bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymer reactions, 8. Oxidative pyrolysis of poly(propylene)
Authors: Chien James C. W. , Kiang Joseph K. Y.
Published: April 2003

Poly(propylene) has been oxidized at temperatures between 240 and 289°C. The products were GC separated and on‐line identified by an interfaced GC peak identification system. The major products are CO2, H2O, acetaldehyde, acetone, butanal, formaldehyde, methanol and other ketones and aldehydes. Most of the products can be accounted for by well‐known reactions of alkoxyl and peroxyl radicals; the major products are derived from the secondary alkoxy and peroxy species. Oxygen starvation is manifested in diffusion limited products of olefins and dienes, and the increase of CO2 and H2O formation in pure oxygen atmosphere. The first order rate constant at 240°C is 2,4·10−3 S−1 with an overall activation energy of ca. 16 kcal·mol−1 (67 kJ·mol−1). If one assumes the oxidative pyrolysis to share the same reaction pathways as autoxidation at lower temperatures, then the observed rate constants and activation energy may be calculated from kinetic parameters measured earlier for autoxidation of poly(propylene) from 71 to 140°C. Good agreement was obtained implying a similarity of oxidative degradation of the polymers spanning a large temperature range.
Spectroscopic characterization and chiroptical properties of the copolymers of (−)3‐menthyl acrylate and (−)3‐menthyl methacrylate with styrene
Authors: Majumdar Ramendra Nath , Carlini Carlo
Published: April 2003

Optically active copolymers of (−)3‐menthyl acrylate (MtA) and (−)3‐menthyl methacrylate (MtMA) with styrene (St) of different compositions were prepared by radical initiation. The reactivity ratios were determined by the least square evaluation of the Kelen‐Tüdös parameters. Substantially alternating copolymers by donor‐acceptor complex polymerization and the corresponding model compounds were also prepared. Spectroscopic and chiroptical properties of these copolymers and models were studied. The possible mechanisms of the generation of the induced dissymmetry of the longest wavelength π → π* electronic transition of the aromatic chromophore of St co‐units are discussed.
Functional metal‐porphyrazine derivatives and their polymers, 3. Catalytic activity of Fe(III)‐3,4,3′,4′,3″,4″,3″′,4″′‐octacarboxyphthalocyanine for decomposition of hydrogen peroxide
Authors: Shirai Hirofusa , Maruyama Akio , Takano Junji , Kobayashi Kesayoshi , Hojo Nobumasa , Urushido Kunio
Published: April 2003

The decomposition reaction of hydrogen peroxide was carried out by using Fe(III)‐3,4,3′,4′,3″,4″,3″′,4″′‐octacarboxyphthalocyanine (Fe(III)‐oaPc) as a catalyst, which has previously been reported by Boston et al. Fe(III)‐oaPc is a remarkably effective catalyst for the reaction, compared with hemin, other metal‐phthalocyanine compounds, or other iron complexes such as [Fe(III)‐(bipy)3]X3. The kinetics of this reaction was also investigated in the pH range 5,5 – 10,5 by measuring the initial velocity, V0, of the increasing concentration of O2 using a Warburg respirometer. The reaction proceeds according the catalase‐like mechanism. On the basis of the results of Sigel et al., the reaction mechanism is discussed.
Functional metal‐porphyrazine derivatives and their polymers, 4. Synthesis of poly(styrene) bonded Fe(III)‐ as well as Co(II)‐4,4′,4″,4″′‐tetracarboxyphthalocyanine and their catalase‐like activity
Authors: Shirai Hirofusa , Maruyama Akio , Kobayashi Kesayoshi , Hojo Nobumasa , Urushido Kunio
Published: April 2003

Metal‐4,4′,4″,4″′‐tetracarboxyphthalocyanine [Metal = Fe(III), Co(II), Mt‐taPc] were synthesized by the hydrolysis of metal‐4,4′,4″,4″′‐tetracarboxamidephthalocyanine (Mt‐tamPc). These metal‐taPc are soluble in water and in aprotic polar solvents such as N,N′‐dimethylformamide. Poly(styrene) bonded Mt‐taPc was synthesized by Friedel‐Crafts reaction of poly(styrene) with Mt‐taPc tetraacid chloride. The polymers contain about 4 mole‐% Mt‐Pc rings which are covalently bonded to poly(styrene). The decomposition reaction of hydrogen peroxide by catalysis with polystyrene containing Mt‐Pc rings was carried out in heterogeneous aqueous media at pH 7,0. The polymer catalysts show a catalase‐like activity. The activation energies with the polymer bonded Mt‐Pc were found to be about half of those with Mt‐taPc. From continuous flow experiments in a column, the polymer attached catalyst was found to be very stable, compared with free Mt‐taPc.
Studies of optical activity of poly(l‐menthyl vinyl ether)
Authors: Kurokawa Masahiro , Minoura Yuji
Published: April 2003

The optical activities of poly(l‐menthyl vinyl ether) (PMVE), obtained by cationic polymerization were studied. The polymerizations were carried out at various temperatures (−72 to +30°C), with different solvents and catalysts. The optical rotation of PMVE, which was polymerized with BF3O(C2H5)2 in toluene at −72°C, was found to be independent of the initial monomer concentration; but it depends on the activity of the catalyst. The absolute values of optical rotation of PMVE decreased with increasing temperature and dielectric constant of the solvent. The relationship between the optical activities of PMVE and the polymerization conditions is discussed.
Erweiterte Meßmöglichkeiten in der analytischen Ultrazentrifugation durch die Verwendung eines neuartigen Kollimators
Authors: Floßdorf Josef
Published: April 2003

The experience with a novel collimating system enhancing the intensity of rotor illumination by a factor of 46 as compared with conventional equipment, is reported. This system allows to work at wave lengths down to 220 nm and/or to afford higher optical densities also in the solvent sector.
Poly(ethylene terephthalate): A solid state condensation process, 2. Copolymerization
Authors: Dröscher Michael
Published: April 2003

