bluuebunny/crossref_metadata_2025 huggingface dataset:
Hormone replacement therapy and cancer risk: A systematic analysis from a network of case‐control studies
Authors: Fernandez Esteve , Gallus Silvano , Bosetti Cristina , Franceschi Silvia , Negri Eva , La Vecchia Carlo
Published: April 2003

To provide comprehensive and quantitative information on the benefits and risks of hormone replacement therapy (HRT) on several cancer sites, we systematically examined the relation between HRT use and the risk of various cancers in women aged 45–79 by using data from a framework of case‐control studies conducted in Italy between 1983 and 1999. The overall data set included the following incident, histologically confirmed neoplasms: oral cavity, pharynx, larynx and esophagus (n = 253), stomach (n = 258), colon (n = 886), rectum (n = 488), liver (n = 105), gallbladder (n = 31), pancreas (n = 122), breast (n = 4,713), endometrium (n = 704), ovary (n = 1,614), urinary bladder (n = 106), kidney (n = 102), thyroid (n = 65), Hodgkin's disease (n = 26), non‐Hodgkin's lymphomas (n = 145), multiple myeloma (n = 65) and sarcomas (n = 78). The control group comprised 6,976 women aged 45–79 years, admitted for a wide spectrum of acute, nonneoplastic conditions. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) for use of HRT were derived from multiple logistic regression equations. There was an inverse association between ever use of HRT and colon (OR = 0.7), rectum (OR = 0.5) and liver cancer (OR = 0.2), with a consistent pattern of protection for duration of use. An excess risk was found for gallbladder (OR = 3.2), breast (OR = 1.1), endometrial (OR = 3.0) and urinary bladder cancer (OR = 2.0). These data from a southern European population add some useful information on the risk‐benefit assessment of HRT among postmenopausal women. © 2003 Wiley‐Liss, Inc.
Über die konzentrationsabhängigkeit der viskositätszahl bei linearen und verzweigten makropolymeren. XII. Mitteilung über polyester
Authors: von Batzer Hans , Von Weissenberger Unter Mitarbeit G. , Lung M. , Lang H.
Published: April 2003

Lineare Polyester ergeben im untersuchten Bereich eine lineare Konzentrationsabhängigkeit von ηsp/c; bei verzweigten Polyestern zeigt sich eine andere Beziehung. Eine den verzweigten Polyestern analoge Konzentrationsabhängigkeit der Viskositätszahl ergab ein als verzweigt angesehenes Polyvinylchlorid, während ein anderes Muster dieses Polymerisates der Beziehung von Schulz‐Blaschke entspricht.
Über Perlpolymerisation
Authors: Trommsdorff von E.
Published: April 2003

Verteilt man in Wasser schwerlösliche Monomere durch mechanische Bewegung in Wasser, so bilden sich Tröpfchen. Durch Polymerisation der in Bewegung gehaltenen Tröpfechen kann man Polymerisatkugeln erhalten. Dieser Vorgang liegt der Perl‐ oder Suspensionspolymerisation zugrunde, die eine nicht geringe technische Bedeutung besitzt, bisher aber wissenschaftlich wenig bearbeitet ist. Reaktionskinetisch unterscheidet sich die Perlpolymerisation nicht von der Polymerisation des unverdünnten Monomeren. Sie ist zutreffend als „wassergekühlte Blockpolymerisation”︁ gekennzeichnet worden. Hinsichtlich des Reaktionsablaufs und der Art der Reaktionsprodukte unterscheidet sie sich von anderen in heterogener Phase in Wasser ablauenden Polymerisationsmethoden, nämlich der Emulsions‐, Dispersions‐ und Fällungspolymerisation. Die wäßrige Phase bei der Perlpolymerisation enthält Suspensionsstabilisatoren oder Verteilungsmittel. Diese haben die Aufgabe, das Ineinanderfließen der polymerisierenden Masse und das Verkleben der Polymerisatkügelchen zu verhindern. Die wichtigsten Verteilungsmittel sind: Wasserlösliche makromolekulare Verbindungen wie Gelatine, wasserlösliche Cellulose‐Derivate, Polyvinylalkohol, polyacrylsaure Salze sowie anorganische Pulver oder Niederschläge wie Talkum, Magnesiumcarbonat, Betonit, Calciumphosphat.

Die Verteiler dürfen die Grenzflächenspannung zwischen Wasser und Monomerem nicht stark heruntersetzen. Die Stabilität der Tröpfchen ist bei höherer Grenzflächenspannung groß, so daß sie sich ähnlich wie elastische Bälle verhalten.

Bei Erniedrigung der Grenzflächenspannung kommt es leicht zu Deformationen sowie einem Zusammenfließen der Tröpfchen. Die Wirkung der Suspensionsstabilisatoren beruht weiter auf der Stabilisierung der Wasserhaut zwischen den Tröpfchen, die sich nicht bis zur Berührung nähern können.

Vorstellungen dieser Art werden zur Verständlichmachung der Verteilerwirkung entwickelt und die bei der Perpolymerisation auftretenden Fehlermöglichkeiten diskutiert.
Action des solutions de soude sur les fibres de cellulose – equilibres de fixation de la soude – mercerisation
Authors: Chédin Par Jean , Marsaudon Andrée
Published: April 2003

On a étudié par voie chimique, en utilisant une méthode aussi rigoureuse que possible, la fixation de la soude sur la cellulose. On a aussi déterminé la quantité de soude fixée, et son hydratation, en fonction de la concentration des solutions sodiques. Une théorie d'ensemble a été ainsi élaborée, faisant intervenir les «hydrates» probables de la soude en solution, par l'intermédiaire d'équations d'équilibres. L'accessibilité des fibres natives dépend de la concentration des solutions de soude, et ce fait est aisément interprétable, qualitativement. Les fibres prélablement mercerisées, au contraire, semblent accessibles entièrement pour toutes les concentrations. Les conclusions rejoignent celles qui avaient été tirées à la suite d'un travail antérieur concernant l'action mercerisante des solutions aqueuses d'acide nitrique – un peu de cellulose ajoutée dans ces solutions (NO3H ou NaOH) joue un rôle analogue à un peu d'eau ajoutée (1OH actif par maillon C6), et les hydrates de soude ou d'acide nitrique, peuvent se constituer avec l'eau du mélange ou avec les OH cellulosiques.

