bluuebunny/crossref_metadata_2025_split huggingface dataset:
Le poly(α‐acétoxystyrène) et les copolymères de l'α‐acétoxystyrène avec le styrène et styrènes substitués obtenus par polymérisation thermique. Etude de la microstructure et de la stabilité thermique des polymères
Authors: Montheard Jean‐Pierre , Camps Marcel , Kawaye Saadallah , Pham Quang Tho , Seytre Gérard 
Published: April 2003

AbstractThe microstructure of poly(α‐acetoxystyrene), prepared from α‐acetoxystyrene by bulk thermal polymerization, was studied by 1H and 13C NMR spectroscopy. Anomalies observed in the NMR spectra could be ascribed to fragmentations with formation of benzoxy and acetoxy radicals followed by re‐initiation. The thermal degradation of the polymer, resulting in the formation of polyphenylacetylene, rules out certain types of transfer. α‐Acetoxystyrene was copolymerized with styrene or substituted styrenes and the NMR study (1H and 13C) was limited to α‐acetoxystyrene. The composition of the copolymer could be ascertained by means of the resonances of the quaternary carbons of the aromatic cycle. The copolymers were characterized by viscometry, GPC, and thermal degradation. Their compositions, except that of poly(α‐acetoxystyrene‐co‐styrene) were determined by elemental analysis.
Electric dipole moment of cellulose‐ and amylose derivatives
Authors: Araki Kazuo , Imamura Yoshio 
Published: April 2003

AbstractThe electric dipole moments (per repeating unit) of cellulose acetate and tricarbanilate, and amylose acetate and tricarbanilate were determined in 1,4‐dioxane solution at 30°C. The parallel component of the moment to the chain contour was also estimated for samples of various molecular weights, and they were almost independent on molecular weight, indicating no excluded volume effect on the dipole moment. The persistence dipole moment, and monomer dipole component along the chain contour for cellulose derivatives were about 50% smaller than those for amylose derivatives. The relation between the dipole moment and the chain dimension is discussed for cellulose‐ and amylose derivatives.
Polymere charge‐transfer‐komplexe auf der basis von polyvinylalkoholacetalen, 5
Authors: GeißLer Ulrich , Schulz Rolf C. 
Published: April 2003

AbstractBy reaction of poly[2‐(1‐naphthyl)‐1,3‐dioxan‐4,6‐diylmethylene] (3), poly[2‐(2‐naphthyl)‐1,3‐dioxan‐4,6‐diylmethylene] (5), poly[2‐(9‐isobutyl‐3‐carbazolyl)‐1,3‐dioxan‐4,6‐diylmethylene] (7) and poly[2‐((S)‐9‐(2‐methylbutyl)‐3‐carbazolyl)‐1,3‐dioxan‐4,6‐diylmethylene] (9) with 3,5‐dinitrobenzoylchloride (12) or 4,5,7‐trinitro‐9‐fluorenone‐2‐carboxylic acid chloride (2) polymeric intramolecular charge‐transfer‐complexes (4a, 4b, 6, 8a, 8b, and 10) were synthesized. The polymers were investigated by means of UV or remission spectroscopy as well as by differential thermal analysis.
Determination of the orientation distribution function of amorphous polymers by wide angle X‐ray scattering measurements
Authors: Biangardi Harald J. 
Published: April 2003

AbstractA new method based on the inversion of a relation derived by Krathy, and thereby allowing the determination of the orientation distribution function of amorphous polymers by Wide Angle X‐Ray Scattering (WAXS), is described. With a simple approximation, in many cases disturbing intramolecular scattering can be separated from the measured azimuthal intensity distribution along the first maximum of the amorphous halo. For oriented amorphous poly(ethylene terephthalate), the 2nd and 4th moments of the determined orientation distribution functions agree very well with those from birefringence and spectroscopic measurements. The method is not applicable to partially crystalling polymers, because the approximation for intramolecular scattering does no longer hold. Finally, the intrinsic birefringence of bisphenol‐A‐polycarbonate was determined by this method to be 0,236 ± 0,004.
Cyclization dynamics of polymers, 5. The effects of solvent on end‐to‐end cyclization of poly(ethylene oxide) probed by intramolecular pyrene excimer formation
Authors: Cheung Seung‐Tong , Winnik Mitchell A. , Redpath Anthony E. C. 
Published: April 2003

