bluuebunny/crossref_metadata_2025 huggingface dataset:
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

The 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

The 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

Infrared 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

Graft 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

A 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

Polymethacrylylglycinamides (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

Polyoxystannyloxyalkylenes 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

Amino 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

Dehydration 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

A 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

The 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

The 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

Photolytic 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

High 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

The 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

Eight 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

The 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

Electrolytic 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

Hydrido 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

The 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

The 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

The 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.
Polymerization of 4‐vinylpyridinium salts. III. A clarification of the mechanism of spontaneous polymerization
Authors: Salamone J. C. , Snider B. , Fitch W. L.
Published: April 2003

The mechanism of the spontaneous polymerization of 4‐vinylpyiridine on quaternization or protonation has been investigated. Results indicate that initiation is caused by the nucleophilic attack of 4‐vinylpyridine on the double bond of 4‐vinylpyridinium ion. It was shown that halide ions do not contribute significantly to the initiation. In the case of acid salts of 4‐vinylpyridine a hydrogen‐transfer polymerization occurred to give an ionene polymer with pyridinium units in the main chain. The “matrix” polymerization of 4‐vinylpyridine on poly(phosphoric acid) or poly(acrylic acid) also resulted in ionene formation. Conditions under which stable 4‐vinylpyridinium salts can be obtained are discussed.
Effect of formaldehyde on the cationic polymerization of styrene
Authors: Fukuda Wakichi , Ogata Norio , Kakiuchi Hiroshi
Published: April 2003

Polymerization of styrene has been carried out in the presence of formaldehyde at 30°C in benzene solution by using boron trifluoride etherate as a catalyst. The rate of polymerization in the initial stage was accelerated with addition of formaldehyde, while the steady‐state rate of polymerization was retarded in the presence of formaldehyde. The acceleration for the rate of polymerization was found only in a short time from the beginning. The steady‐state rate of polymerization followed the equation:

where [C]0 and [F]0 are initial concentrations of catalyst and formaldehyde, [M] is the monomer concentration, and k1, k2, and k3 are constants. It has been assumed that the chain‐transfer reaction does not involve formaldehyde itself but rather the reaction products of formaldehyde, such as polystyrene having ethoxy or hydroxymethyl ends. The apparent chain‐transfer constant for the added formaldehyde has been determined to be 1.63.
Complex of copper(II) with phenoxo and hexamethylphosphoramide ligands and its decomposition
Authors: Tsuruya S. , Kawamura T. , Yonezawa T.
Published: April 2003

The 2,4,6‐trichlorophenoxo–hexamethylphosphoramide(HMPA)–copper(II) complex was isolated by the reaction of copper(II) chloride with 2,4,6‐trichlorophenol, sodium methoxide, and HMPA in methanol solvent under an atmosphere of nitrogen. This complex has the composition of Cu·HMPA·2(C6H2Cl3O). The molecular weight determination was consistent with the copper(II) complex of binuclear structure. The infrared, electronic, and ESR spectra and magnetic susceptibility of the copper(II) complex are discussed in relation to its structure. Decomposition of the copper(II) complex in refluxing benzene yielded poly(dichlorophenylene oxide), coupling product of the 2,4,6‐trichlorophenoxo ligand of the copper(II) complex. Electron spin resonance (ESR) measurements on the copper(II) complex in the solid state in a degassed sealed tube at 120 ± 5°C indicated that the phenoxy radical was generated during the period of decomposition and the intensity of the ESR spectra based on copper(II) ion decreased with the measurement time. From these ESR spectra, a possible initial step involving one electron transfer of the decomposition of the 2,4,6‐trichlorophenoxo–HNPA–copper(II) complex is discussed.
Vinyl polymerization initiated by chromic acid–reducing agent systems
Authors: Viswanathan S. , Santappa M.
Published: April 2003

