bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on syntheses and permeabilities of special polymer membranes. 48. Transport of organic ions through crosslinked poly(isobutylene‐alternative co‐maleic anhydride) membranes
Authors: Uragami Tadashi , Watanabe Shizuharu , Sugihara Mizuho 
Published: April 2003

AbstractIon exchange membranes with carboxyl groups, which were insoluble in acidic and alkaline aqueous solutions, were prepared from poly(isobutylene‐alternative co‐maleic anhydride) and poly(vinyl alcohol). When a membrane, one side of which was alkaline, the other, acidic, was fixed in a diaphragm cell, it transported organic ions, such as amino acids and aniline, from the acidic to the alkaline side or vice versa. The passage of organic ions through the membrane was governed by an electrochemical interaction between carboxyl groups in the membrance and transporting ions. The direction of the organic ions depended on a pH difference between the two sides of the membrane.
The role of chain transfer agents in the emulsion polymerization of styrene
Authors: Nomura Mamoru , Minamino Yasunobu , Fujita Kazumi , Harada Makoto 
Published: April 2003

AbstractThe effect of chain transfer agents on the nucleation and growth of polymer particles in the emulsion polymerization of styrene were examined extensively. The chain transfer agents used are carbon tetrachloride, carbon tetrabromide, and four primary mercaptans (C2, n‐C4, n‐C7, and n‐C12). It is shown that with an increase in the amount of chain transfer agents charged the rate of polymerization per particle decreases progressively. The number of polymer particles formed, on the other hand, increases initially then decreases. These effects can be enhanced by using a chain transfer agent with higher values of chain transfer constant and solubility in water. It is also demonstrated that with increasing radical desorption from the particles, aided by chain transfer agents, the emulsifier dependence exponent for the number of polymer particles formed increases from 0.6 to 1.0 and the initiator dependence exponent decreases from 0.4 to 0. The effect of chain transfer agents on the nucleation and growth of polymer particles in the emulsion polymerization of styrene can be explained in terms of desorption of chain‐transfered radicals from the polymer particles.
Copolymerization of β‐pinene with styrene oxide and N‐vinylpyrrolidone
Authors: Martínez Francisco , Florsheim René , Martínez Héctor 
Published: April 2003

AbstractThe copolymerization of β‐pinene with styrene oxide (SO) and β‐pinene with N‐vinylpyrrolidone (VP) was investigated by using SnCl4 in dichloromethane diluent at low temperature. Monomer reactivity ratios were evaluated for both copolymers at −80°C; these are r1(SO) = 2.979 and r2(β‐pinene) = 0.002 and r1(VP) = 0.096 and r2(β‐pinene) = 0.294.
Diffusion‐controlled vinyl polymerization. III. Free volume parameters and diffusion‐controlled propagation
Authors: Soh S. K. , Sundberg D. C. 
Published: April 2003

AbstractThe values of the parameters that are necessary to compute the free volume changes accompanying polymerization were determined from viscosity data of concentrated polymer solutions. Relationships applicable above and below the glass transition temperature of the polymer were quantified. A general treatment of the variation of the propagation rate constant with free volume was postulated, based on the variation of the monomeric diffusivity with free volume. This, in turn, was related to the friction coefficient of a polymer chain segment, the values of which are readily available. A discussion of the reaction behavior in the last stage of polymerization and the occurrence of limiting conversion is also presented.
Modification of the wettability of a poly(ethylene terephthalate) film treated by corona discharge in air
Authors: Amouroux J. , Goldman M. , Revoil M. F. 
Published: April 2003

AbstractThe wettability of poly(ethylene terephthalate) films is an important criterion for their industrial use. The attainment of that property is realized by treatment of the material under corona discharge. The purpose of this article is to describe the influence of the principal parameters of the discharge on the modification of the surface properties; the influence was measured by physicochemical methods (ESCA, contact angle). The results prove that the most important physical parameters of the discharge are the wire‐cylinder distance, the current intensity, and the time of treatment. The analysis shows that the fixed species are oxygen and nitrogen in the form of carboxylic functions and amines or nitrogen oxides. In any case, the correlation between free surface energy and concentration of fixed chemical species shows that the surface properties depend on the chemical functions introduced into the material by the discharge.
Model hard segments from diphenyl methane diisocyanate and different chain extenders, and corresponding linear block polyurethanes
Authors: Camberlin Y. , Pascault J. P. , Letoffé J. M. , Claudy P. 
Published: April 2003

