bluuebunny/crossref_metadata_2025_split huggingface dataset:
High electric field birefringence and association modes of poly‐γ‐benzyl‐L‐glutamate solutions
Authors: Pyżuk Wiesław , Krupkowski Teodor 
Published: April 2003

AbstractThe Kerr constants of poly‐γ‐benzyl‐L‐glutamate, (poly[imino‐1‐(2‐benzyloxycarbonylethyl)‐2‐oxoethylene]), (PBLG), solutions in several solvents were measured as functions of the molecular weight of PBLG and electric field intensity. The results were interpreted in terms of association modes of PBLG.
The persistence of birefringence of polyethylene above its melting temperature
Authors: Czornyj George , Wunderlich Bernhard 
Published: April 2003

AbstractIt has long been known that polyethylene shish‐kebob crystals show birefringence which can persist up to 150°C or higher, while the equilibrium melting temperature is 141,4°C. Birefringence in macromolecules may be due to crystallinity or to orientation in the amorphous state. By carrying out parallel birefringence and heat of fusion measurements it is shown that polyethylene shish‐kebob crystals are metastable and have a zero entropy production melting temperature of 134–135°C. Their melting region is shifted to higher temperature due to effects of orientation in the amorphous portions of partially crystallized molecules.
Copolymerization of N‐vinyl‐ε‐caprolactam with maleic anhydride
Authors: Boghină Constantin 
Published: April 2003

AbstractThe copolymerization of N‐vinyl‐ε‐caprolactam (VCL) with maleic anhydride (MA) in homogeneous solution of N,N‐dimethylformamide at 70°C, initiated by benzoyl peroxide, is studied. VCL and MA form a 1:1 charge‐transfer complex which is confirmed by spectroscopic analysis. The complex is decisive in the copolymerization reaction and has an equilibrium constant of 0,2 l/mol. The reactivity ratios of the VCL‐MA pair are determined as follows:
Die Wärmekapazität von vollständig kristallinen Copolymeren des Polyoxymethylens
Authors: Dröscher Michael 
Published: April 2003

AbstractThe molar heat capacity of fully crystalline copolymers of trioxane and 1,3‐dioxolane can be discribed by the equation Cp(x2, T) = 36,75 + 0,1425 (t2 − 25) + 80 x2 in the temperature range 25°C < t < 140°C and at mole fraction of oxyethylene units x2 < 0,16. For x2 < 0,1 the molar heat capacity depends linearly on the reduced temperature T/Tm(x2), but is independent from counit content.
Polymere 3‐acryloyloxyalkyl‐ und 3‐acryloyloxyaryl‐4‐thiazolidone als strahlenschutzsubstanzen
Authors: Montoya Rolando , Schmidt Eckhard , Soto Jorge , Lüderwald Ingo 
Published: April 2003

AbstractThe syntheses of 3‐acryloyloxyalkyl‐ and 3‐acryloyloxyaryl‐2‐phenyl‐4‐thiazolidones (3a–c) from the corresponding hydroxyl derivatives 2a–c and acrylic acid chloride are described. These monomers were homopolymerized and copolymerized with N‐vinyl‐2‐pyrrolidone by radical initiation. The resulting water soluble copolymers were tested in animals for radioprotective activity and prolongation of efficiency.
Réactions primaires de dégradation oxydante au cours de l'autoxydation du poly(oxytétraméthylène) à 25°C, 3 Cinétique de la production des coupures statistiques et caractérisation de la réaction bimoléculaire non terminante des radicaux peroxyles secondaires
Authors: Thomassin Claude , Marchal Jean 
Published: April 2003