AbstractIntramolecular excimer formation between pyrenes attached to the ends of a poly(ethyleneoxide) sample of nominal molecular weight 9600 has been examined in twelve solvents. In ten non‐protic solvents the excimer to pyrene locally excited fluorescene intensity ratio IE/IM is inversely proportional to solvent viscosity, as expected for a diffusion‐controlled process. Similar results were obtained for 〈k1〉 values obtained from flash‐photolysis studies, where 〈k1〉 is the average rate constant for end‐to‐end cyclization in the polymer. In water and methanol, the extent of excimer emission and the rate of intramolecular excimer emission and the rate of intramolecular excimer formation were substantially greater than one would infer on the basis of solvent viscosity alone.
New organic polymers, 4. Synthesis and characterization of polymers containing 3,3′‐dioxo‐5,5′‐biindol‐2,2′‐diyl units
Authors: Suthar Bhikhu P. 
Published: April 2003

AbstractPolymers containing 3,3′‐dioxo‐5,5′‐biindol‐2,2′‐diyl units were synthesized by high temperature polycondensation of 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid (1) with ethylene dichloride and dibromide, 4‐chloromethylbenzyl chloride and bromide, 4‐chloromethyl‐2,5‐dimethylbenzyl chloride and bis(4‐chloromethylphenyl) ether under different experimental conditions. These resulting polymers 5a–d were characterized by viscometric and IR Spectral studies and by TG in air. Kinetic parameters of their thermal degradation were evaluated.
Copolymerization of C‐vinyltriazoles and C‐vinyltetrazole with vinyl monomers
Authors: Wouters G. , Smets G. 
Published: April 2003

AbstractThe copolymerizations of 4(5)‐vinyl‐1,2,3‐triazole, 1‐p‐bromophenyl‐4‐vinyl‐1,2,3‐triazole and 2‐methyl‐5‐vinyltetrazole with styrene, methyl methacrylate and vinyl acetate have been examined and the corresponding copolymerization parameters r1, r2 were evaluated. The reactivities Q of these monomers are lower than that of styrene contrarily to other C‐vinylheterocyclic monomers; it is assumed that it results from a limited stabilization of the corresponding radicals. In the case of 4(5)‐vinyl‐1,2,3‐triazole, copolymerizations carried out at different temperatures and varied monomer concentrations show that intermolecular monomer association (as evidenced by NMR and IR measurements) does neither affect the copolymer composition nor the internal monomer triad structure of the copolymer.
Induced optical activity in copolymers of (—)‐p‐(3‐menthyl) acrylate with 4‐vinylpyridine
Authors: Majumdar Ramendra Nath , Carlini Carlo , Bertucci Carlo 
Published: April 2003

AbstractThe present paper reports on the synthesis of copolymers of (—)‐p‐(3‐menthyl) acrylate (1) with 4‐vinylpyridine (2) by radical polymerization in a large range of composition. Reactivity ratio values of the two comonomers, evaluated by the Kelen‐Tüdös method, have allowed to show that 2 exhibits a rather high reactivity as compared with 1. The average sequence length of the co‐units and their distribution in the macromolecules were evaluated. The chiroptical properties of side chain pyridine chromophores were investigated by circular dichroism measurements and related to composition and distribution of the monomeric units.
Adiabatic polymerization of ϵ‐caprolactam in presence of lithium chloride, 3. Oligomer formation
Authors: Biagini Emilio , Pedemonte Bruno , Pedemonte Enrico , Russo Saverio , Turturro Antonio 
Published: April 2003

AbstractThe activated anionic polymerization of ϵ‐caprolactam is strongly affected by LiCl addition to the polymerizing medium. Large variations in the yield of the polymerization products are induced by increasing salt content: both high polymer and cyclic dimer yields sharply decrease as functions of the salt concentration, whereas monomer and (in part) higher oligomers show a relevant increase. Also the production of low molecular weight side products is influenced by LiCl: higher salt concentrations induce the formation of larger amounts of side compounds. Monomer equilibrium data reveal that the salt negatively affects the thermodynamics of polymerization. ΔG variation as a function of LiCl content shows an increasingly relevant influence of the entropic contribution to the standard free energy change. The effects of LiCl on ring‐ring equilibria are qualitatively interpreted on the basis of both the strong ion‐ion interactions between Li+ ions and carbonyl groups and the interchain densification process.
Electrolytic conductivity of polyeiectrolyte solutions
Authors: Vink Hans 
Published: April 2003

