bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge‐transfer polycondensation of diethyl chelidonate with hexamethylenediamine
Authors: Ogata N. , Shimamura K.
Published: April 2003

Polycondensation of diethyl chelidonate (DEC) with hexamethylenediamine (HMD) took place very rapidly under mild conditions to form a corresponding polyamide. The polycondensation reaction proceeded through the formation of a charge‐transfer complex between DEC and HMD, which transformed rapidly into polyamide. Various reaction conditions to form polyamide from DEC and HMD were investigated in terms of solvents, concentration, and temperature. Model reaction of DEC with primary or tertiary amines confirmed the formation of a charge‐transfer complex which transformed into chelidonamide except tertiary amine. The polycondensation of DEC with HMD was accelerated by irradiation with light.
Polymerization of α‐amino acid N‐carboxy anhydrides initiated by histamine in N,N‐dimethylformamide
Authors: Tsuchida Eishun , Hasegawa Etsuo , Honda Kenji
Published: April 2003

The polymerization of α‐amino acid N‐carboxy anhydrides (NCAs) initiated by 4‐aminoethylimidazole (histamine) was studied in order to synthesize poly(amino acids) containing an imidazole nucleus at the end of polymer chain. On the basis of the kinetical measurements, it was found that the rate of polymerization is proportional to the first order in both NCA and initiator concentrations and that the initiation reaction is predominantly caused by the primary amine with the highest basicity in a histamine molecule. Binding of the histamine fragment to the end of polymer chain was confirmed by elementary analysis, nuclear magnetic resonance spectroscopy, and measuring the number‐average molecular weight of the resulting polymers. It was thus possible to prepare poly(amino acids) with a pendant histamine. In addition, the lowering of the number‐average degree of polymerization of the polymers prepared was observed under the condition that the initial molar ratio of NCA to histamine was larger. It was caused by the reinitiation of polymerization by the imidazole nucleus at the chain end.
Photocrosslinkable resins with benzylideneacetophenone (chalcone) structure in the repeat units
Authors: Panda S. P.
Published: April 2003

Syntheses, characterization and photoreactions of six diglycidyl ethers obtained by condensing 2,2′, 2′,4, and 4,4′‐dihydroxychalcones with epichlorohydrin in two different molar proportions have been reported. It has been observed that the well known cyclodimerization and trans‐cis isomerization of the chalcone moiety under photoirradiation could be significantly affected to the extent of completely supressing the isomerization in 2,2′, and 2′,4‐chalconic resins by steric factors. Increase in molecular weight made the photodimerization difficult in the 2,2′, and 2′,4‐chalocnic resins whereas the 4,4′‐chalconic resin remained unaffected. It has been suggested that the chalconic resin could be used in photomechanical processes mixed with aryldiazonium fluoroborates. These additives are known to decompose under photoirradiation yielding BF3 which is a crosslinking agent for the epoxide group.
Polymérisation anionique des diènes. IV. Contribution aux etudes des mécanismes de propagation stéréospécifique des isoprène et butadiène par les organo‐alcalins
Authors: Essel Alain , Salle Robert , Pham Quang‐Tho
Published: April 2003

By taking into account different possible interactions between the living end, the counterion and the nature of the solvent used on the one hand, and the influence of the temperature on the kinetics and the microstructures of polydienes on the other hand, it has been possible to suggest some new explanations concerning the mechanisms of the anionic propagation of butadiene and isoprene. In hydrocarbon media, the stereospecificity of the 1,4 propagation initiated by lithium should be considered as the consequence of the coordination of the counterion by both of the two bonds of the diene molécule. The stereospecificity of the vinyl propagation by the same counterion in dioxane solvent should be the consequence of the competition between the (Li+, dioxane) and (Li+, diene) coordination complexations. In this case, the Li+ counterion should only be coordinated by only one of the two double bonds of the diene molecule. With isoprene, the π‐electron donation should originate mainly from the C3C4 double bond. The decrease of the stereospecificity is due to the increasing size of the alkali counterion and the separation or the dissociation of the growing ion‐pairs.
Influence of the reaction medium on the composition and the microstructure of styrene–acrylic acid copolymers
Authors: Toppet S. , Slinckx M. , Smets G.
Published: April 2003

