bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of polybenzamide–ureas from N‐mesyloxyphthalimide and diamines
Authors: Imai Yoshio , Ueda Mitsuru , Ishimori Motokazu 
Published: April 2003

AbstractNovel polybenzamide‐ureas have been synthesized by the polymerization of N‐mesyloxyphthalimide with diamines in N‐methyl‐2‐pyrrolidone in the presence of acid acceptors. The polymerization probably proceeds through the formation of ring‐opened adducts, followed by elimination and rearrangement yielding 2‐isocyanatobenzamide derivatives, which were subsequently reacted to give polybenzamide‐ureas. These polymers had inherent viscosities of 0.12–0.34 and were soluble in a wide range of solvents, including pyridine and m‐cresol, as well as polar aprotic solvents. All of the polymers had low softing temperatures in the range of 140–260°C, and thermal analyses showed that marked decomposition of the polymers occurred at around 200–300°C, presumably forming quinazolinedione rings by intramolecular deamination.
Reactions catalyzed by soda lime glass. III. Molecular weights of poly(methyl methacrylate) prepared in aqueous media with NaHSO3 as initiator
Authors: Moustafa A. B. , Ghanem N. A. , Diab M. A. 
Published: April 2003

AbstractThe polymerization of methyl methacrylate (MMA) was carried out in water by use of various concentrations of sodium bisulfite as initiator in the presence and absence of colorless and colored soda lime glass at 40°C. The reaction products were filtered, washed with water, methanol and finally dried at 50°C. The glass–polymer combination was subjected to Soxhlet extraction with benzene. The molecular weights of the soluble polymers were determined viscometrically. In the absence of glass, the conversion was lower but the average molecular weights were higher than in presence of soda lime glass. The effect of grain size of the glass on conversion and molecular weights was such that larger grain size of glass resulted in lower conversion and higher average molecular weights.
The conversion of halogen‐containing polymers to the corresponding hydroxyl derivatives
Authors: Cohen H. L. 
Published: April 2003

AbstractThe direct conversion of poly(epichlorohydrin), poly[3,3‐bis(chloromethyl)oxetane], and poly‐(vinyl chloroethyl ether) to the corresponding hydroxyl‐containing polymers is described. The replacement of the halogen atom in several chlorine‐containing polymeric esters by an acetyl group and the subsequent conversion of the latter derivatives to hydroxyl‐containing polymers is also described.
Thermal polymerization of styrene in the presence of some ferrocene derivatives. I. Evidence of ferrocene–styrene interaction
Authors: Tinker A. J. , George M. H. , Barrie J. A. 
Published: April 2003

AbstractStyrene has been polymerized thermally at 60.5°C, without added initiator, in the presence of ferrocene. An increase in the rate of polymerization was observed, but the degree of polymerization remained constant. Evidence of ferrocene–styrene interaction is presented, and a kinetic scheme involving propagation with styrene in such an interaction state is proposed to account for these findings. Various kinetic parameters defined by this scheme have been evaluated.
Photosensitized polymerization of methyl methacrylate with acriflavine dye
Authors: Chakrabarti Krishna Pada 
Published: April 2003

AbstractThe kinetics of photopolymerization by ultraviolet‐light with acriflavine as the sensitizer was studied in nonaqueous medium. The reducing agent used was alcohol. The rates of the photopolymerization were determined dilatometrically. The order of the reaction with respect to the sensitizer concentration was 0.14 while that with respect to the reducing agent concentration was 0.8 × 10−1. These results are interpreted in terms of a kinetic scheme which involves a competitive ground‐state deactivation of the dye triplet and photoreduction. A low initiator efficiency of the primary radicals (cage recombination) and bimolecular termination processes are assumed.
Kinetics of the homopolymerization of vinylferrocene in dioxane in the presence of 2,2′‐azobisisobutyronitrile
Authors: Tinker A. J. , George M. H. , Barrie J. A. 
Published: April 2003

AbstractThe kinetics of the AIBN‐initiated homopolymerization of vinylferrocene in dioxane has been investigated at 60°C. The rate of polymerization was found to be dependent on the monomer concentration to a power 0.97 and on the initiator concentration to a power 0.42. The overall activation energy for polymerization over the range 50–80°C was 84 kJ/mole. Analysis of polymer molecular weight data gave the chain transfer constant to monomer Cm as 1.2 × 10−2 and analysis of both rate and molecular weight data gave kp/(kt)0.5 as 2.36 × 10−2 dm1.5/mole0.5‐sec0.5. Mössbauer and ESR spectra indicated the absence of Fe(III)‐containing paramagnetic species in the polyvinylferrocene formed under these conditions.
Poly(alkyl α‐chloroacrylates). V. Preparation and properties of methyl, ethyl, and isopropyl polymers of varied tacticity
Authors: Dever G. R. , Karasz F. E. , MacKnight W. J. , Lenz R. W. 
Published: April 2003