AbstractThe electrolytic conductivity of the polyelectrolytes poly(methacrylic acid), carboxymethyl‐cellulose, poly(vinylsulfonates), and poly(styrenesulfonates) was investigated. The concentration dependence of the equivalent conductivity was studied in detail and the limiting equivalent conductivity Λ0 was determined. The rapid increase of the equivalent conductivity in dilute polyelectrolyte solutions, which is characteristic for most polyelectrolyte systems, was found to be due to decreased counterion binding in very dilute solutions. In this respect the behaviour of the poly(styrenesulfonate)s was exceptional, as their equivalent conductivities were practically constant down to limiting concentrations. Also, the poly(styrenesulfonic acid) clearly displayed specific hydrogen ion‐polyion interactions.
Synthèse et transformations chimiques des télomères de l'undécène‐10 oate de méthyle, 2. Synthèse de diols polyhalogénés
Authors: Battais Alain , Boutevin Bernard , Piétrasanta Yves , Sarraf Tarek El 
Published: April 2003

AbstractSeveral telomers of methyl 10‐undecenoate were prepared with different telogens and identified by IR and NMR spectroscopy or by GPC. Chemical transformations of these telomers led to new polyhalogenated acids of alcohols having high molecular weights.
Retardation effect of 1,1,4,4‐tetraphenyl‐2‐tetrazene in the radical polymerization of methyl methacrylate
Authors: Sugiyama Kazuo , Oda Tetsuo , Maeshima Toshihisa 
Published: April 2003

AbstractThe decomposition of 1,1,4,4‐tetraphenyl‐2‐tetrazene (TPT) was carried out in four aprotic solvents [acetonitrile, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and benezene]. ΔH≠ was found to decrease with increasing polarity of the solvent. The effect of TPT on the polymerization of methyl methacrylate (MMA) was also studied in the same solvents. TPT was found to be a retarder for the radical polymerization of MMA. The induction period is affected by the polarity of the medium. In addition, the chain‐transfer constant of TPT (CTPT) was calculated to be 5,40, 4,00, 2, 78, and 3, 96 for the polymerization of MMA in acetonitrile, DMSO, DMF, and benzene, respectively. The transition state of the chain‐transfer reaction seems to be influenced by the polarity of the solvent.
Concentration dependence of the dielectric behavior of poly(2‐methyl‐1‐pentene sulfone) in benzene solution
Authors: Araki Kazuo , Imamura Yoshio 
Published: April 2003

AbstractDielectric measurements over a wide frequency range (30 Hz to 3 MHz) were made on solutions of poly(2‐methyl‐1‐pentene sulfone) (PMPS) in benzene at various polymer mass fractions up to 40 wt.‐%. The dielectric relaxation time increased linearly with increasing polymer concentration. A breaking point in the plot of the relaxation time against the polymer concentration appeared at a critical polymer concentration. The dielectric behavior below and above the critical polymer concentration was interpreted on the basis of the theory of free volume effect. The observed dielectric relaxation time was analyzed by Fröhlich's theory, assuming two limiting relaxation times, τ1 and τ2. The lower limit, τ1, which corresponds to the segmental motion, was independent of the polymer concentration above the critical polymer concentration, but in contrast, the upper relaxation time corresponding to the motion of the molecule as a whole, τ2, depended strongly on the polymer concentration.
Quantitative analyse der selbstassoziation von hämoglobinmolekülen anhand der konzentrationsabhängigkeit der spektren
Authors: Burkhard Oswald , Barnikol Wolfgang K. R. 
Published: April 2003

AbstractThe dependence of the spectrum of oxygenated hemoglobin (Hb) on the Hb concentration was measured and it was found that Hb solutions do not obey Lambert‐Beer's law. The absorption coefficient depends clearly on the Hb concentration. As all external parameters were kept constant except Hb concentration, the only way to explain our result is to assume that Hb molecules undergo self association and that this self association is reflected in the behaviour of the absorption coefficient. To get parameters which are suited to describe the self association of Hb molecules, two models were used. The first model is based on the idea that Hb associates according to the following equation: Hb + Hb ⇌ (Hb)2. Hb represents a single Hb molecule (consisting of two α‐and two β‐chains) and (Hb)2 a complex of two Hb molecules. The second, more complicated model, takes into account higher associates of Hb molecules (like (Hb)3, (Hb)4, . . .). By using a least square fitting, it was possible to match experimental data and theoretical curves. Furthermore it became evident that at Hb concentrations, which are of physiological relevance, about 90% of the Hb molecules are involved in self association. The second model revealed that at those Hb concentrations there is a considerable portion of complexes which are composed of 10 or more Hb molecules.
Propylene polymerization on titanium‐magnesium catalysts determination of the number of active centers and propagation rate constants
Authors: Bukatov Gennadii D. , Shepelev Sergei H. , Zakharov Vladimir A. , Sergeev Sergei A. , Yermakov Yurii I. 
Published: April 2003

