bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rotationsebulliometer, 1. Prüfung der Apparatur
Authors: Sotobayashi Hideto , Asmussen Frithjof , Chen Jiang‐tsun 
Published: April 2003

AbstractA new pressure controlled twin‐ebulliometer without Cottrellpump is described. The apparatus is equipped with rotating vessels to establish complete equilibrium between liquid and vapour. The boiling temperature can be chosen by reducing the pressure by means of a pressure regulator in the range of 100–760 Torr.In SI‐Einheiten: 1 Torr=133,322 N/m2.
The elevation of the boiling‐point is measured by two thermistors in a Wheatstone bridge circuit.Investigation of benzil and biphenyl in dilute benzene solution shows that the rotating ebulliometer permits operations within a boiling temperature range of 30–80°C.Measurements of polystyrene and poly(ethylene glycol) [poly(oxyethylene)] in benzene solution show that the rotating boiling vessel avoids the formation of foam. Therefore, the elevation of the boiling‐point of solutions of polymeric samples can be measured with this apparatus.
Studies on the polymerization of vinyl compounds in the presence of metal salts, 11. The polymerization of methyl methacrylate initiated by ferric ion and thiourea or its derivatives
Authors: Narita Hiroshi , Otsuki Atsuko , Machida Seishi 
Published: April 2003

AbstractThe polymerization of methyl methacrylate initiated by ferric salt and thiourea in dimethyl sulfoxide solution was studied. By the substitution of hydrogen by an alkyl or aryl group in the thiourea, the rate of the polymerization decreases. The logarithm of the rate is proportional to the σ* value of Taft's equation. The results are discussed on the basis of the IR and NMR data. It was confirmed that the polymerization is initiated by a radical produced by the reaction of the ferric ion with the isothiourea which is formed from the thiourea by tautomerization. The termination of the polymerization is also discussed based on the results of kinetic studies with different kinds and concentrations of the ferric salt.
Free‐radical polymerization of methyl methacrylate initiated by N,N‐dimethylaniline
Authors: Ishida Tomohiro , Kondo Shuji , Tsuda Kazuichi 
Published: April 2003

AbstractN,N‐Dimethylaniline (DMA) does initiate the free‐radical polymerization of methyl methacrylate (MMA), methyl acrylate, and methyl vinyl ketone. The overall rates of polymerization of MMA were obtained at 40, 50, and 60°C. From the results of a detailed kinetic investigation, the activation enthalpy and activation entropy of polymerization were calculated as 63,2 kJ mol−1 and −153 J mol−1 K−1 at 60°C. Rate equation was also obtained as Rp = k[DMA]1/2[MMA]3/2 and the polymerization was inhibited by benzoquinone. Though styrene alone was not polymerized by DMA, the copolymerization of MMA with styrene by DMA (reactivity ratios: rMMA=0,45 and rSt=0,50) followed a typical free‐radical mechanism. An electron‐transfer complex between DMA and MMA is proposed as the initiation species.
Influence d'une différence de réactivité entre hydroxyles primaires et secondaires sur la gélification de systèmes polyol/polyacide
Authors: Durand Dominique , Bruneau Claude‐Marcel 
Published: April 2003

AbstractUsing a new general formulation of Flory's gelation criterion, a critical transition equation is derived for polyol/polyacid systems having hydroxyl groups of unequal reactivity. The reaction probabilities of various hydroxyl groups are formulated from kinetic calculations. The gelation equation shows that the inclusion of monomers having groups of unequal reactivity significantly increase the extent of reaction necessary for the gelation. The theoretical forecasts are confirmed by the experimental study of some polyester systems.
On the copolymerization of polar vinyl monomers with electron donor monomers catalyzed by ethylaluminium dichloride
Authors: Florjańczyk Zbigniew , Kuran Witold , Pasynkiewicz Stanisław , Langwald Norbert 
Published: April 2003

AbstractThe copolymerizations of acrylonitrile and methyl acrylate with propylene, isobutylene, butadiene, styrene, and vinyl chloride and the copolymerizations of methacrylonitrile and methyl methacrylate with propylene in the presence of ethylaluminium dichloride as the complexing agent were studied. When the polar vinyl monomer is not completely complexed by ethylaluminium dichloride in the copolymerizations of acrylonitrile with propylene, isobutylene, and vinyl chloride, and in those of methacrylonitrile and methyl methacrylate with propylene, copolymers rich in polar vinyl monomer were found. In the copolymerization of acrylonitrile with propylene, the polar vinyl monomer content in the copolymer was found to increase with decreasing mole ratio ethylaluminium dichloride/acrylonitrile in the monomer feed. In the copolymerizations of acrylonitrile and methyl acrylate with butadiene and styrene and of methyl acrylate with propylene, isobutylene, and vinyl chloride, copolymers of approximately 1:1 composition are formed. The reactivity of monomers is discussed. The introduction of VOCl3 to the polymerization systems studied was found to cause an enhancement in the copolymerization yield and a decrease of the copolymer intrinsic viscosity; it has not, however, a significant influence on the copolymer composition.
Polymerization of lactams, 23. Non‐activated polymerization of 2‐pyrrolidone initiated with potassium tert‐butoxide
Authors: Roda Jan , Kmínek Ivan , Králíček Jaroslav 
Published: April 2003

