bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on tacticity of polyacrylonitrile. I. High‐resolution nuclear magnetic resonance spectra of polyacrylonitrile
Authors: Yamadera Reizo , Murano Masao 
Published: April 2003

AbstractThe nuclear magnetic resonance spectra of polyacrylonitriles prepared under various polymerization conditions were measured in NaCNS–D2O solution. The methylenic proton resonance could be separated into two triplets: one is due to the protons of the syndiotactic methylene groups and the other is due to the isotactic ones. The tacticity of polyacrylonitrile could be determined by the ratio of the integrated intensities of the two triplets. Polyacrylonitriles prepared with radical catalysts are approximately 75% syndiotactic, and polyacrylonitriles prepared by the anionic polymerization at low temperature, γ‐irradiation in the solid state, Mg molecular beam, and γ‐irradiation on the urea canal complex are more isotactic but have no remarkable stereoregularity.
Effects of metal salts on polymerization. Part III. Radical polymerizabilities and infrared spectra of vinylpyridines complexed with zinc and cadmium salts
Authors: Tazuke Shigeo , Okamura Seizo 
Published: April 2003

AbstractRadical polymerization of 4‐vinylpyridine (4‐VP), 2‐vinylpyridine (2‐VP), and 2‐methyl‐5‐vinylpyridine (MVP) was studied in concentrated DMF solutions of ZnCl2, ZnBr2, ZnI2, Zn(CH3COO)2, and Cd(CH2COO)2 at 50°C. Polymerization of 4‐VP and MVP was accelerated by the addition of the metal salts, while the polymerization of 2‐VP was greatly retarded. The sequence of the accelerating effect of metal salts for 4‐VP was in the following order: Cd(CH3COO)2 > ZnCl2 > Zn(CH3COO)2 > ZnBr2 > ZnI2. This sequence is almost the same as that reported in a previous report for MVP. However, the order was reversed for the retarding effect on the polymerization of 2‐VP. At the intermediate concentration of metal salts, polymerization of 4‐VP proceeded heterogeneously, which was explained by considering crosslinking of poly‐4‐VP by the metal ion. Since a linear correlation between the rate Rp and the degree of polymerization was observed for the 4‐VP–Zn(CH3COO)2 system, the accelerating effect was postulated to be due to the enhancement in kp. Results of copolymerization of VP with styrene as M2 in a concentrated solution of Zn(CH3COO)2 indicated the strong activation of 4‐VP by complex formation (r1 = 2.7 ± 0.5, r2 = 0.08 ± 0.03), whereas the change in the monomer reactivity of MVP is smaller (r1 = 2.0 ± 0.2, r2 = 0.35 ± 0.05). The behavior of 2‐VP was abnormal (r1 = 3.35 ± 0.3, r2 = 0.55 ± 0.15, then r1r2 > 1), which was attributed to the steric effect by complex formation. Solid complexes formed between pyridine, 4‐VP, 2‐VP, or MVP and zinc salts were prepared as samples for infrared spectroscopy. The shifts in infrared absorption bands of these amines were studied by comparing the infrared spectra of the amines before and after the complex formation, and the results were interpreted in terms of electronic as well as steric interactions of metal salts with ligands. Conjugation of the metal salt with the ligand π‐orbitals was necessary to explain both infrared spectra and polymerization results.
Applications of limiting conversion free‐radical polymerizations. II. Azobisisobutyronitrile‐initiated polymerization of methyl methacrylate in benzene
Authors: Indictor N. , Mogolesko P. , Jaffe H. 
Published: April 2003

AbstractData for the azobisisobutyronitrile‐initiated polymerization of methyl methacrylate in dilute benzene solution is presented at 80, 100, and 126°C. in terms of Tobolsky's limiting conversion kinetics. Number‐average molecular weights were obtained viscometrically. Attempts to evaluate the relative amounts of combination and disproportionation in the chain‐terminating reaction were foiled by the discovery that under the conditions reported the initiator efficiency is temperature‐dependent decreasing markedly with increasing temperature.
Homopolymerization of ethylene and copolymerization with 1‐butene in the presence of bis(cyclopentadienyl)titanium dichloride and diisobutylaluminum chloride
Authors: Rubin I. D. 
Published: April 2003

