bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and some properties of 2,2,6,6‐tetrahydryl‐F‐heptanedioic acid and its polyester with 1,1,5,5‐tetrahydryl‐F‐1,5‐pentanediol
Authors: Johncock P. , Barnett Susan P. , Rickard Patricia A. 
Published: April 2003

Abstract2,2,6,6,‐Tetrahydryl‐F‐heptanedioic acid was prepared by hydrolysis of 1,7‐diethoxy‐2,6‐dihydryl‐F‐1,6‐heptadiene, which was obtained by a copper‐induced coupling reaction between 1,3‐di‐iodo‐F‐propane and 1‐ethoxy‐1‐fluoro‐2‐iodethylene. This olefin is obtained almost exclusively as the less thermodynamically stable isomer in the reaction between 1,1‐difluoro‐2‐iodoethylene and soidum ethoxide. Synthesis of the acid via 2,2,6,6,‐tetrahydryl‐F‐heptanedial was unsuccessful, since the latter readily underwent cyclopolymerization. The acid has pK = 2.38 and pK = 3.35, and slowly liberates fluoride ion in aqueous solution. The polyester obtained with 1,1,5,5,‐tetrahydryl‐F‐1,5‐pentanediol is highly crystalline with a mp of 79°C and a history‐dependent Tg of 6 to 75°C. Polymer with a high amorphous content had a reproducible Tg of −35°C. The polyester has good solvent resistance to hydrocarbons, and comparable thermal stability to the corresponding polyester prepared from isophthalic acid.
Synthesis of acryloyl‐type polymer fixing 5‐fluorouracil residues through D‐glucofuranoses and its antitumor activity
Authors: Ouchi Tatsuro , Fujie Hirotoshi , Jokei Satoshi , Sakamoto Yoshiomi , Chikashita Hidenori , Inoi Takeshi , Vogl Otto 
Published: April 2003

AbstractAcryloyl‐type polymer fixing 1‐β‐carbonylethyl‐5‐fluorouracil residues through D‐glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water‐soluble objective polymer, the copolymerization of the acryloyl‐type monomer with acrylamide was carried out. The extent of release of 5‐FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water‐insoluble homopolymer and water‐soluble copolymer obtained were tested in vivo.
Formation of formal compounds in reaction of dimethyl phenols with formaldehyde
Authors: Yoshimura Yukio 
Published: April 2003

AbstractFormaldehyde was reacted with both 2,4‐dimethylphenol(2,4‐xyenol) and 2,6‐dimethylphenol(2,6‐xylenol), which are model compounds of monofunctional phenols, and the reaction products were subjected to HLC analysis to elucidate details of the formation process and bonding manner of a formal group, which can greatly affect the performance of phenol–formaldehyde resins. As a result, formal compounds of dimethylphenols were successfully separated by HLC. It was further found, as a result of tracing the reactions by HLC, that the formation of a formal group occurs at either position of the ortho and para positions, and that methylol compounds were formed following formation of the formal compounds. Furthermore, as a result of NMR analysis as well as consideration of solvation on the basis of the relative elution volumes of the nonacetylated and acetylated reaction products it was found that the formal group was added to the phenol nuclei.
An ESR study of radiation damage of bisphenol‐A‐based epoxy resin at low temperature: Selective hydrogen addition to benzene‐ring‐forming cyclohexadienyl‐type radical
Authors: Eda Bunzo , Iwasaki Machio 
Published: April 2003

AbstractIn the γ‐irradiated aromatic epoxy resin, diglycidylether of bisphenol A cured with diaminodiphenylmethane, the cyclohexadienyl‐type radical is produced as one of the main radical species. Although both the resin and the hardener contain benzene rings, it is concluded that the cyclohexadienyl‐type radical is formed by selective addition of the OH hydrogen to the benzene ring on the resin side. The selectivity is accounted for in terms of electron capture by the benzene ring followed by proton transfer from the OH group which is located in front of the benzene ring. This reaction scheme is further supported by the effect of the addition of an electron scavenger on the radical yield as well as by the photobleaching behavior of the radicals involved.
BDMA‐catalyzed DDA‐epoxy resin system: Temperature and composition effects on curing mechanism
Authors: Lin Y. G. , Sautereau H. , Pascault J. P. 
Published: April 2003

