bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electroinitiated cationic polymerization of styrene by direct electron transfer
Authors: Akbulut Ural , Fernandez Jack E. , Birke Ronald L. 
Published: April 2003

AbstractWe have studied by cyclic voltammetry the mechanisms of electron transfer and peak potentials of eleven alkenes, propylene oxide, propylene sulfide, and carbon disulfide. We have also studied the cationic polymerization of styrene in acetonitrile solution initiated by controlled potential electrolysis at the anodic peak potential of styrene. The electrolyte used was tetrabutylammonium fluoborate, which was not electroactive at the electrolysis potential, and the reference electrode was a Ag0/Ag+ electrode. The electrochemical studies show that direct electron transfer from styrene is the initiation steps. Plots of reacted monomer concentrations versus time are sigmoidal curves. The propagation rate constant was found from a kinetic relationship based on an autocatalytic reaction. The activation energy is 15.6 kcal/mole at 20°C. The current behavior and effect of stirring on polymerization rate suggest that the growth of polymer takes place partially on the electrode surface.
Photochemistry of nonconjugated bichromophoric systems: Photoreduction and photoreductive polyrecombination kinetics
Authors: De Schryver F. C. , Van Thien Tran , Smets G. 
Published: April 2003

AbstractThe kinetics of the photoreduction of benzophenone and the reductive photopolymerization of diaryl ketones are closely interrelated. The photoreductive polyrecombination presents the characteristics of a polycondensation, namely, an increase in molecular weight with reaction time. In the absence of side reactions, benzophenone and diketone Ia show identical behavior toward hydrogen abstraction, as is reflected in the di‐bis rate constants of hydrogen abstraction.
Preparation and polymerization of difluoramino‐substituted alkyl acrylates and methacrylates
Authors: Reed Samuel F. 
Published: April 2003

AbstractSeveral difluoramino‐substituted alkyl acrylic acid esters were conveniently prepared by the debromination of difluoramino‐substituted alkyl‐2,3‐dibromopropionates and 2,3‐dibromoisobutyrates. The polymerization character of difluoramino‐substituted alkyl acrylates and methacrylates was found to be similar to that displayed by other alkyl acrylic esters.
Initiator concentration dependence of the autoacceleration of polymerization rate
Authors: Ito Katsukiyo 
Published: April 2003

AbstractThe dependence of the polymerization rate on initiator concentration over a wide range of conversion is analyzed by an equation derived on the assumption that the primary radical termination is important and another equation derived on the assumption of the chain length dependence of the termination. The analytical result by the former equation, is nearly equivalent to the result by the later when transfer predominates. Fujita‐Doolittle theory is applicable to both results. In the apparent termination, small polymer radicals not exceeding the size of the segment play an important role.
Preparation of new heterocyclic monomers: Vinylisoxazoles, vinylpyrazoles, and vinylpyrazolones
Authors: Ponticello I. S. 
Published: April 2003

AbstractVinylisoxazoles, vinylpyrazoles, and vinylpyrazolones have been synthesized by cracking their cyclopentadiene adducts. The latter were derived from the blocked 1,3‐dicarbonyl compounds by treatment with hydroxylamine or hydrazine.
Temperature effects on γ‐initiated polymerization of styrene. III. Conversion in the range 150–200°C
Authors: Taherzadeh M. , Hodgins J. W. 
Published: April 2003

AbstractExperimental data are presented for the polymerization of commercial styrene in a γ‐radiation flux of 20–51 rad/sec in the temperature range of 150–200°C. At radiation intensities above 20 rad/second, conversion rate is independent of dose rate over the range. Above 165°C, radiation does not enhance the conversion rate but does produce more rapid elimination of residual monomer. Molecular weights of polymer product in this temperature range are too low to be of commercial interest. An optimal temperature range of 110–120°C is suggested for the process.
Cyclic acetal‐photosensitized polymerization. I. Photopolymerization of styrene in the presence of 1,3‐dioxolanes
Authors: Ouchi Tatsuro , Nakamura Sakuro , Hamada Masao , Oiwa Masayoshi 
Published: April 2003

AbstractStyrene(St) was polymerized in benzene solution in the presence of substituted 1,3‐dioxolane(DO) compounds by means of photoirradiation of the system at 40°C. The subtraction of the square of the polymerization rate in the absence of DO compounds (Rpab) from the square of the rate in the presence of DO compounds (Rppr) was found to follow the equation:

