bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear polythioesters. VII. Products of interfacial polycondensation of 1,4‐di(mercaptomethyl)‐2,3,5,6‐tetramethylbenzene with some aliphatic acid dichlorides
Authors: Podkoscielny Wawrzyniec , Kowalewska Wanda
Published: April 2003

Several polythioesters by interfacial polycondensation of 1,4‐di(mercaptomethyl)‐2,3,5,6‐tetramethylbenzene with oxalyl, succinyl, adipoyl, suberoyl, and sebacoyl chlorides were obtained. To determine the optimal conditions for interfacial polycondensation, the influence of the following factors on yield and value of reduced viscosity were studied: type of organic phase, concentration of hydrogen chloride acceptor, the quantitative ratio of aqueous to organic phase, molar ratio of reagents; temperature of reaction, rate of acid chloride addition, and contribution of catalyst. Thorough studies were carried out only for polycondensation of the dithiol with adipoyl and sebacoyl chlorides. The structure of all polythioesters obtained under the model conditions was determined by elementary analysis and infrared spectra. Initial decomposition temperature, mass loss in percentage at the same temperature, maximum rate of decomposition, and mass loss percentage at 100–400°C were defined by thermogravimetric analyses. Chemical resistance of the polythioesters was determined by treatment with some organic solvents, mineral acids (concentrated and 10%), and sodium hydroxide (10 and 50%). Some mechanical and electrical properties of the polythioesters obtained from dithiol and adipoyl and sebacoyl chlorides were determined. The molecular weight was not measured because of the low solubility of the polythioesters.
Synthesis and conformation of asymmetric rigid polyamides
Authors: Overberger C. G. , Wang David Wei
Published: April 2003

Asymmetric polyamides from the reaction of either optically active trans‐1,2‐cyclopropanedicarboxylic acid (C3) or trans‐1,2‐cyclohexanedicarboxylic acid (C6) with 2,7‐diazaspiro[4,4]nonane(DSN) were synthesized. The possible conformations of these polymers and their model compounds in 2,2,2‐trifluoroethanol (TFE), water, methanesulfonic acid (MSA), and sulfuric acid were examined by circular dichroism (CD), NMR, viscosity, and dipole moment measurements. The racemic polyamides (±)C3·(±)DSN and (±)C6·(±)DSN exist in extended forms. No intrinsic viscosity changes were observed for these two polymers in TFE and MSA. Certain viscosity and spectral changes have been observed for the optically active polyamides, although no specific ordered conformations can be assigned. The optically active diacid units incorporated into the polymer give a conformation unique from the totally extended chain. CD studies seem to evidence some conformational differences among the polyamide derived from (+)C6 diacid and the optically active DSN. By changing the solvent from TFE to MSA a blue shift of the trough was observed for (+)C6·(±)DSN, a red shift for (+)C6·(−)DSN, and an inversion of the CD spectrum for (+)C6·(+)DSN polyamides. The results of the work with (+)C6·(−)DSN in dilute acid solution suggest that the rotation around the C–N bond is a relatively low‐energy process. The spectral and intrinsic viscosity data are consistent with this suggestion. No drastic spectral changes have been observed for the C3·DSN polyamides by changing the solvent from TFE to MSA. The amide group in the C3·DSN polyamide and the corresponding model compound prefer a similar conformation with the carbonyl group bisecting the cyclopropane ring. The C3·DSN polyamide seems to exist in an extended form.
Interaction of α‐poly‐L‐lysine and ε‐poly‐L‐lysine with methyl orange and its homologs in aqueous solution: Results from dialysis and spectroscopic measurements
Authors: Takagishi Toru , Ueno Toshihiko , Kuroki Nobuhiko , Shima Shoji , Sakai Heiichi
Published: April 2003

The interaction of α‐poly‐L‐lysine and ε‐poly‐L‐lysine with methyl and ethyl orange was studied by equilibrium dialysis and spectroscopic methods. The results of the dialysis measurements indicated that the extent of binding by ε‐polypeptide is substantially higher than that by α‐polypeptide, despite the much greater molecular weight of the latter. This difference in binding affinity was interpreted in terms of the increased conformational adaptability of ε‐polypeptide because of its highly flexible structure. Furthermore, ε‐polypeptide exhibited strong cooperative binding. In addition, the effect of the successive addition of α‐ and ε‐polypeptides on the absorption spectra of methyl and ethyl orange was investigated. The addition of α‐polypeptide with a molecular weight of 400,000 produced a new absorption peak at a shorter wavelength, due to the stacked dye molecules on the polypeptide chain, whereas that of ε‐polypeptide did not. From the results of spectroscopic measurements a possible mode of interaction between these two polypeptides and the small molecule is discussed.
Cationic grafting from carbon black. II. Polymerization of styrene initiated by CO+ClO group on the surface of carbon black
Authors: Tsubokawa Norio
Published: April 2003

The cationic grafting of polystyrene initiated by carbon black containing the CO+ClO group was investigated. The introduction of CO+ClO groups onto a carbon black surface was achieved by the reaction of AgClO4 with carbon black that contained a COCI group. The latter was introduced by the reaction of carboxyl groups with SOCl2. It was found that polystyrene chains could be grown from CO+ClO groups on the surface of carbon black. Moreover, polystyrene was effectively grafted from carbon black: the grafting ratio at 20°C increased to 58% as conversion increased. Furthermore, the grafting ratio and molecular weight of ungrafted polystyrene decreased with an increase in polymerization temperature. These results were explained by the fact that the increasing temperature of the polymerization caused an increase in the rate of chain transfer reaction of the growing polymer chain to the monomer. The carbon black obtained from the reaction produced a stable colloidal dispersion in a good solvent for polystyrene.
Graft polymers with macromonomers. II. Copolymerization kinetics of methacrylate‐terminated polystyrene and predicted graft copolymer structures
Authors: Schulz G. O. , Milkovich R.
Published: April 2003