La mercerisation de la cellulose est un phénomène analogue à l'interaction des hauts polymères polaires et de leurs solvants, plastifiants.
Determination of unsaturation in cyclized rubber using phenyl iododichloride
Authors: Rao N. V. C.
Published: April 2003

Unsaturation in cyclized rubber was estimated using phenyliododiochloride and the values obtained are in close agreement with the theoretical values predicated by Flory and Gordon. They are significantly different from those obtained by Van Veersen using hydrogen chloride, earlier described in the literature. This new method for determination unsaturation is simple and gives accurate results.
Light scattering and viscosity studies on some branched starch polymers
Authors: Stacy Carl J. , Foster Joseph F. , Erlander Stig N.
Published: April 2003

Preliminary studies are reported regarding the molecular weight of amylopectins and limit dextrins from various sources, using the light scattering method. Apparent molecular weights of all samples are in the millions, and centrifugation studies conclusively demonstrate that the high value determined by light scattering is not due to the presence of relatively insignificant percentages of undispersed material of much larger particle weight. One normal KOH was used as solvent. Since the possibility of air‐alkaline degradation exists using this solvent, some studies designed to determine the importance of this factor are reported. It was found that if air was excluded the particle weights remained in the millions for as long as 54 days, during which time the samples were degraded to less than one hundredth the original weight if air or pure oxygen were present. Further experiments demonstrated that the dispersions were stable during the time necessary for light scattering runs.

Intrinsic viscosity data on the amylopectins and their limit dextrins are reported. The intrinsic viscosity of a given amylopectin and the derived limit dextrin are very similar, and in general it is found that there is a very low positive dependence of intrinsic viscosity upon molecular weight for these materials, a result to be expected on the basis of the extensive branching.
Studies on the polymerization of bifunctional monomers. XI. The cyclic polymerization of divinyl ether and the structure of the polymer
Authors: Aso Chuji , Ushio Sunao , Sogabe Masateru
Published: April 2003

The radical polymerization of divinyl ether was further studied. In order to clarify the cyclic structure of poly (divinyl ether), the saponification and the oxidation of the polymer were studied.

While the conversion of the polymer to poly (vinyl acetate) was tried without sucess, about 1% of succinic acid was obtained by oxidation with nitric acid. This indicates the presence of head‐to‐head bonds in the polymer. Moreover, a bicyclic telomer composed of two moles of monomer and one mole of chloroform was obtained by the telomerization of divinyl ether in chloroform. The IR‐ and NMR‐spectra indicated the presence of a methyl group in that telomer. From these results, a structure containing bicyclic rings is sugessted for poly (divinyl ether) which was obtained by solution polymerization in benzene. This bicyclic ring is considered to have partly tail‐to‐tail addition and at least one five‐membered ring.
Chain transfer to ethers in the 3,3‐bis(chloromethyl)oxetane polymerization catalyzed by Al(iso‐C4H9)3
Authors: Penczek Irena , Sazanov Yurǐ N. , Penczek Stanislaw
Published: April 2003

In the polymerization of 3,3‐bis(chloromethyl)oxetane catalyzed by Aliso‐C4H9/water catalyst, according to the previously reported data (FURUKAWA, SAEGUSA et al.) insoluble polymers are formed. Although neither the exact mechanism of oxetanes polymerization in the presence of AIR3/H2O catalysts nor the nature of the insoluble polymers are known it is possible to use chain transfer agents to obtain perfectly soluble polymers. The addition of low molecular weight ethers (C2H5)2O, (n‐C4H9)2O, (Allyl)2O, 1,4‐dioxane, (β‐ClC2H4)2O, CH3OPh, and (C6H5)2O in low concentrations leads to the formation of soluble polymers with a very large range of mol. wts. (up to 106). The chain transferabilities of ethers increase with their proton‐attracting powers (basicity). In the presence of a chain transfer agent the kinetics of polymerization virtually changes. On the basis of the discussion of the general kinetic behaviors of the system and the dependence of D̄P̄ on conversion it was deduced that in this type of polymerization long living species are formed.
Syntheses of some polymers containing cyclopropane rings in the main chain. III
Authors: Oku Akira , Shono Tatsuya , Oda Ryohei
Published: April 2003

Some poly (5‐iminohydantoins) containing a cyclopropane ring in the main chain were synthesized from trans‐1,2‐cyclopropane diisocyanate (trans IC) and trans‐1,2‐cyclopropane diacylisocyanate (trans AIC). For example, the polymer obtained from methylene bis‐(4‐phenyl isocyanate) and trans‐1,2‐cyclopropane di(carbamoyl cyanide) prepared from trans IC showed an intrinsic viscosity of [η] = 0.45. Furthermore, the cyclic polymerization of cis‐1,2‐cyclopropane diisocyanate was studied; the highest intrinsic viscosity of the cyclic polymer was 0.11.
Beiträge zur lösungsviskosität. I. Über zusammenhänge zwischen kH (HUGGINS) und dem ausdehnungs‐koeffizienten αη und zwischen den verschieden definierten grenzviskositätszahlen [η]Θ, [η]T und [η]R untereinander
Authors: Berger Von Ralf
Published: April 2003

An Hand von Ergebnissen aus der Literatur und darauf aufbauenden Überlegungen wird eine Beziehung zwischen kH (HUGGINS) und αη (FLORY):

und eine zwischen verschieden definierten und verschieden bestimmbaren Grenzviskositätszahlen [η]Θ, [η]T und [η]R:

angegeben. Eine mögliche Anwendung dxieser letzten Beziehung zur Berechnung der realen Knäueldichte im Θ‐Zustand wird kurz diskutiert.
The role of various inorganic solid additives in radiation‐induced solid state polymerization of 3,3‐bis‐chloromethyloxetane
Authors: Kagiya Tsutomu , Izu Masatsugu , Fukui Kenichi
Published: April 2003

