bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid‐state polymerization of acrylamide and some acrylates initiated by ultraviolet radiation
Authors: Baysal B. M. , Erten H. N. , Ramelow Ü. S. 
Published: April 2003

AbstractThe solid‐state polymerization of acrylamide, potassium acrylate, and calcium acrylate by ultraviolet radiation have been investigated. For these polycrystalline monomers both in‐source and post‐irradiation reactions were studied by using various sources of different intensities at constant temperatures. It is concluded that the polymerization reactions take place primarily on the surfaces of crystals. The high molecular weight material obtained at low conversions show a rapid decrease in intrinsic viscosities, probably due to degradation. Both the rate and degree of polymerization were decreased by the presence of oxygen. The various behaviors observed for these three monomers under ultraviolet radiation were regarded as another indication of the importance of crystal structures upon the solid‐state polymerization reactions.
Polymerization by oxidative coupling. II. Co‐redistribution of poly(2,6‐diphenyl‐1,4‐phenylene ether) with phenols
Authors: White Dwain M. 
Published: April 2003

AbstractPoly(2,6‐diphenyl‐1,4‐phenylene ether) reacts with phenols in the presence of an initiator to form a mixture of low molecular weight hydroxyarylene ethers. Although the reaction is similar to the equilibration of poly(2,6‐dimethyl‐1,4‐phenylene ether) with phenols, higher reaction temperatures and larger initiator concentrations are required. Compounds as 3,3′,5,5′‐tetraphenyl‐4,4′‐diphenoquinone, tert‐butyl perbenzoate, and benzoyl peroxide are active initiators. The structure of the polymer affects the extent to which the polymer equilibrates.
Dependence of reactivity of propagation centers of oxide catalysts for ethylene polymerization on catalyst composition and activation conditions
Authors: Ermakov Yu. I. , Zakharov V. A. , Kushnareva E. G. 
Published: April 2003

AbstractThe propagation rate constant Kp was used as a measure of reactivity of propagation centers in ethylene polymerization with oxide catalysts. This constant was determined by a radiotracer quenching technique for oxide catalysts of different compositions and activation conditions. For catalysts based on various transition metal oxides, an increase of Kp was observed in the series W < Mo < Cr and V < Cr. In the case of chromium oxide catalyst it was shown that Kp value does not depend on the content of the transition metal in a catalyst. A change of propagation center reactivity was found when oxides of different composition (SiO2, Al2O3, ZrO2, TiO2) were used as supports. An increase of the vacuum activation temperature of a catalyst results in increasing Kp. Pretreatment of catalyst with different reducing agents (SO2, CO2, NH3, HCN) results in the change of Kp value in comparison in comparison with the catalyst activated by the vacuum treatment only. The data obtained on the variation of the reactivity of the propagation centers permit one to draw a conclusion about the composition of surface compounds as acitve centers of the oxide polymerization catalysts.
Reactivity of ethylene in the radically initiated copolymerization of ethylene with vinylacetate
Authors: Rätzsch M. , Schneider W. , Musche D. 
Published: April 2003

AbstractThe study of the literature shows that in the copolymerization of ethylene and vinylacetate there is an evident dependence on the relative reactivity of ethylene. For this change of the r‐value of ethylene there are two explanations: real change of reactivity of the ethylene, or effects of heterogeneity. The experiments were carried out under pressures from 100 to 300 ats and at temperatures from 60 to 200°C, as well as under 1200–2400 ats and at 160–240°C. We find that the change of the r‐value of the ethylene is caused by heterogeneity effects and the r‐values obtained must be considered as apparent r‐values.
Structure of chlorinated poly(vinyl chloride). I. Determination of the mechanism of chlorination from infrared and NMR spectra
Authors: Kolínský M. , Doskočilová D. , Scheider B. , Štokr J. , Drahorádová E. , Kuška V. 
Published: April 2003

