysteic acid present in γ‐keratose. The structures of a number of the cysteic acid peptides in this fraction have been deduced, and their amounts estimated on a semi‐quantitative basis. The following peptides have been identified and are listed in descending order of quantity present: Ser‐CySO3H.CySO3H.; Thr.CySO3H.CySO3H.; Gly.CySO3H.CySO3H.; CySO3H.;CySO3H.; CySO3H.Glu; Pro.CySO3H.CySO3H.; (Arg,CySO3H,CySO3H); Val‐(CySO3H)1–2. Without correction for losses during separation and analysis of the peptides it has been shown that at least 10.1% of the cysteic acid in γ‐keratose occurs in the sequence –CySO3H.CySO3H–. If a correction factor based on the recovery of cysteic acid from the analytical procedure is applied, then this sequence accounts for a minimum of 31.7% of the cysteic acid. Some consequences of a high incidence of this sequence are considered.
Polymerization and copolymerization of allyl ethenesulfonate
Authors: De Witte E. , Goethals E. J.
Published: April 2003

Allyl ethenesulfonate (AES) has been polymerized by radical initiators under different conditions. The polymers consist of 67 to 86% of cyclic recurring units for monomer concentrations going from 8.9 (bulk) to 0.28 mole·1−1. The amount of allyl groups taking part in the polymerization is much higher than expected from the composition of copolymers obtained from propyl ethenesulfonate and allyl ethanesulfonate. The allyl group of AES is incorporated in the polymer chain only via the cyclopolymerization mechanism.

AES has been copolymerized with styrene, methyl acrylate, and vinyl acetate. The folowing copolymerization parameters were found:

The percentage of cyclic recurring units is low in copolymers with methyl acrylate and with styrene but is high in those with vinyl acetate. In the copolymerization with styrene and with methyl acrylate the reactivity of AES is about equal to that of butyl thenesulfonate; in the copolymerization with vinyl acetate it shows a much higher reactivity than butyl ethenesulfonate. This increase in reactivity is attributed to the formation of cyclic radicals. AES is another example of an unsymmetrical 1.6‐diene wherein the reactivity of the less reactive double bond is greater than that observed in analogous monomers where only that double bond is present.
Predictions of polymer molecular weights from the theory of emulsion polymerization
Authors: Watterson J. G. , Parts A. G. , Moore D. E.
Published: April 2003

The theory of HARKINS, SMITH and EWART, describing the formation of latex particles in the emulsion polymerization system is used, to describe the average degree of polymerization of the formed polymer. Transfer reactions are assumed to be negligible. The average lifetime t̄ of growing polymer radicals – to which the average degree of polymerization is proportional – is found to be

where x = ρt/N is the dimensionless variable representing the average number of radicals created per latex particles by time t. ρ is the constant rate of production of radicals, N is the number of latex particles at the time of disappearance of micelles.
Studies on the polymerization of bifunctional monomers. XV. Anionic polymerization of o‐divinlbenzene
Authors: Aso Chuji , Kunitake Toyoki , Imaizumi Yoji
Published: April 2003

Anionic polymerization of o‐divinylbenzene was carried out with organolithium and alkalimetal‐naphthalene catalysts. The extent of cyclization in polymer was generally smaller than in cationic polymerization. The influence of the counter cation and of the solvent on the cyclization constant, rc, observed in polymerization with alkalimetal‐naphthalene catalysts agreed qualitatively with that on the rate of anionic propagation of styrene in the same system, if rc was considered to increase with the reactivity of the uncyclized anion.

