bluuebunny/crossref_metadata_2025 huggingface dataset:
Aromatic polyamides. III. Copoly(4,4′‐oxanilideterephthalamide—4,4′‐phenyleneterephthalamide): Synthesis, wet‐spinning, fiber thermal characterization, and stability in sulfuric acid
Authors: Silver Frank M. , Dobinson Frank , Ridgway James S.
Published: April 2003

Copoly(4,4′‐oxanilideterephthalamide—4,4′‐phenyleneterephthalamide) (A‐202/PPD) was synthesized by reaction of 4,4′‐diaminooxanilide, p‐phenylenediamine, and terephthaloyl chloride in organic solvents. Copolymer inherent viscosities in H2SO4 as high as 10.3 were obtained. Isotropic copolymer solutions (4%—5% concentration) of A‐202/40%–80% PPD were spun to fibers with tenacity/elongation/modulus at 1% extension in the 13–14 gpd/1.5%–2%/700–1000 gpd range. Oxamide and amide stabilities in 98–100% H2SO4 and 20% oleum were compared. Poly(4,4′‐oxanilideterephthalamide) (A‐202), A‐202/PPD copolymers, and poly(4,4′‐phenyleneterephthalamide) (PPT) were unstable in 20% oleum, but all proved relatively stable in 100% H2SO4. However, the oxamide linkage proved less stable than the amide linkage in 98% H2SO4. A‐202 and A‐202/PPD copolymers formed stable anisotropic spinning solutions in 1% oleum at 10–20% concentrations. Dynamic mechanical analyses (Vibron) showed no glass transition temperature (Tg) below 200°C. Dilatometric measurement of A‐202/50% PPD revealed a Tg at 257°C. Differential thermal analyses of A‐202/40–80% PPD exhibited endotherms at 470–480°C. Thermogravimetric analyses showed no significant weight loss below 400°C.
Polymerization of isoprene initiated by the reaction products of η3‐allyl complexes of transition metals and titanium chlorides
Authors: Vasiliev V. A. , Sokoryanskaya T. I. , Kormer V. A.
Published: April 2003

The main path of the interaction of chromium and nickel η3‐allyl complexes and titanium tetrachloride is the transfer of allyl ligands to titanium with the concomitant reduction of TiCl4 to η‐TiCl3 and the formation of the products initiating isoprene polymerization. The stereospecific effect of the system is because of the formation of bimetallic complexes with bridged metal—carbon bonds which are the most probable centers of stereospecific cis‐1,4‐polyisoprene chain propagation.
Thermal degradation of mixtures of poly(methyl methacrylate) and silver acetate
Authors: Jamieson A. , McNeill I. C.
Published: April 2003

The degradation behavior of silver acetate—PMMA blends at salt/polymer ratios of 1:1, 1:5, and 1:10 has been studied by using thermal volatilization analysis (TVA) as the principal technique. Degradation of the salt has also been examined; it gives a variety of products best explained by a series of reactions resulting from an initial cleavage of CH3COO. radicals and silver atoms. Silver acetate, when present with PMMA during degradation, results in a severe destabilization of the polymer, which breaks down to monomer at a high rate at temperatures as low as 200°C. This effect is explained by diffusion of radicals from silver acetate decomposition into the polymer phase, in which they initiate chain scission and depolymerization.
Redetermination of the crystal structure of calcium acrylate dihydrate at 183 K
Authors: Page Yvon Le , Fortier Suzanne , Donnay Gabrielle
Published: April 2003

The crystal structure of (CH2CHCO2)2Ca.2H2O is different from that reported in the literature. Single‐crystal intensities were collected at 183 ± 5 K and the structure was refined with 564 trustworthy reflections to a residual of 6.6% in space group P21/a. Cell dimensions are a = 14.11(2), b = 6.63(1), c = 11.76(2)Å, and β = 118.4(1)°, Z = 4. The structure consists of dimolecular layers 10 Å thick, parallel to (001) and joined by van der Waals attractions. Each layer contains two sheets of acrylate groups on its outside borders that point toward a central sheet of eight‐coordinated calcium ions and hydrogen‐bonded water molecules. One of the two symmetry‐independent acrylate groups is planar; the other deviates significantly from planarity. Calcium ions surround the nonplanar molecule in a lopsided fashion.
Low‐molecular‐weight polybenzimidazoles from aromatic dinitriles and aromatic diamines
Authors: Brand Richard A. , Bruma Maria , Kellman Raymond , Marvel C. S.
Published: April 2003

Three oligomeric benzimidazoles have been prepared by the oxidative cyclization of the corresponding polyamidines. These materials are high melting and are soluble in solvents like dimethylformamide. They exhibit inherent viscosities of 0.20–0.25 in DMF at 0.5g/100 ml. Several model compounds have also been prepared to show the feasibility and scope of the oxidative cyclization reaction.
Sorption of ethanesulfonic acid by nylon‐6 containing various numbers of end groups
Authors: Obara T. , Iijima T. , Komiyama J. , Ikeda S. , Ishikawa H. , Nakagawa T.
Published: April 2003

