bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth mechanism of crystals of glycine/S‐methyl‐L‐cysteine copolymer in the course of polymerization
Authors: Kim Kea Yong , Kōmoto Tadashi , Kawai Tohru
Published: April 2003

In order to examine the growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N‐carboxy anhydride (2,5‐dioxo‐1‐oxa‐3‐azacyclopentane) and S‐methyl‐L‐cysteine N‐carboxy anhydride (4‐methylthiomethyl‐2,5‐dioxo‐1‐oxa‐3‐azacyclopentane) was studied in acetonitrile. In all the polymerization systems, the crystal growth occurs through formation of the cross‐β‐type structure. The high conversion in the glycine‐rich systems is accounted for by the widening of the cross‐section of the β‐chain in the backbone crystal, due to the introduction of S‐methyl‐L‐cysteine residues into the polyglycine chain. On the other hand, the narrowing of the cross‐sectional area per chain in the skeleton crystals of the oligomer gave rise to the lowering of the conversion in the S‐methyl‐L‐cysteine‐rich systems. This shows the importance of the effect of the cross‐sectional area of the oligomer chain (of the β structure) in the crystal formed in the begining relative to that of the growing (α‐helical) chain. The glycine residue seems to be incorporated into the crystalline lattice of the S‐methyl‐L‐cysteine and vice versa.
Die γ‐induzierte copolymerisation von vinylfluorid und vinylidenfluorid
Authors: Ellinghorst Guido , Vierkotten Detlev , Hagiwara Miyuki , Hummel Dieter O.
Published: April 2003

The 60Co‐γ‐induced copolymerization of vinyl fluoride (VF) and vinylidene fluoride (VF2) was investigated for the polymerization temperatures 273 K, 253 K, and 233 K. The dependency of the over‐all reaction rate and the over‐all activation energy on the composition of the monomer feed is evaluated. The copolymerization parameters were determined as r1=5,23 and r2=0,06 (VF≙M1). The change of over‐all reaction rate with monomer feed is discussed. By means of a mathematical treatment of the kinetical behaviour of non‐steady‐state reactions, which was modified for the case of copolymerization, the influence of termination and propagation on the over‐all reaction rate was determined separately.
A comparison of the absolute reactivity of monomers, 1. Kinetic study of radical polymerization of acrylamide and methacrylamide, initiated by manganese(III) acetate
Authors: Elayaperumal P. , Balakrishnan T. , Santappa M.
Published: April 2003

The kinetics of polymerization of acrylamide (AAM) and methacrylamide (MAM) with manganese(III) acetate as thermal initiator was studied. In the temperature range between 303 and 313 K, the initial rate of polymerization follows the relation:

The rate of initiation of the polymerization was determined from the rate of decomposition of manganese(III) acetate. The reactivity of the two monomers under the same conditions was compared.
A study of structural order in various polyethylenes at elevated temperatures
Authors: Preedy John E. , Wheeler Ernest J.
Published: April 2003

Changes in several structural properties of an ethylene homopolymer have been measured and compared with those of ethylene copolymers with simple and complex branchings over a range of temperature from ambient to above the normal [melting temperature]. In the case of the first two polymeric types, a clear behavioural pattern was observed in which, with rising temperature, a small rotation of the back‐bone chains was followed by melting and recrystallization, the latter two processes occurring in the range from about 110°C to the melting temperature. In the upper temperature range ethyl branches were also rejected from the crystalline lattice. Around the melting temperature, a change from the orthorhombic to the hexagonal phase was suggested as a possibility. The thermal behaviours of the copolymers with the more complex branchings were found to be more complicated with melting and recrystallization occurring over various temperature ranges. No simple relationship appeared to exist between the numbers and shapes of the complex branchings and the structural changes produced in the copolymers by increasing temperature.
Ionische polymere aus 1,4‐bis(chloracetyl)piperazin und difunktionellen tertiären aminen durch quaternisierende additionspolymerisation
Authors: Weiss Josef , Schindlbauer Hellmuth
Published: April 2003

New water soluble polyelectrolytes were prepared by quaternizing addition polymerization of 1,4‐bis(chloroacetyl)piperazine (1) with N,N,N′,N′‐tetramethylhexamethylenediamine (2), 1,4‐dimethylpiperazine (3), 1,4‐diazabicyclo[2,2,2]octane (4), and N,N‐dimethyl‐(4‐dimethylaminomethyl)benzylamine (5). DMF, DMF/water, and water were used as reaction media. The polymer synthesized from 1 and 2 in DMF/water (4:1) showed a very high molecular weight and an intrinsic viscosity of 37ml/g, which is the highest value found for such compounds so far.
Syntheses and properties of poly(iminoethylene) containing nucleic acid bases
Authors: Shimidzu Takeo , Konishi Yoshiyuki , Murakami Akira
Published: April 2003

Poly{N‐[2‐(adenin‐9‐yl)ethyl]iminoethylene hydrochloride‐co‐iminoethylene} (1) and poly{N‐[2‐(thymin‐1‐yl)ethyl]iminoethylene hydrochloride‐co‐iminoethylene} (2) were synthesized by alkylation of poly(iminoethylene) with 9‐(2‐chloroethyl)adenine and 1‐(2‐chloroethyl)thymine, respectively. In addition, the alkylation of a commercial poly(ethylenimine) with 9‐(2‐chloroethyl)adenine was carried out. These model compounds interact with nucleosides to form the complementary base pairs. In contrast to that, the order of interaction of those model compounds with nucleotides is the following one: purine‐purine >purine‐pyrimidine>pyrimidine‐pyrimidine. The addition of salt compensates the interaction between 1 and Ado‐5′‐P completely, whereas that between 1 and Urd‐5′‐P is only slightly reduced. This shows that complementary base‐base interaction is not appreciably affected by ionic strength.
Über die druckabhängigkeit der viskoelastischen und physikalisch‐chemischen eigenschaften von polymeren, 3. Darstellung des druckeinflusses auf das spezifische volumen im technischen temperatur‐ und druckbereich
Authors: Karl Veit‐Holger , Asmussen Frithjof , Ueberreiter Kurt
Published: April 2003