AbstractInfrared and NMR spectra of chlorinated poly(vinyl chloride) (CPVC) and of chlorinated α‐deuterated poly(vinyl chloride) (α‐d‐CPVC) have been measured. It was found that the CDCl unit of α‐d‐PVC does not undergo chlorination. By assuming an analogous mechanism of chlorination in normal PVC, the populations of all the three possible types of two‐carbon sequences (CH2CHCl, CHClCHCl, CHCl CCl2) in CPVC could be determined. The mechanism of chlorination of PVC is discussed from the viewpoint of the previous findings on the conformational structure of this polymer. Differences in structure between suspension‐ and solution‐chlorinated PVC have been established.
Graft copolymerization of methyl methacrylate onto lignosulfonate by H2O2–Fe(II) redox system. I. Preparation and characterization of the graft copolymer
Authors: Nam Chongwon , Koshijima Tetsuo , Muraki Einosuke , Maku Takamaro 
Published: April 2003

AbstractGraft copolymerization of methyl methacrylate onto lignosulfonate in aqueous medium was investigated. It was found that the H2O2–Fe(II) redox system is very effective for the grafting (Ea = 4.4 kcal/mole). The H2O2/Fe2+ ratio was the most important factor in the graft copolymerization and characteristics of the resultant graft copolymers. In most cases, polymerization for 100 min at 30°C was enough to obtain 80% conversion and 50–60% grafting efficiency. The resultant polymer mixture was subjected to extraction alternately with acetone and water, and the graft copolymer was isolated free from homopolymer and unreacted lignosulfonate. With increasing H2O2/Fe2+ ratio, the grafting ratio showed a maximum at 4, whereas the yield of graft copolymer and number of poly(methyl methacrylate) branches for every building unit of lignosulfonate increased up to a ratio of 4, both values, however, remaining constant above 4. The graft copolymer obtained for the case H2O2/Fe2+ = 4 consisted of one part of lignosulfonate and five parts of poly(methyl methacrylate). The number of branches in the graft copolymer was 6 × 10−3/OCH3 or one every 167 guaiacyl nuclei.
Thermal degradation of poly(alkyl acrylates). III. A secondary ester: Isopropyl acrylate
Authors: Grassie N. , Speakman J. G. 
Published: April 2003

AbstractA quantitative analysis of the products of the thermal degradation of poly(isopropyl acrylate) has been made principally by the application of GLC and mass and infrared spectrometry. The major products are carbon dioxide and propylene. The carbon dioxide/propylene ratio is very low in the initial stages but converges to approximately 0.6 late in the reaction. There is some tendency to autocatalysis in the production of propylene. Carbon monoxide and isopropanol are very minor products, and there is no chain fragment fraction as in the degradation products of the poly(primary acrylates). Changes in the infrared spectrum of the polymer during degradation are in accordance with the formation of these products and the reaction characteristics are accounted for mechanistically.
Synthetic thermally reversible gel systems. VII
Authors: Haas Howard C. , Macdonald Ruby L. , Schuler Alan N. 
Published: April 2003

