bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of pyridine on the kinetics of polymerization of methyl methacrylate initiated by benzoyl peroxide and azobisisobutyronitrile at 60°C
Authors: Ghosh P. , Mukhopadhyay G. 
Published: April 2003

AbstractSolution polymerization of MMA, with pyridine as the solvent and BZ2O2 and AIBN as thermal initiators, was studied kinetically at 60°C. The monomer exponent varied from 0.45 to 0.91 as [BZ2O2] was increased from 1 × 10−2 to 30 × 10−2 mole/liter in a concentration range of 8.3‐4.6 mole/liter for MMA. For AIBN‐initiated polymerization the monomer exponent remained constant at 0.69 as [AIBN] varied from 0.4 × 10−2 to 1.0 × 10−2 mole/liter in the same concentration range for MMA. The k2p/kt Value increased in both cases with an increase in pyridine concentration in the system. This was explained in terms of an increase in the kp value, which was due presumably to the increased reactivity of the chain radicals by donor‐acceptor interaction between the molecules of solvent pyridine and propagating PMMA radicals and in terms of lowering the kt value for the diffusion‐controlled termination reaction due to an increase in the medium viscosity and pyridine content.
Reaction of polyurethane foam with dry steam: Kinetics and mechanism of reactions
Authors: Gerlock J. L. , Braslaw J. , Mahoney L. R. , Ferris F. C. 
Published: April 2003

AbstractThe reaction of a polyether‐based polyurethane foam with dry atmospheric pressure steam was examined as one approach to waste polyurethane foam recovery. Complete reaction at temperatures between 190 and 230°C yielded high‐quality polyol, isomeric toluenediamines, and carbon dioxide as primary products. Kinetic analysis of toluenediamine yields versus time suggested the occurrence of a parallel first‐order reaction scheme wherein urethane linkages react up to 50 times faster than urea linkages. The results derived from kinetic experiments and ancillary thermochemical and spectroscopic studies indicated that urethane linkages are broken by direct hydrolysis, whereas urea linkages undergo thermal dissociation to parent isocyanate and amine. Subsequent rapid hydrolysis of the isocyanate produced was necessary to obtain high yields of toluenediamine products. The rate of the slower reaction, dissociation of urea linkages, can be enhanced by a factor of 20 by the addition of trace amounts of sodium hydroxide to the foam.
An analysis of the substitution effects involved in diepoxide‐diamine copolymerization reactions
Authors: Charlesworth John 
Published: April 2003

AbstractThe relative reactivity of the functional groups present in aromatic amine and diepoxide monomers has been investigated by gel permeation chromatography. The ratio of rate constants for the consumption of the secondary and primary amine hydrogens involved in the reaction between aniline and phenyl glycidyl ether has been calculated to equal approximately 0.5. In the case of the reaction between N‐methy aniline and diglycidyl ether of bisphenol A (DGEBA) the rate constant ratio for the consumption of the first and second epoxide groups in the DGEBA molecule is also approximately 0.5. In contradiction to previously published data these results suggest that substitution effects are unimportant for aromatic amines as well as DGEBA. Furthermore, etherification side reactions, consuming epoxide groups at the expense of the amine–epoxide reaction, also appear to be insignificant.
Anionic polymerization with alkaline earth counterion. III. Aging of oligo‐ and polystyryl‐barium and ‐strontium in THF
Authors: Mathis Claude , Christmann‐Lamande Lydia , Francois Bernard 
Published: April 2003

AbstractThe self‐deactivation of polystyryl‐barium and polystyryl‐strontium in tetrahydrofuran (THF) results essentially from protonation by the solvent. The deactivation constant kd of this reaction is independent of carbanion concentration, length, and functionality of chains. Relations of kd with temperature are: polystyryl‐barium: kd = 6.25 × 107 exp(‐18,900/RT) sec−1; polystyryl‐strontium: kd = 4.1 × 106 exp(−16,000/RT) sec−1. The self‐deactivation of α,ω‐dicarbanionic oligostyryl‐barium is a nonrandomlike reaction. Residual living oligomers are left dicarbanionic even if an important deactivation occurs.
The transacetalization reaction during the etherification of poly(oxymethylene)diol [α‐hydro‐ω‐hydroxypoly(oxymethylene)] with orthoesters in the presence of lewis acids
Authors: Colombo Paolo , Custro Sergio , Radici Pierino 
Published: April 2003