AbstractThe kinetics of the production of random chain scissions by oxidative degradation of poly(oxytetramethylene) was determined during the radiation‐induced autoxidation of solutions of the polymer in chloroform at 25°C. Ethylene oxide resulting from autoxidation of ethylene produced by unimolecular decomposition of alkoxy‐1 alkylperoxy radicals partly inhibits the chain scission. This property allowed the characterization of the existence of a second primary mechanism of oxidative degradation of the polymer as non‐terminating bimolecular reaction of these peroxy radicals followed by a ß‐scission of the produced alkoxy radicals.
Nebenreaktionen der radikalisch ausgelösten cyclisierung von 2,2′‐methylen‐bis(4‐methyl‐1,2‐phenylen)‐dimethacrylat
Authors: Kämmerer Hermann , Pachta Jiri 
Published: April 2003

Abstract2,2′‐Methylene‐bis(4‐methyl‐1,2‐phenylene) dimethacrylate (1) was reacted with an excess of 2,2′‐azoiso‐butyronitrile (mole ratio 1:15) highly diluted in boiling benzene. The reaction products were separated by column chromatography. It was found that the 1‐cyano‐1‐methylethyl radical induced the cyclization of 1 to yield the product of a head to tail addition (2) in 55% yield. In addition, the product of a head to head addition (3) was isolated in 4% yield. 35% of 1 reacted in the same way as it has already been observed as suppression of polymerization in the case of p‐tolyl methacrylate to give the products 4 and 5. The structures of the products were confirmed by elemental analyses, by IR‐UV‐, 1H NMR‐ and mass‐spectra as well as by the determination of their relative molecular masses and by quantitative hydrogenations.
Polymer modification and synthesis using sulfenyl derivatives, 5. Adducts with cis‐1,4‐polybutadiene
Authors: Brydon Albert , Cameron G. Gordon , Muir Robert B. 
Published: April 2003

Abstractcis‐1,4‐Polybutadiene (PBD) was reacted with a number of sulfenyl derivatives to produce adducts of varying degrees of saturation. The glass transition temperature (Tg) of the modified polymer increases with extent of reaction with p‐toluenesulfenyl chloride (1c) and 2‐nitrobenzenesulfenyl benzoate (2a). DSC traces indicate a “blocky” structure in adducts of 1c but not of 2a. The tensile strengths at break of the adducts of 1c show a progressive increase with increasing degree of saturation.
Osmotic coefficients of aqueous polyelectrolyte solutions at low concentrations, 4. Modified cylindrical cell model and its application
Authors: Oman Srečko , Bratko Dušan 
Published: April 2003

AbstractA modified rodlike model of linear polyelectrolytes is described and the calculated osmotic coefficients are presented as a function of the degree of polymerization of polyions. A comparision with experimental data is included and rather good agreement with theory is found at concentrations above 5.10−3 basemol/l. The concentration dependence of the properties of diluted polyelectrolyte solutions is discussed.
Photoconductivities of poly[γ‐(β‐N‐carbazolylethyl)‐L‐glutamate] and its charge‐transfer complex with 2,4,7‐trinitrofluorenone
Authors: Tanikawa Kiyoshi , Okuno Zenjiro , Iwaoka Takehiko , Hatano Masahiro 
Published: April 2003

AbstractPoly[γ‐(β‐N‐carbazolylethyl)‐L‐glutamate] (PCLG) was prepared by polymerizing the monomer which was synthesized by adapting the NCA method to a reaction product between L‐glutamic acid and N‐(β‐hydroxyethyl)carbazole. PCLG films were prepared on a quartz Nesa (In2O3) plate by casting technique. The charge‐transfer complex could be successfully formed only near the surface of the PCLG film by immersing the PCLG film into either a benzene or a methyl ethyl ketone solution of 2,4,7‐trinitrofluorenone (TNF), since both benzene and methyl ethyl ketone were poor solvents for PCLG and suitable solvents for TNF. A photocell was formed by depositing a translucent gold electrode with vaccum evaporation onto the immersed film. For a small content of TNF in both the immersed films and the homogeneously mixed films of PCLG with TNF, the photocurrent of PCLG was successfully sensitized by TNF, but the sensitized photocurrents retained the relation I>I in a similar way as the photocurrent of PCLG alone, where I was the photocurrent under illumination onto the positive Au electrode and vice versa. On the other hand, as the TNF content increased, I became remarkably greater than I. The PCLG polymer, therefore, can behave as a p‐type photoconductor, while the well‐doped PCLG‐TNF complex can behave as an n‐type photoconductor.
Sequence distribution of 1,4‐polybutadienes
Authors: Tanaka Yasuyuki , Sato Hisaya , Hatada Koichi , Terawaki Yoshio , Okuda Hiroshi 
Published: April 2003