AbstractPolymers of different tacticities, from highly isotactic to highly syndiotactic, were prepared from methyl, ethyl, and isopropyl α‐chloroacrylates. These polymers were characterized for tacticity by infrared spectroscopy and 100 and 300 MHz nuclear magnetic resonance (NMR) and for thermal properties by differential scanning calorimetry (DSC). After corrections were made for molecular weight effects, the observed glass temperature‐tacticity results were analyzed, and it was determined that the maximum differences in glass temperatures of the purely isotactic compared to the purely syndiotactic polymers should be 92°C for the methyl ester, 86°C for the ethyl ester, and 68°C for the isopropyl ester polymers. The highly isotactic polymers of all three esters were crystalline. Possible polymerization reaction mechanisms are discussed on the basis of the triad and tetrad tacticity values observed and the calculated propagation statistics.
Synthesis of aromatic polymers containing anthrazoline and isoanthrazoline units
Authors: Imai Y. , Johnson E. F. , Katto T. , Kurihara M. , Stille J. K. 
Published: April 2003

AbstractThe condensation of bisketomethylene monomers with either 4,6‐dibenzoyl‐1,3‐phenylenediamine or 2,5‐dibenzoyl‐1,4‐phenylenediamine catalyzed by acid affords high molecular weight polymers containing the anthrazoline and isoanthrazoline units in the polymer main chain. Base is not an effective catalyst for the production of high molecular weight polymer. The phenyl substitution on the anthrazoline and isoanthrazoline units increases the solubility of these polymers over those in which phenyl substitution is absent. The rodlike character of these polymers, which can be altered by positional isomerism in the chain, has an effect on the solution properties.
Photochemical processes involving TiO2 pigments and TiO2–light stabilizer combinations in commercial polyolefins
Authors: Allen N. S. , McKellard J. F. , Wood D. G. M. 
Published: April 2003

AbstractThe photoactivity of titania pigments at different loadings in both polyethylene and polypropylene is examined by phosphorescence and carbonyl formation and a correlation between the two observed. A nickel (II) chelate stabilizer proved more effective than a hydroxybenzophenone stabilizer in the presence of anatase. This difference in stabilizing efficiency appears to be due to more efficient quenching of the excited state of the anatase by the nickel chelate than by the hydroxybenzophenone.
Radiation‐induced heterogeneous polymerization of acrylamide in acetone and acetone–water mixtures
Authors: Wada Takeshi , Sekiya Hiroshi , Machi Sueo 
Published: April 2003

AbstractThe effects of temperature, dose rate, and monomer concentration on the heterogeneous polymerization of acrylamide in acetone–water mixtures have been studied. Heterogeneous polymerization takes place in mixtures containing less than 60 vol‐% water. The polymerization is steady in acetone and nonsteady in acetone an nonsteady in mixtures containing 10–50 vol‐% water. The average rate of polymerization is highest in mixtures with about 20 vol‐% water. Polymer molecular weight increases with the increasing water content in range 0–10 vol‐% and does not change in the range of 30–70 vol‐% water. For the polymerization in acetone and an acetone–water 60/40 mixture the activation energies are 2.3 and −1.8 kcal/mole, the dose rate exponents of rate are 0.78 and 0.52, and the monomer concentration exponents of rate are 0.5 and 1.6, respectively. The polymer molecular weight increases with decreasing dose rate, decreasing temperature, and increasing monomer concentration. These results are discussed in connection with the mechanism of heterogeneous polymerization and the solvent effect.
Four‐center type photopolymerization in the solid state. VII. Photochemical reaction of m‐phenylene diacrylic acid dimethyl ester
Authors: Nakanishi Fusae , Nakanishi Hachiro , Hasegawa Masaki , Yamada Yoshiji 
Published: April 2003