The effect of substituents in the 2‐position on the polymerization rate increased in the order of methyl < hydrogen < ethyl < n‐propyl < phenyl, as shown by the rate constant kd′ of decomposition of DO compounds.
Donor–acceptor complexes in copolymerization. XLIX. Cationic polymerization of donor monomers in presence of polar solvents and acrylic monomers. A revised mechanism for polymerization of comonomer complexes
Authors: Gaylord Norman G. , Deshpande Achyut B. , Dixit Sunit S. , Maiti Sukumar , Patnaik Birendra K. 
Published: April 2003

Abstractα‐Methylstyrene (MS) and isobutyl vinyl ether (VE) readily polymerize, styrene (S) polymerizes to a small extent, and isobutylene (IB), butadiene (BD), and isoprene (IP) fail to polymerize in the presence of catalytic amounts of AlCl3 when propionitrile, ethyl propionate, and methyl isobutyrate are used as reaction media. MS polymerizes readily and S polymerizes with difficulty in the presence of AlCl3 to yield homopolymers when acrylonitrile (AN) is present and copolymers with ethyl acrylate (EA) and methyl methacrylate (MMA). VE readily homopolymerizes, while IB, BD, and IP fail to polymerize in the presence of AlCl3 and the acrylic monomers. VE readily homopolymerizes, S and MS polymerize to a very small extent, and IB, BD, and IP do not polymerize in the presence of ethylaluminum sesquichloride (EASC) in polar solvents. VE readily homopolymerizes in the presence of EASC and the acrylic monomers. MS polymerizes to a small extent in the presence of EASC and the acrylic monomers to yield equimolar copolymers with EA and MMA and a mixture of cationic homopolymer and equimolar copolymer with AN. S yields equimolar copolymers in low yield in the presence of EASC and the acrylic monomers. IB, BD, and IP in the presence of EASC do not polymerize to any significant extent when EA is present, form AN‐rich copolymers and yield poly(methyl methacrylate) in the presence of MMA. A revised mechanism is presented for the formation of cationic, radical, random, and alternating copolymers as well as alternating copolymer graft copolymers in the copolymerization of donor and acceptor monomers.
Effect of molecular relaxations on the fracture behavior of poly(vinyl chloride)
Authors: Johnson F. A. , Radon J. C. 
Published: April 2003

AbstractThe fracture toughness of PVC has been measured by using three‐point bend specimens tested over a wide range of strain rate and temperature. A method has been described of deriving fracture load indirectly by measurement of stiffness from a preliminary “low blow” test in instrumented impact testing. Some limitations of the method, when used with semi‐ductile material of low stiffness, have been discussed. Fracture toughness results have also been evaluated by an alternative energy method, which is however more suitably applied to the lower speed impact test. The curves of K1c versus temperature for PVC contain a weak maximum at a temperature below Tg, the location of which varies with testing speed. The position of the maximum in the time–temperature field has been compared with the locus of the β damping peak derived from mechanical (flexural vibrations, torsion pendulum) and dielectric loss measurements, with reasonable agreement. Static toughness was higher than dynamic, and this correlated with fracture surface appearance, thereby indicating a real difference in toughness probably associated with crack tip craze development.
Influence of H2O on alternating copolymerization with the EtnAlCl3‐n‐VOCl3 catalyst system
Authors: Akimoto Akira , Ohtsuru Masaaki 
Published: April 2003

AbstractThe effect of the catalytic amount of H2O was investigated with the EtnAlCl3‐n‐VOCl3 catalyst system on the alternating copolymerization of acrylic monomers with diolefins and styrene. The presence of the catalytic amount of H2O produced an improvement in the yield and in the molecular weight as well as the structure of copolymer with the EtnAlCl3‐n‐VOCl3 catalyst system. The efficiency of the aluminum components in the EtnAlCl3‐n‐VOCl3 system appears with AlEt3 and especially with Et1.5AlCl1.5. The catalytic activity was found to depend upon the H2O EtnAlCl3‐n molar ratio and was also affected by the order of mixing of the catalyst components and the monomers. Effective catalyst could be prepared when the catalyst components (except VOCl3) were premixed without presence of monomers. The possible catalytic behavior of H2O was discussed.
Effect of diffusion on rates and molecular weights in graft polymerization
Authors: Odian George , Henry Richard , Koenig Raymond , Mangaraj D. , Trung Le Doan , Chao Bou , Derman Arif 
Published: April 2003