AbstractThe spin‐decoupled 1H NMR and 13C NMR methods were presented for the determination of the cis‐trans sequence distribution in polybutadiene. Poly(butadiene‐2,3‐d2) and cis‐trans isomerized polybutadienes were used for the peak assignment and the resonance of methylene protons in cis‐trans linkage could be described as an A2B2 system. The dyad and triad sequence distributions of cis‐1,4 and trans‐1,4 units were determined for isomerized, equibinary and lithium catalyzed polybutadienes, and polycyclooctadienes. The accuracy of the measurements was also studied comparing the results with those by infrared method.
Simultaneous anodic and cathodic polymerizations of acrylamide
Authors: Bhadani Suraj N. , Prasad Yugal K. 
Published: April 2003

AbstractThe electrolysis of acrylamide in sodium nitrate/N,N‐dimethylformamide solutions leads to polymer formations simultaneously in the anode and cathode compartments. The influences of monomer concentrations, current levels, nature of some electrode metals and supporting electrolytes on polymerization were examined. Anodic polymers of high molecular weights were obtained (ca. 105). The current‐voltage curves and other experimental findings strongly suggest that the direct reduction of acrylamide at the cathode leads to the cathodic polymerization which is like the polymerization by anionic initiators in which the monomer gives a polymer of amide structure via a hydrogen transfer process. On the other hand, the anodic polymerization is possibly initiated by the species produced by the anodic reaction of the supporting electrolyte and is analogous to the free‐radical polymerization of acrylamide. Infrared spectra of the polymers show that the cathodic polymer is a polyamide \documentclass{article}\pagestyle{empty}\begin{document}$ \left( { \ldots \hbox{---} {\rm CH}_{\rm 2} \hbox{---} {\rm CH}_{\rm 2} \hbox{---} {\rm CO}\hbox{---} {\rm NH}\hbox{---} \ldots } \right) $\end{document} whereas the anodic has a CC chain structure \documentclass{article}\pagestyle{empty}\begin{document}$ \left( { \ldots \hbox{---} {\rm CH}_{\rm 2} \hbox{---} {\rm CH}\left( {{\rm CONH}_{\rm 2} } \right)\hbox{---} \ldots } \right) $\end{document}.
Thermal resistance of crosslinked and substituted poly(phenylene sulfide)s
Authors: Hortling Bo 
Published: April 2003

AbstractCrosslinked and substituted poly(phenylene sulfide)s, prepared by reacting p‐chlorosubstituted benzenes with sulfur, were investigated by TG in air. Using the difference method and an assumed first‐order calculation, the reaction order, activation energy and frequency factor were determined. The pyrolyses were carried out under nitrogen and in the presence of 5% oxygen. The IR spectra and the sulfur contents of the polymers and pyrolysis products were determined. The highest activation energies were found for unsubstituted polymers. Linear poly(phenylene sulfide) has the best thermal stability, but also the other polymers show rather good stabilities up to 400–500°C. The IR spectra and sulfur‐contents of the pyrolysis products suggest stable, condensed, and sulfur containing aromatic intermediates formed during the degradations. The obtained polymers can be manufactured over large temperature ranges by common techniques.
Kettenübertragung durch tetrabromkohlenstoff bei der polymerisation von styrol und von vinylacetat
Authors: Gleixner Günther , Breitenbach Johann Wolfgang , Olaj Oskar Friedrich 
Published: April 2003