AbstractA transacetalization reaction occurs during the etherification of poly(oxymethylene)diol [α‐hydro‐ω‐hydroxypoly(oxymethylene)] with orthoesters and an important modification of molecular structure takes place. The intermediates formed during the transacetalization reaction are emphasized. The connection between this reaction and the other reactions during the etherification of poly(oxymethylene)diols is discussed.
Evaluation of polymerization rate by chain length dependence on polymer–polymer termination and primary radical termination in radical polymerization
Authors: Ito Katsukiyo 
Published: April 2003

AbstractIn order to analyze the polymerization rate at high initiation rate and/or low monomer concentration, the rate equations are derived by a rate formulated previously for polymer–polymer termination and another rate for primary radical termination, which is formulated here (both rates depend on chain length of polymer radical). Such equations would be applicable to the kinetic data in the polymerizations of styrene and methyl methacrylate. This shows that the assumption that both rates are independent of chain length overestimates the rate of primary radical termination.
Investigation of cationic copolymerization of styrene with p‐benzoquinone
Authors: Ragimov A. V. , Nagiev A. Yu. , Liogonky B. I. , Berlin A. A. 
Published: April 2003

AbstractThe kinetics of copolymerization of styrene with p‐benzoquinone in the presence of BF3OEt2 is investigated. The rate constants and activation energy of the copolymerization process are determined. The reaction orders for monomer and catalyst are estimated. It is found that the rate of styrene and quinone copolymerization increase and the induction period decreases owing to addition of the latter. It is shown that the copolymerization rate achieves its maximum at an equimolal ratio of monomers. This phenomenon is explained by formation of active molecular complex between styrene and p‐benzoquinone. On the basis of obtained data the course of copolymerization is interpreted and the cationic mechanism of copolymerization process is proposed.
Polymerization of methyl methacrylate initiated by oligoglycine, water, cupric ion, and carbon tetrachloride
Authors: Ree Keiu , Kawasaki Hiroshi , Minoura Yuji 
Published: April 2003

AbstractThe polymerization of methyl methacrylate (MMA) was carried out in the presence of oligoglycines (glycine, its dimer, trimer, tetramer, etc.), water, cupric ions, and carbon tetrachloride. It was found that poly‐MMA is formed in the water layer and that the system using triglycine gives the maximum polymer yield. On the effect of pH of water layer, the rate of polymerization is faster in the alkalic condition (pH 8–10) than in normal condition (pH 3.8), while in the acidic media (pH 2–3), the rate is not accelerated. From the results of kinetic studies, the polymerization rate is dependent on the 0.5 power of the amount of diglycine or cupric ion, and it is independent of the amount of MMA. The polymerization mechanism was discussed.
Effect of sovents on radiation‐induced ionic graft polymerization
Authors: Kabanov V. Ya. , Aliev R. E. , Sidorova L. P. 
Published: April 2003

AbstractThe influence of various solvents on radiation‐induced cationic (grafting of vinyl‐n‐butyl ether onto polyethylene) and anionic (grafting of 2‐methyl‐5‐vinylpyridine onto polyethylene) graft polymerization was studied. This ionic grafting was performed in thoroughly dried systems at room temperature. It was established that electron‐acceptor solvents promote cationic grafting but that electron‐donor solvents promote the anionic. A clear correlation between the donor number of solvents and grafting value by the anionic mechanism was shown. There was no correlation between dielectric constants and grafting values. The reaction orders, according to monomer concentration by 2‐methyl‐5‐vinylpyridine grafting in various solvents, were equal to approximately 1.5 and 2 for the radical and anionic mechanisms, respectively. The effect of solvents on radiation‐induced ionic graft polymerization is discussed. The results of this study indicate the correct choice of solvents for radiation‐induced ionic grafting.
Functional polymers. III. Asymmetric Michael reactions catalyzed by cinchona alkaloid–acrylonitrile copolymers
Authors: Kobayashi Norio , Iwai Kiyoko 
Published: April 2003

AbstractThe enantio‐differentiating abilities of cinchona alkaloid–acrylonitrile copolymers (AN–CA) in the Michael reactions were studied. The reaction of methyl indan‐1‐one‐2‐carboxylate (I) with methyl vinyl ketone in toluene at room temperature yielded product (II) in 24–42% optical yield, depending on the type and frequency of the alkaloid units on the polymeric skeleton. The catalysts were recovered from the reaction mixture by filtration and with retention of their stereoselectivities. Modification of the amino or hydroxyl group of the alkaloid moiety greatly reduced the reaction rate and optical yield. The asymmetric reactions of other donors (III–VII) with methyl vinyl ketone were also studied.
Effect of cyclobutane carbonitrile rings on the glass transition temperature of vinyl copolymers
Authors: Collette J. W. , Gale D. M. , Belletete M. G. 
Published: April 2003

