bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal oxidative degradation of isotactic polypropylene catalyzed by copper and copper oxide interfaces
Authors: Jellinek H. H. G. , Kachi H. , Czanderna A. , Miller A. C.
Published: April 2003

The oxidative degradation of isotactic polypropylene films coated on well‐defined Cu(Cu2O), CuO0.67, and CuO films in a temperature range of 90–120°C in a quartz‐spoon‐gauge‐reaction vessel was studied. This catalytic reaction has been compared with the oxidation of polypropylene without copper or oxide films. The reaction vessel contained, if needed, P2O5 and/or KOH as “getters” for H2O and CO2, these substances could be menitored continuously. Cu(Cu2O) films were transformed during oxidation of the polymer to yellow CuO0.67 below 100°C and above this temperature to black CuO in the presence of H2O and CO2, whereas in the absence of these compounds CuO was formed below 100°C and CuO0.67 at 120°C. Characteristic autoxidation curves obtained in the absence of H2O and CO2 showed induction periods that were shorter for copper oxide‐polymer interfaces than for glass‐polymer interfaces (i.e., for uncatalyzed oxidation). Abnormalities were observed for Cu(Cu2O)‐polymer interfaces because of further oxidation of Cu during the reaction. The rates of oxygen consumption were faster for CuO0.67‐polymer and CuO‐polymer than for the uncatalyzed reaction; the catalytic action of CuO0.67 was somewhat larger than that of CuO. The important observation was made that the mechanism of oxidation is not the same in the absence and presence of reaction products; that is, H2O and CO2. This was confirmed by ion beam scattering experiments, which also revealed that an oxidation‐reduction process takes place at Cu and their oxide interfaces. A mechanism for the catalytic oxidation process, based on the ease by which copper ions are released from the metal oxides at the interface, was formulated. These ions diffuse subsequently as actions of carboxylate anions into the bulk of the polymer. Arrhenius equations of oxygen consumption are given for all cases; the energy of activation calculated for the initiation of the uncatalyzed oxidation agrees with its literature value. The energy of activation for the initiation of the catalyzed reaction was a few kilocalories lower than that for the uncatalyzed reaction. Catalytic action is mainly operative for the initiation reaction at the interface and for the decomposition of hydroperoxides by copper ions. Preventing the delivery of copper ions to the polymer would be the most efficient way of inhibiting the catalysis.
Dual role of a hydroxyphenylbenzotriazole UV absorber in the photooxidation of wool
Authors: Leaver I. H. , Waters P. J. , Evans N. A.
Published: April 2003

The protective effect of the UV absorber, sodium 2‐(2′‐hydroxy‐5′‐methylphenyl)benzotriazole sulfonate, on the light stability of wool has been examined. The degree of protection, as measured by the reduction in the rate of photoyellowing of the fiber, is highly dependent on both the spectral composition of the light source and the pH at which the absorber is applied to the fiber. This is due mainly to traces of the deprotonated, phosphorescent form of the absorber which can sensitize the photooxidation of wool in visible light, hence counteracting the photostabilizing influence of the UV absorber.
Polymerization of t‐butyl thiirane. I. Stereoelective polymerization of the racemic monomer
Authors: Dumas Philippe , Spassky Nicolas , Sigwalt Pierre
Published: April 2003

The stereoelective polymerization of racemic t‐butyl thiirane was performed with chiral zinc glycolate. Monomers and polymers of high optical purities were isolated. A new kinetic scheme in which the ratio of the rates of consumption of both enantiomers obeys a second‐order relationship is proposed. This behavior is different from that observed for other three‐membered ring monomers.
Photocrosslinking of elastomer systems. I. UV light‐induced reactions in a blend of EPDM‐benzoin derivatives
Authors: Bousquet Jean‐Alain , Faure Jean , Fouassier Jean‐Pierre , Donnet Jean‐Baptiste , Haidar Bassel , Vidal Alain
Published: April 2003

Photocrosslinking experiments were performed on elastomeric polymer films (EPDM) that contained benzoin derivatives as photosensitive initiators. Infrared (IR) and ultraviolet (UV) spectroscopy investigations were used in conjunction with physical property measurements. The results all together make it possible to discuss the crosslinking mechanism and pose interesting questions about the reactivity of benzoin derivatives in their excited states in relation to their efficiency in the crosslinking process.
Graft copolymers containing nucleic acid bases and L‐α‐amino acids
Authors: Overberger C. G. , Inaki Yoshiaki
Published: April 2003

Graft copolymers of nucleic acid bases and L‐α‐amino acids on polyethyleneimine were synthesized, and carboxyl derivatives of adenine and thymine were grafted by the p‐nitrophenyl ester method onto linear and branched polyethyleneimine. The carboxyl derivatives of nucleic acid bases were also grafted onto the monomeric graft copolymers of L‐α‐amino acids on polyethyleneimine; the carboxyl derivatives were obtained by the condensation of polyethyleneimine with L‐α‐amino acids with a coupling agent.
Radiation‐induced copolymerization of methyl trifluoroacrylate with propylene
Authors: Matsuda Osamu , Watanabe Terutaka , Tabata Yoneho , Machi Sueo
Published: April 2003

Copolymerization of methyl trifluoroacrylate (MTFA) with propylene in bulk was induced by γ irradiation. A wide range of the initial monomer composition gives an equimolar alternating co‐polymer. The reactivity ratios of r1 (MTFA) and r2 (propylene) were determined to be 0.01 and 0.005, respectively. The polymerization rate at an equimolar monomer composition is proportional to the 1.0 power of the dose rate. The dose rate dependency of higher than 0.5 may be ascribed to unimolecular termination due to a degradative chain transfer of propagating radicals to propylene. The G values of the initiating radical formation and the polymerization reaction were calculated to be 1.78 and 1336, respectively. The dependence of the copolymerization rate on the temperature was small, and the activation energy of copolymerization was 1.1 kcal/mole from −6 to 50°C.
Poly(β‐Amino acids). V. Synthesis and conformation of oligomeric α‐isobutyl‐L‐aspartate
Authors: Yuki Heimei , Okamoto Yoshio , Doi Yuichi
Published: April 2003

