bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graft copolymerization of methyl methacrylate on chlorinated natural rubber, 1. Initiation by various organometallic complexes
Authors: Nogues P. , Dawans F. , Maréchal E. 
Published: April 2003

AbstractMetallic compounds able to abstract chlorine atoms are investigated for initiating the graft copolymerization of methyl methacrylate on chlorinated natural rubber. An improved method for the separation of the side homopolymer from the graft copolymer is described. The cumulative results demonstrate the greater graft efficiency of the new initiating systems than of the usual free radical initiators.
The γ → α partial transformation in nylon 12 by drawing
Authors: Ishikawa Toshihiko , Nagai Susumu , Kasai Nobutami 
Published: April 2003

AbstractPartial development of the α form crystals in γ nylon 12 has been found to take place by drawing near the melting point. The confirmation of the α form has been made by X‐ray diffraction, infrared absorption, and differential scanning calorimetry. The amount of the α form varies depending upon the temperature of drawing and draw ratio, whereas it is almost independent of the rate of drawing. The minimum draw ratio necessary to yield the α form increases as the temperature of drawing decreases. The crystallinity, determined from the density, also increases with the increase in the temperature of drawing and draw ratio, while it decreases slightly with the increase in the rate of drawing. The development of the α form is ascribable to the transformation from the γ form rather than the crystallization from the amorphous region. The total figure of the polymorphism in nylon 12 is proposed.
A theoretical study on the 1H NMR chemical shift of alanine oligopeptides
Authors: Asakura Tetsuo 
Published: April 2003

AbstractAll the NH and α‐CH proton chemical shifts of alanine oligopeptides (Ac‐(Ala)n‐NHMe, where n = 1–6) with extended and α‐helical conformations and anti‐parallel β pleated‐sheet structure, were calculated by taking into account the magnetic anistropy effect due to the CO and two kinds of CN bond anisotropies, and the electric‐field effect. The observed spectral behavior of the NH or CH protons in Ac‐Ala‐NHMe and Ac‐(Ala)2‐NHMe could be mostly predicted from the calculation, which indicates that the NH and CH chemical shifts in these oligomers are mainly determined by the intramolecular shielding effect. On the other hand, the appearance of the “doublet α‐CH peak” for oligomers with chain lengths of five or more reported by Goodman et al. could not be interpreted in terms of the intramolecular shielding effect. In this case, therefore, whether the CH protons are shielded from the solvent or not, seems to be a dominant factor for the origin of the “doublet peak”. The magnetic anisotropy effect of a peptide group was also examined.
1H and 13C NMR studies on N‐acetyl‐L‐alanyl‐L‐alanine‐methylamide
Authors: Asakura Tetsuo 
Published: April 2003

Abstract1H and 13C NMR spectra of N‐acetyl‐L‐alanyl‐L‐alaninemethylamide and N‐acetyl‐L‐alanyl‐L‐alanine methyl ester were measured in [2H]6‐dimethyl sulfoxide and deuteriochloroform/trifluoroacetic acid solutions. The assignments of the N‐terminal and internal NH proton peaks of the amide could be made by means of deuterium exchange experiments in [2H]6‐dimethyl sulfoxide solution. An association model of the amide with an antiparallel β‐sheet structure was proposed by taking into account the presence of an IR absorption at 1 690 cm−1 as amide I band and the results of the measurement of 3JHN‐CαH coupling constants, as well as the deuterium exchange experiment. Moreover, the interaction between the peptide units in these two compounds and trifluoroacetic acid seems to be weaker than the N‐acetyl‐L‐alaninemethylamide‐acid interaction in a deuteriochloroform/trifluoroacetic acid solvent system of the same concentration.
Gas permeability of the racemic form of poly(γ‐benzyl glutamate)
Authors: Vivatpanachart Somsak , Tsujita Yoshiharu , Takizawa Akira 
Published: April 2003

