bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive polymers. XX. The preparation of a carrier with aldehyde groups by oxidation of a macroporous glycidyl methacrylate‐ethylenedimethacrylate copolymer with periodic acid
Authors: Švec F. , Hrudková H. , Kálal J. 
Published: April 2003

AbstractThe oxidation of a macroporous glycidyl methacrylate‐ethylenedimethacrylate copolymer and of a polymer formed by its hydrolysis was investigated at temperatures ranging from 5 to 80°C with various concentrations of periodic acid. The reaction yields (formylmethyl)‐methacrylate units bearing free aldehyde groups capable of further reactions. The results allowed to estimate the activation energy of the reaction (60 and 27.5 kJ mol‐1) and to discuss its mechanism. The oxidation of the epoxide group seems to proceed in two steps with vicinal glycol as the intermediate product.
Flash photolysis investigation on primary processes of the sensitized polymerization of vinylmonomers. III. Photoreactions of benzoin compounds and stationary polymerization experiments
Authors: Kuhlmann Ralf , Schnabel Wolfram 
Published: April 2003

AbstractBenzoin (B), benzoinacetate (BA), benzoinmethylether (BME) and benzoinisopropylether (BIPE) were irradiated at room temperature in benzene solution in the presence of styrene (St), methyl methacrylate (MMA), vinylacetate (VAc) or acrylonitrile (AN). Flash photolysis experiments at λ=347 nm yielded (a) rate constants kq (in 1 mol‐1s‐1) of the reaction between excited sensitizers and monomers: 8·109 (B/St), 5·108 (B/MMA), 5·109 (BA/St), 8·108 (BA/MMA); (b) rate constants KR.+M (in 1mol‐1 s‐1) of the reaction between sensitizer radicals and monomers: about 1.5·105 (BME/St, BME/VAc, BA/VAc, B/VAc), 9· 104 (BME/MMA), 2·104 (BME/AN). The reaction R·+M caused in certain cases (B/St, B/VAc, BME/St) the formation of an additional optical absorption after the flash.Stationary irradiations at λ>320 nm of monomer solutions (5mol/1) showed that BA is least effective. Rates of polymerization increased in the series BA<B<BIPE<BME. For the systems containing St or MMA it was found that ϕi=i+0.6αR (ϕi=quantum yield for the initiation of kinetic chains, αR =fraction of triplets converted to radicals). The fraction of radicals starting kinetic chains is ca. 0.3 in these cases.
Polymerization of lactams, 27. Effect of reaction conditions on the anionic polymerization of 2‐pyrrolidone (part 4)
Authors: Roda Jan , Hula Zdeněk , Kušková Marie , Králíček Jaroslav 
Published: April 2003

AbstractThe effect of initiator and activator concentration on the course of the activated anionic polymerization of 2‐pyrrolidone was investigated. Potassium tert‐butoxide and N‐benzoylpyrrolidone, respectively, were used as polymerization initiator and activator. The course of the polymerization process was discussed on the basis of the polymer yield, molecular weight, and the content of basic groups in the polymer. The conversion dependences were presented in the form of an empirical mathematical equation.
Redox polymers containing p‐phenylenediamine groups
Authors: Bleha M. , Plichta Z. , Votavová E. , Kálal J. 
Published: April 2003

AbstractOxidation‐reduction reactions and some applications of polymers containing p‐phenylenediamine skeleton in side branches were studied in aqueous solutions. The polymer was used also for preparation of immobilized enzymes by oxidative coupling reaction. The materials were prepared under biologically tolerable conditions and exhibited fairly high biological activity.
On factors determining the swelling ability of crosslinked polymers
Authors: Tsyurupa M. P. , Andreeva A. I. , Davankov V. A. 
Published: April 2003