Two series of acrylic acid‐styrene copolymers of various composition have been prepared in benzene and dimethylformamide in order to study their sequence distribution by using 13C NMR spectroscopy. The reactivity ratios in benzene were rA = 0.13, rA = 0.30 and in dimethylformamide rA = 0.05, rS = 1.60. Copolymers with the same overall composition but prepared in different media display marked differences in sequence distribution, the copolymers obtained in dimethylformamide always having longer sequences. For the series of copolymers prepared in dimethylformamide, the experimental percentages of acrylic acid‐centered triads (SAS, SAA, AAA) disagree with the values calculated from the monomer reactivity ratios.
Polyene sequence distribution in thermally degraded poly(vinyl chloride)
Authors: Abbås K. B. , Laurence R. L.
Published: April 2003

A kinetic model for the formation of polyene sequences during the thermal degradation of poly(vinyl chloride) in nitrogen is proposed. The model includes a propagation step of the “zipper” type and termination by crosslinking. The initiation can occur randomly or at weak links in the polymer chain. The rate of polyene growth increased with increasing polyene sequence length and passed through a flat maximum at n = 7. The average polyene sequence length was almost constant up to about 0.5% conversion, but then slowly decreased with increasing conversion. This was the result of a larger extent of termination reactions (crosslinking) at higher conversions. At 0.2–0.5% conversion an average polyene sequence length of about 6 was observed. The degradation was carried out in nitrogen at 190°C. The experimental results were obtained from ultraviolet‐visible spectrophotometric measurements.
Crosslinking and pyrolytic behavior of natural and man‐made cellulosic fibers
Authors: Rodrig H. , Basch A. , Lewin M.
Published: April 2003

Pyrolysis rates, energies of activation, and DSC data were obtained for cellulosic fibers crosslinked with increasing amounts of formaldehyde. Pyrolysis rates are affected by the reduction in degree of polymerization, the breaking of intermolecular hydrogen bonds, and the introduction of covalent linkages that accompany the crosslinking process. Thermal stabilization of cellulose is related mainly to the formation of interchain crosslinks. The influences of the crystallinity and orientations of the polymers upon changes in thermal stability and pyrolytic behavior due to crosslinking are demonstrated.
Synthesis of polybenzamide–ureas from N‐mesyloxyphthalimide and diamines
Authors: Imai Yoshio , Ueda Mitsuru , Ishimori Motokazu
Published: April 2003

Novel 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

The 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

The 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

Styrene 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

The 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

The 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

Polymers 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

The 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

The 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

The 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

The 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

1,3‐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

The 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

The 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

Temperature 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

Anionic 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

Spiro[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

The 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

The 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

The 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

The 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

The 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

HCN 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.
Synthesis of functional polyamides by the ritter reaction
Authors: Ogata Naoya , Saito Kenshi
Published: April 2003

Polyamides having pendant functional groups such as hydroxyl, mercapto, or imine groups were synthesized by the Ritter reaction of dinitriles and trioxane in concentrated sulfuric acid. The polymerization of β‐hydroxyl glutaronitrile yielded a water‐soluble polyamide having a low molecular weight which might be ascribed to the participation of the hydroxyl group with the polymerization, while the polymerization of β‐mercaptoglutaronitrile resulted in the formation of a crosslinked polyamide which was insoluble in common solvents. Polymerization of dinitriles having imine groups yielded water‐soluble polyamides which were effective as a coagulation agent for colloidal solutions.
Graft polymerization of vinyl monomers onto cellulose in presence of soda lime glass. II
Authors: Mansour Olfat Y. , Moustafa Abd‐Allah B.
Published: April 2003

