bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the influence of stabilizers, metals, and peroxides on the thermo‐oxidative degradation of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene)
Authors: Sláma Zdeněk , Mayer Josef
Published: April 2003

The authors have studied the influence of some stabilizers, trace amounts of cupric and ferric compounds, and peroxides on the thermo‐oxidative degradation of poly(oxy‐2,6‐dimethyl‐1,4‐phenylene). It was found that phenolic antioxidants, didodecyl 3,3′‐thiodipropionate, and phosphorous acid esters do not exhibit a stabilizing effect. 2‐Benzimidazolethiol, 2‐benzothiazolethiol, and hexamethylphosphoric triamide were found to be retardation agents. Based on these results a mechanism of the degradation process is proposed.
Photopolymerization of methyl methacrylate in bulk and in pyridine diluted systems with pyridine‐sulfur dioxide complex alone and in combination with benzoyl peroxide as photoinitiators
Authors: Ghosh Premamoy , Biswas Samir
Published: April 2003

It was found that the Py‐SO2 complex (4–140 mmol·1−1) initiates the photopolymerization of methyl methacrylate (MMA) in bulk at 40°C, the initiator exponent, k/kt, and the monomer exponent being 0,30, 1,27·10−2 1·mol−1·s−1, and 1,00, respectively. The radical generation is followed by an in‐situ initiator‐monomer complexation reaction. The kinetics of the photopolymerization of MMA were also studied using the (Py‐SO2)‐complex (0,01–0,35 mol·1−1) in redox combination with benzoyl peroxide (BZ2O2) (2 − 110 mmol·1−1) as initiator in the presence of variable concentrations of pyridine (1 − 7 mol·1−1). The initiation depends on the concentrations of all the reactants in the system, and the reaction order with respect to either component of the redox pair is equal to 0,5 or reasonably less than 0,5, depending on whether or not the initiating component in question is present in the system in excess compared to its counterpart in the redox combination. Variable monomer exponents, largely dependent on [BZ2O2], characterize the redox photopolymerization process. The monomer exponent value, unity at [BZ2O2] = 0, progressively decreases with increasing [BZ2O2] (non‐ideal kinetics). The rate enhancing effect of the solvent pyridine is more prominent at higher [BZ2O2]. The kinetic nonidealities in each case were further analyzed and interpreted in terms of (a) primary radical termination and (b) degradative initiator transfer. Relative effects of the variation of the level of dilution with pyridine were also analyzed.
The influence of interaction between constituent blocks on conformation of the ABA type 2‐hydroxyethyl methacrylate/styrene block copolymer in a solvent mixture
Authors: Ikemi Masahisa , Watanabe Tatsuya , Okano Teruo , Shinohara Isao
Published: April 2003

The ABA type block copolymer of 2‐hydroxyethyl methacrylate (HEMA) and styrene was synthesized and the influence of the interaction between constituent blocks on the conformational change of the block copolymer was investigated in mixtures of DMF and 1,4‐dioxane which are selective solvents for poly(HEMA) and polystyrene, respectively. The intrinsic viscosity [η] of the mixture from the parent homopolymers of the block copolymer was compared with the value calculated on assuming lack of interaction between unlike segments. The [η] value at 15°C was found to agree with the calculated value despite of incompatibility between dissimilar segments. On the contrary, the [η] value at 30°C deviated positively from the theoretical value, especially in N,N‐dimethylformamide (DMF) or 1,4‐dioxane‐rich solvents, indicating that hetero contact between unlike segments at elevated temperature results in an increase of the average hydrodynamic volume because of repulsive interaction. The molecular expansion was found to become large with an enhancement of incompatibility. The same kind of transition versus temperature was observed in the intrinsic viscosity curve of the block copolymer, suggesting that hetero contacts between dissimilar segments occur at elevated temperature and that enhancement of solvent selectivity results in a conformational change of the block copolymer. A further increase of the solvent selectivity toward the polystyrene blocks was found to lead to intermolecular association of the block copolymer through aggregation of the poly(HEMA) side blocks.
Eine neue methode zur ermittlung kinetischer und kalorischer daten einer radikalischen copolymerisation, 2. Verbesserte auswertungsmethode am beispiel des systems 2‐hydroxyethylmethacrylat/methylmethacrylat
Authors: Fink Johannes Karl
Published: April 2003

The monomer reactivity ratios and the ratio of the rate constants of termination in the 2‐hydroxyethyl methacrylate/methyl methacrylate system were measured by differential thermal analysis. The data for the monomer reactivity ratios agree well with data calculated from the Q‐e scheme.
Polymerization reactivity of styrene complexes composed of maleic anhydride, p‐chloranil or 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone
Authors: Iwatsuki Shouji , Itoh Takahito , Hiraiwa Akihiko
Published: April 2003

Terpolymerizations of styrene (St)/p‐chloranil (PCA)/maleic anhydride (MAnh), St/2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ)/MAnh, and St/DDQ/PCA systems were studied, in order to compare the reactivities as acceptor monomers among MAnh, PCA, and DDQ. These terpolymerizations were treated by the complex mechanism. The modified and real monomer reactivity ratios of the complexes in these systems were obtained as rI(KI/KII) (PCA‐St) = 1,60 and rII(KII/KI) (MAnh‐St) = 0,10, rI(PCA‐St) = 3,55 and rII(MAnh‐St) = 0,045, rI(KI/KII) (DDQ‐St) = 50 and rII(KII/KI) (MAnh‐St) = 0,01, rI(DDQ‐St) = 132 and rII(MAnh‐St) = 0,0038, and rI(KI/KII) (DDQ‐St) = 200 and rII(KII/KI) (PCA‐St) = 0,001, rI(DDQ‐St) = 238 and rII(PCA‐St) = 0,0008, respectively. The reactivity of these St complexes was concluded to be controlled primarily by the polarity of the acceptor monomers.
Reactivity of growing radical in the copolymerization of styrenes with oxygen in the presence of cobalt complex
Authors: Nukui Masahiro , Ohkatsu Yasukazu , Tsuruta Teiji
Published: April 2003