Copolyesters of poly(ethylene terephthalate) containing 0,95 to 14,2 mole‐% di(oxyethylene)oxy units are prepared in a solid state condensation process. A low molecular weight prepolymer with reactive end groups is annealed at temperatures between 235 and 250°C. Samples with molecular weights from 2 000 to 26 000 are obtained. The melting behaviour of the copolyesters is determined by the crystallinity of the precondensate, the counit content, and the degree of polymerization.
Kinetics of nitrogen dioxide initiated polymerization of acrylamide
Authors: Bhadani Suraj N. , Prasad Yugal K.
Published: April 2003

The polymerization of acrylamide initiated by NO2 in DMF was investigated. The initial rate of the polymerization increases with the first power of the monomer concentration and a half power of the initiator concentration. The overall activation energy of the polymerization was determined to be about 20 kcal/mol (84 kJ/mol). The copolymerization of acrylamide was also carried out with MMA in a solution of NO2 in DMF. The copolymer was found to be enriched in MMA content. The polymerization appeared to be initiated by free radicals.
Dynamic mechanical behaviour of chlorinated polyethylene
Authors: Pereña José M. , Fatou José G. , Guzmán Julio
Published: April 2003

Dynamic mechanical measurements of chlorinated polyethylenes with chlorine contents ranging from 5,4 to 31 wt.‐% were carried out using a dynamic viscoelastometer. The complex modulus and loss factor were determined at four frequencies in the temperature range from −150°C to 100°C. Two relaxation processes (α and γ) were observed. The first one occurs at temperatures ranging from 21°C to 40°C, depending on the chlorine content; there is a minimum in the temperature of the α process at about 20 wt.‐% of chlorine. The activation energies for this α process are higher than 100 kcal/mol, and therefore this α relaxation is considered to be different from the α relaxation in linear polyethylene. On the other hand, the α relaxation of chlorinated polyethylenes is similar to that of the parent polyethylene, taking place at temperatures ranging from −137°C to −116°C (at 3,5 Hz). The activation energies for this α process range from 14 to 26 kcal/mol (1 kcal = 4,184 kJ).
Network disentanglement and time‐dependent flow behaviour of polymer melts
Authors: Wagner M. H. , Meissner J.
Published: April 2003

For small strains Lodge's rubberlike‐liquid theory is a valid description of the rheological behaviour of polymer melts, but at higher strains the theory fails: The phenomenon of shear thinning which is characteristic for the shear flow of nearly all polymer liquids is not explained, and in elongation the deviation of the experimental data from the predictions of Lodge's theory reflect also a flow thinning, and not a strain hardening in spite of the pronounced S‐shape of the stress‐strain diagrams. Comparing the measured stress growth and stress relaxation data with the predictions of the theory, it must be concluded that the temporary physical network structure of the polymer melt is destroyed increasingly with the magnitude of the deformation. Hence, the number of entanglements decreases with increasing strain. For simple shear and uniaxial extension of a well‐defined polyethylene melt the strain dependence of the relative entanglement density is discussed. The irreversibility of the disentanglement process of the network is considered.
Copolymerization of carbon dioxide with propylene oxide catalyzed by O‐methylated or crosslinked poly(p‐hydroxystyrene)/diethylzinc system
Authors: Tsuchida Eishun , Kasai Masanori
Published: April 2003

Effective catalysts for the copolymerization of CO2 with 1,2‐epoxypropane were prepared from partially O‐methylated or crosslinked poly[1‐(4‐hydroxyphenyl)ethylene] and Zn(C2H5)2. The highest activity was obtained with catalysts of 30 to 40% methylation or crosslinking. Inactivation of the catalysts during the copolymerization was decreased by crosslinking, increasing the yield of the copolymer. The higher rigidity of the catalyst structure is responsible for its higher activity and stability.
Kinetik der Wachstumsreaktionen der Copolymerisation von Butadien und Styrol mit Lithiumorganylen
Authors: Ohlinger Rainer , Bandermann Friedhelm
Published: April 2003

The rate constants of the propagation reactions of the lithiumalkyl catalyzed copolymerization of butadiene and styrene in toluene were measured and their rate constants and activation energies and the association constants of the initiators were determined. It turned out, that the cross reaction of styryllithium with butadiene is faster by a factor of 100 as hitherto assumed. The problems in determining rate constants from copolymerization reactivity ratios are discussed.
The photosensitized grafting of N‐vinyl‐2‐pyrrolidone on cotton using anthraquinone reactive dyes
Authors: Abdel‐Hay Fouad I. , Barker Paul , Guthrie James T.
Published: April 2003

The photosensitized grafting of N‐vinyl‐2‐pyrrolidone on cotton has been successfully carried out over a range of pH values, monomer concentrations and for various concentrations of dye‐sensitizer. Grafting is shown to be critically dependent on each of these factors. Evidence is presented which suggests that the dye is only physically held by the substrate which in turn indicates that grafting occurs via a hydrogen abstraction process. The physical nature of the graft copolymer (cellulose‐co‐N‐vinyl‐2‐pyrrolidone) is shown through electron micrographs. Reflectance spectroscopy provides an insight into the part played by the dye‐sensitizer in the grafting reaction.
Peroxodiphosphate‐ascorbic acid redox couple as an initiator for vinyl polymerization
Authors: Hariharan S. S. , Maruthamuthu Meenakshi
Published: April 2003

Primary radical termination is found to be significant in the P2O84− ‐ascorbic acid redoxinitiated polymerization of acrylonitrile in aqueous solution at low converstions. Degradative chain transfer involving the P2O84− ‐ascorbic acid complex is invoked to explain the monomer exponent of unity and the initiator exponent of zero at high conversions (>10%) of the monomer.
Copolymerization of 1,6‐anhydro‐sugar derivatives with cyclic monomers, 1. Tri‐O‐benzyl ether and tri‐O‐methyl ether of 1,6‐anhydro‐ß‐D‐glucopyranose as sugar monomers
Authors: Uryu Toshiyuki , Hatanaka Kenichi , Matsuzaki Kei
Published: April 2003

