bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal polymerization of dihydro‐exo‐dicyclopentadienyl acrylate
Authors: Hatano Akira , Iwase Yoshiyuki , Toda Yoshihisa 
Published: April 2003

AbstractThe thermal polymerization of dihydro‐exo‐dicyclopentadienyl acrylate (DDA) (tricyclo[5.2.1.02.6]dec‐3‐en‐9‐yl acrylate) was carried out under nitrogen in the absence of any initiator to investigate the kinetics and mechanism for it. The polymerization rate was found to follow the equation: Rp=k[DDA]1.6. The rate was nearly the same as those obtained for the polymerization of other alkyl acrylates. The overall activation energy for the polymerization was determined to be 57,3 kJ/mol (13,7 kcal/mol). The kinetic data and the data obtained by spin trapping technique during the polymerization showed that the double bond of the acryl group was polymerized much faster than that of the cyclopentene ring to form the straight chain polymer and that the double bond of the cyclopentene ring began to polymerize to a small extent, at a stage where most of acryl groups were polymerized, to give some crosslinking structures.
Mechanism of the polymerization of hexamethylcyclotrisiloxane (D3) in the presence of a strong protonic acid
Authors: Chojnowski Julian , Wilczek Lech 
Published: April 2003

AbstractThe polymerization of hexamethylcyclotrisiloxane (D3) was studied in methylene chloride solution in the presence of trifluoromethanesulfonic acid as catalyst. The reaction occurs mostly by addition of monomer to the ends of growing molecular chains. However, an important role is played by cleavage of a siloxane bond in the monomer by acid or water as well as by reverse processes of silanol and/or +ylester end group condensation to siloxane linkages. The latter account for the formation of large amounts of cyclic products and for the coupling of linear chain fragments. They are also responsible for the regeneration of the catalyst leading to establishment of stationary concentrations of reactive species in the polymerization system.The involvement of the above mentioned processes of condensation and siloxane bond cleavage contributes to a dramatic change in kinetics of the polymerization with introduction of water into the reaction system. In particular, the polymerization when carried out without water addition shows three interconnected features: 1 Strong acceleration of the rate with addition of small amounts of water to the system. 2 An apparent negative value of the activation energy. 3 Increase of the rate with decreasing initial concentration of the monomer. Above a certain level of water content the polymerization rate is only slightly dependent on the concentration of water. The energy of activation is 50 kJ/mol and the reaction is of 1st order in monomer, internally as well as externally.
Inverse problems in polymer characterization: Direct analysis of polydispersity with photon correlation spectroscopy
Authors: Provencher Stephen W. 
Published: April 2003

AbstractA method is presented for inverting the Fredholm integral equations of the first kind that arise in many experimental determinations of molecular weight distributions of high polymers. The well known problems of instability and nonuniqueness are minimized by constraining the distribution to be the smoothest nonnegative one that is consistent with the data. Analyses of simulated photon correlation spectroscopy data show that good accuracy can be obtained for unimodal distributions and fair accuracy for certain bimodal ones, provided that systematic errors are kept below the random noise level. The method is completely automatic in that no initial estimate or prior information about the distribution is needed. However, if there happens to be a priori knowledge that the distribution is unimodal or that it is bimodal, constraining the distribution accordingly can further improve the stability and accuracy.
Properties of blends of poly(ethylene oxide) samples with different molecular weight: Kinetics of crystallization from melt
Authors: Cimmino Sossio , Greco Roberto , Martuscelli Ezio , Silvestre Clara 
Published: April 2003

AbstractThe crystallization kinetics of binary blends of samples of poly(ethylene oxide) with different molecular weights, namely 2000, 20 000, and 197000 has been investigated by means of polarized light microscopy in order to establish the dependence of the kinetic parameters upon the composition. The temperature and composition dependence of the growth rates of spherulites in thin films of supercooled melt has been analyzed by means of the theoretical expressions given by Hoffman and Lauritzen. The experimental results indicate that some kinetic and thermodynamic quantities such as the rate of crystallization, the equilibrium melting temperature, the free energy of formation of a nucleus of critical size, and the surface free energy of folding are strongly dependent upon the composition of the blends.
Melting behavior of syndiotacticity‐rich poly(vinyl alcohol)‐water gel
Authors: Matsuzawa Shuji , Yamaura Kazuo , Maeda Ryuzo , Ogasawara Kenji 
Published: April 2003