AbstractA theoretical analysis has been made of the graft polymerization process in terms of the quantitative interrelationship between the initiation rate Ri, the kp/kt1/ ratio of the monomer, the equilibrium solubility M of the monomer in the polymer, the polymer film thickness L, and the diffusivity D of the monomer in the polymer. It is shown how the values of these parameters in any grafting system interact to lead to diffusion‐controlled graft polymerization. Whether graft polymerization is diffusion‐free or diffusion‐controlled depends on the values of Kp, d, kp/kp1/2, and L as gathered in the parameter A = [(Kp/kt1/2)Ri, D,/1/2] L/2. When the values of the various terms are such that A is less than 0.1 (i.e., D is large while Ri, kp, and L are small), the reaction is diffusion‐free. When A is greater than 3 (i.e., D is small while Ri, kp, and L are large), the reaction is diffusion‐controlled. The derived equations showing the relationship between kinetic and diffusional parameters are theoretically applicable to all grafting systems, i.e., for all monomer‐polymer combinations under all conditions of reaction temperature, radiation intensity and polymer film thickness. The theoretical analysis has been verified for the rate and degree of polymerization for the radiation‐induced graft polymerization of styrene to polyethylene.
Effect of triphenyl phosphite on the radical polymerization of styrene and methyl methacrylate
Authors: Taninaka Takumi , Ogawa Takeshi , Minoura Yuji 
Published: April 2003

AbstractThe effects of triphenyl phosphite (TPP) on the radical polymerization of styrene (St) and methyl methacrylate (MMA) initiated with α,α,‐azobisisobutyronitrile (AIBN) was investigated at 50°C. The rate of polymerization of St and MMA at a constant concentration of TPP was found to be proportional to the monomer concentration and the square root of the initiator concentration. The rate of polymerization and the degree of polymerization of both St and MMA increased with increasing TPP concentration. The accelerating effect was shown to be due to the decrease of the termination rate constant kt with an increase in the viscosity of the polymerization systems. The chain transfer constant Ctr of TPP in St and MMA systems was determined from the degree of polymerization system. The Ctr of TPP was almost zero in the St system and 6.5 × 10−5 in the MMA system.
Polymers from 4,4′‐thiodiphenol
Authors: Samyn C. , Marvel C. S. 
Published: April 2003

AbstractPolyesters were made with aromatic diacid chlorides and 4,4,‐thiodiphenol. Isophthaloyl chloride and/or terephthaloyl chloride were used as acid chlorides alone or together with 5‐cyanoisophthaloyl chloride or [2.2]p‐cyclophane‐3,9‐dicarboxylic acid chloride. The latter components were incorporated in order to make the polymers useful for crosslinking. A polyether could be obtained by polycondensation of 2,4‐dichloro‐benzonitrile and 4,4′‐thiodiphenol. The polycondensations were run in nitrobenzene as solvent.
Polymerization of methacrylates. I. Polymerization reactivity of picryl methacrylate
Authors: Kadoma Yoshinori , Toida Takashi , Takeda Kenji , Uno Keikichi , Iwakura Yoshio 
Published: April 2003

AbstractThe polymerization of picryl (PMA), 2,4‐dinitrophenyl (2,4‐DNMA),2,6‐dinitrophenyl (2,6‐DNMA), 2‐methyl‐4,6‐dinitrophenyl (MDNMA), and 2,6‐dimethylphenyl methacrylates (DMMA) was carried out in benzene at 60°C. PMA, 2,6‐DNMA, and MDNMA did not undergo radical homopolymerization, while 2,4‐DNMA and DMMA did. The results suggest that the growing radical readily attacks the oxygen atom of the nitro group at the 2 position of the terminal phenyl group due to the steric effect of the substituent at the 6 position, resulting in chain termination. PMA formed a charge‐transfer complex with 2‐naphthyl methacrylate (NMA). The stoichiometric composition of this complex was shown to be 1:1 molar complex. PMA was readily copolymerized with NMA. The amount of solvent affected the composition of the copolymer obtained at a given same mole fraction in feed. The results suggest that charge‐transfer interaction between the ester groups affects the copolymerization mechanism.
Singlet oxygen and polymer photooxidations. I. Sensitizers, quenchers, and reactants
Authors: Zweig A. , Henderson W. A. 
Published: April 2003

AbstractA study designed to ascertain the role of singlet molecular oxygen in the photodegradation of plastics established that most classes of dye chromophores are sensitizers in polymer films, absorbing light and transferring the absorbed energy to ambient triplet ground state molecular oxygen, generating metastable reactive singlet molecular oxygen. Unsaturated polymers containing polybutadiene, polyisoprene, etc. are highly reactive to singlet oxygen produced through photosensitization, generating hydroxylic and carbonyl derivatives and losing their rubbery properties as consequences of such reactions. Many types of transition metal chelates are singlet oxygen quenchers. The relationships of the structures and spectroscopic properties of these chelates to their efficiency in quenching singlet oxygen are examined and discussed.
Studies on reactions of the N‐phosphonium salts of pyridines. XIII. Direct polycondensation reaction of carbon dioxide or disulfide with diamines under mild conditions
Authors: Yamazaki Noboru , Iguchi Tadao , Higashi Fukuji 
Published: April 2003

