bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerizations of chloral, styrene oxide, and methyl methacrylate initiated by the binary system of bis(acetylacetonato)metal(II) and chloral
Authors: Uehara Kaku , Ohashi Yoshiyuki , Tanaka Makoto 
Published: April 2003

AbstractThe binary system of bis(acetylacetonato)metal(II) [M(acac)2] and chloral induced the polymerization of chloral [M = Mn(II), Co(II), Mg(II), and Cu(II)], the ring‐opening polymerization of styrene oxide [M = Co(II) and Mg(II)], and the radical polymerization of methyl methacrylate [M = Mn(II) and Co(II)]. The similar order of activity of M(acac)2 as the catalyst for the polymerization of chloral and for the aldol reaction of chloral with acetylacetone, the deactivation of the catalyst by the introduction of a substituent at the 3‐position of M(acac)2, the presence of saturated β‐diketone at the end of the polymer of chloral and that of styrene oxide, and the visible light spectral data supporting the formation of the β‐ketoalcoholate intermediate in the binary system of Co(acac)2 and chloral are all experimental findings which suggest that M(acac)2 is subject to the aldol addition by chloral at the 3‐position of the chelated acetylacetone and that the resultant β‐ketoalcoholate is a common active species for these polymerizations.
Effect of acid hydrolysis on accessibility of micropores and thermal transition of viscose rayon
Authors: Shinouda H. G. , Moteleb M. M. Abdel 
Published: April 2003

AbstractThe changes in micropores accessible to toluene but inaccessible to decalin taking place during acid hydrolysis of viscose rayon were followed by specific volume measurements. The results show that these changes at the different stages of hydrolysis are of different order and dependent on the hydrolytic conditions. Also, it was found that the decalin molecules, which are larger than toluene molecules, could not follow the gradual disappearance of the thermal transition of viscose rayon with the progress of hydrolysis.
Radical polymerization of methyl methacrylate in the presence of stereoregular poly(methyl methacrylate). VI. Kinetic template effects at higher conversion
Authors: Gons J. , Slagter W. O. , Challa G. 
Published: April 2003

AbstractThe kinetics of radical template polymerization of methyl methacrylate along isotactic poly(methyl methacrylate) as polymer template was studied. It appeared that in addition to a rate increase at low conversions, a second rate enhancement can take place at higher conversion, depending on the nature of the solvent and temperature. While the initial template effect was previously mainly ascribed to hindered segmental motion of propagation chain radicals, the second rate effect is thought to be caused by hindered translational motion of growing chains in a physical network built up during polymerization. The observed second effect is strong in the weakly complexing and network‐promoting solvent toluene, but it is less pronounced in the strongly complexing solvent dimethylformamide. In acetone, also a strongly complexing solvent, the formed stereocomplexes crystallize at low conversions. Due to this crystallization the propagating chains become immobilized, which also results in a strong second rate enhancement. The observed effects are dependent on temperature, but hardly depend on template molecular weight. The influence of the template is further demonstrated by varying its concentration and by the disappearance of the rate enhancement at higher conversion, when the templates become fully covered.
Radiation‐induced oxidation of solid poly(ethylene oxide). II. Mechanism
Authors: Decker Christian 
Published: April 2003

AbstractThe mechanism of γ‐initiated oxidation of solid poly(ethylene oxide) (PEO) has been investigated, and an overall reaction scheme has been developed which accounts for most of the experimental observations. Data are correlated on the basis that the oxidation process is the sum of two reactions that are first‐order and half‐order in rate of initiation. They provide evidence that a significant fraction of the interactions of α‐alkoxyalkylperoxy radicals is nonterminating at ambient temperature and yield free alkoxy radicals that are very subject to β scission. The unimolecular decomposition of secondary peroxy radicals, which has been invoked previously for the oxidation of PEO in solution, is not needed to explain the products of the oxidation of PEO in the solid phase. Approximately 90% of the total oxygen consumption has been accounted for by the observed products of oxidation. The radiochemical yield for backbone radical formation in irradiated PEO was estimated to be 6.5 ± 1.5.
Oligomérisation anionique de l'ethylène. II. Etude des paramètres thermodynamiques
Authors: Magnin Henri , Rodriguez Firmin , Abadie Marc , Schué François 
Published: April 2003

AbstractA kinetic study, as a function of temperature, of ethylene oligomerization by the n‐BuLi–TMEDA complex allowed us to evaluate the thermodynamic parameters (ΔS‡ < −23.7 u.e.) and thus to support a transition state where the ethylene is coordinated to the lithium atom.
Polymerization and properties of optically active α‐(p‐substituted benzenesulfonamido)‐β‐lactones
Authors: Jarm V. , Fleš D. 
Published: April 2003