AbstractSorption of carbon dioxide gas by a film of the racemic form of poly(γ‐benzyl glutamate) was observed over the temperature range from 10 to 40°C and the permeability coefficient of carbon dioxide gas through the film was measured over the temperature range from 30 to 120°C. Different sorption isotherms were obtained in the ranges above and below the glass‐like transition temperature, respectively. The result indicates that the sorption behavior is influenced by the side chain mobility. The amount of sorption by the racemic form of poly(γ‐benzyl glutamate) does not vary with the intermolecular benzene ring stacking, but is similar to that of the form C of poly(γ‐benzyl‐L‐glutamate) which contains no stacking. The breakdown of the intermolecular benzene ring stacking, which was confirmed by X‐ray diffraction analysis and differential scanning calorimetry, results in an abrupt increase of the permeability and the diffusion coefficients, and conversely the formation of the stacking leads to an abrupt decrease in the permeability and the diffusion coefficients. Below the transition temperature, the permeability coefficient of the racemic form of poly(γ‐benzyl glutamate) is smaller than that of the forms A, B, and C of poly(γ‐benzyl‐L‐glutamate), related to the benzene ring stacking. The diffusion coefficient was estimated from the free volume theory, and the calculated value was compared with the value obtained from the permeability and the solubility coefficients. The fractional free volume was estimated to be about 0,068, when the best fit between the experimental and the calculated diffusion coefficients was obtained by a trial and error method.
Versuche zur umsetzung von methylendiphenolen mit glucosederivaten und zur kondensation von O‐phenylglucosidderivaten
Authors: Kämmerer Hermann , Ritz Jürgen 
Published: April 2003

AbstractAttempts to apply known methods of glucosidation to oligo[(hydroxyphenylene)methylene]s were not satisfying. The reaction of 4,4'‐dimethyl‐2,2'‐methylenediphenol (1a) with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranosyl bromide gave a monoglucoside in 11% yield. A second attempt, the condensation of suitable O‐phenylglucoside derivatives was unsuccessful. From a series of O‐phenylglucosides (4) only 4‐(2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranosyloxy)benzylbromide could be condensed with O‐(4‐hydroxymethylphenyl)‐2,3,4,6‐tetra‐O‐acetylglucopyranose to the corresponding diglucoside of 4,4'‐oxydimethylenediphenol (7). Condensation reactions of the O‐phenylglucoside 4k, to obtain an O‐glucosidized poly[(hydroxyphenylene)methylene], were accompanied by decomposition. The results showed that the usual methods of the preparation of glucosidized phenols cannot be transferred to oligomeric or polymeric derivatives.
Interaction of human serum proteins with synthetic polymers in heterogeneous system
Authors: Ohno Hiroyuki , Nii Atsushi , Abe Koji , Tsuchida Eishun 
Published: April 2003

AbstractThe interactions of human serum proteins with synthetic macromolecules were studied in heterogeneous solution systems. An alternating copolymer of styrene with maleic anhydride was crosslinked by diamines with different number of methylene groups varying from 2 to 10, and the degree of crosslinking (mole fraction of amide linked units) was changed from 7 to 43% in order to elucidate the effects of pore size, density of ionic site, and flexibility of the macromolecules. The adsorption of serum proteins on the resins was studied with human serum albumin and γ‐globulin as typical proteins in human serum. The resins were dispersed in phosphate buffer solutions, and these were mixed with the phosphate buffer solutions of albumin and/or γ‐globulin. After a suitable period of incubation at 20°C, the mixed solutions were centrifuged. The degree of protein‐adsorption was determined from the remaining amounts of proteins in the supernatant as measured by U.V. spectrometry. It was observed that the adsorption of albumin was influenced by the subtle balance of hydrophobicity and hydrophilicity of the resin. On the other hand, γ‐globulin was adsorbed not only by the hydrophobic resin but also by the hydrophilic (ionic) resin. The resin which was crosslinked to 16% by hexamethylenediamine showed high affinity towards γ‐globulin at pH 7,4. Selective adsorption was also possible: Almost all of the γ‐globulin and only little of the albumin were adsorbed within half an hour at 20°C by the use of this resin.
Refractive indices and refractive index increments of liquid systems at elevated pressures, 1. Design of an instrument and refractive index of trans‐decalin as function of temperature and pressure
Authors: Hammel G. L. , Schulz G. V. , Lechner M. D. 
Published: April 2003

AbstractA new interferometer has been designed in order to perform measurements of refractive indices and refractive index increments on liquid systems under elevated pressure at different temperatures. The method of measurement, the calibration of the instrument and the treatment of data are described. With a series of test measurements on trans‐decalin it is shown that with this instrument reliable results are obtained.
Refractive indices and refractive index increments of liquid systems at elevated pressures, 2. Refractive index increment of the system polystyrene/trans‐decalin as function of temperature and pressure
Authors: Hammel G. L. , Schulz G. V. , Lechner M. D. 
Published: April 2003