A reduction formula for the calculation of the specific volume v at any temperature T and any pressure P is derived; it consists of the two equations:

The parameters ξ, ζ and ψ can be easily calculated from values in the literature, and therefore only a volume‐temperature curve at atmospheric pressure has to be measured.
Viskositäts‐molekulargewichts‐beziehung für polyamid‐12
Authors: Hammel Reinhart , Gerth Christian
Published: April 2003

Light‐scattering and viscosity measurements were performed on dilute solutions of polyamide‐12 in 1,1,1,3,3,3‐hexafluoro‐2‐propanol at 25°C. The [η]‐M̄w relationship was determined to be [η]=8,43·10−4·M̄w0,68 dl g−1.
Untersuchungen zur Thermolyse und zur Sauerstoff‐Stabilität der 4π + 2π‐Diels‐Alder Addukte des Styrols
Authors: Kauffmann Harald Friedrich
Published: April 2003

The 4π + 2π‐Diels‐Alder cycloadduct 1 involved in the spontaneous polymerization of styrene was investigated under conditions, where bimolecular reactions with styrene leading to a consumption of 1 can be neglected. For this reason 1 was (a) submitted to thermolysis in an inert solvent (toluene) at different temperatures (90, 100 and 110°C) and (b) oxidized with an excess of oxygen in styrene at room temperature. The reactions were followed spectrometrically at the wavelength λ = 325 nm and analyzed in terms of a first order reaction. The results show strong evidence for the involvement of two diastereomers (1a and 1b) of different reactivity. This is in qualitative and quantitative agreement with the two isomers' concept, which had been deduced previously from kinetic analysis of the formation of 1 during the thermal polymerization of styrene. Rate constants and activation energies as well as possible reaction pathways are given.
13C NMR sequence analysis, 10. Synthesis and spectroscopic characterization of sequence polypeptides containing taurine, γ‐aminopropanesulfonic acid, and sulfanilic acid
Authors: Kricheldorf Hans R. , Schultze Joachim
Published: April 2003

Starting with benzyloxycarbonyltauryl chloride (1) and benzyloxycarbonylsulfanilyl chloride as well as with glycine ethyl ester and β‐alanine methyl ester several Z‐tripeptides (3a–c, 7a–d) were synthesized. The sulfanilyl peptides 7a–d were converted to the 4‐(isothiocyanato)benzenesulfonyl dipeptides 9a–d, which were condensed to the sequence polymers 10a–d at 140–170°C. From the Z‐tauryl peptides 3a–c the free tripeptides 5a–c were prepared and condensed to the ternary sequence polypeptides 16a–c using the phosphorus triazolides 13 and 14 as condensing reagents. Starting with dipeptides 4a–d and 6a–d the binary sequence polymers 15a–d and 17a–d were obtained in like fashion. The 1H NMR spectra of these oligo‐ and poly‐peptides were recorded in trifluoroacetic acid and 13C NMR spectra of the polypeptides in dimethyl sulfoxide and trifluoroacetic acid. Both 1H NMR and 13C NMR spectra allow characterization of and clear distinction between isomeric oligopeptides, i.e. Z‐Sulf‐Gly‐β‐Ala/Z‐Sulf‐β‐Ala‐Gly, and isomeric polypeptides, i.e. poly(Tau‐γ‐Abu)/poly(γ‐Aps‐β‐Ala) or poly(Tau‐Gly‐β‐Ala)/poly(Tau‐β‐Ala‐Gly). A change of the solvent from dimethyl sulfoxide to trifluoroacetic acid results in a downfield shift of the 13C‐carbonyl signals of the sequence polypeptides by about 10ppm, whereas the other C‐signals show only small effects (<2ppm). The influence of monomer structure, sequence, and solvent on chemical shift is discussed.
Polymere imidazolcarbonsäuren, 2. Über das schwermetallionenbindungsvermögen von chelatharzen mit 4,5‐sicarboxyimidazolyl‐gruppen
Authors: Manecke Georg , Schlegel Rainer
Published: April 2003

The swelling behaviour, the time‐dependence of the uptake of Cu2+‐ions, and the pH‐dependence of the uptake of Cu2+‐, Ni2+‐, Cd2+‐, Zn2+‐ and Mg2+‐ions of crosslinked poly[1‐(4,5‐dicarboxy‐1‐imidiazolyl)ethylene] (1) and poly{1‐[p‐(4,5‐dicarboxy‐2‐imidazolyl)phenyl]ethylene} (2) were investigated. Both resins have a high selectivity for heavy metal ions. For resins 1 the uptake of heavy metal ions in the presence of an excess of EDTA was studied. Furthermore the possibility to remove Hg2+‐ions from aqueous alkalichloride solutions by resin 1 was investigated.
Kinetics of the reaction of a glycol with a diisocyanate
Authors: Yilgör İskender , Orhan Erdal H. , Baysal Bahattin M.
Published: April 2003

The reaction between poly(ethylene oxide) glycol (α‐hydro‐ω‐hydroxypoly(oxyethylene)) and methylenebis(1,4‐cyclohexylene) diisocyanate was studied at 70, 80 and 90°C. The course of the reaction was followed by determining the isocyanate content of the reaction mixture at appropriate time intervals. The data thus obtained were analyzed by taking into consideration the glycol‐ and urethane‐catalyzed reactions separately. It was found that although the urethane‐catalyzed reaction was faster in the temperature range studied, its relative importance decreased with increasing temperature.
Radical reactions initiated by chelate complexes of transition metals, 17. Solvent effect on polymerization of methyl methacrylate initiated by copper(II) 2‐aminoethanolate
Authors: Mapunda‐VlčKová Jana , Bartoň Jaroslav
Published: April 2003