The effects of solid additives on the radiation‐induced polymerization of 3,3‐bis‐(chloromethyl) oxetane were studied. Some of the additives which acelerate the polymerization rate of the unpurified monomer, showed no effect with the purified monomer. The results obtained with the pure monomer, showed, that (1) the number of polymer chains under the same conditions was independent of the kind of solid additive, and was constant; (2) the rate of polymerization and the intrinsic viscosity of the polymer increased with irradiation time. From these results, it was concluded that the role of the additive was to depress a termination reaction by trapping the poison for polymerization.
Some remarks on the origin of weak chemiluminescence during polymer oxidation
Authors: Reich Leo , Stivala S. S.
Published: April 2003

Various kinetic expressions for the autoxidation of relatively simple hydrocarbons, based on chemiluminescence studies, were obtained by Russian workers. They assumed that the emitted light intensity, I, was a function of RO2•2 in order to explain their experimental data. This paper purports to show that much of their kinetic data can also be explained by assuming that I is a function of [RO2H].
Reaction modes and polymerization of crotonic esters with lithium aluminum hydride
Authors: Tsuruta T. , Makimoto T. , Miyazako T.
Published: April 2003

The reaction products of lithium aluminum hydride with crotonic esters under polymerization conditions were analyzed by gas chromatography. The ratios of carbon‐carbon double bond‐ to carbonyl‐addition of the hydride ion toward methyl, iso‐propyl, iso‐butyl and sec‐butyl crotonates are determined as 3:1, 20:1, 9:1, and 40:1, respectively. The intermediate double bond addition product was confirmed to be a precursor of the polymerization. The precursors undergo successive carbonyl‐addition onto monomer, terminating the propagation rapidly in the reactions with methyl and isobutyl esters; in case of iso‐propyl and sec‐butyl esters double bond additions yielded high polymers. The reaction product of methyl crotonate and lithium aluminum hydride showed good catalytic activity for polymerization of crotonates.
An approximate graphical estimation of activation energy from thermogravimetric traces
Authors: Reich Leo
Published: April 2003

An approximate graphical method is presented for the estimation of activation energy from thermogravimetric traces. The method is applied to octamethylcyclotetrasiloxane and to poly (tetrafluoro ethylene). Good agreement was obtained between calculated and reported values. Advantages and disadvantages of the method are given.
Catalyst behavior of aluminum alkyl systems in the polymerization of cyclic ethers
Authors: Saegusa Takeo , Ueshima Takashi , Tomita Shimpet
Published: April 2003

The polymerization of cyclic ethers, especially of epichlorohydrin, by AlEt3 and AlEt3/H2O system was studied. From the effects of solvent (CH2Cl2) and of a small amount of pyridine upon the copolymerization of epichlorohydrin with tetrahydrofuran, it has been assumed that there are at least two active species in these polymerizations: one is responsible for cationic polymerization and the other is for coordinate anionic polymerization. This assumption has been supported by the stoichiometric reactions of these catalysts with epichlorohydrin and also by the behavior of the alkoxide modified systems of AlEt3 and AlEt3/H2O.
Vinyl polymerization. 170. Grafting of some acrylates and methacrylates onto cellulose and silk in absence of radical initiators
Authors: Imoto Minoru , Takemoto Kiichi , Azuma Hei‐ichi , Kita Nobuyuki , Kondo Mitsuru
Published: April 2003

The polymerization and copolymerization of various acrylates and methacrylates in presence of cellulose or silk and water were studied without radical initiators. The polymerization of methacrylates proceeded more easily than that of acrylates, and in general the grafting was much higher onto silk than cellulose. It was also found that methyl methacrylate could be grafted onto OH‐group containing synthetic copolymers. Both optical and electron microscopic observations were made on the methyl methacrylate‐grafted silks.
Base‐catalyzed polymerization of sorbamide and β‐vinylacrylamide
Authors: Tsunetsugu T. , Matsuo T. , Furukawa J.
Published: April 2003

Sorbamide and β‐vinylacrylamide were polymerized using tert‐BuONa and n‐BuLi as catalysts. The resulting polymers were analysed by infrared spectroscopy and hydrolyzed to subject to paper chromatography. The hydrolysis products were primarily δ‐amino acids. Thus it was concluded that the polymerization proceeded mainly by the hydrogen transfer mechanism, leading to poly‐δ‐amides.

Poly‐β‐vinylacrylamides obtained by basic catalysts were insoluble, whereas polysorbamides were soluble at first but became insoluble on standing under air. Both these polyamides were amorphous.
Synthèse de nouvelles N‐glycidylamides cycliques. 14ième communication sur la chimie des résines époxydes1
Authors: Porret Par D.
Published: April 2003

La synthèse de nouvelles N‐glycidylamides cycliques est décrite et le mécanisme de la réaction est discuté. Certaines des nouvelles combinaisons sont bien solubles dans l'eau et permetient ainsi de nouvelles applications dans le domaine des résines époxydes. Celles qui sont peu solubles, durcies avec des anhydrides d'acides ou des amines, donnent des résines présentant de bonnes propriétés mécaniques et électriques.
The thermal degradation of poly(methyl acrylate). Part II. The mechanism of chain breaking
Authors: Cameron G. G. , Kane D. R.
Published: April 2003

The rate curves for the conversion of poly(methyl acrylate) to volatiles at 286–310°C show maxima in the region 10–20% conversion, consistent with random degradation with transfer. The molecular weight changes in the early stages of the reaction also suggest random breakdown. A reaction mechanism involving initiation by random homolytic back‐bone bond scission followed by a chain of free radical transfer reactions, inter‐ and intramolecular, is proposed. Chain‐end initiation appears to be unlikely. The free radical inhibitor 1.4‐diaminoanthraquinone was found to retard both volatile formation and random chain scission thus supporting the proposed mechanism. The energies of activation for volatile formation and random chain scission are 35 and 33 kcal/mole respectively.
Cross‐Linking efficiency of styrene‐butadiene rubber with dicumyl peroxide and evaluation of interaction parameter
Authors: Bhatnagar S. K. , Banerjee S.
Published: April 2003

