bluuebunny/crossref_metadata_2025_split huggingface dataset:
Venetzung von Amylose mit Epichlorhydrin, 1. Untersuchung der Phase vor der Gelbildung
Authors: Pfannemüller Beate , Sperlich Marianne 
Published: April 2003

AbstractCross‐linking of amylose with 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) was studied in aqueous 1M NaOH solution in dependence of the amylose concentration, the mole ratio of anhydroglucose to epichlorohydrin, and the degree of polymerization of the primary chains. Structural changes which occur during the pre‐gel phase were followed by chemical analysis, by viscosity and light scattering measurements, and by the optical properties of the iodine complex. The results indicate in the early stage of the process that the introduced glycerol diether groups are mainly present as intermolecular cross‐links as seen from a rapid increase in the molecular weight. With further progress of the reaction a decrease of particle density may be derived from the unusual dependence of intrinsic viscosity and mean square radii of gyration on molecular weight. The results are discussed being due to association of amylose segments by hydrogen bonds in the weakly cross‐linked products and a solubilizing effect of monoether substituents introduced later on.
Viscoelastic spectra of ethylene/propylene copolymers obtained with catalytic systems having a different steric regulation
Authors: De Candia Francesco , Maglio Gianni , Palumbo Rosario , Romano Gennaro , Zambelli Adolfo 
Published: April 2003

AbstractThe dynamic mechanical properties of ethylene/propylene copolymers prepared by soluble catalysts based on vanadium salts and alkylaluminium compounds were investigated. The properties of the copolymers were found to depend not only on the chemical composition, but also on the polymerization temperature and on the stereoregulating character of the catalyst. The mechanistic implications of these findings are discussed.
Intermittierende Laserbeleuchtung für die Interferenz‐ und Schlierenoptik einer analytischen Ultrazentrifuge
Authors: Floßdorf Josef , Schillig Henning , Schindler Klaus‐Peter 
Published: April 2003

AbstractA simple and inexpensive illuminating system is described that improves analytical ultracentrifugation performed with interference and schlieren optics. Its essential part is a modulatable laser synchronized to the rotor speed by the multiplexer of the absorption scanner of the Beckman Model E ultracentrifuge. Particularly in connection with the Rayleigh interference optics, this method combines high fringe contrast and resolution with the advantages of the use of multicell rotors: ease of operation, efficiency and equalness of experimental conditions for each sample in the rotor. Up to six cells can be run simultaneously, but still individual pictures can be taken of each of them. A motor‐driven camera accumulates in an arbitrary sequence up to 250 pictures. This modification has been mainly designed for the Beckman Model E but can also be adapted to other analytical ultracentrifuges.
Synthèse et polymérisation de polyméthacrylates porteurs de la quinine. Etude comparée de la toxicité et de l'immunogénicité des formes libres et polymériques
Authors: Pinazzi Christian , Rabadeux Jean Claude , Pleurdeau Alain , Nivière Pierre , Paubel Jean Pierre , Benoit Jean Pierre 
Published: April 2003

AbstractQuinine was linked to 2‐chlorocarbonyloxyethyl methacrylate (6) by a carbonate bound. This monomer 7 was characterized by usual spectroscopic methods and polymerized by a radical process. The resultant polymer 4 was biologically tested by toxicity and immunology studies on rabbit. Polymer 4 was analyzed by IR and NMR spectroscopy and compared with the polymer obtained by chemical modification of poly(2‐hydroxyethyl methacrylate) (1).
Cyclopolymerization, 7. Radiation induced polymerization of N‐substituted dimethacrylamides in the solid and supercooled liquid states
Authors: Kodaira Toshiyuki , Ni‐Imoto Masaki , Aoyama Fumio , Yamaoka Hitoshi 
Published: April 2003

AbstractThe effect of phases, viz., a crystalline, a glassy, and a supercooled liquid state, on the cyclopolymerization of N‐substituted dimethacrylamides 1, initiated by ionizing radiation, was examined. In both the crystalline and supercooled liquid states, 1 was polymerized to give completely cyclized polymers, whereas no polymerization occurred in the glassy state. The structural investigations showed that the polymerization in the supercooled liquid state afforded polymers with the same structure as that of polymers formed in the liquid state, while the polymerization in the crystalline state yielded polymers with some difference in structure. Irrespective of the matrices where polymerizations were carried out, poly(1) obtained are amorphous, and the rate determining step was found to be an intramolecular cyclization reaction, by ESR spectra of propagating radicals. The results thus obtained suggest that the polymerizations of dimethacrylamides 1 in the solid and supercooled liquid states proceed through a virtually identical mechanism with that developed for the polymerization in the liquid state, but the matrices influence the polymerization process to some extent.
Reaktive träger zur immobilisierung von enzymen ausgehend von polyacrolein
Authors: Manecke Georg , Pohl Robert 
Published: April 2003