From the analysis of the permeation of 35S labeled ethanesulfonic acid, through nylon‐6 films sorption isotherms were obtained. The films are characterized by their largely different content of carboxyl and amino end groups. It was found that the shape of the isotherm depends on the molar ratio of the two end groups: an S‐shape curve for the film containing the carboxyl end group larger than the amino end group and a Langmuir‐type curve for the film containing comparable numbers of end groups. These results were explained by the McGregor‐Harris theory in which the acid dissociation constants of the two end groups in nylon were estimated experimentally.
Interaction between dyes and polyelectrolytes. X. Excitation energy transfer in cationic dye–polyanion system
Authors: Shirai Masamitsu , Nagatsuka Tatsuki , Tanaka Makoto
Published: April 2003

The quantum yield for the trypaflavine‐photosensitized oxidation of 1‐(methylthio)ethyl‐3‐carbamoylpyridinium chloride to 1‐(methylsulfinyl)ethyl‐3‐carbamoylpyridinium chloride increased with increase in the concentration of methylene blue added. It was inferred that the increase in the quantum yield is due to the excitation energy transfer from trypaflavine to methylene blue. The efficiency of excitation energy transfer was enhanced on addition of potassium poly(vinyl sulfate) and was dependent on the polyanion/dye ratio. The efficiency of excitation energy transfer at the most appropriate polyanion/dye ratio was about 5 times as high than that in the absence of polyanion. The binding of dye to potassium poly(vinyl sulfate) was investigated spectrophotometrically. Correlation with the dye binding to potassium poly(vinyl sulfate) and the efficiency of excitation energy transfer between dyes was discussed.
Dye‐sensitized photoinitiated cationic polymerization
Authors: Crivello J. V. , Lam J. H. W.
Published: April 2003

Several dyes have been discovered which sensitize the photolysis of diaryliodonium salts at visible wavelengths. By using the combination of a dye and a diaryliodonium salt, visible light can be used to photoinitiate cationic polymerization. In this article, the dye‐sensitized photopolymerizations of cyclohexene oxide, epichlorohydrin, and 2‐chloroethyl vinyl ether are described.
Reactivity of cobaloxime bound to polystyrene chain by carbon–cobalt σ bond
Authors: Nishikawa Hiroshi , Terada Ei‐Ichi , Tsuchida Eishun , Kurimura Yoshimi
Published: April 2003

The (alkyl)‐bis(dimethylglyoximato)pyridinecobalt attached to polychloromethylstyrene by a cobalt–carbon bond was prepared by the reaction of Co(II)(DH)2Py with polychloromethylstyrene in benzene. The fraction of p‐vinylbenzyl·Co(DH)2Py introduced to the polymer was 8.1 and 2.1 mole %. The photodecomposition of the polymer‐bonded cobaloxime was investigated by following the change of the visible spectrum. The rate constant kdec of the polymer‐bonded cobaloxime was 1.1 × 10−2 sec−1 in benzene; it is one‐fourth of that of its monomeric analog, benzyl·Co(DH)2Py. The kdec values of the cobaloximes were also measured in benzene–dimethyl sulfoxide mixed solvents, and the polymer effects were discussed. The dependence of the photodecomposition on energy of the irradiation light was investigated, and it was found that the absorption band near 470 nm is important for the photodecomposition of the cobalt–carbon bond. Spectroscopic measurements of the ligand exchange reaction of polymer‐bonded cobaloxime with pyridine in dimethyl sulfoxide gave a larger equilibrium constant (1.2 × 104 liter/mole) than that of benzyl·Co(DH)2Py (9.4 × 102 liter/mole). The kinetic data of the ligand exchange reaction indicated that the larger equilibrium constant for the polymeric system is due to the smaller rate constant of the reverse reaction. The thermodynamic parameters were also obtained.
Unequivocal synthesis of bis(2‐cyanoacrylate) monomers. I. Via anthracene adducts
Authors: Buck Carl J.
Published: April 2003

An unequivocal and general synthesis of bis(2‐cyanoacrylate) monomers from Diels‐Alder adducts of the alkyl 2‐cyanoacrylates has been developed. Saponification of the anthracene adduct of either isobutyl or ethyl 2‐cyanoacrylate to the anthracene/2‐cyanoacrylic acid adduct, conversion of the latter to the alkali salt or acid chloride derivatives, followed by respective esterification reactions with an organic dihalide or glycol gave the bis‐anthracene adduct precursors to the bis(2‐cyanoacrylate) monomers. Heating the bis‐adducts with excess maleic anhydride in refluxing xylene effected retrograde diene scission to the bis(2‐cyanoacrylate) monomers in up to 80% overall yields. Comonomer blends of the difunctional bis(2‐cyanoacrylates) with the alkyl 2‐cyanoacrylates gave crosslinked polymeric adhesive compositions exhibiting higher bond strengths under both dry and wet conditions than the noncrosslinked cyanoacrylate adhesives. Potential applications of interest are as pit and fissure sealants in dentistry and for the direct bonding of orthodontic attachments.
Preparation and degradation of head‐to‐head PVC
Authors: Crawley S. , McNeill I. C.
Published: April 2003