AbstractBy use of the quenching technique with 14CO and 14CO2 the number of active centers and the propagation rate constants (kp) were determined for the propylene polymerization on different titanium‐magnesium catalysts in the presence and absence of an organoaluminium cocatalyst. The kp values at 70°C were found to be 500–1000 1·mol−1·s−1, which were confirmed by independent data of molecular mass measurements of the isotatic polymer after a short polymerization time (5 s). Similar isotactic and atactic kpvalues were found. The maximum number of active centers for supported titanium‐magnesium catalysts can reach about 10% of the titanium content in the catalyst. The kp values of ethylene polymerization on catalysts active without an organoaluminium cocatalyst were also determined (≈ 104 l·mol−1·s−1 at 70°C).
Determination of unsaturated end groups in low molecular weight poly(vinyl chloride) by 1H NMR spectroscopy of the hydroxyphenyl substituted product
Authors: Bǎrboiu Virgil , Robilǎ Gabriela , Buruianǎ Emil , Caraculacu Adrian 
Published: April 2003

AbstractPoly(vinyl chloride) of low molecular weight (the fraction extracted with a hexane/acetone mixture (vol.‐ratio 3:2)) was substituted by hydroxyphenyl groups and then analyzed by 1H NMR spectroscopy. It was established that the 1H NMR spectra of hydroxyphenyl substituted poly(vinyl chloride) prepared by removal of HCl, allows to determine the number of unsaturated end groups and to distinguish between the structures CHClCH2CHCHCH2Cl and CH2CHClCHCHCH2Cl, and even between their trans and cis forms. In addition the 1H NMR spectra of hydroxyphenyl substituted poly(vinyl chloride) prepared without removal of HCl allow to determine the total number of unsaturated end groups.
Über polyarylenalkenylene und polyheteroarylenaklenylene, 12. Synthesen und charakterisierung von poly(thieno[2,3‐b]thiophen‐2,5‐diylvinylenarylenvinylen)en, poly(thieno[3,2‐b]thiophen‐2,5‐diylvinylenarylenvinylen)en und einigen modellverbindungen
Authors: Koßmehl Gerhard , Beimling Peter , Manacke George 
Published: April 2003

AbstractFrom Wittig‐reactions of thieno[2,3‐b]thiophene‐2,5‐dicarboxaldehyde (1) and thieno‐[3,2‐b]thiophene‐2,5‐carboxaldehyde (4) with “mono‐and bis Wittig‐salts” of the benzene and thiophene series two series of isomeric poly(thienothiophene‐2,5‐diylvinylenearylenevinylene)s 3a—c and 5a—c, and some model compounds 7a—c and 8a—c were obtained. Wittig‐reacaldehyde (11) with “mono‐and bis‐Wittig‐salts” gave two series more of model compounds 10a—c, 12a—c, 13a, c, 14a, c. The structure of all compounds were confirmed by elemental analyses, IR, and electronic spectra, and those of the model compounds additionally by mass spectra, and in case of sufficient solubility by 1 H NMR spectra. The electrical conductivities of all compounds and the thermooxidative degradation of the polymers were investigated.
Characterization of furfuryl alcohol oligomers by 1H and 13C NMR spectroscopy
Authors: Fawcett Allan Herbert , Dadamba Wilfred 
Published: April 2003

AbstractThe characterisation of the oligomers of furfuryl alcohol was performed using 13C NMR spectroscopy and high resolution 1H NMR spectroscopy. A shift parameter scheme for the 13C shifts of the furan ring was devised and utilised for the assignment of the shifts of the oligomers. An analysis of the chemical composition of several furfuryl alcohol resings produced with different catalysts was performed with the aid of the assignments.
Study of step‐growth polymerizations using epoxy‐carboxy reaction, 1. Study of the epoxy‐carboxy reaction on models in solvents of low or medium dielectric constants
Authors: Madec Pierre‐Jean , Maréchal Ernest 
Published: April 2003

AbstractDue to its importance in the field of block‐polycondensation and of chemical modification, we carried out an extensive study of the epoxy‐carboxy reaction on models. This papier is related to the reaction of benzoic acid with 1‐phenoxy‐2,3‐epoxypropane in the presence of a basic catalyst, N,N‐dimethyldodecylamine. It is carried out in low polar solvents (xylene, chlorobenzene, and o‐dichlorobenzene); essential kinetic parameters are reported. From studies carried out under stoichiometric or non‐stoichiometric conditions a general rate equation (υ = k [acid]0.5 [epoxy] [amine]) is obtained. Kinetic relations are the same, no matter what the catalyst is: dimethyldodecylammonium benzoate or free amine. From these kinetic data it results that the overall mechanism involves two steps.
Study of step‐growth polymerizations using epoxy‐carboxy reaction, 3. General analysis of the results obtained on models in various solvents
Authors: Madec Pierre‐Jean , Maréchal Ernest 
Published: April 2003