AbstractPolyacrolein (1) was transformed into poly(allyl alcohol) (2), poly[1,1‐bis(hydroxymethyl)ethylene] (5) and N‐substituted poly(vinylmethanimine)s 8, 9a–c and 10. By subsequent reactions on these polymers reactive carriers with isothiocyanato‐, diazo‐, and azido groups were formed or by reaction with BrCN activated carriers were obtained which are able to bind enzymes covalently. The binding abilities of some reactive carriers were investigated for papain and trypsin. The effect of the pH‐value during the coupling reaction, the amount of offered enzyme, the content of the reactive groups per g carrier and the effect of different reactive groups on the binding ability of the carriers were investigated. For immobilized papain and trypsin the enzymatic activity, the pH‐optimum of their activity, and the apparent Michaelis constant KM(app) were determined. The dependence of the activity on the temperature was also investigated.
3‐ and 4‐dimethylaminobenzyl acrylate and methacrylate and their polymers
Authors: Hrabák František , Hynková Vlasta , Pivcová Hana 
Published: April 2003

Abstract3‐ and 4‐dimethylaminobenzyl acrylates (3 and 4) and methacrylates (1 and 2) were prepared and their densities, IR and NMR spectra are recorded. In order to evaluate their reactivity towards benzoyl peroxide, the rate constants of the reaction of benzoyl peroxide with 3‐ and 4‐dimethylaminobenzyl alcohols and 3‐ and 4‐dimethylaminobenzyl acetates were determined. The reactivity of the esters prepared in this work appeared to be weaker than that of an N‐aryl‐N‐alkylaminoalkyl methacrylate. The blocks of homopolymers of these esters and of their copolymers (mole ratio 1:1) with styrene and methyl methacrylate are crosslinked. Both homopolymers and copolymers of 1 and 3 are more stable in polar solvents and on heating than polymers of 2 and 4. The copolymerization parameters of 1 and 2 with styrene are close to the copolymerization parameters of methyl methacrylate with styrene.
Coenzyme models 14 Addition reaction of sulfite ion to monomeric and polymer‐bound flavins
Authors: Shinkai Seiji 
Published: April 2003

AbstractRate and association constants (kf and K, respectively) for the addition of sulfite ion to three flavins (including isoalloxazines) and to four flavin‐containing polymers were determined at 30°C in aqueous systems. The forward reaction rates for polymer‐bound flavins at an ionic strength of μ = 0,18 mol/l were enhanced by factors of 15–37 and the association constants by factors of 7–19, compared with those of the corresponding monomeric flavins. A linear log kf – log K relationship was found for monomeric flavins. While the parameters for polymer‐bound flavins deviated to the upper area by 0,5–1,0 log units. An increase in the salt concentration suppressed markedly the reaction parameters for polymer‐bound flavins, and the log kf – logK plot at μ = 0,7 mol/l was involved in the linear relation for monomeric flavins.
The charge‐transfer complex maleic anhydride‐tetrahydrofuran and its role as photosensitizer in the polymerization of methyl methacrylate
Authors: Torres Amelia , Castaño Fernando , Alvariño José M. 
Published: April 2003

AbstractThe formation of a charge‐transfer complex (CTC) between maleic anhydride and tetrahydrofuran both in bulk and in chloroform solution is proved by electronic absorption spectroscopy, and its association constant at 35°C is determined by this technique and by 1H NMR. The effect of irradiation with monochromatic 350 nm light upon the fluorescence spectrum of the CTC excited with this same radiation is studied. Significant changes are noted in the bulk system, but the changes are much smaller in the presence of methyl methacrylate which is simultaneously polymerized. The effect of oxygen on the polymerization is discussed.
Radius of gyration versus molar mass relations from light scattering for polydisperse non‐gaussian chain molecules. Polystyrene in toluene and short DNA‐fragments in aqueous NaCl‐solution
Authors: Oberthür Radulf Christoph 
Published: April 2003