The cross‐linking efficiency of dicumyl peroxide with styrene‐butadiene rubber (SBR‐1507) has been measured by the swelling method. The values are found to be 2.5 and 5.0 for unpurified and purified SBR, respectively. The lower value in the former case has been ascribed to the destruction of peroxy radicals by the antioxidants present in the rubber. The physical cross‐links due to chain entanglement for purified SBR are found to be 0.14 . 10−4 mole/g of rubber (0–07.10−4 cross‐links due to chain entanglement/g of rubber). The solubility parameter for purified SBR as determined from both swelling and viscosity measurements is found to be 8.45 (kcal/ml)1/2 or cohesive energy density as 71.403 kcal/ml. Using this value of the solubility parameter, the solvent‐polymer interaction parameter is calculated and is further verified by HUMMEL'S method. The average value is found to be 0.37.
Polycondensation‐addition. VI. Optically active polyurethan‐ureas
Authors: Lwakura Yoshio , Hayashi Katsumi , Inagaki Koichi
Published: April 2003

High molecular weight of optically active polyurethan‐ureas were prepared from optically active 2‐alkyl‐2‐isocyanatoethyl chloroformates and optically active diamines by interfacial polycondensation‐addition.

No dramatic differences in solid properties such as polymer melt temperature and crystallinity were observed between the optically active polyurethan‐ureas and the corresponding racemic polymers. The optical rotatory dispersions of the polymers in various solvents simply obeyed the one‐term DRUDE equation.
Polymerization of methyl isopropenyl ketone and coloration of the polymers
Authors: Matsuzaki Kei , Lay Ting Che
Published: April 2003

Isopropenyl methyl ketone was polymerized with γ‐ray radiation and with phenylmagnesium iodide in toluene. The polymers obtained with phenylmagnesium iodide as catalyst were separated into methyl ethyl ketone‐soluble and ‐insoluble parts. The soluble parts were amorphoas, while the insoluble parts were crystalline.

Treatment of the polymers by heat, alkali and chlorinated solvents induced aldol condensation. It was confirmed by infrared and ultraviolet spectrometry that the crystalline polymer underwent aldol condensation between adjacent units more easily than the amorphous polymer at temperatures lower than 180°C, forming monocyclic structures predominantly, whereas the amorphous polymer resisted in the earlier stage of heating but was more rapidly degraded between 180‐260°C than the crystalline polymer. The length of the conjugated double bond sequences produced in the amorphous polymer showed random distribution.
Copolymerization of cyclic ethers with vinyl compounds. II. Effects of copolymerization conditions on cationic copolymerization of epichlorohydrin with styrene
Authors: Mitoh Motonori , Minoura Yuji
Published: April 2003

Cationic copolymerization of epichlorohydrin with styrene was carried out under various conditions. The copolymer obtained was fractionated into two fractions: one was a methanol‐soluble liquid, and the other was a methanol‐insoluble solid polymer. The liquid polymer was found to be very rich in epichlorohydrin and the solid one was on the contrary very rich in styrene. The effects of catalysts, catalyst concentration, polymerization temperature and some other conditions on the copolymerization were investigated.
High resolution NMR studies on sequence distribution of vinylidene chloride copolymers
Authors: Ito Koichi , Iwase Seigo , Yamashita Yuya
Published: April 2003

Sequence distributions of several radical copolymers of vinylidene chloride were examined by NMR spectroscopy, including methyl methacrylate, benzyl methacrylate, methaeryloyl chloride, methyl acrylate, α‐methylstyrene, styrene, and vinyl acetate as comonomers. Except for the α‐methylstyrene and styrene systems, some of the diad, triad, and tetrad sequences were observed in the CH2 and αCH3 resonances and are discussed in the light of the usual copolymerization theory.
Polymerization of vinyl acetate under high pressure
Authors: Nakamoto Hideo , Ogo Yoshiaki , Imoto Tatsuya
Published: April 2003

High pressure radical polymerization of vinylacetate with and without solvents has been investigated in the range of 1–2000 kg/cm2.

The pressure has the ability to interrupt an occurrence of branching in bulk polymerization and the overall chain length of polyvinylacetate increases with pressure.

In solution polymerization, the magnitude of the activation volume of chain transfer to solvent is in following order: toluene > chlorobenzene > bromobenzene. In both cases, the overall rates of polymerizations and the molecular weights of polymers obtained increased with increasing pressure.

The overall activation volumes of vinylacetate polymerization are −17.4 ml/mole without solvent and −12.0 ml/mole in benzene.
Initiation of polymerization by sulphur dioxide and pyridine in the presence of organic halides
Authors: Bamford C. H. , Reynolds R. J. W. , Seddon J. D.
Published: April 2003

The initiation of the polymerizations of methyl methacrylate and styrene by sulphur dioxide + pyridine in the presence of organic halides has been studied. The kinetics are consistent with free‐radical reactions and indicate the occurrence of a rate‐determining step not involving the halide, forming an intermediate which yields radicals on reaction with the halide.

When polyvinyl trichloracetate (PVTCA) is the halide gelation occurs, showing that the primary radicals are attached to the PVTCA chain, and suggesting that radical formation involves removal of a halogen atom from the halide molecule.

This initiating system shows resemblances to those composed of a derivative of a zerovalent metal in association with an organic halide.
Catalytic activity of some chelate polymers derived from cupric ion and polymeric ligands having hydroxamic acid groups
Authors: Nozawa Tsunenori , Nose Yoshinori , Hatano Masahiro , Kambara Shu
Published: April 2003

The following chelate‐polymers were synthesized and their catalytic activity was investigated:

These chelate‐polymers were found to catalyse the decomposition of hydrogen peroxide. For purposes of comparison, the copper‐chelate of methyl hydroxamic acid (IV) also was synthesized; it showed no catalytic effect. The chelates (I) and (II), on the other hand, were found to have large catalytic activity for the decomposition reaction of hydrogen peroxide in aqueous solution, while their polymeric ligands alone exhibited no catalytic activity for this reaction, or, at least, less activity than the chelates themselves. In the case of the chelate (II), it was found that the catalytic activity depends on the molecular weight of the polymeric ligand.