A kinetic study of the thermal polymerization of acrylonitrile initiated by chromic acid–reducing agent (n‐butanol, ethylene glycol, cyclohexanone, and acetaldehyde) systems was made. Chromic acid alone did not initiate polymerization under deaerated or undeaerated conditions. On the basis of the experimental determination of the dependencies of various variables on the rate of polymerization Rp, the rate of chromium (VI) disappearance −RM, the degree of polymerization DP, etc., a reasonable kinetic scheme was arrived at. The mechanism with the reducing agents, n‐butanol, cyclohexanone, and ethylene glycol, was found to be similar but different from that with acetaldehyde. Evidence has been presented to prove the formation of radical intermediates formed by the oxidation of the reducing agent by Cr(IV). Rate parameters for oxidation of the reducing agent and polymerization of the monomer were evaluated.
Triad tacticity of polyacrylonitrile
Authors: Matsuzaki Kei , Okada Munehisa , Uryu Toshiyuki
Published: April 2003

The high‐resolution NMR spectra of polyacrylonitrile‐β,β‐d2 prepared by radical polymerization were determined, and the stereoregularity of the polymer was studied. The NMR spectra of methine protons of polyacrylonitrile‐β,β‐d2 in dimethyl sulfoxide‐d6 and a mixture of nitromethane‐d3 and ethylene carbonate showed three partially resolved multiplets. The deuterium‐decoupled spectra of the polymer were measured, and three well resolved peaks were observed in the two solvents and dimethylformamide‐d7. These three peaks were analyzed by comparison with the NMR spectra of model compounds and polyacrylonitrile‐α‐d, and they were assigned to isotactic, heterotactic, and syndiotactic triads with decreasing magnetic field. This order seems to be unchanged in other solvents. Triad stereoregularity of the polymer was determined according to the assignment. Polymerizations of acrylonitrile‐β,β‐d2 by radical initiators between −78°C and 60°C were explained by the Bernoulli trial propagation step. The polymers had an atactic structure, independent of polymerization temperature. This shows that in free‐radical polymerization of acrylonitrile, the chain end is not represented as having any particular stereochemistry. Other stereochemical control is necessary to produce tactic polymers. The triad tacticity of isotactic polyacrylonitrile was also determined.
Interfacial synthesis of polyphosphonate and polyphosphate esters. V. Poly(phosphonate esters) containing thymidine, 2‐deoxy‐d‐ribose, or xanthine
Authors: Millich F. , Carraher C. E.
Published: April 2003

Poly(phosphonate esters) were synthesized by base‐promoted interfacial polycondensation of phenylphosphonic dichloride with thymidine and with 2‐deoxy‐D‐ribose. The products give evidence of P‐Cl endgroups. The thymidine product is a high polymer with a weight‐average number of repeating units, DPw, greater than 250. The 2‐deoxy‐D‐ribose product is separable into soluble and insoluble (crosslinked) fractions having identical infrared spectra. Xanthine is also reactive in the process employed.
Copolymerization characteristics of S‐vinyl‐O‐tert‐butylthiocarbonate
Authors: Daly W. H. , Lee Chien‐Da S. , Overberger C. G.
Published: April 2003

Poly‐S‐vinyl‐O‐tert‐butylthiocarbonate is an excellent precursor to poly(vinyl mercaptan) because the tert‐butyloxycarbonyl blocking group can be removed by either acid hydrolysis or thermolysis under conditions which minimize the oxidation of the liberated mercaptan to disulfide. Dilatometric studies of the homopolymerization of S‐vinyl‐O‐tert‐butylthiocarbonate demonstrated that the polymerization rate was directly proportional to the concentration of free‐radical initiator; no thermal initiation was observed. The molecular weight of the homopolymers and copolymers ranged from 30,000 to 50,000 (GPC). Copolymerization of S‐vinyl‐O‐tert‐butylthiocarbonate (M2) with styrene, (r1 = 3.0, r2 = 0.2), methyl methacrylate (r1 = 1.40, r2 = 0.17) and vinyl acetate (r1 = 0.04, r2 = 11.0) indicated that a sulfur atom adjacent to the vinyl group increases the resonance stability (Q2 = 0.5) and the electron density (e2 = −1.4) of the double bond and the corresponding radical. Water‐soluble copolymers could be prépared by incorporating either N‐vinylpyrrolidone (r1 = 0.12, r2 = 3.94) or N‐isopropylacrylamide (r1 = 1.17, r2 = 0.3) with M2. The water solubility of the copolymers decreased markedly when the tert‐butyloxycarbonyl group was removed. Copolymers of M2 with N‐vinyl‐O‐tert‐butylcarbamate (r1 = 0.13, r2 = 5.10) were utilized to prepare crosslinked poly(vinyl amine–vinyl mercaptan); the crosslinking resulted from urea linkages formed during thermolysis of the copolymer.
Electroinitiated polymerization of vinylic monomers in polar systems. II. Polymerization of ethyl methacrylate in methanol solutions
Authors: Albeck Michael , Relis Joseph
Published: April 2003