In the sodium naphthalene/THF system, rc decreased on addition of NaBPh4 and this result was considered to indicate the free‐anion propagation. In the same system, the apparent difference in activation energy between intramolecular cyclization and intermolecular propagation was 2–3 kcal·mole−1.
Gel/water relationships in hydrophilic polymers: Nuclear magnetic resonance
Authors: Sterling Clarence , Masuzawa Mitsunobu
Published: April 2003

The spectra of nuclear magnetic resonance were recorded and analyzed for different concentrations of gels of agar, carboxymethyl cellulose, gelatin, and starch. The line width of the signal of the hydroxyl proton broadens with increasing concentration of polymer, and the signal height continually decreases. A small paramagnetic shift also occurs. Changes in signal areas are interpreted in terms of “solid”, “bound”, and “free” water, with no “solid” water found in gels of gelatin and starch. Free water decreases continuously with increasing concentration in all gels. The very great line‐broadening for low concentrations of agar gels is explained by the water‐organizing effect of the D‐galactopyranose moiety.
The reaction of propane sultone with macromolecules. II. Poly(vinyl alcohol)
Authors: Goethals Eric J. , Natus Guy
Published: April 2003

The sulfopropylation of poly(vinyl alcohol) (PVA) with propane sultone under different conditions has been studied. Attempts to carry out the reaction via the sodium alcoholate of PVA, prepared by different methods, failed, gave low yields or resulted in the formation of insoluble reaction products. The best way to obtain sulfopropyl poly(vinyl alcohol) (SPPVA) was to react propane sultone with PVA dissolved in dimethyl sulfoxide (DMSO) in the presence of potassium carbonate. Most probably the reaction occurs via dimethyl‐(3‐sulfopropoxy)sulfonium salt which is formed by reaction of propane sultone with DMSO. By passing a solution of the potassium salt of SPPVA through an acidified ion exchange column the free acid was obtained. Both the potassium salts and the free acids were hygroscopic, water‐soluble substances showing typical polyelectrolyte properties.
Formaldehyde resins. 94. On the reaction products of diphenyl ether and polymetylenediphenyl ethers with formaldehyde
Authors: Ninagawa Akira , Imoto Minoru
Published: April 2003

From the reaction products of diphenyl ether and formaldehyde, o‐methylol diphenyl ether (o‐MMP) was isolated. Its amount was only 1/38 of that of p‐methylol diphenyl ether, as shown by v.p.c. The reaction of p.p′‐Diphenoxydiphenylmethane (M2P) and p.p′‐di‐(p″‐phenoxybenzyl)‐diphenyl ether (2M3P) with formaldehyde was also carried out in the presence of acidic catalysts in order to isolate the p‐monomethylol derivatives of M2P and 2M3P (p‐MM‐M2P and p‐MM‐2M3P) and p.p′‐dimethylol‐M2P (p.p′‐DM‐M2P).
Studies on the polymerization of bifunctional monomers. XVII. Cyclopolymerization of malealdehyde and the structure of the polymer
Authors: Aso Chuji , Kunitake Toyoki , Miura Masanobu , Kōyama Katsuhisa
Published: April 2003

Polymerizations of malealdehyde were carried out with alkalimetal alkoxides, AlEt3, pyridine, AlEt3TiCl4 and BF3OEt2 as catalysts. All the polymers obtained with other catalysts than AlEt3 and AlEt3TiCl4 were composed only of the cyclized unit (dialkoxydihydrofuran ring) (> 95%) and the 1.2‐addition structure (< 5%). IR spectra of the polymers obtained with AlEt3 and AlEt3TiCl4 catalysts were suggestive of the presence of five‐membered lactone rings which may occur as a result of termination by hydride transfer. The steric structure (cis vs. trans) of the dialkoxydihydrofuran ring in polymer was inferred from the comparison of the IR spectra of the polymer with those of the isomeric dialkoxydihydrofurans in the 800 cm−1 region. Anionic catalysts gave higher contents of the cis configuration, while coordinated anionic catalysts gave comparable amounts of the cis and trans structures.
Zur wechselseitigen löslichkeitsbeeinflussung von polymeren mit versehiedenen molekulargewichten
Authors: Breitenbach Von J. W. , Wolf B. A.
Published: April 2003

Die Trübungskurven für Lösungen von Mischungen aus gleichen Gewichtsanteilen einer Polystyrolprobe mit „wahrscheinlichster”︁ Molekulargewichtsverteilung (Pn = 3100) und eines Polystyrols mit relativ enger Molekulargewichtsverteilung (Pn = 800) in einem einfachen Lösungsmittel (Cyclohexan) und einem. Mischlösungsmittel (Benzol/Methanol im Vol.‐Verhältnis 3:1) wurden mit den Trübungskurven der Komponenten verglichen. Im Mischlösungsmittel nimmt im gesamten experimentell zugänglichen Konzentrationsbereich die Trübungstemperatur mit der Konzentration monoton zu; die Trübungskurve erstreckt sich hier über ein wesentlich größeres Temperaturgebiet als in Cyclohexan als Lösungsmittel.

