bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of methyl methacrylate induced with the peracid‐type ion exchange resin
Authors: Koyama Kiyoshi , Nishimura Masato , Hashida Isao 
Published: April 2003

AbstractThe polymerization of methyl methacrylate initiated with a peracid‐type resin was studied. The peracid‐type resin was prepared by the oxidation of cation‐exchange resin (Amberlite IRC‐50) with 60 wt‐% aqueous hydrogen peroxide in the presence of p‐toluenesulfonic acid. It was found that the peracid‐type resin was effective as an initiator for polymerization of methyl methacrylate. The kinetic investigation indicated that this polymerization proceeded by a radical mechanism, and the overall activation energy of polymerization was 15.8 kcal/mole. No effect of macromolecular catalyst on steric structure of the resulting polymer was observed. Some graft polymer was formed in bulk polymerization. On the other hand, only a homopolymer was obtained in solution polymerization. From the results obtained, a possible mechanism of initiation with the peracid‐type resin is proposed and discussed.
Ring‐opening polymerization of ethylene organophosphorothioates: Stereoregular polymerization involving asymmetry at phosphorus
Authors: Vandenberg E. J. 
Published: April 2003

AbstractStereoregular polymerization involving asymmetry at phosphorus has been obtained from ethylene methyl or phenyl phosphorothioate with R2MgNH3 catalysts, or, in some cases, with R2Mg alone. The methyl ester gave two types of polymer: an amorphous rubber and a low‐melting (75°C) crystalline polymer. The phenyl ester gave mainly a low‐melting (68°C) crystalline polymer of 2.2 inherent viscosity. Proton and 31P NMR and infrared spectra of these polymers are in accord with the expected chain unit, CH2CH2OP(S)(OR)O. The polymerization mechanism probably involves an anionic ring‐opening step with PO cleavage. Ring opening with CO cleavage appears to be largely excluded. This conclusion is based on the expectation that anionic ring opening with CO cleavage should lead to a rearranged chain unit, CH2CH2OP(O)(OR)S, because of the high nucleophilicity of sulfur as compared with oxygen. Proton and 31P NMR spectra give no evidence for the rearranged unit within the limit of detection (ca. 3%). However, on aging, the methyl ester polymer changes drastically to form up to 40% CH2SP groups. Presumably, the polymer undergoes the well‐known thiono‐thiolo rearrangement characteristic of simple phosphorothioate esters to form CH2CH2OP(O)(SCH3)O chain units. The phenyl ester polymer is stable under the same aging conditions.
Structural changes in polymers of diethyl succinylsuccinate(1,4‐diethoxycarbonyl‐2,5‐dihydroxy‐1,4‐cyclohexadiene) with diamines at high temperatures
Authors: Tai Akira , Higashi Fukuji , Yokomizo Soichiro 
Published: April 2003

AbstractThe structural changes of the polymers having the following structures:
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at high temperatures were studied by the spectroscopic and thermal analysis. When the polymers were heated in air, they were oxidized predominantly to polymers having the structure:
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The rate of oxidation was fast and the reaction was almost completed within 2 hr at 180°C. In the case of polymer 3, an intramolecular cyclization to form acridone was detected as a minor reaction.
Studies on adsorption of natural and synthetic hymatomelanic acids at air–water and at oil–water interfaces
Authors: Ghosh Kunal , Chatterjee B. C. , Mukherjee S. K. 
Published: April 2003

AbstractBy utilizing a static method, based on slight modification of the Wilhelmy plate method, the interfacial properties of one natural and two synthetic hymatomelanic acids were studied at both the air–water and oil–water interfaces. On this basis their number‐average molecular weights, flexibility and shape of the macromolecular chains at the interface, and the related thermodynamic parameters were evaluated.
Solid‐state polymerization of vinylpyridine coordination compounds
Authors: Agnew N. H. , Brown M. E. 
Published: April 2003

AbstractA survey of the solid‐state polymerizability of 2‐ and 4‐vinylpyridine (Vpy) complexes of divalent cobalt, nickel, copper, and zinc chlorides has been carried out. The influence of metal ion, ligand, coordination stereochemistry, and crystal structure is discussed. The tetrahedral modification of the complex Co(4‐Vpy)2Cl2 has been found to undergo a particularly facile thermal polymerization below its melting point to yield high molecular weight poly‐4‐vinylpyridine. The polymer is shown to be conventional atactic head‐to‐tail poly‐4‐vinylpyridine. Thermogravimetric methods and optical microscopy have been used to study the thermal polymerization of single crystals of the complex. Results indicate a diffusion‐controlled mechanism in which defective regions in the crystal act as nuclei for the polymerization.
Concentration effects in gel‐permeation chromatography
Authors: Rudin Alfred 
Published: April 2003