The solvent effect on radical Polymerization of methyl methacrylate initiated by copper(II) 2‐aminoethanolate (Cumea) or by the system Cumea‐reducing agent (H2NCH2CH2OH, CCl4) is discussed. In the first case, where the initiating radical is formed from a Cumea‐MMA complex, the solvent influences the equilibrium of the complex‐forming reaction and thus also the initiation reaction. Further, in this system also primary radical termination and degradative chain transfer are operative. In the initiation by the system Cumea‐reducing agent, the non‐ideal course of polymerization is due to primary radical termination and degradative chain transfer.
Additive effect of poly(ethylene oxide), 1 acceleration effect of poly(ethylene oxide) in several nucleophilic reactions
Authors: Hirao Akira , Nakahama Seiichi , Takahashi Mitsuru , Yamazaki Noboru
Published: April 2003

The additive effect of poly(ethylene oxide) (PEO) in several nucleophilic reactions, such as the oxidation of trans‐stilbene with potassium permanganate, the alkylation of potassium acetate and diethyl benzylsodiomalonate as well as the Williamson reaction of sodium phenoxide with alkyl bromides was investigated and compared with that of dibenzo‐18‐crown‐6 (crown ether). A marked effect by PEO was observed under certain conditions, which was explained by a cooperative coordination of the oxygen atoms of PEO with metal cations promoting ion dissociation and resulting in the observed remarkable rate acceleration.
Polybutadiènes hydroxytéléchéliques, 1. Microstructure, fonctionnalité et mécanismes réactionnels. Etude par résonance magnétique nucléaire du proton et du carbone 13
Authors: Fages G. , Pham Q. T.
Published: April 2003

The examination of H2O2‐initiated hydroxytelechelic polybutadienes polymerized by H2O2 initiation by 1H NMR and 13C NMR allows the identification of three main primary alcoholic groups: α‐unsaturated, β‐substituted/α‐unsaturated and γ‐unsaturated. From 1H NMR accumulated spectra, it has been possible to calculate the number average OH‐functionalities of the polymers. These should be slightly under‐estimated because of the possible presence of secondary and tertiary alcoholic groups whose concentrations, however, should be very small. The nature of these alcohol functions gives information concerning the likely initiation, transfer and termination mechanisms of the radical polymerization of butadiene by H2O2 in alcoholic media.
Studies on aqueous polymerization of acrylonitrile. Cerium(IV)/acetaldehyde redox system
Authors: Ahmed K. Riaz , Natarajan L. V. , Anwaruddin Q.
Published: April 2003

The thermal polymerization of acrylonitrile initiated by the cerium(IV)/acetaldehyde (A) redox system was carried out at 25°C, and the rate of monomer disappearance, –d[M]/dt, was followed by gravimetry and the rate of cerium(IV) disappearance –d[Ce(IV)]/dt by titrimetry. –d[M]/dt was found to be directly proportionsl to [M]3/2, [A]1/2, and [Ce(IV)]1/2. –d[Ce(IV)]/dt was found to be directly proportional to [Ce(IV)] and [A]. A reaction scheme is given together with the kinetic expressions. The activation energy for the overall rate was found to be 67,24kJ.mol−1 (16,06kcal.mol−1), and the value of the second order rate constant kr, was obtained as 2,481.mol−1s−1.
Linear oligopeptides, 48. Synthesis, characterization and conformational analysis in solution of monodisperse protected homo‐oligomers derived from L‐norleucine
Authors: Bonora Gian Maria , Toniolo Claudio
Published: April 2003

A series of N‐ and C‐protected L‐norleucine homo‐oligomers from dimer to heptamer was prepared by the dicyclohexylcarbodiimide and acyl azide coupling methods. In the course of the synthetic approach tert‐butyloxycarbonyl as the N‐protecting and methoxy as the C‐protecting end groups were employed. The monodisperse oligomers synthesized in this manner were characterized and found to be chemically pure. A polarimetric investigation in a structure disrupting solvent also indicated that all reactions proceeded with complete retention of the configuration. By UV absorption and far‐UV CD it was shown that these peptides may exist in predominantly β‐form, statistical coil, or partially folded conformation depending upon molecular weight and nature of solvent.
Venetzung von Amylose mit Epichlorhydrin, 1. Untersuchung der Phase vor der Gelbildung
Authors: Pfannemüller Beate , Sperlich Marianne
Published: April 2003

Cross‐linking of amylose with 1‐chloro‐2,3‐epoxypropane (epichlorohydrin) was studied in aqueous 1M NaOH solution in dependence of the amylose concentration, the mole ratio of anhydroglucose to epichlorohydrin, and the degree of polymerization of the primary chains. Structural changes which occur during the pre‐gel phase were followed by chemical analysis, by viscosity and light scattering measurements, and by the optical properties of the iodine complex. The results indicate in the early stage of the process that the introduced glycerol diether groups are mainly present as intermolecular cross‐links as seen from a rapid increase in the molecular weight. With further progress of the reaction a decrease of particle density may be derived from the unusual dependence of intrinsic viscosity and mean square radii of gyration on molecular weight. The results are discussed being due to association of amylose segments by hydrogen bonds in the weakly cross‐linked products and a solubilizing effect of monoether substituents introduced later on.
Viscoelastic spectra of ethylene/propylene copolymers obtained with catalytic systems having a different steric regulation
Authors: De Candia Francesco , Maglio Gianni , Palumbo Rosario , Romano Gennaro , Zambelli Adolfo
Published: April 2003