Sowohl in Cyclohexan als auch im Lösungsmittel/Fällungsmittel‐Gemisch liegen die Trübungstemperaturen der Polymermischung bei einer bestimmten Gesamtpolymerkonzentration zwischen den Trübungstemperaturen der Lösungen der Komponenten derselben Konzentration. Durch Vergleich der Trübungskurven bei den entsprechenden Partialkonzentrationen der Polymermischung erkennt man jedoch, daß im Falle von Cyclohexan die langkettigen Homologen von den kurzkettigen in Lösung gehalten werden und umgekehrt, während im Mischlösungsmittel jeder Polymerzusatz unabhängig von seiner Kettenlänge die Löslichkeit herabsetzt.

Die beobachteten Unterschiede im Entmischungsverhalten von Polymerlösungen im Ein‐ bzw. Zweikomponentenlösungsmittel werden auf die bevorzugte Aufnahme der Lösungsmittelkomponente des Mischlösungsmittels ins Knäuelinnere zurückgeführt.
Kinetic studies on the polymerization of 1.3‐dioxolane catalyzed by triethyl oxonium tetrafluoroborate
Authors: Yamashita Yuya , Okada Masahiko , Kasahara Hideo
Published: April 2003

The kinetics of the polymerization of 1.3‐dioxolane with triethyl oxonium tetrafluoroborate has been studied in methylene chloride solution. The polymerization was preceded by an induction period. The addition of water to the system prolonged the induction period and decreased both rate of polymerization and molecular weight of the polymer. The induction period was found to be proportional to reciprocal of the initial catalyst concentration but to be independent of initial monomer concentration. Therefore it would appear that the induction period is mainly due to a reaction of the catalyst with water. A near linear relationship between the degree of polymerization and the conversion suggested that the polymerization proceeds essentially without termination and chain transfer reactions to an equilibrium conversion in the absence of water. The rate constant of propagation was estimated to be 4.3·10−2l./ mole sec in methylene chloride at 30°C.
Kinetic studies in ethylene polymerization with ziegler type catalysts. VI. Characterization of catalyst sites by polymerization experiments in the presence of deuterium
Authors: Schindler A.
Published: April 2003

Ethylene polymerization in the presence of deuterium was investigated with the four catalyst systems resulting from Et3Al and Et2AlCl in combination with either TiCl4 or TiCl3. From the effect of catalyst ratio on the kind and the amount of deuterated products formed the existence of three kinds of titanium sites could be inferred. An H, D‐exchange reaction involving the β‐hydrogen of the growing chain was found to be characteristic for chain growth on Ti(IV) sites. The inactivity of BuLi or Et2Zn systems in such exchange reactions implied the existence of bimetallic complexes in alkylaluminum systems. The exclusive formation of CH2D groups in the polymer by a transfer reaction was found to be characteristic for chain growth on Ti(III) sites. The occurrence of an H,D‐exchange reaction involving the monomer and the formaiton of deuterated ethanes was assigned to the presence of polymerization‐inactive titanium hydride sites, formed at high catalyst ratios.
Phase changes in polyethylene single crystals. The effects of thermal stress and electron irradiation
Authors: Kiho H. , Ingram P.
Published: April 2003