α‐Isobutyl‐L‐aspartate oligomers, Z‐(α‐i‐Bu‐Asp)2n–OEt (n = 1–5), where Z = benzyloxycarbonyl and OEt = ethyl ester, were prepared stepwise, and their conformation in solution was investigated by optical rotation, circular dichroism (CD), and NMR spectroscopy. The oligomers up to hexamer existed only in a disordered form. An ordered structure began to appear at octamer and decamer in chloroform and 2,2,2‐trifluoroethanol. The ordered structure was more favorable for N‐unprotected oligomers, H‐(α‐i‐Bu‐Asp)2n–OEt, in comparison with the corresponding Z‐(α‐i‐Bu‐Asp)2n–OEt. The effects of oligomer concentration and temperature on the structure were slightly observed. The most likely ordered structure was a β form caused by intramolecular association.
Higher aliphatic aldehyde polymers. VI. Poly(n‐nonaldehyde)
Authors: Starr J. , Vogl O.
Published: April 2003

Crystalline poly(n‐nonaldehyde) (PNA) was prepared by anionic polymerization of n‐nonaldehyde (NA) in methylcyclohexane (MCH) with lithium tertiary butoxide (LTB) as the initiator. Normal low‐temperature conditions did not give polymer reprodusibly; however, when the polymerization was carried out with a gradual temperature decrease to −60°C holding at this temperature followed by completion at −78°C, a moderate yield of PNA was obtained. The polymer was acetate capped and characterized. Infrared and PMR spectroscopy, as well as degradation of the polymer in the presence of 2,4‐dinitrophenylhydrazine to the hydrazone, conclusively proved the chemical structure of the polymer. VPO measurements and measurement of the inherent viscosity showed the polymer to be of moderate molecular weight. PNA is highly crystalline and shows two transition regions, one corresponding to the melting of the main chain at temperatures above 120°C and one region between 50 and 80°C, which is related to the crystallization of the aliphatic side chains. PNA, although inherently brittle, can be extruded through an orifice at a temperature near the side‐chain melting temperature to give an extrudate whose x‐ray patterns show the characteristics of a fiber diagram. It is suggested that the crystal structure of the PNA is similar to that of poly(n‐heptaldehyde) but with a larger a spacing, which is expected from a longer aliphatic side chain.
The stereoregularity of polystyrenes obtained by different ion pairs of polystyryl alkali salts
Authors: Uryu Toshiyuki , Kawamura Tokiji , Matsuzaki Kei
Published: April 2003

The stereoregularity of polystyrenes obtained with sodium, potassium, rubidium, and cesium naphthalenes in various solvents was determined by 13C‐NMR spectroscopy. Polystyrenes produced by contact ion pairs of polystyryl cesium in dioxane and tetrahydrofuran (THF) had the proportions of a 57–58% racemic dyad (Pr), whereas the Pr values increased to 65 and 69% by solvating Cs+ counterions in dimethoxyethane and by agent‐separating them with crown ether, respectively. Polystyrene obtained by contact ion pairs of polystyryl sodium in dioxane showed a Pr of 66%; polymers produced by solvent‐separated ion pairs of polystyryl sodium in THF at −78°C had a Pr of 71%. A polymerization system which contained alkali counterions with large ionic radii and solvents with low dielectric constants in which only contact ion pairs existed produced polystyrenes with isotactic‐rich configurations. The stereoregularity of polystyrene produced by contact ion pairs of polystyryl potassium and rubidium in tetrahydropyran (THP) occurred intermediately between that of polymers obtained in diethyl ether and THF. It was concluded that the stereoregulation of contact ion pairs may be closely related to the interionic distance of the ion pair.
Modification of properties of ion exchange membranes. VII. Relative transport number between various cations of cation exchange membrane having cationic polyelectrolyte layer and mechanism of selective permeation of particular cations
Authors: Sata Toshikatsu , Yamane Reiichi , Mizutani Yukio
Published: April 2003

Electrodialytic behavior of cation exchange membrane having cationic polyelectrolyte layer on its surface (relative transport number between two cations, P, current efficiency, and electric resistance of the membrane during the electrodialysis) was measured using various cations, and the mechanism of selective permeation of lower‐valent cations than the higher and of larger hydrated cations than the smaller was investigated. The following conclusions were obtained: (1) the cationic polyelectrolyte layer narrowed the pathway for ions; (2) when the pathway was made narrower by other methods, the remarkable change of the permselectivity of the membrane did not occur; (3) the effectiveness of the cationic polyelectrolyte layer was depressed by the treatment with anionic polyelectrolytes to neutralize the cationic charge on the membrane surface; and (4) the cation with larger hydrated diameter (potassium ions) more easily permeated through the membrane having the polyelectrolyte layer than that with the smaller hydrated diameter (sodium ions). It is concluded that the change of P by the cationic charge layer on the membrane surface is based on the difference in the strength of the electrostatic repulsion between two cations against the cationic charge layer.
Changes in row structure of extruded polyethylene film on grafting with styrene. I. Distribution of polystyrene and crystalline reorientation
Authors: Ungar G.
Published: April 2003