In the sodium bisulfite–soda lime glass initiating system, crude and true grafting yields increased with increasing ratio of methyl methacrylate to cellulose up to a limit; beyond this limiting value, grafting yields decreased due to the increase of the rate of sodium bisulfite‐monomer addition over that of polymerization. Limitation was also achieved on increasing the glass to cellulose ratio through increased termination rates by coupling and disproportionation reactions, as the free radicals are increased. In addition, a limiting value was reached with increasing sodium bisulfite concentration; this may be related to the formation of a nonfunctioning disulfite ion at the expense of bisulfite radicals at high concentrations of sodium bisulfite. The temperature plays a role in this initiating system. Maximum rates of conversion and grafting were achieved at the ceiling temperature. Dissociation of the sodium bisulfite, which decreases with temperature, also has an effect.
Aromatic polyethers, polysulfones, and polyketones as laminating resins. VI. Polymers from 2,5‐dicyanoterephthalic acid
Authors: Bruma Maria , Marvel C. S.
Published: April 2003

Aromatic poly(keto ether sulfones) containing various amounts of pendant cyano groups were synthesized from 1,4‐bis(p‐phenoxybenzoyl)‐2,5‐dicyanobenzene, 1,3‐bis(p‐phenoxybenzenesulfonyl)benzene, and isophthaloyl chloride by a Friedel‐Crafts type polymerization. These polymers softened at 160–190°C and had inherent viscosities of 0.44–0.61 in hexamethylphosphoric triamide. Crosslinkings were made by heating the polymers alone or in the presence of zinc chloride at 360–370°C to give black resinous materials that were insoluble in hexamethylphosphoric triamide in which the original polymers dissolved quite readily.
Determination of coisotacticities of some alternating styrene–acrylic copolymers by NMR spectra
Authors: Yokota Kenji , Hirabayashi Tadamichi
Published: April 2003

Coisotacticities σ for some alternating copolymers were determined through the analyses of their CH3O, CH3 and CH2 proton NMR spectra; styrene–methyl methacrylate (σ = 0.56), styrene‐methyl acrylate (σ = 0.53), styrene–methyl α‐chloroacrylate (σ = 0.69), styrene–methacrylonitrile (σ = 0.19), styrene–methacrylamide (σ = 0.16), α‐methylstyrene–methyl methacrylate (σ = 0.21), and α‐methylstyrene–methyl acrylate (σ = 0.53) were studied. It was found that a terminal model or Bernoullian trial prevails in these complexed copolymerizations with diethylaluminum chloride. The influence of monomer structure on σ values is discussed.
Copolymerization of trioxane with cyclic acetals. Effect of catalyst on polymerization and monomer reactivity
Authors: Chen Catherine S. Hsia
Published: April 2003

The copolymerization of trioxane with cyclic acetals, viz., 1,3‐dioxolane, m‐dioxane, and 4‐methyl‐m‐dioxane, have been investigated. Three types of catalyst have been employed: a metal chelate, MoO2(AcAc)2; a Lewis acid, BF3·Bu2O; and an ion‐pair,
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It has been ascertained that, in agreement with the previous results on copolymerization of trioxane and ethylene oxide,1 both the polymerization kinetics and the monomer reactivity have been found to be influenced by the catalyst employed. In copolymerization with 1,3‐dioxolane, both BF3·Bu2O and
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have been found to give high molecular weight copolymers with high incorporation of 1,3‐dioxolane. However, contrary to the results obtained in copolymerization with ethylene oxide, higher rate and yield have been obtained with BF3·Bu2O, making it a superior catalyst. In copolymerization with m‐dioxane,
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has been found to be a superior catalyst to the others yielding high molecular weight copolymers with high incorporation of m‐dioxane. In copolymerization with 4‐methyl‐m‐dioxane, MoO2(AcAc)2 has been found to be an overall superior catalyst to the others. Higher rate, yield, and comonomer incorporation have been obtained using MoO2(AcAc)2 as catalyst, although somewhat higher molecular weight copolymers have been obtained with
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Poly(vinyl chloride‐g‐butyl rubber)
Authors: Kennedy J. P. , Davidson D. L.
Published: April 2003