The dynamic mechanical properties of ethylene/propylene copolymers prepared by soluble catalysts based on vanadium salts and alkylaluminium compounds were investigated. The properties of the copolymers were found to depend not only on the chemical composition, but also on the polymerization temperature and on the stereoregulating character of the catalyst. The mechanistic implications of these findings are discussed.
Intermittierende Laserbeleuchtung für die Interferenz‐ und Schlierenoptik einer analytischen Ultrazentrifuge
Authors: Floßdorf Josef , Schillig Henning , Schindler Klaus‐Peter
Published: April 2003

A simple and inexpensive illuminating system is described that improves analytical ultracentrifugation performed with interference and schlieren optics. Its essential part is a modulatable laser synchronized to the rotor speed by the multiplexer of the absorption scanner of the Beckman Model E ultracentrifuge. Particularly in connection with the Rayleigh interference optics, this method combines high fringe contrast and resolution with the advantages of the use of multicell rotors: ease of operation, efficiency and equalness of experimental conditions for each sample in the rotor. Up to six cells can be run simultaneously, but still individual pictures can be taken of each of them. A motor‐driven camera accumulates in an arbitrary sequence up to 250 pictures. This modification has been mainly designed for the Beckman Model E but can also be adapted to other analytical ultracentrifuges.
Synthèse et polymérisation de polyméthacrylates porteurs de la quinine. Etude comparée de la toxicité et de l'immunogénicité des formes libres et polymériques
Authors: Pinazzi Christian , Rabadeux Jean Claude , Pleurdeau Alain , Nivière Pierre , Paubel Jean Pierre , Benoit Jean Pierre
Published: April 2003

Quinine was linked to 2‐chlorocarbonyloxyethyl methacrylate (6) by a carbonate bound. This monomer 7 was characterized by usual spectroscopic methods and polymerized by a radical process. The resultant polymer 4 was biologically tested by toxicity and immunology studies on rabbit. Polymer 4 was analyzed by IR and NMR spectroscopy and compared with the polymer obtained by chemical modification of poly(2‐hydroxyethyl methacrylate) (1).
Cyclopolymerization, 7. Radiation induced polymerization of N‐substituted dimethacrylamides in the solid and supercooled liquid states
Authors: Kodaira Toshiyuki , Ni‐Imoto Masaki , Aoyama Fumio , Yamaoka Hitoshi
Published: April 2003

The effect of phases, viz., a crystalline, a glassy, and a supercooled liquid state, on the cyclopolymerization of N‐substituted dimethacrylamides 1, initiated by ionizing radiation, was examined. In both the crystalline and supercooled liquid states, 1 was polymerized to give completely cyclized polymers, whereas no polymerization occurred in the glassy state. The structural investigations showed that the polymerization in the supercooled liquid state afforded polymers with the same structure as that of polymers formed in the liquid state, while the polymerization in the crystalline state yielded polymers with some difference in structure. Irrespective of the matrices where polymerizations were carried out, poly(1) obtained are amorphous, and the rate determining step was found to be an intramolecular cyclization reaction, by ESR spectra of propagating radicals. The results thus obtained suggest that the polymerizations of dimethacrylamides 1 in the solid and supercooled liquid states proceed through a virtually identical mechanism with that developed for the polymerization in the liquid state, but the matrices influence the polymerization process to some extent.
Reaktive träger zur immobilisierung von enzymen ausgehend von polyacrolein
Authors: Manecke Georg , Pohl Robert
Published: April 2003

Polyacrolein (1) was transformed into poly(allyl alcohol) (2), poly[1,1‐bis(hydroxymethyl)ethylene] (5) and N‐substituted poly(vinylmethanimine)s 8, 9a–c and 10. By subsequent reactions on these polymers reactive carriers with isothiocyanato‐, diazo‐, and azido groups were formed or by reaction with BrCN activated carriers were obtained which are able to bind enzymes covalently. The binding abilities of some reactive carriers were investigated for papain and trypsin. The effect of the pH‐value during the coupling reaction, the amount of offered enzyme, the content of the reactive groups per g carrier and the effect of different reactive groups on the binding ability of the carriers were investigated. For immobilized papain and trypsin the enzymatic activity, the pH‐optimum of their activity, and the apparent Michaelis constant KM(app) were determined. The dependence of the activity on the temperature was also investigated.
3‐ and 4‐dimethylaminobenzyl acrylate and methacrylate and their polymers
Authors: Hrabák František , Hynková Vlasta , Pivcová Hana
Published: April 2003

3‐ and 4‐dimethylaminobenzyl acrylates (3 and 4) and methacrylates (1 and 2) were prepared and their densities, IR and NMR spectra are recorded. In order to evaluate their reactivity towards benzoyl peroxide, the rate constants of the reaction of benzoyl peroxide with 3‐ and 4‐dimethylaminobenzyl alcohols and 3‐ and 4‐dimethylaminobenzyl acetates were determined. The reactivity of the esters prepared in this work appeared to be weaker than that of an N‐aryl‐N‐alkylaminoalkyl methacrylate. The blocks of homopolymers of these esters and of their copolymers (mole ratio 1:1) with styrene and methyl methacrylate are crosslinked. Both homopolymers and copolymers of 1 and 3 are more stable in polar solvents and on heating than polymers of 2 and 4. The copolymerization parameters of 1 and 2 with styrene are close to the copolymerization parameters of methyl methacrylate with styrene.
Coenzyme models 14 Addition reaction of sulfite ion to monomeric and polymer‐bound flavins
Authors: Shinkai Seiji
Published: April 2003