AbstractMacronet isoporous styrene polymers were obtained by a cross‐linking process (using monochlorodimethyl ether as the cross‐linking agent) applied to both dissolved linear polystyrene and swollen styrene copolymers with 0.3–1.0% divinylbenzene at the same polymer‐solvent weight ratio for all the systems. The lower equilibrium swelling capacity of copolymer‐based three‐dimensional structures as compared to that of linear polystyrene cross‐linked to an equal extent is explained by the presence in the initial swollen styrenedivinylbenzene copolymers of internal strains inhibiting an increase in the volume of the final polymer network. Cross‐linking of the linear polystyrene by means of a partially chloromethylated polystyrene shows that irregularity in the distribution of cross‐linking bridges enhances the equilibrium swelling capacity of the final gels.
Etude des copolymères acryliques utilisés dans l'encollage de fils de polyester II. Caractéristiques physicochimiques des copolymères et des systèmes composites polyester‐colles
Authors: Lucas Jean‐Michel , Berticat Philippe , Chabert Bernard , Nemoz Guy , Bardy M. , Exbrayat P. E. , Schutz R. A. 
Published: April 2003

AbstractUn copolymère acrylonitrile‐acide acrylique et un copolymère acrylonitrile‐acide acrylique ‐ acrylate d'éthyle représentant respectivement un mauvais et un bon encollage sont retenus pour l'é de l'encollage des fils continus de polyesters.Une corrélation est établie entre les paramètres physicomécaniques de ces matériaux et l'efficacité de l'encollage. Des données relatives à la répartition des colles, aux énergies de collage et aux paramètres viscoélastiques sont discutées. Une importance particulière est accordée à l'influence du taux de colle déposée et de l'humidité atmosphérique.
Studies on syntheses and permeabilities of special polymer membranes. XI. Permeation characteristics of grafted poly(vinyl alcohol) membranes
Authors: Uragami Tadashi , Wakai Toshitsugu , Sugihara Mizuho 
Published: April 2003

AbstractThe permeation characteristics of membranes grafted with various vinyl monomers onto poly(vinyl alcohol) were investigated by changing the mixture in graft copolymerization, the heat treatment and feed temperature. It was found that changes in permeation characteristics relate to changes of physical structure, such as micro‐phase separation and compaction under pressure, and of chemical structure, such as fraction of hydrophilic and hydrophobic groups in the resulting membranes. By comparing the permeation charactersitics for several feed solutes of the grafted membranes (methylmethacrylate grafted onto poly(vinyl alcohol) and onto poly(ethylene glycol)), it was found that the interaction between feed solute molecules and membrane substrate is an important factor.
Studies on syntheses and permeabilities of special polymer membranes. XII. Permeation characteristics of alkali bridged poly(vinyl alcohol) membranes treated with m‐cresol
Authors: Uragami Tadashi , Sugihara Mizuho 
Published: April 2003

AbstractAlkali bridged poly(vinyl alcohol) membranes with permeation stability for aqueous solutions were prepared by treatment with m‐cresol. It was found that the permeation stability was dependent on structural changes of the resulting membranes based on an increase of the content of hydrogen bonds between hydroxyl groups of poly(vinyl alcohol) molecules and on crystallinity. The permeation characteristics with variations of membrane thickness, polymer solute in the feed, and operating pressure were discussed.
Evaluation of data in sieve analysis of polymer‐based sorbents by means of a new distribution function
Authors: Kubín M. , Horák D. , Švec F. 
Published: April 2003

AbstractA new function with four adjustable parameters is proposed as a model of complex particle size distribution curves of particulate materials. A method for determination of its parameters from experimental data obtained by sieve analysis is described and the flexibility of the new function is illustrated on examples of artificial and experimental distributions.
Über eine Verwendung von Puffersystemen für Schwermetallionen bei der Acrylnitril‐Vinylchlorid‐Copolymerisation
Authors: König Joachim , Süling Carlhans 
Published: April 2003