Copolymerizations of a styrene homologue with oxygen were carried out in the presence of a Co(II) (Schiff‐base) complex having a chiral ligand. The metal complex showed a retarding effect on the rate of oxygen absorption in the reaction due to its interaction with growing radicals. Main product was almost an equimolar copolymer of monomer and oxygen, in the case of styrene and α‐methylstyrene. On the other hand, trans epoxide as well as a copolymer having many ether units were formed in the reaction of β‐methylstyrene. The presence of the cobalt complex increased the yield of epoxide and induced asymmetry in the epoxide.
Aggregation of poly(methacrylic acid)‐poly(ethylene oxide) complex in aqueous medium
Authors: Ohno Hiroyuki , Matsuda Hiro , Tsuchida Eishun
Published: April 2003

It is known that poly(methacrylic acid) and poly(ethylene oxide) interact with each other through hydrogen bonds and form polymer complexes in an aqueous medium. The initially formed polymer complexes were considered to exist in a semi‐stable state, and they aggregated through desolvation and hydrophobic interaction. A successive aggregation of polymer complexes was observed following the rapid initial complexation. The aggregation was affected by some chemical factors e.g., polymer concentration, temperature, pH and so on. These effects were measured as the changes of the molecular shape by means of laser‐light scattering, turbidity measurements, and scanning electron microscopy. It was observed that lower pH and higher temperature made the aggregation faster within such experimental conditions as pH 2–7, 20–50°C. The aggregates were nearly spherical with almost the same diameter (200 nm), and spontaneously grew larger with time.
New catalysts for the oxidative polymerization of 2,6‐dimethylphenol, 4. The crystal and molecular structure of tetrakis(tetrabutylammonium) hexakis(2,2‐dicyano‐1,1‐ethenedithiolato)octacuprate(i), tetrakis(tetrabutylammonium) hexakis‐(1,2‐dicyano‐1,2‐ethenedithiolato)octacuprate(i), and hexakis[copper(i)‐n,n‐diethylthiocarbamate]
Authors: Dietrich Hans , Storck Winfried , Manecke Georg
Published: April 2003

The X‐ray determination of the crystal structures shows that the dicyanoethenedithiolatocopper(I) complexes [N(C4H9)4]4[Cu8(S2CC(CN)2)6] (1) and [N(C4H9)4]4[Cu8(S(CN)CC(CN)S)6] (2) contain cube‐shaped Cu8‐clusters, whereas the Cu(I)‐N,N‐(diethyl)thiocarbamate complex (3) contains a Cu6‐octahedron in its centre. A common feature of the three complexes is the coordination of each copper atom by three donor atoms having suitable empty orbitals for back‐donation. This results in flat pyramidal arrangements with the basal plane of the three donor atoms being outside the cluster. All clusters deviate significantly from their ideal symmetry. In complex 2 the Cu8‐cube is tetragonally elongated and the CuCu‐distances are in general much larger (3,20 and 3,70 Å, respectively) than in other comparable complexes. Moreover, its anions are fitted into cages of a pseudocubic hydrophobic matrix formed by the tetrabutylammonium cations. It is concluded that is is the bonding within the coordination pyramids of the copper atoms which stabilizes the clusters, whereas the bonding within the clusters seems to be of comparably small importance.
Télomérisation de l'isobutylène
Authors: Taha Mohammed , Rigal Gérard , Piétrasanta Yves , Platzer Nicole , Sudres Pierre , Raynal Serge
Published: April 2003

The telomerization of isobutene was investigated using redox catalysis, free radical, and particularly cationic initiation. The influence of the initiator on the degree of polymerization and the structure of the telomers was studied. Redox and free radical telomerization with CCl4 and CCl3Br were found to permit synthesis and identification of the monoadduct structure. Cationic telomerization gives regular structure compounds and the molecular weights are higher than those obtained by other methods of telomerization.
Syntheses and characterization of random copolymers of aspartic acid with lactic acid and glycolic acid
Authors: Jain Ganput L. , Ray Alok R.
Published: April 2003

Random copolymerization of aspartic acid with lactic acid and with glycolic acid was carried out using o‐phosphoric acid as catalyst.
Recherche de télomères à activité pharmacologique potentielle, 3. Préparation et toxicologie de supports télomères à fonctions hydroxyles
Authors: Bauduin Gérard , Bondon Daniel , Martel Jacques , Pietrasanta Yves , Pucci Bernard , Serrano Jean‐Jacques , Francois Colette
Published: April 2003

Several telomers of vinyl alcohol with chloroform and diethyl phosphonate were prepared. Their DPn were measured by several analytical methods (elemental analysis, NMR spectroscopy, viscosimetry). Their small molecular size, their good water‐solubility, and their very low acute toxicity allow to use them as drug‐carriers in pharmacological applications.
Reaktive Träger auf der Basis von Polyethylenimin zur Immobilisierung von Enzymen
Authors: Manecke Georg , Heydolph Sabine
Published: April 2003

Reactive slightly basic carriers with isothiocyanato and azido groups, which are able to bind enzymes covalently, could be obtained by reaction of crosslinked and uncrosslinked poly‐(ethyleneimine) with 4‐nitrophenyl isothiocyanate, 4‐nitrophenyl isocyanate, or ethyl chloroacetate, respectively, and subsequent reactions. The binding ability of the carriers for papain, trypsin, α‐chymotrypsin, and urease in dependence of the content of reactive groups and in the case of urease as function of the amount of offered enzyme was investigated. To characterize the immobilized enzymes some properties as enzymatic activity, storage stability, and stability after repeated application were determined.
Thermodynamic studies on poly(a) · poly(u) duplex‐dye systems
Authors: Tanaka Shigeyuki , Baba Yoshihiro , Kagemoto Akihiro , Fujishiro Ryoichi
Published: April 2003