Ethyl methacrylate is polymerized by electroinitiation in methanol–electrolyte mixtures in which the monomer is soluble whereas the polymer obtained is insoluble. A technique of changing the polarity of the electrodes is used. With this technique a polymer of high molecular weight can be obtained. The relationships between molecular weight and monomer concentration, current densities, and time of the reaction as well as the yield as a function of current density, time of the reaction and initial monomer concentration are given. A free‐radical mechanism is proposed for the reaction.
Polybenzopinacolones. Acid‐catalyzed rearrangement of aromatic polybenzopinacols
Authors: McCombs D. A. , Menon C. S. , Higgins Jerry
Published: April 2003

Polybenzopinacols resulting from the photocondensations of p,p′‐dibenzoyldiphenyl ether, p,p′‐dibenzoyldiphenylmethane, and p,p′‐dibenzoyl‐1,2‐diphenylethane were rearranged in sulfuric acid–dioxane solutions. The inherent viscosities of the polybenzopinacolones did not differ significantly from the inherent viscosities of the polybenzopinacols after rearrangement. A model compound study by NMR and infrared methods indicated that the polymer chain was probably the main migrating group for each of the polymer rearrangements.
Grafting on wool. I. Electron microscopic studies on the location of grafted polymer in wool structure
Authors: Arai Kozo , Negishi Michiharu
Published: April 2003

To determine the location of grafted poly(methyl methacrylate) in orthocortex structure of fine Australian Merino wool fibers, high‐resolution electron microscopy was used. Optimal staining conditions for the observation of the deposited polymer were also studied. It was supposed that the grafted polymer is located mainly between the microfibril and matrix and around the protofibrillar subunits, but not in the matrix. The average space occupied by a grafted chain was estimated to be about four times as large as the total residue volume per polymer. It is supposed that the remarkably large space available per polymer chain is related to the excessive swelling seen with respect to the polymer uptake.
Grafting on wool. II. Stress–strain behavior of grafted fiber in water
Authors: Arai Kozo , Negishi Michiharu , Suda Tsutomu , Doi Kazuko
Published: April 2003

The stress–strain behavior and hysteresis properties of various grafted wool fibers were studied. Three distinct regions on the stress–strain curve and hysteresis properties characteristic of the native wool fiber remain substantially intact, even though a large amount of a rigid polymer occurs. It was suggested that the microfibril and the matrix nature in the native wool fiber exist in the grafted wool structures. The electron microscopic results were also supported. These results can be explained on the basis of Menefee's model that the longitudinal mechanical behavior is more directly controlled by a high modulus matrix.
Determination of chlorine distribution in chlorosulfonated polyethylenes by high‐resolution NMR spectroscopy
Authors: Brame Edward G.
Published: April 2003

High‐resolution proton magnetic resonance (NMR) spectroscopy was used to determine the sequence distribution of chlorines in elastomeric chlorosulfonated polyethylenes. The determination is based on measuring the relative amounts of methylene groups that are α, β, and γ (or greater) from chlorine containing groups (CHCl groups) in chlorosulfonated polyethylenes. The results obtained from the NMR examination at 220 MHz were compared with the theoretical predictions based on the statistics of substitution polymers. The comparison showed that polyethylenes chlorosulfonated by a solution reaction with gaseous chlorine and sulfur dioxide show a random chlorine distribution.
Effect of pH on the reactivity ratios in the copolymerization of acrylic acid and acrylamide
Authors: Cabaness W. R. , Lin T. Yen‐Chin , Párkányi C.
Published: April 2003