AbstractOptically active α‐(p‐substituted benzenesulfonamido)‐β‐lactones having as para substituents OMe, Me, H, and Cl were polymerized in bulk, in ethyl acetate solution with triethylamine or betaine, and in dioxane with butyllithium as initiators. The rate of polymerization was followed by the change of specific rotation with time and was decreasing in following order of para substituents: OMe > Me > H > Cl. The relative reactivity in logarithmic form was plotted against Hammett's σ functions showing a linear relationship with reaction constant ρ = −0.57.
Thermosetting acetylene‐terminated polyphenylquinoxalines
Authors: Kovar Robert F. , Ehlers Gerhard F. L. , Arnold Fred E. 
Published: April 2003

AbstractA series of acetylene‐terminated phenylquinoxaline oligomers have been prepared which cure by addition, without the evolution of volatiles. The synthesis utilized the novel terminal acetylene end‐capping reagent, 3‐(3,4‐diaminophenoxy)phenylacetylene. The end‐capped oligomers were soluble (20–30%) in low‐boiling organic solvents and exhibited a high degree of flow at their softening temperatures. Thermal analytical data obtained on the oligomers indicated initial softening in the vicinity of 160°C and a strong polymerization exotherm reaching a maximum at 274°C. Cured samples (8 hr at 280°C) exhibited Tg values of approximately 320°C. Mass spectrometry–thermogravimetric analysis of the polymers demonstrated that no volatiles were emitted during cure, and that decomposition of the resins initiated at 465°C. Synthetic routes to the acetylene terminated phenylquinoxaline oligomers and the end‐capping reagent are discussed as well as the physical properties of the oligomer and cured system.
Mass spectral and pyrolysis/gas‐chromatographic studies of the monomer and polymer of bis(p‐toluenesulfonate) of 2,4‐hexadiyne‐1,6‐diol
Authors: Ghotra J. S. , Stevens G. C. , Bloor D. 
Published: April 2003

AbstractThe thermal degradation of the monomer and polymer of bis(p‐toluenesulfonate) of 2,4‐hexadiyne‐1,6‐diol has been investigated. Decomposition during the latter stages of solid‐state thermal polymerization at 80°C and of 100% polymer at 112°C was observed by mass spectrometry and the decomposition fragments identified. Mechanisms for this low‐temperature degradation are suggested. Pyrolysis of the monomer and polymer between 400 and 1000°C was studied by gas chromatography and mass spectrometry. The principal pyrolysis products are triacetylene and p‐toluenesulfonic acid. The fragmentation routes leading to and derived from these products are discussed.
Polyarylaminophosphazene copolymers
Authors: White Jerry E. , Singler Robert E. 
Published: April 2003

AbstractA series of polyarylaminophosphazene copolymers have been prepared and are described. In each preparation, two arylamines were allowed to competitively react with polydichlorophosphazene, and the substituent ratios of the resulting copolymers, determined by high‐temperature 1H‐NMR spectroscopy, generally reflect expected steric and electronic effects on the relative reactivities of the arylamines studied. The copolymers have intrinsic viscosities of 0.64–1.25 dl/g, glass transition temperatures of 75–104°C, and decomposition temperatures of 220–260°C. These properties, which are comparable to those of polyarylaminophosphazene homopolymers, are discussed in regard to what they may reflect about the structure of the polymers.
Thermal decyanation, a new organic reaction. II
Authors: Haas Howard C. , Moreau Robert D. 
Published: April 2003