AbstractDSC and IR data on benzyldimethylamine‐catalyzed dicyandiamide‐DGEBA prepolymer system have been utilized to investigate the influences of temperature and composition on the curing mechanism. Etherification as a competitive reaction is favored at lower temperature. On the other hand, the reaction pathway of dicyandiamide (DDA) varies with temperature, especially at the first stage of reaction. At 100°C, the reaction of DDA is shown to be essentially the substitution of the hydrogen atoms by ring‐opening of epoxy groups, giving rise to N‐alkyl cyanoguanidine. But at 140°C or 160°C, the initial reaction of DDA involves a transformation of nitrile groups to imine groups. A greater amount of BDMA and a higher amine‐to‐epoxy ratio favor the etherification. The glass transition temperature Tg is a complex function of these different mechanisms; higher Tg could be reached with a amino‐to‐epoxy ratio equal to 0.6 and after a curing cycle including a precure at 100°C.
Radical addition to 2‐isopropenyl‐5‐butoxyoxazole
Authors: Drapier J. , Parla D. , Moniotte Ph. , Warin R. , Hubert A. J. , Teyssie Ph. 
Published: April 2003

AbstractThe preparation and the spectroscopic analysis of a dimeric adduct (V) obtained from 2‐isopropenyl‐5‐butoxyoxazole (III) and α,α‐azobis‐isobutyronitrile (AIBN) (IV) are reported. It is noteworthy that (III) inhibits completely the homopolymerization of styrene. This is in strong opposition to the facile homopolymerization and copolymerization of 2‐isopropenyl‐4,5‐dimethyloxazole with styrene. The smooth formation of (V) is also in sharp contrast to the lack of reactivity of (III) towards cationic initiators.
Monomer chain transfer in the copolymerization of styrene and butyl acrylate
Authors: Devon Michael J. , Rudin Alfred 
Published: April 2003

AbstractFree radical chain transfer constants have been measured by copolymerizing styrene and butyl acrylate in emulsion at 60°C. Some improvements to this experimental technique are reported and estimates are given of the sensitivity of the calculated values to experimental uncertainties. Monomer chain transfer constants were found to be 1.2 × 10−4 (styrene) and 2.5 × 10−4 (butyl acrylate). The sum of the cross‐transfer constants is 2.7 × 10−4. The activation energy for chain transfer to styrene monomer is found to be 24 Kcal/mol in the 44°–60°C range.
A model study for coatings containing hexamethoxymethylmelamine
Authors: Meijer E. W. 
Published: April 2003

AbstractUsing a model reaction we have studied the crosslinking chemistry of hydroxy‐functional polymers and hexamethoxymethylmelamine. The transetherification of optically active monofunctional alcohols and hexamethoxymethylmelamine was monitored with polarimetry and 1H‐NMR. The reaction rate constants for both the forward (k1) and the backward (k−1) reaction of the sulphonic‐acid‐catalyzed alcoholysis were determined. Primary and secondary alcohols showed the same reaction rate and activation energy (Ea = 96 kJ/mol) for the forward reaction. However, the backward reaction in the equilibrium is considerably slower for primary alcohols than for secondary alcohols, with activation energies of Ea = 96 and 79 kJ/mol, respectively. When amine salts of sulphonic acids are used as catalysts, the Ea is increased from 97 to 116 kJ/mol in the case of primary alcohols. In concentrated aprotic solutions the reaction order in acid is 2.5. The same order in acid is found for the alcoholysis of acetaldehyde diethyl acetal. All the results strongly support the statement that the crosslinking reaction proceeds by an Sn‐1 mechanism. The results of this model study are compared with results obtained in network‐forming reactions. The important role of the evaporation of the condensation product methanol is discussed.
Thermotropic copolyesters containing the 1,4‐cyclohexylenedimethylene spacer
Authors: Onwumere Fidelis C. , Polk Malcolm B. 
Published: April 2003

AbstractPoly[oxy(2‐methyl‐1,4‐phenylene)oxyterephthaloyl‐co‐oxy(2‐methyl‐1,4‐phenylene)oxy‐1,4‐cyclohexanediacetoyl] (I), poly[oxy(2‐chloro‐1,4‐phenylene)oxyterephthaloyl‐co‐oxymethylene‐1,4‐cyclohexylenemethyleneoxyterephthaloyl] (II), and poly[oxy(2‐methyl‐1,4‐phenylene)oxyterephthaloyl‐co‐oxymethylene‐1,4‐cyclohexylenemethyleneoxyterephthaloyl] (III) were synthesized and shown to form birefringent fluid states in the melt.
Living polymerization of isobutyl vinyl ether by HI/I2 initiator in polar solvents
Authors: Enoki Takashi , Sawamoto Mitsuo , Higashimura Toshinobu 
Published: April 2003