AbstractTheoretical relations for the dependence of the z‐average radius of gyration Rz as a function of the mass average molar mass Mw are derived for expanded coils, persistence coils with persistence of direction, persistence coils with persistence of direction and curvature, and for needles, all exhibiting a Schulz‐distribution of their molar masses. These relations are applied to experimental data from light scattering of polystyrene in toluene and DNA‐Na in aqueous NaCl‐solution of 200 mol NaCl per m3 at room temperature. In the case of DNA it becomes evident that the double helix shows no important persistence of curvature and that the experimental data can be described adequately by a persistence chain with mere persistence of direction and a statistical chain element b = (999±33). 10−10 m, corresponding to a persistence length a = (500±17). 10−10 m.
Die thermische Polymerisation von Methylmethacrylat, 1. Polymerisation in Substanz
Authors: Stickler Manfred , Meyerhoff Günther 
Published: April 2003

AbstractSpecial purification of the monomer and careful preparation of the reaction setup allowed a thorough study of the spontaneous thermal polymerization of methyl methacrylate over a wide range of temperatures (0–140°C). The rates of polymerization are notably lower than the few data previously reported in literature, and the degrees of polymerization slightly higher. The thermal initiation reaction is superimposed by radical production due to the natural ionising radiation (cosmic radiation etc.). This additional initiation becomes significant at temperatures below 60°C. New and more reliable monomer chain transfer constants are given.
Strukturelle Effekte in Systemen MnLi/Butadien/Styrol
Authors: Melenevskaya Elena , Sgonnik Vladimir , Dolinskaya Eleonora , Erussalimsky Boris 
Published: April 2003

AbstractThe structure of the butadiene unit C4H6 in the hydrolysis products of the oligomers RMnC4H6Mm'Li and RMnC4H6Li (where R is sec‐butyl, M and M' are perdeuterobutadiene or styrene) was estimated by the use of IR‐ and NMR‐spectroscopy. The dependency of the C4H6‐structure on the nature of both the preceding unit M and the attacking monomer M' was investigated. The variation of the concentration of the organolithium compounds during the oligomer synthesis on the one hand, and during their hydrolysis on the other hand, showed a dependency of the C4H6‐structure on the conditions of the respective experiments.
Copolymerization of carbon dioxide and epoxypropane by using cobalt(II) acetate and acetic acid
Authors: Soga Kazuo , Hyakkoku Kyoko , Ikeda Sakuji 
Published: April 2003

AbstractThe copolymerization of carbon dioxide and epoxypropane was investigated at 80°C in dioxane by using cobalt(II) acetate as catalyst in the presence of acetic acid. The addition of acetic acid hardly diminishes the copolymer yield, but the number average molecular weight of the copolymer decreases in proportion to the concentration of acetic acid. The 1H NMR spectrum of the copolymer displays a very strong peak due to the methyl protons attached to an ester carbonyl group (OCOCH3). From these results it has been concluded that acetic acid causes a transfer reaction which leads to acetoxy end groups (cf. Eq. (14) below). Some other carboxylic acids, such as C6H5COOH, ClH2CCOOH, Cl2HCCOOH etc., were found to cause similar transfer reactions, too.
Cyclo‐copolymerization of 1,6‐diene with monoolefin, 2. The copolymer composition equation and the relative rates of addition in the cyclo‐copolymerization of diallyl ether with maleic anhydride and fumaronitrile
Authors: Fujimori Kiyohisa 
Published: April 2003

AbstractA copolymer composition equation is derived for the cyclo‐copolymerization of a 1,6‐diene with a monoolefin that do not homopolymerize. The theory is applied to the free radical copolymerization of diallyl ether (DAE) with maleic anhydride (MA) and to that of DAE with fumaronitrile (FN). Both systems fall in the special case where there are no unreacted CC bonds left in the copolymer. The copolymer compositions are between 1:1 and 1:2 (=[diene]:[monoolefin]) over a wide range of monomer feed composition. The reactivity ratios obtained from the equation indicate that for the DAE/MA system, the intramolecular cyclization of the uncyclized DAE radical is 2,9 times more effective than the addition of MA monomer to the uncyclized DAE radical, and that for the system of DAE/FN, the intramolecular cyclization of DAE radical is 6,7 times more effective than the addition of FN monomer.
Bestimmung physikalischer konstanten durch die funktion y/x = a + b·x in der lösungsviskosimetrie, ebulliometrie und dampfdruckosmometrie
Authors: Melsheimer Jörg , Scotobayashi Hideto 
Published: April 2003