The interaction between poly(A) · poly(U) duplex and dyes (proflavine (PF) and 9‐aminoacridine (9‐AA)) was studied by means of the heat of mixing. From the results, thermodynamic quantities of poly(A) · poly(U) duplex‐dye systems for the intercalation process were estimated. The free energy change for the poly(A) · poly(U) duplex‐(PF) system is smaller than that for the poly(A) · poly(U) duplex‐(9‐AA) system, indicating that PF intercalated into poly(A) · poly(U) duplex is more stable than the intercalated 9‐AA. This conclusion is based on the absolute value of the heat of interaction between PF and poly(A) · poly(U) duplex being larger than that between 9‐AA and the poly(A) · poly(U) duplex.
Kinetics of the anionic polymerization of tert‐butyl methacrylate in tetrahydrofuran
Authors: Müller Axel H. E.
Published: April 2003

The anionic polymerization of tert‐butyl methacrylate (TBMA) in tetrahydrofuran, using Na+ and Cs+ as counterions proceeds without side reactions even at room temperature. The resulting molecular weight distributions are nearly monodisperse (Mw/Mn ⩽ 1,01). The rate constants for the propagation of ion pairs were measured in the range from + 15 to −100°C. The Arrhenius plots are linear, but different for the two counterions, resulting in the following numerical values for the frequency exponent A and the activation energy Ea:

A = 8,5 and Ea = 7,2 kcal/mol = 30 kJ/mol for Na+;

A = 9,5 and Ea = 5,6 kcal/mol = 23 kJ/mol for Cs+.

The difference between the counterions, which is in contrast to the polymerization of methyl methacrylate (MMA), as well as the lower rate constants are not due to the steric factor of the tert‐butyl group but to its positive inductive effect which influences the structure of the propagating macroion pair by decreasing its reactivity. The relative reactivities of the PMMA and PTBMA ion pairs towards MMA and TBMA are estimated.
Polymers containing enzymatically degradable bonds, 4. Preliminary experiments in vivo
Authors: Kopeček Jindřich , Cífková Irena , Rejmanová Pavla , Strohalm Jiří , Obereigner Blahoslav , Ulbrich Karel
Published: April 2003

Copolymers of N‐(2‐hydroxypropyl)methacrylamide containing oligopeptidic sequences either in side chains or as part of crosslinks were prepared. These polymers were applied intravenously to rats, and spectrophotometric analysis (oligopeptidic side chains) or gel permeation chromatography of urine (oligopeptidic crosslinks) have shown that both types of polymers are cleavable in vivo.
Polymere schiff‐basen‐chelate und ihre vorstufen, 3. Synthese polymer gebundener N3O2‐chelate durch N‐alkylierung niedermolekularer schiff‐basen
Authors: Aeissen Henning , Wöhrle Dieter
Published: April 2003

N‐Alkylation of low molcular N3O2‐ligands (2a, b) with several chloromethylated polystyrenes (1a–e) leads to covalently polymer bound Schiff's base ligands (3a–f), which react with Co2+ to polymer bound N3O2 chelates (10a–f). A second route to 3c starts from 1b and the N3‐ligand 5 over the polymer diamine 7. The corresponding low molecular compounds were also prepared.
Ritter's reaction of poly(acrylonitrile)
Authors: Janout Václav , Čefelín Pavel
Published: April 2003

The course of Ritter's reaction of atactic poly(acrylonitrile) with N‐hydroxymethylamides of acetic, benzoic and benzenesulfonic acids and with N‐hydroxymethylimides of succinic, phthalic and o‐sulfobenzoic acids were examined in tetramethylene sulfone under conditions where benzyl alcohol, isopropyl alcohol and triphenylmethanol appear as nonreactive. The reaction systems have a stronger tendency towards crosslinking than that exhibited under comparable conditions by solutions of poly(N‐benzamidomethylacrylamide), poly(N‐phthalimidomethylacrylamide) and poly(N‐o‐sulfobenzamidomethylacrylamide) prepared as reference standards by the solution polymerization of the N‐substituted acrylamides in methanol with dibenzoyl peroxide as initiator.
The structure of poly(N‐vinylcarbazole) obtained with cationic initiators and electron acceptors as catalysts
Authors: Kawamura Tokiji , Matsuzaki Kei
Published: April 2003

Poly(N‐vinylcarbazole)s, [poly(l‐(N‐carbazolyl)ethylene)s], (PVCz's) were prepared under various polymerization conditions. The stereoregularities were estimated by means of 13C NMR spectroscopy. Although the stereoregularity of the polymers obtained by BF3O(C2H5)2 was hardly changed by the polymerization temperature, it changed with the solvent polarity from an isotactic‐rich configuration in toluene and CH2Cl2 to a syndiotactic‐rich configuration in nitrobenzene. The 13C NMR spectra of the polymers obtained by organic electron acceptors, support the conclusion that the polymerization by tetracyanoethylene, p‐bromanil, 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone, and tetrachlorophthalic anhydride proceed by a cationic mechanism. In the polymerization of N‐vinylcarbazole (VCz) with maleic anhydride as an electron acceptor, a small amount of copolymer was obtained together with the homopolymer of VCz. Although the structure of the homopolymers is the same as that of the radically obtained polymer, it is considered that the polymer is formed by a cationic mechanism. The polymerizations of VCz by inorganic compounds, such as ferric nitrate, cupric nitrate, cupric bromide, etc., as catalysts are cationic.
Polymerization of lactams, 40. Acceleration of the anionic polymerization of 2‐pyrrolidone
Authors: Patil Vishvanath S. , Roda Jan , Králíček Jaroslav
Published: April 2003