AbstractWhen heated in solution at about 160°C, pyridine quaternary salts of bromomalonamides lose 1 mole of cyanic or isocyanic acid almost quantitatively in a manner quite analogous to the decarboxylation of an acid. By DTA and DSC, the crystalline salts are stable up to their melting points (>220°C) at which temperatures concurrent fusion and decyanation processes occur (endotherm); these are immediately followed by an exotherm related to the trimerization of cyanic acid. TGA measurements on the solid salts do not clearly define the loss of 1 mole of cyanic acid because in the solid state, thermal decyanation is accompanied to some extent by other pyrolytic reactions. Preparative methods for quaternizing poly(4‐vinylpyridine) with bromomalonamide are described and two polymeric quaternary salts (33 and 100% substituted) were prepared and analyzed. These polyelectrolytes are water soluble and upon the addition of base the yellow polymeric nitrogen ylids are generated. Infrared spectra on the polymeric quaternary salts and visible spectra on the polymeric ylids are included. The ylid chromophore has an ε = 1800 at λmax = 415 nm. The dilute solution viscosity behavior of these polymers in H2O and in 0.05N KBr is typical of polyelectrolytes. Both polymers in dilute solution show a maximum in ηsp versus pH plots. In water, the viscosity of these polymers decreases with time, and it is proven that this results from a conformational change which accompanies amide hydrolysis rather than polymer backbone degradation. Glass transitions are not detectable by DTA but both polymers show well‐defined trimerization exotherms for cyanic acid starting at 170–175°C. Thus, decyanation of the solid polymeric quaternary salts is more analogous to decyanation of the crystalline quaternarys in solution than as solids. TGA measurements on the polymers show weight losses which are of the correct order of magnitude and in the correct temperature range for monodecyanation. Some data are presented which suggest that perhaps a second mole of cyanic acid is lost at about 250°C. Quaternization of poly(4‐vinylpyridine) with bromomalonamide reduces its gross decomposition temperature from 385°C to about 285–317°C. It is demonstrated how thermal decyanation can be used for the in situ generation of cyanic acid for the modification of organic compounds. The preparation of a partial urethane of poly(vinyl alcohol) using this method is described. We have also shown that aliphatic quaternary salts can be prepared and that they too undergo the decyanation reaction.
γ‐radiation‐initiated polymerization of bulk styrene at high pressure
Authors: Moore P. W. , Ayscough F. W. , Clouston J. G. 
Published: April 2003

AbstractThe polymerization of styrene in bulk at pressures up to 273 MPa and temperatures between 3 and 49°C with the use of γ‐radiation as the initiator has been studied. The polymerization rate and the molecular weight of the polymer increased with increasing pressure; the molecular weight increased at a slightly faster rate. The difference in the rate is a theoretical expectation which has not previously been observed because chain‐transfer reactions obscure the effect in chemically initiated systems. A small but significant retardation of the initiation reaction occurs as the pressure is increased. The results of previous workers are critically reviewed. Chain transfer at 25°C for pressures below 220 MPa is negligible when γ‐radiation is the initiator. The activation energy for bulk polymerization decreased with increasing pressure from 28.1 kJ/mole at 0.1013 MPa to 22.3 kJ/mole at 203 MPa. Volumes of activation at 25°C for 0.1013 < p < 273 MPa were calculated to be Initiation, +4.0 < ΔV < +4.4 cm3/mole; polymerization; −Δ = −20.9 cm3/mole; degree of polymerization; ΔV = −25.3 cm3/mole; propagation/termination; −ΔV = −22.7 cm3/mole.
Electroinitiated polymerization of 2‐vinylnaphthalene
Authors: Phillips D. Colin , Davies D. H. , Smith J. D. B. , Spewock S. 
Published: April 2003

AbstractAs part of a program to extend the range of donor–acceptor‐initiated polymerization processes, the electroinitiation of 2‐vinylnaphthalene in a zinc chloride–sulfolane solution has been studied. Good conversion yields of well‐characterized (NMR, IR, GPC, elemental analysis) poly(vinylnaphthalene) were obtained with the process showing several mechanistic similarities to other donor–acceptor salt electropolymerization systems.
Synthesis of polyamide‐pyrazolones from 2,2′‐disubstituted bis(4‐ethoxymethylene‐5‐oxazolone) and aromatic dihydrazines
Authors: Ueda Mitsuru , Funayama Michio , Imai Yoshio 
Published: April 2003

AbstractA new class of polyamide‐pyrazolones was synthesized by the vinylogous nucleophilic substitution polymerization, which was followed by rearrangement, from 2,2′‐p‐phenylenebis(4‐ethoxymethylene‐5‐oxazolone) and aromatic dihydrazines. Solution polymerization was carried out in polar aprotic solvents under mild conditions to yield polymers having inherent viscosities in the range of 0.5–1.2 quantitatively. The polymer derived from bis(4‐hydrazinophenyl) sulfone was readily soluble in strongly polar solvents, while that from bis(4‐hydrazinophenyl)methane was partially soluble or swelled in these solvents. The polyamide‐pyrazolones which are presumed to contain some intermediate oxazolone structure showed a low level of thermal stability.
Thermal properties and solubility of poly‐1,4,5,8‐naphthalenetetracarboxydiimides containing 1,3,5‐triazine rings
Authors: Takatsuka Ryozo , Unishi Terunobu , Honda Itaru , Kakurai Toshio 
Published: April 2003