AbstractA wide compositional range of copolymers of 1‐cyclobutene carbonitrile (CBCN) and 1‐bicyclobutance carbonitrile (BBCN) with common vinyl monomers was prepared in order to study systematically the effect of cyclobutane carbonitrile ring incorporation on the glass transition temperature (Tg). In general, the Tg's of the copolymers are increased in proportion to the weight percent of the small‐ring monomer incorporated, but the 1,2‐mode of incorporation raises Tg more than the 1,3‐mode. Attempts were made to correlate data with quantitative Tg–composition relationships (Fox–Johnston equations). Prediction for nitrile homopolymer Tg's are compared with literature values.
Reactions of stabilizer compounds. III. Oxidative reactions of some 2′‐hydroxy‐2‐phenylbenzotriazole light stabilizers in the AIBN‐initiated autoxidation of cumene
Authors: Hodgeman Daryl K. C. , Gellert Evan P. 
Published: April 2003

AbstractOxidative decay of number of commercially important 2′‐hydroxy‐2‐phenylbenzotriazole light stabilizers during the AIBN‐initiated autoxidation of cumene at 65°C is described. The reactivity of the hydroxyphenylbenzotriazoles studied increased in the order 2‐(2′‐hydroxy‐5′‐methyl)phenylbenzotriazole (Ia) < 2‐(2′‐hydroxy‐3′,5′ ‐di‐tert‐pentyl)phenylbenzotriazole (Ie) < 5‐chloro‐2‐(3′,5′‐di‐tert‐butyl‐2′‐hydroxy)phenylbenzotriazole (Ic) < 5‐chloro‐2‐(3′‐tert‐butyl‐2′‐hydroxy‐5′‐methyl)phenylbenzotriazole (Ib). The major product from the reaction of Ib was identified as the cumylperoxycyclohexa‐2,5‐dienone (III). The possible occurrence of these reactions during the degradation of stabilized polymers is discussed.
Determination of initiation rate of copolymerization of acrylonitrile with p‐bromophenyl acrylate carried out in N,N‐dimethylformamide
Authors: Miller Andrzej , Szafko Jerzy 
Published: April 2003

AbstractStudies of the initiation rate of the copolymerization reaction of acrylonitrile with p‐bromophenyl acrylate initiated by azobisisobutyronitrile in dimethylformamide at 60°C are reported. The inhibition method involved use of stable Banfield's radical (N‐[1,1‐dimethyl 3‐(N‐oxidophenylimine)butyl]‐N‐phenylaminyl oxide). In the case of acrylonitrile, a side reaction effect of the initiation with the stable radical was observed along with a retarding effect resulting from inhibition reaction products (2kdf) = 8.2 × 10−4 min−1. During the inhibited homopolymerization of p‐bromophenyl acrylate a very strong side initiation reaction effect results from the Banfield radical; the inhibition reaction products do not influence the further course of the polymerization reaction. Side initiation effects of the Banfield radical (BR) increase with increasing concentration of p‐bromophenyl acrylate. The overall contribution of the side initiation reaction changes for different comonomer mixtures; with their compositions the actual changes are nonadditive. The inhibition reaction products do not influence the further course of copolymerization. The initiation rate in monomer mixtures depends on their composition and may be described by the following relation:
Model for predicting the composition of copolyesters: Polymerization of terephthalic acid, 2,2′‐oxydiethanol, and 2,2‐dimethyl‐1,3‐propanediol
Authors: Sandhu M. A. , Fields R. D. 
Published: April 2003

AbstractCopolyesters of two glycols and a dicarboxylic acid moiety are frequently made to obtain specific physical properties. In the synthesis of these polymers an excess of glycol is used in the ester‐exchange reaction and then removed during the polycondensation reaction to form a high‐molecular‐weight product. A model has been developed to predict the final polymer composition. The derivation is based on equilibria of reaction species (free glycol, polymer chain ends, and ester links) and the relative vapor pressures of the two reacting glycols. Calculated results are compared with experimental results of poly(2,2′‐oxydiethylene: 2,2‐dimethyl‐1,3‐propylene terephthalate)s. There is good agreement between calculated and experimental compositions. The model can be used to calculate the glycol concentrations that must be used to make a specific polymer composition. This model should also be useful in the calculation of other mole ratios of glycol to dicarboxylic acid that will make the same composition.
Kinetics of radical polymerization. XXX. Polymerization of styrene in solution
Authors: Földes‐Berezsnich T. , Szesztay M. , Boros‐Gyevi E. , TüdöS F. 
Published: April 2003