Extruded films of linear polyethylene were grafted with styrene in a 1:2 styrene‐‐‐methanol solution and pure styrene. The reaction was induced by simultaneous γ irradiation. Crystallinity of polyethylene was hardly affected by a polystyrene‐to‐polyethylene ratio as high as 13.5. From the anisotropy of film growth and small‐angle x‐ray diffraction it was concluded that polystyrene incorporated both into intercrystalline layers and newly formed domains alongside the stacks of lamellae. The proportion of polystyrene in interlamellar layers depends on the length of grafted chains; that is, on grafting conditions. A higher than expected proportion of occluded homopolystyrene was found in films grafted in methanol solution. The glass transition temperature of polystyrene decreased with grafting yield. Grafting in methanol solution produced changes in the x‐ray orientation pattern of polyethylene. This was ascribed to untwisting and straightening crystalline lamellae in the row nucleated cylindrites.
Copolymerization of carbon dioxide and propylene oxide with supported diethylzinc catalysts
Authors: Soga Kazuo , Hyakkoku Kyoko , Ikeda Sakuji
Published: April 2003

Diethylzinc was allowed to react with various metal oxides in n‐heptane at 60°C, and the copolymerization of propylene oxide and carbon dioxide was investigated at 60°C in solution in dioxane with reaction products as catalysts. An alternate copolymer was obtained with every catalyst, but the yield of copolymer and the number‐average molecular weight depended significantly on the supporting materials. In a kinetic study of the copolymerization we found that the catalytic efficiency (number of propagating species per number of zinc supported) was only a few percent with every catalyst. The copolymerization was also examined by using several kinds of silica, whose pore diameters are markedly different, as supports. The results obtained strongly suggested that only the active species existing in large pores act as the propagating species.
Molecular weight of polystyrene polymer obtained in the emulsion polymerization at low monomer concentration and the harkins–smith–ewart–gardon (HSEG) theory
Authors: Chatterjee Shankar P. , Banerjee Monoranjan , Konar Ranajit S.
Published: April 2003

The shape of the yield–time curves in the emulsion polymerization of styrene is a function of the recipe composition. Three types of yield–time curve were observed: (1) sigmoidal, (2) linear from the onset of polymerization, and (3) concave to the time axis; that is, the rate falls off continuously from the outset of polymerization. The viscosity‐average molecular weights (M̄v) of the polymers in a given run are approximately parallel to the average rate of polymerization [i.e.,(yield of polymer at time t)/(time t)]. The Harkin–Smith–Ewart–Gardon (HSEG) theory provides a qualitative description of the emulsion polymerization of styrene at low monomer concentration if the yield–time curve is sigmoidal. From Gardon's equations it is found that the average number of radicals per particle (Q) varies from 0.5 to 2.0, depending on the composition of the recipe. The (M̄v)expt/(M̄v)calc ratio lies between 1 and 2. The termination/propagation rate constant (kt/kp) ratio is a function of the composition of the recipe at a given temperature of polymerization and varies from 0.78 to 11.5 when it is estimated from the experimental data. The theoretical value, however, is 117.0. It has been shown that for a polydisperse system with particles of radius (r) between 10 and 1000 Å the maximum number of latex particles (N1)/ml of the aqueous phase would be 1019–1013; that is, if 10 ≤ r ≤ 1000 Å, then 5.97 × 1019 ≥ N1 ≥ 5.97 × 1013/ml.
The crystallization characteristics of ethylene block copolymers
Authors: Hay James N. , Wiles M.
Published: April 2003

Block copolymers of ethylene and butadiene with short ethylene sequences and degrees of polymerization up to 250 have been studied calorimetrically to determine their structure in the melt and also on crystallization. Crystallization rate characteristics and the thermodynamic parameters of the melting of block copolymers were studied. Block copolymers with ethylene sequences with degrees of polymerization below 20–30 were amorphous. Those with ethylene sequences of 35–45 units crystallized with extended chain crystals; above 45 units the polyethylene blocks crystallized with chain folding. There was a corresponding reduction in the melting point of the crystals and in the surface free energy of the crystals. The extent of crystallinity that developed within the copolymers was dependent on crystallization temperature and independent of time. This behavior was unlike that exhibited by polyethylene samples of similar molecular weight and was considered due to the effect of phase separation of the two blocks in the melt and nucleation control of the crystallization of the isolated domains. Analogous behavior was observed with polyethylene for polymer blends with polystyrene.
Effect of catalysts on asymmetric induction cationic copolymerization of l‐menthyl vinyl ether with indene
Authors: Kurokawa Masahiro , Yamaguchi Hidemasa , Minoura Yuji
Published: April 2003

Cationic copolymerization of l‐menthyl vinyl ether (l‐MVE) with indene (IN) was carried out with several catalysts in toluene (Tol) at 0°C. The catalysts used were BF3OEt2, CH3COClO4, and SnCl4. l‐Menthyl residue, an optically active side chain of the copolymer obtained, was removed with dry hydrogen bromide gas by the ether cleavage reaction. Ether‐cloven copolymers [vinyl alcohol(VA)–IN] also had optical rotation. The efficiency of asymmetric induction to the polymer main chain was in the order of BF3OEt2 > CH3COClO4 > SnCl4.
The effect of solvents on asymmetric induction cationic copolymerization of l‐menthyl vinyl ether with indene
Authors: Kurokawa Masahiro , Yamaguchi Hidemasa , Minoura Yuji
Published: April 2003