AbstractAromatic polyimides were synthesized by polymerization of 1,4,5,8‐naphthalenetetracarboxylic dianhydride and 2‐dialkylamino‐4,6‐dihydrazino‐1,3,5‐triazines by a solution polymerization method followed by cyclodehydration. The polyimides had number‐average molecular weights over 13,000–16,000 or viscosity values of 0.23–0.65 dl/g. The x‐ray diffraction diagram of polyimide I showed a crystal pattern, but the pattern became less pronounced with increasing length of the polymer side chain, and thus polyimide V showed a typical amorphous pattern. Study of the thermal stability of the polyimides by thermogravimetric analysis showed that a steep weight loss occurred in the range 380–410°C. Among the polyimides, I had only poor solubility in organic solvent, while IV and V were soluble even in general organic solvents such as tetrahydrofuran and dioxane.
Studies with model membranes. IX. Evaluation of thermodynamic parameters from the transition state theory of rate processes for electrolyte diffusion through silver chloride parchment‐supported membranes
Authors: Siddiqi Fasih A. , Saksena Santosh K. , Khan Ibadur Rahman 
Published: April 2003

AbstractDiffusion rate of biologically important electrolytes through parchment‐supported silver chloride membrane have been determined by the use of Nernst‐Planck equation at various temperatures taking into account membrane resistance Rm, membrane potential Em, etc. The diffusion rates were found to be primarily dependent upon the difference in the hydration energies of the counterion in the external solution. On the basis of Eisenman‐Sherry theory the diffusion rate sequence of alkali metal cations point towards the weak field strengths of the fixed charge groups. The various thermodynamic parameters, namely, ΔH‡, ΔF‡, and ΔS‡ were evaluated. The values of ΔS‡ found to be negative, indicating that the diffusion is taking place with partial immobilization in the membrane phase. A formal relation between ΔHhydration, ΔFhydration, and ΔShydration of cations with the corresponding values of ΔH‡, ΔF‡, and ΔS‡ for diffusion was also found to exist for the investigated system.
Crystallization of polyterephthalates of bis(4‐hydroxy‐3‐chlorophenyl)‐2,2‐propane
Authors: Korshak V. V. , Babchinitser T. M. , Gorshkov A. P. , Vasnev V. A. , Vasilyev A. V. , Tsvankin D. Ya. , Vinogradova S. V. 
Published: April 2003

AbstractCrystallization of polyterephthalates of bis(4‐hydroxy‐3‐chlorophenyl)‐2,2‐propane synthesized by an acceptor–catalytic polyesterification has been investigated quantitatively. It was found that in a homogeneous medium (in solvents for the polymer) amorphous polymers are formed, while polycondensation in a heterogeneous system (in nonsolvents for the polymer) gives rise to crystalline polyarylates, their degree of crystallization being dependent on synthesis conditions. Secondary treatment of resulting polymers can result in their crystallization and amorphization. Along with molecular weight the physicomechanical properties are significantly affected by the preparation method.
D2‐meta‐carborane‐siloxanes. IV. Synthesis of linear, high molecular weight polymers
Authors: Hedaya E. , Kawakami J. H. , Kopf P. W. , Kwiatkowski G. T. , McNeil D. W. , Owen D. A. , Peters E. N. , Tulis R. W. 
Published: April 2003

AbstractA new facile route to linear, high molecular weight D2‐meta‐decacarborane‐siloxanes was developed based on the condensation reaction between bisureidosilanes and carborane disilanol. By using NMR to monitor the reaction stoichiometry, polymers with molecular weight ≥250,000 have been prepared. Moreover, because of the mild reaction conditions, structural modifications of the polymer backbone have been readily achieved. These linear, high molecular weight polymers overcome the fabrication difficulties encountered in previously prepared D2‐polymers.
Polymerization of vinyl chloride with organolithium compounds. V. Flow behavior of concentrated solutions of high molecular weight poly(vinyl chloride) in cyclohexanone
Authors: Kudrna M. , Jíšová V. , Kolínský M. 
Published: April 2003

AbstractThe flow behavior of 10, 15, and 25% solutions of high molecular weight, thermally stable poly(vinyl chloride) in cyclohexanone was studied in the temperature range 50–140°C with respect to fiber‐forming properties. The flow behavior of such solutions at shear rates ranging from 1–103 sec−1 is pronouncedly non‐Newtonian with the exception of the 10% solution at 70°C. It can be adequately described by known empirical linear relationships. The apparent viscosities and activation energies are considerably higher than those for the usual types of poly(vinyl chloride), but vary within limits acceptable for the preparation and spinning of solutions.
Curing of epoxide resins: Model reactions of curing with amines
Authors: Dušek K. , Bleha M. , Luňák S. 
Published: April 2003