AbstractCopolymerisate aus Acrylnitril und Vinylchlorid werden in wäßriger Emulsion mit dem Redoxkatalysator Ammoniumperoxodisulfat/Natriumhydrogensulfit hergestellt. Wesentlich für die Reproduzierbarkeit des Polymerisationsansatzes ist eine Kontrolle der Konzentration von Schwermetallionen, die durch Reaktionskomponenten und durch korrodierende Anlagenteile eingeschleppt werden können. Störungen der Copolymerisation durch wechselnde Schwermetallionenkonzentrationen äußern sich in unterschedlichen Umsatzgeschwindigkeiten gleicher Ansätze. Man erhält dann Polymerisate mit wechselnden chemischen Zusammensetzungen und Molekulargewichten.Um unkontrollierbare Schwankungen der Reaktionsbedingungen zu vermeiden, werden mehrere Komplexbildner auf ihre Wirksamkeit als Komponenten von Puffersystemen für Schwermetallionen untersucht.Mit dem System Eisen(II)‐ammoniumsulfat/Citronensäure (Molverhältnis: 1:33,8) gelingt es, die Störanfälligkeit des Polymerisationsansatzes gegenüber Schwankungen der Eisenionenkonzentration herabzusetzen und die Copolymerisation reproduzierbarer, d. h. mit einer verringerten Standardabweichung der Analysendaten durchzuführen.
Homopolymerization of isopropyl vinyl ketone and influence of the microstructure on the photodegradation of the polymer obtained
Authors: Acosta José Luis , Garcia Mercedes , Sastre Roberto 
Published: April 2003

AbstractThe kinetic equation of the radical polymerization of isopropyl vinyl ketone at 60°C using benzene as solvent and AIBN as initiator was determined. The influence of the microstructure on the photodegradation rate of atactic and crystalline poly(isopropyl vinyl ketone) (PIVK) was also investigated. The photolysis of atactic and crystalline samples of PIVK was carried out in solution and in the solid state. By effect of radiation, crosslinking and chain‐scission, or only chain‐scission, was observed, this behaviour was depending on the aggregation state of the sample. It was proved that the chain mobility plays the main role in the photodegradation of PIVK.
Reactive polymers. XXI. Preparation and characterization of crosslinked polymers with functional aldehyde groups and their reactivity
Authors: Zacharieva E. I. , Bleha M. , Žůrková E. , Mikeš F. , Kálal J. 
Published: April 2003

AbstractCrosslinking polymerization leading to poly(styrene‐co‐divinylbenzene‐co‐methacrolein) and poly(divinylbenzene‐co‐methacrolein) was studied together with the reactivity of the functional aldehyde groups. The surface characteristics of prepared polymers and their reactivity depend on the composition of the inert phase used in the suspension polymerization.
Über die Einwirkung konzentrierter Erdalkalihydroxyde auf Harnstoff‐Formaldehyd‐Harze
Authors: Baumann Heinz 
Published: April 2003

AbstractTechnische Harnstoff‐Formaldehyd‐Harze werden in der Wärme durch Einwirkung von Erdalkalihydroxyden weitgehend entmethyloliert, wobei die höhermolekularen methylenverbrückten Oligomeren und bereits teilvernetzte Kondensate ausfallen. Die Abspaltung ist nicht quantitativ, da die Spaltlösung noch niedermolekulare lösliche methylolgruppenhaltige Oligomere enthält. Der freigesetzte Formaldehyd wird hauptsächlich durch Aldolisierung zu Hexosen irreversibel gebunden.
Urea‐formaldehyde resins. Part 2. The formation of N,N‐dimethylolurea and trimethylolurea in urea‐formaldehyde mixtures
Authors: Kumlin Kjell , Simonson Rune 
Published: April 2003

AbstractN,N‐Dimethylolurea and trimethylolurea have been isolated by means of preparative liquid chromatography and identified by 270 MHz 1H‐NMR analysis in DMSO‐d6. The formation of these compounds at different formaldehyde‐urea molar ratios was examined. At high ratios (F/U≥4), trimethylolurea was the dominant monourea methylol compound. Formation of tetramethylolurea was not observed. N,N‐Dimethylolurea was formed to a much lesser extent than N,N'‐dimethylolurea.
NMR study on furfurylalcohol‐formaldehyde equilibrium systems
Authors: Faix F. , Gyevi E. Boros , Baitz‐Gács E. , Tüdős F. 
Published: April 2003

