bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of solvent for vinyl acetate polymerization on microstructure of poly(vinyl alcohol)
Authors: Imai Kiyokazu , Shiomi Tomoo , Oda Naonobu , Otsuka Hideo 
Published: April 2003

AbstractThe solution polymerization of vinyl acetate was carried out in several solvents at 0 to 100°C, using 2,2′‐azobisisobutyronitrile as initiator. For the resulting poly(vinyl alcohol) (PVA), iodinecoloration, 1,2‐glycol structure and tacticity were observed. The pentad tacticity of PVA was estimated from its methine carbon spectra by means of 13C‐FTNMR spectrometer. Iodine‐coloration ability of PVA varied markedly with the type of polymerization solvent and decreased in the following order: phenol > aq. phenol > methyl alcohol > ethyl acetate > DMSO, ethylene carbonate. The syndiotactic fraction in PVA also decreased with polymerization solvent in the same order as that of iodine coloration, while 1,2‐glycol content of PVA was not almost affected by polymerization solvent except for phenol and aq. phenol. In solution polymerization performed, effect of polymerization temperature on tacticity was less than that of solvent.
Plasma‐substrate interaction: Effect of volatile oligomers in silicone rubber on plasma polymerization of fluorine‐containing monomers
Authors: Yeh Y. ‐S. , Yasuda H. 
Published: April 2003

AbstractThe cause of the conspicous Si content consistently observed on plasma polymers deposited on silicone rubber was investigated in this study. Plasma polymers of tetrafluoroethylene and of hexafluoroethane were deposited on the inside surface of Silastic tubings with and without oligomers by using a semicontinuous plasma polymerization reactor. This tube coating reactor is unique in the sense that the only surface which interacts with the plasma is the substrate surface (i.e., inside wall of tubing) and that plasma polymerization occurs in a very small volume of 3.3‐mm‐I.D. and 2‐cm‐long section of tubing at any given time. These two factors render the reactor a suitable system for the investigation of plasma‐substrate surface interaction. Silastic tubings free of oligomers were prepared by extracting the tubings as received with distilled n‐hexane for 3 h which yielded a 3% weight loss. It was found that the conspicuous Si content noted previously was not occasioned by the migration of oligomers through the plasma polymers but was caused by the redeposition of plasma copolymers formed from a mixture of the feed‐in monomer and the silicon‐containing volatile components evolved from the silicone rubber when exposed to the plasma. The presence of Si‐containing compounds in the plasma evidently interfered with the plasma polymerization of tetrafluoroethylene and hexafluoroethane. Without volatile oligomers (the extracted samples), ESCA analysis indicated that the plasma polymers contained large amounts of CF3, CF2, and CF moieties, just like most typical plasma polymers of these monomers deposited on nonreactive substrates. With the presence of volatile oligomers, the fluorine content decreased drastically and a significant increase of oxygen‐containing and silicon‐containing moieties was observed. The influence of the volatile oligomers in the substrate on the balance between ablation and polymerization in plasma polymerization and its energy input level dependence (manifested by W/FM) were studied as well. The results were also discussed in relation to the bicyclic rapid step‐growth polymerization mechanism.
Use of cyclohexanone oxime as an oxidant in redox polymerization: Kinetics of oxidation and polymerization
Authors: Varaprasad D. V. P. R. , Mahadevan V. 
Published: April 2003

AbstractCyclohexanone oxime was employed as an oxidant in combination with Vanadium (III) as a redox initiator system for the polymerization of AN and MMA. Kinetics were investigated in aqueous sulphuric acid medium and mechanisms for oxidation and polymerization were proposed. Michaelis–Menten kinetics were evident from the rates of oxidation with protonation of oxime being the noncompetitive complexation. A mechanism involving monomer in the initiating radical production step and mutual termination of growing radicals was proposed to account for the fractional orders in the initiator concentration and the monomer exponents higher than unity.
Molten bisphenol‐A polycarbonate‐poly(ethylene terephthalate) blends. I. Identification of the reactions
Authors: Godard P. , Dekoninck J. M. , Devlesaver V. , Devaux J. 
Published: April 2003