The cationic, ring‐opening copolymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐ß‐D‐glucopyranose with epichlorohydrin, 3,3‐bis(chloromethyl)oxetane and 1,3‐dioxolane was investigated with phosphorus pentafluoride as catalyst at low temperatures. Besides, copolymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐methyl‐ß‐D‐glucopyranose with epichlorohydrin was studied. Structure and composition of the copolymers were determined by 1H and 13C NMR spectroscopy, indicating that copolymerization occurred in each combination of monomers. Number‐average molecular weights of copolymers were in the range of 1 400 to 22 800. From the specific rotation and 13C NMR spectrum of copolymers, it was revealed that the ring‐opening copolymerization of the benzylated 1,6‐anhydro‐glucopyranose with the cyclic monomers occurred in a stereoregular manner to give the C‐1 carbon of glucose unit with α‐configuration. Debenzylation of a copolymer prepared from 1,6‐anhydro‐2,3,4‐tri‐Obenzyl‐ß‐D‐glucopyranose and 1,3‐dioxolane gave a copolymer composed of free sugar units in the polymer main chain. Assignment of 13C NMR spectra of 2,3,4‐tri‐O‐benzyl‐ß‐D‐glucopyranan and of a copolymer of 1,6‐anhydro‐2,3,4‐tri‐O‐benzyl‐ß‐ß‐glucopyranose with 1,3‐dioxolane was attempted.
Synthesis of new monomers having a secondary amino group by lithium alkylamide catalyzed addition reactions of primary amines with 1,4‐divinylbenzene
Authors: Maeda Mizuo , Nitadori Yoshiaki , Tsuruta Teiji
Published: April 2003

To establish appropriate reaction conditions for the synthesis of new monomers having a secondary amino group, a lithium alkylamide catalyzed addition reaction of primary amines with styrene was examined as the model reaction. The selectivity of N‐alkyl‐2‐phenethylamines (2) and the rate constant of the reaction were determined. On the basis of results of the model reaction, new styrene derivatives having a secondary amino group (5) were synthesized by lithium alkylamide catalyzed addition reactions of primary amines with 1,4‐divinylbenzene.
Festphasensynthese von oligonucleotiden, 11. Verwendung eines neuartigen hydrophilen perlpolymerisats als träger
Authors: Heidmann Walter , Köster Hubert
Published: April 2003

New hydrophilic swellable and lowly crosslinked bead copolymers consisting of dimethylaminocarbonylethylene or ‐propylene and alkoxycarbonylethylene or ‐propylene repeating units were prepared starting from activated esters of acrylic acid (8a–10a) or methacrylic esters (8b–10b) and N,N‐dimethylacrylamide (12a). This “hydrophylic Merrifield carriers” were applied for polymer‐supported oligodeoxynucleotide syntheses. They were found to be swellable in a wide range of solvents. The first deoxynucleoside was attached to the carrier via its 5′‐hydroxyl group by an ester bond. The cleavage of the bond between carrier and oligonucleotide was performed with aqueous sodium hydroxide under conditions which do not attack the N‐protecting groups attached to the oligonucleotide chain. The acid labile 1‐ethoxyethyl group was used as 3′‐protecting group for the phosphate component (N‐protected deoxynucleoside‐5′‐phosphate). Some suitable protected deoxynucleosides were synthesized for anchoring and deoxynucleoside‐5′‐phosphates for chain elongation. In a condensation reaction according to the diester method, a dinucleoside monophosphate (7) was prepared and, as a consequence of the flexibility of the polymeric backbone, the synthesis of longer oligonucleotides should be feasible. The alkali labile anchoring of the oligonucleotides to the carrier can allow to avoid wrong sequences by simple acylation of the non‐reacted 3′‐OH groups with acetic anhydride after each condensation step.
Festphasensynthese von oligonucleotiden, 12. Reaktionskinetische untersuchungen an einem quellbaren perlpolymerisat von acrylsäuremethylester
Authors: Heidmann Walter , Köster Hubert
Published: April 2003

The hydrolysis reaction of a swellable and lowly crosslinked bead polymer of methyl acrylate was studied. The linearity of the Arrhenius plot and the activation energy of 79,5 kJ/mol (19 kcal/mol) showed the reaction to be homogeneous. The activation energy of 46 kJ/mol (11 kcal/mol) for the liquid phase ester hydrolysis leads to a difference of 39,5 kJ/mol (8 kcal/mol) which is assumed to be the energy of diffusion. Hence, the swollen polymer behaves like a solvent of high viscosity, and the hydrolysis of the bead polymer of methyl acrylate is influenced in a complex manner by diffusion phenomena. Some of the carboxylate groups in the polymer could be activated with p‐toluenesulfonyl chloride and subsequently linked to the 5′‐OH of a 3′‐O‐protected deoxynucleoside. The minimum space of an ester group needed for being hydrolized by 0,2 M ethanolic sodium hydroxide was estimated to be 12 Å3, whereas the activated complex formed between the carboxylate group in the polymer and p‐toluenesulfonyl chloride needs about 51 Å3.
Analysis of small angle x‐ray scattering intensity of hard elastic polypropylene under extension
Authors: Shimizu Yoshio , Miyasaka Keizo , Ishikawa Kinzo
Published: April 2003

The influence of the changes in density and the extension distribution function on the profiles of the small angle X‐ray scattering of a hard elastic polypropylene film under extension was investigated. So far the scattering behavior of crystalline polymers, consisting of nearly parallel lamellae and intervening layers staked perpendicular to the fiber axis, has been described based on the lattice factor and the structure factor of a constant density difference. In this work it could be shown that the structure factor depends not only on the thickness, decided by the extension distribution function, but also on the density changing with the extension of each layer. Good agreement with the observation that the profile greatly changes in shape and intensity with extension could be obtained by introduction of an extension distribution function and a density function for the intervening layers.
Synthesis of polyamides containing 4,4′‐azodibenzamido units
Authors: Balasubramanian Mannarsamy , Nanjan Moola Joghee , Santappa Muchi
Published: April 2003