The effect of transient cooling of the polymerization mixture on the anionic polymerization of 2‐pyrrolidone initiated with potassium 2‐pyrrolidonate (2‐oxo‐1‐pyrrolidinylpotassium) prepared in situ and activated with N‐acetyl‐2‐pyrrolidone was investigated. It was found that an increase in conversion and molecular weight is controlled by the time interval between the onset of polymerization and transient cooling of the mixture, unlike an isothermal arrangement of the experiment. The possible mechanism by which the polymerization process is affected is discussed.
Copolymers of 2‐acrylamido‐2‐methylpropanesulfonic acid and aromatic vinyl compounds as potential media for photosensitized electron transfer reactions
Authors: Morishima Yotaro , Itoh Yoshihiro , Nozakura Shun‐ichi
Published: April 2003

In an expectation as potential media for photosensitized electron transfer reactions, polymers carrying both strong electrolytic and hydrophobic segments were prepared by the copolymerization of 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) and styrene. The AMPS segments were found to have a remarkable power to solubilize the hydrophobic segments into water, i.e., even a copolymer with a styrene mole fraction of 0,72 is still soluble in water. Salt effect on the reduced viscosity, broadening of NMR spectra in D2O, and enhanced excimer fluorescence of styryl groups in aqueous solution indicated a pronounced hydrophobic interaction of a number of styryl groups along the chain in the copolymer with high styrene content. 8‐Anilinonaphthalene‐1‐sulfonic acid, 1,6‐diphenyl‐1,3,5‐hexatriene, and a cyanine dye were used as fluorescent probes for the hydrophobic microdomains. The results suggested that the microdomains are highly hydrophobic in nature but less capable to solubilize the fluorescent probes than the surfactant micelles. An electron microscopic image of the copolymer was also discussed as a supporting evidence for the presence of microdomains.
Elementarprozesse löslicher ziegler‐katalysatoren. Polymerisationskinetische analyse und mathematische modellierung im system Cp2TiPropylCl/AlEtCl2/ethylen
Authors: Fink Gerhard , Zoller Welf
Published: April 2003

This paper deals with the kinetics of the polymerization of ethylene catalysed by the soluble Ziegler‐catalyst Cp2TiPropylCl/AlEtCl2. By means of a special method it was possible to study the kinetics of the initial instationary homogeneous part of the polymerization. The dependences of the initial rates on the catalyst components prove that the polymerization active species is formed in two successive very dynamic equilibria. The primary complex equilibrium is entirely located on the right hand side, whereas the second equilibrium depends considerably on the ratio of the catalyst components and is shifted on the active species side only at very high Al/Ti ratios. Because of this location of the two successive equilibria the dependence of the polymerization velocity vp on the charged Al concentration (that is, the Al isotherm) has to show a sigmoidal curve course in the inital part, which experimentally is confirmed exactly. Finally, this extensive kinetical analysis leads to the complete reaction scheme of the polyreaction and by mathematical modelling to the quantitative calculation and description of the experimental curves and dependences (e.g., Al‐isotherm).
Zur copolymerisation von ethylen und α‐olefinen mit ziegler‐katalysatoren
Authors: Böhm Ludwig L.
Published: April 2003

Starting with four reaction equations which are at least necessary to describe the copolymerization of two monomers, equations for the kinetics and the molecular weight regulation with and without hydrogen are derived. The equations are used to evaluate the results of the copolymerization of ethylene and 1‐butene. The numerical values of the reactivity ratios r differ by approximately 3 orders of magnitude, but do not depend on whether the molecular weight is regulated by hydrogen or not. The rate of polymerization is scarcely influenced even by great amounts of 1‐butene. It depends nearly completely on the concentration of ethylene. On the other hand the comonomer enormously influences the average molecular weight of the copolymer. This influence increases with hydrogen content.
Polychelates derived from 4,4′‐(4,4′‐biphenylylenebisazo)di(salicylaldehyde oxime)
Authors: Rana Arjun K. , Shah Navnit R. , Patil Manak S. , Karampurwala Asger M. , Shah Jayant R.
Published: April 2003

Polychelates of Ni(II), Co(II), Cu(II), Zn(II), and Mn(II) were synthesized from bis 4,4′‐(4,4′‐biphenylenebisazo)di(salicylaldehyde oxime) and metal chlorides. All the chelates are dark in colour and insoluble in common organic solvents. Their most probable structures were determined by visible reflectance spectroscopy and magnetic measurements in conjunction with thermogravimetric and IR measurements. Elemental analyses indicate a ligand: metal ratio of 1:1 and the association of water molecules with the central metal. The decomposition temperatures of the polychelates decrease in the following order: Zn(II) > Co(II) > Ni(II) > Mn(II) > Cu(II).
Recherche de télomères à activité pharmacologique potentielle, 4. Réactions sur les télomères de l'alcool vinylique
Authors: Bauduin Gérard , Bessière Jean‐Marie , Bondon Daniel , Martel Jacques , Piétrasanta Yves
Published: April 2003

Chlorides of carboxylic acids were grafted on telomers of vinyl alcohol. The yields of grafting were improved by increasing the temperature and the concentration of the reactants. In the range investigated, they do not depend on the DPn of the telomers, nor on the stoichiometric rates of the reactants. Therefore, the grafting rates are directly related to the initial conditions of the reaction. Modification of the telomers by treatment with ethylene oxide provides more soluble substances, but it does not affect the behaviour of the telomers in grafting reactions. Grafting of 1‐(p‐chlorobenzoyl)‐5‐methoxy‐2‐methyl‐3‐indolacetic acid (9) (indomethacin), an antiinflammatory drug, leads to potentially pharmacologically active telomers.
Functional monomers and polymers, 92. Synthetic application of the dehydrating and desulfhydrylating activity of chloropyrimidine derivatives, particularly of the immobilized derivative
Authors: Kondo Koichi , Hyodo Kenji , Murakami Mikio , Takemoto Kiichi
Published: April 2003