The synthesis of poly(vinyl chloride‐g‐butyl rubber) and some of its physical properties are described. The key to the synthesis involves copolymerization initiation of an isobutylene–isoprene charge by a PVC/Et2AlCl initiator system with 1,2‐dichloroethane as solvent. The graft is a thermoplastic; cast films are flexible and optically clear. Proof of grafting is the crosslinking with S2Cl2 of the pentane‐extracted product in THF solution. Crosslinking the butyl rubber moiety in the graft reduces overall stress properties.
Polyimidothioethers
Authors: Crivello James V.
Published: April 2003

The condensation of maleimide compounds with hydrogen sulfide and bisthiols was studied in several model systems. Bismaleimide compounds undergo rapid, exothermic polymerization with thiol‐containing compounds in dipolar and basic solvents to give crosslinked polymidothioethers. Effective supression of the crosslinking reaction was achieved by carrying out the polymerization in the presence of a proton donor to inhibit anionic polymerization. A number of linear polyimidothioether homopolymers and copolymers were prepared and a study was made of their properties.
Polymerization of coordinated monomers. IX. Charge‐transfer spectrum of the system composed of metal halide, polar vinyl monomer, and electron‐donating monomer
Authors: Komiyama Makoto , Hirai Hidefumi
Published: April 2003

The 1:2 stannic chloride–methyl methacrylate complex, the 1:2 stannic chloride–acrylonitrile complex, the ethylaluminum dichloride–methyl methacrylate complex, and the ethylaluminum dichloride–acrylonitrile complex exhibit charge‐transfer absorption bands in the wavelength region longer than 300 nm with electron‐donating compounds such as mesitylene, styrene, toluene, and butadiene. The absorption spectrum of the mixture of either methyl methacrylate or acrylonitrile with the electron‐donating compound is, however, a superpostion of the spectra of the components without any additional absorption. Methyl isobutylate, 3‐butenyl methyl ketone, and propionitrile show no charge‐transfer absorption bands with the electron‐donating compound, even in the presence of a metal halide. Both the presence of the C‐C double bond conjugating with the polar group and the coordination of the polar group to a metal halide are essential for an electron‐accepting monomer to exhibit a charge‐transfer absorption with the electron‐donating compound. Continuous variation plots with the use of the charge‐transfer band definitely show a 1:1 interaction between the methyl methacrylate coordinated to stannic chloride and styrene, resulting in the determination of the equilibrium constants for the charge‐transfer complex formation in methylene chloride: 0.21 l./mole at 25°C and 0.67 l./mole at −50°C. The charge‐transfer absorption is attributed to a ternary molecular complex composed of a metal halide, a polar vinyl monomer, and an electron‐donating monomer.
Plasma polymerization of some organic compounds and properties of the polymers
Authors: Yasuda H. , Bumgarner M. O. , Marsh H. C. , Morosoff N.
Published: April 2003

Plasma polymerizations (under 13.5‐MHz radiofrequency inductively coupled glow discharge) of some organic compounds are investigated by their properties (elemental analysis, surface energy, and infrared spectra) and their relations to the concentrations of free radicals in the polymers as detected by electron spin resonance (ESR) spectroscopy. Monomers that have been investigated are hexamethyldisiloxane, tetrafluoroethylene, acetylene, acetylene/N2, acetylene/H2O, acetylene/N2/H2O, allene, allene/N2, allene/H2O, allene/N2/H2O, ethylene, ethylene/N2, ethylene oxide, propylamine, allylamine, propionitrile, and acrylonitrile. Plasma‐polymerized polymers generally contain oxygen, even if the starting monomers do not contain oxygen. This oxygen incorporation is related to the free‐radical concentration in the polymer. Molecular nitrogen copolymerizes with other organic monomers such as acetylene, allene, and ethylene, and their properties are very similar to those of plasma‐polymerized polymers from nitrogen‐containing compounds such as amines and nitriles. The addition of water to the monomer mixture reduces in a dramatic manner the concentration of free radicals in the polymer and consequently the oxygen‐incorporation after the polymer is exposed to air. The concentrations of free radicals (by ESR) are directly correlated to the change of the properties of plasma‐polymerized polymers with time of exposure to the atmosphere. These changes are primarily the introduction of carbonyl (and possibly hydroxyl) groups. The addition of water to the plasma introduces these groups during the polymerization.
Polyimide structure–property relationships. I. Polymers from fluorene‐derived diamines
Authors: Bell Vernon L.
Published: April 2003