AbstractRefractive indices and refractive index increments of the system polystyrene/trans‐decalin were measured under pressures up to 500 bar and at temperatures between 20 and 60°C. The measurements were performed with a new, recently designed interferometer. The results demonstrate a sufficient agreement of the refractive index values measured at different temperatures and pressures with the equations of Eykman and Gladstone‐Dale whereas the Lorenz‐Lorentz equation indicates larger deviations. The experimental data of the refractive index increment follow none of the refractive index mixture rules. It is therefore recommended to determine refractive index increments at different pressures experimentally.
Preparation and homopolymerization of 2‐arylazo‐5‐dimethylaminobenzyl acrylates and methacrylates
Authors: Lokaj J. , Pivcová H. , Hrabák F. 
Published: April 2003

Abstract2‐Arylazo‐5‐dimethylaminobenzyl alcohols (1) were prepared and used for the preparation of 2‐arylazo‐5‐dimethylaminobenzyl acrylates (2) and methacrylates (3); these compounds were characterized by melting points, IR and 1H NMR spectra. The coloured compounds 2 and 3 were subjected to radical homopolymerization in solution initiated with AIBN at 70°C, and [η], IR and 1H NMR spectra of the polymers were determined. Alternatively, the coloured polymer with 2‐(2‐chlorophenylazo)‐5‐dimethylaminobenzyl methacrylate monomeric units was prepared by coupling of the copolymer of 3‐dimethylaminobenzyl methacrylate and styrene with 1‐chlorobenzenediazonium chloride.
Polymer incompatibility study of a polystyrene network contaminated by linear polyisoprene chains
Authors: Rietsch François , Dambrine Françoise , Morcellet Joëlle 
Published: April 2003

AbstractThe present paper deals with the study of anionic polystyrene (PS) networks containing linear polyisoprene (PI) chains. Special attention was devoted to the problem of the compatibility of such a system, depending on the molecular weight M̄w (weight average) or M̄n (number average) of the chains in the polymeric network and the number average molecular weight M̄n of the linear polyisoprene chains. For that purpose, three different methods were used: diffusion of a concentrated linear polyisoprene solution into the polymeric network, “in situ” polymerization of isoprene inside the polystyrene network, and crosslinking of “living” polystyrene in a linear polyisoprene solution.
Dielectric behaviour of poly(sulfonyl‐1‐butylethylene) in concentrated solutions
Authors: Araki Kazuo , Aoki Harumi , Imamura Yoshio 
Published: April 2003

AbstractMeasurements of the dielectric relaxation of three poly(sulfonyl‐1‐butylethylene)s, (PSB), of different molecular weights were carried out in benzene solutions of polymer contents from 3,0 to 50,0 wt.‐%. It was found that the distribution parameter of the dielectric relaxation time was constant above a critical polymer contents and the activation energy increased with polymer contents. The observed relaxation time was analyzed by Fröhlich's theory assuming limiting relaxation times. The lower limit in the relaxation time, τ1, was independent of polymer contents above the critical polymer contents, in contrast to the upper limit relaxation time, τ2, which depended on polymer contents. The polymer contents dependence of the critical frequency below and above the critical polymer contents was interpreted by the free volume effect. The unperturbed molecular dimension at the critical polymer contents was also discussed.
Flexibilität und hydrodynamische eigenschaften von polymethylmethacrylat in binären mischlösungsmitteln
Authors: Wunderlich Winfried 
Published: April 2003

AbstractLight scattering and viscosity measurements of poly(methyl methacrylate) have been carried out, in order to investigate the correlation of unperturbed dimensions and intrinsic viscosity of the polymer relative to the thermodynamic properties of solvent mixtures as compared to results obtained in single component solvents. The unperturbed dimensions of the polymer turned out to be unaffected by the mixed solvent, whereas a strong dependence of the hydrodynamic radius on the enthalpy of mixing of the two solvent components was observed. Hence unequivocal conclusions about the chain structure of the dissolved polymer cannot be drawn from hydrodynamic measurements in mixed solvents. If values of the viscosity constant K0 in these systems in the vicinity of the Θ‐point are extrapolated according to the Burchard‐Stockmayer‐Fixman equation, they do not agree with data measured at T = Θ.
Mechanism of radiation‐ and photo‐induced polymerizations of styrene elucidated by the stereoregularity of the polymers
Authors: Matsuzaki Kei , Ichijo Chikara , Kanai Taiichi 
Published: April 2003