The content of acrylic acid and acrylamide in their copolymers can be controlled by changing pH. The reactivity ratio of acrylic acid decreases with increasing pH, while the reactivity ratio of acrylamide increases with increasing pH. At low pH values, acrylamide is present in its protonated form which causes its reactivity to be low whereas at high pH values the reactivity of acrylic acid is decreased owing to its dissociation. When the monomer and radical approach each other, the acrylate anion becomes the least reactive species because of its symmetrical charge distribution, like charge repulsion and barium ion screening effect. HMO calculations were performed for models of all monomers and polymer radicals involved in copolymerizations. The experimental results concerning the reactivity of acrylic acid and acrylamide in copolymerization and the observed reactivity ratios were discussed on the basis of HMO calculations and resonance and Coulomb electrostatic effects. The observed reactivity ratios were correlated with the calculated differences in resonance energies computed for the models of transition states involved in copolymerizations.
Gel‐permeation chromatography. V. A study of “overloading effects”
Authors: Ouano A. C.
Published: April 2003

In the calculation of molecular weight averages from GPC chromatograms and in the correction for zone broadening effects, it is assumed that the retention volumes of the individual species are not affected by the presence of the other components in the sample (linear fractionation process). This assumption was tested by the computer comparisons of the chromatograms of mixtures of narrow molecular weight distribution polystyrene standards and the envelopes of the individual chromatograms of the components of the mixtures. Disagreements between experimental and computer synthesized chromatograms were interpreted as non‐linear fractionation effects. The investigation covered a range of molecular weights (1.8 × 106 to 2100), molecular weight distributions (binary and seven component mixtures), and sample loadings (2 to 70 mg). Accurate normalizations of raw GPC chromatograms and calculations of molecular weight averages were made possible through an automated GPC apparatus using a high‐speed computer for data acquisition and data reduction. It was found that some nonlinear fractionation effects (large disagreement between chromatograms of the mixture and the computed envelopes of the individual chromatograms of the components of the mixture) became more pronounced as sample loading was increased and as the molecular weight distribution of the sample narrows. The nonlinear effect was also found to be sensitive to the molecular weight of the sample.
Analysis of resoles by gel‐permeation chromatography
Authors: Wagner E. R. , Greff R. J.
Published: April 2003

Resoles, the complex, heat‐sensitive product mixture from the alkali‐catalyzed reactions of phenol with formaldehyde were investigated by gel‐permeation chromatography (GPC). The low molecular weight species of these resins which consisted of mono‐and dinuclear methylol phenols were resolved into multiple peaks. Model compounds were used to identify the peaks of the specific methylol phenols or methylene etherbridged diphenols. Differences in the refractive index of individual species restricted the quantitative analysis of low molecular weight components in the resole. The effects of sodium and barium hydroxides and hexamethylene‐tetramine as catalysts, reaction temperature, and time on the total composition of a resole are demonstrated with the gel‐permeation chromatographic spectrum and with the aid of NMR. Formation of a “secondary” resole by methylolation of the bisphenol of formaldehyde was also monitored by GPC.
Study of the reaction of polyester resins with magnesium oxide
Authors: Alvey Francis B.
Published: April 2003

The reaction of polyester resin and magnesium oxide, which is the basis of the thickening process of sheet‐molding compound technology, has been characterized in a systematic study. The effect of reactant equivalency ratios, temperature, and added water on viscosity development have been determined. Excess amounts of magnesium oxide are necessary for thickening. Water increases the initial rate of thickening but reduces the overall level attained. A new thickening mechanism is proposed on the basis of a model study with polyester resin and sodium hydroxide.
Polymerization of α‐methylstyrene by living polymer in tetrahydrofuran
Authors: Podolsky A. F. , Dashkin R. Ch. , Korotkov A. A.
Published: April 2003