Rate and association constants (kf and K, respectively) for the addition of sulfite ion to three flavins (including isoalloxazines) and to four flavin‐containing polymers were determined at 30°C in aqueous systems. The forward reaction rates for polymer‐bound flavins at an ionic strength of μ = 0,18 mol/l were enhanced by factors of 15–37 and the association constants by factors of 7–19, compared with those of the corresponding monomeric flavins. A linear log kf – log K relationship was found for monomeric flavins. While the parameters for polymer‐bound flavins deviated to the upper area by 0,5–1,0 log units. An increase in the salt concentration suppressed markedly the reaction parameters for polymer‐bound flavins, and the log kf – logK plot at μ = 0,7 mol/l was involved in the linear relation for monomeric flavins.
The charge‐transfer complex maleic anhydride‐tetrahydrofuran and its role as photosensitizer in the polymerization of methyl methacrylate
Authors: Torres Amelia , Castaño Fernando , Alvariño José M.
Published: April 2003

The formation of a charge‐transfer complex (CTC) between maleic anhydride and tetrahydrofuran both in bulk and in chloroform solution is proved by electronic absorption spectroscopy, and its association constant at 35°C is determined by this technique and by 1H NMR. The effect of irradiation with monochromatic 350 nm light upon the fluorescence spectrum of the CTC excited with this same radiation is studied. Significant changes are noted in the bulk system, but the changes are much smaller in the presence of methyl methacrylate which is simultaneously polymerized. The effect of oxygen on the polymerization is discussed.
Radius of gyration versus molar mass relations from light scattering for polydisperse non‐gaussian chain molecules. Polystyrene in toluene and short DNA‐fragments in aqueous NaCl‐solution
Authors: Oberthür Radulf Christoph
Published: April 2003

Theoretical relations for the dependence of the z‐average radius of gyration Rz as a function of the mass average molar mass Mw are derived for expanded coils, persistence coils with persistence of direction, persistence coils with persistence of direction and curvature, and for needles, all exhibiting a Schulz‐distribution of their molar masses. These relations are applied to experimental data from light scattering of polystyrene in toluene and DNA‐Na in aqueous NaCl‐solution of 200 mol NaCl per m3 at room temperature. In the case of DNA it becomes evident that the double helix shows no important persistence of curvature and that the experimental data can be described adequately by a persistence chain with mere persistence of direction and a statistical chain element b = (999±33). 10−10 m, corresponding to a persistence length a = (500±17). 10−10 m.
Die thermische Polymerisation von Methylmethacrylat, 1. Polymerisation in Substanz
Authors: Stickler Manfred , Meyerhoff Günther
Published: April 2003

Special purification of the monomer and careful preparation of the reaction setup allowed a thorough study of the spontaneous thermal polymerization of methyl methacrylate over a wide range of temperatures (0–140°C). The rates of polymerization are notably lower than the few data previously reported in literature, and the degrees of polymerization slightly higher. The thermal initiation reaction is superimposed by radical production due to the natural ionising radiation (cosmic radiation etc.). This additional initiation becomes significant at temperatures below 60°C. New and more reliable monomer chain transfer constants are given.
Strukturelle Effekte in Systemen MnLi/Butadien/Styrol
Authors: Melenevskaya Elena , Sgonnik Vladimir , Dolinskaya Eleonora , Erussalimsky Boris
Published: April 2003

The structure of the butadiene unit C4H6 in the hydrolysis products of the oligomers RMnC4H6Mm'Li and RMnC4H6Li (where R is sec‐butyl, M and M' are perdeuterobutadiene or styrene) was estimated by the use of IR‐ and NMR‐spectroscopy. The dependency of the C4H6‐structure on the nature of both the preceding unit M and the attacking monomer M' was investigated. The variation of the concentration of the organolithium compounds during the oligomer synthesis on the one hand, and during their hydrolysis on the other hand, showed a dependency of the C4H6‐structure on the conditions of the respective experiments.
Copolymerization of carbon dioxide and epoxypropane by using cobalt(II) acetate and acetic acid
Authors: Soga Kazuo , Hyakkoku Kyoko , Ikeda Sakuji
Published: April 2003

The copolymerization of carbon dioxide and epoxypropane was investigated at 80°C in dioxane by using cobalt(II) acetate as catalyst in the presence of acetic acid. The addition of acetic acid hardly diminishes the copolymer yield, but the number average molecular weight of the copolymer decreases in proportion to the concentration of acetic acid. The 1H NMR spectrum of the copolymer displays a very strong peak due to the methyl protons attached to an ester carbonyl group (OCOCH3). From these results it has been concluded that acetic acid causes a transfer reaction which leads to acetoxy end groups (cf. Eq. (14) below). Some other carboxylic acids, such as C6H5COOH, ClH2CCOOH, Cl2HCCOOH etc., were found to cause similar transfer reactions, too.
Cyclo‐copolymerization of 1,6‐diene with monoolefin, 2. The copolymer composition equation and the relative rates of addition in the cyclo‐copolymerization of diallyl ether with maleic anhydride and fumaronitrile
Authors: Fujimori Kiyohisa
Published: April 2003

A copolymer composition equation is derived for the cyclo‐copolymerization of a 1,6‐diene with a monoolefin that do not homopolymerize. The theory is applied to the free radical copolymerization of diallyl ether (DAE) with maleic anhydride (MA) and to that of DAE with fumaronitrile (FN). Both systems fall in the special case where there are no unreacted CC bonds left in the copolymer. The copolymer compositions are between 1:1 and 1:2 (=[diene]:[monoolefin]) over a wide range of monomer feed composition. The reactivity ratios obtained from the equation indicate that for the DAE/MA system, the intramolecular cyclization of the uncyclized DAE radical is 2,9 times more effective than the addition of MA monomer to the uncyclized DAE radical, and that for the system of DAE/FN, the intramolecular cyclization of DAE radical is 6,7 times more effective than the addition of FN monomer.
Bestimmung physikalischer konstanten durch die funktion y/x = a + b·x in der lösungsviskosimetrie, ebulliometrie und dampfdruckosmometrie
Authors: Melsheimer Jörg , Scotobayashi Hideto
Published: April 2003