On the basis of structural analyses by means of visible and infra‐red spectroscopy, the catalytic activity of these chelate polymers is assumed to depend on the bond strength between the ligand and the copper ion.
Pfropfcopolymerisationen mit makromolekularen polyradikalanionen und polyanionen
Authors: Braun Von Dietrich , Neumann Werner , Arcache Gilbert
Published: April 2003

Aus Copolymeren aus p‐Vinylbenzophenon, aus p‐Vinylbenzophenonanil und aus p‐Vinyl‐p′‐dimethylaminoazobenzol und Styrol entstehen mit Natrium in Tetrahydrofuran Lösungen der entsprechenden Polyradikalanionen und Polydianionen. Die makromolekularen Radikalanionen der beiden erstgenannten Copolymeren starten die Pfropfcopolymerisation von Acrylnitril und Methylmethacrylat, die entsprechenden Polydianionen darüber hinaus auch die Pfropfcopolymerisation von Styrol; mit Styrol entstehen dabei „lebende”︁ Seitenzweige. Vom Mononatriumaddukt des Copolymeren aus p‐Vinyl‐p′‐dimethylaminoazobenzol und Styrol wird nur Acrylnitril polymerisiert; die entsprechende Dinatriumverbindung bringt neben Acrylnitril noch Methylmethacrylat zur Pfropfcopolymerisation, aber nicht Styrol. Durch Lösungsversuche läßt sich zeigen, daß in den Pfropfprodukten mit Acrylnitril und Methylmethacrylat praktisch keine ungepfropften Rückgratpolymeren und keien Homopolymeren enthalten sind.
Polymerization of propylene to syndiotactic polymer. III. Behaviour of the catalyst system VCl4‐Al(C2H5)2Cl in the presence of lewis bases
Authors: Zambelli A. , Pasquon I. , Signorini R. , Natta G.
Published: April 2003

Polymerizations of propylene to syndiotactic polymer have been carried out in the presence of the catalyst system VCl4‐Al(C2H5)2Cl‐anisole. The data obtained have been related to those previously reported concerning the catalyst system, VCl4‐Al(C2H5)2Cl. It was thus possible to propose a mechanism of formation of the catalytic complexes and to put forward or confirm some hypotheses on their constitution.

A polymerization mechanism is also proposed that can justify both the type of stereoregularity of the polymer and the variation of steric regularity on varying the polymerization conditions.
Zur anionischen copolymerisation von α‐methylstyrol und styrol
Authors: Tölle Von J. , Wittmer P. , Gerrens H.
Published: April 2003

Im System α‐Methylstyrol (M1)/Styrol (M2) wurden die Copolymerisationsparameter für die anionische Copolymerisation bestimmt. Dazu wurde in Tetrahydrofuran als Lösungsmittel mit variiertem Monomerengehalt copolymerisiert. Die Reaktion kommt nach völligem Verbrauch des Styrols zum Stillstand, da α‐Methylstyrol unter den Versuchsbedingungen nicht homopolymerisiert. Aus dem Restgehalt an Monomeren kann man mit der integrierten Copolymerisationsgleichung die Parameter ermitteln. Gefunden wurden r1 = 0,015, r2 = 17 (25°C); r1 = 0,024, r2 = 28 (0°C); r1 = 0,029, r2 = 43 (−20°C).

Auf Grund der sehr unterschiedlichen r‐Werte verschiebt sich das Monomerenverhältnis während der Copolymerisation erheblich. Alle Makromoleküle wachsen im gesamten Umsatzbereich („living”︁‐Polymerisation) und sind untereinander gleichartig aufgebaut, zeigen aber entlang der Kette eine starke Änderung der Zusammensetzung. Wir bezeichnen dies als „chemische Uneinheitlichkeit 2. Art”︁.
Synthesis of α.α′‐dibromomethyl sulfid and some reactions
Authors: Komoto Hiroshi , Kobayashi Hidehiko
Published: April 2003

α.α′‐Dibromomethyl sulfide was obtained by reacting sym‐trithiane with bromine. Bromomethyl sulfenyl bromide was postulated as an intermediate in this reaction. The latter substance also condenses with ethylene to produce α.α′‐dibromomethyl ethyl sulfide. α.ω Dibromopolythimethylene was obtained by treating sym‐trithiane in bulk at 180°C with α.α′‐dibromomethyl sulfide. Polythiomethylene was obtained by treating α.α′‐dibromomethyl sulfide with water.
Vinyl polymerization. 194. Polymerization of methyl methacrylate in the presence of partially hydrolyzed polyvinyl acetate and water
Authors: Imoto Minoru , Takemoto Kiichi , Okuro Akyo , Izubayashi Masuji
Published: April 2003

The polymerization of methyl methacrylate was carried out without radical initiators,in the presence of partially hydrolyzed polyvinyl acetates and water. It was found that high molecular polyvinyl acetate and polyvinyl alcohol could not initiate the polymerization of inethyl methacrylate in the presence of water, while partially hydrolyzed polyvinyl acetates and formalized polyvinyl alcohol could initiate the polymerization. The results were discussed in connection with those of our series of studies.
Formaldehyde resins. 93. Reaction rate of polynuclear p‐cresol‐formaldehyde‐condensate with formaldehyde in acidic media
Authors: Imoto Minoru , Ijichi Ichiro , Tanaka Chiiaki , Kinoshita Masayoshi
Published: April 2003

The linear poly nuclear p‐cresol‐formaldehyde condensates up to octabodyll were syntHesized, and the rates of their reaction with formaldehyde in ca. 80% dioxane in the presence of perchloric acid were measured. The reaction rates of the one to four nuclear condensates (H1H ∼ H4H) were approximately double of those of higher nuclear condensates (H5H ∼ H8H). The abrupt decrease of the rate of tetrabody(H4H) to the pentabody (H5H) was explained by two considerations: The first is the rolling up form of the higher molecular condensate where the one end (i.e. the reactive site) is hidden by the molecule itself and the second is the formation of hydrogen bonds between all the hydroxyl groups to decrease the reactivity of the aromatic substitution with a methylol cation.
Über den einfluß von schwermetallspuren auf die kinetik der mit dem redoxsystem peroxydisulfat‐thiosulfat initiierten polymerisation von acrylnitril in wäßriger phase
Authors: Prölss Von H. , Patat F.
Published: April 2003