Single crystals of polyethylene have been reported to undergo a crystallographic phase change from an orthorhombic unit cell to monoclinic when heated to temperatures near their original crystallization temperatures. This change is shown to be due purely to thermal stresses set up between the crystals and substrate on which they lie, arising from a difference in expansion coefficients of crystals and substrate. The orientation of the monoclinic lattice with respect to the orthorhombic lattice is consistent with an effective deformation parallel to the orthorhombic b‐axis. At temperatures above 110°C the monoclinic phase relaxes almost completely back to orthorhombic primarily through the greatly increased mobility of the chains in their folded portions. The effects of an electron beam on the polyethylene crystal lattice have been studied by electron diffraction during irradiation at temperatures from −161 to + 110°C. The changes in dimensions of the unit (sub)‐cell were determined as functions of the time of irradiation. Above about 30°C a stable hexagonal phase is formed before the crystalline diffraction pattern degrades to a diffuse halo. This change is ascribed to (i) a depression of a transition temperature (due to defects) analogous to that found in n‐paraffins when the orthorhombic unit cell becomes hexagonal, and (ii) elastic distortions around the lattice defects. It is also noted that the transformation proceeds readily at 110°C in the absence of radiation if a small dose is given initially: the number of defects under these conditions are few and consequently on cooling to room temperature the hexagonal and orthorhombic phase co‐exist. Although no definitive conclusions as to the nature of the reaction can be determined, the evidence is that the defects are primarily scissions and cross‐links in the crystal lattice.
Morphology and growth of extended chain crystals of polyethylene
Authors: Wunderlich Bernhard , Mielillo Louis
Published: April 2003

The morphology and growth of extended chain crystals of polyethylene is discussed on the basis of optical and electron microscopy. The spherulitic habit is shown to be caused by nucleation of new lamellae on the (001) surface of lamellae, branching of lamellae on their growth face, and thickening of lamellae. Spherulite centers have been identified down to the primary lamella. Analysis of intersections of lamellae during crystallization allowed the identification of intermediate stages of crystal growth. Fracture surfaces parallel to the growth face and the (001) face are discussed. “Ripple decoration” by surface recrystallization is developed as a tool for fracture surface study. Kink bands are described as growth defects. Bending of lamellae is shown to go by slip parallel to the polymer chains. Ripple and drawn out fiber annealing is analyzed. All observations on extended chain crystals are used to propose a mechanism of extended chain crystal growth of polyethylene under elevated pressur.
Statistical thermodynamics of polymer crystallization
Authors: Peterson J. M. , Lindenmyer P. H.
Published: April 2003

A model has been assumed in which 1. chain folding if it occurs at all, is regular, 2. chain ends do not enter the crystal, and 3. no fractionation takes place except the rejection of all molecules from the crystal whose lengths are shorter than the crystal thickness. According to this model it is shown that the entropy contribution of the non‐crystalline sections of a partially crystallized chain is roughly constant per molecule and is inconsequential relative to the free energy of crystallization. By assuming a molecular weight distribution function and using polyethylene as an example, the free energy vs. crystal thickness shows a minimum. The crystal thickness predicted by this minimum is in reasonable agreement with observations and the predicted temperature and molecular weight variations are qualitatively in agreement with experiment.
Reversible long period variations with temperature in single crystals of branch‐containing polyethylenes
Authors: Dawkins J. V. , Holdsworth P. J. , Keller A.
Published: April 2003

The variation with temperature of the small‐angle X‐ray diffraction patterns from annealed single crystal mats of linear polyethylene and a number of branched polyethylenes has been examined. On cycling the temperature between room temperature and the annealing temperature the intensities of the small‐angle reflections of all the samples were observed to change reversibly. However, in the case of the branched polyethylene mats, these changes were accompanied by significant reversible changes in the X‐ray long periods. These reversible long period changes were attributed to reversible changes in the thickness of the lamellar crystals of which the mats were composed. Possible explanations for this behaviour, and its significance to existing ideas of polymer crystallization, are briefly discussed.
Etude par diffusion de la lumière des hétérogéneités rencontrées dans les solutions de polyoxyéthylène
Authors: Strazielle Par Claude
Published: April 2003

Nous avons étudié par diffusion de la lumière un certain nombre d'échantillons de polyoxyéthylène de masses moléculaires comprises entre 10.000 et 350.000.