AbstractThis study has shown a nearly perfect living polymerization of isobutyl vinyl ether (IBVE) to proceed not only in nonpolar media (e.g., n‐hexane) but in relatively polar CH2Cl2 solvent, provided that the HI concentration is sufficiently high. The produced polymers had a nearly monodisperse molecular weight distribution (Mw/Mn ≤ 1.1); the number‐average molecular weight (Mn) increased in direct proportion to IBVE conversion and its increase continued on the addition of a fresh feed of the monomer at the end of the polymerization. The use of a more polar medium (PhNO2/CH2Cl2) or a lower HI concentration leads to chain transfer reactions, by promoting the ionic dissociation of the “nondissociated” living propagating species. The successful living polymerization by HI/I2 in CH2Cl2 indicates a very strong interaction between the iodide anion and the growing end.
Poly(enamine‐ketones) from aromatic diacetylenic diketones and aromatic diamines
Authors: Sinsky M. S. , Bass R. G. , Connell J. W. , Hergenrother P. M. 
Published: April 2003

AbstractNovel poly(enamine‐ketones) were prepared with inherent viscosities as high as 1.99 dL/g using the Michael‐type addition of various diamines to 1,1′‐(1,3 or 1,4‐phenylene)bis(3‐phenyl‐2‐propyn‐1‐one) in m‐cresol at 60–130°C. Tough, clear, amber films with tensile strengths of 12, 400 psi and tensile moduli of 397, 000 psi were cast from solutions of the polymers in chloroform. The polymers exhibited Tgs as high as 235°C and weight losses of 14% after aging at 232°C in circulating air for 60 h. The synthesis and characterization of several poly(enamine‐ketones) are discussed.
Crosslinked polydiacetylene and its two‐ and three‐component interpenetrating polymer networks (IPNs)
Authors: Ika Prasad V. S. , Frisch Harry L. , Walters Gary R. , Painter Paul C. , Frisch Kurt C. 
Published: April 2003

AbstractThe synthesis of crosslinked polydiacetylene [poly4ECMU (a polydiacetylene with ethoxy carbonyl methylene urethane substitution): where R = (CH2)4OCONHCH2COOCH2CH3] was carried out utilizing its polar and flexible substituent groups. Polydiacetylene was crosslinked by the formation of allophanate linkages utilizing urethane groups in the substituent groups of the polydiacetylene. Two‐component IPNs of polydiacetylene [poly4BCMU (a polydiacetylene with butoxy carbonyl methylene urethane substitution): where R = (CH2)4OCONHCH2COO(CH2)3CH3] and an epoxy resin (diglycidyl ether of Bisphenol A) were synthesized. Two‐component IPNs of poly4ECMU with the above epoxy resin were also synthesized. For the first time, two‐component stiff‐backbone IPNs of two different kinds of polydiacetylene (poly4BCMU and polyECMU) and a three‐component IPN of poly4BCMU, poly4ECMU, and the epoxy resin were synthesized. IPNs with fewer allophanate linkages were also made in order to examine morphological differences between them. The glass transition behavior of these networks was studied using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) by means of a Rheovibron.
Polymerization using palladium (II) salts: Homopolymers and copolymers from phenylethynyl compounds and aromatic bromides
Authors: Trumbo D. L. , Marvel C. S. 
Published: April 2003

AbstractLow‐molecular‐weight homopolymers of m‐bromophenylacetylene, as well as copolymers and networks of select di‐ and triethynyl benzenes with di‐ and tribromobenzenes, have been synthesized via a coupling reaction utilizing a palladium (II) salt, triphenylphosphine, cuprous iodide catalyst system.
Products characterization of tung oil–phenol reactions based on analysis of a model reaction
Authors: Yoshimura Yukio , Nomoto Masahiro 
Published: April 2003

AbstractA method of determining the molecular species composition distributions of products obtained by reaction of tung oil with various phenols in the presence of acid catalyst has been studied. Methyl α‐eleostearate was used as a model substance in place of tung oil. The product composition analysis of methyl α‐eleostearate reactions with phenols was done by HLC. From these results, the molecular weight distributions and molecular species composition distributions of the reaction products were calculated according to a statistical procedure. Good agreement was found between the calculated and experimental molecular weight distribution, which enabled prediction of the molecular species composition distribution.
Studies on some radical transfer reactions by entrapping the radicals as polymer end groups. I. Reaction of hydroxyl radicals with amines
Authors: Pramanick Dinabandhu , Bhattacharyya Ramanath 
Published: April 2003