AbstractThis paper is devoted to the study of the reactions taking place in molten bisphenol‐A polycarbonate‐poly(ethylene terephthalate) mixtures. The analysis of the reaction products by infrared, proton and nuclear magnetic resonance spectroscopy, and by thermogravimetric analysis shows that the main reaction is an exchange reaction identical to that occurring in bisphenol‐A polycarbonate‐poly(butylene terephthalate) mixtures. However, some other reactions consecutive to this exchange reaction also take place, probably resulting from the instability of the ethylene carbonates produced by transesterification.
Synthesis and characterization of uracil base grafted polyacrylamides as polynucleotide analogs
Authors: Overberger C. G. , Ferng W. B. 
Published: April 2003

AbstractIn conjunction with the previous studies of the adenine base grafted polyacrylamides, the uracil base grafted polyacrylamides and their monomer model compounds were prepared. In this case, however, an amine bond instead of an amide bond was used to attach the pendants onto the amino active site. A wider range of grafting efficiency (45–90%) and a smaller hypochromic effect were observed. This increase in grafting efficiency is responsible for the observed increase in percent hypochromicity. The reactivity ratios of the monomer model compounds with complementary bases, e.g., uracil and adenine, were estimated from a Finemann–Ross plot. Continuous mixing experiments involving the synthetic polyacrylamides with complementary bases suggested that polymer–polymer mixtures form base‐paired complexes that stabilize the stacked conformation only in neutral aqueous solution. Electrostatic repulsion prèvented such stability in acidic or alkaline aqueous solution. The collective information from NMR, UV, and CD spectra suggested that uracil based grafted poly(2‐amino‐2‐methylpropyl)acrylamide (PDMPA) and poly(2‐amino‐2‐methylbutyl)acrylamide (PDMBA) exist in limited ordered conformation.
Kinetics and mechanism of polymerization of acrylonitrile by peroxomonosulphate
Authors: Manivannan Gurusamy , Maruthamuthu Pichai 
Published: April 2003

AbstractThe kinetics of polymerization of acrylonitrile initiated by peroxomonosulphate (PMS) has been carried out in the temperature range 45–60°C at constant ionic strength of 0.50 mol dm−3 under deaerated conditions. The rate of polymerization Rp has been investigated at various concentrations of monomer and initiator. The effects of [monomer], [initiator], [H+], ionic strength, temperature, and reducing agents (organic and inorganic substrates) on the rate of polymerization have been observed. Activation energy was found to be 15.2 kcal mol−1.
Vapor synthesis of high‐activity catalysts for olefin polymerization
Authors: Ittel Steven D. , Mulhaupt Rolf , Klabunde Ulrich 
Published: April 2003

AbstractVaporization of MgCl2 and other metal halides results in monomeric gas‐phase species. Cocondensation of these species with organic diluents such as heptane yields highly activated solids which are precursors to MgCl2 supported “high‐mileage” catalysts for olefin polymerization. These catalysts, prepared by treatment with TiCl4 followed by standard activation with aluminum alkyls display high activity for ethylene and propylene polymerization. MgCl2 can also be evaporated into neat TiCl4 to give a related catalyst. The concentration of MgCl2 in the diluent affects catalyst properties as does the nature of the diluent. TiCl3, 3TiCl3 · AlCl3, VCl3 and other metal halides are subject to similar activation.
Association of copolymers of methacrylic acid and 4‐vinylpyridine in comparison with an intermacromolecular complex of poly(methacrylic acid) with poly(4‐vinylpyridine)
Authors: Abe Koji , Senoh Saburo 
Published: April 2003

AbstractSolution properties of copolymers [C(MA‐Py)x] of methacrylic acid and 4‐vinylpyridine and intermacromolecular complexes of poly(methacrylic acid) (PMAA) and poly(4‐vinylpyridine) (PVP) in the presence or absence of a proton‐accepting water‐soluble polymer such as poly(ethylene glycol) (PEG) in water/methanol mixed solvent are studied by potentiometric titration, turbidity and viscosity methods. These copolymers behave like polyampholytes and their solubilities are strongly dependent with pH changes. The pH regions where they are precipitated around their isoelectric points are narrower than those of the intermacromolecular complex of PMAA with PVP. The polyampholyte can form an intermacromolecular complex with PEG in acidic solution but this complex is soluble in the medium.
Hydrolytic polycondensation of alkoxysilanes and modification of polymerization reactions
Authors: Yoldas Bulent E. 
Published: April 2003