Suivant les conditions expérimentales adoptées, les intensités diffusées peuvent ětre perturbées par des hétérogénéités.

Nous avons mis en évidence la formation de cristaux lorsque les solutions sout filtrées sur des filtres fins à 25°C, ils sont peu résistants et disparaissent à 40°C.

Pour les échantillons de masses moléculaires élevées, les solutions contiennent une partie hétérogène qui résiste à des températures supérieures à la températur de fusion du Polymère, mais les agrégats sont éliminés par filtration.

Nous avons enfin étudié la diffusion due à la partie hétérogène afin d'obtenir certaians renseignements comme le pourcentage et les dimensions des agrégats ou des cristaux en solution.
Aqueous polymerization of acrylamide initiated by permanganate/oxalic acid redox system
Authors: Misra G. S. , Shukla J. S. , Narain Harish
Published: April 2003

The polymerization of acrylamide initiated by permanganate/oxalic acid redox pair has been studied in aqueous media at 35 ± 0.2°C in nitrogen atmosphere.

The rate of polymerization is independent of activator (oxalic acid) concentration (0.75·10−3 to 7.5·10−3 mole/l.) except at very high (above 7.5·10−3 mole/l.) or very low (below 0.75·10−3 mole/l.) concentrations of the activator. The rate varies linearly at low monomer concentration. The catalyst exponent decreases from nearly unity to 0.65 with the increase in the concentration of catalyst (KMnO4) probably due to participation of primary radicals in the termination of the growing chain.

The initial rate increases with increase in the polymerization temperature. The overall energy of activation has been found to be 11.97 Kcal/mole within the temperature range 25‐50°C.

Organic solvents (water miscible only) and salts (KCI, Na2SO4) depress the initial rate but small amounts of manganous salts (MnSO4) can increase the initial rate to a considerable extent. High concentration of salts (Na2SO4, KCl, and MnSO4) causes termination of the growing chain. A complexing agent, NaF, decreases the initial rate but the limiting conversion is increased.

Introduction of new catalyst at intermediate stages of polymerization increases both the rate and the limiting conversion.
Kinetics of the formation of cellulose xanthate in homogeneous medium
Authors: Andersson Lennart , Samuelson Olof , Törnell Bertil
Published: April 2003

The total rate of xanthation of low molecular weight cellulose in a homogeneous medium was studied spectrophotometrically using a stopped flow technique. By combining these results with determinations of the number of primary and secondary xanthate groups, the individual rate constants for the formation of these groups were calculated.

The results show that the xanthate formation is a second order reaction determined by the concentrations of carbon disulfide and alcoholate.
Vinylpolymerisation. 216. Mitt. polmerisation von methylencycloalkanen
Authors: Takemoto Von Kiichi , Izubayashi Masuji , Imoto Minoru
Published: April 2003

Die Polymerisation sowie due Copolymerisation von Methylencyclobutan, ‐cyclopentan und ‐cyclohexan wurden untev verschiedenen Bedingungen untersucht. Es ergab sich, daß Methylencycloalkane nicht homopolymerisieren, aber radikalisch mit einigen Vinylmonomeren ziemlich leicht copolymerisiert werden können. Die Aktivierungsenergien sowieentropien bei der Copymermerisation von Methylencycloalkanen wurden ermittelt.
Studies on new chemical resistant polyesters based on bisphenol‐a derivatives
Authors: Gupta S. K. , Sharma Y. N. , Thampy R. T.
Published: April 2003

Bisphenol‐A (I), 2.2‐di(4‐hydroxy‐3.5‐dibromophenyl)‐propane(IA) and 2.2‐di(4‐hydroxy‐3.5‐dichlorophenyl)‐propane(IB) were condensed with methyl chloroacetate to give isopropylidene bis(p‐phenyleneoxy)‐di‐methyl acetate (II) and its bromo‐ (IIA) and chloro‐ (IIB) derivatives, respectively. Based on compounds II, IIA, and IIB, three new polyesters were synthesised. These polyesters were evaluated for hydrolytic stability, heat distortion point, vicat needle point, flame resistance, and thermogravimetric analysis. They have vicat needle points comparable with hexachloro‐endo‐methylene tetrahydrophthalic acid (HET) based polyester. Resins based on IIA and IIB have 20 times better hydrolytic stability than HET isophthalate resin. Thermogravimetric analysis showed that resin based on compound II has highest 50% decomposition temperature out of these polyester resins.
Synthese und halbleitereigenschaften einiger komplexe und der aus ihnen hergestellten polymeren. Teil 2. Polymere mit phthalocyaninartiger und triazinartiger stuktur
Authors: Manecke Von Georg , Wöhrle Dieter
Published: April 2003