The course of the chlorination reaction of cis‐1,4‐polybutadiene is dependent on the choice of solvent. When methylene chloride is used, a pure addition reaction of chlorine leads to a polymer with the structure of head‐to‐head, tail‐to‐tail PVC. The thermal stability of the head‐to‐head PVC polymer has been studied by thermal volatilization analysis, thermogravimetry, and evolved gas analysis for hydrogen chloride, and the changes in the ultraviolet (UV) spectrum of the polymer during degradation have been investigated. The head‐to‐head polymer has a lower threshold temperature of degradation than normal PVC, but reaches its maximum rate of degradation at a higher temperature for powder samples of the polymer under programmed heating conditions. Blends of head‐to‐head PVC with poly(methyl methacrylate) have also been degraded, and the presence of the head‐to‐head polymers, like that of normal PVC, results in depolymerization of the PMMA as soon as the dehydrochlorination reaction commences. The mechanism of degradation of head‐to‐head PVC is discussed.
Viscoelasticity of rubber‐resin mixtures
Authors: Aubrey D. W. , Sherriff M.
Published: April 2003

The dynamic viscoelastic response of blends in various proportions of natural rubber with each of two tackifier resins, a poly(β‐pinene) and a pentaerythritol ester of hydrogenated rosin, has been investigated. Results are presented in the form of master curves of the modulus G′r and the viscosity η′r against frequency. The two resins show remarkably similar behavior in modifying the viscoelastic behavior of the rubber; the most obvious effects of increasing resin concentration are (a) a displacement of the transition zone toward lower frequencies, (b) a reduction in width and eventual elimination of the “rubbery plateau,” and (c) a displacement of the terminal zone in the direction of higher frequencies. The effect (a) is interpreted in molecular terms as a restriction of segmental motion and may be quantitatively evaluated in terms of reduced fractional free volume and increased monomeric friction coefficient. Effects (b) and (c) are explicable in terms of reduced average molecular weight, with consequent reduction in entanglement coupling and resistance to viscous flow. Quantitative analysis of the results, using relaxation time spectra, lends support to the iso‐free‐volume theory of the glassy state and shows a correlation between fractional free volume and monomeric friction coefficient.
Radiation‐induced polymerization of glass‐forming systems. VII. Polymerization in supercooled state under high pressure
Authors: Kaetsu Isao , Yoshii Fumio , Watanabe Yuhei
Published: April 2003

Radiation‐induced polymerization of glass‐forming monomers such as 2‐hydroxyethyl methacrylate and glycidyl methacrylate under high pressure was studied. The glass transition temperature of these monomers was heightened by increased pressure. The temperature dependence of polymerizability showed a characteristic relation; similar to those in supercooled‐phase polymerization under normal pressure, that had a maximum at Tv which shifted to higher levels of temperature as well as to Tg under high pressure. Polymerizability in the supercooled state also increased under increased pressure.
CIDNP studies of macromolecular systems. I. Photolysis of poly(methyl isopropenyl ketone) and its model compounds in solution
Authors: Bargon Joachim
Published: April 2003

The photoreactions of poly(methyl isopropenyl ketone) (PMIK) and two low‐molecular‐weight model compounds have been investigated in solution with proton NMR spectroscopy. Chemically induced dynamic nuclear polarization (CIDNP) has been observed in all three systems, but the CIDNP intensities have been found to depend on the chain lengths of the reaction products: long‐chain products fail to show CIDNP at room temperature, whereas simultaneously formed small fragments exhibit nuclear spin polarization. The CIDNP originates from the Norrish type I decomposition of the ketones, which for the polymer occurs from the triplet state in all solvents. In the model compounds this cleavage can occur from the triplet or singlet state. The main photoreaction of PMIK, namely, scission of the polymer backbone, does not give rise to CIDNP. The failure of long‐chain products to display CIDNP is attributed in part to a relaxation phenomenon: the short nuclear spin relaxation times of the long‐chain product molecules destroy the CIDNP before it can be detected. In high‐temperature studies above 150°C, however, in which the relaxation times are longer, CIDNP has been detected in long‐chain molecules as well.
Modification of cellulose phosphonate with N,N‐dimethylacrylamide and 4‐vinylpyridine, and flame‐retardant properties of the products
Authors: Inagaki Norihiro , Katsuura Kakuji
Published: April 2003