AbstractThe photochemical reaction of m‐phenylene diacrylic acid dimethyl ester (m‐PDA Me) crystals and solutions has been studied to clarify the effects of the molecular shape on four‐center type photopolymerization of diolefins. On irradiation, m‐PDA Me crystals were converted into amorphous oligomers having more than two kinds of cyclobutane rings with respect to steric configuration. The characteristic oligomer formation is explained by considering a two‐step mechanism: topochemical dimer formation in an ordered crystal lattice and subsequent random cycloaddition in a disordered crystal lattice. In m‐PDA Me solution, reversible cyclobutane ring formation and cis–trans isomerization take place, depending on the concentration of m‐PDA Me in solution and the wavelength of the irradiating light. The multiplicity of reactivity in various states has been established.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. VII. Polymers with [2.2]‐p‐cyclophane units
Authors: Chang Daniel M. , Marvel C. S. 
Published: April 2003

Abstract1,3‐Bis(p‐phenoxybenzenesulfonyl)benzene (I), 4,4′‐diphenoxy‐diphenyl sulfone (II), diphenyl ether, and 3,9‐bis(p‐phenoxybenzoyl) [2.2]‐p‐cyclophane were polymerized with isophthaloyl chloride in Friedel‐Crafts type polymerization. The polymers obtained, containing 6–8 wt.‐% of p‐cyclophane units were moderately soluble in HMPA and sulfuric acid with inherent viscosities, between 0.5 and 1.0. The polymers cured at 375°C for 3 days showed little penetration up to 400°C in the Vicat softening curves. Strong molding disks and laminates on glass fiber can be made with excellent thermal stability.
Effects of trivalent phosphorus compounds on vinyl polymerization. III. Anionic polymerization of acrylonitrile with triethyl phosphite
Authors: Ogawa Takeshi , Quintana Patricia 
Published: April 2003

AbstractThe polymerization of acrylonitrile catalyzed by triethyl phosphite was studied. It was found that the order with respect to the monomer concentration varies from two to three, depending on the polymerization temperature. From the results obtained for the molecular weight of the polymer and the phosphorus content in the polymer, it was thought that the zwitterion formed by the addition of triethyl phosphite to acrylonitrile is responsible for the initiation of polymerization. The following equation was suggested for the rate of the polymerization:
Synthesis of polyarylaminophosphazenes
Authors: White J. E. , Singler R. E. , Leone S. A. 
Published: April 2003

AbstractThe synthesis of a series of Polybis(arylamino)phosphazenes is described. The polymers usually were prepared by treatment of polydichlorophosphazene in benzene–tetrahydrofuran with arylamines/triethylamine at reflux for 48–144 hr. The polymers, having viscosities of 0.3–1.4dl/g, are essentially free of active chlorine sites, as shown by elemental analysis and their longterm hydrolytic stability. Thermal analysis revealed glass transition temperatures between 53 and 105°C and decomposition temperatures between 243 and 266°C. Analysis by differential scanning calorimetry revealed no first‐order endothermic transitions. For comparison with the arylamino polymers, polydiethylaminophenylaminophosphazene, polybis(benzylamino)phosphazene, and polybis(β‐phenethylamino)phosphazene were prepared and are described.
Preparation of films exhibiting a balanced temperature dependence to permeation by aqueous solutions—a study of lower consolute behavior
Authors: Taylor Lloyd D. , Cerankowski Leon D. 
Published: April 2003

AbstractTemperature dependence of solute transport through aqueously swollen polymeric films and membranes can be altered to show even apparent negative activation energies by the use of polymers exhibiting a lower consolute behavior in solution. The principles by which we constructed a host of such polymers are discussed. A solubility rule is presented which predicts that solutes in water will show a lower critical solution temperature if the proper hydrophilic–hydrophobic balance is achieved.
Anionic polymerization of vinyl chloride
Authors: Wesslén Bengt , Wirsén Anders 
Published: April 2003

AbstractAnionic polymerization of vinyl chloride has been studied. Of the organometallic compounds tested as initiators, only butyllithium was found to initiate polymerization. Polymerization in bulk at 0°C and with tert‐butyllithium as initiator gave poly(vinyl chloride) in a yield of 38% with Mn = 55,000. Tacticity of the anionic PVC was similar to that of conventional PVC prepared at similar temperatures. Anionic PVC was found to be less branched and more heat‐stable than the conventional polymer.
Studies on polymers from cyclic dienes. XIV. Cationic polymerization of spiro[2,4]hepta‐4,6‐diene with triphenylmethyl initiators
Authors: Kunitake Toyoki , Ochiai Takeharu , Ohara Osamu 
Published: April 2003