AbstractCalculations of most probable values on the basis of the equations y = a · x + b · x2, y/x = a + b · x and x = a* + b* · y/x have been carried out with data from solution viscometry, ebulliometry, and vapor pressure osmometry. The calculations carried out with the method of least squares give different coefficients for the equations taken as a basis. However equal coefficients are obtained with the method of Deming in which the measured data are weighted. Furthermore the so calculated slopes of the equations differ from those determined by the method of least squares whereby the differences depend upon the type of equations and upon the deviation of the measured data.
Effects de la substitution du cycle pyrrolidone‐2 par un groupement méthyle sur le processus de polymérisation
Authors: Deratani André , Sekiguchi Hikaru 
Published: April 2003

AbstractWe tried to evaluate the reason for the very low polymerizability of methyl derivatives of 2‐pyrrolidone in the presence of anionic polymerization catalysts. The polymerizability estimated from the influence of the methylated group on the reactivity of the lactam ring (steric, inductive, and thermodynamic factors) does not agree with the experimental results of homopolymerization and copolymerization of 2‐pyrrolidone. The substitutional effects on the propagation process were analyzed and an explanation which is based on the slow‐down of the molecular growth and the crystallization of the reaction mixture is proposed. Thus, in copolymerizations with a small percentage of substituted lactams, the propagation is very slow with regard to the crystallization, which would allow a quick encagement of the active site by hydrogen bonds, and lead to the spontaneous blocking of polymerization. If this percentage increases, the crystallization cannot take place, and this would, as a consequence. favor all the secondary reactions leading to the formation of bicyclic dimer and oligomers.A “chain multiplication” reaction was found in some cases.
Charge‐transfer complex between p‐oxathiene and maleic anhydride and its relative reactivity in alternating copolymerization
Authors: Iwatsuki Shouji , Itoh Takahito 
Published: April 2003

AbstractCharge‐transfer complex formation and alternating copolymerization of p‐oxathiene (POT)‐maleic anhydride (MAnh) system were studied. Relative reactivity of POT‐MAnh complex was obtained from three kinds of terpolymerizations. For example, in terpolymerization of POT, MAnh and acrylonitrile (AN), monomer reactivity ratios of POT‐MAnh complex and AN were found as r1 (complex)=55,8 and r2 (AN)=0,0176 at 60°C. POT‐MAnh, p‐dioxene‐MAnh and vinyl ether‐MAnh systems were compared in relative reactivity and some physical properties concerning charge‐transfer complex. The reactivity of those MAnh complexes was found to be controlled more significantly by some properties related to electron‐donating power of donors rather than by resonance and polarity terms of separate donor monomers.
Regular copolyamides, 7. Water absorption in regular copolyoxamides
Authors: Tirrell D. , Grossman S. , Vogl O. 
Published: April 2003

AbstractWater absorption at 93% relative humidity and 25°C was determined for 12 regular aliphatic/aromatic copolyoxamides. The equilibrium water absorption ranges from 7% to 30%, varied with the polymer structure and is highest in polymers with high amide concentration. The water absorption is reversible and seems to consist of a two‐step process, rapid absorption of water by polymer followed by a slower second stage as equilibrium is approached. These polymers have low crystallinity and the water absorption does not occur in crystalline regions. All water is bound to the polymer; it may be freed by heating the hydrated polymer above 100°C, but rebinds completely at room temperature.
Sequenzlängenverteilungsanalyse der 1,2‐Einheiten in Polybutadienen an Hand der Olefin‐Polymeres/Metathese‐Reaktion; ein Weg zur Darstellung von mono‐ und disubstituierten Cyclopenten‐ wie auch Cyclohexen‐Verbindungen
Authors: Thorn‐Csányi Emma , Perner Helmut 
Published: April 2003

AbstractBy means of metathetical degradation of polybutadienes it is possible to determine 1,4‐B‐(1,2‐B)1–3‐1,4‐B sequences. The metathetical 1,2‐butadiene (1,2‐B) sequence lengths distribution analysis may be used for the synthesis of substituted cyclopentene and cyclohexene derivatives.
Kinetics of inhibited or retarded polymerization. Investigations on the cerium(IV)/toluene/acrylonitrile system
Authors: Singh Baishnab C. , Misra Basanta K. , Rout Anuradha , Mallick Nigamananda , Rout M. K. 
Published: April 2003