Cellulose phosphonate was added to N,N‐dimethylacrylamide (A) and 4‐vinylpyridine (B) in the presence of sodium ethoxide to yield cellulose 2‐(N,N‐dimethyl)carbamoylethylphosphonate and cellulose 2‐pyridinylethylphosphonate, respectively. The extent of the addition was 50% for (A) and 10% for (B), based on P—H bonds in cellulose phosphonate. The modification of cellulose with (A) resulted in an increase in the threshold temperature for weight loss, a decrease in the amount of residual products, and retardation of deammoniation of ammonium salts of the products. Modification of (B) resulted in a lower threshold temperature and amount of residue and an acceleration of the oxidation of cellulose chains. Cellulose phosphonate fabrics modified with (A) had powerful flame‐retardant properties. It was deduced that the combination of phosphoryl and amide groups was an effectual flame retardant.
Synthesis of polyenamines by vinylogous nucleophilic substitution polymerization of 1,6‐diethoxy‐1,5‐hexadiene‐3,4‐dione with diamines
Authors: Ueda Mitsuru , Otaira Kouetsu , Imai Yoshio
Published: April 2003

Novel polyenamines with inherent viscosities in the 0.2–1.1 range were synthesized by the vinylogous, nucleophilic substitution polymerization of 1,6‐diethoxy‐1,5‐hexadiene‐3,4‐dione with aromatic and aliphatic diamines in polar aprotic solvents at room temperature. The most effective polymerization medium was hexamethylphosphoramide for preparing high‐molecular‐weight polymers from aromatic diamines. The dilute solutions showed a marked decrease in viscosity with time. The aromatic polyenamines began to lose weight around 200°C under thermogravimetric analysis in air and nitrogen.
Synthesis of novel fluorocarbon ether bibenzoxazole polymers
Authors: Evers Robert C.
Published: April 2003

Novel fluorocarbon bis(o‐aminophenol) monomers were synthesized by a multistep route from 1,3‐diiodohexafluoropropane and 1,8‐diiodohexadecafluorooctane. The acetic acid‐promoted polycondensation of these monomers with fluorocarbon ether‐diimidate esters led to linear, soluble fluorocarbon ether‐bibenzoxazole polymers with inherent viscosities in the range of 0.10–0.94 dl/g−1. Polymer structures were verified by elemental and infrared (IR) spectral analysis. Many of the polymers exhibited considerable crystallinity in which the crystalline melt temperatures ranged from 53 to 187°C, as determined by differential scanning calorimetry. Some polymers, however, were isolated as completely amorphous, rubbery gums that exhibited glass transition temperatures as low as −31°C. Good thermooxidative stabilities were exhibited with onset of weight loss of the polymers during thermogravimetric analysis in an air atmosphere occurring in the 375–450°C range.
Diol sequencing in copolyesters
Authors: Mackey John H. , Pattison V. A. , Pawlak J. A.
Published: April 2003

Homogeneous condensation of a symmetrical diacyl monomer T with two symmetrical diols D1 and D2 has been studied under low‐temperature, nonequilibrium conditions, using the diol sequence in the product as a probe. For terephthalate copolyesters of diols such as bisphenol A and neopentyl glycol the alternation frequency f12 has been related to the rate parameters by measurement [using nuclear magnetic resonance (NMR) and other methods] and calculation.

It is usually assumed that all functionalities attached to the same residue have the same reactivity, that is, that all steps of type

have the same specific rate; this assumption leads to a random, high‐molecular‐weight copolyester. If the diacyl species shows a large penultimate group effect, as in phosgene, chloroformate [see M. Matzner et al., Chem. Rev., 64, 645 (1964)], and phthalates, this assumption must be discarded.

After simplification the alternation can be calculated exactly in terms of two parameters: r, the relative reactivity of the diacyl functionalities, and δ, the relative reactivity of the two diols. A nonrandom copolyester results only when neither r nor δ is unity. The maximum nonrandomness (for fixed r) occurs when δ → ∞ (sequential reaction).
Emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. I. Effects of reaction conditions on the polymerization rate and polymer molecular weight
Authors: Suwa Takeshi , Watanabe Terutaka , Okamoto Jiro , Machi Sueo
Published: April 2003

The radiation‐induced emulsifier‐free emulsion polymerization of tetrafluoroethylene was carried out at an initial pressure of 2–25 kg/cm2, temperature of 30–110°C, and under a dose rate of 0.57 × 104−3.0 × 104 rad/hr. The rate of polymerization was shown to be proportional to 1.0 and 1.3 powers of the dose rate and initial pressure, respectively, and is maximal at about 70°C. The molecular weight of polytetrafluoroethylene (PTFE) lies in the range of 105−106, increases with reaction time in the early stage of polymerization, and is maximal at 70°C but is almost independent of the dose rate. An interesting discovery is that PTFE, a hydrophobic polymer, forms as a stable latex in the absence of emulsifier. When PTFE latex coagulates during polymerization under certain conditions, the polymerization rate decreases, probably because polymerization proceeds mainly on the polymer particle surface. The observed rate acceleration and successive increase in polymer molecular weight may be due to slow termination of propagating radicals in the rigid PTFE particles.
Photolytic behavior of truxillic and truxinic polyamides
Authors: Caccamese S. , Maravigna P. , Montaudo G. , Recca A. , Scamporrino E.
Published: April 2003