AbstractThe constant of chain transfer to carbon tetrabromide in the polymerization of styrene has been redetermined by directly measuring the consumption of the chain transfer agent using a GC‐technique and simultaneously evaluating the conversion of monomer to polymer. Values of 250 (at 60°C) and 185 (at 95°C) have been obtained by this method. These values agree in order of magnitude with those recently obtained by Thomson and Walters from the determination of polymer molecular weights and, accordingly, exceed the values previously reported by approximately two powers of ten. An analysis of the limiting viscosity numbers of the polymers prepared in presence of carbon tetrabromide shows an excellent agreement with these new high values of the chain transfer constant of carbon tetrabromide. For the constant of chain transfer to carbon tetrabromide in the polymerization of vinyl acetate a value of 6·103 has been obtained at 60°C, which again is two to three orders of magnitude higher than those values given previously.
Photochimie de la polyacrylophénone en solution, 1. Cinétique de transfert d'énergie triplet‐triplet
Authors: Salvin Roger , Meybeck Jean , Faure Jean 
Published: April 2003

AbstractThe kinetics of triplet‐triplet energy transfer is studied in fluid solution with polyacrylophenone, (poly(1‐benzoylethylene)), (PAP) as the energy donor and 1‐methylnaphthalene (MeN) as quencher. The rate constant of quenching Kq is obtained from the Stern‐Volmer constant Kqτ for the inhibition of main chain scission in PAP, the lifetime τ of the excited state being measured by picosecond laser photolysis. Kq does not verify the scheme of a diffusion controlled reaction generally applied for small molecule as valerophenone. We proposed a kinetic scheme based on the Voltz theory of energy migration where a migration term Ω of the excitation energy in PAP adds to the material diffusion of MeN. The good agreement obtained for the value of Ω determined by extrapolation at infinite viscosity of solvent, where the material diffusion is negligible, supports our hypothesis of energy migration in PAP at room temperature.
Étude de la solvatation préférentielle des poly(méthacrylates de méthyle) dans quelques mélanges de solvants
Authors: Katime Issa , Strazielle Claude 
Published: April 2003

AbstractThe behavior of some poly(methyl methacrylate)s in solvent‐mixtures (benzene‐methanol, carbone tetrachloride‐methanol and dioxane‐methanol) was investigated. The dependence of microstructure and molecular weight of the polymer on the preferential solvation was determined. The existence of a conformational transition for syndiotactic poly(methyl methacrylate) in dioxane and in dioxane‐methanol could be shown.
Notes on the determination of unperturbed dimensions of stiff chain polymers by hydrodynamic methods
Authors: Kovář Josef , Fortelný Ivan , Bohdanecký Miloslav 
Published: April 2003

AbstractAn analysis was carried out of the possibilities provided by the Yamakawa‐Fujii theory of the hydrodynamic properties of polymer solutions for the determination of the structure parameters (especially of unperturbed dimensions) of polymers with stiff chains. Conditions for using the plots M/[η] vs. M1/2 and M/[f] vs. M1/2 for the given purpose were defined. The occurrence of a minimum in the former plot observed for ladder polymers was explained. The confrontation of the results of the analysis with hydrodynamic data for polychlorophenylsilasesquioxane and polyphenylsilasesquioxane indicate a branched structure of these ladder polymers.
1H NMR and2D NMR relaxation and wide line measurements in partially deuterated polystyrenes
Authors: Willenberg Bernd , Sillescu Hans 
Published: April 2003