AbstractThe reaction of OH radicals with a number of amines has been studied by entrapping the resultant radicals as polymer end groups which have been detected and estimated by the sensitive dye partition technique. Expressions have been developed relating the average amounts of end groups per polymer molecule to the rate constant of the radical transfer reaction, the rate constants determined for reaction with n‐butyl, n‐hexyl, and n‐octyl amine being 1.00 × 1010, 1.31 × 1010, and 1.46 × 1010 mol−1 L s−1, respectively, at 25°C. The order of reactivity for amines of different classes has been found to be as primary < secondary > tertiary, the rate constants for reaction with n‐butyl, dibutyl, and tributyl amine being 1.00 × 1010, 1.81 × 1010, and 1.67 × 1010 mol−1 L s−1, respectively, at 25°C. The change in the reactivity of the amine with chain length and amine class has been explained by activation and deactivation of the CH2 group from which H abstraction by OH radicals occurs, respectively, by the alkyl group and by the protonated amino nitrogen under the acidic condition of the medium. Between pH 1.00 and 2.17, the rate of the reaction with n‐butyl amine remains practically unchanged, but from pH 2.20 to 2.72 the rate constant increases with increasing pH, indicating that deprotonation of the positively charged nitrogen starts at about pH 2.20. The method is simple and accurate and can be applied to detect and estimate very reactive radicals.
The curing of epoxy resins with aminophenoxycyclotriphosphazenes
Authors: Kumar Devendra , Fohlen George M. , Parker John A. 
Published: April 2003

AbstractAminophenoxycyclotriphosphazenes have been used as curing agents for epoxy resins. The thermal curing was performed in stages at 120–125 and 175–180°C followed by postcuring at 225°C to give tough brown polymers. The thermal curing reaction was monitored using FTIR and differential scanning calorimetry. Thermogravimetric analysis of the cured resins has shown thermal stability up to 350–340°C. The char yield obtained in nitrogen at 800°C was about 55–42% and in air at 700°C was about 40–32%. Graphite cloth laminates were prepared. The mechanical properties evaluated were found superior to those of commonly used epoxy resin systems. These resins are useful for making fire‐ and heat‐resistant composites, laminates, molded parts, and adhesives.
Recovery of thick shear bands in atactic polystyrene
Authors: Kung Teh‐Ming , Li J. C. M. 
Published: April 2003

AbstractThe DSC thermograms of the shear band material cut out by a diamond saw to include some undeformed material revealed two Tg's clearly separated by about 10°C. The first Tg was at the same temperature as the Tg of the undeformed material. The second Tg, which was at a higher temperature than the first Tg, appeared shortly after the shear strain recovery during the heating of the shear band material in the DSC. When the shear strain in the shear band was partially reversed by mechanical means before taking the DSC thermogram, the ΔT between the two Tg's decreased and when the shear strain was mechanically reversed to almost zero, the second Tg disappeared. The stored energy of shear band material was found to be similar to that of the bulk compressed material for large strains. Dimensional recovery during heating of specimens with thick and fine bands was similar, both taking place above Tg.
Displacement polymerization. III. Synthesis and characterization of polyazoxyarylethers
Authors: Mandal Braja K. , Maiti Sukumar 
Published: April 2003

AbstractA new class of polyazoxyarylethers was prepared by nucleophilic displacement polymerization using an activated dichlorocompound and a bisphenol dianion in anhydrous aprotic solvent. Model reactions were studied with 3,3′‐ and 4,4′‐dichloroazoxybenzene and various phenol and thiophenol salts to find out the reaction conditions for polycondensation. IR, 1H NMR, and elemental analyses were used to establish the structure of the model compounds and the polymers. Thermal analysis indicated that the oxy derivative is less prone to thermo‐oxidative degradation than the corresponding thio derivative of polyazoxyarylether. The polymers are crystalline and soluble in halogenated hydrocarbons and polar solvents.
Radiation‐induced graft copolymerization of N‐vinyl carbazole and methyl methacrylate onto cellulose acetate film
Authors: Bhattacharyya S. N. , Maldas D. , Pandey V. K. 
Published: April 2003

AbstractN‐Vinyl carbazole methyl methacrylate, and the binary mixtures of these monomers were grafted onto cellulose acetate films by taking recourse to Co‐60 simultaneous irradiation grafting technique. The effect of various parameters (e.g., solvents, radiation dose, compositions of the monomers, and concentration of the monomers) on the extent of grafting in unitary and binary systems were studied. The optimum conditions for grafting were evaluated. The sensitizing effect of one monomer in the presence of other in the binary system was identified. The relative molecular reactivity and reactivity ratios were computed and these were used in explaining sensitization and the effect of monomer compositions on the extent of grafting in the binary system.
Novel polybenzoxazinones with tricyclic fused‐rings
Authors: Subramaniam Prema , Srinivasan Mahalingam 
Published: April 2003