Copolymerization studies of methacrylate‐terminated polystyrene macromonomers (M1) with several comonomers (M2) verified the modified kinetic scheme and permitted prediction of graft polymer compositions and structures. Instantaneous and cumulative copolymer compositions, average graft distributions, and grafts per molecule are predicted from FORTRAN IV or BASIC programs. The r2 relative reactivity ratios determined from styrene copolymerization (0.61) or from low conversion acrylic monomer in aqueous suspension (∼0.4) had good agreement with literature values (about 0.6 and 0.4, respectively). Decreased macromonomer reactivity determined at high acrylic monomer conversions was attributed to phase separation phenomena. The Macromers also exhibited lower reactivity than predicted when copolymerized with acrylic monomers in DMSO/benzene solutions (r2 ∼ 0.8).
Asymmetric selective polymerization of racemic 1,2‐diphenylethyl methacrylate with the ethylmagnesium bromide‐(−)‐sparteine complex
Authors: Okamoto Yoshio , Yashima Eiji , Hatada Koichi , Yuki Heimei , Kageyama Hiroyuki , Miki Kunio , Kasai Nobutami
Published: April 2003

Asymmetric selective (or stereoelective) polymerization of racemic 1,2‐diphenylethyl methacrylate (DPEMA) with ethylmagnesium bromide (EtMgBr)‐(−)‐sparteine catalyst was studied in toluene at −78°C. In the polymerization (S) enantiomer was consumed preferentially and the enantiomeric excess of initially polymerized (S) enantiomer was consumed preferentially and the enantiomeric excess of initially polymerized DPEMA was greater than 90%. Optically pure (R) monomer was recovered at about 70% polymer yield. Poly(DPEMA) obtained with EtMgBr‐(−)‐sparteine complex was highly isotactic. It was found in the polymerization of optically active DPEMA that optical rotation of poly(DPEMA) was dependent on the tacticity and that isotactic and syndiotactic poly(DPEMA)s showed opposite optical rotations. Circular dichroism spectra of the optically active polymers were measured.
Polymerization of acrylonitrile initiated by ceric ion–citric acid redox system
Authors: Misra G. S. , Bassi P. S. , Abrol S. L.
Published: April 2003

Heterogeneous polymerization of acrylonitrile initiated by ceric ammonium sulfate–citric acid (C.A.) redox system is reported at 35 ± 0.2°C under nitrogen atmosphere. The rate of monomer disappearance is found to be proportional to [C.A.]0, [Ce4+]0.63, and [Monomer]1.59. The rate of ceric ion disappearance is directly proportional to ceric ion concentration but independent of monomer concentration. The initial rate was independent of [H2SO4]. The molecular weight of polyacrylonitrile increases with increasing monomer concentration and decreasing ceric ion concentration. Activation energy was found to be 27.9 kJ/mol.
Low‐temperature thermal decomposition of an epoxy resin
Authors: Grayson Michael A. , Wolf Clarence J.
Published: April 2003

The thermal decomposition of the epoxy resin system, MY720 (70 wt % tetraglycidyl diaminodiphenyl methane), cured with Eporal (diamino diphenyl sulfone), was investigated at 125–215°C. The primary decomposition product was propenal. Several other aldehydes were observed; however, they are formed during cure and are not thermal decomposition products. The apparent activation energy for the production of propenal was 67 kJ/mol (16 kcal/mol). Possible mechanisms for the source of this compound are discussed.
Hydrogen as a chain terminator in continuous gas phase polymerization of propylene
Authors: Ross James F.
Published: April 2003

The effects of hydrogen on both degree and rate of polymerization have been determined for continuous, gas phase polymerization of propylene at industrial reactor conditions. The effects of molecular weight using three modifications of TiCl3–DEAC catalyst are correlated by Natta's equation, using number average molecular weights determined from polymer melt flow rate. The coefficients of Natta's equation, when correlated against temperature in Arhenius plots, imply that the most active catalyst is diffusion controlled because the activation energy is abnormally low. Hydrogen increases overall polymerization rate. Rate is correlated by modification to Natta's equation that accounts for hypothesized increase in active sites on catalyst surface due to adsorbed molecular hydrogen.
Studies on vinyl photopolymerization using a macromolecular C.T. Complex between poly(N‐vinyl carbazole) and bromine as the photoinitiator
Authors: Ghosh Premamoy , Ghosh Tapas Kumar
Published: April 2003

Photopolymerization of methyl methacrylate (MMA) was studied at 40°C using a macromolecular C.T. Complex between poly(N‐vinyl carbazole) and bromine, expressed in brief as (PNVC–Br2) complex, as the photoinitiator. Initiator exponent was 0.40 for [PNVC–Br2] ≤ 2.5 × 10−3 mol L−1 and practically zero for [PNVC–Br2] > 2.5 × 10−3 mol L−1. Monomer exponent in different diluent systems such as benzene, carbon tetrachloride, and acetone was close to 1.0. Low initiator exponent (<0.5) is explained on the basis of an initiator‐dependent termination mechanism, in addition to the usual bimolecular termination. Analysis of kinetic data indicates that the initiator‐dependent termination is primarily due to degradative initiator transfer and that due to primary radicals is considered inconsequential in view of monomer exponent being close to unity. The non‐ideal termination process assumes over‐whelming prominence at high [PNVC–Br2].
Synthesis and polymerization of optically active L‐[α‐(N‐p‐acryloxybenzoyl)alanine ethyl esters]
Authors: Lu Chengxun , Overberger C. G.
Published: April 2003