The effect of strong acids on the photolysis of stereoisomeric polyamides containing photoreactive cyclobutane units was studied, and a drastic increase in the photolytic rates was observed. Protonation of amide groups can explain the mechanism of this catalytic effect, being the photolytic rates affected not only by the steric congestion around the cyclobutane ring but also by the basicity of the amide group as a function of the substituent. Molecular weight decrease of the irradiated polymers was monitored by viscosity measurements, and it was found sensibly affected by the presence of small amounts of strong acids.
Diad, triad, and pentad sequence‐distribution analysis of acrylonitrile–vinylidene chloride model copolymers by 13C‐NMR
Authors: Bailey D. B. , Henrichs P. M.
Published: April 2003

The DMSO solution copolymerization of acrylonitrile and vinylidene chloride can be adequately described by the terminal‐unit copolymerization model. The sequence distribution measured by 13C‐NMR is in excellent agreement with the theoretically calculated diad, triad, and pentad distributions. The variation of glass transition temperatures with copolymer composition is explained by sequence distribution.
Storage stability of reactive phenolic dispersions
Authors: Leung M. S. , Wu Y. T. , Jones T. R. , Ancker F. H. , Covitz F. H.
Published: April 2003

Storage stability of an aqueous phenolic dispersion resin has been studied by accelerated methods with chemical kinetics and centrifugation. The activation energy of the resin advancement reaction was 25.6 kcal/g mole. Results indicate that the chemical and physical properties of the dispersion resin do not change significantly in a storage period of 4.5 months under normal conditions (25°C). Under refrigeration (4°C) the product is stable indefinitely for all practical purposes.
Copolymerization of vinyl cyclohexane and α‐methyl vinyl cyclohexane with acrylonitrile
Authors: Kharas G. B. , Kleiner V. I. , Stotskaya L. L. , Krentsel B. A. , Lukina G. G.
Published: April 2003

Copolymerization of vinyl cyclohexane and α‐methyl vinyl cyclohexane with acrylonitrile in the presence of a complexing agent AlEtCl2 results in the formation of alternate copolymers. In the copolymerization of vinyl cyclohexane with acrylonitrile the copolymer composition depends on the ratio of acrylonitrile to AlEtCl2. If this ratio is unity, alternating copolymers of the composition 1:1 are formed; with a ratio greater than unity statistical copolymers that contain more than 50% acrylonitrile units are produced. The 1H‐NMR spectroscopy measurements indicate that the interaction between the comonomers and the complexing agent leads to the formation of ternary donor–acceptor complexes of equimolar composition. The equilibrium constants of these complexes at −60°C have been determined. The effects of temperature, nature of solvent and dilution on the yield, and composition of the copolymers of vinyl cyclohexane with acrylonitrile formed have been studied. By lowering the temperature the yield of copolymers increases but their composition remains equimolar. An increase in the polarity of the medium results in an increase in copolymer yield, whereas the yield decreases if the reaction is conducted in a donor‐solvent medium. Dilution of the reaction mixture disrupts the alternation of units in the macrochain of copolymers. The kinetic pecularities of copolymerization have been investigated. The linear dependence of the copolymerization rate on the product of comonomer concentration is observed. The rate of copolymerization is proportional to the square root of the incident light intensity. Various additions of radical type and irradiation accelerate the process of copolymerization. The mechanism of alternating copolymerization of vinyl cyclohexane monomers with acrylonitrile in the presence of AlEtCl2 is discussed in terms of homopolymerization of the comonomer complex.
The preparation of poly(N‐acetyl‐α‐amino acrylic acid) [poly(N‐acetyl dehydroalanine)] and poly(α‐amino acrylic acid) (polydehydroalanine)
Authors: Asquith R. S. , Gardner K. L. , Yeung K. W.
Published: April 2003

Poly(N‐acetyl‐α‐amino acrylic acid) was prepared by a free radical polymerization reaction. Mild alkaline hydrolysis of the polymer product yielded a second polymer poly(α‐amino acrylic acid) (polydehydroalanine). Both polymers exhibited certain polyelectrolyte behavior, although the latter did not behave as expected for an amphoteric polyelectrolyte.
Polymerization of methyl methacrylate initiated by Mn(III)–glycerol redox system
Authors: Nayak Padma L. , Samal Rajani K. , Nayak Mohan C.
Published: April 2003

The kinetics of thermal polymerization of methyl methacrylate initiated by the redox system Mn(III)–glycerol was studied in aqueous sulfuric acid in the temperature range of 30–40°C, and the rates of polymerization, Rp, and Mn3+ disappearance, etc., were measured. The effect of certain water‐miscible organic solvents and certain cationic and anionic surfactants on the rates of polymerization has been investigated. A mechanism involving the formation of a complex between Mn3+ and glycerol whose decomposition yields the initiating free radical with the polymerization being terminated by the metal ion has been suggested.
Photopolymerization of methyl methacrylate sensitized by aliphatic ketones
Authors: Lissi E. A. , Encina M. V. , Abarca M. T.
Published: April 2003