AbstractPeak elution volume in gel‐permeation analysis of polymers depends on sample concentration as well as molecular weight. Elution volume is related to the logarithm of the hydrodynamic volume of the solvated polymer species. The hydrodynamic volume of a given species is, in turn, inversely related to the concentration. Since molecular weight and concentration are interacting variables, the elution volume–molecular weight relation is not uniquely determined. A model is presented which accounts quantitatively for concentration effects, using parameters which are available a priori. The data required are polymer molecular weight, concentration, and density and the Mark‐Houwink relation for the particular polymer‐solvent combination.
Study of the γ‐alumina polymerization of furfuryl alcohol
Authors: Wewerka E. M. 
Published: April 2003

AbstractThe γ‐alumina polymerization of furfuryl alcohol produces a polymer differing in structure from that obtained by polymerization with acid catalysts. In order to gain a better understanding of the basic chemistry of this method of polymerization furfuryl alcohol, studies were done, both with γ‐alumina‐polymerized and acid‐polymerized furfuryl alcohol resins, concerning both the chemical nature of the resin constituents, and the manner in which these constituents affect resin molecular size distribution as measured by gel permeation chromatography. Because of numerous side reactions, the γ‐alumina polymerization of furfuryl alcohol was found to result in the early elimination of many of the molecules containing functional groups necessary to the sustenance of polymerization. As a consequence even at advanced degrees of polymerization there remain relatively large amounts of low molecular weight components that have not further polymerized. At the higher degrees of polymerization, the high molecular weight end of the resin molecular size distribution was observed to be significantly enhanced over that of the acid‐polymerized resins. The latter behavior is attributed to the occurrence of crosslinking reactions made possible by the higher temperature required for polymerization with γ‐alumina. It is further concluded that the curing processes of γ‐alumina‐polymerized furfuryl alcohol resins proceed by a mechanism unlike that of the acid‐polymerized resins.
Studies on substituted lactams (I)
Authors: Klein K. P. , Reimschuessel H. K. 
Published: April 2003

AbstractSyntheses and reactions of 4‐carboxy‐2‐pyrrolidone, 6,6‐dimethyl‐4‐carboxy‐2‐piperidone, and 5,5‐dimethyl‐4‐carboxy‐2‐pyrrolidone are described. Whereas 4‐carboxy‐2‐pyrrolidone polymerizes upon heating to form a polyimide, the two lactams containing geminal dimethyl groups undergo isomerization. The 6,6‐dimethyl‐4‐carboxy‐2‐piperidone isomerizes to 5,5‐dimethyl‐3‐carboxymethyl‐2‐pyrrolidone, and 5,5‐dimethyl‐4‐carboxy‐2‐pyrrolidone affords isopropylidene succinimide. Possible mechanisms for these reactions are discussed.
Friedel‐crafts copolymerization of thiophene and p‐di(chloromethyl)benzene. II. Products of the later stages of the reaction
Authors: Grassie N. , Colford J. B. 
Published: April 2003

AbstractProducts of the copolymerization of thiophene and p‐di(coloromethyl)benzene in presence of stannic chloride have been separated by using gel‐permeation chromatography (GPC) and identified by using principally mass, infrared, and nuclear magnetic resonance spectroscopy. The GPC separation is not nearly as efficient as the separation of the products of the corresponding benzene–DCMB and diphenylmethane–DCMB reactions which have previously been described. A further complication which makes a kinetic analysis of this reaction more difficult is the occurrence of intramolecular condensation of certain of the earlier products leading to cyclic structures incorporating four aromatic rings. These investigations have made it possible to deduce some of the principal structural differences between the thiophene–DCMB and benzene–DCMB polymers which may have some bearing on the differences which have been found in their thermal stabilities.
Synthesis of phosphorus‐containing poly‐o‐acylamideoximes from polyacrylonitrile
Authors: Carraher Charles E. , Wang Long‐Shyong 
Published: April 2003