AbstractModel hard segments from MDI and different chain extenders have been studied by DSC. Among the studied α‐ω alkane diol‐type chain extenders, all giving crystalline hard segments, butane diol shows the highest melting temperature, while other types such as 1,4‐diaminobutane, 1,4‐benzene dimethanol, and 4,4′‐methylene‐bis(2‐chloroaniline), so‐called MOCA, have no melting endotherm in the range 30–260°C. In addition to DSC, dynamic mechanical properties were measured on linear block polyurethanes having both hard segments and soft ones of hydrogenated 1,2‐polybutadiene. The hard segments in the polyurethane chains are of amorphous structure or low crystallinity, and their high‐temperature behavior depends only on their strength of interaction in the amorphous state. Accordingly, MOCA shows the highest hard‐block softening temperature.
Solvent effect on radical polymerization of butyl acrylate
Authors: Kamachi Mikiharu , Fujii Masakazu , Ninomiya Shin‐Ichiro , Katsuki Shuhei , Nozakura Shun‐Ichi 
Published: April 2003

AbstractThe propagation and termination rate constants kp and kt for the radical polymerization of butyl acrylate initiated by biacetyl have been measured by using the rotating‐sector method, in various solvents at 30°C. The value of kp and initiation rate Ri varied with solvents, while the value of kt did not change with solvents except for benzonitrile. The variation of kp with aromatic solvents has a trend against Hammett σp of the solvent substituents similar to that for methyl methacrylate or phenyl methacrylate except for the value in benzonitrile, when it is larger than the variation for methyl methacrylate or phenyl methacrylate. The larger variation of kp for butyl acrylate is compatible with the view that the origin of the solvent effect lies in complex formation between the propagating radical and aromatic solvent molecules. The exceptional decrease in kp and kt in benzonitrile is explained by a contraction of the poly(butyl acrylate) chain in the poor solvent.
Interaction of Tb(III) and hydrolyzed polyacrylamides in solution as a gel and in the solid state
Authors: Rodrigues Judith Feitosa , Galembeck Fernando 
Published: April 2003

AbstractFormation of the HPAM‐Tb3 complex in solution was observed in the intensification of Tb(III) fluorescence, viscosity, and light scattering. The interaction is dependent on the degree of hydrolysis of the copolymer and the pH of the solution. As the pH value increases, an intensification of the interaction and formation of a gel is observed. The latter was associated with the appearance of crosslinks in which terbium, or one of its hydrolysis products, works as a binding agent between chains. After drying, the characterization of the residues of the gels was effected by analytical determination (C, H, N, Cl, Tb), fluorescence, and infrared spectrophotometry. The analysis and fluorescence revealed the existence of particles of terbium hydroxide; the infrared spectrophotometry showed the binding of terbium (III) to carboxylate of the copolymer.
Acrylonitrile–4‐vinylpyridine copolymers effect of comonomer sequence distribution on properties
Authors: Harris Stephen H. , Gilbert Richard D. 
Published: April 2003

AbstractAcrylonitrile–,4‐vinylpyridine copolymers were prepared in chloroform solution at 60°C with AIBN as initiator. Copolymer compositions were determined from their 15.01‐MHz 13C‐NMR spectra. Reactivity ratios of rAN = 0.093 and r4VP = 0.32 were calculated by the Kelen and Tudos method. The run number, number‐average sequence lengths, and monomer sequence distributions were also calculated. The Tg values of the copolymers, their dye uptake, and degree of alkaline hydrolysis were influenced by the overall copolymer composition but particularly by the monomer sequence distribution in the copolymers.
Analysis of polymers by pyrolysis/chemical ionization mass spectrometry
Authors: Conway D. C. , Marak Roman 
Published: April 2003

AbstractTwo addition‐type polymers, polystyrene and polypropylene, and two condensation‐type polymers, poly(ethylene terephthalate) (Mylar) and poly(hexamethylene adipamide) (nylon‐6,6), were pyrolyzed directly in the ion source of a mass spectrometer by chemical ionization (CI) to reduce fragmentation. The spectra are relatively easy to interpret because most ion peaks occur at a mass corresponding to the ion formula M±H or M + 3H, where M is the formula of a fragment of the original polymer chain. Oligomer peaks were observed for the addition‐type polymers. The intensities of the protonated dimer and monomer were measured as a function of time for styrene (S) and propylene (P). It was found that essentially all the HS+2 was produced by the reaction of HS+ with S, but at least part of the HP+2 was formed by proton transfer to P2. The absence of the analogous reaction in styrene is presumably a result of the reduced volatility of S2.
Plasma polymerization of tetrafluoroethylene. IV. Comparison of ethylene and tetrafluoroethylene by measurement of electron temperature and density of positive ions
Authors: Yanagihara Kenji , Yasuda H. 
Published: April 2003