AbstractPolymers having oxide network chains are produced by hydrolytic polycondensation of metal alkoxides and alkoxysilanes. Molecular morphology and molecular size distribution of these inorganic polymers are strongly affected by certain nonchemical parameters. Included among these parameters is the molecular separation of interacting species during the polymerization. There is strong evidence that the molecular size expansion occurs by two distinct processes: initially by a gradual “growth” process, and later by “recombination” of high‐molecular weight species. The later process often leads to a bi‐modal molecular size distribution. The concentration of water‐rich siloxane solutions leads to significant molecular size expansion by further oxide network formation. No similar polymer size growth occurs during the concentration of alcohol based solutions. This difference in the polymeric activities can be related to the difference in the terminal bond under the two different conditions.
Synthesis of copolyamides based on ε‐caprolactam and AH salt in the presence of cationic resin
Authors: Nevrekar Nitin B. , Joshi K. A. 
Published: April 2003

AbstractCopolyamides based on ε‐caprolactam and AH salt were prepared by copolymerization of various combinations of ε‐caprolactam and AH salt in the presence of a cationic resin. In terms of adhesivity towards metals they have proved their superiority over nylon 6, nylon 6, 6, and the copolyamides of ε‐caprolactam and AH salt, prepared in presence of water. Adhesive property of the copolyamide was found to be increased with increasing proportion of AH salt in the combinations. ε‐Caprolactam (1 part) and AH salt (5 parts) in presence of a cationic resin (0.55%) were copolymerized to give a best performing copolyamide: yield 93%, mp 232°C, relative viscosity 2.42, and shear tensile strength 620 kg/in.2
Polymerization of surface‐active monomers. II. Polymerization of quarternary alkyl salts of dimethylaminoethyl methacrylate with a different alkyl chain length
Authors: Nagai Katsutoshi , Ohishi Yoshiyuki 
Published: April 2003

AbstractThe cationic monomers (CNBr), obtained by quarternization of dimethylaminoethyl methacrylate with n‐alkyl bromide containing varying carbon number (N = 4, 8, 12, 14, and 16) were polymerized with radical initiators in water and various organic solvents. The degree of polymerization of the resulting polymers was determined by GPC measurements on poly(methyl methacrylate) samples derived from them. The rate of polymerization of the micelle‐forming monomers (N = 8, 12, 14, and 16) in water increases with increasing a chain length of alkyl group, whereas it is little dependent on N in isotropic solution in dimethylformamide. The data on the degree of polymerization for the polymers of C4Br, C8Br, and C12Br show that the polymerization of C12Br with azo initiators in water and benzene gives polymers with a very high degree of polymerization. The results obtained here suggest that highly developed or relatively rigid, aggregated structures of monomers in solution are responsible for the formation of the polymers with a very high degree of polymerization, in addition to an enhanced rate of polymerization. Also considered are the relation of the molecular weight of poly(C12Br) to the viscosity data in chloroform and methanol.
Synthesis of poly(styrene‐tetrahydrofuran‐2‐methyl‐2‐oxazoline) triblock and graft copolymers
Authors: Ishizu Koji , Fukutomi Takashi 
Published: April 2003

AbstractPoly[styrene (ST)‐tetrahydrofuran (THF)‐2‐methyl‐2‐oxazoline(MeOz)] triblock and graft copolymers were prepared by ionic polymerizations. Poly(ST‐THF) graft copolymers were synthesized by coupling of ST‐4‐vinylpyridine (4VP) copolymer with a large excess of PTHF dication. The ion coupling of PST dianion with PTHF dication was accompanied by the side reaction (abstraction of α proton of oxonium ion). After tosylation of terminal hydroxyl groups of PTHF blocks, cationic copolymerizations of MeOz with poly(ST‐THF) block and graft copolymers were carried out, and characteristics of produced copolymers were investigated in some detail.
Elementary reactions of the emulsions polymerization of styrene with the localization of radical formation acts at the interface
Authors: Ivanchev S. S. , Pavljuchenko V. N. , Byrdina N. A. 
Published: April 2003