AbstractA series of polybenzoxazinones containing phenoxathiin and phenoxaphosphine units were prepared from tricyclic diacid chlorides and 4,4′‐diaminobiphenyl‐3,3′‐dicarboxylic acid and 4,4′‐diamino‐3,3′‐diphenylmethane dicarboxylic acid. The low temperature solution polymerization technique afforded polyamic acid which subsequently underwent cyclization along the polymer chain in a solvent mixture of refluxing N,N′‐dimethylacetamide, acetic anhydride, and pyridine to give polybenzoxazinones in moderate yields. The polymers thus obtained had inherent viscosities in the range of 0.15–0.23 dL/g, were sparingly soluble in N‐methyl‐2‐pyrrolidone, and were found to be thermally more stable than the corresponding open‐chain polymer with diphenylether linkage.
Free‐radical polymerization of methyl methacrylate and p‐fluorostyrene in the presence of the Mn(acac)3–AlEt3 catalyst system
Authors: Kothandaraman H. , Palanivelu K. 
Published: April 2003

AbstractMethyl methacrylate and p‐fluorostyrene were polymerized with manganese (III) acetylacetonate–aluminum triethyl catalyst at 60°C in a benzene medium. Maximum activity was found at Al/Mn ratio of 4. Maximum percent conversion of polymer was obtained when the aging time of the catalyst was 10 min. The rate of polymerization was first order with respect to monomer. The rate of polymerization with respect to catalyst and cocatalyst were found to be 0.5 and 1.5, respectively. The overall energy of activation for the polymerization of methyl methacrylate and p‐fluorostyrene were found to be 52.6 and 57.0 kJ/mole, respectively. A free‐radical mechanism is postulated.
Investigation of polymer miscibility by spectroscopic methods V. Effect of molecular weight and block copolymerization of syndiotactic poly(methyl methacrylate) on its miscibility with poly(vinyl chloride)
Authors: Albert B. , Jerome R. , Teyssie Ph. , Baeyens‐Volant D. 
Published: April 2003

AbstractInvestigated by nonradiative energy transfer (NRET), the state of mixing of PVC and s.PMMA which is on the dimensional scale of a few nanometers is significantly affected by the chain length. When PVC is blended with s.PMMA of increasing molecular weight (MW), the longest chains of s.PMMA are likely to segregate from a homogeneous blend formed by PVC and low‐MW s.PMMA. The phase separation should therefore be of purely entropic origin and strongly dependent on both the relative percentage and the chain length of each component. These results are in qualitative agreement with conclusions previously drawn from DSC and transmission electron microscopy. NRET is a more powerful tool in probing heterogeneities compared to DSC and the thermally stimulated depolarization current method; it provides evidence against the previously suggested model of a 1:1 PVC/s.PMMA aggregate.
Influence of preferential solvation on the interpolymer complex formation between methacrylic acid–methacrylamide copolymer and poly(vinyl pyrrolidone)
Authors: Chatterjee S. K. , Malhotra A. , Yadav D. 
Published: April 2003

AbstractInterpolymer complex formation has been studied between methacrylic acid–methacrylamide copolymer and poly(vinyl pyrrolidone) in acetone–water mixtures of different compositions. At a specific composition of the solvent (e.g., 70% water + 30% acetone by volume), the intrinsic viscosity of the copolymer and the reduced viscosity of 1:1 interpolymer complex had minimum values. Preferential solvation coefficients (λ/C) have been calculated for the various compositions of the solvent mixtures. An excellent coincidence could be obtained between the maximum (λ/C) and the minimum in the viscosity of the polymer solutions. Interpretations have been sought in terms of conformational change of the copolymer at the specific composition of the solvent mixture.
Water‐soluble copolymers. XIII. Copolymers of acrylamide with sodium‐3‐acrylamido‐3‐methylbutanoate: Solution properties
Authors: McCormick C. L. , Blackmon K. P. , Elliott D. L. 
Published: April 2003

AbstractDilute solution properties of copolymers of acrylamide (AM) with sodium‐3‐acrylamido‐3‐methylbutanoate (NaAMB) of known molecular weight have been studied as a function of composition, temperature, time, pH, and added electrolytes. Phase separation and potentiometric studies have also been performed. The AM–NaAMB copolymers exhibit high solution viscosities, good salt tolerance, and moderate viscosity‐temperature coefficients. In addition, these copolymers exhibit no phase separation in the presence of divalent cations as is common with many such carboxylated polyelectrolytes. These properties are due to favorable conformations in solution resulting from microstructure and hydrogen bonding effects.