AbstractThe non‐activated polymerization of 2‐pyrrolidone initiated with potassium tert‐butoxide (conc. range 0,24–4,97 mole‐%) was studied at 40°C. In accordance with theory, the conversion increases linearly with polymerization time and with initiator concentration. The linear dependence on conversion of the content of basic groups in the polymer and, above all, of the number of polymer molecules, and its independence on the initiator concentration up to 30% conversion indicate that a stationary state between formation and destruction of growth centres is very rapidly reached.
Kinetics and mechanism of the polymerization of cyclic acetals, 5. Spectroscopic studies of the polymer end‐groups in poly(1,3‐dioxolane)
Authors: Kubisa Przemysław , Penczek Stanisław 
Published: April 2003

AbstractPolymerization of 1,3‐dioxolane (1) was initiated in CH3NO2 and CH2Cl2 solvents with benzoylium hexafluoroantimonate (C6H5CO+SbF), terminated with sodium ethanolate (C2H5ONa), and the endgroups were determined by using UV spectrophotometry and 1H NMR methods. Polymers with high polymerization degrees DPn were obtained (M̄n up to 3·105); DPn calculated for living polymerization conditions (DPn=([1]0−[1]e)/[C6H5CO+SbF]0; i.e. one molecule of initiator gives one macromolecule) agree well with DPn measured by osmometry and DPn found from 1H NMR and UV methods assuming one respective end‐ group per macromolecule. 1H NMR studies were performed on polymers from perdeuterated 1 (1,3‐dioxolane‐d6). These polymers, after purification, were shown to bear benzoyloxy and ethoxy end‐groups: \documentclass{article}\pagestyle{empty}\begin{document}${\rm C}_6 {\rm H}_5 \hbox{---} {\rm CO\rlap{--} (O} \hbox{---} {\rm CD}_2 {\rm CD}_2 {\rm OCD}_2 {\rm \rlap{--} )}_n {\rm OCH}_2 {\rm CH}_3$\end{document}Similar results were obtained for polymers initiated with triethyloxonium hexafluoroantimonate ((C2H5)3O+SbF), and terminated with triphenylphosphine ((C6H5)3P). These results indicate that initiation with stable oxocarbenium or oxonium ions leads to predominantly linear macromolecules, while initiation with perchloric acid (according to the data reported by Plesch) leads to polymers of low molecular weight and claimed to be mostly cyclic after killing with C2H5ONa.
Functional monomers and polymers, 43. ESR study on the copper(II) complexes of polymers containing imidazolyl groups and of their monomeric analogs
Authors: Sato Masaaki , Kondo Koichi , Takemoto Kiichi 
Published: April 2003

AbstractESR spectroscopy was conducted on Cu(II) complexes of poly(1‐vinylimidazole), poly[4(5)‐vinylimidazole], and poly(2‐methyl‐1‐vinylimidazole) and compared with those of the corresponding low‐molecular‐weight Cu(II) complexes. At 293 K, an averaging of the anisotropy was observed for monomeric [Cu(imidazole)4]2+ complex, however, it was not for polymeric Cu(II) complexes. On the other hand, both monomeric and polymeric complexes showed typical asymmetric spectra of Cu(II) complex in a tetragonal coordination at 77K. Structure of the intramolecular [CuL4]2+ type of polymeric complexes was kept stable in the case if the ligand L to Cu(II) mole ratio was over 10:1, but it tended to change by increasing the pH value of the systems, with a conformational change of the polymeric ligand in aqueous solution. A distorted form was suggested for the polymeric Cu(II) complexes at lower pH.
Solution properties of poly(alanine)s, 3. 1H NMR study of poly(alanine)s in the mixture of chloroform and trifluoroacetic acid
Authors: Shoji Akira , Kawai Toru , Nishioka Atsuo 
Published: April 2003