AbstractThe synthesis of phosphorus‐containing poly‐O‐acylamideoximes from polyacrylonitrile has been accomplished by the reaction sequence:
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Reaction is believed to occur at the NH2 nitrogen as well as at the oxime group, but reaction is not believed to occur at both groups in the amide oxime unit. Inclusion of the phosphorus moiety occurs in the medium to high range.
Preparation and polymerization of N‐(1,1‐dimethyl‐3‐hydroxybutyl) acrylamide and N‐(1,1‐dimethyl‐3‐hydroxybutyl)methacrylamide
Authors: Hoke Donald I. 
Published: April 2003

AbstractThe syntheses of N‐(1,1‐dimethyl‐3‐hydroxybutyl)acrylamide and the corresponding methacrylamide by reduction of the oxobutyl acrylamides are described. These monomers are colorless liquids which are soluble in water and many organic solvents. They polymerize readily to form homopolymers and copolymers with other vinyl monomers. The preparation of polymers containing these repeating units by reduction of polymers of diacetone acrylamide and diacetone methacrylamide is also described.
Snake‐cage redox polyelectrolytes based on anion‐exchange resins
Authors: Kessick M. A. 
Published: April 2003

AbstractRedox polyelectrolytes are described where the polyphenols hydroquinone, pyrogallol, and catechol were absorbed as counterions by a strong base anion‐exchange resin in the hydroxide form, and then polymerized by refluxing in 1:1 mole ratio with formaldehyde in aqueous solution, thus producing a “snake‐cage” configuration. The redox capacities of the resins were determined by oxidation with iodine/iodide solution, and found to approach theoretical at between 5.1 and 5.4 meq/g. The rate of oxidation was found to be controlled by diffusion within the particles. Fe3+ was unsatisfactory as an oxidant, owing to the exclusion effect by the fixed positive charges in the resin matrix. At low pH the resin beads were light to reddish brown in the reduced form, black in the oxidized form. The resins, especially that based on catechol, showed much greater stability in 1N NaOH solution than simple polyphenol–formaldehyde condensation polymers.
Electroinitiated polymerization of vinylic monomers in polar systems. III. Polymerization of acrylates and methacrylates in alcohol solutions
Authors: Albeck Michael , Relis Joseph 
Published: April 2003

AbstractMethyl, ethyl, and n‐butyl acrylates and methacrylates are polymerized by electroinitiation in methanol–, ethanol–, and n‐propanol–electrolyte mixtures in which the monomers are soluble whereas the polymers obtained are insoluble. The technique of changing the polarity of the electrodes described earlier was used. The relationships between molecular weights and polymer yields as function of current density, initial monomer concentration and dielectric constant of the solvent are described. A kinetic scheme for the initiation, propagation, and termination is given.
Hydrodimerization in liquid ammonia
Authors: Rosen H. , Levy M. 
Published: April 2003

AbstractThe hydrodimerization of acrylonitrile (M1), ethyl acrylate (M2), and α‐methyl acrylonitrile (M3) in liquid ammonia by Na amalgam was studied. It was found that the concentration of phenol, as protonating agent, affects the rate of electron transfer from the amalgam to the monomer. This was explained by assuming the active species to be the protonated monomer complex MH+. Cross hydrodimerization rate constants were measured for the three monomers. The values of the ratios obtained were: k11/k12 = 0.89, k22/k21 = 0.39, k11/k13 = 5.8, k33/k31 = 0.12, k22/k23 = 1.7, k33/k32 = 0.36.
1,4 polymerization of isoprene by titanate catalyst systems
Authors: Horne Samuel E. , Carman Charles J. 
Published: April 2003

AbstractTitanates are versatile in the 1,4 polymerization of isoprene. The (R′O)4Ti/RAlCl2 catalyst gives either cis‐ or trans‐1,4‐polyisoprene, depending on the nature of both the titanate and the solvent. Primary titanates give cis‐1,4‐polyisoprene in both aliphatic and aromatic solvents. Secondary titanates give cis‐polyisoprene in aliphatic solvents, and trans‐1,4‐polyisoprene in aromatic solvents. Tertiary titanates give trans‐polyisoprene in both aliphatic and aromatic solvents. A mechanism is postulated which takes into consideration the role of the solvent. ESR studies of the various titanate–RAlCl2 catalysts were made; the paramagnetic structures are related to polymerization mechanisms.
Structure and property relationships in ethylene–vinyl acetate copolymers
Authors: Salyer I. O. , Kenyon A. S. 
Published: April 2003