Polymere mit phthalocyaninrtiger Struktur ergaben sich durch Reaktion von einigen schwefelhaltigen Komplexen, die vier Nitrilgruppen enthalten, mit Kupferacetylacetonat bei höherer Temperature. Die Leitfähigkeiten der Polymeren liegen zwischem 6,3·10−3 und 2,1·10−10 Ohm−1cm−1. Die Aktivierungsenergie zeigt Werte mit einer unteren Grenze von 0,04 eV. Durch Erhitzen einiger Tetracyanverbindungen in Chinolin wurden Polymere mit triazinartiger Struktur erhalten, die Leitfähigkeiten bis zu 3,9·10−2 Ohm−1cm−1 aufweisen.
Unterschiedlicher verlauf der phosphorolytischen amylosesynthese mit maltotriose und höheren maltodextrinen als starter
Authors: Pfannemüller Von B. , Burchard W.
Published: April 2003

Das unterschiedliche Starterverhalten von Maltotriose einerseits und Maltotetraose und Maltohexaose andererseits bei der Synthese von Amylosen durch Kartoffelphosphorylase wird untersucht. Die Synthese verläuft in jedem Fall nach einem Mehrkettenmechanismus. Mit Maltotetraose und Maltohexaose als Starter werden Amylosen mit einer POISSON‐Verteilung synthetisiert. Die mit Maltotriose als Starter synthetisierten Amylosen setzen sich degegen aus einem einheitlichen, hochmolekularen Anteil und einem uneinheitlichen, niedermolekularen Anteil zusammen. Es wird gezeigt, daß die Unterschiede in der Molekulargewichtsverteilung darauf beruhen, daß bei Synthesen mit Maltotriose für die Startreaktion eine 400 mal kleinere Geschwindigkeit gefunden wird als für die Wachstumsreaktion, während bei Synthesen mit Maltotetraose und Maltohexaose Start‐ und Wachstumsreaktion gleiche Geschwindigkeit besitzen.
Penultimate unit effect in the copolymerization of alkyl methacrylates and styrene
Authors: Chaudhuri Ajit Kumar , Palit Santi R.
Published: April 2003

Kinetics of bulk copolymerization of styrene and alkyl methacrylates, namely, ethyl, isobutyl and n‐nonyl methacrylate have been investigated at 60°C, and the extent of diffusion‐controlled termination in these systems has also been checked. Rate‐composition curves reveal that addition of a small amount of styrene in pure alkyl methacrylates markedly reduces the rate of polymerization, the effect becoming more important as the chain length of the ester group is increased. With higher alkyl methacrylates, the position of the minima in the curves shifts towards a lower concentration of styrene in the feed. The applicability of ARLMAN'S theory on the variation of the Φ‐factor with monomer feed composition has been examined.
Studies on amylose and its derivatives. Part VII. Melting and glass transition temperatures of amylose esters
Authors: Cowie J. M. G. , Toporowski P. M. , Costaschuk F.
Published: April 2003

Various amylose esters ranging from the acetate to the caproate were prepared. Melting and glass transition temperatures were measured for each and it was observed that both Tm and Tg were depressed as the chain length of the substituted ester side chain was increased. By assuming this to be an internal plasticization process, estimates of Tm ≃ 800°K and Tg ≃ 590°K were obtained for the unsubstituted amylose molecule. An average value of (Tg/Tm) of 0.80 was calculated for these esters which would suggest that they are moderately rigid, unsymmetrical polymers.
Über wasserstofffbrücken in polyamiden
Authors: Bessler Von Eberhard , Bier Gerhard
Published: April 2003