Chloropyrimidine derivatives were found to be useful as active dehydrating and desulfhydrylating reagents for the preparation of carbodiimides, isothiocyanates, esters, lactones, amides, or nitriles. Particularly a polystyrene‐bound reagent was quite useful also due to the advantage of isolating the products easily by using a simple filtration technique. The following decreasing order of reactivity was found: 4‐chloro‐2‐pyrimidone bound to polystyrene (poly{1‐[4‐(4‐chloro‐2‐oxo‐1,2‐dihydro‐1‐pyrimidinyl)phenyl]ethylene}) (5a) ≃ 4‐chloro‐1‐cyclohexyl‐2‐pyrimidone (3a) > 2,4,6‐trichloropyrimidine (2a) > 2,4‐dichloropyrimidine (1a) ≫ 9‐benzyl‐6‐chloropurine (4a). The reactivities are related to the structure, and an enhanced ease of lactim‐lactam tautomerism in the products is suggested as driving force of the reaction.
Dunkel‐ und photoleitung polymerer cyaninfarbstoffe
Authors: Koßmehl Gerhard , Bocionek Peter
Published: April 2003

An equipment for measuring the photoconduction of polymeric material is described comprehensively. The electrical dark conductivities (σ ≤ 2,5 · 10−9 Ω−1 · cm−1) and the photoconduction (Iphot ≤ 2,0 · 10−10 A) were studied for polymeric cyanines and corresponding model compounds. Photoconduction was measured as a function of temperature, current, wavelength, and intensity of the used light.
Graft copolymerization of methyl methacrylate on chlorinated natural rubber, 2. Initiation by tetrakis(trialkylphosphite)nickel
Authors: Nogues Pierre , Dawans François , Maréchal Ernest
Published: April 2003

The kinetics of the graft copolymerization of methyl methacrylate (MMA) initiated by the system chlorinated natural rubber (CR)/Ni[P(OC6H5)3]4 was studied. The orders in monomer and in catalyst were found to be 1 and 1,5, respectively, corresponding to a free radical mechanism. In most cases, the homopolymer was extracted by an experimental technique described in Part 1 of this series. The extent of homopolymer formation increases with increasing reaction temperature and with the [Ni]/[Cl] ratio. Experimental conditions are described avoiding homopolymer formation. The graft copolymerization initiated by the system CR/Ni[P(OEt)3]4 was studied at different temperatures. At 35°C, this initiator was found to be very active, but copolymerization stops after 10% conversion.
Photoinitiation, 7. Terpolymerization of the system acrylonitrile/maleic anhydride/styrene
Authors: Capek Ignác , Bartoň Jaroslav
Published: April 2003

The photoinitiated (at wavelength λ = 365 nm) terpolymerization of acrylonitrile, maleic anhydride and styrene in the presence and/or absence of additives such as ZnCl2 or N,N‐dimethylaniline (DMA) in acetone was studied, and the relative reactivities R of maleic anhydride and acrylonitrile towards a styryl radical were determined. In the presence of ZnCl2 and/or DMA, the relative reactivities R are by about 40% lower than the value of R (= 13,3 ± 2,1) for the terpolymerization system without additives.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 9. Synthèse de polybutadiènes: étude des microstructures
Authors: Brosse Jean‐Claude , Bonnier Maryvonne , Legeay Gilbert
Published: April 2003

Butadiene polymerization with hydrogen peroxide resulted in the simultaneous formation of oligomers, polymers, and high polymers. Analyses of their microstructures showed that oligomers have a higher content of 1,2‐structures (28%) than the polymers (22%). The nature of the chain ends was determined with low molecular weight compounds. The content of 1,2‐units is distinctly higher in the oligomers, which shows that initiation takes place preferably in 1,2‐ and propagation in 1,4‐position. Besides hydroxyl end groups, other functional groups were detected in small quantities in the low molecular weight products: aldehydes, ketones, acids, hydroperoxides, and epoxides. These functions result from secondary reactions such as transfer, initiation, or termination reactions with alcohol releasing radicals.
Wholly aromatic polyamides containing bridged biphenylylene groups, 2. Copolyamides
Authors: Kaneda Takaho , Ishikawa Seiji , Daimon Hiroshi , Katsura Toshio , Ueda Mashiro , Oda Kunio , Horio Masao
Published: April 2003

A number of wholly aromatic copolyamides containing bridged biphenylylene groups were synthesized from a mixture of aromatic diamines and terephthaloyl chloride, on one hand, and from a mixture of aromatic diacid dichlorides and 1,4‐phenylenediamine, on the other hand. Each mixture of diamines and of diacid dichlorides was constituted of a phenylene derivative and a bridged biphenylylene derivative. The copolyamides synthesized were dissolved in high concentration sulfuric acid and spun into fibers. The fibers spun showed fairly high tensile strengths and high initial moduli, but annealing caused further increase in strength and modulus. All the copolyamides studied had very high thermal resistances.
Practical aspects to the use of indirect fourier transformation methods
Authors: Müller Karl , Glatter Otto
Published: April 2003

Practical hints for the application of the indirect Fourier transformation method are given. In detail there are discussed the problems of stabilization of the least squares routine, the estimation of the maximum dimension of the particles, the choice of an appropriate number of the spline functions, the combination of scattering functions measured with different primary beam geometry, standard deviation and error propagation of the solution functions, influence of the interparticle interference effect and background scattering on the results, determination of the radius of gyration and the scattering intensity at zero angle and finally the possibility of simulation of measuring curves starting with model bodies is described. It is attempted to demonstrate the advantages of indirect Fourier transformation on hand of several practical examples.
Influence of expansion of polymer molecules in solution on non‐newtonian flow behavior
Authors: Ito Yoshio , Shiina Shoji , Tokue Ikuo
Published: April 2003