The polymerization of methyl methacrylate photosensitized by several alkyl ketones has been investigated. It was found that alkyl ketones can induce the free radical polymerization of the monomer with an efficiency that increases when the triplet lifetime decreases. For ketones of similar triplet lifetime those decomposing predominantly by a type I photocleavage show greater initiation efficiencies than those that react by a type II mechanism. The results obtained show that quenching of the excited ketones by the monomer does not induce polymerization. For ketones bearing γ‐hydrogens the initiation is due to the 1,4‐biradical produced by intramolecular hydrogen abstraction.
The chemistry of THPC–urea polymers and relationship to flame retardance on wool and wool‐polyester blends. I. Chemistry of THPC–urea polymers
Authors: Basch Avraham , Zvilichovsky Bina , Hirshmann Bella , Lewin Menachem
Published: April 2003

Polymer formation from THPOH‐urea, THPOH‐dichloropropanol‐urea, and THPC‐urea was studied. Order and rate of urea addition were shown to influence insoluble polymer yields as well as polymer structure. The polymers were characterized by elemental analyses and infrared spectroscopy, and predominant structures proposed. The structures were correlated with thermogravimetric and differential scanning calorimetry data and probable thermal decomposition paths.
Linear dimerization of 1‐phenylbutadiene by acid catalysts
Authors: Higashimura Toshinobu , Hasegawa Hiroshi
Published: April 2003

This article describes the linear dimerization of 1‐phenylbutadiene by three catalysts (CF3SO3H, CH3COCIO4, and BF3OEt2) under a variety of conditions. With CF3SO3H catalyst the unsaturated linear dimer was formed selectively (75–85%) in a high yield by the proper choice of conditions; for example, at 70°C in benzene at low monomer concentrations (0.05–0.10 mole/liter). The dimerization was promoted in less polar solvents, at lower monomer concentrations, and at higher temperatures. In contrast, BF3OET2 gave only high‐molecular‐weight oligomers at 50°C in benzene. The structure of the dimer obtained with CF3SO3H was analyzed by infrared (IR) and 1H‐NMR spectroscopy and was concluded to be
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which may be formed via 3,4‐and 1,4‐addition, respectively. Nuclear magnetic resonance (NMR) spectra also showed that the oligomers produced by BF3OEt2 carry cyclic groups—one at the chain end and the other(s) attached to the main chain. Thus it was revealed that the nature of catalysts could control not only the molecular weight but the structure of oligomerization products.
Mechanism of the NCA polymerization. VI. Investigations on cocatalysts of the base‐initiated NCA polymerization
Authors: Kricheldorf Hans R.
Published: April 2003

The triethylamine‐initiated polymerization of glycine‐NCA [N‐carboxylic acid anhydrides (oxazolidine‐2,5‐diones)], L‐alanine‐NCA, and sarcosine‐NCA, as well as the pyridine‐initiated polymerization of sarcosine‐NCA, were carried out in the presence of potential cocatalysts. The 11 electrophilic reagents tested in this work can be divided into two classes: N‐acyllactams and similar compounds, which are less reactive than the monomers and have no influence on the polymerization; and isocyanates and N‐acyl‐NCAs or ‐NTAs [N‐thiocarboxylic acid anhydrides (thiazolldine‐2,5‐diones)], which are more electrophilic than the monomers and behave as cocatalysts in the case of glycine‐NCA and alanine‐NCA, since their base‐initiated polymerization proceeds via the attack of NCA anions on the electrophilic N‐acyl NCA chain and (“activated monomer mechanism”). In the case of sarcosine‐NCA, however, the propagation involves a nucleophilic chain end (“carbamate mechanism”) and the strong electrophilic reagents behave as inhibitors.
Cyclic acetal‐photosensitized polymerization. VII. Photopolymerization of 2‐vinyl‐4‐hydroxymethyl‐1,3‐dioxolane
Authors: Ouchi Tatsuro , Nakamura Takaki , Yonekura Kuniharu
Published: April 2003

In order to assess the effect of the methylol group at the 4‐position of 1,3‐dioxolane on polymerization, the photopolymerization of 2‐vinyl‐4‐hydroxymethyl‐1,3‐dioxolane (VHDO) was carried out in benzene at 40°C. The reaction scheme of VHDO was considered to be the same as that of 2‐vinyl‐1,3‐dioxolane (VDO). The rate of polymerization and the molecular weight of polymer were small because of the degradative chain transfer by allylidene group. Moreover, the rate of polymerization of VHDO was greater than that of VDO, whereas the molecular weight of polymer of VHDO was less than that of VDO.
Dilute solution properties of methyl methacrylate—acrylonitrile copolymer (MA2)
Authors: Kashyap A. K. , Kalpagam V.
Published: April 2003