AbstractPolymethacrylylglycinamides (PMG), like polyacrylylglycinamides (PAG), form thermally reversible aqueous gels, but higher molecular weights and/or concentrations are required and the melting points of the gels are lower. The heats of crosslinking for aqueous PMG gels fall in the range of −5 to −10 kcal/mole of crosslinks, the same as for aqueous PAG gels, implying that the crosslinks are chemically similar. PMG and PAG are incompatible with each other but both are individually compatible with some types of gelatin. The solubilities of PMG and PAG are similar. Various reagents, however, affect PMG and PAG gels in quite different manners. Aqueous PMG solutions, just outside conditions required for gelation, are rheopectic. Intrinsic viscosities [η] of PMG in 2M NaCNS are about 2.5 times those in water. The Huggins' k′ value for PMG in 2M NaCNS has a value of 0.39–0.40, and both it and [η] are essentially temperature‐independent over the range 25–45°C. In water at 25°C for PMG, k′ has an average value of about 1.4. With increasing temperature, for H2O, there is a considerable increase in [η] which is accompanied by a decrease in the value of k′. Osmotic molecular weight measurements on unfractionated PMG in H2O at 40°C yield π/c versus c plots having essentially zero slope, implying a value of close to zero for the second virial coefficient, a value of about 0.5 for the polymer–solvent interaction parameter, and a condition close to a θ condition. An approximate viscosity–Mn relationship for polydisperse PMG is [η]2M NaCNS, 25deg;C = 1.7 × 10−8 Mn1.5. The low value of K and high value of the exponent do not result from large differences in polydispersity but rather from a stiff, rodlike configuration in solution. This steric hindrance to rotation also manifests itself in the extreme brittleness of PMG films and in a ΔHp for homopolymerization of only −6 kcal/‐mole. The infrared spectra of MG monomer and PMG are recorded as well as the density and refractive index for PMG. PMG has a glass transition at 226°C by DTA and by TGA, thermal decomposition sets in at about 300°C. From copolymerization with acrylic acid, values of 1.66 and +0.06, respectively, were obtained for the resonance factor Q and the electrical factor e for MG monomer.
Production of organometallic polymers by the interfacial technique. XX. Synthesis of polyoxystannyloxyalkylenes
Authors: Carraher Charles E. , Scherubel Gary A. 
Published: April 2003

AbstractPolyoxystannyloxyalkylenes of low to intermediate molecular weight were synthesized in low to high yield by a modified nonaqueous interfacial technique.
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At least some of the products possess SnCl, SnOH, and ROH endgroups. The aqueous stability of the products is in the order neutral ≫ basic > acidic.
Studies in some new initiator systems for vinyl polymerization. IV. Amino acids as the reducing component
Authors: Pramanick Dinabandhu , Palit Santi R. 
Published: April 2003

AbstractAmino acids have been found to form good redox initiator systems with halogens (Cl2 and Br2), KBrO3, KMnO4, and Fe(NH4)(SO4)2. The three systems, viz., glycine–Cl2, taurine–Cl2, and sulfamic acid–Cl2 incorporate amine, carboxy (or sulfoxy), chlorine, and hydroxy endgroups in the resulting polymers, the monomer investigated being mainly methyl methacrylate. On the basis of endgroup results it is suggested that initiation through amino acid radical, chlorine radical and also through some hydroxyl radicals takes place. The probable termination mechanism is discussed.
Synthesis and polymerization of some optically active 2‐ and 1,2‐substituted butadienes
Authors: Janović Z. , Fleš D. 
Published: April 2003

AbstractDehydration of (S)‐3,5‐dimethyl‐1‐hepten‐3‐ol gave: (3E)‐ (I) and (3Z)‐(5S)‐3,5‐dimethyl‐1,3‐heptadienes (II) and 2‐[(S)‐ 2‐methylbutyl]‐1,3‐butadiene (III). 2‐[(S)‐1‐Methylpropyl]‐1,3‐butadiene (IV) was also prepared similarly by dehydration of (S)‐3,4‐dimethyl‐1‐hexene‐3‐ol. Monomers I–IV we polymerized in the presence of the TiCl4–Al(i‐C4H9)3 catalyst system and in emulsion with K2S2O8 as initiator. Monomer IV was also polymerized in the presence of butyllithium. Specific rotations of polymers are of the same order of magnitude as that of monomers, with exception of polymers prepared by stereospecific polymerization of (S)‐I and (S)‐II. The acetone‐soluble fraction of these polymers has a molar rotation similar to that of monomer, while the acetone‐insoluble part has a lower rotation ([M]D of monomer +53.2°; [M]D of polymer, +5.9°).
Optical properties of inherently dissymmetric polyamides
Authors: Overberger C. G. , Ohnishi A. , Gomes A. S. 
Published: April 2003