Four coloured polyamides containing azo‐p‐phenylene units were synthesised from 4,4′‐azodibenzoic acid and four aromatic diamines employing both interfacial and solution polymerization procedures. The polymers were characterized by their UV and IR spectra, by inherent viscosity measurements and by solubility data. The stability in conc. sulfuric acid and the thermal behaviour are discussed.
Structure and properties of segmented poly(ether ester)s and polyurethanes, 5. Synthesis of uniform oligo(oxytetramethylene)s
Authors: Bill Rudolf , Dröscher Michael , Wegner Gerhard
Published: April 2003

The synthesis of a series of homologous α‐hydro‐ω‐hydroxyoligo(oxytetramethylene)s, of the corresponding bis(phenylurethane)s, and of α‐hydro‐ω‐chlorooligo(oxytetramethylene)s is described. The purity of the individual oligomers was characterized by gel permeation chromatography and their melting behaviour was investigated. A value of 45 ± 2°C is derived as the equilibrium melting point of poly(oxytetramethylene) from a suitable extrapolation of the melting point of the oligomers to infinite molecular weight.
Polymerisationsauslösung mit substituierten ethanen, 2. Trennung der Oligomeren aus Methylmethacrylat und 1,1,2,2‐Tetraphenyl‐1,2‐diphenoxyethan
Authors: Błedzki Andrzej , Balard Henri , Braun Dietrich
Published: April 2003

The telechelics 1 from methyl methacrylate and 1,1,2,2‐tetraphenyl‐1,2‐diphenoxyethane, can be separated by adsorption chromatography. The structure of the dimers and trimers was identified by 1H NMR‐spectroscopy. The free radical oligomerization is a process in which the syndiotactic structure is favoured above the isotactic one.
Polymerization of epoxides catalysed by metalloporphine
Authors: Aida Takuzo , Mizuta Ryushin , Yoshida Yasuhiko , Inoue Shohei
Published: April 2003

The catalyst system obtained by the equimolar reaction of diethylaluminium chloride with α,β,γ,δ‐tetraphenylporphine exhibits high catalytic activity in the polymerization of propylene oxide to give a polymer with a narrow molecular weight distribution. Average molecular weight of the polymer can be controlled by the initial mole ratio of propylene oxide to catalyst or by the conversion. Ethylene oxide also produces a polymer having a narrow molecular weight distribution.
15N NMR spectroscopy, 27. Spectroscopic characterization of polyurethanes and related compounds
Authors: Kricheldorf Hans R. , Hull William E.
Published: April 2003

Natural abundance 15N and 13C NMR spectra of various polyurethanes were measured in trifluoroacetic acid. The polyurethanes were built up from aliphatic diols, polyesters of diols or oligoethylene glycols on the one hand, and from aliphatic α,ω‐diisocyanates or aromatic diisocyanates, on the other hand. In addition to the polyurethanes various low molecular weight model compounds, such as ureas, biurets, allophanic acid esters, uretdions and 1,3,5‐triazinetriones, were investigated. The substituent effects of phenyl groups in the above mentioned compounds were studied in various solvents. 15N NMR spectra were found to be more useful than 13C NMR spectra for the identification of the various isocyanate derivatives, while 13C NMR spectra have the advantage of a better signal‐to‐noise ratio.
Mass spectrometric characterization and thermal decomposition mechanism of some poly(organophosphazenes)
Authors: Ballistreri Alberto , Foti Salvatore , Montaudo Giorgio , Lora Silvano , Pezzin Giovanni
Published: April 2003

This work is concerned with the mass spectrometric characterization of polyaryloxy‐ and polyaminophosphazenes 1a–e. The mass spectral data show that the pyrolytic breakdown of poly(di‐β‐naphthoxyphosphazene) (1a) leads to the formation of cyclic oligomers. The poly(di‐arylaminophosphazenes) 1b–d decompose at low temperatures by a two‐stage process involving amine evolution. Finally, in the case of poly(dipiperidinophosphazene) (1e) the thermal decomposition leads to the complete destruction of the polymer backbone, with formation of ammonia and elemental phosphorus. The wide range of thermal decomposition pathways observed are peculiar of the phosphazene structure and represent a remarkable difference between this class of inorganic polymers and the organic ones.
Radiation graft polymerization of styrene to cellulose acetate‐butyrate
Authors: Odian George , Tsay Jiunn
Published: April 2003

The kinetics of radiation graft polymerization of styrene onto cellulose acetate‐butyrate is studied over a range of radiation intensities and monomer concentrations. The reaction is diffusion‐free under the experimental conditions as shown by the independence of the grafting rate on film thickness. The dependence of the grafting rate on monomer concentration increases from 3/2‐order to slightly greater than 5/2‐order with increasing radiation intensity. The dependence of the grafting rate on radiation intensity decreases from 1/2‐order to 0‐order with decreasing monomer concentration. Possible mechanisms for these results are discussed.
Oligomer‐oligomer incompatibility, 3. End‐group effects
Authors: Wolf B. A. , Schuch W.
Published: April 2003

In order to investigate the influences of different end‐groups on oligomer miscibility with other substances, oligo(propylene glycol)s bearing OH groups (OPG‐OH) studied in the previous paper2, were acetylated at both ends (OPG‐AC). The limits of miscibility of OPG‐AC with oligo(dimethylsiloxane) (ODMS) were measured turbidimetrically. A simple and reliable method for the determination of the critical points from turbidity data is presented. The observed upper critical temperatures (Tc) increase with degree of oligomerization of ODMS (ranging from 1 to 5), whereas Tc shows a minimum when the degree of oligomerization of the OPG‐AC is raised (from 1 to 57,5). For lower mol. wt. oligoglycols, the Tc‐values of ODMS/OPG‐AC are lower by ca. 50 K as compared with those of ODMS/OPG‐OH. The different end‐groups play a minor role with respect to the pressure influences (up to 1 500 bar the miscibility increases in all cases). For OPG‐AC the chain length of optimum miscibility with a given ODMS is found at considerably lower values than for OPG‐OH. The theoretical evaluation of the experimental material on the basis of the lattice theory yields a reduction in the enthalpies of mixing up to 10% and an increase in the volumes of mixing (<0) up to 50% when OH is replaced by AC. For the treatment of end‐group effects, the solubility parameter theory, when combined with the concept of molar attraction constants, presents several advantages: In particular it is possible to describe the phase separation behaviour of the different oligomer mixtures simply by means of solubility parameters and molar volumes of the different segments and end‐groups and to forecast the presence or absence of a chain‐length of optimum miscibility.
Craze formation in highly stretched polyurethane elastomers
Authors: Caspary Rudolf , Schnecko Hans W.
Published: April 2003