New optically active monomers L‐[α‐(N‐p‐acryloxybenzoyl)alanine ethyl esters] (I) and their polymers were synthesized. The title monomers (I) were prepared by the reaction of 1‐p‐acryloxybenzoyloxy‐4‐chlorobenzotriazoles (II) with L‐alanine ethyl ester hydrochloride, by aminolysis of the active monoester. The new typical active ester (II) was synthesized by the N‐hydroxy compound active‐ester methods in excellent yield. Before the synthesis of the optically active monomers was carried out, a model study of the aminolysis of the two active esters was performed.
Electron spin resonance studies of spin labeled alternating functional copolymers
Authors: Andreis M. , Veksli Z. , Vuković R. , Fleš D.
Published: April 2003

The spin‐labeled and spin‐probed alternating copolymers of poly(phenylvinyl alkyl ethers) with various alkyl groups (Me, Et, sec‐Bu) in the ether moiety were investigated by electron spin resonance (ESR). Measurements were taken in different solvents over a wide range of concentration. Studies reveal that the molecular motion of spin‐labels and spin‐probes depends on the bulkiness of the alkyl group at the solvent concentration in which the effect of segmental rotation is dominant. The implication of the type of chemical bonding on the nitroxide motion is discussed.
Reactions in the presence of organic phosphites, I: High temperature amidation in the absence of solvents
Authors: Aharoni Shaul M. , Hammond Willis B. , Szobota John S. , Masilamani Divakar
Published: April 2003

When reacted for periods of 5–10 min at temperatures of about 280–300°C in the presence of certain organic phosphites polymers that contain available carboxy and aliphatic amine groups undergo amidation. This reaction can increase the molecular weight of many aliphatic polyamides by their self‐reaction in an extruder. Block or graft copolymers can be formed by reacting polymers that contain aliphatic amines with others that contain carboxyl. Studies of model compounds in the companion article (II) indicate that polymerization proceeds through an diaryloxy or dialkoxy amino phosphine intermediate to produce amide bonds and disubstituted phosphite reaction by‐products. In the absence of primary amines in the reaction mixture an ester is slowly formed from the carboxyl end group of the polymer and the oxysubstituent of the phosphite. In no case was a phosphorus‐containing mixed anhydride detected. The mechanistic identity of the low temperature reactions in article II and the high temperature reactions in this article has not been proved conclusively, however.
Ablative photodecomposition of polymer films by pulsed far‐ultraviolet (193 nm) laser radiation: Dependence of etch depth on experimental conditions
Authors: Srinivasan R. , Braren Bodil
Published: April 2003

Data on the ablative photodecomposition of three condensation polymers [polyimide, poly(ethylene terephthalate), and polycarbonate] and one addition polymer (polymethyl methacrylate) by laser pulses at 193 nm are presented. The etch depth/pulse is a linear function of the number of pulses at constant laser fluence. It varies with the logarithm of the fluence in a linear manner at different fluences. The etch depth is independent of the atmosphere above the film, whether it is air at 1 atm, or a vacuum. The etching of PMMA at fluences > 100 mJ/cm2 is believed to follow a mechanism different from the process at lower fluences. Etching of polyimide and polyethylene terephthalate at 248 and 308 nm is also reported. The mechanism of etching by laser radiation may receive greater contribution from a thermal process with increasing wavelength. This is manifested in the etch depth versus log fluence plot by sharp changes in slope.
Catalyseurs Ziegler‐Natta supportés sur MgCl2 pour la polymérisation stéréorégulée du propène. III. Systèmes catalytiques à hautes performances comprenant un solide ternaire: MgCl2, ester aromatique, TiCl4
Authors: Spitz R. , Lacombe J. L. , Guyot A.
Published: April 2003

An examination of the precatalyst which contains three compounds (MgCl2–TiCl4‐aromatic ester) uncovered numberous properties that apparently are common to all precatalysts and have already been observed in the simpler systems: a continous decrease in the polymerization rate during polymerization, characterized by a deactivation index that does not depend on the precatalyst but only on the cocatalyst; isotacTiClty control by the [AI]/[aromatic ester] ratio in the cocatalytic solution; and fast and reversible control of kinetics and tacTiClty by the same ratio. The precatalyst prepared by impregnation of the aromatic ester in MgCl2 or MgCl2–TiCl4 presents moderate or no improvement when compared with the simpler MgCl2–TiCl4 catalysts. The yellow precatalyst prepared by milling MgCl2 with the aromatic ester and impregnating with TiCl4 are the only products that provide high activity and isotactic index above 95% simultaneously, as revealed by the patent literature. Interpretation of the role played by the electron donor, based on infrared studies, are proposed: in the precatalyst it controls fixation of TiCl4 on MgCl2; in the cocatalytic solution it regulates the isospecificity of the active site by contact with the alkylaluminium‐aromatic ester complex and slows polymerization. Free electron donor gradually poisons the active centers.
Applicability of the Mayo–Lewis equation to high conversion copolymerization of styrene and methylmethacrylate
Authors: O'Driscoll K. F. , Kale L. T. , Rubio L. H. Garcia , Reilly P. M.
Published: April 2003

In contradiction to reports from this and other laboratories, this study reports that the integrated Mayo–Lewis equation, or Meyer–Lowery equation, adequately describes the high‐conversion free radical copolymerization of styrene and methylmethacrylate. The copolymerization was monitored by following the changes in the feed composition using NMR, as well as determination of the resulting copolymer compositions by NMR and UV. “Error in all Variables” statistical techniques were used to produce estimates of the reactivity ratios. The reactivity ratios estimated were, from feed composition, NMR, r1 (styrene) = 0.472, r2 = 0.454, from copolymer composition, UV, r1 = 0.497, r2 = 0.464, and NMR, r1 = 0.432, r2 = 0.422.
PVC miniemulsion polymerization II. Particle and droplet growth as a function of conversion
Authors: Dewald R. C. , Hart L. H. , Carroll W. F.
Published: April 2003