AbstractEquilibrium reactions in the beginning of the process of furfurylalcohol‐formaldehyde resin‐production have been studied. Based on 1H‐and 13C‐NMR analysis the components of the system have been quantitatively determined. Equilibrium constant values of the simultaneous reactions have been calculated.
Einfluß von Lösungsmitteln auf den Partikeldurchmesser von Dispersionen anionischer Polyurethanionomerer
Authors: Lorenz Otto , Hick Hugo 
Published: April 2003

AbstractWäßrige Dispersionen anionischer Polyurethane wurden durch Umsetzung von Polyäthern, 1,6‐Hexamethylendiisocyanat, Trimellitsäureanhydrid und Triäthylamin erhalten. Die Dispergierung erfolgte sowohl durch Phasenumkehr als auch durch Fällung, indem die Lösung oder Schmelze des Ionomeren mit Wasser versetzt bzw. in Wasser eingerührt wurde.Der Acetongehalt beeinflußt den mittleren Partikeldurchmesser D̄T, der aus Trübungsmessungen erhalten wurde. Es existiert eine optimale Acetonkonzentration, bei der D̄T ein Minimum erreicht. Ein ähnlicher Effekt tritt auf, wenn Tetrahydrofuran, 2‐Butanon oder Acetonitril als Lösungsmittel an Stelle von Aceton verwendet wird.Bei der Fällungsdispergierung bilden nur hinreichend verdünnte acetonische Lösungen feinteilige Dispersionen, während aus konzentrierten Lösungen Dispersionen mit einer breiten Partikelgrößenverteilung resultieren.
Konduktometrische Bestimmung der Oberflächenladung bei Dispersionen kationischer Polyurethanionomerer
Authors: Lorenz Otto , Budde Vladimir 
Published: April 2003

AbstractBei Dispersionen kationischer Polurethane, die durch Umsetzung von NCO‐Präpolymeren mit N,N‐Dimethyl‐2,2‐dimethylol‐1‐butylamin und nachfolgende Neutralisation mit HCI nach dem Aceton‐Verfahren hergestellt wurden, konnte durch konduktometrische Titration mit AgNO3 bzw. NaOH in Gegenwart eines nichtionogenen Netzmittels der Anteil der in den Partikeln eingeschlossenen Ionenpaare bestimmt werden. Dieser Anteil betrung weniger als 5% der vorgegebenen Cl− ‐Ionen und war praktisch unabhängig vom mittleren Partikeldurchmesser. Außerdem wurde versucht, die Oberflächenladung nach partiellem Ionenaustausch mit einem Anionenaustauscher durch konduktometrische Titration der entstandenen Base mit HCl und Bestimmung des Restgehaltes der Cl− ‐Ionen mit AgNO3 zu ermitteln, jedoch ergab die Titration mit HCl einen systembedingten Fehler. Darüber hinaus konnte nachgewiesen werden, daß nichtneutralisierte tertiäre Aminogruppen ausschließlich im Inneren und nicht auf der Partikeloberfläche lokalisiert sind. Bei Herabsetzung des Acetongehaltes wurde, bedingt durch geringere Solvatation, zunehmend weniger als die äquivalente Menge der tertiären Aminogruppen neutralisiert.
Reactive polymers XXIII. Sorption properties of macroporous chelate‐forming resin from the copolymer glycidyl methacrylate‐ethylenedimethacrylate containing iminodiacetic groups
Authors: Kálalová Eliška , Beiglová Vladimíra , Kálal Jaroslav , Švec František 
Published: April 2003

AbstractThe sorption and desorption kinetics, capacity and stability were investigated in repeated applications using a series of metal ions and a chelate‐forming resin based on the copolymer of glycidyl methacrylate‐ethylenedimethacrylate with iminodiacetate groups. The order of selectivity at pH = 5.4 in an acetate buffer solution was found to be Cu(II) ≥ Fe(III) ≥ Co(III) ≥ Ag(I) ≃ Al(III) ≥ Ni(II) ≥ Mn(II) ≥ Zn(II) ≥ Pb(II) ≥ UO2(II). The distribution coefficients of these ions were determined as a function of pH. The properties of the investigated resin were compared with those of the commercial Lewatit TP 207.
Functional monomers and polymers, 52. Inclusion polymerization of 2,3‐dimethyl‐1,3‐butadiene: Competitive incorporation of additives with the monomer in deoxycholic acid canals
Authors: Miyata Mikiji , Shinmen Katsutoshi , Takemoto Kiichi 
Published: April 2003