AbstractEthylene was homopolymerized and copolymerized with 1‐butene in benzene at 30°C. with the use of bis(cyclopentadienyl)titanium dichloride and diisobutylaluminum chloride as catalyst. Both freshly prepared catalyst and catalyst which had been aged up to 114 hr. were used. When the catalyst was aged prior to adding the monomer, the yields were lower and the products had higher molecular weights. In the case of copolymers, aging of the catalyst also affected the relative concentrations of the comonomers in the products. 1‐Butene was an effective chain transfer agent under all reaction conditions. The data were found to be consistent with the previously suggested mechanism according to which different species initiate polymerizations with freshly mixed and aged catalysts.
Stereoregularity of poly(vinyl ether)
Authors: Matsuzaki Kei , Hamada Minoru , Arita Koichiro 
Published: April 2003

Abstractα‐Methylvinyl isobutyl and methyl ethers were polymerized cationically and the structure of the polymers was studied by NMR. Poly(α‐methylvinyl methyl ether) polymerized with iodine or ferric chloride as catalyst was found to be almost atactic, whereas poly(α‐methylvinyl isobutyl ether) polymerized in toluene with BF3OEt2 or AlEt2Cl as catalyst was found to be isotactic. In both cases, the addition of polar solvent resulted in the increase of syndiotactic structure as is the case with polymerization of alkyl vinyl ether. tert‐Butyl vinyl ether was polymerized, and the polymer was converted into poly(vinyl acetate), the structure of which was studied by NMR. A nearly linear relationship between the optical density ratio D722/D736 in poly(tert‐butyl vinyl ether) and the isotacticity of the converted poly(vinyl acetate) was observed.
Reactivity ratios of styrene and methyl methacrylate at 90°C
Authors: Meyer Victor E. 
Published: April 2003

AbstractFrom the conversion–composition data of Gruber and Elias, the reactivity ratios of styrene (M1) and methyl methacrylate (M2) were calculated to be r1 = 0.55 ± 0.02 and r2 = 0.58 ± 0.06 at 90°C. The least‐squares method was then used on these and literature values at other temperatures to obtain the Arrhenius expressions: In r1 = 0.04736 – (235.45/T), and ln r2 = 0.1183 – (285.36/T). Using literature values for the homopolymerization steps, A11 = 2.2 × 107l./mole‐sec., E11 = 7.8 kcal./mole, and A22 = 0.51 × 107 l./mole‐sec.−1, E22 = 6.3 kcal./mole, activation energies and frequency factors were then calculated for the cross‐polymerization steps: A12 = 2.1 × 107 l./mole‐sec., E12 = 7.3 kcal./mole, and A21 = 0.45 × 107 l./mole‐sec., E21 = 5.7 kcal./mole.
Kinetics and mechanism of acrylonitrile polymerization by p‐toluenesulfinic acid. II. Polymerization mechanism
Authors: Amdur S. , Shavit N. 
Published: April 2003

AbstractThe retardation of acrylonitrile (AN) polymerization by p‐toluenesulfinic acid (TSA) in the presence of relatively strong acids has been further investigated. Conductance measurements supported the hypothesis that an ionic complex, presumably RSO2H2+, is obtained by a reaction of the sulfinic acid with a proton. It is postulated that this complex is a chain transfer agent for the observed retardation. On the basis of this assumption, a kinetic scheme was developed involving additional termination steps by the complex. The scheme accounts for the maximum in initial rate observed on increasing the concentration of added sulfonic acid at a constant TSA concentration. It also provides an explanation for the elimination of the autoacceleration in the bulk polymerization of AN when strong acids are added. The orders derived from the kinetic equations are in good agreement with the orders evaluated from the kinetic experiments.
Kinetics and mechanism of acrylonitrile polymerization by p‐toluenesulfinic acid. III. Initiation through disproportionation
Authors: Amdur Shimon , Shavit Nehemia 
Published: April 2003

AbstractA mechanism for radical formation from aromatic sulfinic acids through the disproportionation reaction is suggested. It is postulated that two parallel steps, one a bimolecular reaction and the other involving a trimer of sulfinic acid, yield sulfenyl sulfonate. This labile compound decomposes into free radicals or reacts with another molecule of sulfinic acid producing thiol sulfonate and sulfonic acid. This mechanism explains the variety and unusually high orders encountered in polymerization initiated by sulfinic acid initiators. The proposed kinetic scheme is in agreement with the proton dependence found for both the initiation as well as the disproportionation reactions.
Diffusion in ethylene–propylene rubber
Authors: Laurence R. L. , Slattery J. C. 
Published: April 2003

AbstractA study of sorption in a copolymer of ethylene and propylene is presented. Long‐time sorption and desorption measurements provided the actual diffusion coefficient in the limit of zero concentration gradient. An analysis of the diffusion–sorption data reinforced the Frisch hypothesis about diffusion in a polymer matrix. The better solvent deforms the microstructure, allowing a more marked dependence of the diffusivity upon concentration.
Radiation‐induced bulk polymerization of maleimide
Authors: Kagiya Tsutomu , Izu Masatsugu , Kawai Shunzo , Fukui Kenichi 
Published: April 2003