Bei strengem Ausschluß von Schwermetallspuren durch Anwendung starker Komplexbildner verläuft die Polymerisation von Acrylnitril (M) mit dem Redoxinitiator Peroxydisulfat (P)‐Thiosulfat (T) nach dem Zeitgesetz:

Bei hohen Thiosulfatkonzentrationen (> 2·10−2 mol/l) ist die Polymerisationsgeschwindigkeit jedoch unabhängig von dessen Konzentration. Das Viskositätsmittel des Polymerisationsgrades steigt linear mit zunehmender Konzentration des Monomeren und zeigt in weitem Bereich keine Abhängigkeit von der Konzentration des Katalysatorsystems. Oberhalb einer Thiosulfatkonzentration von etwa 2·10−2 mol/l verläuft der Polymerisationsgrad etwa umgekehrt proportional zur Konzentration des Thiosulfates. Die Befunde werden durch ein Reaktionsschema mit einer Abbruchsreaktion erster Ordnung gedeutet, das sich in Übereinstimmung mit der Kinetik der unkatalysierten Redoxreaktion befindet.

In Anwesenheit von Spuren von Übergangsmetallen, untersucht am Beispiel des Kupfers, ergibt sich das veränderte Zeitgesetz:

Der Polymerisationsgrad (P̄) folgt der Beziehung:

Diese experimentellen Ergebnisse werden durch ein Polymerisationsschema interpretiert, das den üblichen Abbruch zweiter Ordnung durch gegenseitige Desaktivierung zweier aktiver Polymerradikale postuliert.

Die kinetischen Daten im untersuchten Konzentrationsbereich lassen sich durch einen überwiegenden Start der Polymerisation durch Reaktion von SO•‐Radikal‐Ionen mit dem Monomeren deuten.
Anionic polymerization of β‐substituted acrylic esters
Authors: Tsuruta Teiji , Makimoto Tsutomu , Tanabe Kiyoshi
Published: April 2003

Anionic polymerizations of methyl and other n‐alkyl cinnamtes with organometallic catalysts were studied. Calcium‐zinc‐tetraethyl showed the greatest catalytic activity for the polymerization of the above monomers. In copolymerization of cis and trans isomers of methyl crotonate and isopropyl crotonate the trans isomers were found to have greater reactivities. Cis‐Isomers, on the other hand, seemed to form more stereoregular polymers. Properties of polyalkyl crotonates and polyalkyl cinnamates were studied with the aid of X‐ray, IR and NMR spectra.
Thermal polymerization and electronic spectra of vinylpyridine‐zinc acetat system
Authors: Tazuke Shigeo , Okada Takeshi , Okamura Seizo
Published: April 2003

Thermal rate of polymerization of 4‐vinylpyridine (4‐VP) was found to increase greatly in the presence of zinc acetate. The occurrence of radical polymerization was confirmed by studying the effects of additives (2.2‐diphenyl‐1‐picrylhydrazyI (DPPH), air and water). Using zinc acetate as catalyst in THF, the order of thermal rate was 4‐VP > MVP > 2‐VP (no polymerization).

It was concluded that the enhancement of the rate of thermal polymerization was not only due to the increase of propagation rate but also due to the thermal production of radicals by the interaction between monomer and metal salts.

The influence of zinc salts on the electronic state of vinylpyridines was studied by electronic spectroscopy. The π→π* transition band of 4‐VP was observed to shift towards lower energy by complexing the monomer. The amounts of shift of 2‐metlyl‐5‐vinylpyridine (MVP) and 2‐vinylpyridine (2VP) were much smaller than those of the 4‐VP‐complexes. These spectral data were discussed on the basis of the electornic interction of metal ion with ligand as well as the steric effect in complex formation, and were correlated to the thermal polymerizabilities of complexed vinylpyridines.
Influence de la nature du solvant et de la température sur les dimensions non perturbées des copolymères statistiques PS–PMM
Authors: Dondos Par Anastasios , Benoît Henri
Published: April 2003

The STOCKMAYER‐FIXMAN method has been applied to determine the unperturbed dimensions of a polymer chain from viscosity measurements on several fractions in a good solvent. Homopolymers yield values of the unperturbed dimensions which are independent of the nature of solvent and which hardly depend upon temperature.

Using the same method for [η] measurements in different solvents, the values obtained for random copolymers PS–PMMA are quite different from the “ideal” values calculated on the basis of additivity rules from the unperturbed dimensions of corresponding homopolymers. The discrepancy was shown to depend on the χAB parameter, which also governs the critical concentration for phase separation for a solution of the corresponding homo polymers.

Since χAB is solvent and temperature dependent, the observed variation in the unperturbed dimensions from one solvent to another can be qualitatively explained. Linear relation was found between χAB and KΘ leading to KΘ “ideal” for χAB = 0.

Moreover, the temperature dependence of unperturbed dimensions for a random copolymer, in a given solvent, is much stronger than for an homopolymer. As temperature increases χAB decreases and the unperturbed dimensions approach the “ideal” values.

These results show the influence of heterocontact interactions on chain conformation. They clearly demonstrate their importance at theta conditions by influencing the dimensions of the chain.
Amine‐induced copolyaddition of p‐chlorophenyl glycidyl ether with cis‐hexahydrophthalic anhydride
Authors: Tanaka Yoshio , Haung C. M.
Published: April 2003

The copolyaddition reaction ofp‐chlorophenyl glycidyl ether with cis‐hexahydrophthalic anhydride was investigated in the presence of tri‐n‐butylamine in xylene by varying monomer compositions. The yield and the molecular weight of the polymeric product increased with time and had maximum values at the equimolar mixture of monomers. The amine is found to suppress largely the undesirable side reactions of epoxide and anhydride homopolymerizations. With excess epoxide, the copolymers are better than 90% hydroxylterminated, and with a large excess of anhydride, carboxyl termination predominates. Agreement between the partial epoxide contents without chain end units in polymeric products by the chlorine content and by the saponification number is very good to about 50 mole‐%, which implies that both epoxide and anhydride become strictly bifunctional toward each other. The suitability of the mechanism proposed previously for this reaction was discussed in the light of the observed phenomena.
Hochdisperse, vernetzte kondensationspolymere aus melamin und formaldehyd
Authors: Renner Von Alfred
Published: April 2003

Die Fällung order Gelierung von Melamin‐Formaldehyd‐Kondensationsprodukten in Gegenwart von Schutzkolloiden (z. B. Na‐Carboxymethylcellulose) führt zu vernetzten Polymeren mit spezifischen Oberflächen bis zu 250 m2/g. Die Abhängigkeit der spezifischen Oberfläche von der Art und von der Menge des Schutzkolloids, vom pH‐Wert, vom Molverhältnis und von der Konzentration der polymerbildenden Komponenten wird mitgeteilt.