AbstractThe double probe method was applied to plasma of tetrafluoroethylene (TFE) and ethylene and the electron temperature (Te) and density of positive ions (np) were measured at various discharge wattages. The probe current‐probe voltage diagrams for TFE were different from those for ethylene. The shape of its diagram indicates that a considerable number of negative ions exist in TFE plasma. The levels of np for TFE were also nearly six times greater than those for ethylene at the same discharge current. The dependence of TFE polymer deposition and the chemical structure of the polymer, based on ESCA data on discharge current, was related to Te and np measured by the probe method. The values of Te and np may not be directly related to the polymer formation in a plasma; the method provides a direct measure of plasma energy density where plasma polymerization takes place, whereas it cannot be accurately estimated by the input energy of a discharge. It was found that plasma energy density based on (npTe) for TFE plasma and that for ethylene differ significantly at the same level of input parameter (W/FM), where W is the discharge wattage, F is the volume flow rate, and M is the molecular weight of the monomer.
Gamma radiation‐induced bulk polymerization of some methyl aryloxymethacrylates
Authors: Devarajan R. , Balakrishnan T. , Santappa M. , Viswanathan B. 
Published: April 2003

AbstractThe kinetics of γ‐radiation‐induced bulk polymerization of methyl phenoxymethacrylate and methyl paracresoxymethacrylate was studied at dose rates of 0.3 and 0.075 Mrad/h and at temperatures of 0 and 30°C. The polymerization was first order with respect to the monomers and the rate of polymerization had a direct dependence on dose rate. The activation energy value for the polymerization of methyl phenoxymethacrylate was 1.2 and 0.7 kcal/mol for methyl paracresoxymethacrylate. The polymerization proceeded predominantly by an ionic mechanism.
Poly‐Schiff bases. I. Preparation of poly‐Schiff bases from 4,4′‐diacetyl diphenyl ether (DDE) with various diamines
Authors: Patel M. S. , Patel S. R. 
Published: April 2003

AbstractThermally stable and semiconducting poly‐Schiff bases are synthesized by condensing 4,4′‐diacetyl diphenyl ether with o‐, m‐, and p‐phenylene diamines, benzidine, and ethylene diamine under different experimental conditions. These bases are insoluble in common organic solvents. They are characterized by infrared (IR) and viscosity measurements, thermal analysis, and the study of electricel properties at various temperatures. Variation of electrical conductivity σ with temperature followed the empirical relation σ = σ0e−E*/kT.
Amphiphilic block copolymer of 9‐vinylphenanthrene and methacrylic acid: Fluorescence quenching of phenanthrene residue in aqueous medium
Authors: Morishima Yotaro , Itoh Yoshihiro , Hashimoto Toshihiko , Nozakura Shun‐Ichi 
Published: April 2003

AbstractAmphiphilic block copolymers of 9‐vinylphenanthrene (VPh) and methacrylic acid (MA) were prepared by a two‐step living anionic polymerization of VPh and trimethylsilyl methacrylate followed by hydrolysis of the trimethylsilyl ester groups. Bis(2‐hydroxyethyl) terephthalate, an oxidative quenching agent with amphiphilic nature, strongly quenched the fluorescence of phenanthrene groups in the block copolymer in aquecus solution. Apparent second‐order rate constants kq for the quenching ranged in the magnitude of 1011−1012M−1 s−1 in the borate (pH 9) and phosphate (pH 7) buffers, whereas those in DMF solution were found to be ∼109M−1 s−1. No such difference in kq for the aqueous and DMF solutions was observed with the related random copolymer. The results suggest that a considerable increase in the effective concentration of the quencher around the VPh sequences in the block copolymer resulted from hydrophobic association. Fumaric acid (FA), an anionic quencher, did not quench the fluorescence of the copolymer at pH 9 and 7, presumably because of the lack of accessibility of the quencher to the copolymer due to electrostatic repulsion. However, in neat water in which only a part of the carboxyl groups of MA sequences are dissociated and therefore the charge effect is minimized, FA quenched the fluorescence, with the kq value approximating the diffusion control limit.
Photopolymerization initiated by charge transfer complex. II. Photopolymerization of methyl methacrylate with the use of γ‐picoline–bromine charge transfer complex as photoinitiator
Authors: Lenka Subasini , Nayak Padma L. 
Published: April 2003