AbstractRadiation‐induced bulk polymerization of maleimide in both solid and liquid states was studied. Benzoquinone inhibited the liquid‐state polymerization and retarded solid‐state polymerization. The results of ESR study showed that solid monomer irradiated at 61°C. gave a spectrum, the concentration of which slowly decreased without changing the shape at 61°C. The radical detected at 61°C. was shown not to be the main propagating species. Overall rate polymerizations in the liquid and solid states were expressed, respectively, by first‐order and zero‐order rate equations with respect to the concentration of monomer. The overall rate constants in liquid and solid states were proportional to I0.9 and I1.0, respectively.
Environmental effects in free‐radical polymerizations. Part III. Vinyl chloride and n‐butyraldehyde
Authors: Burnett G. M. , Ross F. L. , Hay J. N. 
Published: April 2003

AbstractThe properties of poly(vinyl chloride) samples prepared by a free‐radical process in the presence of n‐butyraldehyde have been studied from the point of view of polymer tacticity, branching, molecular weight, and relative crystallinity. The postulate of a polymer radical–aldehyde complex, invoked to explain the increased crystallinity, was tested. The polymers had a lower degree of polymerization and branching than normal, and these parameters rather than increased syndiotacticity were responsible for the high degree of crystallinity. Both molecular weight and branching affect the crystallinity, since polymer samples prepared in the presence of various transfer agents with similar molecular weights were less crystalline than those prepared in aldehyde, but yet more crystalline than high molecular weight bulk polymer. Polymers prepared in aldehyde had a lower degree of branching than those formed in other transfer agents. It was concluded that aldehyde was effective in increasing the crystallinity of poly(vinyl chloride) in these two ways, and so appeared to be unique among the transfer agents. There was no evidence for assuming any complexing between polymer radicals and aldehyde.
Polymers of the vinyl esters of perchlorocyclopentadiene adducts of petroselinic and oleic acids
Authors: Liepins R. , Marvel C. S. , Lyon C. K. 
Published: April 2003

AbstractHomopolymers of vinyl 5‐(1,4,5,6,7,7‐hexachloro‐3‐undecylbicyclo [2.2.1]5‐hepten‐2‐yl)‐pentanoate and vinyl 8‐(1,4,5,6,7,7‐hexachloro‐3‐octylbicyclo [2.2.1]5‐hepten‐2‐yl)‐octanoate were prepared, as well as their copolymers with a vinyl tetrahydroabietate—tetrahydropimarate mixture, vinyl 12‐hydroxystearate, and vinyl chloride. The vinyl octanoate—12‐hydroxystearate copolymer gave light‐weight urethane foams with practically no volume change upon humid aging. The vinyl pentanoate and vinyl octanoate monomers lose hydrogen chloride during polymerization. The vinyl pentanoate homopolymer was hydrolyzed in an attempt to establish the position of the loss of hydrogen chloride. Fractionation of vinyl chloride copolymers of the vinyl petanoate and the vinyl octanoate derivatives showed that they possessed a rather homogeneous composition. Incorporation of the vinyl pentanoate monomer in a poly(vinyl chloride) copolymer imparted some internal plasticization with serious loss of tensile strength.
Kinetics of the bulk polymerization of dioxolane in the presence of water
Authors: Kučera Miloslav , Hladký Eduard , Majerová Karla 
Published: April 2003

AbstractThe polymerization of dioxolane initiated by the ∼Si⊕HSO ion pair is greatly influenced by water which changes the overall polymerization rate. Particularly great changes are brought about at certain higher conversions (whose values are also a function of an initial concentration of water). The polymerization practically stops at these conversions and the system appears to be close to a monomer—polymer equilibrium. It is shown that the equation Voverall = f([H2O]), which describes the dependence of the overall rate of polymerization on the concentration of water and which was originally derived for the polymerization of trioxane, holds also for the polymerization of dioxolane. The decrease of water concentration during the polymerization was measured and the observed equilibrium was shown to be a kinetic phenomenon.
Copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2
Authors: Higashimura T. , Tanaka A. , Miki T. , Okamura S. 
Published: April 2003