AbstractPolyureas of high molecular weight were obtained by the direct polycondensation reaction of carbon dioxide with diamines at 40°C for several hours under a pressure of carbon dioxide (below 30 atm) by use of diphenyl phosphite in pyridine. Optimal temperature and pressure were 40°C and 20 atm of carbon dioxide. The polycondensation reaction was also affected by solvents and type and amounts of tertiary amines. Pyridine was most effective as tertiary amine and solvent as well. Of the phosphorous compounds used, triaryl phosphites and diphenyl phosphite were most effective, but trialkyl phosphites failed to give polymer. The reaction was assumed to proceed via a carbamyl N‐phosphonium salt of pyridine formed by dephenoxylation of phosphites. Similarly, polythioureas were prepared by heating a mixture of carbon disulfide, diamines, and diphenyl phosphite in pyridine at 40°C for 6 hr under nitrogen.
Peculiarities in the copolymerization of trioxane and epichlorohydrin under the influence of EtB⊖F3 A⊕lEt2
Authors: Mateva R. , Pavlova M. , Kabaivanov V. 
Published: April 2003

AbstractThis study deals with the copolymerization of trioxane (TO) and 1‐chloro‐2, 3‐epoxypropane (epichlorohydrin, ECH) catalyzed by EtB⊖F3 A⊕lEt2 in toluene. The rate of exhaustion of monomers during copolymerization was measured by gas chromatography. It was established that no homopolymers were formed. The copolymers obtained show a high alkali resistance, indicating a statistical distribution of the ECH in the polymer chain. During the first stages of the copolymerization the ECH is exhausted almost instantaneously, whereas TO is gradually exhausted, finally reaching a certain equilibrium depending both on the quantity of the initial ECH and on the temperature at which the process was carried out. Copolymerization is inhibited at increased ECH levels, and only homopolymerization occurs at a certain critical concentration of ECH.
Donor‐acceptor complexes in copolymerization. L. Preparation and microstructure of chlorine‐containing alternating conjugated diene–acceptor monomer copolymers
Authors: Gaylord Norman G. , Patnaik Birendra K. 
Published: April 2003

AbstractNeighboring monomer units cause significant shifts in the infrared absorption peaks attributed to cis‐ and trans‐1,4 units in conjugated diene‐acceptor monomer copolymers. Conjugated diene‐maleic anhydride alternating copolymers apparently have a predominantly cis‐1,4‐structure, while alternating diene‐SO2 copolymers have a predominantly trans‐1,4 structure. Alternating copolymers of butadiene, isoprene, and pentadiene‐1,3 with α‐chloroacrylonitrile and methyl α‐chloroacrylate, prepared in the presence of Et1.5AlCl1.5(EASC), have trans‐1,4 unsaturation. Alternating copolymers of chloroprene with acrylonitrile, methyl acrylate, methyl methacrylate, α‐chloroacrylonitrile, and methyl α‐chloroacrylate prepared in the presence of EASC‐VOCl3 have trans‐1,4 configuration. The reaction between chloroprene and acrylonitrile in the presence of AlCl3 yields the cyclic Diel‐Alder adduct in the dark and the alternating copolymer under ultraviolet irradiation. The equimolar, presumably alternating, copolymers of chloroprene with methyl acrylate and methyl methacrylate undergo cyclization at 205°C to a far lesser extent than theoretically calculated, to yield five and seven‐membered lactones. The polymerization of chloroprene in the presence of EASC and acetonitrile yields a radical homopolymer with trans‐1,4 unsaturation.
Structural irregularities in poly(vinyl alcohol)
Authors: Adelman Robert L. , Ferguson Raymond C. 
Published: April 2003

AbstractPoly(vinyl alcohols) derived from the product of polymerization of vinyl acetate in methanol have been characterized by various physical and chemical methods before and after NaIO4 cleavage. The 220‐MHz 1H‐NMR spectra confirm the reliability of NaIO4 titrimetry for estimating 1,2‐glycol content and help explain the tendency for viscometry to grossly underestimate the 1,2‐glycol content for low molecular weight polymers. The spectra and related chemical evidence indicate that the major endgroups are HOCH2CH2 and CH3CH(OH)CH(OH)CH2. ß‐Hydroxyethyl groups also occur as short chain branches, mainly attached to α carbon atoms in the normal head‐to‐tail polymer chain sequence. The concentrations of the branch and endgroups depend on polymerization conditions and help explain polymerization “solvent” effects on physical properties.
Alternating structures in copolymers as elucidated by microozonolysis
Authors: Hackathorn Marjorie J. , Brock M. J. 
Published: April 2003