AbstractThe melting temperatures of a syndiotacticity‐rich poly(vinyl alcohol)‐water gel were measured for concentrations below 70g.dm‐3. In the gel chilled at a temperature below about 15°C the melting point first decreased monotonously then sharply in a jump and again monotonously with decreasing concentration, whereas in the gel chilled above 20°C the melting point decreased monotonously through‐out. The change of the shear modulus of a gel chilled at 0°C with the rise of temperature from 0°C to the melting point was also measured. Initially the shear modulus decreased, then increased to a maximum value, and at last decreased towards the melting temperature, whereas a gel chilled at 40°C kept an almost constant value during heating from 40°C up to a high temperature and then decreased with further rise of temperature. The turbidity of dilute solutions chilled at 0°C passed a minimum and maximum with the rise of temperature in accord with the minimum and maximum of the shear modulus. It is thus concluded that in the gel chilled at temperatures below 15°C the junctions grow to some extent with the rise of temperature.
Oxidation of tertiary amines with N‐chloronylon 66
Authors: Sato Tsuneyuki , Schulz Rolf C. 
Published: April 2003

AbstractOxidation of tertiary amines with N‐chloronylon 66 (NCN) was investigated in several organic solvents. NCN was found to oxidize N,N‐dimethylaniline (DMA) at room temperature to give N‐methylaniline with 15–50% yield, depending on the solvents used. Oxidation of N,N‐dimethylbenzylamine (DMBA) gave benzaldehyde with 15–30% yield and a small amount of N‐methylbenzylamine. A mechanism was discussed. For comparison, N‐chlorosuccinimide, a low molecular N‐chloro‐compound, was also used for oxidation of DMA and DMBA.
Gpc study of thermo‐oxidative degradation of poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Hudec Pavel , Sláma Zdeněk , Štěpánková Helena 
Published: April 2003

AbstractThe method of gel permeation chromatography was used to study the structural changes of poly(2,6‐dimethyl‐1,4‐phenylene oxide) in the course of thermooxidative degradation. During the degradation two principal processes occur: random scission and crosslinking. The latter process leads to the formation of insoluble fractions. The reaction rates and activation energies of both processes have been determined. The mechanism of degradation as well as the influence of some additives is discussed on the basis of experimental data.
Pharmakologisch‐aktive polymere, 18. Körperverteilung und ausscheidungsverhalten von monomerem und polymerem sulfadiazinacrylamid
Authors: Hofmann Volker , Ringsdorf Helmut , Schaumlöffel Erich 
Published: April 2003

AbstractSulfadiazinacrylamid was absorbed after oral and intraperitoneal application in rats to a high extent; the absorption from the intraperitoneum was retarded. Glucose treatment delayed the absorption after both application forms. At comparatively high renal and enteral excretion rates the biological half life time of the monomer was estimated to 8 h. A tumouraffinity was not found but there were indications for a preferred storage in the RES.Poly[sulfadiazinacrylamide] was absorbed after intraperitoneal injection to a clear extent, where at the beginning of the treatment under simultaneous glucose load the absorption was delayed. 24 h after injection higher concentrations in metabolic organs and those of the RES were established. After oral application of the polymer an effective resorption was excluded. The elimination of the intraperitoneally injected polymer happened at negligibly low dose rates; after oral application the elimination process was finished within 24 h after treatment of the test animals. The polymer showed no tumouraffinity.
Azoinitiatoren, 9.Synthese und pfropfung azogruppenhaltiger polycarbonate
Authors: Kerber Robert , Gerum Johannes , Nuyken Oskar 
Published: April 2003

AbstractPolycarbonate 3 was synthesized by copolymerisation of 4‐(p‐hydroxyphenylisopropyl)phenol with [3,5‐Bis(hydroxymethyl)phenylazo]‐methylmalonodinitrile (2a). This azo groups containing polycarbonate was employed as initiator for graft copolymerisations. The content of azo functions in the resulting copolymers was determined by 1H NMR, microanalysis, and DSC‐measurements, and Mn by vapor pressure osmometry. Grafting was carried out with styrene in 1,4‐dioxane and the resulting products were characterized by IR, 1H NMR, HPLC, and vapor pressure osmometry.
Haloaldehyde polymers, 12. Preparation and polymerization of bromodifluoroacetaldehyde
Authors: Campbell R. W. , Vogl O. 
Published: April 2003