AbstractA study was made on the AIBN‐initiated polymerization of styrene in benzene and dimethyl formamide at 50°C. The overall rate and the rate of initiation of the polymerization were determined and the number‐average and weight‐average molecular weights of the polymers formed were measured. The decrease in the rate and degree of polymerization with the decrease in styrene concentration was caused by the corresponding decreases in the rate constants of chain propagation and initiation steps. In the systems studied no chain transfer process occurred with an experimentally measurable rate.
Determination of sulfate and similar end groups in polymers [poly(methyl methacrylate) and polystyrene] by an improved dye interaction method
Authors: Chaudhuri Arindam , Palit Santi R. 
Published: April 2003

AbstractIt has been observed that in a benzene medium the carbinol base of a cationic dye reacts with a polymer with SO3 Na and similar end groups that give rise to a reversible color formation of the dye cation. This reaction can be pushed to completion and consequent intensification of color by adding a benzene‐insoluble acid such as citric acid. This principle has been applied to develop an improved dye interaction method of determining such end groups. The end groups values thus obtained by this method for different poly(methyl methacrylate) and polystyrene samples were found to be in fairly good agreement with those obtained by the dye partition (extrapolation) method.
Photosensitized degradation of polyethylene glycols in aqueous solutions. I. Viscosimetric measurements
Authors: Augustyniak Wlodzimierz , Wojtczak Jan 
Published: April 2003

AbstractInvestigations were performed on acetone and benzene‐sensitized degradation of triethylene glycol (TEG), polyethylene glycol 400 (PEG 400), and polyethylene glycol 4000 (PEG 4000) in aqueous solutions exposed to irradiation at λ = 254 nm and λ ∼ 313 nm. The systems investigated were exposed at 20°C (±1°C) in both deaerated and undeaerated solutions. The course of the photosensitized degradation was examined viscosimetrically. The determined quantum yield (ϕ) of chain scission decreases distinctly as the molecular weight of the polymer rises, irrespective of the wavelength of the light absorbed and deaeration of system exposed.
Effect of solvent on the copolymerization of ethylene and vinyl acetate
Authors: Van Der Meer R. , Aarts M. W. A. M. , German A. L. 
Published: April 2003

AbstractThe ethylene (M1)–vinyl acetate (M2) copolymerization at 62°C and 35 kg/cm2 with α,α′‐azo‐bisisobutyronitrile as initiator has been studied in four different solvents, viz., tert‐butyl alcohol, isopropyl alcohol, benzene, and N,N‐dimethylformamide. The experimental method used was based on frequent measurement of the composition of the reaction mixture throughout the copolymerization reaction by means of quantitative gas chromatographic analysis. Highly accurate monomer reactivity ratios have been calculated by means of the curve‐fitting I procedure. The observed dependence of the r values on the nature of the solvent is surprisingly large and can be correlated with the volume changes (= excess volumes) observed on mixing vinyl acetate (VAc) with the relevant solvent. An increased hydrogen bonding or dipole–dipole interaction through the carbonyl moiety of the acetate side group of VAc, induces a decreased electron density on the vinyl group of VAc, which in turn leads to a decreased VAc reactivity. The differences among the overall rates of copolymerization in the various solvents can be interpreted in terms of a variable chain transfer to solvent and the rate of the subsequent reinitiation by the solvent radical. In the case of benzene, complex formation is believed to play an important part.
Effect of polyion conformation on dye binding. V. Induced optical activity of acridine orange bound to a synthetic nonstereoregular polyelectrolyte
Authors: Beaumais J. , Fenyo J. C. , Muller G. 
Published: April 2003

AbstractIt is shown that the induced Cotton effects in the visible region of the absorption bands of acridine orange in the presence of a nonstereoregular α‐carboxylic polysulfonamide (PLL) can be attributed to stacked bound dye molecules, irrespective of the conformation of the polymer. The existence of an ordered structure seems to be unnecessary for such an induction.
The study of macronet isoporous styrene polymers by gel permeation chromatography
Authors: Tsyurupa M. P. , Davankov V. A. 
Published: April 2003