AbstractSpiro[2,4]hepta‐4,6‐diene, a derivative of cyclopentadiene, was polymerized at −76°C with various triphenylmethyl salts as initiator. The polymer consists only of the 1,2‐ and 1,4‐addition structures, and their contents can be determined by the relative area of the olefin proton peaks. The polymer structure changed characteristically with the polymerization conditions. The content of 1,4‐structure decreased with increasing polarity of the medium from 45–70 in toluene to 25–30% in 7:3 CH2Cl2–CH3CN. In 1:1 CH2Cl2–toluene, the 1,4‐structure content decreased from 70% to 40% with increasing radii of counteranions. These results were interpreted according to the model of the cationic propagation proposed earlier, as arising from the different tightness of the propagating ion pair. In the case of pentacoordinate counteranions, in particular SnCl5−, the 1,4‐structure content was greater than expected from the anion size alone and decreased with increasing initiator concentrations, in contrast with the behavior of the other tetra‐ and hexacoordinate anions. This was attributed to the possibly facile aggregation of the pentacoordinate anion. However, the common ion effect was not observed.
Effects of diffusion in the oxidative degradation of vulcanized rubbers. I. Rate of chain scission in the steady state
Authors: Ono Katsumichi , Kaeriyama Akitoshi , Murakami Kenkichi 
Published: April 2003

AbstractThe effects of diffusion in the oxidation of cis‐1,4‐polyisoprene vulcanizates were investigated by means of the stress relaxation method. It was assumed that the diffusion of oxygen is coupled with first‐order oxygen consumption and that the rate of chain scission is proportional to the rate of oxygen consumption. The diffusion equation of this process was solved under the steady‐state condition to give a simple relation between the rate of chain scission and the film thickness. The experimental results were in good agreement with the theoretical treatment. The true activation energy as well as the ratio of the rate of oxidation k to the diffusion constant D could be estimated.
Formation of free radicals in photoirradiated cellulose. VII. Radical decay
Authors: Hon Nyok‐Sai 
Published: April 2003

AbstractThe ESR spectra of untreated and photosensitized celluloses irradiated with three different ultraviolet light sources, i.e., λ > 2537 Å, λ > 2800 Å, λ > 3400 Å, at 77°K under vacuum were studied. Based on the warm‐up process, that is, warming the sample from 77°K to 273°K for a certain time and recorded at 77°K, the decay behavior of free radicals of celluloses was examined for changes of the pattern and the intensities of ESR spectra. For the untreated samples irradiated with light of λ > 2537 Å and λ > 2800 Å, beside the two doublet spectra originating from hydrogen atoms (508 gauss splitting) and formyl radicals (129 gauss splitting), the observed sevenline spectrum was resolved to be a superposition of a singlet (ΔHmsl = 16 gauss), a doublet (24 gauss splitting), a triplet (34 gauss splitting), and a quartet (overall width, 88 gauss) spectrum. For the photosensitized samples irradiated with light of λ > 3400 Å, the 1:1:1 three‐line spectrum was resolved to be a superposition of a singlet (ΔHmsl = 27 gauss), a doublet (43 gauss splitting), and a triplet (34 gauss splitting) spectrum. The five‐line spectra of the photosensitized samples irradiated with light of λ > 2537 Å and λ > 2800 Å were resolved to be a superposition of a singlet (ΔHmsl = 27 gauss), a doublet (43 gauss splitting), and a triplet (34 gauss splitting) spectrum. Based on these findings, the conclusion was drawn that at least six kinds of spectra, generated from six kinds of radical species, were formed in cellulose irradiated with ultraviolet light under appropriate experimental conditions.
Photoinitiation. II. Kinetics of the acrylonitrile polymerization photoinitiated by aromatic hydrocarbons
Authors: Bartoň Jaroslav , Capek Ignác , Hrdlovič Pavol 
Published: April 2003