Elekronenmikroskopische Abbildungen zeigen kugelförmige Teilchen. Polymere mit spez. Oberflächen unter 100 m2/g bestehen aus Partikeln zweier verschiedener Größenordnungen (1−5μ resp. ≤ 500 Å). Oberhalb 100 m2/g sind mur kolloide Teilchen vorhanden.

Der chemische Einbau des Schutzkolloids in die Polymerpartikel wird nachgewiesen; eine Hypothese ihrer bildung wird gegeben. Obere Grenzwerte der mittleren Molekulargewichte der Polymeren wurden berechnet (M = 6·106 bis 4·107.

Hochdisperse vernetzte Melamin‐Formaldehyd‐Polymere eignen sich wegen ihrer gleichmäßigen Partikelstruktur und wegen ihrer oberflächenreaktivität als verstärkende Füllstoffe für Naturkautschuk und fü synthetische Elastomere.
Über die photosensibilisierte autoxydation von polyvinylalkohol
Authors: Dulog Von Lother , Kern Rudolf , Kern Werner
Published: April 2003

Polyvinylalkohol wurde in wäßriger Lösung bei 30°C unter Belichtung mit einer Quecksilberhochdrucklampe einer mit benzophenn‐3.3′‐disulfonsaurem Natrium photosensibilisierten Autoxydation unterworfen. Als Reaktionsprodukte wurden Wasserstoffperoxid, Säuren und Kohlendioxid ermittelt. Unter den gewählten Reaktionsbedingungen werden die Makromoleküle statistisch abgebaut. Viskositätsmessungen und analytische Bestimmungen zeigen, daß pro Spaltung der polymerkette nur eine Carboxylendgruppe entsteht. Ein Reaktionsmechanismus wird diskutiert.
Zur polymerisation von alkenyloxysilanen mit organischen vinylverbindungen
Authors: Runge Von Franz , Abel Walter
Published: April 2003

Es wird über die Darstellung von Trialkylvinyloxysilanen und Trialkylallyloxysilanen und ihre hydrolytische Beständigkeit berichtet.

Trialkoxyvinyloxysilan und Trialkoxyallyloxysilan wurden mit einigen Monomeren copolymerisiert. Dann wurden die Alkoxy‐Gruppen der Hochpolymeren verseift und aus den linearen Makromolekülen durch eine sekundäre, zwischenmolkular kondensation chemisch und thermisch hochresistente, vernetzte Polymere erhalten.
Über die entropie‐ und energieelastizität von vernetzten hochpolymeren
Authors: Schäfer Von Ernst Erich , Rehage Güunther
Published: April 2003

Die elastischen Eigenschaften von Polymethylmethacrylat (PMMA), in Substanz oder in Lösung vernetzt, sowie von Naturkautschuk und Polybutadien, das über die Endgruppen verneut war, wurden mit Hilfe eines Torsionspendels untersucht. Die Messungen wurden an gequollenen und ungequollenen Proben in Abhängigkeit von der Temperatur durch‐geführt.

In einem größeren Temperaturbereich wurde ein linearer Anstieg des Speichermoduls G' mit der Temperatur beobachtet, wenn die Proben sorgfältig extrahiert waren. Der Speichermodul wurde in einen entropieelastischen Anteil G'S und einen energieelastischen Anteil G'U aufgespalten. Aus dem entropieelastischen Anteil wurde die effektive Vernetzungsdichte berechnet. Sie erwies sich im Rahmen der Meßgenauigkeit als unabhängig vom Quellungsgrad, wie es die statistische Theorie der Gummielastizität fordert.

Bei den PMMA‐ und Naturkautschukproben nahm der relative energieelastische Anteil G'U/G' mit steigendem Quellungsgrad stark zu. Dieses Verhalten wurde auf die kurzen Netzbögen zurückgeführt, die bei breiter Verteilung der Netzbogenlängen immer vorhnden sind. Diese Deutung wird gestützt durch die Ergebnisse der Messungen an den über Endgruppen vernetzten Polybutadienproben, die eine schmale Verteilung der Netzbogenlängen besitzen. Für diese Polybutadiene ist der energieelastische Antell G'U/G' des Speichermoduls unabhängig vom Quellungsgrad praktisch gleich Null; sie verhalten sich zummindest bei kleinen Deformationen rein entropieelastisch.
Über die stereospezifische polyreaktion von styrol mit löslichen ZIEGLER‐NATTA‐katalysatoren. II.
Authors: Reichert Von K. H. , Berthold J.
Published: April 2003

Es wurde die Polyreaktion von normalem, α‐ und β.β′‐deuteriertem Styrol mit dem löslichen Mischkatalysator (C5H5)2TiCl2/Al(C2H5)2Cl in Benzol untersucht und auch die Taktizität der gebildeten Polymeren ermittelt.