Cationic copolymerization of l‐menthyl vinyl ether (l‐MVE) with indene (IN) was carried out in several solvents with BF3OEt2 as catalyst at 0°C. The solvents used in this study were selected toluene (Tol), chloroform (CHCl3), chlorobenzene (BzCl), 1,2‐dichloroethane (EtCl2), and nitrobenzene; (BzNO2)/Tol = 65/35 mixture solvent. l‐Methyl residue, which is an optically active side chain of copolymer produced by cationic copolymerization, was removed with dry hydrogen bromide gas by ether cleavage reaction. The copolymer [vinyl alcohol(VA)–lN], produced by the ether cleavage reaction, also showed optical rotation. From this result, therefore, it was concluded that asymmetric induction takes place in the copolymer main chain. The efficiency of asymmetric induction was determined by the measurement of optical rotation of VA–IN copolymer after the ether cleavage reaction. The efficiency of asymmetric induction in the copolymer main chain developed from the variation on polymerization solvents; the order was Tol > EtCl2 > BzCl > CHCl3 > BzNO2/Tol (65/35) mixture solvent.
Block copolymers of copolyamides with polyoxirane
Authors: Masař B. , Čefelín P. , Šebenda J.
Published: April 2003

1,n‐Diaminopolyamides, based on lactams (P1), gave by reaction with isocyanate‐group‐terminated polyoxirane macromers (P2) in solution at ambient temperature, the copolymers of (P1 – P2)y type with y = 5–10 and solution viscosity ηred = 1–11 dl/g in high yields. The composition of copolymers (40–80% of P1) was found by elemental analysis and confirmed by the 1H‐NMR method. A substantial chain extension was observed in the reaction of macromers with low‐molecular‐weight “couplings.”
New processable polyaromatic ether‐keto‐sulfones curable by intramolecular cyclization. XV
Authors: Lin Shiow‐Ching , Marvel C. S.
Published: April 2003

New processable polyaromatic ether‐keto‐sulfones were prepared from 2,2′‐diiododiphenyl‐4,4′‐dicarbonyl dichloride (I), bis(p‐phenoxybenzene)sulfone (II), isophthaloyl chloride (III), and diphenyl ether (IV) in Friedel–Crafts‐type polymerizations. In the most promising of the iodine‐containing polymers phenylacetylenyl groups were introduced in place of iodine. This polymer, with an initial monomer ratio of I:II:III:IV = 1:5:7:3, was further investigated. It is soluble in DMF, DMA, pyridine, and sulfuric acid. After curing it was insoluble in all solvents used and lost only 1.1% of its weight at 300°C when heated in air for three days. Hence in this cured state it has excellent chemical and thermal resistance. It can be cast into a film from solution in DMAc and a glass fiber laminate is readily prepared. The film is tough, transparent, and brown in color. The cured film is tougher than the uncured. The glass fiber laminate is also tough and fairly flexible. A distinct advantage of this type of polymer is its ready availability in relatively cheap raw materials. The phenylacetylenyl‐group‐containing polymer showed a transition temperature at 175°C and two exotherm peaks at 243 and 361°C which disappeared after curing in a DSC thermogram. Before and after curing this polymer displayed softening temperatures at 149 and 171°C, respectively, measured by a Vicat apparatus at a heating rate of 1°C/min. No melting temperatures up to 500°C were observed for any of the polymers in this study.
Soluble and curable prepolymers from polyallyl ester monomers containing aromatic imide groups
Authors: Tamamura Toshiaki
Published: April 2003

Five polyallyl ester monomers that contain aromatic imide groups were synthesized as thermally stable laminating resins. From these monomers soluble and low‐melting prepolymers were obtained by radical polymerization in aprotic polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, or N‐methyl ‐2‐pyrrolidone. The prepolymers are oligomeric compounds in which DP = 3–6 and have lower melting points than the corresponding monomers. It is assumed that the reaction of solvent molecule participates in the polymerization. Whereas, the bulk and the solution polymerization in n‐butyl acetate or n‐propyl alcohol yielded insoluble and infusible polymer. The relatively low‐melting prepolymers were curable at 150–180°C without the evolution of volatile by‐products. Resulting glass‐fiber laminates have no glass transition point below 300°C and thermooxidative stability at 330°C.
Electron spin resonance study on polymerization of alkyl acrylates with n‐butyl titanate(IV)–triethylaluminum catalyst
Authors: Hiraki Katsuma , Ikeda Shigeru , Kaneko Shoichi , Hirai Hidefumi
Published: April 2003

n‐Butyl titanate(IV)–triethylaluminum catalyst at Al/Ti molar ratios greater than 6 polymerizes methyl and n‐butyl acrylates at −78°C. The polymerization system which includes methyl acrylate at −78°C, gives two ESR signals with g factors of 1.958 and 1.961 that overlap each other. The absorption intensity of the latter signal is approximately proportional to the polymer chain concentration calculated from polymer yield and the molecular weight. The polymerization system at Al/Ti ratios smaller than 3 has no catalytic activity on the polymerization and shows only the ESR signal with the g factor of 1.958. On the basis of these facts the ESR signal with the g factor of 1.961 is attributed to the active growing end of poly(methyl acrylate) with this catalyst. The character of this active growing end is discussed.
Direct polycondensation of nylon salts by polyphosphates and imidazole
Authors: Ogata Naoya , Sanui Kohei , Harada Masashi
Published: April 2003

Direct polycondensation of various nylon salts (salts of dicarboxylic acid and diamine) took place under mild conditions in the formation of polyamide in the presence of polyphosphates and organic bases. Among organic bases imidazole was the best in terms of polymer yields. The reactivity of the polyphosphates was arranged in following order: pyrophosphate ≅ tripolyphosphate > tetrapolyphosphate. Otimum reaction conditions were investigated in terms of solvents, temperatures, and concentration of monomers. A reaction mechanism was proposed for the phosphorylation reaction, due to polyphosphates, which led to the direct polycondensation of nylon salts.
Monomer‐isomerization oligomerization of 2‐ethyl‐1,3‐butadiene by acid catalysts
Authors: Higashimura Toshinobu , Hasegawa Hiroshi
Published: April 2003