AbstractBromodifluoroacetaldehyde (5) was prepared from methyl bromodifluoroacetate (4) by reduction with lithium aluminium hydride. 4 was in turn prepared by bromination of chlorotrifluoroethylene (1) and treatment of the resulting 1,2‐dibromo‐1‐chlorotrifluoroethane (2) with fuming H2SO4 and HgO. 5, properly purified, could be polymerized with anionic and cationic initiators to poly[oxy‐2‐(bromodifluoro)ethylidene] (12). Certain initiators produce partially or entirely amorphous soluble 12 of relatively low molecular weight. Most polymers, however, are insoluble, crystalline, and presumably isotactic. Thermal vacuum degradation of the polymers 12 gave monomer 5 in essentially quantitative yield. The thermal stability of polymers can significantly be improved by endcapping or treating with agents which replace unstable end groups. The ceiling temperature of the polymerization of 5 was determined to be +48°C. 5 was copolymerized with trichloroacetaldehyde with cationic or anionic initiators to copolymers containing predominantly units of 5. 5 could also be copolymerized with phenyl isocyanate to a polymer containing oxycarbamido linkages.
Self‐diffusion of benzene in the presence of macromolecules
Authors: Reimschüssel Władysław , Hawlicka Ewa 
Published: April 2003

AbstractTo measure the self‐diffusion coefficients the open‐end capillary method was used. The solvent self‐diffusion coefficients in benzene solutions of polystyrene and poly(methyl methacrylate) were determined in a concentration range up to 30g·dm−3 and in dependence of temperature. It was observed that in very dilute polymer solutions (for polymer concentration smaller than 4g·dm−3) the benzene self‐diffusion coefficients were higher than the one of pure benzene. The hypothesis is given that this effect is due to the change of benzene structure in the presence of macromolecules.
Synthesis and study of poly(8‐hydroxyquinoline‐7,5‐diylethylene)
Authors: Patel B. S. , Choxi G. S. , Patel S. R. 
Published: April 2003

AbstractPoly(8‐hydroxyquinoline‐7,5‐diylethylene) (3) was prepared both by Friedel‐Craft's condensation of 8‐hydroxyquinoline (1) with 1,2‐dichloroethane (2) in the presence of anhydrous aluminium chloride and by condensation of 1 with ethylene glycol in the presence of an acid catalyst. The polymer samples were found to be insoluble in acetic acid, sulfuric acid, conc. hydrochloric acid, or formic acid. They were characterized by IR and UV spectra. Their molecular weights were determined by conductometric titration in pyridine. Viscometric studies were carried out in formic acid and in glacial acetic acid at 35°C. Solutions of the polymer samples in formic acid showed normal behaviour, whereas those in glacial acetic acid showed an abnormal behaviour. Various empirical relations were applied to correlate the viscosity data of solutions in glacial acetic acid with the appropriate concentration function. Aqueous acetic acid and simple electrolytes were used as solvents to supress the abnormal behaviour.
Polarographische Untersuchungen an monomeren und polymeren N‐Chlorcarbonamiden
Authors: Günster Engelbert , Schulz Rolf C. 
Published: April 2003

AbstractThe polarographic reduction of low molecular and high molecular N‐chlorocarboxamides at the dropping mercury electrode proceeds in two one‐electron‐transfer steps, which are highly irreversible. In the case of the low molecular models 1 and 2 the reaction is diffusion‐controlled, whereas in the case of the poly(N‐chloroamide) 3 the reaction is adsorption‐controlled. Reduction of several poly(N‐chloroamide)s shows always two reduction waves with a distance of 0,5 V. There is, however, no relation between the polyamide‐type and the position of the half‐wave potentials. The polarographic reduction can be used as an analytical method for quantitative determination of N‐chlorocarboxamide groups in polymers.
Über die Kinetik der Reaktion von Hexamethylendiisocyanat mit 2‐ethyl‐1,3‐hexandiol in verschiedenen Lösungsmitteln
Authors: Hager Wilhelm , Ueberreiter Kurt 
Published: April 2003

AbstractThe kinetics of the polyaddition reaction of hexamethylenediisocyanate with 2‐ethyl‐1,3‐hexanediol were investigated in various aprotic solvents with zero dipole moment. The reactions were followed by means of IR‐spectroscopy. The reaction is of 2nd order. Rate constants depend on the dielectric constants of solvents. Energy of activation does not depend on the nature of the solvent, its value for the first isocyanate group is 28,97 kJ/mol and 17,79 kJ/mol for the second one. It is surprising that the consecutive reaction of the second isocyanate group is faster than that of the first one, if the diol is 2‐ethyl‐1,3‐hexanediol. This has not been found before. It could be shown that in the addition reaction of the same isocyanate with 2‐methyl‐2,4‐pentanediol the reactivity of the second isocyanate group is much smaller than that of the first one, as has been found with other dioles investigated until now.
Ring opening in the polymerization of propylene oxide by the initiator systems aluminium isopropoxide or aluminium isopropoxide/zinc chloride (1:1) and the microstructure of the resulting polymers
Authors: Jedlinski Zbigniew , Dworak Andrzej , Bero Maciej 
Published: April 2003