AbstractThe copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2 was studied at 30°C. to determine whether a cyclic monomer can copolymerize with a vinyl monomer. The formation of the copolymer was confirmed by elementary analysis of both benzene‐soluble and benzene‐insoluble fractions of the polymer obtained. It was found by gas chromatography that a fairly large amount of 4‐phenyl‐1,3‐dioxane and a small amount of trioxane were formed in the present system, in addition to polymers. Roughly a third of the total amount of the monomers reacted was consumed in the formation of methanol‐insoluble polymer, a third for 4‐phenyl‐1,3‐dioxane, and another third for trioxane and unknown products which could not be indentified. The formation of these cyclic compounds during the copolymerization may be explained in terms of a back‐biting (or intramolecular transacetalization) reaction. The cationic reactivity of tetraoxane was found to be similar to that of styrene on the basis of both the consumption rate of each monomer in the copolymerizing system and the composition of the methanol‐insoluble polymer obtained.
Cyclopolymerization of diallylamine derivatives in dimethyl sulfoxide
Authors: Negi Youji , Harada Susumu , Ishizuka Osamu 
Published: April 2003

AbstractDiallyl quaternary ammonium chlorides, bromides and N‐alkyldiallylamine hydrochlorides were polymerized with ammonium persulfate (APS) in dimethyl sulfoxide (DMSO). The dependences of yield and molecular weight of polymers on polymerization conditions were examined and quaternary ammonium chlorides were found to have better polymerizability than bromides. The poly(diallyl quaternary ammonium chlorides) obtained with APS—DMSO system are expected to have quite high molecular weights, as determined from the measurement of limiting viscosity numbers of the polymers in NaCl aqueous solution.
The polymerization of styrene oxide by the triisobutylaluminum–water system
Authors: Stille J. K. , Hillman J. J. 
Published: April 2003

AbstractStyrene oxide has been polymerized by the triisobutylaluminum–water catalyst system. Kinetic studies of the effects of varying the monomer, triisobutylaluminum, and water concentrations in benzene solutions have been made. Styrene oxide was consumed in two reactions: an initial fast one producing trimer and a slower reaction forming higher molecular weight polymer.
Cyclopolymerization of diastereomeric diepoxides
Authors: Stille J. K. , Hillman J. J. 
Published: April 2003

AbstractThe meso‐ and d,l‐diastereomers of o‐bis(epoxyethyl)benzene have been synthesized and identified. The diastereomers were polymerized by a variety of catalysts to give a polymer which has mainly isochroman recurring units as a result of a cyclopolymerization mechanism. Some features of the polymerization with the triisobutylaluminum catalyst system have been studied. The rates of polymerization of the monomers and the transition temperatures of the resulting polymers have been determined. The results are explained on the basis of a controlled intramolecular propagation and a stereospecific polymerization.
Catalysts for asymmetric‐induction polymerization of benzofuran. II. Properties and catalyses of some binary systems containing the menthoxy group
Authors: Hayakawa Yoshihiro , Fueno Takayuki , Furukawa Junji 
Published: April 2003

AbstractIt has been found that the equimolar binary system consisting of aluminum trichloride and (−)‐menthoxytriethyltin, ‐germanium or ‐silicone is effective for the asymmetric‐induction polymerization of benzofuran in toluene at −78°C. The specific rotation [α]D of the resultant polybenzofuran ranged from +10° to +40°, depending on the polymerization conditions as well as the metal atoms constituting the menthoxy compounds. The 1:1 ethylaluminum dichloride—menthol system was also effective for the same polymerization. It was confirmed that these binary systems easily undergo an exchange reaction, giving a dimeric menthoxyaluminum dichloride, (Men*OAlCl2)2, m.p. 72–75°C. A toluene solution of the crystalline dimer polymerized benzofuran into a high polymer having as large an [α]D value as +79.4°, although polymerization with the dimer was much slower than that with the parent binary mixtures. All these results lead to the conclusion that the true catalytic species of our multicomponent systems is most probably the dimeric menthoxyaluminum dichloride.
Ring‐opening polymerization of unsaturated alicyclic compounds
Authors: Calderon Nissim , Ofstead Eilert A. , Judy W. Allen 
Published: April 2003