AbstractSolutions of chain‐ (PS‐d3) and phenyl ring (PS‐d5) deuterated polystyrenes in perdeuterated PS‐d8have been investigated with1H and2D NMR relaxation and wide line methods. The intra‐ and intermolecular parts of the1H second moments at −100°C are 3,7 G2and 2,0 G2, respectively, for PS‐d3, and 14,7 G2and ca. 0 G2, respectively, for PS‐d5. The intermolecular contribution to the1H spin lattice relaxation rate, determined at 55 MHz between 150°C and 250°C, is about one third of the total rate in PS‐d3, and negligible in PS‐d5. We suggest that this contribution is caused by rotational fluctuations of the intermolecular H ⃛H vectors. The intramolecular1H‐ and2D‐relaxation rates indicate that the phenyl group motion is somewhat faster than the rotational segmental motion of the polymer chain.
Solution properties of poly(butyl methacrylate‐co‐acrylonitrile)
Authors: Arulsamy S. M. , Santappa M. 
Published: April 2003

AbstractPoly(buty1 methacrylate‐co‐acrylonitrile) of 1 : 1 molar composition has been prepared by bulk polymerization process using 2,2′ ‐azoisobutyronitrile (AIBN) as the initiator and fractionated using ethyl methyl ketone and methanol as the solvent and the precipitant respectively. The identical value of the refractive index increments (dn/dc) of these fractions indicated their homogeneity in chemical composition. The dilute solution properties of these fractions in N,N‐dimethylformamide (DMF), ethyl methyl ketone (MEK), and acetone have been investigated employing light‐scattering, osmometry and viscometry techniques. The following Mark‐Houwink relationships have been established at 25°C:

The unperturbed dimensions for the copolymer have been evaluated and compared with those for the constituting homopolymers. A solvent dependence of the unperturbed dimension has been observed. The steric factor, σ, was found to be 2,64 in DMF and 2,48 in MEK for poly(buty1 methacrylate‐co‐acrylonitrile) compared to a value of 2,20 for poly(acrylonitri1e) in DMF, and 2,09 for poly(buty1 methacrylate) in MEK which suggests the greater stiffness of the copolymeric chain compared to the constituting homopol ymers.
Chelatbildung von 5‐methyl‐5‐hexen‐2,4‐dion/styrol‐copolymeren in lösung und an metallischen oberflächen
Authors: Brito Heide , Brito Victor , Springer Jürgen 
Published: April 2003

AbstractThe preparation and characterization (analyses of IR and mass spectra) of 5‐methyl‐5‐hexen‐2,4‐dione (1) and its polymerization and copolymerization with styrene are described. Poly(1) and copolymers from 1 and styrene give metal chelates in solution and on metal surfaces. Copolymers of 1 and styrene increase the adhesion and the resistance against corrosion of varnishes for metals on the basis of melamine.
1,3‐Bis(1‐phenylvinyl)benzene and its reactions with electron transfer reagents
Authors: Schulz Günther G. H. , Höcker Hartwig 
Published: April 2003

AbstractThe investigation of electron transfer and subsequent reactions of divinylidene compounds not capable of anionic homopolymerization was extended to 1,3‐bis(1‐phenylvinyl)benzene (2). A new method for the preparation of this compound is described. Its reaction with Li, Na, and K as electron transfer reagents in THF as solvent results in an increasing yield in polymeric combination products of the radical anions formed primarily with increasing reducing power of the alkali metal.The main product, however, in any case is the cyclic dimeric tetra‐anion of 2, which upon protonation yields 1,4,11,14‐tetraphenyl[4.4]metacyclophane (3).
The electro‐initiated cationic polymerization of indene, 2. Kinetics of polymerization
Authors: Bhadani Suraj N. , Baranwal Panchdeo P. 
Published: April 2003

AbstractThe electrolytically initiated anodic polymerization of indene in the solutions of tetraethylammonium hexachloroantimonate and tetrabutylammonium perchlorate in nitrobenzene under constant electric current and constant potential electrolysis conditions was studied. The polymerization was followed either under continuous electrolysis or by addition of the monomer to the pre‐electrolysed solution of the salt. The monomer consumption follows the first‐order rate‐law, log[M]0/[M]t=kt, and the rate constant of the polymerization increases with increasing current level. The polymer formation was greatly affected by the change of the dielectric constant of the medium, the anode material, and the nature of the supporting electrolyte. The mode of initiation process depends upon the type of the salt. Mechanisms for the initiation reaction were elucidated.
Koagulation unlöslicher, gefällter polymermoleküle, grundlagen der trübungstitration
Authors: Hoffmann Martin , Urban Heinrich 
Published: April 2003