AbstractA study of the optical rotatory dispersion (ORD), circular dichroism (CD), and ultraviolet spectra (UV) of polyamides derived from optically active biphenyl acid chlorides, and aromatic, and aliphatic diamines, was made. The optically active monomers were (–)‐(S)‐2,2′‐dinitro‐6,6′‐dimethylbiphenyl‐4,4′‐dicarbonyl chloride and (–)‐(S)‐2,2′‐dichloro‐6,6′‐dimethylbiphenyl‐4,4′‐dicarbonyl chloride. The diamines were o‐, m‐, and p‐phenylenediamine, piperazine, trans‐2,5‐dimethylpiperazine, and 1,2‐pyrazolidine. The ORD spectra of the o‐phenylenediaminepolyamide taken in different solvents indicated the existence of some ordered structure in the least polar solvent. All other polyamides existed in a random coil conformation in the solvents employed.
Polyesters from 12‐hydroxymethyltetrahydroabietic acid and 12‐hydroxymethyltetrahydroabietanol
Authors: Osman Maged A. , Marvel C. S. 
Published: April 2003

AbstractThe polyester of 12‐hydroxymethyltetrahydroabietic acid was prepared by the selfcondensation of the hydroxy acid (I) and from its methyl ester (II). The condensation reaction was studied and different catalysts investigated. The inherent viscosity of the polymers were measured and their DTA diagrams taken. A polyurethane as well as different polyesters of the diol (III) with methylene di‐p‐phenyl diisocyanate, terephthalic, adipic, suberic, and sebacic acids were synthesized. Mixed polyesters and polyamide ester were also prepared. The properties of the above described polymers were investigated and their behavior on DTA reported.
Nuclear magnetic resonance studies of isoprenyllithium derived from 1,1‐diphenyl‐n‐butyllithium‐3,4‐d5, and isoprene
Authors: Yuki Heimei , Okamoto Yoshio 
Published: April 2003

AbstractThe equimolar reactions of 1,1‐diphenyl‐n‐butyllithium‐3,4‐d5 (RLi) with isoprene (I) and isoprene‐1,4‐d4 (Id) were carried out in benzene‐d6 quantitatively to give isoprenyllithiums, RILi and RIdLi, respectively. From the NMR spectrum of the RILi it was proposed that the isoprene unit had cis‐1,4, cis‐4,1 and some unknown structures in benzene‐d6. When RILi was prepared in the presence of about one equivalent of THF to RILi, the anion was considered to include an isoprene unit in cis‐1,4, trans‐1,4, cis‐4,1, and probably 3,4 structures. The same anion was obtained even if an equimolar THF was added afterward to the RILi prepared in benzene‐d6 The RLi was reproduced by the reverse reaction from RILi, when a large excess of THF was added or the temperature of the solution was elevated. The results obtained were correlated with those of anionic polymerizations of isoprene by lithium initiators.
Photocondensation polymers: Polybenzopinacols. II. Photolytic coupling of aromatic diketones
Authors: McCombs D. A. , Menon C. S. , Higgins Jerry 
Published: April 2003

AbstractPhotolytic condensations of p,p′‐dibenzoyldiphenyl sulfide, p,p′‐dibenzoyldiphenyl ether, p,p′‐dibenzoyldiphenylmethane, and p,p′‐dibenzoyldiphenylethane with a 100‐W long‐wavelength ultraviolet lamp gave polypinacols having inherent viscosities ranging from 0.12 to 0.45. Treatment of the same monomers under similar conditions with a 450‐W ultraviolet lamp produced polypinacols having inherent viscosities ranging from 0.04 to 0.37.
Poly(ethylene sulfide). II. Thermal degradation and stabilization
Authors: Catsiff E. H. , Gillis M. N. , Gobran R. H. 
Published: April 2003