AbstractThe reaction of tetrafunctional diamines and bifunctional amines with monoepoxy compounds was investigated by gel‐permeation chromatography. At a stoichiometrically equivalent ratio of the functional groups or excess of amine, the consecutive reaction of the epoxide groups with the hydrogen atoms of the amino groups is the only reaction that is taking place; if epoxide is present in excess, the OH groups formed in the reaction are gradually added to the epoxide groups. The ratio of the rate constants of the reaction of the epoxy group with the hydrogen atoms of the primary and secondary amino group was calculated from the concentrations of the reaction products at various excess amounts of amines. The ratio is in good accord with the value calculated from the gel points and limiting stoichiometric ratios in the curing of diepoxides with diamines.
Investigations on poly(vinyl chloride). III. Effects of metal oxides upon thermal decomposition of poly(vinyl chloride)
Authors: Iida Takeo , Gotō Kunio 
Published: April 2003

AbstractThermal decomposition mechanisms of poly(vinyl chloride) (PVC) and the effects of a few metal oxides on the pyrolysis of PVC were previously reported. In the present work, 33 metal oxides were investigated to determine their effects on the thermal decomposition of PVC, by using a pyrolysis gas chromatograph. Most acidic oxides accelerate the recombination of chlorine atoms with double bonds, since PVC containing these metal oxides easily release lower aliphatics, toluene, ethylbenzene, o‐xylene, and chlorobenzenes. On the other hand, most basic metal oxides, such as oxides of alkaline earths or silver, inhibit the recombination. These tendencies observed in the thermal decomposition of PVC agree with the contributions of corresponding metal salts to the dehydrochlorination of PVC proposed by other workers. This means that thermal decomposition or dehydrochlorination of PVC is affected by irregularities in head‐to‐tail linkages formed by the recombination of chlorine atoms during heat treatment of PVC.
Polymerization of aromatic nuclei. XVI. Mechanism of chain propagation in the polymerization of benzene by aluminum chloride–cupric chloride
Authors: Engstrom Gary G. , Kovacic Peter 
Published: April 2003

AbstractA study was made of the mechanism of benzene polymerization by aluminum chloride‐cupric chloride. Our main effort was devoted to propagation with the aim of resolving a literature conflict as to whether a cationic or radical pathway is involved. When equimolar mixtures of benzene and haloarene are polymerized, the resulting copolymers are composed almost exclusively of benzene monomer. This approach is based on the known relative reactivities of the monomers toward electrophilic and radical species. The amount of haloaromatic present in the copolymer was determined by elemental analyses and confirmed by infrared spectroscopy. These results are strongly indicative of propagation by an electrophilic moiety. The presence of oxygen in the reaction mixture was found to have no significant effect on the rate or yield of the polymerization, in contrast to a previous published report. The progress of the reaction was followed by titration of the evolved hydrogen chloride. Phenyl radicals, obtained by the thermal decomposition of benzoyl peroxide in benzene, were found to be incapable of initiating the polymerization in the presence of cupric chloride. Increased yields of biphenyl and the presence of chlorobenzene point to oxidation of intermediate radicals by cupric chloride. None of the experimental evidence is satisfactorily interpreted by radical propagation. The data are nicely rationalized on the basis of cationic chain extension, apparently via a radical cation initiator.
Hydrophobicities in the domains of polyelectrolytes
Authors: Abe Koji , Koide Mikio , Tsuchida Eishun 
Published: April 2003

AbstractThe interactions of integral‐or pendant‐type polycations with sodium‐1‐anilino‐8‐naphthalene sulfonate (ANS) were studied by means of their fluorescent spectra. The emission maxima shift to the lower wavelength and fluorescent intensities increase greatly as a result of such complexations. This result may be attributed to the electrostatic interaction and the specific nonpolar environment around the bound ANS. The hydrophobic property in the domain formed by a polycation chain depends on the increase of methylene groups or the existence of a xylylene group between two adjacent cationic sites on the main chain, the existence of benzyl groups on the side chains, and the increase of their molecular weights. It is shown that the hydrophobicities in the domains of polyelectrolytes also change with their conformational changes, i.e., the more contracted their conformations are, the stronger their hydrophobicities are.