AbstractA global analysis of the kinetic results relating to a model reaction of epoxy‐carboxy polycondensation is reported. The model is the reaction of benzoic acid with 1‐phenoxy‐2,3‐epoxypropane carried out in the presence of N,N‐dimethyldodecylamine as catalyst. The hypothesis concerning the contribution of two competitive ractions as suggested in the two preceding parts of this series is subjected to a mathematical treatement. This allowed the determination of the rate constants of each reaction. All the kinetic characteristics obtained in a broad range of experimental conditions fit the reaction scheme, which is described in detail. Exceptions are found for borderline cases. The rate constants of the reaction of the classical dependence on dielectric constant and temperature. Activation parameters of each reaction are reported.
Kinetics of polymerization of alkyl cyanoacrylates by tertiary amines and phosphines
Authors: Pepper David Charles , Ryan Bernard 
Published: April 2003

AbstractA theory of the overall rates and molecular weights in slowly‐initiated, non‐terminated polymerizations is developed for cases of complex initiation of alkyl cyanoacrylates by tertiary amines. Results with butyl cyanoacrylate (BCA) in the solvent THF, and five different amines (chiefly pyridine and derivatives) show widely differing overall rates. The theory, with the aid of previously determined initiation rate constants, permits the same value for the propagation rate constant (kp) to be derived in all cases, corroborated by values derived from the simpler overall kinetics of polymerisation initiated by Ph3P. The rate constant kp shows very slight temperature dependence, less than one order of magnitude between 20 and −80°C.
Glass transition and melting temperatures of random copolyesters of poly(ethylene terephthalate) with p‐hydroxybenzoic acid, 3
Authors: Balachandar M. , Balakrishnan T. , Kothandaraman H. 
Published: April 2003

AbstractThe glass transition temperature of the random copolyesters of poly(ethylene terephthalate) and p‐hydroxybenzoic acid prepared by molten state polycondensation increases with increasing concentration of p‐oxybenzoate units (oxy‐1,4‐phenylenecarbonyl units). The observed values of the glass transition temperature are compared with the values predicted from various empirical equations on the Tg's of copolymers and the concave Tg composition curve is explained in terms of the internal stiffening effect of the p‐oxybenzoate unit. The melting temperatures of the copolyesters vary with composition and show an eutectic phase diagram. The melting temperature and enthalpy of fusion of the homopolymer of p‐hydroxybenzoic acid were determined making use of Flory's equation on the melting point of a copolymer.
Reactions of macro‐ions resulting in the formation of block and graft copolymers. Grafting of polymers with aromatic groups
Authors: Kučera Miloslav , Salajka Zdeněk , Majerová Karla , Navrátil Milan 
Published: April 2003

AbstractGrafting of poly(oxytetramethylene) (polytetrahydrofuran) chains containing living oxonium end groups onto polymers containing aromatic rings was investigated. The rate of grafting was found to be slow, but under favourable conditions several moles of polytetrahydrofuran can be grafted to one mole of polystryrene. Macrocations may also be grafted to the surface of in‐soluble polymers dispersed in a solution of grafting ions. This was proved by grafting living polytetrahydrofuran onto poly(phenylene oxide) or random poly(1‐butene‐co‐styrene). Macro‐cations can be prepared from an anionic living polymer via transformation of the growing centers. Thus, poly(dimethylsiloxane), whose original anionic centers were transformated into cationic ones, was grafted to polystyrene. Exchange reactions were found to take place in the living system on polytetrahydrofuran or poly(dimethylsiloxane) grafts, thus influencing their length. The graft copolymers are strong surfactants. Separation from their mixture with homo‐polymers by a repeated extraction of homopolymers with a solvent is difficult and sometimes impossible.
Molmassenverteilung und lösungszustand von linearen polyethylenen, 2. Vergleich von berechneten mit experimentell bestimmten streufunktionen
Authors: Böhm L. L. , Lanver U. , Lechner M. D. , Hertel P. 
Published: April 2003

AbstractScattering functions for linear polyethylenes were calculated, using different assumptions, and compared with experimentally determined scattering functions of the system polyethylene/decane. It is pointed out, that the polyethylene macromolecules in a good solvent can be treated as statistical coils with a non‐uniform expansion and a constant average expansion exponent ε and not as statistical coils with uniform expansion. Comparison of the experimentally determined and the calculated scattering functions yields a molar mass distribution of polyethylene which is in agreement with the results from GPC‐measurements within the limits of experimental error.