AbstractAfter the precipìtation of polymer from a solution of concentrationcthe light scattering intensityR0(in the direction of the primary beam) usually does not reach a constant value but is equal tokc2t,tbeing the time since precipitation. The constantkdoes not depend on molecular weightM(104<M<106) and is proportional to 1/η1, η1being the viscosity of the dispersing medium. Various polymers with refractive index incrementsvihave nearly the same value ofk/v. Furthermore long chain branching or intramolecular crosslinks do not influence this value. These results prove that the coagulation of polymers is controlled by diffusion (theory of coagulation bySmoluchowski).Coagulation and coalescence are retarded if the polymer molecules are able to associate or to crystallise. They stop at low particle weights if the particles are hard or if they carry about 10 electric elementary charges per particle.During turbidimetric titrations freshly precipitated molecules are quickly adsorbed by the existing particles, thus increasing mainly the number average particle weight. If this increase in turbidity is small compared to that resulting from the coagulation of particles, the increase ofR0·V/V0with logVis proportional to the square of the concentration of all the precipitated molecules during titrations of chemically equal molecules. (Vis the volume of the titrated solution.) From titration curves one may thus derive the distributions of solubilities and molecular weights. Similar evaluations give the distribution of chemical compositions, if polymers with nearly equal molecular weights are titrated (GPC‐eluates).
Thermal decomposition of γ‐ray irradiated poly(vinylidene fluoride) and the copolymer of vinylidene difluoride with vinyl fluoride
Authors: Hagiwara Miyuki , Ellinghorst Guido , Hummel Dieter O. 
Published: April 2003

AbstractThe thermal decomposition of γ‐irradiated poly(vinylidene flouride) and the copolymer of vinylidene difluoride and vinyl fluoride has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and mass spectral analysis of the evolved gas. Under non‐isothermal conditions (heating rate = 2 K min−1), polymers were found to lose their weight in two stages. The main process of the weight loss was the splitting‐off of HF. Various aromatic compounds containing F were also observed to evolve, although their contribution to the total weight loss was small. For the volatilization reaction occurring at high temperature, initiation through random chain scission was suggested. Kinetical analysis of TG traces for the volatilization showed that the apparent overall activation energy decreases with increasing dose.
Studies on chitin, 4. Evidence for formation of block and random copolymers of N‐acetyl‐D‐glucosamine and D‐glucosamine by hetero‐ and homogeneous hydrolyses
Authors: Kurita Keisuke , Sannan Takanori , Iwakura Yoshio 
Published: April 2003

AbstractChitin was deacetylated by heterogeneous and homogeneous alkaline hydrolyses. In the heterogeneous hydrolysis, upper limits in the degree of deacetylation were found to exist at low reaction temperatures. The products obtained were all insoluble in water and those with a degree of deacetylation up to 80% retained some crystallinity. These results seemed to indicate that the deacetylation under the heterogeneous conditions proceeded preferentially in the amorphous region to give block‐type copolymers of N‐acetyle‐D‐glucosamine and D‐glucosamine units. In the homogeneous hydrolysis, on the other hand, all the products with a degree of deacetylation of ca. 50% were found to be soluble in water independent of the hydrolysis temperature. The crystallinity of the products decreased much more rapidly and samples with a degree of deacetylation >40% were amorphous. These results suggested that the deacetylation under homogeneous conditions proceeded randomly to give the random‐type copolymers of the two units. This randomness was concluded to have brought about the interesting water‐solubility of products with a degree of deacetylation of ca. 50%.