The cationic oligomerization of 2‐ethyl‐1,3‐butadiene (2EBD) by a superacid (CF3SO3H) and a superacid derivative (CH3COClO4) accompanied monomer isomerization to 3‐methyl‐1,3‐pentadiene (3MPD) before propagation to yield oligomers of the isomerized monomer as main products in benzene at 50°C. Detection of 3MPD in the reaction mixture and 1H‐NMR structural analysis of the produced oligomers confirmed the occurrence of this “monomer‐isomerization oligomerization.” On the other hand, in the presence of a metal halide catalyst (BF3OEt2) 2EBD reacted without isomerization and yielded oligomers that were different from those produced by the foregoing superacid catalysts. Monomer isomerization was suppressed in a polar solvent [(CH2Cl)2] or at lower temperatures. The mechanism of the oligomerization with monomer isomerization was discussed.
Low‐molecular‐weight species from high‐pressure polyethylene
Authors: Von Dohlen W. C. , Wilson T. P.
Published: April 2003

A partial analysis is given of the low‐molecular‐weight “oil” fraction produced in the high‐pressure free‐radical–initiated polymerization of ethylene. These oils are shown to constitute a separate family of compounds whose molecular weight distribution can be clearly distinguished from that of the remainder of the polymer. The mechanisms of formation of oils as a class, and of individual compounds found in the oil fraction, are discussed in some detail. The structures of the oils are used to inter steps in the mechanism of polymerization that lead to the formation of short‐chain branches and unsaturation. It is concluded that the data are consistent with the extended Roedel mechanism with the provisions that (1) secondary radicals are probable products of radical scission, (2) cyclic intermediates of other than six members lead to the formation of three, five, and possibly six carbon branches, and (3) clusters of ethyl groups separated by single methylene groups are unlikely side chains.
Kinetics of imidization and crosslinking in PMR polyimide resin
Authors: Lauver Richard W.
Published: April 2003

Infrared spectroscopy and differential scanning calorimetry were used to study the imidization and crosslinking kinetics of norbornenyl‐capped addition type of polyimide resins (designated PMR for polymerization of monomer reactants). The spectral and thermal analyses were performed on resin specimens that had been isothermally aged at temperatures appropriate for imidization (120–204°C) and crosslinking (275–325°C). Imidization occurs rapidly (about 10−2 min−1) at short times, but, at times longer than about 0.5 hr, the rate decreases significantly (about 10−4 min−1). The crosslinking reaction exhibits first‐order kinetics during the initial part of the reaction, and its rate appears to be limited by the reversion of the norbornenyl Diels‐Alder adduct. Both the first‐order dependence and the activation energy (about 44 kcal) are consistent with this interpretation. The total heat evolved per mole of end cap during crosslinking shows an inverse dependence on the molecular weight of the imido prepolymers. This reflects the effect of end‐cap dilution and decreased mobility of the larger oligomers.
Synthesis of spiropolymers by polycycloaddition of ketene dimer with dinitrile oxides
Authors: Kurita Keisuke , Hirakawa Nobuhiko , Dobashi Toshiaki , Iwakura Yoshio
Published: April 2003

Novel spiropolymers containing biisoxazolinic units in the main chain were synthesized by polycycloaddition of ketene dimer with dinitrile oxides. Ketene dimer functioned as a difunctional monomer with loss of carbon dioxide, but use of 10% excess amount seemed to be the optimum condition in terms of viscosity of the resulting polymers. These spirocyclic polymers were white to pale yellow and had inherent viscosity of up to 0.34 dl/g. Thermogravimetric analysis of the polymers showed unusual abrupt reduction of weight at 279 or 298°C. Solubility was also studied.
Polylactide. II. Viscosity–molecular weight relationships and unperturbed chain dimensions
Authors: Schindler A. , Harper D.
Published: April 2003

Mark–Houwink equations for benzene and chloroform solutions of S‐polylactide and racemic polylactide were established by end‐group analysis of partly hydrolyzed polymers. Unperturbed chain dimensions calculated for both polymers reveal a considerable difference and suggest a helical conformation for S‐polylactide in solution. This finding supports 1H‐NMR observations that reveal chemical shift differences that appear when the same configurational sequence is present in two stable conformational states.
Interaction between dyes and polyelectrolytes. XI. Photoreduction of methylene blue bound to potassium polystyrenesulfonate
Authors: Shirai Masamitsu , Murakami Yoshihiro , Tanaka Makoto
Published: April 2003

The effect of potassium polystyrenesulfonate (PSSK) on the quantum yield (Φ) in the photoreduction of methylene blue (MB) by allylthiourea was investigated. MB was bound to PSSK in monomeric, dimeric, or slightly aggregated form, depending on the polyanion–dye ratio (P/D). At a relatively lower P/D in which most MB molecules were bound to PSSK in dimeric or slightly aggregated form, the value of Φ was smaller than that at a P/D of zero. On the other hand, at a higher P/D, in which most MB molecules were bound to PSSK in monomeric form, the value of Φ was larger than that at a P/D of zero. It was suggested that the lower reactivity of dimeric or slightly aggregated MB on PSSK was caused by the length of its lifetime which is shorter than that of the monomeric form. It was also suggested that the increase in Φ at higher P/D was caused by the decreased deactivation of the triplet excited MB by the ground‐state MB.
Synthesis of model molecules of functional isoprenic units
Authors: Clouet Françoise , Brossas Jean
Published: April 2003

We have prepared model molecules of monohydroxylic and monocarboxylic isoprenic units by initiating isoprene with sec.butyllithium in benzene and killing the living ends by oxygen or carbon dioxide; the monoadduct compounds have been isolated and characterized by nuclear magnetic resonance (NMR) and mass spectrometry.
Investigations on equilibrium of poly(ethylene oxalate) and 1,4‐dioxane‐2,3‐dione
Authors: Alksnis A. , Deme Dz.
Published: April 2003