Dabei wurde festgestellt, daß die Polymerisationsgeschwindigkeit von α‐deuteriertem Styrol größer als die des normalen und des β.β′‐deuterierten Monomeren ist. Die Geschwindigkeiten der beiden letzten sind gleich. Die Größe des Isotopeneffektes hängt vom Verhältnis der Katalysatorkomponenten und von der Monomerkonzentration ab. Als einfachste Ursache für den ermittelten lsotopeneffekt ergibt sich die bimolekulare Abbruchreaktion, die offensichtlich unter Spaltung einer β‐ständigen CH‐Bindung der wachsenden Kette erfolgt. Auch kann aus dem Befund, daß nur das α‐deuterierte Styrol eine Reaktionsbeschleunigung bewirkt, geschlossen werden, daß es sich bei dieser Polyreaktion ausschließlich um eine 1.2‐Addition der Monomereinheiten handelt. An Hand der IR‐Spektren des β.β′‐deuterierten Polystyrols wird wahrscheinlich gemacht, daß die vorliegenden Polymeren große Anteile isotaktischer Strukturen besitzen. Es wird ferner über die Aktivitätsverhältnisse eines „makromolekularen”︁ ZIEGLER‐NATTA‐Katalysators berichtet.
Copylymères séquences polyoxyéthylène‐polyacrylonitrile. Essais de préparation par voie anionique
Authors: Galin Par J. C.
Published: April 2003

The anionic Polymerization of acrylonitrile has been intiated by sodium of lithium alcoholate of Polyxyethylene glycol. Experiments have been carried out at low temperature in dimethylformamide solution. Slightly coloured block copolymers have thus been obtained. The following conclusions have been drawn from the experimental results:

the acrylonitrile consumption is quantitative,

the efficiency of the macroinitiator is low,

polyoxyethylene and polyacrylonitrile homopolymers are likely to be present in the crude reaction product,

the anionic polymerization mechanism implies for the polyacrylonitrile blocks a highly branched structure.
Die förderung der kristallisation von polymeren durch hochmolekulare keimbildner
Authors: Hoffmann Von M.
Published: April 2003

Einige schlecht kristallisierende Polymere lassen sich durch inniges Zumischen von wenigen Prozent eines chemisch nahezu gleichen, aber gut kristallisierenden Polymeren zu schnellerer und stärkerer Kristallisation anregen. So erhöhen beispielsweise 6 Gew.‐% eines sehr schnell kristallisierenden Polychloroprens bei 20°C die dilatometrisch gemessene Kristallisationsgeschwindikeit der Iangsam kristallisierenden Polychloroprene Baypren 210 oder Neoprene W auf das 20‐fache und den maximal erreichbaren Kristallisationsgrad auf das 4,5‐fache. Untersuchungen bei verschiedenen Temperaturen zeigen ferner, daß der Schmelzpunkt der Mischung 13°C höher liegt als der des langsam kristallisierenden Polychloroprens und daß die Temperaturabhängigkeit der Kristallisationsgeschwindigkeit geringer ist als die von ungemischten Polychloroprenen. Die Kristallisationsgeschwindigkeit bei 22°C ist dem Quadrat der Konzentration des zugesetzten „Keimbildners”︁ proportional, während die Erhöhung des Kristallisationsgrades der Wurzel aus dieser Konzentration proportional ist. Aus diesen Gesetzmäßigkeiten und der Schmelzpunkterhöhung folgt, daß Mischkristalle gebildet werden. Ähnliche Verstärkungen der Kristallisation werden bei Polyvinylchlorid und ähnlichen Polymeren sowie bei cis‐Polyisopren und cis‐Polybutadien gefunden. Diese Befunde stehen jedoch im Gegensatz zu denen, die man bei Gemischen aus Polyäthylen mit Üthylen‐Copolymeren und bei einigen anderen Polymeren und Copolymeren beobachtet. Dort findet diese Kristallisationsförderung nicht statt, weil anscheinend eine Kettenfaltung die Mischkristallisation hindert.
Cationic copolymerization of cyclic ethers with vinyl compounds. IV. Cationic copolymerization of propylene oxide with styrene
Authors: Minoura Yuji , Mitoh Motontori
Published: April 2003

When a mixture of propylene oxide and styrene in methylene dichloride was reacted with boron trifluoride etherate as catalyst, a copolymer and the homopolymer of propylene oxide were formed. The poly(propylene oxide) was formed almost quantitatively in the initial stage of the reaction. The amount of homopolymer then gradually decreased as the formation of the copolymer progressed. The copolymer was also formed by the polymerization of styrene in the presence of poly(propylene oxide). The copolymerization is thought to proceed largely by a chain‐transfer reaction.
Vinyl polymerization initiated with dimethylaniline N‐oxide and metal salts
Authors: Sato Tsuneyuki , Otsu Takayuki
Published: April 2003

A study of the polymerization of methyl methacrylate with catalyst systems of dimethylaniline N‐oxide (DMAO) and some metal salts especially Co(II)nitrate has been made. From the results of kinetic studies and of the copolymerization with styrene, it was found that the polymerization initiated with the DMAO/Co(II)nitrate system proceeds via radical mechanism. The change in visible spectra of DMAO/Co(II)nitrate system and kinetic results showed that one mole of Co(II)nitrate and six moles of DMAO form a coordinate complex in the polymerization system and this complex plays an important role for the initiation. The polymer obtained using this system was found to contain one end group similar to dimethylaniline from its UV spectrum. From these results and from the product analysis of the reaction of DMAO with Co(II)nitrate, the initiation mechanism with these initiator systems is discussed.
Cationic polymerization of α·β‐disubstituted olefins. Part XI. Polymerization of 2‐chloroethyl propenyl ether catalyzed by BF3·O(C2H5)2
Authors: Higashimura Toshinobu , Ohsumi Yukihiko , Okamura Seizo , Chûjô Riichiro , Kuroda Takamune
Published: April 2003

2‐Chloroethyl propenyl ether (CEPE) was synthesized, and its cationic polymerizability by BF3·O(C2H5)2 and the steric structure of the resulting polymer were studied. In the polymerization in toluene at −78°C, the rate of consumption of monomers decreased in the following order: cis‐CEPE > 2‐chloroethyl vinyl ether > trans‐CEPE.

The steric structure of the β‐methyl group of the resulting polymer was determined quantitatively on the basis of the NMR spectrum of the β‐methyl protons decoupled from β‐methine protons. In the polymerization of CEPE in toluene at −78°C, the polymer obtained from trans‐CEPE was rich in threo‐meso structure whilst cis‐CEPE gave a polymer containing almost the same amount of threo‐meso and erythro‐meso structures. With methylene chloride as solvent, the amount of threo‐meso structure increased and that of erythro‐meso structure decreased for the polymer obtained from cis‐CEPE. The steric structure of the polymer obtained from trans‐CEPE was independent of the nature of the solvent used. The effect of polymerization temperature on the steric structure of the polymers was also investigated.