Abstract2‐Methyloxirane (propylene oxide) was polymerized by aluminium isopropoxide [Al(OiPr)3] and by the initiator system Al(OiPr)3/zinc chloride (1:1). The microstructure of the resulting polymers was investigated by 13C NMR spectroscopy. The polymer obtained with Al(OiPr)3 alone was found to contain head‐to‐tail and head‐to‐head linkages in the chain, indicating an oxirane ring opening in both α‐ and β‐positions. The polymerization by the aluminium isopropoxide/zinc chloride initiator system led to the formation of a crystalline, highly isotactic fraction and to an amorphous, almost atactic fraction of the polymer with head‐to‐tail linkages only.
Metachromasia of pinacyanol chloride induced by synthetic polyanions
Authors: Pal M. K. , Ghosh Bijan Kumar 
Published: April 2003

AbstractThe metachromasia of the cyanine dye pinacyanol chloride sharply depends on the nature of the polyanions the dye interacts with. The metachromatic spectra of the dye induced by polymethacrylate (only at polymer/dye mole ratios P/D>3), polyacrylate and poly(vinyl sulfate) are broad and multiple‐banded; whereas the spectra are sharp and single‐banded with poly(methacrylic acid) and polystyrenesulfonate as the chromotropes. Poly(methacrylic acid) and polystyrenesulfonate form compounds with the dye with 2:1 stoichiometry, whereas the polyanion‐dye complexes with polyacrylate and poly(vinyl sulfate) as polyanions have 1:1 stoichiometry. This observed difference in the metachromasia of this dye has been discussed in terms of the differences in stoichiometry, flexibility and conformation of the polyanion chains.
On the copolymerization of acrylonitrile with styrene in the presence of Lewis acid, 3. Photoinitiated copolymerization
Authors: Bartoň Jaroslav , Werner Peter , Capek Ignác 
Published: April 2003

AbstractThe rate of the acrylonitrile (AN)‐styrene (St) copolymerization (Rp) photoinitiated (λ=365 nm) by the StANZnCl2 complex at 30°C is proportional to the square root of the intensity of radiation. The limiting viscosity number [η] of alternating copolymers increases with the intensity of radiation. The 1/[η] vs. Rp relationship for the StAN copolymers is similar as has been found for the initiation of copolymerization by thermal decomposition of 2,2‐azoisobutyronitrile. Provided benzophenone combined with 2‐propanol is used as a photosensitizer, the rate of the StAN copolymerization in acetone—at constant concentrations of both comonomers, zinc chloride, and benzophenone—decreases with 2‐propanol concentration in the reaction mixture. If benzophenone alone (e.g. without 2‐propanol) is used as a photosensitizer under equal conditions, the observed values of the rate of copolymerization are lower in comparison with the system where the ternary molecular complex is empolyed as a photosensitizer. Moreover, Rp decreases with increasing concentration of benzophenone in the system. These findings are interpreted as a result of the termination reactions of ketyl radicals (hydroxydiphenylmethyl radicals) with macroradicals of copolymer.
13C NMR‐Spektroskopische Untersuchungen über den Einfluß anorganischer Salze auf die Solvatation von N,N′‐Dibenzoyl‐m‐phenylendiamin in N,N‐Dimethylacetamid
Authors: von Goldammer Eberhard , Schollmeyer Eckhard , Hirt Peter , Aichele Wilfried , Herlinger Heinz 
Published: April 2003

AbstractChanges of the solvation sphere of N,N′‐dibenzoyl‐m‐phenlyenediamine (as a model substance for aromatic polyamides) in N,N′‐dimethylacetamide caused by electrolytes such as LiCl, LiBr or BeCl2 were studied by 13C NMR chemical shift measurements. The observed variations of the chemical shift data were interpreted by a stronger interaction of the solvent molecules with the carbonamide group. The relation of the carbonyl and the amide group interaction with the solvent or the solvated cations depends on the kind of electrolyte. It is not possible to correlate the obtained results with the influence of these electrolytes upon the molecular weight of the aromatic polyamides prepared in N,N′‐dimethylacetamide. Therefore some possible explanations are discussed.
Properties of solution grown crystals of aliphatic polyesters with variable amount of double bonds along the chain
Authors: Crispino Luigi , Maglio Giovanni , Martuscelli Ezio , Palumbo Rosario , Pracella Mariano 
Published: April 2003