AbstractThe kinetics of acrylonitrile polymerization photoinitiated by aromatic hydrocarbons have been studied. For the acrylonitrile polymerization photoinitiated by naphthalene the rate of polymerization depends on the square root of incident light intensity, on the square root of naphthalene concentration, and on the 1.5 power of acrylonitrile concentration. In the system acrylonitrile‐1‐methoxynaphthalene the rate of acrylonitrile polymerization depends on the first power of acrylonitrile concentration. The monoradical character of this polymerization process has been established. For the interpretation of experimental results a reaction mechanism involving the formation of the exciplex between the first singlet or triplet of aromatic hydrocarbon and acrylonitrile in the ground state as a precursor of polymerization reactions is suggested. The photoinitiating efficiency of various aromatic hydrocarbons in acrylonitrile polymerization increases in the order: fluoranthene (zero efficiency) ≪ pyrene < phenanthrene, fluorene ≈ 2‐methoxynaphthalene ≈ biphenyl < anthracene < 2‐methylnaphthalene < 1‐methoxynaphthalene < 2,3,6‐trimethylnaphthalene < 2,3‐dimethylnaphthalene ≈ naphthalene < 1‐methylnaphthalene < 2,6‐dimethylnaphthalene < p‐terphenyl < acenaphthene, provided that the systems absorb the same amount of the incident light. The explanation of this result ensues from the study of the effect of concentration on the rate of polymerization and from the quenching of hydrocarbon fluorescence by acrylonitrile. The photoinitiating efficiency of a given aromatic hydrocarbon is mainly determined by the value of the rate constant kq for the formation of exciplex as well as the self‐quenching efficiency of aromatic hydrocarbon. By using the literature data for the lifetime of fluorescence τ the values of kq were calculated from the Stern‐Volmer equation expressing the quenching of hydrocarbon fluorescence by acrylonitrile. The order of aromatic hydrocarbons according to increasing values of kq is as follows: pyrene < phenanthrene < anthracene ≈ naphthalene < 2‐methylnaphthalene ≈ 1‐methylnaphthalene ≈ 2,3‐dimethylnaphthalene < 2,6‐dimethylnaphthalene < acenaphthene < p‐terphenyl < 1‐methoxynaphthalene. The study of the concentration effect reflecting the self‐quenching of aromatic hydrocarbons during polymerization has given the following sequence for decreasing self‐quenching efficiency of aromatic hydrocarbons: 2‐methoxynaphthalene ≈ pyrene > anthracene > 1‐methoxynaphthalene > fluorene > 2,6‐dimethylnaphthalene, phenanthrene, acenaphthene > 2,3,6‐trimethylnaphthalene > 2,3‐dimethylnaphthalene > 1‐methylnaphthalene > naphthalene. It has been shown that the photoinitiating efficiency of a given aromatic hydrocarbon in the polymerization of acrylonitrile can be roughly predicted from the position of that aromatic hydrocarbon in the above‐mentioned sequences.
Photoinitiation. III. Polymerization of acrylonitrile photoinitiated by benzophenone in the presence of naphthalene
Authors: Capek J. , Bartoň J. 
Published: April 2003

AbstractThe polymerization of acrylonitrile photoinitiated by radiation of wavelengths 313 and 365 nm in the presence of benzophenone and naphthalene was studied. If radiation of wavelength λ = 313 nm which is absorbed by naphthalene as well as by benzophenone is used, a decrease of the acrylonitrile polymerization rate and of the molecular weight of the polymer is observed in comparison with the polymerization taking place in the absence of benzophenone. If a radiation of wavelength (λ = 365 nm) at which only benzophenone is excited is used, addition of naphthalene to the system acrylonitrile–benzophenone enhances the polymerization rate. The reaction mechanism which accounts for the observed behavior of the acrylonitrile polymerization is discussed.
Electroinitiated oligomerization of methyl acrylate in methanol solution
Authors: Albeck Michael , Karoly Aharon 
Published: April 2003

AbstractThe electroinitiated oligomerization of methyl acrylate in methanol solution in the presence of lithium acetate was studied. It was found that in this system the initiator is the methyl radical (obtained from anodic oxidation of acetate ion), and the major termination step is the abstraction of hydrogen radical from methanol by the growing oligomer chain. Eleven compounds were found to be formed in the reaction. A reaction sequence for their formation together with an electric balance for the reactions is given.
Toxic gas evolution from polymers: Evolution of hydrogen cyanide from linear polyurethane
Authors: Jellinek H. H. G. , Takada K. 
Published: April 2003

AbstractHCN evolution from linear polyurethane has been studied over a range of temperatures from 261 to 480°C as function of exposure time, oxygen pressure, film thickness, and chain length. Infrared spectra have also been measured as function of exposure time. In addition, gas evolution during thermal degradation in vacuo has been investigated in a quartz spoon reaction vessel. Rate constants and energies of activation have been evaluated for all reactions. Gas evolution and adsorption are diffusion‐controlled during thermal and thermal‐oxidative degradation up to at least 330°C. Thermal degradation consists essentially of a reversal of the polycondensation process. The thermal‐oxidative degradation is a complicated reaction involving chain scission, crosslinking, carbonization, and gas evolution. HCN evolution, although appreciable, is only a minor side reaction of the total oxidation process. A tentative mechanism for HCN evolution has been proposed.