A series of fluorene and fluorenone diamines were polymerized with two aromatic dianhydrides, and the resulting polyamic acids were cyclodehydrated to aromatic polyimides. A study of the mechanical properties of the polyimide films disclosed they are among the stiffest reported to date, with an excellent retention of rigidity at elevated temperatures. Comparisons of the tensile properties and glass transition temperatures of the fluorene‐derived polymer films with those from the corresponding open‐chain polyimide films established that the unusual rigidity, especially at elevated temperatures, was in large part due to the contribution of the bulky, tricyclic fluorene (one) moieties in the polymer structures.
1H‐NMR spectra of complexes between methacrylic monomer and ethylaluminium dichloride in toluene and methylene chloride
Authors: Furukawa Junji , Kobayashi Eiichi , Nagata Shiro
Published: April 2003

1H‐NMR spectra of mixtures of a methacrylic monomer such as methacrylonitrile or methyl methacrylate and ethylaluminium dichloride at various molar ratios were measured in toluene or methylene chloride at various temperatures. It was found that only one kind of binary complex is detectable in the methacrylonitrile–ethylaluminum dichloride equimolar mixture, while in nonequimolar systems there are several kinds of binary complexes, depending on the molar ratio at low temperature in these solvents. Moreover, the chemical shifts of the protons of methacrylonitrile due to complex formation with ethylaluminum dichloride show a remarkable temperature dependence in toluene, but not in methylene chloride. This fact can be interpreted by an assumption of the formation of a ternary complex of methacrylonitrile, ethylaluminum dichloride, and aromatic donor molecules, mainly due to the dipole interaction between the nitrile group complexed with ethylaluminum dichloride and aromatic donor. The orientation of toluene molecules in the ternary complex of methacrylonitrile or methyl methacrylate is discussed.
Physical properties of some low polymer content radiation‐grafted wool copolymers
Authors: McLaren K. G. , Watt I. C.
Published: April 2003

Wool copolymers with low polymer content (6–18%) have been prepared by radiation grafting techniques. Supercontraction, density, and formic acid vapor sorption measurements have been used to assess changes in the keratin structure produced by the grafting processes. Kinetic studies of the contractile forces developed in the first (reversible) stage of the supercontraction of wool in lithium bromide showed that grafting with poly(N‐methylol acrylamide) or polyacrylonitrile has a “repairing” action which offsets changes in the wool structure produced by the small radiation dose (2 Mrad) used for the grafting process. By contrast, grafting with poly(vinyl acetate) had no repairing effect. The bonds formed by grafting of poly(N‐methylol acrylamide) or polyacrylonitrile to keratin do not reduce swelling of the wool by formic acid, which is a measure of effective crosslink density. Grafting with poly(vinyl acetate) led to increased swelling by formic acid, indicating some disruption of the keratin structure during polymerization. It is suggested that the role of the grafted polymer is mainly to stabilize the hydrogen‐bonded secondary network by interaction between the polypeptide and polymer chains.
Polymerization of coordinated monomers. X. Kinetic study of alternating copolymerization of methyl methacrylate and styrene with stannic chloride in dichloroethane
Authors: Komiyama Makoto , Hirai Hidefumi
Published: April 2003