Behavior of poly(ethylene oxalate) in a temperature range of 148–240°C was studied, and a new method of isolating 1,4‐dioxane‐2,3‐dione from the products of decomposition of poly(ethylene oxalate) was used. The process of decomposition was second order. Equilibrium of poly(ethylene oxalate) and 1,4‐dioxane‐2,3‐dione was registered at 148–240°C. The influence on this process of certain inorganic compounds as catalysts was investigated.
Functional monomers and polymers. LIII. Kinetic study on the oxidation of Cu(I)·polyvinylimidazole complexes by molecular oxygen
Authors: Sato M. , Kondo K. , Takemoto K.
Published: April 2003

The autoxidation of Cu(I) complexes with imidazole and polyvinylimidazole derivatives was studied by observing the formation of the corresponding Cu(II) complexes with a stopped‐flow technique. The reaction was second order and proportional to the concentrations of Cu(I) and oxygen. In the Cu(I)‐imidazole complex pH variation was without effect in the range of 7.5‐8.6. The oxidation rate of Cu(I).polyvinylimidazole complexes, on the other hand, decreased with a rise in pH. The activation parameters of the Cu(I)·polyvinylimidazole complexes, compared with those of the Cu(I).imidazole complex, were characterized by large enthalpic requirements coupled with favorable entropies of activation. This was explained by the fact that a conformational change in the polymeric ligands took place during oxidation.
Synthesis of polypyridazinophthalazinediones from diacetylphthalic acids and aromatic dihydrazines
Authors: Imai Yoshio , Ueda Mitsuru , Ohnuma Masakuni , Akashi Kuniaki
Published: April 2003

The cyclopolycondensation of two diacetylphthalic acids with aromatic dihydrazines produced a series of new high‐molecular‐weight polypyridazinophthalazinediones with pendant methyl groups. The polymers were best prepared in m‐cresol at 100°C and, after isolation, were readily soluble in dichloroacetic acid and m‐cresol. Clear yellow films could be cast from m‐cresol solutions and thermogravimetric analysis of all the polymers showed a 10% weight loss at 455–;505°C in nitrogen.
Effect of water on the glass transition temperature of poly(hydroxy methylene)
Authors: Reimschuessel H. K. , Turi E. A. , Akkapeddi M. K.
Published: April 2003

The effect of moisture on the glass transition temperature of poly(hydroxy methylene) was investigated by thermal analysis which entailed combinations of DTA and DSC with TGA techniques. As the moisture content increased, the glass transition temperature (Tg) decreased monotonically from a value (Tgo) of 134°C for the dry polymer toward a finite value (Tgt) of about 39°C. This response of Tg to an increase in the moisture content (w) was adequately represented by the general relationship Tg = (ΔTg)0 exp{–[ln(ΔTg)0]w/τwl} + Tgl, recently developed for correlating Tg and moisture content of nylon 6 and and found generally applicable to hydrophilic polymers. With (ΔTg)0 = 95, τ = 0.555, and wl = 0.375, good agreement was found between experimental and calculated values for poly(hydroxy methylene).
The effects of overall composition and monomer sequence distribution on the infrared carbonyl stretching frequencies of ethylene–vinylacetate and styrene–vinylacetate copolymers
Authors: Ebdon J. R. , Kandil S. H. , Morgan K. J.
Published: April 2003

The vinyl acetate centered triad fractions of some free radically prepared ethylene–vinyl acetate and styrene–vinyl acetate copolymers have been determined from the patterns of vinyl acetate methine carbon peaks in their 13C nuclear magnetic resonance (NMR) spectra. The positions and shapes of the carbonyl bands in the infrared (IR) absorption spectra of the copolymers recorded in chloroform are shown to depend on the compositions of the copolymers and on the proportions of the various vinyl acetate centered triads. Infrared absorption measurements may thus be used in part to characterize the monomer sequence distributions of these copolymers.
Preparation and photolysis of poly‐4′‐acetylacrylophenone and its copolymers with styrene and methyl methacrylate
Authors: Lukáč I. , Chmela Š. , Hrdlovič P.
Published: April 2003

Poly‐4′‐acetylacrylophenone (P4AcAP) and its copolymers with styrene (4AcAP/S) and methyl methacrylate (4AcAP/MMA) were prepared. Ultraviolet (UV) spectra of these polymers show an absorption band at 29,500 cm−1 (ϵ = 270) of n‐π* character. The low temperature emission spectra of films of copolymers studied exhibit a less resolved vibrational structure and are bathochromically shifted with respect to those of polyacrylophenone and its styrene and methyl methacrylate copolymers. The emission decay is slightly nonexponential and has a lifetime of about 0.02 sec. Quantum yields of main chain scission in solution with 366‐nm radiation are of the same order as those of the unsubstituted polyacrylophenone. Substitution by a strong electron‐accepting group, in comparison with polyacrylophenone, influences the value of the quantum yield only a little but prolongs the lifetime of the lowest triplet state. This is also evident in an increase in the Stern–Volmer constant in passing from polyacrylophenone–naphthalene in benzene (68 mole−1) to P4AcAP–naphthalene in dioxane (380 mole−1). With biphenyl as a triplet quencher, the Stern–Volmer constants are low because of back transfer:
Chemiluminescence study of PS–PVME compatible mixtures
Authors: Naito K. , Kwei T. K.
Published: April 2003