Kinetics of polymerization of α‐methylstyrene by poly‐α‐methylstyrylsodium (a “living” polymer) has been studied in tetrahydrofuran at −78°C. Complex dependences were established: that of the conversion X on reduced time φ and that of the apparent rate constant for the polymer chain propagation on conversion X and on the concentration of living polymers and monomer. The experimental data obtained were explained by assuming a coordination mechanism of anionic polymerization including the following elementary reaction: (a) generation of active polymerization centers (K1) by interaction of the living polymer with the monomer; (b) propagation of the polymer chains (K2); (c) monomolecular (K31) and bimolecular (K32) reactions of isomerization of active centers resulting in the formation of high molecular weight living polymers capable of again becoming active centers of polymerization. Approximate derivation of kinetic equation was carried out and the constants of elementary reactions were determined (K1 = 0.15, K2 = 24, K32 = 14.1./mole‐min and K31 = 0.05 min−1). The coincidence of the expected dependencies X = F(τ; φ) Kp = F(X; n0−1/2); dx/dτ = F(n0) with the experimental ones was followed with the aid of computers. The expected change in the values of X and Kp depending on the contribution of each elementary reaction to the overall polymerization process was analyzed.
Helical concept of the fine structure of cellulose
Authors: Ahmed A. U. , Rapson W. H.
Published: April 2003

The helical concept of the fine structure of cellulose as proposed by Manley is discussed. The deuterium exchange experiments with cotton, cotton crystallites, and regenerated cellulose I, in which accessibility was determined by comparing the ratio of the infrared absorbance of the OD peak to the OH peak, revealed that the accessibility of cotton linters decreased on acid hydrolysis, whereas it increased on treatment with ethylamine followed by washing with water. This is in contrast to the finding of Manley, who had evaluated the accessibility by a gravimetric D2O exchange method and had come to the conclusion that acid hydrolysis did not change the accessibility of cellulose and hence cellulose did not contain crystalline and amorphous phases but was all crystalline. On the basis of Manley's protofibril and the accessibility data obtained in this investigation, a concept of the fine structure of cellulose is proposed, in which the role of Manley's protofibril is analogous to the role of individual molecule in the fringe micellar model. This concept explains the properties of cellulose that are otherwise explainable on the currently accepted fringe micellar theory. In addition, it explains the marked shrinkage in the length of cotton and rayon fibers when placed in 16% sodium hydroxide solution.
Free‐ionic polymerization of isobutyl vinyl ether by radiation
Authors: Hayashi Kanae , Hayashi Koichiro , Okamura Seizo
Published: April 2003

Radiation‐induced free‐ionic polymerization of isobutyl vinyl ether in bulk system has been studied by dilatometry and electrical conductivity measurement. Some refinements in kinetic treatment of estimate the propagation rate constant kp from the rate of polymerization and steady‐state conductivity were attempted. Polymerization of superdried monomer which gave a half‐power dose‐rate dependence of Rp was carried out at 0, 25, and 50°C. The kp value obtained at 25°C and an activation energy for propagation were estimated as 1.2 ± 0.4 × 105 I./mole‐sec and 9.6 ± 2.8 kcal/mole, respectively. In isobutyl vinyl ether, a propagation reaction in free‐ionic mechanism was found to be characterized with a high frequency factor and presumably higher activation energy, compared with ion‐pair mechanism. Discussions were also made as to several contrasting behaviors between the polymerization of alkyl vinyl ethers and other vinyl monomers as styrene both in free‐ion and ion‐pair mechanisms.
Stereoregularity of radically polymerized poly(alkyl acrylates) and poly(trimethylsilyl acrylates) and the preparation of syndiotactic poly(methyl acrylate)
Authors: Uryu Toshiyuki , Shiroki Hiroyuki , Okada Munehisa , Hosonuma Kunihiko , Matsuzaki Kei
Published: April 2003

Nuclear magnetic resonance (NMR) spectroscopy was used to determine the stereoregularity of radically polymerized poly(ethyl acrylates), poly(trimethylsilyl acrylates), and poly(isopropyl acrylate‐α,β‐d2). The ethyl acrylate polymers consisted of a random configuration having about 50% of isotactic diads, and their stereoregularities were independent of the polymerization temperature (40 to −78°C). Poly(trimethylsilyl acrylates) and poly(isopropyl acrylate‐α,β‐d2) prepared at low temperatures had a syndiotactic configuration. Syndiotactic poly(methyl acrylate) was derived from syndiotactic poly(trimethylsilyl acrylate). For poly(methyl acrylate), an approximate estimation of the stereoregularity by infrared spectroscopy was proposed.
Analysis of polymerization rates in radical polymerization with primary radical termination of methyl methacrylate initiated by 2,2′‐azobis(2,4‐dimethyl valeronitrile)
Authors: Ito Katsukiyo
Published: April 2003