AbstractThe localization of radical formation acts at the interface achieved by the application of specially prepared surfactant initiators, fixation of initiating sites on the surface of seed latex particles by covalent bonds, or by redox initiating systems were experimentally studies. It is ascertained that the fixation of the initiator of polymerization at the interface of the emulsion system brings about a change of the kinetic parameters of its decomposition—an increase in the decomposition rate and decrease in the initiation efficiency. The experiments (measurements of chain propagation rate) demonstrated that the nature of emulsifying agent and initiator has no effect on the chain propagation acts. The kinetics of the chain termination depends on the properties of the emulsion system that is revealed in the dependence of chain termination constants on the type of initiator and the diameter of latex particles. These effects are supposed to be explained by influence of the colloid and chemical parameters of the reaction system on the conformation entropy of the growing macroradicals; and the low values of the chain termination constants (102–104 L mol−1 s−1) are due to the higher activation energy of chain termination for the emulsion polymerization.
Polymer‐supported bases. 5. Acetylation of linalool with acetic anhydride using dialkylaminopyridines attached by spacer chains to polystyrene resins
Authors: Tomoi Masao , Goto Makio , Kakiuchi Hiroshi 
Published: April 2003

AbstractThe acetylation of linalool with acetic anhydride was carried out in the presence of polystyrene‐bound aminopyridines and triethylamine. The catalytic activity of the immobilized aminopyridines increased with decreasing percentage of ring substitution and with increasing spacer‐chain length. The increased activity is attributed to an increase in the amount of aminopyridine units complexed with acetic anhydride. The acetylation could be successfully conducted by use of a mixture of the immobilized aminopyridines and polymer‐supported benzyldiethylamine, which effectively trapped acetic acid formed in the reaction system.
Soluble alkyl substituted polygermanes: Thermochromic behavior
Authors: Miller R. D. , Sooriyakumaran R. 
Published: April 2003

AbstractWe have prepared a number of high molecular weight, soluble, symmetrical dialkyl substituted germanium homopolymers and germanium‐silicon copolymers. In solution, the absorption of the homopolymers was ∼ 20 nm red shifted from the crossponding silicon derivatives. This was somewhat unexpected based on theoretical predictions and has been rationalized on the basis of conformational arguments. In the solid state, samples of poly(di‐n‐hexylgermane) and poly(di‐n‐octylgermane) are strongly thermochromic. The effect is attributed to the conformational locking of the backbone which is caused by the crystallization of the side groups. In this regard, the germanium derivatives behave similarly to the corresponding silicon polymers, and the convergence of the long wavelength absorptions for both types of polymers is consistent with theoretical predictions. The germanium‐silicon copolymers are also strongly thermochromic, but the long wavelength absorption is somewhat blue shifted (8 nm) from the respective homopolymers. As expected, the new germanium homo and copolymers are quite sensitive to light and readily undergo chain scission to produce lower molecular weight materials.
Thermal decomposition behavior of mono‐aminimides and their application to polymerization of epoxide
Authors: Inubushi Shinzo , Ikeda Tomiki , Tazuke Shigeo , Satoh Tasuku 
Published: April 2003

AbstractMono‐aminimide compounds [N,N‐dimethyl‐N‐(2‐hydroxypropyl)‐amine‐N′‐propionimide (1), trimethylamine valerimide (2), and trimethylamine benzimide (3)] were found to exhibit different thermal decomposition behaviors and polymerization efficiencies for an epoxide (phenyl glycidyl ether, PGE). The thermal decomposition rate of aminimides at 150°C decreased in the order 1 > 2 > 3. It seemed that hydrogen bonding enchanced the decomposition rate, and the resonance effect induced by the phenyl group suppressed the decomposition. 1 was thermolyzed to give isocyanate and tertiary aminoalcohol, which subsequently reacted with each other to give isocyanate and tertiary aminoalcohol, which subsequently reacted with each other to give urethane. When 2 was heatted, the isocyanurate generated from 2 remained intact. On heating of 3, we observed the formation of triphenyl isocyanurate. PGE reacted with those aminimides and gave different products depending on their thermolyzed products. Equimolar mixtures of isocyanate, tertiary amine, PGE were used in the model reactions, and the thermal reaction between the expected decompostion products of aminimides was investigated in the presence and absence of PGE. The rate of PGE consumption was in the order PGE + 2 > PGE + 1 > PGE + 3. It is clear that the formation of urethanes and oxazolidone derivatives affects the polymerization process.
Effects of linking groups in fluorinated aromatic polyamides
Authors: Whang W. T. , Pearce E. M. 
Published: April 2003