Growth of two droplet families and a polymer seed family as a function of percent monomer conversion in PVC miniemulsion synthesis demonstrates that polymerization in droplets predominates to ∼ 30–40% conversion, whereupon polymerization of seed becomes favored. This difference appears to be due to a liquid‐to‐solid phase change in the forming particles during the course of polymerization.
Copolymerization reactivity of poly(methyl methacrylate) macromer
Authors: Fukutomi Takashi , Yokota Atsushi , Ishizu Koji
Published: April 2003

Poly(methyl mehtacrylate)(PMMA) macromers with several vinyl groups at both chain ends were synthesized by the mechanical scission reaction of the main chain in the presence of p‐divinylbenzene(p‐DVB). The radical copolymerization of this macromer with styrene(St) or MMA was carried out in benzene at 60°C and the reactivity ratio of both monomers (r2) was calculated from a kinetic scheme of copolymerization. As a result, the effect of molecular weight and concentration of macromers was not observed in both copolymerization systems. The value of r2, however, decreased as the number of end vinyl groups in a macromer (N) increased. These results are discussed in some detail as we describe the construction of the kinetic model of copolymerization.
Polyimides from dianhydrides and bis(p‐aminophenyl) alkane diamines. I
Authors: Ghatge N. D. , Shinde B. M. , Mulik U. P.
Published: April 2003

Polyimides were synthesized from pyromellitic dianhydride (PMDA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and three different diamines with the following general structure:
magnified image
where R is ethyl, propyl, or isobutyl. The poly(amic acids) obtained had inherent viscosities ranging from 0.30 to 0.93 and were thermally/chemically converted to polyimides. The thermal stability of the polyimides was evaluated by using dynamic thermogravimetric analysis in air. Physical and thermal properties of these polyimides were compared with that obtained by reacting 2,2‐bis(4‐aminophenyl) propane and PMDA/BTDA.
Transcrystallinity in polypropylene
Authors: Huson M. G. , McGill W. J.
Published: April 2003

A study using hot‐stage microscopy and differential scanning calorimetry in assessing the ability of a number of substrates to nucleate transcrystalline growth in polypropylene is reported. Surface energy, chemical composition, crystal morphology, and moisture content of the substrate are discounted as being of importance in determining the ability of a substrate to nucleate polypropylene. It is concluded that surface topography plays a major role and it is argued that a prealignment of polymer chains occur in suitably sized cracks or channels on the surface. The rate of cooling the melt also dramatically influences the nucleating activity of a surface and this is ascribed to interfacial stresses resulting from differential contraction.
DSC studies of phase transitions in poly(diethylsiloxane)
Authors: Papkov V. S. , Godovsky Yu. K. , Svistunov V. S. , Litvinov V. M. , Zhdanov A. A.
Published: April 2003

The differential scanning calorimetry studies have shown that high‐molecular linear poly(diethylsiloxane) can exist in two high‐temperature polymorphs which melt at 280 and 290 K. The heats of fusion of the high‐temperature polymorphs are 17 and 21 J/g, respectively. Each of the high‐temperature forms arises from the corresponding low‐temperature form the corresponding low‐temperature form when the polymer is heated: the first at 214 K (transition heat is 28 J/g) and the second at 206 K (transition heat is 26 J/g). The mesophase formed from the molten high‐temperature crystalline phases melts in a rather broad temperature range of 290 to 327 K, and the heat of this transition is 2.7 J/g. Crystallization of poly(diethylsiloxane) from the mesomorphic and the supercooled amorphous state is different. In the first case, apparently, the whole mesophase is converted to the crystalline phase and the samples have a crystallinity near 1. In the second case the crystallinity is only ca. 0.3. The temperature range in which the mesophase melts depends on the molecular weight of the polymer, presence of crosslinks and the conditions under which it has been formed, e.g., temperature.
Study of copolymer–copolymer interactions and formation of intermacromolecular complexes
Authors: Chatterjee S. K. , Malhotra A. , Yadav D.
Published: April 2003

Interpolymer complex formation has been studied between methacrylic acid‐methacrylamide copolymer and acrylic acid–acrylamide copolymer. The respective co‐monomer units of the two copolymers enter into complex formation through H‐bonding and ion dipole interactions. The unreacted units in the copolymer complex also interact with homopolymers such as PEO and PVP to form ternary complex. Formation of complexes and replacement reactions could be shown through several experimental techniques, e.g., viscometry, conductometry, and potentiometry.
Modification mechanism in olefin polymerization catalysts TiCl4/MgCl2–aromatic ester–Al(C2H5)3
Authors: Kissin Y. V. , Sivak A. J.
Published: April 2003

An IR/UV study of the interaction between ethyl benzoate and Al(C2H5)3 in dilute heptane solution at 25–75°C demonstrated that the ester is readily reduced under these conditions with the formation of two aluminum dialkyl alkoxides, Al(C2H5)2 and Al(C2H5)2OC(C2H5)2C6H5, as major products. Rate constants of the reduction of the initial AI(C2H5)3 · ester complex by free AI(C2H5)3 are 2.9 (26°C), 14.4 (50°C), and 59.6 (75°C) L/mol min; Eact = 52.0 kj/mol. Study of propylene polymerization with this catalytic system at 50°C showed that preliminary aging of the AI(C2H5)4–ethyl benzoate mixtures at 25°C for 24 h and at 50°C for 2 h does not adversely affect catalyst performance. These data suggest that the possible actual modifier in this catalytic system is aluminum alkoxide with a highly branched tertiary alkoxy group.
Preparation of polysiloxanes from silicic acid. VII. Effects of the degree of esterification and alkyl groups on condensations of silicic acid esters and formation of fibrous silica
Authors: Abe Yoshimoto , Shintani Nobuhiro , Misono Takahisa
Published: April 2003