Non‐Newtonian viscosity could be explained by the Graessely entanglement viscosity theory modified by a frictional viscosity for moderately concentrated solutions of polydimethyIsiloxanes over a range of shear rates from lower to upper‐Newtonian flow. The expansion of a polymer molecule was kept under control by use of solvents with different dissolving powers of the polymer. The result shows that only the frictional viscosity is strongly related to the degree of expansion of a polymer molecule in solution and that Graessley's plots are independent of that. Extrapolation of the frictional viscosity versus concentration curves to 100wt.‐% show a common value of 0,09 Pa·s in spite of different degrees of expansion of the polymer molecules in solution. This common value was equal to the viscosity value for melt polymer with the same molecular weight as a polymer segment. It is concluded that the frictional viscosity is caused by solvent‐solvent, solvent‐polymer segment, and segment‐segment interactions.
Aliphatic‐aromatic polyamide‐imides from diisocyanates, 2. Study of the influence of the reaction conditions on polymer structure
Authors: de la Campa José G. , de Abajo Javier , Nieto José L.
Published: April 2003

The polycondensation of 4,4′‐methylenediphenylisocyanate and 6‐(4‐carboxyphthalimido)‐hexanoic acid was studied under different conditions in order to establish the influence of factors such as temperature, catalyst, stoichiometric disbalance, and addition order of reactants on the molecular weight and the chemical composition of the final polyamide‐imide. All these factors proved to influence the extent of possible side reactions that lead to undersirable functions, the main ones being urea functions that locate within the polymer backbone. Other side‐reactions proposed to explain the formation of acylureas or biurets did not take place in appreciable extent since these functions could not be detected by NMR spectroscopy. Therefore, particular emphasis was made to prevent the formation of urea by changing the polycondensation conditions. A first attempt to clarify the regularity degree of the polymers (amounts of head to tail and head to head addition) by 1H NMR spectroscopy was also made.
Effect of metal laurates on polymerization of methyl methacrylate in benzene
Authors: Theerthalingam T. , Kothandaraman H. , Santappa M.
Published: April 2003

Polymerization of methyl methacrylate initiated by laurates of Fe(III), Co(III) and Mn(III) in benzene medium at 60°C was studied. The polymerization was found to be free radical in nature. The rate of polymerization was proportional to the square of the concentration of the monomer and inversely proportional to the concentration of the solvent. The initiator exponent was found to be 0,23. The rate parameters for the system were evaluated. The reactivity of the different metal laurates was compared. A kinetic scheme is proposed in the light of the experimental results involving initiation of the polymerization by a monomer‐initiator complex and termination by a initiator‐solvent complex.
Syntheses and infrared‐spectroscopic studies of homo‐oligomeric peptides derived from γ‐benzyl‐L‐glutamate
Authors: Ozaki Takuo , Shoji Akira , Furukawa Makoto
Published: April 2003

A series of homo‐oligomeric peptides derived fromγ‐benzyl‐L‐glutamate, Nps‐[L‐Glu‐(OBzl)] n+m−OBzl (4(n, m)) (n + m = 2 to 12, 15, 16, 18, 21, and 24), were synthesized for the first time by the DCC‐ONSu method using and activated easter. The identification and conformation of these peptides in cast films were investigated successfully by IR spectroscopy. It was found that the formation of the β‐structure begins with the tetrapeptide, and that of the α‐helix in the range from the hexapeptide to octapeptide. There is some evidence for small quantities of other conformational nuclei which may coexist as preferred conformations in peptides between the hexa‐ and decapetides. These effect cannot be attributed to sample purity since they could be shown to be analytically pure.
Etude par spectroscopie infrarouge d'alcanes ramifiés et de polymères modèles — application à la determination du taux de ramifications dans les polyéthylènes basse densité
Authors: Frêche Patrick , Grenier‐Loustalot Marie‐Florence , Cascoin Alain
Published: April 2003

The absorption band at 1378 cm−1 was used for the quantitative determination of branching in polyethylene. Using various models with different alkyl groups (12‐alkyltriacosanes, 11,20‐dialkyltriacontances, alkylcyclohexanes, homopolymers), new absorption coefficients, depending on their branching, were obtained. The degrees of branching of a series of copolymers deriving from α‐olefins (15 compounds) determined by infrared spectroscopy with the new coefficients and by 13C NMR spectroscopy were compared.
Induced circular dichroism of polypeptide‐dye systems in a mesophase
Authors: Sato Yukio , Hatano Masahiro
Published: April 2003

The interaction of polypeptides with dyes in a lyotropic mesophase, consisting of Tween 80 (monooleate of the ether of sorbitan with 4 mol of polyethyleneglycol) and water, was studied, and the arrangement of dyes in the mesophase was discussed on the basis of the spectral change of circular dichroism under an electric field. The following results were observed. (1) The addition of a polypeptide to the mesophase considerably influenced the helical pitch of the mesophase. (2) In the mesophase the complexes of polypeptides with dyes were formed more easily than in aqueous solution. (3) When this mesophase was used as an orientation solvent under the electric field, the observed variation of circular dichroism bands could be used for an assignment of each band polarization. Thus, in the acidic region, acridine orange molecules are bound in such a manner that their long‐axes of molecular plane form a right‐handed super‐helix around the core of the α‐helix of poly(α,L‐glutamic acid). In the alkaline region, the poly(α,L‐glutamic acid)‐acridine orange complex cannot take a helical form, even when the mole ratio of polypeptide residues to dye molecules is ≈ 1.
Synthesis and properties of copolyimides, 2. Preparation and properties of polypyromellitimides from p‐phenylenediamine and m‐phenylenediamine
Authors: Babu Gaddam Nana , Samant Shubha
Published: April 2003