In a microscopy investigation it was found that stress‐whitening of polyurethane elastomers in the highly stretched state is created by a typical craze formation. Additional tests indicated that strain‐induced crystallinity is a first stage of crazing, possibly a necessary one. Density measurements suggested a microporous structure of the crazed matter. A fibrillar texture of the drawn material is indicated. Since craze formation is an energy absorbing mechanism, changes of important mechanical properties should be ascribed to this process.
Studies on formaldehyde resins, 18. Kinetics of acid‐catalyzed hydrolysis of bis(hydroxymethyl)melamine
Authors: Sato Kenji , Maruyama Kazuhiro
Published: April 2003

Kinetics and mechanism of the acid‐catalyzed hydrolysis of N,N′‐bis(hydroxymethyl)melamine [6‐amino‐2,4‐bis(hydroxymethylamino)‐1,3,5‐triazine] (M2F) were studied in the pH region of 0,5 − 7,6 at 30°C, where 30 vol.‐% DMSO aqueous solution was used as a solvent. The main results are as follows. The hydrolysis of M2F was of ca. 1,5th order in [M2F]0 at constant pH of 2,7 − 7,6, and was of ca. 1st order in the strongly acidic region of pH 0,5 − 1,0. Moreover, the hydrolysis rate of M2F attained a maximum at pH 4,0 corresponding to [HCl]0/[M2F]0 = 0,5 and a minimum at pH 1,9. On the basis of these results and kinetic investigations, the main reaction of the hydrolysis of M2F is plausible to be a reaction of the conjugate acid of M2F with a M2F molecule in the acidic range of pH > 2,7.
Polymères thiocarboxyliques, 1. Synthèse et étude de la polymérisation radicalaire de monomères dithiocarboxyliques
Authors: Haraoubia Rachid , Bonnans‐Plaisance Chantal , Levesque Guy
Published: April 2003

The syntheses and free‐radical polymerizations of methyl and carboxymethyl 4‐vinyldithiobenzoates are described as well as various copolymers. Copolymerisation parameters were determined for the copolymerizations of the methyl dithioester with styrene and with methyl methacrylate.
Polymere Brenzcatechin‐Derivate, 3. Darstellung und Eigenschaften von 3,4‐Methylendioxybenzyl‐methacrylat und seinen polymeren Derivaten
Authors: Iwabuchi Susumu , Nakahira Takayuki , Ikebukuro Yasuhiro , Takada Tadayoshi , Kojima Kuniharu
Published: April 2003

3,4‐Methylenedioxybenzyl methacrylate (3) was synthesized from 3,4‐methylenedioxybenzyl alcohol (2) and methacryloyl chloride. 3 was radically polymerized with tributylborane and copolymerized in cyclohexanone at room temperature under nitrogen. The following monomer reactivity ratios were determined M1 = 3: r1 = 0,68 and r2 = 0,40 for M2 = styrene, r1 = 0,78 and r2 = 0,16 for M2 = acrylonitril, and r1 = 0,28 and r2 = 1,47 for methyl methacrylate. Polymeric derivatives having 3,4‐dihydroxybenzyl units in the side chains were prepared from homo‐ and copolymers of 3. The thermal stability and redox behaviour of these polymers were investigated.
Lösungseigenschaften methyl‐ und chlorsubstituierter Bisphenol‐A‐Polycarbonate
Authors: Horbach Alfred , Müller Herbert , Bottenbruch Ludwig
Published: April 2003

Solution properties of dilute polymer solutions are studied for polycarbonates from 3,3′,5,5′‐tetramethylbisphenol A, from 3,3′‐dimethylbisphenol A, from 3,5‐dimethylbisphenol A, and from 3,3′,5,5′‐tetrachlorobisphenol A in regard to the influences of the different methyl and chloro substitutions. The Mark‐Houwink relationships are established in dichloromethane at 25°C. The unperturbed dimensions, evaluated from viscosity data using the Burchard‐Stockmayer‐Fixman method, are compared with those for bisphenol A polycarbonate. The unperturbed end‐to‐end distances are increased by the methyl and chloro substituents. The flexibility factors, calculated on the basis of the unperturbed dimensions and the dimensions of the freely rotating chain, indicate a greater rigidity of the polymer chain of the methyl and chloro substituted polycarbonates.
Investigation of poly(arylenevinylene)s, 24. High‐resolution solid‐state 13C NMR spectroscopy of poly(1,4‐phenylenevinylene)s
Authors: Schröter Bernd , Hörhold Hans‐Heinrich , Raabe Dietrich
Published: April 2003

High‐resolution 13C NMR spectra of solid poly(1,4‐phenylenevinylene), poly(1,4‐phenylene‐1,2‐diphenylvinylene) and of three related, substituted polymers (CN, OCH3, O) were obtained with a combined technique of heteronuclear decoupling, cross‐polarization and magic angle spinning. The reported chemical shifts were assigned by means of solid model compounds (trans‐stilbene, trans, trans‐1,4‐distyrylbenzene, tetraphenylethylene). Utilizing the high sensitivity of 13C NMR chemical shifts to chemical structure, this method is applied to structure confirmation, the determination of sp3‐defects in poly(phenylenevinylene)s PPV, and the determination of sterical and electronical effects of phenyl and phenylene groups.
Analysis of stress relaxation data for linear aromatic polyesters
Authors: Ng Tie Hwee , Leverne Williams H.
Published: April 2003