Die Temperaturabhängigkeit der IR‐Spektren verschiedener Polyamide im Gebiet der NH‐Valenzschwingen wurde im Temperaturbereich zwischen 25 und 250°C untersucht. In weitgehender übereinstimmung mit anderen Autoren wurde gefunden, daß bei teilkristallinen Polyamiden der relative Anteil der nicht über Wasserstoffbrücken gebundenen NH‐Gruppen unterhalb deren Schmelzpunkt unerheblich ist (unter 1%). In der Nähe des Schmelzpunktes nimmt der Anteil der freien Amidgruppen jedoch sprunghaft zu. Bei zwei amorphen Polyamiden aus Terephthalsäure und verzeigten Diaminen wurde bei Zimmertemperatur ein wesentlich höherer Anteil von freien NH‐Gruppen gefunden (mehrere Prozent) als bei den teilkristallinen aliphatischen Polyamiden. Bei den beiden amorphen Polyamiden ändert sich der relative Anteil freier NH‐Gruppen im untersuchten Temperaturbereich annähernd linear mit der Temperatur, wobei die Zunahme über der Glastemperatur stärker ist als unter der Glastemperatur. Bei höheren Temperaturen (gemessen 230°C) wird für alle untersuchten Polyamide ein Anteil freier NH‐Gruppen von 10–20% abgeschätzt.
Synthesis of mixed polysaccharides based on cellulose
Authors: Gal'braikh L. S. , Rogovin Z. A. , Belyakova M. K. , Polukhina S. I.
Published: April 2003

The alkaline saponification of cellulose tosylates containing the tosyloxy group at various carbon atoms of the basic unit has been studied. It has been found that this reaction leads to the formation of mixed polysaccharides containing 2.3‐ and 3.6‐anhydrorings. The monosaccharide composition of mixed polysaccharides which are anhy droderivatives of cellulose has been determined.

The stereochemistry of the opening of α‐oxide rings in 2.3‐anhydroderivatives of cellulose has been considered. It is shown that the opening of 2.3‐anhydrorings by acidic and basic reagents takes place under predominant formation of basic units with altro‐configuration of the substituents on secondary carbon atoms.

An investigation has been carried out with respect to the reaction of 2(3)‐O‐tosylcellulose with ammonia in methanol and DMF and with potassium acetate in phenol. It has been established that these reactions proceed through the intermediate stage of the formation of 2.3‐anhydrorings. The synthesis of mixed polysaccharides with glucose, 3‐aminoaltrose, and 2‐aminoglucose on the one hand and with altrose and glucose as basic units on the other hand is described.

By the reaction of mesylcellulose with potassium acetate in phenol the synthesis of mixed polysaccharides with gluco‐ and mannopyranose units has been realized.
The influence of chain transfer agents on rate of polymerization in the heterogeneous and homogeneous polymerization of vinyl chloride
Authors: Breitenbach J. W. , Olaj O. F. , Reif H. , Schindler A.
Published: April 2003

The addition of small amounts of effective chain transfer agents such as carbon tetrabromide and dodecyl mercaptane to the azo‐iso‐butyronitrile‐initiated polymerization of vinyl chloride in 1.2‐dichloroethane leads to a marked increase in the rate of polymerization which, although lesser than in the heterogeneous bulk polymerization of vinyl chloride, amounts to approximately 20% in this completely homogeneous system. At higher transfer agent concentrations due to the slightly retarding action of the transfer agent a decrease in rate is to be observed so that maximum rates are obtained with 3ċ10−4 moles of transfer agent per mole of monomer. As in the heterogeneous bulk polymerization the increase of rate is explained by a transformation of the less active radicals formed by chain transfer to monomer into the more active radicals derived from the chain transfer agent, leading to an increase in kinetic chain length. The influence of the chain transfer agent on the heterogeneous and homogeneous polymerization of vinyl chloride is compared and a kinetic scheme, which is representative for both cases, is established and discussed in detail.
Radiation induced solid state polymerization of derivatives of methacrylic acid. VI. Polymerization of barium methacrylate dihydrate during irradiation
Authors: Bowden M. J. , O'Donnell J. H. , Sothman R. D.
Published: April 2003