Calculations of most probable values on the basis of the equations y = a · x + b · x2, y/x = a + b · x and x = a* + b* · y/x have been carried out with data from solution viscometry, ebulliometry, and vapor pressure osmometry. The calculations carried out with the method of least squares give different coefficients for the equations taken as a basis. However equal coefficients are obtained with the method of Deming in which the measured data are weighted. Furthermore the so calculated slopes of the equations differ from those determined by the method of least squares whereby the differences depend upon the type of equations and upon the deviation of the measured data.
Effects de la substitution du cycle pyrrolidone‐2 par un groupement méthyle sur le processus de polymérisation
Authors: Deratani André , Sekiguchi Hikaru
Published: April 2003

We tried to evaluate the reason for the very low polymerizability of methyl derivatives of 2‐pyrrolidone in the presence of anionic polymerization catalysts. The polymerizability estimated from the influence of the methylated group on the reactivity of the lactam ring (steric, inductive, and thermodynamic factors) does not agree with the experimental results of homopolymerization and copolymerization of 2‐pyrrolidone. The substitutional effects on the propagation process were analyzed and an explanation which is based on the slow‐down of the molecular growth and the crystallization of the reaction mixture is proposed. Thus, in copolymerizations with a small percentage of substituted lactams, the propagation is very slow with regard to the crystallization, which would allow a quick encagement of the active site by hydrogen bonds, and lead to the spontaneous blocking of polymerization. If this percentage increases, the crystallization cannot take place, and this would, as a consequence. favor all the secondary reactions leading to the formation of bicyclic dimer and oligomers.

A “chain multiplication” reaction was found in some cases.
Charge‐transfer complex between p‐oxathiene and maleic anhydride and its relative reactivity in alternating copolymerization
Authors: Iwatsuki Shouji , Itoh Takahito
Published: April 2003

Charge‐transfer complex formation and alternating copolymerization of p‐oxathiene (POT)‐maleic anhydride (MAnh) system were studied. Relative reactivity of POT‐MAnh complex was obtained from three kinds of terpolymerizations. For example, in terpolymerization of POT, MAnh and acrylonitrile (AN), monomer reactivity ratios of POT‐MAnh complex and AN were found as r1 (complex)=55,8 and r2 (AN)=0,0176 at 60°C. POT‐MAnh, p‐dioxene‐MAnh and vinyl ether‐MAnh systems were compared in relative reactivity and some physical properties concerning charge‐transfer complex. The reactivity of those MAnh complexes was found to be controlled more significantly by some properties related to electron‐donating power of donors rather than by resonance and polarity terms of separate donor monomers.
Regular copolyamides, 7. Water absorption in regular copolyoxamides
Authors: Tirrell D. , Grossman S. , Vogl O.
Published: April 2003

Water absorption at 93% relative humidity and 25°C was determined for 12 regular aliphatic/aromatic copolyoxamides. The equilibrium water absorption ranges from 7% to 30%, varied with the polymer structure and is highest in polymers with high amide concentration. The water absorption is reversible and seems to consist of a two‐step process, rapid absorption of water by polymer followed by a slower second stage as equilibrium is approached. These polymers have low crystallinity and the water absorption does not occur in crystalline regions. All water is bound to the polymer; it may be freed by heating the hydrated polymer above 100°C, but rebinds completely at room temperature.
Sequenzlängenverteilungsanalyse der 1,2‐Einheiten in Polybutadienen an Hand der Olefin‐Polymeres/Metathese‐Reaktion; ein Weg zur Darstellung von mono‐ und disubstituierten Cyclopenten‐ wie auch Cyclohexen‐Verbindungen
Authors: Thorn‐Csányi Emma , Perner Helmut
Published: April 2003

By means of metathetical degradation of polybutadienes it is possible to determine 1,4‐B‐(1,2‐B)1–3‐1,4‐B sequences. The metathetical 1,2‐butadiene (1,2‐B) sequence lengths distribution analysis may be used for the synthesis of substituted cyclopentene and cyclohexene derivatives.
Kinetics of inhibited or retarded polymerization. Investigations on the cerium(IV)/toluene/acrylonitrile system
Authors: Singh Baishnab C. , Misra Basanta K. , Rout Anuradha , Mallick Nigamananda , Rout M. K.
Published: April 2003

The kinetics and mechanism of the inhibiting action of toluene on the Ce(IV) initiated polymerization of acrylonitrile were studied together with the effects of [M], [Ce(IV)], [Toluene], [HClO4], [NaClO4], and [Acetic acid] on the rate of polymerization. The values of composite rate constant kkt/kpkoki for toluene (and substituted toluenes) was calculated by plotting [M]/Rp versus [M]−1. A very significant observation in the present study was that the plot of [M]/Rp versus [M]−1 gave a negative intercept, which seems to be a general observation for all inhibiting substrates. On the basis of the experimental data, it could be concluded that the benzyl radical obtained by hydrogen abstraction, and not a chain transfer, is responsible for the inhibition.
Chemische synthese verzweigter polysaccharide, 7. Zur frage des abbaus der polysaccharid‐hauptkette bei verzweigung über glykosidische bindungen
Authors: Pfannemüller Beate , Berg Annette
Published: April 2003

6‐Trityl‐2,3‐dicarbanilyl and 2,3‐dicarbanilyl derivatives of amylose and cellulose have previously been used as a backbone to introduce oligosaccharide branches by (1 → 6) glycosidic bonds. Possible degradation prior and during the glycoside coupling was now followed by light scattering measurements on each step of derivatization. The results obtained with derivatives of technical and synthetic amyloses indicate that some degradation may occur in the tritylation reaction and possibly in the conversion to the 6‐trityl‐2,3‐dicarbanilate. In the following steps, e.g. detritylation and glycosidic condensation of glucose and maltose derivatives under the conditions applied, degradation appears to be almost absent. In corresponding studies with cellulose derivatives problems arise mainly in the tritylation step. The results of the light scattering and viscosity measurements are discussed with respect to the molecular conformation.
Stereoselection in the polymerization of racemic propylene sulfide
Authors: Marchetti Massimo , Chiellini Emo , Sepulchre Maurice , Spassky Nicolas
Published: April 2003