AbstractPolymerization of MMA was carried out in the presence of visible light (440 nm) with the use of γ‐picoline‐bromine charge transfer complex as the initiator. The rate of polymerization Rp increases with increasing monomer concentration and the monomer exponent was computed to be unity. The rate of polymerization increases with increasing initiator concentration. The initiator exponent was computed to be 0.5. The reaction was carried out at three different temperatures and the overall activation energy was calculated to be 4.5 kcal/mol. The polymerization was inhibited in the presence of hydroquinone. Kinetic and other evidence indicates that the overall polymerization takes place by a radical mechanism.
Spectroscopic examination of polyethylenimine backbone polynucleotide models
Authors: Ludwick Adriane G. , Overberger C. G. 
Published: April 2003

AbstractThe UV absorptions of nucleic acid analogs with a polyethylenimine (PEI) backbone and uracil‐ and thymine‐containing pendants have been examined. For the solvents used (water, basic aqueous solutions, and DMSO), significant hypochromicity is observed. The uracil‐containing polymers have been shown to interact with polyA in an aqueous solvent at pH 7 (tris buffer). The interaction is proportional to the size of the polymer. A correlation is attempted between the properties of the analogs and their biological activity.
Ring‐opening polymerization of 5,6‐anhydro‐glucose and ‐allose derivatives. Effect of substitutional or configurational difference at the position of sugar monomers on polymerization behavior
Authors: Uryu Toshiyuki , Kitano Kissho , Matsuzaki Kei 
Published: April 2003

AbstractThe ring‐opening polymerization of 5, 6‐anhydro sugar derivatives, which are substituted oxiranes, was carried out to obtain (5→6)‐glycan derivatives and to elucidate the reactivities of the monomers. 5,6‐Anhydro‐3‐O‐benzyl‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (BAIGF) (1), 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐allofuranose (AIAF) (2), and 5,6‐anhydro‐3‐O‐benzyl‐1,2‐O‐isopropylidene‐α‐D‐allofuranose (BAIAF) (3) were used for polymerization. The monomer 1 was polymerized by anionic catalysts KOH and tert‐BuOK in high yield, while cationic catalysts gave polymers in low yield. On the other hand, the monomer 2 was polymerized by a variety of Lewis acids and strong bases as catalyst in high yield. The monomer 3 was polymerized by anionic catalyst into insoluble polymer. The polymers anionically obtained from these monomers have stereoregular structures composed of CH2CHRO backbone, but the degree of polymerization was limited below 20 by various factors such as termination and chain transfer. The effects of substitution and difference of the configuration at position 3 on polymerization behavior were elucidated by comparing the polymerizabilities and the polymer structure prepared from these monomers with those from 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (AIGF) (4). In addition, copolymerization of AIGF with AIAF was carried out using PF5 and NaOH as catalysts in order to examine the difference in monomer reactivity, giving rAIGF = 0.81 and rAIAF = 0.29 for the anionic polymerization.
Functional polymers. XIII. Synthesis and polymerization of 2(2‐hydroxy‐5‐methylphenyl)‐5‐vinyl‐2H‐benzotriazole
Authors: Yoshida Shohei , Lillya C. Peter , Vogl Otto 
Published: April 2003

AbstractThe synthesis of 2(2‐hydroxy‐5‐methylphenyl)‐5‐vinyl‐2H‐benzotriazole was accomplished in seven steps starting from 4‐ethylaniline. Acetylation and nitration followed by hydrolysis gave 2‐nitro‐4‐cthylaniline which was diazotized, condensed with p‐cresol, and reduced to 2(2‐hydroxy‐5‐methylphenyl)‐5‐ethyl‐2H‐benzotriazole. As in previous cases, the ethyl group was transformed to the vinyl compound by bromination with N‐bromosuccinimide and dehydrobromination of the 1‐bromoethyl compound. Monomer grade 2(2‐hydroxy‐5‐methylphenyl)‐5‐vinyl‐2H‐benzotriazole was polymerized and copolymerized with styrene, methyl methacrylate, and n‐butyl acrylate.
Synthesis of hydroxyl‐terminated polycarbonates of controlled number‐average molecular weight
Authors: Riffle J. S. , Shchori E. , Banthia A. K. , Freelin R. G. , Ward T. C. , McGrath J. E. 
Published: April 2003