AbstractThe effects of vinyl acetate content on crystallinity of ethylene–vinyl acetate (E/VA) copolymers were investigated by x‐ray diffraction and differential thermal analysis (DTA). The values of these parameters obtained from DTA were found to agree quantitatively with data calculated from x‐ray, probability equations, and copolymer theory. The melting points of the crystalline copolymers, and the molar amounts of vinyl acetate to produce a completely amorphous rubber corresponds exactly to that predicted by the Flory theory. The random character expected in E/VA copolymers is thereby confirmed. The physical properties of E/VA copolymers of all ranges of compositions and crystallinity were determined. Depending directly upon vinyl acetate content, the copolymers changed progressively from highly crystalline polyethylene to semicrystalline polyethylene, a completely amorphous rubber, a soft plastic with a glass transition near room temperature. Properties which were correlated with copolymer composition include: crystallinity, melting point, density, modulus, tensile strength, glass transition, and solubility. Finally, the effect on crystallinity and physical properties of replacing the acetoxy group in E/VA with the smaller, highly polar hydroxyl group (ethylene—vinyl alcohol copolymer) was also investigated.
Reactions of some organic peroxides with triphenylphosphine and sodium dialkyl phosphites
Authors: Jarvie A. W. P. , Moore C. G. , Skelton D. 
Published: April 2003

AbstractThe reactions of the allylic peroxides ascaridole, cyclohexadiene endoperoxide, and α‐phellandrene peroxide with triphenylphosphine follow an SNi'‐type mechanism. In contrast, the acyclic allylic compounds, allyl tert‐butyl peroxide, α‐cumyl cyclohexenyl peroxide, and tert‐butyl cyclohexenyl peroxide apparently react with triphenylphosphine by a free‐radical mechanism. The saturated cyclic peroxide dihydroascaridole, in which there is no possibility of an allylic rearrangement, gives with triphenylphosphine a mixture of olefinic alcohols. Di‐n‐butyl peroxide is readily cleaved by sodium dialkyl phosphites, but sterically hindered peroxides do not react under similar conditions. Reaction can, however, take place at the oxygen adjacent to a large group if a smaller substituent is present on the other oxygen atom.
Kinetic study of ethylene polymerization with chromium oxide catalysts by a radiotracer technique
Authors: Zakharov V. A. , Ermakov Yu. I. 
Published: April 2003

AbstractThe quenching of polymerization with a chromium oxide catalyst by radioactive methanol 14CH3OH enables one to determine the concentration of propagation centers and then to calculate the rate constant of the propagation. The dependence of the concentration of propagation centers and the polymerization rate on reaction time, ethylene concentration, and temperature was investigated. The change of the concentration of propagation centers with the duration of polymerization was found to be responsible for the time dependence of the overall polymerization rate. The propagation reaction is of first order on ethylene concentration in the pressure range 2–25 kg/cm2. For catalysts of different composition, the temperature dependence of the overall polymerization rate and the propagation rate constant were determined, and the overall activation energy Eov and activation energy of the propagation state Ep were calculated. The difference between Eov and Ep is due to the change of the number of propagation centers with temperature. The variation of catalyst composition and preliminary reduction of the catalyst influence the shape of the temperature dependence of the propagation center concentration and change Eov.
Polysulfone–polydimethylsiloxane block copolymers
Authors: Noshay A. , Matzner M. , Merriam C. N. 
Published: April 2003

AbstractAlternating block copolymers have been synthesized from dihydroxyl‐terminated polysulfone and bis(dimethylamine)‐terminated polydimethylsiloxane oligomers. The products are soluble, amorphous, and transparent, and display excellent thermal and hydrolytic stability. Elastomeric and rigid compositions can be prepared by varying oligomer molecular weight. Copolymers made with oligomers of ≥ 5000 molecular weight are two‐microphase systems which display glass transition temperatures at −120°C and at +160°C, and therefore have a wide useful temperature range.
Novel aliphatic polymers containing imide ring. I. Polyspiroimide based on methanetetraacetic acid
Authors: Lee Lester T. C. , Pearce Eli M. , Hirsch Stephen S. 
Published: April 2003

AbstractHigh molecular weight polyspiroimides have been prepared by reacting diamines with the dianhydride of carboxymethanetetraacetic acid in polar organic solvents. Alternatively, thermal condensation of the preformed salt made from equimolar amounts of diamine and methanetetraacetic acid (MTA) can be used. These all‐aliphatic polyimides are soluble in certain organic solvents, and possess good thermal‐oxidative stability.
Characterization of the collagen–vinyl graft copolymers prepared by the ceric ion method. I. Solution properties
Authors: Rao K. Panduranga , Joseph K. Thomas , Nayudamma Y. 
Published: April 2003