The alternating copolymerization of methyl methacrylate with styrene with the use of stannic chloride was kinetically examined at −20°C in 1,2‐dichloroethane both under photoirradiation and with radical initiator (2:1 tri‐n‐butylboron‐benzoyl peroxide system). At conversions lower than 7%, the conversion increases linearly to the polymerization time, whereas the degree of polymerization is constant irrespective of the polymerization time. The alternating copolymerizations are 1.5 order and the 1.0 order reactions with respect to the ternary molecular complex composed of stannic chloride, methyl methacrylate, and styrene, under photoirradiation and with initiator, respectively. The linear dependences of the rates upon the 0.5 order of the intensity of the incident light and upon the 1.0 order of the concentration of tri‐n‐butylboron indicate a bimolecular termination. The rate normalized by the 1.5 order of the concentration of the coordinated methyl methacrylate and the rate normalized by the concentration of the coordinated methyl methacrylate are proportional to the 1.5 and 1.0 orders of the charged concentration of styrene, for the copolymerizations under photoirradiation and with initiator, respectively. The kinetic results in the 1,2‐dichloroethane solution are quite consistent with those in the toluene solution. The alternating copolymerization mechanism, in which the ternary molecular complex predominantly homopolymerizes as a monomer unit, is confirmed.
Interaction between dyes and polyelectrolytes. I. Effect of polyelectrolytes on the reaction of methylene blue with 1‐benzyl‐1,4‐dihydronicotinamide
Authors: Shirai Masamitsu , Tanaka Makoto
Published: April 2003

The effect of polyelectrolytes on the reaction of methylene blue with 1‐benzyl‐1,4‐dihydronicotinamide was investigated. An accelerating effect was observed on addition of sodium polystyrenesulfonate of poly(potassium p‐styrenesulfonate). On the other hand, deceleration was observed on addition of potassium polyvinylsulfate. No appreciable effect was observed when sodium p‐toluenesulfonate or potassium chloride was used as an electrolyte. An obvious color change was observed when methylene blue is bound to these anionic polyelectrolytes. Some correlations with spectral change of methylene blue and acceleration or deceleration effect are discussed.
Structure of chlorinated poly(vinyl chloride). III. Preparation of poly(vinyl chloride)‐β,β‐d2 as a model for the study of the mechanism of chlorination and of the chlorinated poly(vinyl chloride) structure
Authors: Lukáš R. , Kolínský M.
Published: April 2003

A method for the preparation of poly(vinyl chloride)‐β,β‐d2 (PVC‐β,β‐d 2) as a model for the investigation of the mechanism of chlorination and of the CPVC structure has been suggested. The conditions of preparation of deuterated intermediates of a multistage synthesis of vinyl chloride‐β,β‐d2 and of suspension‐polymerized PVC‐β,β‐d2 have been described including the mass balance. Malonic acid was used as the starting compound. Tacticity values of a sample of PVC‐β,β‐d2 and its infrared and NMR spectra are presented and compared with data already published.
A new type of photodegradable polymer having a pyrazine moiety in the chain
Authors: Sakuragi Masako , Hasegawa Masaki , Nishigaki Masahiko
Published: April 2003

Photooxidative degradation of poly‐2,5‐distyrylpyrazine (poly‐DSP) has been studied in detail. Both amorphous poly‐DSP film and poly‐DSP solution were photooxygenated and degraded by irradiation by sunlight in the air. The nitrile group was formed, together with carbonyl groups and hydroxyl group. The photodegradation of a pyrazine derivative to a nitrile derivative is a new reaction. Next, photodegradation behavior of polymers having a cyclobutane moiety in the main chain, poly‐1,4‐bis[2‐(2‐pyridyl)‐vinyl]benzene (poly‐P2VB) and polydiethyl p‐phenylenediacrylate (poly‐p‐PDA Et), was studied. The photodegradability of these polymers decreases in the order: poly‐DSP > poly‐P2VB ≫ poly‐p‐PDA Et. Further, the photodegradation behavior of various vinyl polymers containing a vinylpyrazine or vinylpyridine component and polyamides having pyrazine or pyridine ring in the main chain, was investigated. Of these, polyvinylpyrazine has the largest photodegradability.