Silicic acid esters were prepared by the reaction of the silicic acid in tetrahydrofuran with various alcohols such as such as methanol, ethanol, 2‐propanol, 1‐butanol, 2‐methyl‐2‐propanol and 1‐octanol, using an esterification apparatus designed especially to allow the preparation of silicic acid esters from alcohols with low boiling points or appreciable steric hindrance. With the intent of obtaining a spinnable ester solution by condensation of silicic acid esters, the effects of the degree of esterification (DE) and alkyl group on gel time and spinnability are investigated. An increase in the DE and the size of the alkyl group led to an increase in the gel time of the esters. Esters solutions with a good spinnability were prepared from n‐butyl and isopropyl esters with DEs of 40–50%. In addition, the gel permeation chromatography of condensing esters with low DEs showed a rapid increase in molecular weight. The results showed that spinnability depended on DE and the ester's alkyl group. Fibers could be formed with length of about 10–100 cm from ethyl, isopropyl, and n‐butyl esters with DEs 40–50% and with length of 10 cm from octyl ester with DE 26%.
Long‐lived polymer radicals. VI. Polymerization of N‐methylmethacrylamide with formation of living propagation radicals
Authors: Sato Tsuneyuki , Miyamoto Jiro , Otsu Takayuki
Published: April 2003

The polymerization of N‐methylmethacrylamide (NMMAm) with azobisisobutyronitrile (AIBN) was investigated kinetically in benzene. This polymerization proceeded heterogeously with formation of the very stable poly(NMMAm) radicals. The overall activation energy of this polymerization was calculated to be 23 kcal/mol. The polymerization rate (Rp) was expressed by: Rp = k[AIBN]0.63‐0.68[NMMAm]1−2.5. Dependence of Rp on the monomer concentration increased with increasing NMMAm concentration. From an ESR study, cyanopropyl radicals escaping the solvent cage were found to be converted to the living propagating radicals of NMMAm in very high yields (ca. 90%). Formation mechanism of the living polymer radicals was discussed on the basis of kinetic, ESR spectroscopic, and electron microscopic results.
Aromatic polyamides. XI. Effect of the halogen substitution on the thermal and flammability behavior of poly(1,4‐phenylene terephthalamide)
Authors: Kapuscinska M. , Pearce E. M.
Published: April 2003

This article concerns the synthesis and characterization of poly(1,4‐phenylene terephthalamide) and halogenated derivatives thereof. It was found that the halogen substitution affected significantly the thermal characteristic and flame resistance of that polyamide. In a nonoxygen atmosphere two‐step decomposition process for the halogenated, while only one‐step for unsubstituted polyamides were observed. The results supported the previous suggestion, that in the case of the halogenated polyamides the char yield enhancement and the flame resistance improvement are associated with halogen release and ring‐forming reactions during their pyrolysis.
Reactivities of carboxylic acid vinyl monomers differentiated by the aggregation forms and their simple molecular orbital interpretation
Authors: Kuzuya Masayuki , Kawaguchi Tohru , Daikyo Toshiya , Okuda Takachiyo
Published: April 2003

Plasma‐exposed solution polymerizations of carboxylic acid vinyl monomers [methacrylic acid (MAA) and acrylic acid (AA)] in carbonyl solvents were found to be highly efficient, particularly in high‐temperature postpolymerizations. Thermal polymerizations in these solvents were also accelerated to a considerable extent. Obviously the carbonyl solvents and/or the increased temperature caused the monomer aggregates to accelerate the rate of polymerization.

The molecular orbital features of the simple models of monomer aggregates, that is, the monomeric form, singly hydrogen bonded open‐dimer and doubly hydrogen bonded cyclicdimer of MAA and AA, supported by the CNDO/2 method, were capable of distinguishing the variations in the reactivities of the aggregates; the open‐dimer was shown to be responsible for the enhanced reactivities under the abovementioned conditions.
Crystallizable elastomers by chemical modification of transtactic polydiolefins. Hydrochlorination
Authors: Bruzzone Mario , Carbonaro Antonio
Published: April 2003

Solutions of crystalline, high‐melting trans‐1,4 polybutadiene (trans‐PB), trans‐1,4 mix 1,2 butadiene‐piperylene copolymer (BPC, low piperylene content), and isotactic trans‐1,4 piperylene (trans‐PP) were partly hydrochlorinated under mild conditions with gaseous HCl. Glass transition and melting temperatures were strongly affected by the addition of HCl. Several hydrochlorinated trans‐PB and ‐BPC were semicrystalline or amorphous elastomers, susceptible to reversible crystallization when stretched. The straininduced crystallinity was similar to that shown by trans‐polybutadiene sequences, particularly in the form that is unstable in bulk at room temperature (form II). The addition of HCl to the asymmetric double bond in trans‐PP occurs in a stereoselective way, according to 13C‐NMR. under the experimental conditions of the present study the occurrence of side reactions was observed; these reactions decrease the polymer unsaturation to a lower level than that calculated by the amount of HCl added to the polymer.
Epoxy functional copolymers as biospecific adsorbents for purification of enzymes
Authors: Dhal Pradeep K. , Babu G. N. , Sudhakaran S. , Borkar P. S.
Published: April 2003