AbstractThe stereoregularity of polystyrenes (PS's) obtained by γ‐ray and UV light irradiation was determined by 13C NMR spectroscopy, and the mechanism of polymerization was discussed. PS's obtained by 60Co γ‐ray irradiation in bulk, methylene chloride and carbon tetrachloride at 0°C showed bimodal molecular weight distributions. The stereoregularity expressed by the fraction of racemic dyads in the high molecular weight portions and the low molecular weight ones separated by thin layer chromatography (TLC) was 66 – 67% and 71%, respectively. The results indicate that the former portions are formed by a cationic mechanism and the latter by a radical mechanism. It was also confirmed that the polymerization by UV light irradiation with pyromellitic dianhydride (1,2:4,5‐benzenetetracarboxylic dianhydride) as an electron acceptor propagates by a cationic mechanism in polar solvents and by a radical mechanism in the bulk.
Linear oligopeptides, 70. Study of the relationship between conformation and nature of the side chain: Homologous series derived from α‐amino acid residues with linear hydrocarbon side chains
Authors: Toniolo Claudio , Bonora Gian Maria , Crisma Marco , Bertanzon Francesco , Stevens Eugene S. 
Published: April 2003

AbstractA series of N‐ and C‐protected L‐α‐aminobutyric acid homo‐oligopeptides from dipeptide through heptapeptide was synthesized by the dicyclohexylcarbodiimide and acyl azide coupling methods. The monodisperse peptides were characterized and found to be chemically and optically pure. By means of infrared absorption and circular dichroism in the vacuum ultraviolet (150 nm) the occurrence of the intermolecular β‐conformation in the higher oligopeptides in the solid state was ascertained. In solvents of low polarity at high dilution the amount of intramolecularly hydrogen‐bonded folded structure formation was established as a function of peptide chain length. Unordered and intermolecular β‐structures were found in alcohols and in water/2,2,2‐trifluoroethanol mixtures. The results obtained are compared with those already published of other homologous peptide series derived from L‐α‐amino acid residues with linear hydrocarbon side chains, namely alanine, norvaline, and norleucine. Analogies and differences with the series from β‐ and γ‐branched residues are also discussed.
The influence of molecular interaction on polymerization, 6. GPC study of polymethacrylates obtained in different solvents
Authors: Boudevska Hrissanta , Brutchkov Christo , Platchkova Svetla , Pascault Jean‐Pierre 
Published: April 2003

AbstractPoly(2‐naphthyl methacrylate)s (P‐2‐NM), poly(benzyl methacrylate)s (PBzMA) and poly‐(methyl methacrylate)s (PMMA) obtained by radical polymerization initiated with 2,2′‐azo‐isobutyronitrile (AIBN) in benzene, acetone and acetonitrile were investigated by means of gel permeation chromatography (GPC). The GPC curves of the polymethacrylates containing aromatic rings show lower molecular weights and higher polydispersities than those of PMMA. The polymerization in benzene leads to polymers with higher molecular weights and higher polydispersities than that in acetonitrile. Acetonitrile causes a formation of polymethacrylates with lowest molecular weight distribution. In comparison with the other solvents acetone gives PMMA with lowest molecular weight. Inversely, P‐2‐NM and PBzMA prepared in acetone are of highest molecular weights. The molecular weight and molecular weight distribution of PMMA is less sensitive to the change of the solvent than those of aromatic methacrylates.The GPC curves indicate similar dependence on the change of the polymerization medium for the copolymers of 2‐naphthyl methacrylate (2‐NM) with methyl methacrylate (MMA), and of benzyl methacrylate (BzMA) with maleic anhydride (MA) prepared in benzene, carbon tetrachloride, chloroform and acetonitrile.The results are explained assuming various termination and transfer reactions in different solvents. Some correlations established between the GPC curves and the association and dissociation of the monomer molecules in dependence of the dielectric constant of the solvent, previously observed by 1H NMR, are also discussed.
Polymorphic behaviour of poly[oxyoctanedioyloxy‐1,4‐phenylene‐(1‐methylvinylene)‐1,4‐phenylene] and poly[oxydecanedioyloxy‐1,4‐phenylene‐(1‐methylvinylene)‐1,4‐phenylene]
Authors: Roviello Antonio , Sirigu Augusto 
Published: April 2003

AbstractThe polymorphic behaviour of polymers

(n = 8, 10) has been investigated. They show thermotropic, mesophasic properties with a nematic structure. Both polymers exhibit a multiple solid state polymorphism which is a function of the temperature and of their thermal history.
Study on polymer solutions in solvent mixtures in the vicinity of the critical point of the solvents, 3. Turbidimetric study of four new ternary systems
Authors: Staikos George , Skondras Panayotis , Dondos Anastasios 
Published: April 2003