Polymerization rates in radical polymerization of methyl methacrylate initiated by 2,2′‐azobis(2,4‐dimethyl valeronitrile) under various conditions were analyzed by using a previously derived simple equation. The results obtained are discussed on the basis of the relation of solvent viscosity and temperature. It is concluded that chain termination rate constant is inversely proportional to the solvent viscosity, but primary radical termination rate constant can not be related immediately to solvent viscosity.
Photo‐induced graft copolymerization of methyl methacrylate on cellulose
Authors: Ogiwara Yoshitaka , Kubota Hitoshi
Published: April 2003

Graft copolymerization initiated by ultraviolet light irradiation at 40°C in a hard glass vessel under nitrogen was examined. The graft copolymerization was observed to occur easily after some induction period without any use of photosensitizer, though it was found the per cent grafting and the grafting efficiency were markedly affected by the quantities of cellulose and monomer. In the system without cellulose, homopolymerization of methyl methacrylate hardly took place, but the use of cellulose caused the formation of homopolymer too, and a grafting efficiency in the range of 60–80% generally resulted. Ferric chloride or sodium anthraquinone‐2,7‐disulfonate (AQ) acted on the polymerization reaction as photosensitizers to reduce its induction period. Though ferric chloride acted to develop both the per cent grafting and the number of grafts, not the same effects were observed with AQ. Oxalic acid, which was employed with the object of eliminating very small amount of metals contained in cellulose, was found to act favorably in the formation of grafts, much like ferric chloride.
Coordination catalysts for the selective hydrogenation of polymeric unsaturation
Authors: Falk John Carl
Published: April 2003

The selective hydrogenation of poly‐1,4‐butadiene in the presence of poly‐1,4‐isoprene is described. Both of these polydienes are hydrogenated more easily than polystyrene. The catalysts which effect these selective hydrogenations are made by the reaction of organoaluminum or lithium compounds with transition metal salts of 2‐ethylhexanoic acid.
Effect of dose rate on the radiation‐induced polymerization of ethylene in tert‐butyl alcohol
Authors: Wada Takeshi , Watanabe Terutaka , Takehisa Masaaki
Published: April 2003

The dependence of the dose rate on the rate of radiation‐induced polymerization of ethylene in tert‐butyl alcohol containing 5 vol‐% water was studied. The reaction was carried out by use of a reactor with a capacity of 100 ml under the following conditions: pressure, 200 kg/cm2; temperature, 24 ± 3°C; dose rate, 3.7 × 104−1.6 × 105 rad/hr; amount of medium, 70 ml. The dose rate exponents for rate of the polymerization, the molecular weight, and the number of polymer chain were found to be about 0.8, −0.1, and 0.9, respectively. These results were well explained with kinetic results (obtained by a novel analytical method) for the polymerization which contain both first‐order and second‐order terminations for the concentrations of propagating radical. The individual values of the rate constants in each elementary reaction were also obtained.
Mechanism of action of some stabilizers in the thermal degradation of poly(vinyl chloride)
Authors: Rasuvaev G. A. , Troitskaya L. S. , Troitskiǐ B. B.
Published: April 2003

The dehydrochlorination of PVC under vaccum has been studied at 170–200°C by a volumetric method. The accelerating effect of HCl is related to its interaction with the forming polyene units of macromolecules. A mechanism is proposed. The effects of various stabilizers, such as organic salts of Ca, Ba, Cd, trialkyl‐ and dialkyltin, trialkyl phosphites, and mixtures of phosphites with metal salts upon the rate of dehydrochlorination, polymer crosslinking, and electron absorption spectra of PVC during degradation in evacuated ampoules were investigated. The stabilizing activity of these compounds depends primarily on the effectivity of absorption of HCl and destruction of polyene units by these compounds.