This article deals with studies of the dilute solution properties of methyl methacrylate‐acrylonitrile (MMA‐AN) copolymer of 0.415 mole fraction (mf) of acrylonitrile composition. Mark—Houwink parameters for this copolymer have been evaluated in acetonitrile (MeCN), 2‐butanone (MEK), dimethyl formamide (DMF), and γ‐butyrolactone (γ‐BL). The Mark‐Houwink exponent a in all four solvents at all temperatures is larger than the corresponding values of the parent homopolymers. The solvent power is in the order of DMF < γ–BL < MEK < MeCN; [η] decreases with an increase in temperature, which is behavior characteristic of polymers in good solvent. The unperturbed dimensions (K0) values, obtained by the Stockmayer–Fixman method, are lower than those for the parent homopolymers and depend on solvent as well as temperature. The solute—solvent interaction parameter X1 values are close to 0.5; X1 is independent of temperature. The excess interaction parameter XABvalues are negative. The results for this copolymer system in regard to low second virial coefficient A2, large X1, and high a values suggest that the large extension of these copolymer chains is due to the unusual short‐range interactions.
Alternating polyampholytes prepared by hydrolysis of copolymer of maleic anhydride and N‐vinylsuccinimide
Authors: Furukawa Junji , Kobayashi Eiichi , Doi Toshiki
Published: April 2003

Alternating polyampholytes (MA‐VA) containing two acidic groups and one basic group were prepared by the copolymerization of maleic anhydride (M1) and N‐vinylsuccinimide (M2) at 60°C with AIBN as the initiator, followed by acid hydrolysis with 1N hydrochloric acid at 140°C for 24 hr. The monomer reactivity ratios r1 and r2 are 0.025 and 0.06, respectively. The structure of polymers was discussed on the basis of the data of their elementary, infrared (IR), and thermal analyses and the binding ability of heavy metal ion. Polyampholytes were soluble in strong acidic and basic media but were precipitated in the pH range 3–4. An isoelectric point at pH 3 was determined by potentiometric titration and the turbidimetric method. By thermal treatment above 205°C the polyampholyte turned quantitatively into a cyclized lactam. This suggests that the polyampholyte MA–VA has an intramolecular hydrogen bond between the amino and γ‐carboxyl groups. The binding of Cu2+ and Hg2+ by the polyelectrolyte was evaluated by equilibrium dialysis.
Synthesis and properties of alternating copolymers of potential antitumor activity containing 5‐fluorouracil
Authors: Umrigar Pesi P. , Ohashi Shinichi , Butler George B.
Published: April 2003

“Pyran” copolymer, the 2:1 regularly alternating cyclocopolymer (DVE—MA) of maleic anhydride (MA) and divinyl ether (DVE), first discovered in 1951, has been investigated extensively, both from the standpoint of its chemical structure and its biological activity. Although certain aspects of its structure remain to be determined, it has been shown to possess a wide spectrum of biological activity. It possesses antitumor activity and has been investigated clinically. During the clinical investigation, it was found to be an interferon inducer. Interferon is a protein which appears to be the body's first line of defense against viral infection. DVE—MA also possesses antiviral, antibacterial, antifungal, antiarthritic, and anticoagulant properties, activates macrophages, inhibits reverse transcriptase, and is capable of elimination of Pu. During the course of investigations in these laboratories, many structural modifications of DVE—MA have been made. Many of these modifications also possess considerable antitumor activity and interferon‐induction capability. Perhaps the most interesting structural modification has been the incorporation of 5‐fluorouracil (5‐FU) into the polymer (NSC 255083). This polymer has shown (T/C)% [= ratio of test (T) to control (C) survival times] = 189 for dose by intraperitoneal injection of 200 mg/kg animal weight in CD2F1 mice (6/6 survivors after fifth day) against P388 lymphocytic leukemia. This article describes the synthesis of both the monomer and copolymer, and a study of the hydrolytic rate of release of 5‐FU from the polymer.
Effect of ferric chloride on acid hydrolysis of viscose rayon
Authors: Shinouda H. G. , Moteleb M. M. Abdel , Kinawi A.
Published: April 2003

A comparison between the fine structure of viscose hydrocelluloses prepared by acid hydrolysis of viscose fibers in the absence and presence of ferric chloride is given. The results indicate that ferric chloride has little effect on the change in x‐ray crystallinity indices accompanying acid‐hydrolysis of the fibers. On the other hand, specific volume results show that the inner fine structure of hydrocelluloses prepared by hydrolyzing the fibers with free acid differs from that for hydrocelluloses prepared with an HCl‐FeCl3 reagent.
Vinyl polymerization. 364. Polymerization of methyl methacrylate initiated with benzaldehyde
Authors: Imoto Minoru , Maeda Takamasa , Ouchi Tatsuro
Published: April 2003

Benzaldehyde (PhCHO) is found to be able to initiate the radical polymerization of methyl methacrylate (MMA). The rate of polymerization is expressed by the following equation: Rp = const[PhCHO]0.5[MMA]1.5. The overall activation energy is estimated to be 56.3 kJ mole−1. The mechanism of polymerization is discussed.
Homopolymerization of propylene oxide and copolymerization of propylene oxide and carbon dioxide with metal salts of acetic acid
Authors: Soga Kazuo , Uenishi Kazuya , Ikeda Sakuji
Published: April 2003