The affinity chromatographic characteristics of some chemically modified copolymers based on glycidyl methacrylate have been evaluated. The copolymers were modified by means of reaction of suitable ligands with epoxy groups. Purification of pencillin acylase was carried out using these matrices as the stationary phase in the chromatographic column. Effect of the nature of the ligands and pH on the binding and desorption efficiency of the enzyme was evaluated.
Polymeric nucleophiles and cosolvents. The reactivity of poly(ethylene glycol) and its derivatives with benzyl bromide under solvolytic conditions
Authors: McManus Samuel P. , Yorks Kathy , Harris J. Milton
Published: April 2003

Pseudo first‐order rate constants for the solvolytic displacement of benzyl bromide in 100% ethanol and in 80 and 60% aqueous ethanol (v/v) are reported. The effect of adding poly(ethylene glycol) (PEG) and PEG dithiols and diamines to the solvolytic solutions has been studied. The solvolytic rates are mildly retarded on adding PEG, MW 950, or PEG dimercaptoacetate, MW 548 or 748 (at a concentration of about 8% of the polymer) to reactions in absolute ethanol. In 80% ethanol, however, a rate acceleration by the polymers was observed, with the thiols exhibiting the largest effects. PEG di(3‐mercaptopropionate) reacts slightly faster than the PEG dimercaptoacetates, but liberated acid affects the former's reaction. Three molecular weights of primary diamines structurally derived from propylene oxide‐capped PEG were evaluated and found to increase solvolytic rates of benzyl bromide significantly. Kinetic evaluation and comparisons with reactions containing equivalent amine groups per gram in an appropriate model (ethanolamine) revealed that the polymer's amine groups are actively involved nucleophilically. Grunwald‐Winstein plots and second‐order rate constants revealed that the polymeric diamines caused the benzyl bromide to undergo polymer‐assisted displacement in all solvent compositions. Since it was noted that the second‐order rates increased as the PEG amine molecular weight increased, it appears that the PEG framework may be assisting the reaction.
The influence of power and substrate temperature on chemical composition, determined by ESCA, of the inductively coupled RF plasma polymerization of acrylonitrile
Authors: Munro H. S. , Grünwald H.
Published: April 2003

The influence of power and substrate temperature on the chemical composition of inductively coupled RF plasma‐polymerized films of acrylonitrile was monitored by ESCA. At a substrate temperature of 20°C a minimum in nitrogen content as a function of power was observed for films deposited in the coil region. A maximum was observed for a substrate temperature of 150°C. When power was increased from 1 to ∼50 W a linear increase in nitrogen content was observed in the tail region at both substrate temperatures. A step function observed in the C1s and N1s core‐level spectra is discussed in terms of extensive unsaturation being present in the films.
Sulfonated polystyrene ionomers prepared by emulsion copolymerization of styrene and sodium styrene sulfonate
Authors: Weiss R. A. , Turner S. R. , Lundberg R. D.
Published: April 2003

Sulfonated polystyrene (S–PS), which is of considerable scientific and technological interest, has been traditionally prepared by the sulfonation of preformed polystyrene. This report describes the preparation and properties of S–PS prepared by emulsion copolymerization of styrene and sodium styrene sulfonate. S–PS prepared by copolymerization gave solubility, solution behavior and thermal characteristics that are consistent with an ionomeric structure. The solubility characteristics indicated some chain‐to‐chain sulfonate heterogeneity. Thermal analysis studies indicated that the glass transition does not increase with increasing sulfonate content. This is contrary to what has been observed for S–PS prepared by sulfonation and suggests that the S–PS prepared by copolymerization is fundamentally different in structure than S–PS prepared by sulfonation of polystyrene.
The emulsion copolymerization of styrene and sodium styrene sulfonate
Authors: Turner S. Richard , Weiss R. A. , Lundberg Robert D.
Published: April 2003

The emulsion copolymerization of styrene and sodium styrene sulfonate has been shown to be a feasible preparative route to ionomeric sulfonated polystyrene. The properties of these copolymers are reported elsewhere. The copolymerization rate was found to be dramatically enhanced when compared to that for the emulsion copolymerization of styrene under identical conditions. This copolymerization was studied in detail and two mechanisms were proposed to account for these rate differences. An increase in the number of polymerizing particles in the copolymerization with consequent rate enhancement was substantiated by electron microscopy. However, the data indicate that the rate differences cannot be fully accounted for by this effect. In addition, a gel effect is proposed as a second contributor to the enhanced rate. This gel effect is believed to result from the intermolecular association of the incorporated metal sulfonate units in the growing polymer particles. When a third monomer that plasticizes the ionic interactions is used the polymerization rate decreases. This supports the gel effect hypothesis.
Comparisons of styrene ionomers prepared by sulfonating polystyrene and copolymerizing styrene with styrene sulfonate
Authors: Weiss R. A. , Lundberg R. D. , Turner S. R.
Published: April 2003