The stress relaxation of linear aromatic polyesters was measured at various temperatures for 1 h at a strain of less than about 0,7%. The polyesters of the terephthalate series had the highest relaxation moduli, E(t), when compared with the isophthalate and copolyester series of the same methylene sequence lengths at a fixed temperature and time. Within the individual series, the E(t) decreased with increasing methylene sequence length. Time‐temperature superposition was found to be applicable to the viscoelastic behaviours of only some of the semicrystalline polyesters under certain conditions. Subsequently, master curves for these polyesters were constructed. The data were studied by means of a generalized Maxwell model which fitted the corresponding master curves exactly. By the use of Andrews' second approximation, the relaxation time spectrum of these polyesters was obtained over a very wide time scale range. The resultant spectrum was fairly high and flat for the terephthalate and isophthalate series while that of the copolyester series resembled that of a typical amorphous polymer.
Über polyarylenalkenylene und polyheteroarylenalkenylene, 11. Synthesen von poly(1,4‐phenylenvinylen), poly(2,5‐thiophendiylvinylen) und poly(2,5‐furandiylvinylen) aus methylsubstituierten aldehyden
Authors: Koßmehl Gerhard , Yaridjanian Arshak
Published: April 2003

By means of the strong base sodium tert‐butoxide p‐tolylaldehyde (1a), 5‐methyl‐2‐thiophene carboxaldehyde (1b), and 5‐methyl‐2‐furancarboxaldehyde (1c) can be polycondensed in dimethylformamide to give poly(1,4‐phenylenevinylene) (2a), poly(2,5‐thiophenediylvinylene) (2b), and poly(2,5‐furandiylvinylene) (2c). 2a and 2b are also available from the Schiff's bases of 1a and 1b. The polymers are identical with polymers synthesized via the Wittig reaction. The vinylene units have the trans‐configuration.
Recherche de télomères à activité pharmacologique potentielle, 5. Réactions sur les télomères de l'acide acrylique
Authors: Bauduin G. , Bessière J.‐M. , Bondon D. , Martel J. , Piétrasanta Y.
Published: April 2003

Grafting of alcohols and amines on the telomers of acrylic acid was investigated. Carboxylic functions were activated via acid chlorides, anhydrides, or p‐nitrophenyl esters. Activation rates and grafting yields were determined in each case.
Studies on carboxymethylated cellulose: Potentiometric titrations, 2
Authors: Trivedi Harikrishna C. , Patel Chiman K. , Patel Raman D.
Published: April 2003

Effect of the sizes of counterions on the dissociation constant of carboxymethylated cellulose (CMC) is studied by potentiometry. Dissociation of protons from the CMC chains is suppressed with increasing size of the counterion. A good agreement is observed between the theory of Kagawa and Gregor and the experimental results accounting for the counterion size effect; a thermodynamic analysis of ΔpK supported this conclusion. Effects of concentration changes of the polyacid were also considered.
Characterization and morphology of thermoplastic interpenetrating polymer networks based on polystyrene and polystyrene‐polyisoprene three‐block copolymers
Authors: Widmaier Jean‐Michel , Hubert Jérôme , Meyer Guy
Published: April 2003

Semi‐interpenetrating polymer networks based on polystyrene and polystyrene‐polyisoprene three‐block copolymers (SIS) were prepared by anionic polymerization. Factors affecting synthesis, such as composition, molecular weight of either the unattached SIS or the polystyrene between crosslinks, elastomer content, have been varied. Their effect on network formation was examined by extraction experiments and swelling measurements. Their morphology was investigated by means of electron microscopy.
Konjugierte polymere mit azobenzol‐einheiten
Authors: Koßmehl Gerhard , Wallis Jan
Published: April 2003

By means of a Wittig condensation polymerization starting from 4,4′‐azodibenzaldehyde (1) and bifunctional Wittig salts of the benzene and thiophene series (2a–c) poly(azo‐1, 4‐pheny‐leneivnylenearylene)s (3a–c) were synthesized. Analogously the model compounds 6a–c, 8a–d, and 10a–c were prepared. The structures of the intensive red to brown polymers and the orange to red model compounds were proved by elemental analyses, IR‐ and electronic spectra, respectively mass spectral data for the model compounds. The thermooxidative degradation of the polymers and the electrical conductivity of the polymers and model compounds were studied.
Polymerisation von fulvenen, 4. Anionische polymerisation von 6,6‐dimethylfulven
Authors: Kronig Peter , Slongo Mario , Neuenschwander Markus
Published: April 2003

The reaction of 6,6‐dimethylfulvene (1) with small amounts of sodium cyclopentadienide (Na‐CPD) gives a mixture of oligomeric products, from which 1‐cyclopentadienyl‐1,3,3,‐trimethyltetrahydropentalene (7) was isolated with 67% yield. The structure of the main product 7 was proved by combination of spectrosopic methods as well as by NMR spectroscopy of its dianion. A reasonable reaction mechanism is presented and supported by isolation of other dimers 9 and 12 and trimers 10 as well as of side products 11 and 13. The product distribution is severely influenced by increasing the amount of Na‐CPD (favouring oligomers of type 11 and 13) as well as by addition of crown ether.
Stabilization of block copolymer micelles by UV and fast electron radiation
Authors: Tuzar Zdeněk , Bednář Bohumil , Koňák Čestmír , Kubín Miroslav , Svobodová Štěpánka , Procházka Karel
Published: April 2003

Micelles of a block copoymer poly(styrene/butadiene/styrene) with cores consisting of polybutadiene blocks were stabilized in dilute solutions by UV radiation in the presence of a photo‐initiator and also by fast electrons, and micelles of a block copolymer poly(styrene/ethene‐co‐1‐butene/styrene) with cores formed by the aliphatic blocks were stabilized by fast electrons, in dilute solutions. Stabilization of micelles, i. e., crosslinking of the chains in micellar cores as well as the properties of stabilized micelles were studied by conventional light scattering, by light scattering photon correlation spectroscopy and by gel permeation chromatography.
Wholly aromatic polyamides containing bridged biphenylylene groups, 1. Poly(3,8‐phenanthridinonediyl terephthalamide)
Authors: Kaneda Takaho , Ishikawa Seiji , Daimon Hiroshi , Katsura Toshio , Ueda Masahiro , Oda Kunio , Horio Masao
Published: April 2003