Crystalline barium methacrylate dihydrate polymerized during gamma irradiation at 15–35°C. Sigmoidal shaped conversion curves were obtained. The induction period decreased markedly with increase in temperature or dose rate. The polymerization rate(approximately constant from 25–75% conversion) increased with dose rate, corresponding to an exponent of about 0.5, but was almost independent of temperature. ESR spectra showed that the radical concentration increased linearly with time from the commencement of irradiation giving G(radicals) = 7.6 ± 0.5 at 25°C and the same value at 15°C. The radical concentration decreased during the polymerization period, but then increased again. The induction period was attributed to physical trapping of short‐chain propagating radicals.
Die radikalausbeute beim thermischen zerfall von azoisobuttersäuredinitril in gegenwart von sauerstoff und in methylmethacrylat als lösungsmittel
Authors: Vogt Von Walter , Dulog Lothar
Published: April 2003

Die Radikalausbeute, gekennzeichnet durch den Radikalausbeutefaktor ε (efficiency), beim thermischen Zerfall von Azoisobuttersäuredinitril (AIBN) in sauerstoffhaltigen Lösungen wurde mit Hilfe zweier direkter chemisch‐analytischer Methoden bestimmt, die sich gegenseitig ergänzen. Die 1. Methode beruht auf der gaschromatographischen Bestimmung des durch Kombination der primären 2‐Cyanoisopropylradikale entstehenden Tetramethylbernsteinsäuredinitrils; sie liefert einen Wert für (1‐ε). Die 2. Methode beruht auf der jodometrischen Bestimmung von 2‐Cyanoisopropylhydroperoxid und p‐Benzochinon, die letztlich durch eine Abfangreaktion mit Hydrochinon aus den der primären Kombination entgangenen Radikalen entstehen; sie liefert direkt einen Wert für ε. Nach beiden Methoden wurde übereinstimmend bei dem System Methylmethacrylat/AIBN/O2/Hydrochinon und bei 90°C ein Wert von ε + 0,810 ± 0,005 erhalten. Zwischen 70 und 100°C steigt ε dabei linear von 0,785 ± 0,005 auf 0,833 ± 0,005. Für n‐Propylacetat und Toluol als Lösungsmittel wurde bei 90°C der gleiche ε‐Wert wie für das Methylmethacrylat gefunden, nämlich 0,813 ± 0,005 und 0,810 ± 0,005.
Kinetik der äthylenpolymerisation mit löslichen Ziegler‐Nnatta‐katalysatoren
Authors: Reichert Von K. H. , Schubert E.
Published: April 2003

Es wird über die Kinetik der Polyreaktion von Äthylen und Äthylen‐d4 mit dem homogenen ZIEGLER‐NATTA‐Katalysator (C5H5)2TiCl2/Al(C2H5)2Cl und einigen seiner Homologen in Benzol als Lösungsmittel berichtet.

Hiernach ist die Polyreaktion des Äthylens als Nebenreaktion der Reaktionsfolge des Katalysatorsystems anzusehen und setzt sich aus einer Start‐, Wachstums‐, Abbruch‐ und Übertragungsreaktion zusammen. Die Geschwindigkeitskonstanten der Teilreaktionen für den homogenen und heterogenen Polymerisationsbereich werden angegeben. Für die miximale Bruttopolymerisationsgeschwindigkeit im heterogenen Bereich wurde folgende Abhängigkeit ermittelt:

Als polymerisationsaktive Spezies wird ein Titan(IV)‐Aluminium‐Komplex mit brükkenständiger Äthylgruppe vorgeschlagen. Wachstum soll hierbei nach erfolgter Aktivierung des Monomeren durch Insertion zwischen die im Komplex exo‐ständige Titan‐Kohlenstoffbindung vorsichgehen.