Copolymers were prepared by reacting a prepolymer consisting of an anhydride terminated polymeric acid from pyromellitic anhydride and a diamine (p‐ or m‐phenylenediamine), with the second diamine. The resulting polymeric acids were converted into polyimides by thermal cyclodehydration. The corresponding random copolyimides were prepared by a conventional procedure and their properties were compared with those of three step copolyimides of similar composition.
Terpolymérisation acrylonitrile/styrène/acrylate de méthyle, 3. Etude du mécanisme de la copolymérisation en emulsion
Authors: Guillot Jean , Guerrero Leonardo Rios
Published: April 2003

Emulsion copolymerization appears to be very suitable for mechanistic investigations in emulsion polymerization. A study of the emulsion copolymerization under various conditions (batch, semi‐continuous, composition controlled reactor) of the styrene (S)/acrylonitrile (A) system is presented, which may have model character due to the very different monomer solubilities both in water and in their polymers. Comparison of copolymer composition with monomer mixture composition in the various phases (determine by gas chromatography analysis after the emulsion has been centrifuged) confirms that the monomer/polymer particles are the main loci of polymerization. The monomier / water ratio and the amount of emulsifier sodium dodecylsulfate influence the polymerization rate (Rp) as well as the particle size (D̄p). The existance of a monomer droplet phase seems also to be determinant for many features of such as a copolymerization as, e. g., the evolution of Rp, D̄p, number of particles (Np) etc. In addition, in a batch process, the composition drift versus conversion modified the monomer solubilities within the particles, the emulsifier adsorption, the particle growth which appeared to reach a limiting size, mainly due to electrostatic hindrance. It is also observed, Whatever may be the emulsion polymerization process, that Rp is not proportional towards Np, but towards dNp/dt; this might be related to the particle growth rate. A. mechanism is derived, based on experimental data and thermodynamic considerations, which allows to take into account molecular interactions (χ), coplymer composition, Dp, interfacial tension (γ), and above all, the actual monomer feed composition within the polymerization loci, as the copolymerization proceeds.
Spacer effect in the template polycondensation of nucleotide analogs with diamines
Authors: Nakagawa Hiroshi , Muraki Michiro , Miura Yozo , Kinoshita Masayoshi
Published: April 2003

The template effect of polymers containing the adenine residue, 6, bound to a polystyrene backbone via a spacer group, on the polycondensation of active esters of thymine, 1, and theophylline, 2, with piperazine was studied in pyridine/methylene chloride or DMF. Template polymers accelerated the polycondensation of 1 with diamines by a factor of 5–20, but the polycondensation of 2 with piperazine showed no considerable template effect.
Synthèse de compoisés photoréticulables, 4. Estérification de l'acide acrylique sur les télomères de l'acrylate d'hydroxy‐2 éthyle
Authors: Boutevin Bernard , Maliszewicz Marc , Piétrasanta Yves
Published: April 2003

Several telomers were prepared by redox catalysis from 2‐hydroxyethyl acrylate (1) and telogens such as carbon tetrachloride, methyl trichloroacetate, 1, 1, 1‐trichlorotrifluoroethane, and 2,4,4,4‐tetrachloro‐2‐methylbutyric acid (2d), as well as block‐cotelomers from 1 and a telomer 4 prepared from chlorotrifluoroethylene and carbon tetrachloride. Polyols (3a–d and 5) with two to twenty primary hydroxyl groups were obtained. They were esterified with acrylic acid, to obtain new photosensitive compositions. (6a–d).
Zur alterung von wäßrigen polyacrylamid‐lösungen
Authors: Mächtle Walter
Published: April 2003

For 62 days the aging behaviour of diluted solutions of an extremely pure, linear, noncharged polyacrylamide with Mw = 8400 000 g/mol in water was examined. The solutions were stored in a sterile surrounding at 298 K. The following quantities, all of which give information about the molecular weight or the dimension of the macromolecules, were measured: the intrinsic viscosity [η], the sedimentation cofficient s0, the translational diffusion coefficient (Dt)z, the molecular weight, Mw, and the radius of gyration, Rz. Within the accuracy of the measurements all these quantities remained constant. That means, in contrast to other authors, that we could not observe any aging effect in our solutions. It seems that polyacrylamide dissolved in water shows a behavior like a coil molecule in a thermodynamically good solution.
Some solution properties of poly(ethyl methacrylate)
Authors: Olayemi Julius Y.
Published: April 2003

The viscosity of dilute solutions of poly(ethyl methacrylate) in each of methyl acetate, ethyl acetate and isobutyl acetate was studied over the temperature range of 20–65°C. The intrinsic viscosity either remained approximately constant or slightly decreased over the temperature range because of conformational changes. The temperature ranges of conformational change were 40–50°C, 40–50°C, and 35–55°C for the polymer in methyl acetate, ethyl acetate, and isobutyl acetate, respectively. The Huggins constant was also influenced by the type of solvent and by temperature changes, especially over the temperature range in which conformational changes took place. Conformational changes of poly(ethyl methacrylate) in aliphatic organic esters as solvents are believed to be due to changes in the interaction between the polymer segments and the solvent.
Anomalous diffusion of dextran in DMF‐water mixed solvent system: A case of preferential solvation of the dextran molecule?
Authors: Amu Thomas C.
Published: April 2003

Anomalous diffusional behaviour — not evident for the carbohydrate oligomers glucose, sucrose, and raffinose — was observed for dextran in the DMF‐H2O mixed solvent system at 25°C. The plot of interdiffusion coefficients (D0) for the dextran against the mole fraction of water (X) in the DMF‐H2O mixtures shows a discontinuity with a maximum in D0 at X = 0,85. Plots of intrinsic viscosities [η], for two higher molecular weight dextrans, against X also show transitions at X = 0,85. The anomalous behaviour of the dextrans at this solvent composition is discussed in terms of a solvent induced conformational transition of the dextran molecule.
Biozide polymere, 6. Synthese und polymerisation von acryl‐ und methacrylsäurederivaten des 3‐amino‐1,2,4‐triazols
Authors: Bauer Hans‐Jürgen , Hartmann Manfred , Wermann Kurt
Published: April 2003