AbstractIn order to elucidate the relations between morphological habits, thermal behaviour and chemical structure of polymers, aliphatic polyesters with variable amount of trans‐double bonds along the backbone chain were crystallized from dilute solutions in 1‐propanol and 1‐butanol. The crystals were studied with electron microscopy, differential scanning calorimetry, and wide angle X‐ray diffraction. The morphology of solution grown single crystals and some thermodynamic quantities such as the equilibrium dissolution and melting temperature and the enthalpy and entropy of fusion are influenced by the percentage of unsaturated comonomer. The thermal behaviour and the X‐ray diffraction of these crystals suggest that saturated and unsaturated repeating units are able to cocrystallize.
Application of spin trapping technique to radical polymerization, 16. Photo‐decomposition of diphenyl disulfide and initiation mechanism: Evaluation of relative reactivities of vinyl monomers toward phenylthio radical
Authors: Sato Tsuneyuki , Abe Masao , Otsu Takayuki 
Published: April 2003

AbstractTo clarify the initiation process in radical polymerizations with diphenyl disulfide (DPDS) as initiator, spin trapping technique was applied to the reaction of vinyl monomers with the phenylthio radical (1), which was produced by photolysis of DPDS. 2‐Methyl‐2‐nitrosopropane (BNO) was used as a spin trapping agent. When DPDS was photo‐decomposed in benzene in the presence of BNO radical 1 was trapped as the corresponding aminyl oxide radical 2, which is unstable at room temperature. The photolysis of DPDS in vinyl monomers of type H2CCXY, however, gave only aminyl oxide radicals resulting from their propagating radicals C6H5SCH2C˙XY. Contrary to the results obtained with tert‐butoxyl radicals, radical 1 was found to undergo exclusively addition reaction to the double bond of the α‐methyl‐substituted monomers, such as methyl methacrylate or methacrylonitrile, with no hydrogen‐abstraction reaction from their α‐methyl group. Relative rates of the initiation reactions of vinyl monomers with radical 1 were also determined by spin trapping technique. It was found that the reactivities of vinyl monomers toward radical 1 are controlled by both polar and resonance effects.
Dilute solution properties of methyl methacrylate/acrylonitrile random copolymers, 1. Mark‐Houwink relation
Authors: Kashyap A. K. , Kalpagam V. 
Published: April 2003

AbstractStudies on the dilute solution properties of methyl methacrylate/acrylonitrile random copolymers of 0,566 mole fraction (m. f.) of acrylonitrile (AN), designated as MA3 and of 0,657 m. f. of AN, designated as MA4 reveal that the Mark‐Houwink exponent values a for MA3 lie in the range 0,6 to 0,8 and for MA4 in the range 0,8 to 1,1 in the solvents studied, viz. acetonitrile (MeCN), 2‐butanone (MEK), N,N‐dimethylformamide (DMF) and γ‐butyrolactone (γ‐BL) at the temperatures 30°C, 45°C and 60°C. Such large values of a suggest that these copolymer chains are highly extended in these solvents. The decrease of [η] with an increase in temperature also supports the above conclusion that these are very good solvents.
Gelchromatographische refraktionierung, 1. Ein verfahren zur korrektur von gelchromatogrammen
Authors: Berger K. C. 
Published: April 2003

AbstractA mathematical method is proposed for calculating the gel chromatogram w(v0) after correction with the instrument spreading function D(v, v0) and for calculating D(v,v0) using experimental data on the basis, that a gel chromatographic polymer fraction of the chromatogram e(v) is collected and injected again. The chromatogram of this fraction c(v) can be described by the integral equation:

where v0 is the elution volume and v1 is the volume at which the fraction is collected. The solution of this equation simultaneously with Tung's equation by way of minimizing is suggested.
Über Polyarylenalkenylene und Polyheteroarylenalkenylene, 10. Synthesen und Charakterisierung von Poly‐(3,5‐dimethylthiazolo [4,5‐f]benzthiazoldiium‐2,6‐diylvinylenarylenvinylen)en und einigen Modellverbindungen
Authors: Koßmehl Gerhard , Bocionek Peter , Manecke Georg 
Published: April 2003

AbstractFrom 2,3,5,6‐tetramethylthiazolo [4,5‐f]benzothiazoldiium diperchlorate (2) and dialdehydes of the benzene and the thiophene series the corresponding poly(3,5‐dimethylthiazolo[4,5‐f]benzothiazoldiium‐2,6‐diylvinylenarylenevinylene diperchlorate)s 6a–c were synthesized via Knoevenagel condensation. Analogous reactions with comparable monoaldehydes gave a series of model compounds 4a–c. The structures were confirmed by elemental analyses and by IR and electronic spectra. In addition, the model compounds were characterized by their 1H NMR and mass spectra. The electrical dark conductivities of all substances and the thermooxidative degradation of the polymers were studied.