Elution with different solvents of high molecular weight polymers of racemic propylene sulfide, prepared by stereospecific catalysts and supported on optically active polymers such as poly[(S)‐3‐methyl‐1‐pentene] and poly[(L‐dilactide)], makes it possible to separate polymeric fractions having opposite optical rotation in the former case, whereas in the latter no selective separation occurs. Although the degree of separation is less than 5%, mainly due to the poor efficiency of the separation process (5%), it is possible to recognize the cadmium tartrate catalyst as more efficient with respect to diethylzinc/racemic diol system in the stereoselective polymerization of propylene sulfide. The use of an optically active diol in the latter system promotes a stereoselection comparable to that of the former system, thus substantiating the specific role of heterogenous catalytic sites in controlling the stereochemistry of the chain propagation.
The temperature coefficient of the unperturbed dimensions of poly(pentachlorophenyl methacrylate)
Authors: Radic Deodato , Gargallo Ligia
Published: April 2003

Values of the temperature coefficient of the mean square unperturbed dimensions dln(r/dT) for poly(pentachlorophenyl methacrylate) are obtained from viscosity vs. temperature data under two different conditions: (a) viscosity determinations in several different solvents each at its Θ‐temperature and (b) viscosity determinations in a thermodynamically good solvent with a similar chemical structure as compared to the repeating unit. An anomalous temperature dependence of the viscosity was observed in o‐dichlorobenzene for this polymer. The results obtained from both conditions are compared and their limitations and interpretations are discussed.
Über Polyarylenalkenylene und Polyheteroarylenalkenylene, 9. Synthesen und Charakterisierung von Poly(5‐methylthiazolo‐[4,5‐f] benzthiazolium‐2,6‐diylvinylenarylenvinylen)en und einigen Modellverbindungen
Authors: Koßmehl Gerhard , Bocionek Peter , Manecke Georg
Published: April 2003

Starting from 2,3,6‐trimethylthiazolo[4,5‐f] benzothiazolium perchlorate (2b) some poly(5‐methylthiazolo[4,5‐f] benzothiazolium‐2,6‐diylvinylenarylenevinylene)s (11a–c) and some corresponding model compounds (10a–c) were prepared via Knoevenagel condensation with mono‐and dialdehydes (4 and 6) of the benzene and thiophene series. Additional series of model compounds (5a–c, 7a–c, 8a–f, and 9a–f) were obtained from 2,3,6‐trimethylthiazolo[4,5‐f]benzothiazolium iodide (2a) or 2,3‐dimethylbenzothiazolium iodide (3a), respectively, or from the perchlorates (2b and 3b) submitted to the same reaction with mono‐and dialdehydes. The structure of these model compounds and polymers was confirmed by elemental analyses, IR and electronic spectra. The model compounds are also characterized by their mass spectra, and in the case of sufficient solubility by 1H NMR spectroscopy too. The electrical conductivities of all compounds and polymers and the thermooxidative degradation of the polymers were investigated.
Effects of annealing of elongated nylon 6
Authors: Ikeda Susumu , Matsuda Kazuo
Published: April 2003

The shrinkage of extended nylon 6 was studied by the methods of isothermal annealing and tempering. The shrinkage was discussed in comparison with that of amorphous polymer solids in the glass transition region. It was found that the annealing below the melting temperature of crystalline polymer solids showed two effects: one was the shrinkage of samples tracing the quasi‐equilibrium states and the other was the relaxation process stabilizing the strain. The rate of shrinkage of nylon 6 during tempering became large at the two temperature ranges, i. e., one was the glass transition region and the other the neighborhood of elongation temperatures above 100°C. Because of the effect of relaxation stabilizing the strain, the rate of shrinkage during tempering decreased at intermediate temperatures between the two temperature ranges. A stabilizing effect also was found in the fact that γ type crystallites were stabilized during tempering.
A new approach to the theory of rubber elasticity
Authors: Mukherji Barun
Published: April 2003

Current polymer network theories do not explain the experimental behaviour clearly. The use of Gaussian distribution might be the reason of this limitation. The approximation of the distribution of the chain vector by a Gaussian function implies non‐vanishing probability for chains at full extension and beyond. In the stress‐strain relation, the first derivative with respect to strain of the logarithm of the distribution function is involved. For Gaussian distribution this derivative deviates very much from that of the actual distribution especially at higher extensions. The properties of the said derivatives for different distributions were examined. It is observed that the use of the Langevin distribution might be more realistic. A new approach is suggested on this basis. The tensile force per unit cross section, τ, for an extension ratio α at constant volume has the form

where an average chain contributes a length L in each of the three mutually perpendicular directions and contains n equivalent free links of length l each. The expression contains no unknown parameter. This equation has great similarity with the empirical Mooney‐equation and gives much better agreement with experimental results.
Comments on an estimation of the rigidity of a macromolecular chain from hydrodynamic data by means of graphic methods
Authors: Kovár̂ Josef , Fortelný Ivan , Bohdanecký Miloslav
Published: April 2003

It is demonstrated, by means of an analysis of theoretical relationships, that evaluation of hydrodynamic data by uncritically applied extrapolation methods, especially if the only criterion of their applicability consists in the linearity of graphic plots, may lead to incorrect conclusions about the rigidity of the polymer chain. A simple procedure is suggested for the characterization of the quality of hydrodynamic data from the viewpoint of determination of the rigidity of a polymer chain.
Functional metal‐porphyrazine derivatives and their polymers, 2. Synthesis and properties of polyimides containing metal‐phthalocyanines
Authors: Shirai Hirofusa , Kobayashi Kesayoshi , Takemae Yoshitaka , Suzuki Akira , Hirabaru Okikazu , Hojo Nobumasa
Published: April 2003