AbstractThe technique of microozonolysis followed by gas chromatography has been used to determine the amount of 1,2‐structures occurring as 1,4–1,2–1,4 sequences in n‐butyl‐lithium‐initiated polybutadienes. The product obtained from the ozonolysis of these sequences, 3‐formly‐1,6‐hexanedial, was directly proportional to the 1,2 (vinyl) content of the polymers as measured by infrared or NMR spectroscopy. An unusual ozonolysis product, 4‐octene‐1,8‐dial, has been found in the ozonolysis products of high‐1,4 poly‐butadienes. Ozonolysis has also been used to determine alternating structures in propylene‐butadiene copolymers. The product obtained from ozonolysis of such structures is 3‐methyl‐1,6‐hexanedial. Ozonolysis of a polyisoprene containing equal amounts of 1,4 and 3,4 structures indicated it to have a nonalternating structure with long blocks of 1,4‐isoprene units. Gas chromatographic separation was accomplished by using sucrose acetate isobutyrate with Carbowax 20M as the liquid phase. Retention times were established by using model compounds where possible.
Singlet oxygen and polymer photooxidations. II. Photodegradation of an olefinically unsaturated polymer
Authors: Zweig A. , Henderson W. A. 
Published: April 2003

AbstractA method based on infrared spectral changes in thin films was devised and used to evaluate the relative effectiveness of various types of additives on photodegradative processes in an olefinically unsaturated polymer. Nickel chelates of the thiobisphenol‐amine complex type are shown to be quantitatively more effective in retarding the photodegradation of these polymers than other additives having greater singlet oxygen quenching efficiencies, ultraviolet absorption, or radical antioxidant properties. Photosensitization with a singlet oxygen sensitizer (fluoranthene) rapidly produces degradative effects in the polymer which are identical with those of its direct degradation by light. The sensitized effects are also retarded by the nickel chelates. Photosensitization by a hydrogen atom‐abstracting sensitizer (a benzophenone) proved considerably less effective. The effectiveness of the nickel complexes appears to be due to a combination of their ability to quench singlet oxygen and precusor excited states and their relative stability under photoexposure conditions.
Determination of crystallinity of olefin copolymers and polyolefin powders by inverse gas chromatography
Authors: Braun J.‐M. , Guillet J. E. 
Published: April 2003

AbstractStudies of olefin copolymers by inverse gas chromatography show that the method is suitable for determining the crystallinity of compositions where a linear extrapolation of density determinations is not applicable. Satisfactory estimates of crystallinity were obtained on ethylene copolymers with carbon monoxide and vinyl acetate and on an emulsifiable polyethylene wax. Studies were also made in which the columns were packed with physical mixtures of GC support and polyolefin powders, either obtained direct or ground from film samples. It was shown that good estimates of crystallinity could be obtained if suitable allowance is made for variance in peak retention time with flow rate, due to the relatively slow rate of diffusion of the probe molecule in polymer particles of large diameter (>100 μm). If smaller particles are used it is usually unnecessary to correct for flow rate effects. This extends the usefulness of the “molecular probe” technique to any polyolefin sample which can be ground to a fine particle size and eliminates the need for solution coating of the column packing.
Anionic polymerization of N‐ethyl‐2‐vinylcarbazole and N‐ethyl‐3‐vinylcarbazole
Authors: Limburg W. W. , Yanus J. F. , Williams D. J. , Goedde A. O. , Pearson J. M. 
Published: April 2003

AbstractThe polymerization of N‐ethyl‐2‐vinylcarbazole and N‐ethyl‐3‐vinylcarbazole by an anionic mechanism has been demonstrated. Polymerization reactions were monitored by ultraviolet/visible spectroscopy and λmax and ε values for the propagating carbanions determined. The 2‐vinyl monomer exhibits all the features of a standard “living” polymer; the carbanion is stable at ambient temperatures and high molecular weight, M̄n ≃ 106, narrow distribution polymers and block copolymers with styrene have been prepared. The carbanion from the 3‐vinyl monomer is much less stable and a clean polymerization can only be conducted at temperatures below ‐60°C. A comparison of the anionic polymerization characteristics of the N‐, 2‐, and 3‐vinyl carbazole monomer series is presented.