As a part of studies on wholly aromatic polyamides containing bridged biphenylylene groups, poly(3,8‐phenanthridinonediyl terephthalamide) (DAP‐T) was prepared from 3,8‐diaminophenanthridinone and terephthaloyl chloride. The solutions of DAP‐T samples in high concentration sulfuric acid exhibited optically different phases, depending on temperature and concentration, like those of poly(1,4‐phenylene terephthalamide) (PPD‐T). The phase diagram of the DAP‐T‐99,0% H2SO4 system was established and compared with that of the PPD‐T‐99,0% H2SO4 system. Both were essentially similar. The flow of high concentration dopes of DAP‐T and PPD‐T through spinneret holes showed non‐Newtonian characteristics. The liquid‐crystalline solutions of DAP‐T in 99,0% sulfuric acid were spun into fibers using water as a coagulant. The tensile strength and initial modulus increased with increasing degree of stretching between spinneret and collection roller. The annealing of fibers caused an increase in tenacity and modulus, and a tensile strength of 25 g/den and an initial modulus of 1 000 g/den could be reached. Both spun fibers and annealed fibers showed x‐ray diffraction patterns displaying distinct layer line streaks, from which the fiber period was estimated to be 17,2 Å. This agreed with the repeat distance in the direction of molecular axis calculated on the basis of extended chains with trans‐conformation.
Graft copolymerization of methyl methacrylate on chlorinated natural rubber, 3. Study of the interaction between chlorinated and organometallic compounds
Authors: Nogues P. , Dawans F. , Maréchal E.
Published: April 2003

The interaction of Ni[P(OR)3]4 (R = C2H5 or C6H5) with chlorinated rubber (CR) of CCl4 is studied. The results of the polymerization of methyl methacrylate (MMA) initiated by the system CR or CCl4Ni[P(OR)3]4 depend on the order in which the reagents are introduced. Trialkylphosphite, tetrakis(trialkylphosphite) nickel and the products resulting from the reaction of CCl4 or CR with Ni[P(OR)3]4 are characterized by 31P NMR. From this study, it appears that the initiation of polymerization by the system chlorinated compound‐nickel derivative does not involve the formation of free phosphite, which is at variance with previously reported assumption. 1H NMR study supports these results.
Effect of molecular weight on the crystallization kinetics of isotactic poly(1‐butene)
Authors: Cortazar Milagros , Guzman Gonzalo M.
Published: April 2003

Isothermal crystallization of isotactic poly(1‐butene) fractions by calorimetry and microscopy was studied for a range of molecular weights from 96 000 to 964000. An Avrami exponent of 2 was found indicating a two‐dimensional growth rate of the crystal, following a predetermined nucleation mode, proving that such an exponent is independent of both temperature and molecular weight. The temperature and molecular weight dependence of the growth rate of spherulites and overall crystallization rates was analyzed by means of the theoretical expression given by Hoffman and Lauritzen. The product of the lateral and basal surface free energies of the crystallites, σ·σe, increases with molecular weight and approaches its limiting values when a certain molecular weight is attained.
Oxygen‐ascorbic acid‐Copper(II) initiating system. A kinetic study of the polymerisation of methyl acrylate in aqueous medium
Authors: Reddy G. Gangi , Nagabhushanam T. , Santappa M. , Rao K. Venkata
Published: April 2003

Polymerisation of methyl acrylate (MA) initiated by O2‐ascorbic acid (AA)‐Cu2+ system was studied in aqueous medium at 40°C. The rate of polymerisation Rp, was found to increase, remain constant, and then decrease with increasing [Cu2+]. Rp was found to depend on [Cu2+]0,6, [AA]0, [O2]0,6, and [MA]1,3 in the increasing region, on [Cu2+]0, [AA]0, [O2]0,6, and [MA]1,6 in the constant region and on [Cu2+]−0,9, [AA]0, [O2]0,7, and [MA]2,0 in the decreasing region. Rate laws were derived assuming a plausible reaction mechanism for the different regions. Rp increased with ionic strength and decreased with [H2SO4,]. An initial increase, then steady state followed by a decrease in rate with temperature was noticed in the range 25 − 55°C. kp/kt1/2 values were calculated and compared with literature values. Chain lengths were determined viscometrically.
Nouvelle préparation de polychlorophosphazènes linéaires
Authors: Helioui Moncef , De Jaeger Roger , Puskaric Emile , Heubel Joseph
Published: April 2003

Polychlorophosphazenes 2 can easily be obtained by thermal condensation of dichlorophosphinoyliminotrichlorophosphorane (1) under atmospheric pressure at 240–290°C, pure POCl3 being eliminated. The different stages of the reaction were studied by chemical analysis, 31P NMR, IR spectroscopy, and thin layer chromatography. The procedure enables one to obtain polymers of low and high molecular weights. The samples do not contain any cyclic or reticular polymers. Species of low molecular weights can be separated from those with high molecular weights by treatment with heptane. The total yield of phosphorus is 100% with regard to the starting material. Substitution products (Cl by OCH2CF3) are obtained which are identical with those obtained with the polychlorophosphazenes prepared via classical methods.
Studies on chitin, 8. Modification reaction of chitin in highly swollen state with aromatic cyclic carboxylic acid anhydrides
Authors: Kurita Keisuke , Ichikawa Hiroyuki , Ishizeki Shinichi , Fujisaki Hitoshi , Iwakura Yoshio
Published: April 2003