AbstractThe kinetics and mechanism of the inhibiting action of toluene on the Ce(IV) initiated polymerization of acrylonitrile were studied together with the effects of [M], [Ce(IV)], [Toluene], [HClO4], [NaClO4], and [Acetic acid] on the rate of polymerization. The values of composite rate constant kkt/kpkoki for toluene (and substituted toluenes) was calculated by plotting [M]/Rp versus [M]−1. A very significant observation in the present study was that the plot of [M]/Rp versus [M]−1 gave a negative intercept, which seems to be a general observation for all inhibiting substrates. On the basis of the experimental data, it could be concluded that the benzyl radical obtained by hydrogen abstraction, and not a chain transfer, is responsible for the inhibition.
Chemische synthese verzweigter polysaccharide, 7. Zur frage des abbaus der polysaccharid‐hauptkette bei verzweigung über glykosidische bindungen
Authors: Pfannemüller Beate , Berg Annette 
Published: April 2003

Abstract6‐Trityl‐2,3‐dicarbanilyl and 2,3‐dicarbanilyl derivatives of amylose and cellulose have previously been used as a backbone to introduce oligosaccharide branches by (1 → 6) glycosidic bonds. Possible degradation prior and during the glycoside coupling was now followed by light scattering measurements on each step of derivatization. The results obtained with derivatives of technical and synthetic amyloses indicate that some degradation may occur in the tritylation reaction and possibly in the conversion to the 6‐trityl‐2,3‐dicarbanilate. In the following steps, e.g. detritylation and glycosidic condensation of glucose and maltose derivatives under the conditions applied, degradation appears to be almost absent. In corresponding studies with cellulose derivatives problems arise mainly in the tritylation step. The results of the light scattering and viscosity measurements are discussed with respect to the molecular conformation.
Stereoselection in the polymerization of racemic propylene sulfide
Authors: Marchetti Massimo , Chiellini Emo , Sepulchre Maurice , Spassky Nicolas 
Published: April 2003

AbstractElution with different solvents of high molecular weight polymers of racemic propylene sulfide, prepared by stereospecific catalysts and supported on optically active polymers such as poly[(S)‐3‐methyl‐1‐pentene] and poly[(L‐dilactide)], makes it possible to separate polymeric fractions having opposite optical rotation in the former case, whereas in the latter no selective separation occurs. Although the degree of separation is less than 5%, mainly due to the poor efficiency of the separation process (5%), it is possible to recognize the cadmium tartrate catalyst as more efficient with respect to diethylzinc/racemic diol system in the stereoselective polymerization of propylene sulfide. The use of an optically active diol in the latter system promotes a stereoselection comparable to that of the former system, thus substantiating the specific role of heterogenous catalytic sites in controlling the stereochemistry of the chain propagation.
The temperature coefficient of the unperturbed dimensions of poly(pentachlorophenyl methacrylate)
Authors: Radic Deodato , Gargallo Ligia 
Published: April 2003

AbstractValues of the temperature coefficient of the mean square unperturbed dimensions dln(r/dT) for poly(pentachlorophenyl methacrylate) are obtained from viscosity vs. temperature data under two different conditions: (a) viscosity determinations in several different solvents each at its Θ‐temperature and (b) viscosity determinations in a thermodynamically good solvent with a similar chemical structure as compared to the repeating unit. An anomalous temperature dependence of the viscosity was observed in o‐dichlorobenzene for this polymer. The results obtained from both conditions are compared and their limitations and interpretations are discussed.
Über Polyarylenalkenylene und Polyheteroarylenalkenylene, 9. Synthesen und Charakterisierung von Poly(5‐methylthiazolo‐[4,5‐f] benzthiazolium‐2,6‐diylvinylenarylenvinylen)en und einigen Modellverbindungen
Authors: Koßmehl Gerhard , Bocionek Peter , Manecke Georg 
Published: April 2003

AbstractStarting from 2,3,6‐trimethylthiazolo[4,5‐f] benzothiazolium perchlorate (2b) some poly(5‐methylthiazolo[4,5‐f] benzothiazolium‐2,6‐diylvinylenarylenevinylene)s (11a–c) and some corresponding model compounds (10a–c) were prepared via Knoevenagel condensation with mono‐and dialdehydes (4 and 6) of the benzene and thiophene series. Additional series of model compounds (5a–c, 7a–c, 8a–f, and 9a–f) were obtained from 2,3,6‐trimethylthiazolo[4,5‐f]benzothiazolium iodide (2a) or 2,3‐dimethylbenzothiazolium iodide (3a), respectively, or from the perchlorates (2b and 3b) submitted to the same reaction with mono‐and dialdehydes. The structure of these model compounds and polymers was confirmed by elemental analyses, IR and electronic spectra. The model compounds are also characterized by their mass spectra, and in the case of sufficient solubility by 1H NMR spectroscopy too. The electrical conductivities of all compounds and polymers and the thermooxidative degradation of the polymers were investigated.