AbstractBased on dynamic thermogravimetric analysis (TGA) of fluorinated aromatic polyamides, we found that substituting terephthaloyl units for isophthaloyl units usually increased the thermal stability of the polymers. In contrast, the first steps of thermal degradation of poly(5,5′‐sulfonyl‐2,2′‐difluoro‐diphenyl terephthalamide) (2,2′‐DIF‐PSDPT) and poly(5,5′‐sulfonyl‐2,2′‐difluorodphenyl isophthalamide)(2,2′‐DIF‐PSDPI) followed almost the same curve. This was attributed to the relative flexibility of the SO2 group, and also to the activating effect on the dehydrofluorination reaction, which was believed to be the first step of the degradation of the ortho‐fluorinated aromatic polyamides, , resulting in the formation of benzoxazole groups, , on the polymer backbone. With fluorinated aromatic polyamides having ortho fluorine to the amide nitrogen, the electron releasing CH2 group deactivated the nucleophilic substitution of the dehydrofluorination reaction and the electron withdrawing group SO2 activated the reaction, so that the onset degradation temperatures of the fluorinated aromatic units R in followed the order:
Photodegradation of poly(vinylacetophenone). II. Short‐wave photolysis
Authors: Weir N. A. , Arct J. 
Published: April 2003

AbstractThe photodegradation of films (2 × 10−4 cm thick) of poly(vinyl‐acetophenone) [poly(4‐acetylstyrene)] exposed to 254 nm radiation under high vacuum at 25 ± 1°C was studied. The principal gaseous product was H2, but CH4, C2H6, and smaller amounts of acetaldehyde and CO were also formed. The photochemistry more closely resembles that of other substituted styrene polymers than that occuring on the long wave (λ > 300 nm) irradiation of the polymer in that the principal initial processes involve fissions of bonds in the β‐position to the phenyl chromophores. Studies of a deuterated analogue (D3 acetyl) indicate that H‐abstractions occur from the polymer and also that fission of CH bonds in the acetyl group does not occur. The polymer undergoes rapid cross linking. Mechanisms of the various primary and secondary processes are discussed.
Crosslinking of polyaromatic ether‐ketones with biphenylene derivatives
Authors: Ogawa Takeshi , Marvel C. S. 
Published: April 2003

AbstractPolyaromatic ether‐ketones prepared from isophthaloyl dichloride, diphenyl ether, and various amounts of biphenylene and its derivative, were compressed to films under various conditions, and their crosslinking behaviors were studied. Although strong and flexible films could be obtained from low melting crosslinkable polymers, the low molecular weight polymers, which melt below 300°C, decompose at the biphenylene ring opening temperature of over 290°C, giving films full of gas bubbles. The addition of metal complexes to decrease the biphenylene ring opening temperature did not improve the film quality, although gas bubbles could be avoided. The strong and flexible films were amorphous, and the brittle films were mixtures of crystalline and amorphous polymers.
Polymerization of vinyl chloride in the presence of modified Ziegler–Natta catalysts comprising long chain organoaluminum compounds
Authors: Florjanczyk Zbigniew , Kuran Witold , Sitkowska Jadwiga , Ziółkowski Andrzej 
Published: April 2003

AbstractPolymerization of vinyl chloride in the presence of systems containing a transition metal compound/Lewis base and an organoaluminum compound of a different length of carbon chain have been carried out. The influence of the structure and the concentrations of particular components on the polymerization yield and molecular weight of the products has been determined. The polymerization of vinyl chloride proceeds according to the free radical mechanism, and the effectiveness of such types of initiators decreases with an increase in the length of the substituent chain in the organoaluminum chain. When using ethyl derivatives, the maximum degree of vinyl chloride conversion is about 75%, and for polystyryl or polyisoprenylaluminum of an average polymerization degree of 50–100, the conversion did not exceed 0.5%. The maximum polymerization degree of vinyl chloride in block copolymers containing polyisoprenyl or polystyryl units was 90–300.
Poly(α‐methylstyrene‐b‐styrene) by a cationic mechanism
Authors: De Souza Gomes Ailton , Soares Bluma Guenther 
Published: April 2003

AbstractBlock copolymers of styrene and α‐methylstyrene were obtained by a cationic mechanism involving a single‐step addition in the m‐chloroperbenzoic acid/liquid sulfur dioxide system. This result was possible because of the difference in the reactivity of these monomers in the temperatures of −40°C, −60°C, and −78°C. Under these temperature conditions α‐methylstyrene is more reactive than styrene. The composition of the block copolymers was determined by NMR and TGA analysis in fractionated samples.