AbstractInclusion polymerization of 2,3‐dimethyl‐1,3‐butadiene in deoxycholic acid canals was studied in the presence of several types of non‐polymerizable organic compounds including alkanes and polar molecules. These compounds were found to be incorporated competitively with 2,3‐dimethyl‐1,3‐butadiene monomer into deoxycholic acid canals, causing thereby much or less decrease in the rate of polymerization depending on the structure of additives. Deoxycholic acid canals were found to incorporate more favorably branched or cyclic alkanes than linear ones. From the results obtained, the behaviour of competitive incorporation was discussed in relation to the polymerizability of the monomer within the canals.
Significance of the intrinsic viscosity ratio of unsubstituted and nitrated cellulose in different solvents
Authors: Marx‐Figini Marianne 
Published: April 2003

AbstractIt has been studied the intrinsic viscosity ratios of cellulose solutions in different solvents and of the corresponding nitrates dissolved in aceton using cellulose samples from different origins and with different degrees of polymerization. The results demonstrate that with FeTNa and CdEn as solvents, molecular dispersed solutions are only produced with cellulose having a DP≤3000. FeTNa is limited to cotton cellulose only.Contrary to this, the intrinsic viscosity ratio [η]/[η] shows independence from the range of degree of polymerization and the origin of cellulose, confirming thus once more the polymeranalogous course of nitration. Its value referred to a degree of substitution S = 2.90±0.02, to absolute dry and pure cellulose and to standardized viscosity measurements amounts [η]Ac/[η]CuEn = 1.95±0.05. Determination of the intrinsic viscosity ratio permits, therefore, to obtain information in respect of the polymeranalogous and homogeneous character of the cellulose nitrate, and, in connection with determinations of yield of nitration, in respect of the purity of the corresponding unsubstituted cellulose.Basing on the constant value of the intrinsic viscosity ratio [η]Ac/[η]CuEn, and using the quotients [η]FeTNa/[η]CuEn and [η]CdEn/[η]CuEn, there has been derived the [η]‐DP‐relationships for unsubstituted cellulose in the respective solvents.
Asymmetrische Umkehrosmose‐Membranen aus den Reihen der aromatischen Polyamide und Polyamidhyrazide
Authors: Zschocke P. , Strathmann H. 
Published: April 2003

AbstractAus aromatischen Polyamiden und Polyamid‐Hydraziden lassen sich asymmetrische Umkehrosmose‐Membranen herstellen. Polyamid‐Membranen weisen bei Druckfitration bei 100 bar Kochsalz zu mehr als 99% zurück, während Polyamid‐Hydrazid Membranen unter gleichen Bedingungen, bei quantitativem Rückhaltevermögen für MgSO4, Kochsalz nur zu 90 bis 98% zurückweisen. Herstellung und Eigenschaften dieser Membranen werden beschrieben.
Acroleindiethylacetal: Reaction with free radicals and copolymerization
Authors: Sastre Roberto , Mateo José L. , Acosta José 
Published: April 2003

AbstractThe reaction between acroleindiethylacetal (3.3‐diethoxypropene) and free radicals and the behaviour of this acetal in the free radical copolymerization with unsaturated monomers has been investigated. The decomposition of benzoyl peroxide and tert.‐butyl peroxide in acroleindiethylacetal has been studied in the liquid phase. On the basis of the obtained products a mechanism is proposed which involves the abstraction of a hydrogen atom by a primary radical from a carbon atom which is adjacent to oxygen. We also tried to copolymerize the acetal with several conventional comonomers but copolymers were only obtained when acrylonitrile and maleic anhydride were used. The remarkably uniform composition of the copolymers from the acetal and maleic anhydride is explained through a donor‐acceptor complex between the two monomers.
Emulsion polymerization of butadiene and subsequent grafting of methylmethacrylate. High impact properties of blends from this grafted polymer and polyvinylchloride
Authors: Beati E. , Pegoraro M. 
Published: April 2003