AbstractGel permeation chromatography was used for studying the structure of macronet isoporous styrene polymers swollen in chloroform. The polymers were obtained by crosslinking polystyrene either in a solution or in a swollen state using monochlorodimethyl ether and p‐xylylenedichloride via the Friedel–Crafts reaction. It is shown that the networks obtained by structurization of concentrated polystyrene solution in a good solvent are characterized by loose structure, fine pores (ca. 10 Å), and narrow pore distribution. In poor solvents or in strong dilution of polystyrene and at the instant of net formation, the polymers that are obtained contain, in addition to fine pores, large pores with diameters up to 300 Å.
Fibrillar aggregation in cotton cellulose subjected to multiple swelling treatments with alkali
Authors: Manjunath B. R. , Venkataraman A. 
Published: April 2003

AbstractThe role of aqueous alkali solutions as swelling agents of cotton cellulose has been studied by various workers and these reagents have been invariably considered to cause lattice disorder in cellulose. The effect of multiple swelling treatments on the cotton cellulose structure has not been studied hitherto. The present study on cotton demonstrates that is the concentration of the swelling agents and the conditions at the time of treatment which determine the resultant order in the final product. The resultant lattice order so attained is shown to be far in excess of any observed in either native or regenerated celluloses or even their hydrolyzed products, with complete retention of their fibrous form. X‐ray diffraction and electron microscopy data show conclusively that fibrillar “aggregation” or their “dispersion” can be effectively controlled and are the results of the soda cellulose complexes which form upon alkali treatments. The role of water vis‐á‐vis the formation of cellulose II is extensively discussed. Studies on sorption and tensile properties of the treated samples lend support to the phenomenon of fibrillar aggregation in cellulosic fibers.
Some electrical properties of wood pulp treated with sodium hydroxide
Authors: Hanna A. A. , Ibrahem Atef A. , Heikal Salwa O. 
Published: April 2003

AbstractThe effect of the degree of crystallinity and degree of polymerization on the electrical properties of soda‐treated wood pulp has been investigated. The dielectric constant (E′) and the dielectric loss (E″) were measured for the treated samples over a frequency band 0.2–10 MHz at 20°C. Also, the electrical conductivity (σ) was calculated from the measured data of the dielectric constant. From the results obtained we found that the degree of crystallinity and the degree of polymerization decrease with time of oxidation while the number of carboxylic groups increased. E″,E′, and σ were found to increase with the decrease in the degree of crystallinity.
New processable poly(ether‐keto‐sulfone)s, poly(arylene sulfone)s, and polyesters curable by intramolecular cyclization. XVII
Authors: Somers A. , Marvel C. S. 
Published: April 2003

AbstractNew processable polyaromatic ether‐keto‐sulfones were prepared from 2,2′‐diiododiphenyl‐4,4′‐dicarbonyl dichloride (I), bis(p‐phenoxybenzene)sulfone (V), isophthaloyl chloride (VI), terephthaloyl chloride (VII), and diphenylether (IX) in Friedel‐Crafts‐type polymerizations. By varying (VI):(VII) ratio and (V):(IX) ratio and by reducing the polymerization time, soluble, processable polymers were obtained. In these polymers, phenylacetylenyl groups were introduced by replacing the iodine. This process led to soluble and curable polymers. Transparent, tough films and fairly flexible glass fiber laminates can readily be prepared. After curing, the polymers were insoluble and showed excellent chemical and thermal resistance. The curing process increased the polymers' softening temperature by ca. 20°C and produced intersting new useful materials for laminates. Processable poly(arylene sulfone)s were prepared from I, V, and diphenylether‐4,4′‐disulfonylchloride (X) in a Friedel‐Crafts‐type polymerization. Different monomer ratios and polymerization times were used. Only low‐molecular‐weight polymers were obtained. The same result was shown by curable polyester formation from I, VI, VII, and 4,4′‐sulfonyldiphenol (XI) in an interfacial polycondensation.
Polymerization of N‐vinylpyrrols
Authors: Trofimov B. A. , Minakova T. T. , Tandura T. A. , Mikhaleva A. I. , Korostova S. E. 
Published: April 2003

AbstractThe free polymerization of 2‐methyl‐1‐vinylpyrrol (I), 2,3‐dimethyl‐1‐vinylpyrrol (II), 1‐vinyl‐4,5,6,7‐tetrahydroindol (III), 1‐vinyl‐2‐phenylpyrrol (IV), and 1‐vinyl‐2‐phenyl‐5‐trifluoroacetyl pyrrol (V) in the presence of azobisisobutyronitrile as an initiator at 60–80°C has been studied. The polymer yield (up to 90%) and molecular weight in the range 2000–13,000 are strongly dependent on the monomer structure and the polymerization conditions. The reactivity of N‐vinylpyrrols studied falls in the order: I > III > II > V > IV implying an important role of the initial radical stabilization with the participation of the ring substituents as well as the steric hindrances in the propagation stage.