A novel class of polyimides (14) containing Mt(II)‐phthalocyanine rings has been synthesized by the solution condensation in N‐methyl‐2‐pyrrolidone (NMP) of Mt(II)‐[2,9or10(or2, 16or17)bis(3,4‐dicarboxybenzoyl)]phthalocyanine dianhydride (Mt(II)‐dahPc; Mt(II)=Co(II), Ni(II) and Cu(II); (2–4)) with aromatic diamines such as 4,4′‐methylenebis(aniline), followed by thermal imidization in vacuo at 200°C. The polyamides obtained were soluble in NMP and hexamethylphosphoric triamide, having inherent viscosities up to 0,7 dl·g−1. The polyimides were stable up to 350°C, and showed room temperature‐dc‐resistivities in the range of 1011 to 106 Ω·cm.
Calorimetric studies in the helix‐coil transition of poly(amino acid)s in methanol‐water solvent mixtures
Authors: Baba Yoshihiro , Kagemoto Akihiro , Fujishiro Ryoichi
Published: April 2003

By combining the heat of dilution of solutions of poly(L‐lysine) and poly(L‐ornithine) in methanol‐water solvent mixtures with the corresponding heat of mixing of the methanol‐water system, the integrated heats of the coil‐helix transition of poly(L‐lysine) and poly(L‐ornithine) were estimated to be about −3,1 and −4,4 kJ per mole of the constitutional repeating unit, respectively. The solvent composition at which the transition occurs was determined to be about 0,85 and 0,94 for the volume fraction of methanol for poly(L‐lysine) and poly(L‐ornithine), respectively. These results are in good agreement with those obtained by optical rotatory dispersion.
Relaxation properties of linear polyethers: Dielectric behavior of poly(oxyhexamethylene)
Authors: Riande E.
Published: April 2003

The dielectric relaxation behavior of poly(oxyhexamethylene) was studied over the temperature range 50 to −56°C at different frequencies lying in the interval 102 to 105 Hz. A single absorption and dispersion is observed in the region of −40°C which shows the same frequency temperature location as the α mechanical relaxation. Therefore, it is postulated that the mechanisms that give rise to both the dielectric and mechanical processes are of the same nature. The α relaxation is associated with micro‐Brownian motions in the amorphous phase of the polymer and seems to shift to higher temperature as the number of methylene groups in the repeating unit increases. From the analysis on the flexibility of polyethers, including the limiting case of polyethylene, it is concluded that the lower limit for the glass transition of polyethylene should be in the vicinity of −80°C.
Anionic polymerization of 2‐Oxo‐1,3,2λ5‐dioxaphosphorinane. Thermodynamics
Authors: Kałużyński Krzysztof , Penczek Stanisław
Published: April 2003

Thermodynamics of the polymerization of 2‐oxo‐1,3,2λ5‐dioxaphosphorinane in bulk initiated by sodium metal is described. Enthalpy (ΔHp = 6,28 ± 0,84 kJ · mol−1) and entropy (ΔS = 19,25 ± 2,51 J · mol−1 · K−1) of polymerization were evaluated from the temperature dependence of the equilibrium nomomer concentration determined directly by 31P{1H} NMR. The results are compared with those obtained previously for the polymerization of other 2‐alkoxy‐2‐oxo‐1,3,2λ5‐dioxaphosphorinanes.
Some observations on complexes of a cobalt phthalocyanine with poly(vinylamine) and their catalytic activity in the autoxidation of thiols
Authors: Schutten Jan H. , Piet Pieter , German Anton L.
Published: April 2003

Complexes of the tetrasodium salt of cobalt(II)‐tetrasulfophthalocyanine and poly(vinylamine) were applied as bifunctional catalysts for the autoxidation of thiols to disulfides. Optical and catalytic experiments gave supporting evidence to the hypothesis, that the isolation of cobalt centers and the catalytic activity can be promoted by increasing the relative amount of polymeric base. It appeared that the specific catalytic activity of the polymeric catalysts depends on the number average degree of polymerization (P̄n) of the applied polymer samples. In particular at relatively high cobalt content, samples with comparatively low P̄n give more protection against aggregation of cobalt sites (i.e. inactivation) and, therefore, effect a higher specific catalytic activity. A statistical calculation, suitable to determine the distribution of cobalt sites over the polymeric coils, supports the interpretation of the experimental data.
Time resolved light scattering measurements on the disentanglement diffusion following the degradation of poly(phenyl vinyl ketone)
Authors: Tagawa S. , Schnabel W.
Published: April 2003

Poly(phenyl vinyl ketone) was irradiated in 1,4‐dioxane solutions with 25 ns flashes of 347, 1 nm light at various incident intensities. The rate of fragment separation following the very rapid rupture of chemical bonds in the main chains was measured. For this purpose the decrease of the intensity of light scattered by the polymer solution (LSI) was monitored as a function of time after the flash at various scattering angles. It was found that the lifetime of the LSI change τ(LSI) decreased with increasing scattering angle. This is due to the fact that main chain breaks are statistically distributed over all molecules and along the chains thus causing the generation of small and large fragments. The larger fragments which move at smaller speed contribute stronger to the LSI at low scattering angles than the small ones. It was, furthermore, found that τ(LSI) is independent of Zs, the average number of scissions per initial macromolecule, if the fragment size exceeds a critical value which was estimated as being of the order of 103 base units in this case. τ(LSI) decreased with increasing Zs steadily if the average size of fragments was smaller than the critical value. This was evidenced both by measuring τ(LSI) as a function of the initial molecular weight and of the scattering angle. In conclusion: intramolecular interaction is determining disentanglement motions if the chain length exceeds a critical value. At shorter chain lengths pure translational motions become rate determining.