AbstractTurbidimetric results obtained with the ternary systems N,N‐dimethylformamide/cyclohexane/polystyrene, N,N‐dimethylformamide/cyclohexane/polybutadiene, methanol/cyclohexane/polystyrene, methanol/cyclohexane/poly(ethylene glycol) are reported. These results show that a very small quantity of polymer changes drastically the demixing curve of the two partially mixed liquids. The displacement of the heterogeneous region starts from the domain of the critical point of the two liquids and becomes more significant in the domain of compositions of the two liquids rich in the poor solvent of the polymer. A qualitative explanation of this phenomenon is attempted based on the theory of the isorange lines of two partially miscible liquids.
Redox polymerization, 7. Kinetics of the polymerization of acrylic acid derivatives initiated by the systems cyanoacetic acid/Mn(OCOCH3)3 and ethyl acetoacetate/Mn(OCOCH3)3 in glacial acetic acid
Authors: Haragopal Mahadevan , Jayakrishnan Athipettah , Mahadevan Venkatanarayana 
Published: April 2003

AbstractThe kinetics of polymerization of acrylamide, acrylonitrile and methyl methacrylate by the systems cyanoacetic acid/Mn(OCOCH3)3 as well as ethyl acetoacetate/Mn(OCOCH3)3 were investigated in glacial acetic acid medium in the temperature range of 25–45°C. Oxidation proceeds through intermediate complex formation between reactants. Competitive complexation of the substrates by Mn(II) leads to retadation of the rates by added manganous ions. Primary radicals from the substrate account for the initiation when acrylamide is used as the monomer, but with acrylonitrile and methyl methacrylate secondary radicals formed by the interaction of the 1:1 complex with monomers account for initiation. In presence of the monomers the retardation due to added manganous ions is absent. Termination in all cases is of the mutual type. Rate and equilibrium constants were evaluated.
Preparation of living mono‐ and dicationically growing polyacetals and attempts to prepare block copolymers thereof
Authors: Chwiałkowska Wiesława , Kubisa Przemysław , Penczek Stanisław 
Published: April 2003

AbstractMono‐ and dicationically living poly(1,3‐dioxolane) (pdxn) and poly (1,3‐dioxepane) (pdxp) were obtained with CF3SO3H (trifilic acid‐tfac) and (CF3SO2)2O (triflic anhydride‐tfan), respectively. Concentration of the active species and living character of polymers were established by applying the ion‐trapping technique. Addition of a second cyclic acetal to the living bifunctional polyacetal (e. g. addition of dxn to pdxp) leads to the formation of a block copolymer (according to 13C NMR), but before the second monomer polymerizes completely, the transacetalization process leads to the conversion of the internal homoblock to a more or less (depending on time) statictical copolymer. Thus, competition of the homopropagation and transacetalization is not in favor of formation of the block copolymers with pure homoblocks, at least when the second block, built on the already existing homoblock, is formed slower than the homoblock is reshuffled by transacetalization.
Étude de la stabilité à la lumière du poly(chlorure de vinyle) chloré
Authors: Decker Christian , Balandier Michel 
Published: April 2003

AbstractThe light‐stability of chlorinated poly(vinyl chloride) (PVCC) is investigated and the quantum yields of the major process involved are determined. By UV exposure, PVCC undergoes a fast dehydrochlorination process which develops ten times more efficiently than with poly(vinyl chloride) (PVC), leading to long chlorinated polyene sequences which are responsible for the rapid coloration of the irradiated polymer. Chain scission and crosslinking occur simultaneously, both in the presence and in the absence of oxygen, indicating that UV radiations are able to cleave the polymer chains. By reaction with polyenyl radicals, oxygen reduces slightly the efficiency of the dehydrochlorination, while promoting at the same time the formation of carbonyl and hydroperoxide groups in the polymer chain. The reasons of the high instability of PVCC against UV light are discussed and an overall reaction scheme is suggested to account for the various processes observed and their relative efficiencies.
Synthesis of polyamides containing cytosine and hypoxanthine
Authors: Muraki Michiro , Miura Yozo , Kinoshita Masayoshi 
Published: April 2003

AbstractThe di(cyanomethyl) methylsuccinate derivative of cytosine and di(p‐nitrophenyl) methyl‐succinate derivative of hypoxanthine were prepared and polycondensed with a variety of diamines to provide powdery polyamides with molecular weights in the range of 1000–3100. The polyamides are soluble in DMSO and formic acid, but insoluble in ordinary organic solvents.