The oxidation of polystyrene (PS), poly(vinyl methyl ether) (PVME), and their mixtures has been studied by the chemiluminescence method. It was found that luminescence versus temperature curves had sharp inflections that shifted to higher temperatures with increasing PS content of the blends. A linear relationship was obtained between inflection temperatures and onsets of oxidation exotherms as measured by calorimetry. The inflection points for the mixtures also correlated linearly with the temperatures of thermally induced phase separation
Carboxylation of a polypentenamer and preparation of its hydrogenated derivatives
Authors: Tanaka H. , Macknight W. J.
Published: April 2003

Carboxylated three‐membered ring derivatives of a polypentenamer (PP) that contained 82% trans and 17% cis double bonds were prepared by carbene addition of ethyldiazoacetate with a copper catalyst to the double bonds and subsequent hydrogenation of the residual unsaturation. In this way derivatives that contained approximately either 5 or 10 mole % three‐membered rings with ester side groups were obtained. These side groups were further reacted by hydrolysis or neutralization to form carboxylic acid and cesium salts of carboxylic acid. Reaction conditions were chosen so that no backbone degradation occurred and side reactions that led to crosslinking were avoided. The derivatives were characterized by gel permeation chromatography (GPC), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. It was found that an increase in substituent concentration decreased the melting point (Tm) in hydrogenated derivatives and increased the glass transition temperature (Tg) in unhydrogenated derivatives. The cesium salts of carboxylic acid were the least thermally stable among those studied and the hydrogenated derivatives were generally more stable than the unhydrogenated.
Polyimidines. IV. The synthesis and polymerization of 3,3‐diphenyl‐6‐aminophthalide
Authors: Fawcett Newton C. , Lohr Raymond A. , Cassidy Patrick E.
Published: April 2003

The monomer 3,3‐diphenyl‐6‐aminophthalide was synthesized in a 20% yield by the following sequence of reactions: nitration of phthalimide, hydrolysis and dehydration to 4‐nitrophthalic anhydride, Friedel–Crafts reaction with benzene to 2‐benzoyl‐5‐nitrobenzoic acid, cyclization with thionyl chloride to the pseudoacid chloride, Friedel–Crafts reaction with benzene, and, finally, reduction of the nitro group to the amino function with Adams catalyst. Although the five‐substituted isomer is also possible, it was obtained in yields of only one‐fifth to one‐tenth of those for the 6‐substituted isomer. The 3,3‐diphenyl‐6‐aminophthalide underwent polymerization with difficulty to yield low‐molecular‐weight polyimidines (inherent viscosity up to 0.68 dl/g) in reasonable yields (32−88%). Because of the rigid character of the backbone and steric crowding, conditions for polymerization were rather severe: 1–2 days at 180–225°C in nitrobenzene or polyphosphoric acid or 350°C in a sealed tube. The addition of sand to the reactants in the sealed tubes caused an increase in yield and molecular weight. The polymers were subjected to thermogravimetric analysis in air and nitrogen. The temperatures at which a 10% weight loss occurred were as high as 440°C in air and 510°C in nitrogen. These stabilities were similar to those encountered for previously synthesized all‐aromatic polyimidines.
Particle nucleation in emulsion polymerization. II. Nucleation in emulsifier‐free systems investigated by seed polymerization
Authors: Hansen F. K. , Ugelstad J.
Published: April 2003

Experiments with seeded polymerization in emulsifier‐free systems were carried out with styrene in order to test the theory of particle nucleation presented in the first article in this series. The effect of amount, size, and surface charge density of the seed particles on the formation of new particles was investigated. An expression for the capture rate of oligomeric radicals from the water phase was evaluated in which the rate of capture was considered to be governed by the absorption of oligomers with chain length one less than the critical chain length for precipitation of the oligomer. Coagulation of primary particles was also included in the expression for the number of new particles obtained in the system. Limited coagulation of primary particles with already formed particles and with seed particles was found to play an important role in determining the final number of new particles found at the end of the runs.
Epoxy resins. III. Application of fourier transform IR to degradation studies of epoxy systems
Authors: Lin S. C. , Bulkin B. J. , Pearce E. M.
Published: April 2003

Three cured epoxy resins were investigated under various degradation conditions by Fourier transform infrared (FTIR) spectroscopy for measurement. The epoxy resins were the diglyadyl ethers of bisphenol A (DGEBA), phenolphthalein (DGEPP), and 9,9‐bis(4‐hydroxyphenyl)fluorene (DGEBF). The thermal stability order of functional groups that incurred DGEBA was total methyl group ∼ total benzene ring > methylene > p‐phenylene > ether linkage > isopropylidene. The oxidative thermal and photodegradation processes were found to be related to the classical autocatalytical oxidation of aliphatic hydrocarbon segments. The Wieland rearrangement, Norrish‐type reaction, Claisen rearrangement, and other possible degradation mechanisms were suggested by the data.
Syntheses of polyimide copolymers based on N,N′‐(pyromellitoyl)diglycine
Authors: Yang Chin‐Ping
Published: April 2003

N,N′‐(pyromellitoyl)diglycine (1) was synthesized by reacting pyromellitic anhydride with glycine in polar solvents such as DMAC, NMP, or DMF at 60°C and then refluxed azeotropically with toluene. Among these solvents, it is easy to form DMF‐insoluble salt (1″) in DMF, but this salt can be converted to 1 by treating first with NaHCO3 and then with HCl. Reacting monomer N,N′‐(pyromellitoyl)diaminoacetyl chloride (2) can be obtained by treating with thionyl chloride, and N,N′‐(pyromellitoyl)dimethyl aminoacetate (3) can be obtained by treating 2 with methanol. As 2 reacts with aromatic diamine in polar solvents, such as DMAC, DMF, or NMP, a series of copolypyromellitimide amides (5a–h) can be obtained. These copolymers can be processed by using DMAC + LiCl (5%) as solvent to produce flexible film of good weather resistivity and heat resistivity. Monomer 2 can also react with aromatic dihydrazides in polar solvents to produce copolypyromellitimide hydrazides (6a–c), and 6a–b can be condensated again to produce copolypyromellitimide oxadiazoles (7a–b) in polyphosphoric acid (PPA). Besides, 3 reacts with aromatic tetraamine by carrying out polycondensation in PPA to produce copolypyromellitimide benzimidazole (8). Structures of copolymers mentioned above were identified by comparing IR spectra with those of model compounds. Heat resistivity was measured by the thermogravimetric method, and their solubilities in various solvents were also investigated.
Asymmetric induction radical copolymerization of optically active l‐menthyl vinyl ether with vinylene carbonate and indene
Authors: Kurokawa Masahiro , Minoura Yuji
Published: April 2003