Preparation and characterization (by IR and 1H NMR spectroscopy) of isomeric methacrylic acid and acrylic acid derivatives of the herbicide 3‐amino‐1,2,4‐traizole are described. Their radical polymerization and copolymerization with styrene or methyl methacrylate give polymers containing the herbicide moiety as pendant groups bound via acyl groups at the amino group or at the ring nitrogen. The reactivity ratios were determined for the isomeric methacrylic compounds.
Télomères monofonctionnels du chlorure de vinyle, 4. Synthèse et caractérisation par catalyse rédox
Authors: Boutevin Bernard , Piétrasanta Yves , Taha Mohamed
Published: April 2003

Monofunctional telomers of vinyl chloride (1) were synthesized by two ways. In the first one, the telomers resulting from the reaction of 1 with carbon tetrachloride were used as telogenic agents to react with allyl acetate leading to a monoadduct. In the second one, monofunctional telogens were used in a redox catalyzed reaction with 1. Trichloroacetic acid and its esters (2b–d) were applied as telogens. The theoretical maximum yields and the number average degrees of polymerization at these yields were calculated and compared with the experimental results.
On the initiation sites of poly(vinyl chloride) dehydrochlorination, 1. Kinetic view of the problem
Authors: Valko L. , Šimon P. , Kellö V.
Published: April 2003

The kinetics of the thermal dehydrochlorination of PVC was investigated with respect to the initiation mechanism of the hydrogen chloride chain elimination. The constant rate of dehydrochlorination in the early stages of the dehydrochlorination process is explained by an intra‐chain initiation mechanism which is a consequence of a constant amount of active sites (structural irregularities) incorporated in the chains. After an initial period, dehydrochlorination is occurring in a random way, and (or) by an inter‐chain dehydrochlorination mechanism initiated by a “sudden polarization” effect between the postulated zwitterion and a meanwhile unreacted CH2CHCl group.
Thermodynamic and hydrodynamic properties of aliphatic polyesters, 1. Solubility, intrinsic viscosity, and molecular weight of poly(β‐propiolactone)
Authors: Rosenvasser Daniel , Casas Aurelio Sagrario , Figini Ruben V.
Published: April 2003

Absolute molecular weight, intrinsic viscosity, refractive index increment, refractive index, partial specific density, solubility and molecular weight distribution of poly(β‐propiolactone) is studied. The measured molecular weights range from 40000 up to nearly 1000000. The relationship between intrinsic viscosity and molecular weight [η] = 0,0259 · M ml/g (CHCl3, 30,0°C) shows that the polymer molecule is a linear flexible chain.
Étude calorimétrique des interactions polyéthylène/liquide, 1. Interface présentant un angle de contact
Authors: Blanc Raymond , Sage Daniel , Berticat Philippe
Published: April 2003

A technique is described for the measurement of the heat of immersion for polyethylene with a 2 . 10−3 J accuracy. For the studied systems, the heat of mixing is positive and due to solubility of the liquid in the amorphous phase of the polymer. The dissolved fraction is estimated from the heat of mixing according to Flory's theory. Measurement of the surface energy from single crystals indicates that this surface constituted of the folds of the chains behaves as an amorphous phase. Last, the heat of immersion is compared to the value calculated from the contact angle. If the solubility of the liquid is very small, the agreement is good. The case of water is studied: the negative value of the heat of immersion ΔHi proceeds from a change in water structure and a decrease of the enthalpy due to the contact with apolar compounds. This value allows to estimate the solubility of water in polyethylene.
Preparation of 5‐hydroxy‐7‐methoxy‐2,2‐dimethyl‐6‐octyl(and 8‐octyl)‐4‐chromanones and their Properties as UV Absorbers
Authors: Ninagawa Akira , Iseki Takayuki , Matsuda Haruo
Published: April 2003

5‐Hydroxy‐7‐methoxy‐2,2‐dimethyl‐6‐octyl(and 8‐octyl)‐4‐chromanones (2a and 2b) were synthesized via 5,7 dihydroxy‐2,2‐dimethyl‐6‐octyl (and 8‐octyl)‐4‐chromanones (1a and 1b) from phloroglucinol as a starting material. Cyclohexane solutions of 1a, 1b, 2a, and 2b were irradiated. The photostability of 2a and 2b was found to be better than that of 1a and 1b. Poly(vinyl chloride) film containing 6, 7 wt.‐% of 2b was found to be most stable against photooxidation.
The stochastic kinetics of intramolecular reactions in linear polymers
Authors: Raap Ignatius A. , Gröllmann Ulrich
Published: April 2003

This paper deals with the kinetics of reactions of linear flexible macromolecules in solution possessing initially several reactive sites per macromolecule. It is assumed that the reactive sites interact with each other encounter‐controlled and that both intra‐ and intermolecular reactions are possible. On the basis of the theory of stochastic kinetics in microsystems, equations were derived, describing the kinetics of intramolecular reactions as a function of the molecular weight distribution. An important application of this theoretical treatment pertains to the distribution between inter‐ and intramolecular reactions. A demonstration for typical reaction conditions reveals the influence of rate parameters and of the average number of reactive sites per macromolecule r̄(0) on the proportionate distribution expressed by fA = f (r̄(0)); (fA = fraction of intramolecular reactions). This function is only weakly influenced by varying the width parameter β in the case of Schulz‐Zimm molecular weight distributions from β = 1 to → ∞.