AbstractThe ring‐opening polymerizations of cyclooctene, cyclododecene, 1,5‐cyclooctadiene, 1,5,9‐cyclododecatriene, 3‐methylcyclooctene, and 3‐phenylcyclooctene have been carried out by using a two‐component catalyst system composed of ethylaluminum dichloride and tungsten hexachloride. NMR and infrared analyses of the respective polymers indicate structures which are consistent with a ring‐cleavage mode of propagation. No evidence for double‐bond shifts or transannular reactions during the polymerizations of 1,5‐cyclooctadiene, 1,5,9‐cyclododecatriene, 3‐methylcyclooctene, and 3‐phenylcyclooctene was found. The polymerizability of substituted, unsaturated, mediumsized alicyclic monomers suggests a convenient method for synthesis of certain perfectly alternating terpolymers. Since polymerizations occurred rapidly with little evolution of heat, it was concluded that entropy is a substantial contributor to the free energy of the ring‐opening polymerization of medium‐sized, unsaturated alicyclic monomers.
Aminobutadienes. V. Polymers of 1‐phthalimido‐1,3‐butadiene and 1‐succinimido‐1,3‐butadiene
Authors: Terada Akira , Murata Kenichi 
Published: April 2003

AbstractThe radical polymerizations of 1‐phthalimido‐1,3‐butadiene (1‐PB) and 1‐succinimido‐1,3‐butadiene (1‐SB) were carried out in bulk and in solution. The polymers obtained had reduced viscosities in the ranges of 1.0–4.0 (1‐PB) and 0.2–0.6 (1‐SB). Both polymers had a similar softening point of 190–200°C. The radical polymerization of 1‐phthalimido‐1,3‐butadiene clearly showed a tendency to give crosslinked polymer. Steric arguments about these polymer structures as a result of the infrared and ozonolysis data led to the conclusion that these polymers contained approximately 20% of the 3,4 form but no 1,2 configuration, and, therefore, that the 1,4 addition was preferred.
Polymerization of β‐cyanopropionaldehyde. II. Crystalline poly(cyanoethyl)oxymethylene
Authors: Sumitomo Hiroshi , Kobayashi Kazukiyo 
Published: April 2003

AbstractAdditional investigation was made on the polymerization of β‐cyanopropionaldehyde at −78°C. with triethylaluminum and triethylaluminum—titanium tetrachloride complexes as initiators. The complexes give a higher polymer yield than triethylaluminum alone. The yield—Ti/Al plot also has a maximum at a Ti/Al mole ratio of about 0.2 at constant Al(C2H5)3 concentration. The rate of polymerization seems to be increased in the following order: toluene < methylene chloride < tetrahydrofuran. This order is reversed with regard to the content of DMF‐insoluble fraction mentioned below. The polymer obtained consists of two fractions: one is soluble in dimethylformamide (DMF) and the other is not. The former consists of an amorphous polymer and the latter of crystalline polymer. It was found that the infrared absorption bands at 790, 1258, and 1375 cm.‐1 were characteristic of crystalline polymer and were assigned to crystalline bands. Those at 1270 and 1345 cm.‐1 are characteristic of amorphous bands. The crystalline bands and COC bands show very intense infrared dichroism, whereas the nitrile band does not. The crystal data obtained from the analysis of the x‐ray diffraction pattern, including the fiber repeat distance of 4.95 A. and other unit cell dimensions in a triclinic system, were compared with those reported for various aldehyde polymers. The unit cell dimension a′ or the maximum interplanar distance is somewhat smaller, suggesting that the molecules are more tightly packed than poly(n‐butyraldehyde), in which the side chain has the same carbon number as that of poly‐(cyanoethyl)oxymethylene. Internal rotation angles and a radius of helix were calculated for an isotactic fourfold helical model of the polymer. Some other characterizations of the polymer were also made.
Effect of impurities and the initiation and transfer rate constants on the statistical character of anionic polymers
Authors: Nanda V. S. , Jain R. K. 
Published: April 2003

AbstractThe simultaneous effect of impurities, hite rate of initiation, and chain transfer through the monomer on the size distribution in anionic polymers is investigated. It is assumed that monomer is added to the system containing monofunctional initiators in small doses 80 that there is no accumulation of the monomer or the impurities at any stage of the reaction. Firstly, by using the continuum approach, expressions for the size distribution and the averages are derived for the case when initiation is infinitely fast and chain transfer is absent. These results are compared with those obtained by Oroho and Wenger by a more rigorous analysis, and the adequacy of the simpler results is established. The complexities arising from the finite rate of initiation and chain transfer are considered subsequently. Finally, we describe a procedure for the determination of the initiation and transfer rate constants in terms of propagation rate constant and the fraction of impurities in the monomer supply.
Kinetics of emulsion polymerization
Authors: Ugelstad J. , Mörk P. C. , Aasen J. O. 
Published: April 2003

AbstractThe quantitative theory of the free‐radical mechanism in emulsion polymerization is reexamined. A mechanism involving desorption and reabsorption of radicals is discussed. The average number of radicals per particle has been calculated as a function of three parameters. A simplified, approximate solution for the average number of radicals per particle is given for cases where this number is low.