The copolymerizations of l‐menthyl vinyl ether (l‐MVE) with the monomers vinylene carbonate (VCA) and indene (IN) were carried out in benzene with azobisisobutyronitrile (AIBN) as an initiator to obtain optically active copolymers. The optically active l‐menthyl residue from the copolymer main chain was removed using dry hydrogen bromide gas. After the ether cleavage reaction, the copolymers prepared (VA–VCA and VA–IN) were still optically active, and hence it was found that asymmetric induction had taken place in the copolymer main chain. The optical rotatory dispersion (ORD) and circular dichroism (CD) data of the original and ether‐cloven copolymers were also determined.
Vapor‐phase graft copolymerization of binary solid monomers onto poly(ethylene‐co‐vinyl acetate) film by ultraviolet irradiation
Authors: Hayakawa Kiyoshi , Kawase Kaoru , Yamakita Hiromi
Published: April 2003

Vapor‐phase graft copolymerizations of acenaphthylene–maleimide or acenaphthylene–maleic anhydride binary solid monomers onto poly(ethylene‐co‐vinyl acetate) films were carried out under ultraviolet irradiation. The extent of sorption of single or binary monomers increased with the increasing vinyl acetate content in the backbone polymers. The sorbed binary monomers were mainly composed of acenaphthylene, but the maleimide or maleic anhydride fraction increased with the increasing vinyl acetate content of the films and the composition was little affected by surface hydrolysis. In all series of graft polymerization of single or binary monomers the overall extent of grafting increased with the vinyl acetate content and was suppressed by the surface hydrolysis of the backbone film. The composition of the grafted copolymer, however, differed markedly, depending on the combination of binary monomers. The grafted copolymer in the acenaphthylene–maleimide system was composed mainly of acenaphthylene units, whereas that in the acenaphthylene–maleic anhydride system was composed mainly of maleic anhydride units. The results were compared with those of γ‐ray grafting, and it was suggested that the contribution of a direct supply of monomers from vapor phase and the existence of an acetoxy group on the surface of the film should play an important role in the grafting reaction.
Synthesis and properties of optically active polyurea by interfacial polyaddition
Authors: Yasuzawa Takashi , Yamaguchi Hidemasa , Minoura Yuji
Published: April 2003

Optically active polyureas were prepared from optically active diisocyanate (L‐lysinediisocyanatemethylester) and optically inactive linear diamine [H2N(CH2)nNH2, n = 2,3,4,5,6, and 9]. Polymerization was carried out by the interfacial polyaddition technique using the benzene–water system and by solution polyaddition. The values of optical rotation of obtained polyureas were dependent on the methylene number of diamines. Asymmetric selective polyaddition of L‐lysinediisocyanatemethylester for racemic 1,2‐diaminopropane was unsuccessful.
Equilibrium study of polymer–polymer complexation of poly(methacrylic acid) and poly(acrylic acid) with complementary polymers through cooperative hydrogen bonding
Authors: Osada Yoshihito
Published: April 2003

The degree of linkage, θ, defined as the ratio of the binding groups to the total of potentially interacting groups and the stability constant K of the polymer–polymer complexes in the systems poly(methacrylic acid)–poly(ethylene glycol), poly(acrylic acid)–poly(ethylene glycol), and poly‐(methacrylic acid)–poly(vinyl pyrrolidone) in aqueous and aqueous alcohol media were determined as a function of temperature by potentiometric titration. It was found that θ and K are strongly dependent on chain length, temperature, and medium and that hydrophobic interaction is a significant factor in the stabilization of the complexes. The enthalpy and entropy changes and the cooperativeness parameter of the systems were calculated. A mechanism for the complexation in terms of cooperative interaction was proposed.
The preparation of α‐substituted acrylic esters
Authors: Ponticello I. S.
Published: April 2003

Treatment of the lithium enolates of cyclopentadiene‐blocked acrylates with various electrophilic reagents, such as alkyl chloroformates, α,β‐unsaturated carbonyl compounds, epoxides, episulfides, and α‐halocarbonyl compounds, has led to a convenient synthetic method for the preparation of α‐substituted acrylic esters.
Polysiloxane zwitterionomers and related model compounds. I. Synthesis
Authors: Graiver D. , Baer E. , Litt M. , Baney R. H.
Published: April 2003

Polymers containing zwitterions were prepared by reacting γ‐propanesultone with polydimethylsiloxane‐co‐(4,7‐diazaheptylmethylsiloxane), which generated substituted di(ammonium‐3‐propane‐sulfonate) groups pendant from the siloxane chain. Their concentration in the polymers varied from 0.5 to 10 mole %. Two model compounds were also prepared in order to (1) characterize the reaction leading to the formation of these zwitterions and (2) characterize the ionic forces in solutions (tetrahydrofuran and benzene were used as solvents). The degree of aggregation of these model compounds was higher in tetrahydrofuran and increased in both solutions with the concentration. No rearrangements of siloxane bonds were observed in the presence of these zwitterions or γ‐propanesultone.