As part of a continuing study of ion‐containing polymers, a comparison has been made on styrene‐based sulfonate ionomers obtained by two different processes. Copolymers of styrene with sodium styrene sulfonate (SSS) have been compared with corresponding polymers obtained by the sulfonation/neutralization of preformed polystyrene (S–PS). The former system covered a range of sulfonate level from 1 to 30 mol %, while the latter ranged from about 1 to 7 mol %. The characterization of these materials has been conducted using solubility behavior, dilute solution viscometry, thermal mechanical analysis, density measurements, and water adsorption studies. At low (ca. 1%) levels the solubility behavior of the SSS copolymers and the sulfonated polystyrenes were similar. However, at higher sulfonate levels the solubility behavior in different solvents and the dilute solution viscometry were significantly different for the two systems. Similarly, thermal analysis studies (DSC) showed that the glass transition of the sulfonated polystyrene increased linearly with sulfonate level, while the Tg for the SSS copolymer increased modestly, up to about 7 mol % sulfonate content, and then remained constant. Significant differences in the softening behavior and water absorption characteristics were also observed for these two classes of ionomers. Although molecular weights and molecular weight distributions are not now available for these ionomers, the differences in their behavior does not appear to be due simply to differences in molecular weight. It is postulated that the differences in the copolymer and the S–PS ionomers may originate with differences in sulfonate distribution. It is suggested that the SSS monomer units are incorporated as blocks in the copolymer as opposed to a more random distribution in the S–PS ionomer. Indirect evidence in support of his argument is found, for example, in the case of the copolymer in the solubility behavior, the relative independence of Tg on sulfonate concentration and the apparent existence of a second, high temperature transition tentatively attributable to an ion‐rich phase. Additional studies are required to confirm this hypothesis.
Magnesium chloride supported high mileage catalyst for olefin polymerization. VI. Definitive evidence against diffusion limitation
Authors: Chien James C. W. , Kuo Chi‐I , Ang Tsunle
Published: April 2003

There has been continuing interest in the possible role of insoluble polymer products forming a barrier reducing rate of diffusion of monomer to the active site to cause decrease in rate of polymerization and broadening of molecular weight distribution. This possibility is more acute the higher the catalytic activity. We have now shown that diffusion limitation is unimportant for the MgCl2 support high activity Ziegler–Natta catalyst by comparing its polymerization of propylene to isotactic insoluble polypropylene and of decene‐1 to isotactic soluble polydecene. The rate constant of propagation is about eight times greater for propylene while the rate constants of termination, i.e, decay of Rp, are comparable for the two monomers.
13C‐NMR spectral studies on the distribution of substituents in water‐soluble cellulose acetate
Authors: Miyamoto Takeaki , Sato Yukiko , Shibata Toru , Tanahashi Mitsuhiko , Inagaki Hiroshi
Published: April 2003

The degree of substitution (DS) and distribution of O‐acetyl groups of water‐soluble cellulose acetate (CA) were investigated by 13C‐NMR. For this purpose, three different series of CA samples with low DS were prepared by respective homogeneous reaction, i.e., (1) deacetylation of cellulose triacetate (CTA) in acetic acid—water solution (D‐series), (2) reaction of CTA with hydrazine (H‐series), and (3) acetylation of cellulose with acetic anhydride in a 10% LiCl‐dimethylacetamide solution (A‐series). It was found that (i) water‐soluble CA can be obtained only from D‐series products, (ii) the DS value of water‐soluble CA ranges from 0.5 to 1.1, (iii) the D‐series products exhibit little difference between the relative DS values at C‐2, C‐3 and C‐6 hydroxyl groups, and (iv) the relative DS at C‐6 hydroxyl groups is very high compared to those at C‐2 and C‐3 hydroxyl groups in H‐ and A‐series products. Aqueous solution of water‐soluble CA (D‐series sample) showed no gel—sol transition, even when the temperature was raised to 95°C. X‐ray diffraction observations revealed that the water‐soluble D‐series samples were essentially noncrystalline, but the water‐insoluble A‐series samples were crystalline. It was also found that the relative ease of acetylation is C‐6 > C‐2 > C‐3.
Ring‐opening polymerization of 2‐azabicyclo‐[2,2,1]‐hept‐5‐en‐3‐one using metathesis catalysts
Authors: Cho Hyun‐Nam , Choi Sam‐Kwon
Published: April 2003

The ring‐opening polymerization of an unsaturated bicyclic lactam, 2‐azabicyclo‐[2,2,1]‐hept‐5‐en‐3‐one (ABHEO), was carried out using metathesis catalysts under various reaction conditions. It is observed that the best results (34% conversion and ηinh: 0.18 dL/g) were obtained when the mole ratios of ABHEO to WCl6 as a catalyst and WCl6 to AlEt3 as a cocatalyst were 200 and 4, respectively. The infrared (IR) and nuclear magnetic resonance (1H‐ and 13C‐NMR) spectra of the polymer obtained indicated that the ABHEO was transformed to the ring‐opened polymer, poly(2‐pyrrolidone‐3,5‐diylvinylene) [poly(ABHEO)]. The resulting polymer was amorphous as determined by DSC analysis, which showed only secondary transition at 100°C.
Inhibition of acrylic acid polymerization by phenothiazine and p‐methoxyphenol
Authors: Levy Leon B.
Published: April 2003

The major features of polymerization induction periods for acrylic acid inhibited with phenothiazine and p‐methoxyphenol have been characterized at 100°C, including duration of the induction periods, and rates of inhibitor disappearance, molecular oxygen absorption, and peroxide formation. Surprisingly, thermally produced radicals react more rapidly with phenothiazine than with oxygen since there is no detectable oxygen absorption or peroxide for mation during phenothiazine‐induced induction periods. Thus, phenothiazine has been used to estimate the thermal rate of radical formation. Phenothiazine's effectiveness as an inhibitor is not directly affected by oxygen, although it does undergo oxygen‐promoted, noninhibition‐related side reactions. p‐Methoxyphenol, on the other hand, depends entirely on the presence of oxygen to function as an inhibitor. Compared with equivalent concentrations of p‐methoxyphenol, induction periods obtained with phenothiazine are very long, and the rate of inhibitor disappearance is slower by at least an order of magnitude. The characteristics of p‐methoxyphenol inhibition reflect a greater radical flux deriving from the significant rates of oligomeric peroxide formation and decomposition which we measured during p‐methoxyphenol‐induced induction periods at 100°C. MEHQ is an effective inhibitor at ambient temperatures in part because of the greater stability of the peroxides at these lower temperatures.
The synthesis and some properties of nylon 4,T
Authors: Gaymans R. J.
Published: April 2003