Reaction of partially deacetylated chitin with aromatic cyclic carboxylic acid anhydrides such as phthalic anhydride, trimellitic anhydride, and pyromellitic dianhydride was successfully carried out under almost homogeneous conditions in organic aprotic solvents using highly swollen precipitates of water‐soluble chitin with about 50% deacetylation. The resulting amic acid‐chitins were converted into the corresponding imide‐chitins by heating. In addition to imidization, this heat treatment also promotes removal of acid anhydrides reacted at the hydroxyl group giving rise to the formation of selectively N‐substituted derivatives. These novel chitin derivatives exhibit a much improved solubility in organic solvents and aqueous alkaline solutions. As anticipated, the imide‐chitins, derived from trimellitic anhydride and pyromellitic dianhydride, showed reactivity toward amine under heterogeneous conditions, and the reaction capacities toward p‐chloroaniline were determined to be 4,2 · 10−4 and 4,6 · 10−4 mol · g−1, respectively.
Effects of substituents in aromatic amine N‐oxide and amine modifiers on ziegler‐type propylene polymerization catalyst performance
Authors: Karayannis Nicholas M. , Lee Sam S.
Published: April 2003

Studies of the effects of ring substituents in aromatic amine N‐oxide or amine modifiers on Ziegler‐type propylene polymerization catalyst performance are reported. Among sterically hindered amines or N‐oxides, the o,o‐dimethyl substituted derivatives provide the best stereospecificity with little loss in activity. On the other hand, m‐ or p‐substituted derivatives with electron‐withdrawing substituents were found to activate the catalyst, producing higher yields relative to the unmodified (TiCl3‐Al alkyl) catalyst system. The inductive and steric effects introduced by the modifiers in the catalyst system are discussed. Aromatic amine N‐oxides generally produce less active catalyst systems relative to their parent amines, owing presumably to a redox reaction between the N—O function and Ti3+.
Formaldehyde polymers, 30. Preparation of 5‐hydroxy‐4‐chromanones and 8‐hydroxy‐1‐tetralon and their properties as UV‐absorbers
Authors: Ninagawa Akira , Nakamura Masashi , Matsuda Haruo
Published: April 2003

5‐Hydroxy‐6,8‐dimethyl‐4‐chromanone (4a) and 8‐hydroxy‐5,7‐dimethyl‐1‐tetralon (4b) were synthesized from 6,8‐dimethyl‐4 chromanone (1a) and 5,7‐dimethyl‐1‐tetralon (1b), respectively. 5‐Hydroxy‐7‐methody‐2,2‐dimethyl‐4‐chromanone (6) was prepared from 5,7‐dihydroxy‐2,2‐dimethyl‐4‐chromanone (5). Cyclohexane solutions of 1a, 1b, 4a, 4b, 6, 5‐hydroxymethyl‐6,8‐dimethyl‐4‐chromanone (7), 3‐hydroxy‐2,6‐dimethyl‐4‐chromanone (8), and 2‐hydroxy‐4‐octyloxybenzonphenone (9) were irradiated. The photostability of these compounds was found to decrease in the following order: 4b > 4a, 6 > 9 > 1a, 1b. 7, 8. Poly(venyl chloride) films containing 5, 0 wt.‐% of 4a, 4b, or 6 were found to be stable against photooxidation.
Hydrogen bonding in monodisperse and polydisperse oligo(ethylene glycol)s
Authors: Teo Hoon H. , Marshall Alan , Booth Colin
Published: April 2003

Infrared spectra of monodisperse (DP ≤ 35) and polydisperse (average DP ≤ 45) oligo(ethylene glycol)s are recorded for melts and for solids over a temperature range (+70°C to ‐80°C). Spectra in the hydroxyl stretching region show that the solid monodisperse oligomers with DP ≤ 25 at temperatures well below the melting point have highly ordered lamella end surfaces with hydroxyl groups from adjacent lamellae hydrogen bonded in long chains, whereas the solid polydisperse oligomers of comparable chain length have disordered lamella end surfaces with hydroxyl‐ether as well as hydroxyl‐hydroxyl hydrogen bonding.
Synthèse et transformations chimiques des télomères de l'undécène‐10 oate de méthyle, 1
Authors: Belbachir Mohamed , Boutevin Bernard , Piétrasanta Yves , Rigal Gérard
Published: April 2003

Redox of radical telomerizations of methyl 10‐undecenoate (1) with different telogens such as CCl4, CCl3Br, CCl3CF3, HPO (OEt)P2 or different adducts of CCI4, on vinylidene chloride and chlorotrifluoroethylene, were studied. Chemical transformation of the end of the chains led to the corresponding difunctional compounds. Starting with these last compounds, polycondensation reactions were carried out.
Mechanistic implications of the end group structure in radical telechelic polybutadienes as studied by NMR
Authors: Bresler Lubov' S. , Barantsevich Eugene N. , Polyansky Victor I. , Ivantchev Sergey S.
Published: April 2003

270 MHz 1H NMR spectra were used to study of the structure of end groups and terminal monomeric units in polybutadienes produced by radical polymerization, initiated with hydrogen peroxide and a series of substituted benzoyl peroxides. The hydroxyl or aroyl groups were found to be bounded to the methylene end group of the 1,4‐cis‐, 1,4‐trans‐ or 1,2‐butadiene terminal units. The terminal units are richer in 1,2‐structures than the backbone due to the influence of hydroxyle or of the groups on the relative reactivity of carbons 1 and 3 in the allylic radical, formed by initiation. 1,2‐Units at the chain ends and in the backbone are predominantly joined to 1,4‐units; this results in a magnetic nonequivalence of the methylene protons in 1,2‐structures. Data are also presented on the extent of radical decarboxylation during initiation by substituted benzoyl peroxides and also on the introduction of solvent fragements in polybutadienes obtained by initiation with hydrogen peroxide in alcoholic media.
Refractive index increments of polyacrylamide and comments on the light scattering from its solutions
Authors: Stejskal Jaroslav , Horská Jitka
Published: April 2003

The refractive index increments of polyacrylamide for various wavelength were determined both in the usual solvents (water, ethylene glycol, formamide) and in those so far unused (ethanolamine, dimethyl sulfoxide). The values thus obtained are compared with the reported data. The necessity to employ anhydrous polyacrylamide samples is stressed. The question of the possible effects of ageing of solutions on the refractive index increment values is discussed. No ageing of solutions was observed at room temperature; at elevated temperatures, the amide groups of the polymer undergo hydrolysis in water.