AbstractHydroxyl‐terminated polycarbonates are important starting materials for the synthesis of multiblock copolymers. Earlier papers from our laboratory and elsewhere have demonstrated their utility in siloxane, aryl ether, and ester systems. One synthesis problem that must be addressed is the control of the number‐average molecular weight and hence block size of the polycarbonate oligomeric precursor. The facile phosgene‐hydroxyl reaction is often difficult to monitor precisely. The present article describes a novel, simple, and convenient technique for the synthesis of hydroxyl‐terminated polycarbonates of well‐controlled number‐average molecular weight. The approach involves an in situ blocking of some of the phenolic groups either prior to or during phosgenation. The protecting groups are easily removed after the polymerization is complete. In a practical laboratory experiment the technique does not require any additional step beyond that necessary for the preparation of nonfunctional polycarbonates of controlled molecular weight. The method is demonstrated in this article with the polycarbonate of bisphenol‐A via the use of trimethylchlorosilane, trifluoroacetic anhydride, and trifluoroacetic acid as blocking groups. Ultraviolet, 19F‐NMR, and 1H‐NMR measurements as well as vapor‐pressure osmometry were used to characterize the oligomers.
The action of a benzotriazole light stabilizer in wool. II. The mechanism of photostabilization
Authors: Leaver Ian H. 
Published: April 2003

AbstractA study was made of the photoprotective effect of a sulfonated hydroxyphenylbenzotriazole light stabilizer in wool fabric. Investigations of the absorption, luminescence quenching, and photostabilizing properties of the benzotriazole showed that optical screening is the key mode of operation. Excited‐state quenching is of little practical importance. The protective effect of the stabilizer is strongly dependent on the exposure conditions. There is a good correlation between UV screening ability and photoprotection at wavelengths near 300 nm where the fiber has maximum photosensitivity but the correlation in the spectral region of 314–390 nm is poor. The failure of the benzotriazole to provide good protection in the near‐UV region of the spectrum is attributed mainly to the sensitizing action of a small number of fluorescent molecules of the stabilizer, the internal hydrogen bond of which has been disrupted by the influence of the polar environment of the substrate.
Magnesium‐chloride‐supported high‐mileage catalysts for olefin polymerization. II. Reactions between aluminum alkyl and promoters
Authors: Chien James C. W. , Wu Jiun‐Chen 
Published: April 2003

AbstractThe reactions between AlEt3 and the modifiers, promoters, and coactivators of a typical magnesium‐chloride‐supported, high‐activity propylene polymerization catalyst were studied. Infrared, MS analysis of the gas evolved, and GC–MS of the hydrolysis products for the reaction between AlEt3 and p‐cresol showed rapid and quantitative reactions with p‐cresol either in the support or solution. The reaction products from AlEt3 and esters were hydrolyzed, acidified, and dehydrated. The resulting carbonyl and olefinic compounds were identified by GC–MS. Proton and carbon nuclear magnetic resonance (NMR) techniques were also used to study these reactions. The expected intermediates were found in the PMR and CMR spectra. The mechanisms of reactions were proposed. The results of this study showed that when AlEt3 and esters are used as coactivators reaction products that can significantly influence the performance of the catalyst are formed.
Magnesium‐chloride‐supported high‐mileage catalysts for olefin polymerization. III. Electron paramagnetic resonance studies
Authors: Chien James C. W. , Wu Jiun‐Chen 
Published: April 2003

AbstractElectron paramagnetic resonance (EPR) was used to study a MgCl2‐supported, high‐mileage olefin polymerization catalyst. Anhydrous Toho MgCl2 was the starting material. Treatment with HCl at an elevated temperature, ethyl benzoate by ball‐milling, p‐cresol, AlEt3, and TiCl4produced a catalyst that contained a single EPR observable Ti+3 species A, which was strongly attached to the catalyst surface, had a D3h symmetry, and no other Ti+3 ion in an immediately adjacent site. Species A constitutes only 20% of all the trivalent titaniums; the remainder is EPR‐silent and may be attributed to those Ti+3 ions that have adjacent sites occupied by one or more Ti+3 ions. Activation with preformed AlEt3/methyl‐p‐toluate complexes produced a single Ti+3 species (C) with rhombic symmetry and displaying 27Al superhyperfin splitting which has attributes for a stereospecific active site. This species is unstable under polymerization conditions and is transformed to another species with axial symmetry and solubilization. Both processes could lead to catalyst deactivation and loss of stereospecificity. Catalysts activated by AlEt3 and methyl‐p‐toluate separately in various sequential orders produced a multitude of EPR‐observable Ti+3 species with varying degrees of motional freedom deemed detrimental to stereospecific polymerization of α‐olefins.