The synthesis of nylon 4,T from tetramethylenediamine and a terephthalic acid derivative was studied in a two step‐process: prepolymerization, followed by postcondensation in the solid state (4 h, 290°C). The prepolymers were prepared by the nylon salt method, ester polymerization method, interfacial method, and a low temperature solution method. A maximum ηinh of 1.52 was obtained. From a solution in trifluoroacetic acid, films were cast and on these films we studied its IR spectrum, WAXS, and melting behavior with DSC. A boiled up sample had a double melting transition at 434 and 475°C and a ΔH0 of 130 J/g.
Synthesis of polyamides by direct polycondensation with (1,2‐benzisoxazol‐3‐yl) diphenyl phosphate as a new activating agent
Authors: Ueda Mitsuru , Oikawa Hideaki
Published: April 2003

A new activating agent for amide condensations, (1,2‐benzisoxazol‐3‐yl) diphenyl phosphate (1), was readily prepared in high yield by the reaction of 1,2‐benzisoxazol‐3‐ol (2) with diphenyl phosphorochloridate (3) in the presence of triethylamine in benzene. The new activating agent 1 was found to be very useful for the preparation of amides from carboxylic acids and amines. The direct polycondensation of several dicarboxylic acids with aromatic diamines using the activating agent 1 in the presence of triethylamine proceeded slowly at room temperature to produce polyamides with inherent viscosities up to 1.2 dL g−1.
Polybismaleimide containing tetrakisphenoxycyclotriphosphazenes
Authors: Kumar Devendra
Published: April 2003

A heat‐resistant polybismaleimide was obtained by the thermal polymerization of bis(maleimidophenoxy)‐ tetrakis(phenoxy)cyclotriphosphazene. The thermal stabilities of the polybismaleimide were evaluated in nitrogen and in air by thermogravimetric analysis. The polybismaleimide was stable to 340°C and has char yield of 70% at 800°C in nitrogen and of 60% at 700°C in air. The monomer bismaleimide was obtained by the reaction of bis(4‐aminophenoxy)tetrakis(phenoxy)cyclotriphosphazene with maleic anhydride. The diamine was synthesized by a stepwise reaction of hexachlorocyclotriphosphazene with phenol and 4‐nitrophenol to give bis(4‐nitrophenoxy)tetrakis(phenoxy)cyclotriphosphazene and reducing the nitro groups. The structure of the cyclotriphosphazenes were characterized using Fourier transform infrared (IR), proton nuclear magnetic resonance (1H‐NMR) spectroscopy, and elemental analysis.
Preparation and reactions of polymeric azides. III. The preparation and reactions of polymeric phosphine imines
Authors: Cohen H. L.
Published: April 2003

Polymeric azides reacted with triphenylphosphine to give the corresponding phosphine imines, which reacted with bases, aldehydes, and isocyanates to give amines, imines, and carbodiimides, respectively.
Synthesis and characterization of the new thermosetting monomers and phthalocyanine polymers with ester—imide linkages
Authors: Achar B. N. , Fohlen G. M. , Parker J. A.
Published: April 2003

The study described here deals with the methods of synthesis of two new bisphthalonitrile derivatives with ester—imide linkages and their polymerization. Optimum conditions for the synthesis and characterization of the bisphthalic anhydrides, bisphthalonitriles, and polymers are developed using IR spectral, differential scanning calorimetric, dynamic thermogravimetric analytical, and mass spectral studies. These new polymers showed good thermal stability and chemical inertness. The polymers showed char yield of 50% at 800°C in nitrogen atmosphere. These thermosetting phthalocyanine polymers are expected to be useful in various applications such as the production of moulded articles and laminates.
The cationic polymerization and copolymerization of isopropenylmetallocene monomers
Authors: Gonsalves Kenneth , Zhan‐Ru Lin , Lenz Robert W. , Rausch Marvin D.
Published: April 2003

Three types of isopropenylmetallocene monomers were synthesized and subjected to polymerization and copolymerization by cationic initiators; (1) isopropenylferrocene (IF); (2) (η5‐isopropenylcyclopentadienyl)dicarbonylnitrosylmolybdenum (IDM); and (3) 1,1′‐diisopropenylcyclopentadienylstannocene (DIS), and related derivatives of each. IF was synthesized by a three‐step procedure involving the acetylation of ferrocene, conversion of the latter to 2‐ferrocenyl‐2‐propanol, and dehydration of the carbinol. IF was homopolymerized under various cationic initiation conditions, but only low molecular weight homopolymers were obtained. Copolymerization of IF with styrene and with p‐methoxy‐α‐methylstyrene also gave only low molecular weight products. The formation of only low molecular weight polymers in all polymerization reactions is believed to result from the effect of the unusually high stability of ferrocenyl carbenium ions on its propagation reaction. The observed polymerization behavior of α‐trifluoromethylvinylferrocene is in accord with this conclusion. IDM and DIS did not form polymeric products under cationic conditions, although copolymers could be obtained for each of these monomers and styrene with a free radical polymerization initiator (AIBN).
Ethylene—polyethylene mixture: Saturated liquid densities and bubble pressures up to 26.1 MPa and 493.1 K
Authors: Rousseaux P. , Richon D. , Renon H.
Published: April 2003

Measurements of saturated liquid densities and ethylene solubilities in ethylene—polyethylene systems up to 26.1 MPa and 493.1 K were obtained using a new variable‐volume static cell after a careful investigation of the influence of inhibitors of polymerization of ethylene under experimental conditions.