AbstractHigh molecular weight poly(ethylene sulfide) undergoes severe thermal degradation at the high temperatures (220–260°C) required for processing in injection‐molding equipment. Thermal degradation of the polymer is accompanied by gas evolution and a decrease in melt viscosity. Stabilization of poly(ethylene sulfide) can be effectively accomplished by addition of small concentrations of certain 1,2‐polyamines, preferably together with certain zinc salts as coadditives. Use of this stabilizer system inhibits thermal degradation to a remarkable extent, making it possible to mold the polymer at these high temperatures and obtain excellent physical and mechanical properties. Investigation of the thermal degradation process was carried out. The rate at which gases evolved from unstabilized poly(ethylene sulfide) resins of various molecular weights and preparative histories and from model compounds of the same organic backbone structure was measured at temperatures ranging from 220 to 260°C. Rate of gas evolution from the resins, irrespective of chain length or preparation, was found to be constant at 230°C. The evolved gases, analyzed by infrared spectroscopy and gas chromatography, contained ethylene. Nearly identical apparent activation energies were found for the gas evolution reaction from the resin and model compounds. The ΔE* values were in good agreement with ΔE* determined by other techniques, 58 ± 2 kcal/mole. This is about the energy requirement expected for the homolytic cleavage of a carbon–sulfur bond of the type present in a poly(ethylene sulfide) structure. The rate and analytical data indicate that the degradative mechanism at processing (molding) temperatures is primarily due to the organic structure of the polymer. A mechanism of thermal stabilization is proposed in which the polyamine and zinc salt, in presence of molten polymer at processing temperatures, form a two‐centered electron transfer complex, capable of reacting with both radicals of the homolytically cleaved bond, “healing” the scission, so to speak.
Organometal‐initiated polymerization of vinyl ketones. III. Polymerization of methyl isopropenyl ketone initiated by the triethylaluminum–methyl isopropenyl ketone complex
Authors: Lyons A. R. , Catterall E. 
Published: April 2003

AbstractThe kinetics and mechanism of the triethylaluminum–methyl isopropenyl ketone complex‐initiated polymerization of methyl isopropenyl ketone (3‐methyl‐3‐butene‐2‐one) in toluene have been studied over a range of temperature. Equimolar quantities of monomer and triethylaluminum were premixed to form the initiator species prior to the addition of the excess monomer for polymerization. Initial and overall reaction rates indicate a first‐order dependence on monomer and initiator concentrations. The overall activation energy for the polymerization is 52 ± 3 kJ/mole. Molecular weight distributions were bimodal, with peaks corresponding to the trimer and high molecular weight material. The kinetic data are consistent with a coordinate polymerization mechanism.
Soluble imide–quinoxaline copolymers
Authors: Augl Joseph M. , Duffy James V. 
Published: April 2003

AbstractEight new phenylated imide–quinoxaline ordered copolymers were prepared. The synthesis consisted of one‐step solution condensations of aromatic bis(o‐diamines) with N,N′‐bis(benzilyl)benzophenoneimide and N,N′‐bis(benzilyl)tetrahydrofuranimide respectively. The polymers were all of high molecular weight and were soluble in a number of different solvents. Thermal gravimetric analysis showed that the aromatic benzophenoneimide‐quinoxalines (decomposing between 490 and 530°C) were considerably more stable than the aliphatic tetrahydrofuranimide–quinoxalines (decomposing between 290 and 320°C). All polymers gave tough films which could be cast from solution.
Polymerization of acrylamide and acrylic acid photoinitiated by diazidotetramminecobalt (III) azide
Authors: Kothandaraman H. , Santappa M. 
Published: April 2003