AbstractThe paper illustrates the graft emulsion polymerization of methylmethacrylate onto polybutadiene in two steps. In the first butadiene is polymerized using two radical initiators (AIBN and (NH4)2S2O8), whose ratio does not influence the relative amount of 1,2‐, 1,4‐trans and 1,4‐cis structures. The second step uses AIBN only: the grafting yield is very high. Grafting mechanism is discussed. The grafted polymer has good mechanical properties and its blends with PVC present very high impact strength. The mechanical properties are discussed. A statistical copolymer of butadiene and methylmethacrylate was prepared and compared with the grafted polymer. The copolymer is also a very good additive for PVC to elevate its impact strength.
Imprégnation du polypropylène. Conséquences sur ses grandeurs diélectriques
Authors: Boiteux Gisèle , Seytre Gérard , Berticat Philippe , Dubois Jean‐Claude 
Published: April 2003

AbstractLe film de polypropylène beétiré est un diélectrique de plus en plus utilisé dans la fabrication des condensateurs. L'article traite de son imprégnation par des composés polaires en vue d'améliorer ses propriétés diélectriques.
Decomposition of polymerization initiators under high pressures
Authors: Luft Gerhard , Mehrling Peter , Seidl Hans 
Published: April 2003

AbstractA number of diacylperoxides, peroxydicarbonates, peresters and dialkylperoxides with various substituents were chosen to investigate their homolytic decomposition under pressures of up to 3000 bar and high temperatures of up to 200°C, discontinuously in steel autoclaves, in an optical high pressure cell and in flow processes. The measurements, carried out in isododecane as solvent with a peroxide concentration of 1% by weight show that pressure has a strong influence on the decomposition: the half‐life time at 3000 bar is twice that at normal pressure. The pressure dependence, which varies according to the structure of the peroxide and the decomposition mechanism, is interpreted by means of the activation volumes. On the basis of the results, recommendations are made on the choice of peroxides suitable as polymerization initiators for application at high pressures and temperatures.
Zur Molekülgröße von ungehärteten Phenoplasten
Authors: Braun Dietrich , Arndt Johannes 
Published: April 2003

AbstractUnivernetzte Kondensate aus Phenol oder p‐Kresol und Formaldehyd können durch Gelchromatographie an Merckogel® PVA 6000 in bis zu vierzehn Peaks aufgetrennt werden. Die einzelnen Peaks entsprechen einer homologen Reihe von Mehrkernverbindungen, die aus über Methylenbrücken verbundenen Phenol‐bzw. p‐Kresolbausteinen bestehen. Durch Gelchromatographie an Merckogel® 20 000 oder 80 000 kann abgeschätzt werden, wie groß die höchsten Molekulargewichte in den Kondensaten sind, d. h. wie viele Phenolbausteine maximal miteinander verknüpft sind.
Cokatalysatoren für die sauer katalysierte, partielle Cyclisierung von flüssigem cis‐Polybutadien
Authors: Sunder‐Plassmann Paul , Frenzel Peter‐Jürgen , Peitscher Günter 
Published: April 2003

AbstractDer cokatalytische Einfluß von Carbonsäuren und Phenolen auf die Trifluormethansulfonsäure‐katalysierte, partielle Cyclisierung von flüssigem cis‐Polybutadien wird untersucht. Außerdem wird der Einfluß der Reaktionstemperatur im System flüssiges cis‐Polybutadien. Phenol und Trifluormethansulfonsäure untersucht, und zwar im Hinblick auf die miteinader konkurrierenden Reaktinen der Cyclisierung und der Phenolanlagerung bzw. Umlagerung von Phenylethergruppen zu ortho‐und parasubstituiertem Phenol. Hierbei zeigte sich, daß die Temperaturabhängigkeit der Reaktionsgeschwindigkeiten von Cyclisierung und Phenolanlagerung relativ gering ist. Die möglichen Ursachen werden diskutiert.