AbstractGraft copolymerization of vinyl monomers on to collagen was carried out by the ceric ion method. The grafted vinyl polymer chains were isolated by both acid and enzymatic hydrolysis of the collagen backbone in order to characterize the graft copolymers. Proof of grafting was obtained through the detection of amino acid endgroups in the grafts isolated by both the methods. The grafts isolated gave the characteristic blue color normally associated with the presence of amino acids. The presence of amino acid endgroups was further confirmed by dinitrophenylation of the isolated grafts. The absorption spectra of the dinitrophenylated(DNP) grafts showed absorption maximum in the ultraviolet region of 340–360 mμ, characteristic of DNP‐amino acids. Soluble collagen grafted with polyacrylamide(PAA) formed fibrils on heating to 37°C at neutral pH but, unlike the native collagen, these fibrils did not redissolve on cooling at 2°C. These results show that the redispersion property of soluble collagen was impaired, probably by attachment of the PAA side chains to the collagen molecule. The turbidimetric titration behavior of the grafts, their general behavior of swelling in different solvents, and the intrinsic viscosity of the copolymers in mixed solvents also provided additional proof of grafting.
Grafting of methyl methacrylate and its derivatives onto blood
Authors: Kojima Kuniharu , Iwabuchi Susumu , Kojima Koichi , Tarumi Niro , Masuhara Eiichi 
Published: April 2003

AbstractThe grafting of vinyl monomers by tri‐n‐butylborane to blood has been investigated. The infrared spectra indicated that the monomers were grafted onto blood components. The grafting seems to occur onto blood proteins, mainly onto hemoglobin. The presence of water was essential to the grafting. The hydrolysis of the graft suggests that basic amino acids in the blood proteins, such as lysine and histidine, play an important role in the grafting.
Crosslinking and structural changes of cellulose fibers
Authors: Nikonovich G. V. , Usmanov Kh. U. 
Published: April 2003

AbstractThe supermolecular structure of various cellulose fibers modified with crosslinking reagents has been investigated by electron microscopy methods. The density, degree of crystallinity (DC), and length changes in alkaline solutions were measured for the modified celluloses. The samples treated with monofunctional analogs of the crosslinking reagents as well as the fiber preparations containing linear and network polymer were also investigated. Three main problems are suggested for the discussion: (1) the general regularities of the structural changes in cellulose in the process of crosslinking; (2) the specific features of the structural changes, as observed in different cellulose samples; (3) the relation between the degree of modification, the type of modifying reagent, and the structure of the crosslinked cellulose. The characteristic structural changes, i.e., the increase in the thickness of fragments, the specific cogged edges, the increase in the lateral dimensions of structural elements all seem to be most representative in native cellulose fibers and are perfectly well distinguished. Similar changes are found in viscose fibers but are less clearly defined. Crosslinking proceeds rather uniformly through the whole of the fiber cross section. It appeared to be most evident when the cross sections are treated with solvents, or when etched in gaseous discharge. Only in cases when the modification is performed in nonaqueous solutions does the reaction proceed mainly in the peripherial regions of the fiber. In fibers subjected to strong swelling, crosslinking results in a real increase in the lateral dimensions of the microfibrils, with the layer thicknesses remaining the same. As a rule, the modification does not imply significant changes in the fiber surface. The crystallite size decreases in the process of crosslinking. This appears to be peculiar to viscose fibers, especially to those subjected to crosslinking in the swollen state. The degree of crystallinity and density of the fibers decrease sharply, which seems to be especially evident in epichlorohydrin‐modified samples. Cellulose structure remains unchanged when linear or network polymer forms in the fiber or when the samples are treated with monofunctional reagents. Changes in properties and structure of cellulose caused by crosslinking are most apparent if elongation of the fibers in alkaline solution before and after the modification is compared.
Quantitative treatment of the dye partition method of analysis of surfactants and of ionic groups in high polymers
Authors: Mandal B. M. , Palit S. R. 
Published: April 2003

AbstractA quantitative treatment of the extraction of ionic dyes from aqueous solutions into organic solvents of low dielectric constant by surfactants or polymers with ionic groups having a charge opposite to that of the dye ion, is presented. The assumption is made that the extracted species are ion‐paired in the organic phase. Based on this, a graphical extrapolation method is suggested for the quantitative estimation of ionic groups in polymers. Theoretically, the method should yield quantitative results irrespective of polymer chain length and character. This method of analysis does not require any calibration data.