AbstractThe 1H NMR spectra were studied for monodisperse alanine oligopeptides (dimer, trimer, tetramer, and nonamer) containing a butylamino group at the C‐terminal residue and for copolypeptides of D‐ and L‐alanines having sharp molecular weight distributions. The solvents used were the mixtures of deuterochloroform (CDCl3) and trifluoroacetic acid (TFA) in various compositions. The conformational transformation of poly(L‐alanine)s and the interaction between the NH protons in the oligomers and the solvents were investigated on the basis of the chemical shifts of the NH signals. For the tetramer and the nonamer, the NH protons showed “double peaks” in the compositions of helix‐supporting solvents. The most substantial change in the chemical shifts of the NH peaks occurs between the nonamer and poly(L‐alanine) with a number average degree of polymerization DPn=16, suggesting that the nature of the double peaks observed in poly(L‐alanine)s is essentially different from that observed in oligo‐L‐alanines. This finding is explained in terms of the conformational change which arises from the interaction (solvation) of NH protons with CDCl3 or TFA for the oligomers (below the nonamer) and in terms of the low transitional rate by chemical exchange for poly(L‐alanine)s.
Photochemical reactions and stabilizing properties of 2,6‐Di‐tert‐butyl‐4‐methylphenol, 1. Photochemical reactions of 2,6‐Di‐tert‐butyl‐4‐methylphenol in hexane solutions
Authors: Kowal Joanna , Waligóra Bolesław 
Published: April 2003

AbstractPhotochemical reactions of 2,6‐di‐tert‐butyl‐4‐methylphenol (3) in hexane solutions lead to the formation of 2,6,2′,6′‐tetra‐tert‐butyl‐4,4′‐ethylenediphenol (1) and 2,6,2′,6′‐tetra‐tert‐butyl‐4,4′‐ethanediylidenedi(2,5‐cyclohexadien‐1‐one) (2) in a mole ratio of 10:1 in the first step. The formation of acetophenone due to the decomposition of di(α,α‐dimethylbenzyl) peroxide (dicumyl peroxide) (6) is inhibited by 3 in hexane solution. The inhibiting effect of 3 is greater if the reaction is initiated by light absorbed by 6 than when it is initiated by light absorbed by both 3 and 6.
Gelchromatographie mit zwei Detektoren. Ein verfahren zur Korrektur von Gelchromatogrammen
Authors: Berger Knut C. 
Published: April 2003

AbstractThe relationship between the experimental function E(v) for the viscosity and the chromatogram after correction of instrumental spreading, w(v0) can be expressed by the integral equation

where v0 is the elution volume under the integral sign and D(v, v0) is a function that describes the shape of the band spreading curve of a monodisperse sample. The relationship between the experimental chromatogram e(v) is given by the Tung equation. If the function D(v, v0) is independent of the molecular weight, then it is possible to solve these equations simultaneously and to calculate the functions w(v0) and D(v, v0). A mathematical method is given.
Solvent effect on the formation of poly(methacrylic acid)‐poly(N‐vinyl‐2‐pyrrolidone) complex through hydrogen bonding
Authors: Ohno Hiroyuki , Abe Koji , Tsuchida Eishun 
Published: April 2003

AbstractAn interpolymer complex can be obtained by mixing the solutions of poly(methacrylic acid) and poly(N‐vinyl‐2‐pyrrolidone). Three phase changes were observed on increasing the initial polymer concentration: namely, a homogeneous solution, a precipitate, and a gel. Such interpolymer complex formations were examined in several protic and aprotic solvents. The obvious relationship between the complex formation and the dielectric constant of the solvent was eludicated. The effect of hydrophobic interactions on the complex formation was also discussed as well as the role of the α‐methyl group of poly(methacrylic acid).
Elektrokinetische untersuchungen an Fasern, 3. Zur Beurteilung von Modellen für Faserpfropfen und der Einstellzeit von Strömungspotential und Strömungsstrom
Authors: Aichele Wilfried , Schollmeyer Eckhard , Herlinger Heinz 
Published: April 2003

AbstractThe present paper shows that the conductivity of an arrangement of fibres in a liquid depends rather insensitively on the zeta‐potential (ζs) calculated according to the Smoluchowski equation. The reason suggested also makes doubtful the theoretical deduction of the Fairbrother‐Mastin method to correct the porosity dependence of the ζs‐potential.An investigation of the porosity dependence of the three independent coefficients of the phenomenological equations of arbitrary fibres gives an explanation for the fact, that this relation is found to fit in the most cases with the porosity dependence of the ζs‐values. A different arrangement of fibres forming a plug shows that the use of the Smoluchowski equation cannot be expanded from capillaries to plugs using simple corrections.Finally the time dependence of the streaming current and the streaming potential is discussed and compared with the velocity of the streaming fluid and with the electrical properties of the measuring cell.
Functional monomers and polymers, 44. A modified way to form the deoxycholic acid/2,3‐dimethyl‐1,3‐butadiene canal complex and its polymerization
Authors: Miyata Mikiji , Takemoto Kiichi 
Published: April 2003