AbstractThe kinetics of polymerization of acrylamide and acrylic acid in aqueous solution photoinitiated by the complex, diazidotetramminecobalt(III) was systematically studied at 35°C and pH = 3. Monochromatic radiation at γ = 365, 405, and 435 mμ was employed. The kinetics of polymerization were followed by measurements of the rates of monomer disappearance (bromometrically) and complex disappearance (spectrophotometrically) and the chainlengths of the polymers formed (viscometrically). The dependences of the rate of polymerization on variables like light intensity, light absorption by the complex, wavelength, monomer concentration, and hydrogen ion concentration were studied. The rates of polymerization of acrylamide and acrylic acid were found to be propertional to the square of the monomer concentration and to the first power of light absorption fraction ke and light intensity I. A kinetic scheme is proposed in the light of experimental results involving (1) a primary photochemical act of excitation of the complex, followed by the dark reaction of electron transfer within the complex producing the azide radical; (2) initiation of polymerization by the azide radical; (3) termination of the chain process by the complex molecule.
Electroinitiated polymerization of vinylic monomers in polar systems. I. Contribution of the electrolysis of methanol to free‐radical polymerization
Authors: Albeck M. , Königsbuch M. , Relis J. 
Published: April 2003

AbstractElectrolytic polymerization of acrylates and methacrylates in methanol solution containing lithium acetate as electrolyte was investigated under currents ranging from 10 to 100 mA. Polymer yield increases up to a limiting current value, beyond which it decreases. This abnormal behavior is discussed. A free‐radical mechanism is suggested.
Polymerizations with hydrido and alkyl transition metal complexes in aqueous media
Authors: Lentzner H. L. , De La Mare H. E. 
Published: April 2003

AbstractHydrido pentacyanocobaltate(III) and alkyl pentacyanocobaltate(III) have been studied as initiators for the polymerization of isoprene and butadiene in aqueous emulsion systems. The microstructure of the polymers is consistent with a free radical process. Other transition metal hydrides are relatively ineffective as polymerization initiators or act as inhibitors for the radical polymerization of the same dienes.
Graft and modified polymers from rubber network. I. Method of obtaining graft and modified polymers from sulfur vulcanizates with dehydrogenated Raney nickel and Raney cobalt
Authors: Nikolinski P. D. , Mirtscheva V. V. 
Published: April 2003

AbstractThe present paper reports on an investigation of eliminating sulfur from sulfur vulcanizates by using dehydrogenated Raney Ni (Raney Co). The dehydrogenated Raney metal eliminates the sulfur by forming free radicals which recombine with each other. The result is a heavily crosslinked product containing traces of sulfur. When applying dehydrogenated Raney metal in the presence of substances readily producing free radicals or monomers polymerizing by way of a free‐radical mechanism, one obtains a modified or a grafted high molecular product.
Electroinitiated copolymerization reactions with donor–acceptor complexes. III. Copolymerization of butadiene and acrylonitrile with ZnCl2 as catalyst
Authors: Funt B. Lionel , Rybicky Jaroslav 
Published: April 2003

AbstractThe passage of an electrolytic current initiated polymerization of acrylonitrile with butadiene to form an alternating copolymer. The rate of polymerization increased with increase in current, but the copolymer composition was invariant with current and with degree of conversion. A mechanism is proposed based on donor–acceptor complexes. The formation of these is facilitated by the addition of ZnCl2 which forms an initial complex with the acrylonitrile. Polymerization of the donor–acceptor complexes is initiated by electrochemically generated transient species whose rate of formation is dependent on the current.
Anionic graft polymerization of propylene sulfide on cellulose. I
Authors: Cohen Eliahu , Avny Yair , Zilkha Albert 
Published: April 2003

AbstractThe anionic graft polymerization of propylene sulfide on cellulose membrane was studied. Alkali cellulosates were used to initiate graft polymerization, and graft polymers of high polypropylene sulfide content were obtained in good yields. The graft polymerization was accompanied by a certain extent of homopolymerization. The effects of reaction solvent, monomer concentration, cellulosate degree of substitution, and type of the alkali metal cellulosate on the graft polymer composition, yield, and on the molecular weight of the grafted side chains were investigated.