AbstractDeoxycholic acid/2,3‐dimethyl‐1,3‐butadiene canal complex was found to be prepared readily by replacing various sorts of guest molecules in the deoxycholic acid canals by 2,3‐dimethyl‐1,3‐butadiene monomer. Post‐irradiative polymerization of the monomer included in deoxycholic acid canals was studied after irradiating with γ‐rays from a 60Co source. Both the replacement and the polymerization processes were observed by differential thermal analysis (DTA), thermogravimetry (TG), and IR spectroscopy. The optimum conditions for the replacement of acetone, ethyl acetate, and acetic acid by 2,3‐ dimethyl‐1,3‐butadiene were established.
Polymerization of vinyl ethers by 3d‐transition metal oxides
Authors: Biswas Mukul , Kabir Gazi M. Ahsanul , Bhagawan Suggu Surya 
Published: April 2003

AbstractStudies on the relative efficiencies of 3d‐transition metal oxides as catalysts for the polymerization of vinyl ethers revealed that V2O5 is the most efficient catalyst. Some kinetic studies with the system isobutyl vinyl ether/V2O5/benzene were carried out at ambient temperature. It was found that the rate is second order in isobutyl vinyl ether (IBVE) concentration (0,25 to 2,0mol.1−1) and the inhibition of the polymerization by pyridine suggests a cationic mechanism. Rp increases by the use of benzaldehyde along with V2O5, whereas water (3.10−3mol.1−1) seems to have no effect on Rp. Over the temperature range of 15 to 60°C, Rp as well as [η] attain a maximum value at about 32°C. [η] is unaffected by varying the amounts of oxides, whereas it increases with increasing IBVE concentration. No stereoregularity in the product polymer was observed by using V2O5 alone or in combination with modifiers such as benzaldehyde or carbon disulfide. The kinetics are interpreted in terms of the Hinshelwood‐Langmuire mechanism assuming a single point adsorption.
Radical copolymerisation of vinylidene chloride and methacrylonitrile, 1. Sequence microstructure measured by 220 MHz 1H NMR
Authors: Suggate John R. 
Published: April 2003

AbstractThe radical copolymerisation of vinylidene chloride and methacrylonitrile in bulk and in cyclohexanone solution was studied. The monomer dyad sequence distributions and some of the tetrad and hexad sequences were obtained from 220 MHz 1H NMR spectra of the copolymers. From the copolymer compositions and sequence information it could be shown that the copolymerisation kinetics deviate from the simple Mayo‐Lewis scheme. Small differences were found between the bulk and solution copolymerisations.
The phenyl group motion in polystyrene and a model of restricted internal rotation
Authors: Gronski Wolfram , Murayama Nobumichi 
Published: April 2003

AbstractThe 13C NMR relaxation functions are calculated for the case of restricted rotational diffusion of a CH dipole pair about an internal rotational axis. The model is applied to the interpretation of recent 13C experiments of polystyrene in a region where the relaxation of all C atoms of the phenyl ring exhibits the same temperature coefficient. It is concluded that the velocity of the phenyl group motion may be overestimated if complete rotation is assumed. By means of the model of restricted internal rotation one finds D/D0<0,1 for the ratio of internal and mean segmental rotational diffusion constants.
Pharmacologically active polymers, 17. Syntheses and characterization of polymeric derivatives of the antitumor agent methotrexate
Authors: Przybylski Michael , Fell Elke , Ringsdorf Helmut , Zaharko Daniel S. 
Published: April 2003

AbstractSynthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N‐[4‐(N‐methyl‐2,4‐diamino‐6‐pteridinylmethylamino)benzoyl] glutamic acid (1a), a widely used antitumor agent, are described. Derivatives of poly(L‐lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3–15 mole‐%) of substituted repeating units were prepared by polymer‐analogous amidation and transesterification of the dimethyl ester of 1a and with N‐[2‐(N‐methylmorpholinio)ethyl]carbodiimide p‐toluenesulfonate as coupling reagent. By nucleophilic addition reactions of the pteridinyl amino groups under mild conditions, 1a was bound without cross‐linking to divinyl ether‐maleic anhydride (DIVEMA) copolymers of various molecular weights. This copolymer appeared to be of particular interest as carrier because of its established antitumor and immune‐stimulating activity.—With the exception of the poly(vinyl alcohol) derivative, all polymers containing the 1a residue are water soluble at the physiological pH range. Besides the dimethyl ester of 1a used as convenient starting material for polymer‐analogous reactions, further dialkyl esters of 1a were synthesized as low molecular weight model compounds for the study of the pharmacodynamic properties of polymers, substituted with 1a. The polymeric derivatives of 1a were purified by membrane filtration, solvent extraction, and reprecipitation; the polymers and the dialkylesters 1b–d were characterized by thin‐layer chromatography, IR, NMR, UV and mass spectra, and elemental analysis. Preliminary results of the pharmacological studies with the DIVEMA derivatives of 1a are also reported.
Mass spectrometrical behavior of hydrocarbons, 2. Oligododecenylenes and corresponding alkanes
Authors: Höcker Hartwig , Riebel Klaus 
Published: April 2003

AbstractThe mass spectra of cycloolefins (C12xH22x), cycloalkanes (C12xH24x), and unbranched alkanes are compared. The most prominent fragmentation series are CnH2(n–p)−1⊕, CnH2n − 1⊕, and CnH2n+1⊕, respectively. The intensity of the molecular ion peak decreases in the order given.
Composition dependence of the second virial coefficients for styrene/butadiene/styrene three‐block copolymers and for mixtures of the respective homopolymers
Authors: Sikora Antonín , Pouchlý Julius 
Published: April 2003

AbstractThe composition dependences of the second virial coefficients for styrene/butadiene/styrene three‐block copolymers with Mn≈ 105 g.mol−1 were measured in toluene, 1,4‐dioxane, isobutyl methyl ketone and isopropyl acetate at various temperatures; analogous measurements were made with mixtures of polystyrene and polybutadiene in toluene and 1,4‐dioxane. The results were qualitatively compared with model calculations based on the relations derived by means of the perturbation theory.
Optically active vinyl polymers containing fluorescent groups, 3 synthesis and characterization of optically active polymers containing carbazolyl groups
Authors: Chiellini Emo , Solaro Roberto , Ledwith Anthony 
Published: April 2003

AbstractSyntheses and characterizations of polymers from the optically active vinylcarbazole derivatives (S)‐3‐sec‐butyl‐9‐vinylcarbazole (1), (S)‐9‐(2‐methylbutyl)‐2‐vinylcarbazole (2), and (S‐9‐(2‐methylbutyl)‐3‐vinyl‐carbazole)(3) are described in detail. The N‐vinyl derivative 1 gives satisfactory conversions to high polymers in the presence of both radical and cationic initiators whereas the C‐vinyl derivatives 2 and 3 give better results with ionic initiators (anionic and cationic respectively). Measurement of optical rotation and circular dichroism (CD) for all the polymers as well as corresponding monomers and low molecular weight analogs indicates that the stereochemical placements of monomeric units in the macromolecules are dependent on the type of initiators used.
Theoretical considerations on the formation of graft copolymers by coupling reaction
Authors: Ishizu Koji , Fukutomi Takashi , Kakurai Toshio 
Published: April 2003

AbstractThe effects of various factors on the rate constant of each addition step for the formation of graft copolymers by coupling reactions were considered theoretically. The progressively decreasing rate constant of the addition was considered as a problem of the segment density of branched chains around the functional groups of the backbone molecule, assuming that the spacial distribution of the segments is in equilibrium and the formation of the graft copolymer follows a Markovian process. The rate constant of each stage obtained in coupling of the polystyryl anion with chloromethylated polystyrene was compared with the results derived from the theoretical treatment. These results are discussed in some detail.
The photo‐decomposition of polystyrene containing in‐chain peroxide links.—solvent effects
Authors: Weir Neil A. , Milkie Terence H. 
Published: April 2003

AbstractThe photodegradation of styrene‐oxygen copolymers on irradiation with ultra violet light (λ>300 nm) has been studied using a range of solvents. Rates of degradation of the copolymers are dependent on the solvent. An investigation of the contributing factors to the effect of solvent on the rate of chain scission has been made and a correlation between degradation rate and the reactivity of the solvent as a transfer agent has been observed. Other factors, including solution viscosity appear to be relatively unimportant.
Reaktive mikrogele, 8. Anionische polymerisation von ethylendimethacrylat
Authors: Straehle Wolfgang , Funke Werner 
Published: April 2003

AbstractBy polymerisation of ethylene dimethacrylate with n‐butyllithium in solution reactive microgels have been obtained. These EDMA‐microgels are nearly spherical, have a broad distribution and are easily swellable in organic solvents. The macrogelation depends on the amount of solvent between the microgel particles.