The homopolymerization of propylene oxide was first conducted at 80°C in the absence of any solvent by using various metal salts of acetic acid and it was found that Mg(OAc)2, Cr(OAc)3, Mn(OAc)2, Co(OAc)2, Ni(OAc)2, Zn(OAc)2, and Sn(OAc)2 were effective for the polymerization. The copolymerization of propylene oxide and carbon dioxide was next examined by using these effective metal salts of acetic acid as catalysts. Most of these were effective also for the copolymerization. The nature of the polymer obtained was strongly dependent on the catalyst used. Co(OAc)2 and Zn(OAc)2 gave an alternate copolymer of propylene oxide and carbon dioxide, Mg(OAc)2, Cr(OAc)3, and Ni(OAc)2 gave a random copolymer, while Sn(OAc)2 gave a homopolymer of propylene oxide. Then the copolymerization of propylene oxide and carbon dioxide was kinetically investigated in some detail by using Co(OAc)2 as a catalyst. On the basis of the results obtained, a plausible mechanism was proposed for both the homopolymerization of propylene oxide and copolymerization of propylene oxide and carbon dioxide.
Isolation of the complex between acrylonitrile and trimethylaluminum
Authors: Koma Yasuo , Koide Naoyuki , Tanaka Akira , Iimura Kazuyoshi , Takeda Masatami
Published: April 2003

The complex of acrylonitrile (AN) with trimethylaluminum (AlMe3) was successfully isolated as a white needlelike crystal with a melting point of 42.5°C. In this article the preparation of the complex is described in detail. Cryoscopic and spectral investigations indicated that the complex is formed by an equimolar ratio of AN and AlMe3. From the measurement of the x‐ray diffraction photograph of the crystal the repeat period was determined to be 9.47 ± 0.05 Å.
Asymmetric induction copolymerization. Cationic copolymerization of l‐menthyl vinyl ether with indene and acenaphthylene
Authors: Kurokawa Masahiro , Yamaguchi Hidemasa , Minoura Yuji
Published: April 2003

l‐Menthyl vinyl ether (l‐MVE) was homopolymerized and copolymerized with the monomers indene (IN) and acenaphthylene (ANp) by BF3OEt2 as a catalyst. The chiral menthyl substituent was cloven from the homopolymers and copolymers using dry‐hydrogen bromide gas. After the removal of optically active menthyl group, poly(vinyl alcohol) (PVA) from l‐MVE homopolymer was optically inactive, and copolymers (VA‐IN, VA‐ANp) from l‐MVE‐IN and l‐MVE‐ANp copolymers were still optically active. Hence, in the case of l‐MVE homopolymer, it was concluded that asymmetric induction in the polymer main chain can only produce pseudoasymmetry. In the case of l‐MVE‐IN and l‐MVE‐ANp copolymers, it was found that asymmetric induction proceeded in the copolymer main chain and was caused by the influence of chiral menthyl group.
Electric conductivity of TCNQ salts of ionene polymers containing triethylenediammonium or 4,4′‐bipyridilium ring
Authors: Kamiya Tamotsu , Goto Kuniyuki , Shinohara Isao
Published: April 2003

The ionene polymers were prepared by the Menshutkin reaction of α,ω‐dibromoalkane (n) with triethylenediamine (TDA) or 4,4′‐bipyridil (BP). Resistivities (p) and activation energies of conduction (Ea) were measured for the polymeric 7,7,8,8‐tetracyanoquinodimethan (TCNQ) salts with these ionenes. The correlation between the chemical structure of the ionenes and the conductivity was discussed. In the TDA,n‐TCNQ complex salts and the BP,n‐TCNQ simple salts the salts of the ionenes containing even numbers of CH2 groups showed higher conductivities than those of the ionenes containing odd numbers of CH2 groups. The conductivities determined by the narrower interval between the N+ cations of the main chains were measured in the simple salts. In the complex salts the conductivities determined by the larger interval were measured. The conformational change of the matrix ionenes affected the arrangement of the TCNQ molecules. The values of p were 79.7 and 12.5 Ω cm, and the values of Ea were 0.122 and 0.063 eV for TDA,4‐TCNQ complex salt and BP,5‐TCNQ complex salt, respectively.
Electric conductivity of polymer composites with 7,7,8,8‐tetracyanoquinodimethan salts
Authors: Mizoguchi Katsuhiro , Kamiya Tamotsu , Tsuchida Eishun , Shinohara Isao
Published: April 2003

The electric properties of polymer composites with highly conductive 7,7,8,8‐tetracyanoquinodimethan (TCNQ) salts such as quinolinium–TCNQ complex salt (), acridinium–TCNQ complex salt (), and N‐methylacridinium–TCNQ complex salt () were studied. Polyacrylonitrile (PAN), poly(N‐vinylcarbazole) (PVK), and poly(4‐vinylpyridine), (P4VP), etc., were chosen as matrix polymers. The resistivity (ρ) of the was 0.37 Ω cm at the content of 20 wt % in the film. When the content of was increased up to 40 wt%, a phase separation of the needle crystals was observed and the ρ value increased. When was dispersed into PAN or PVK, the separation was also observed and the samples showed low conductivity. The uniform films were obtained in the and systems, but the values of ρ were high because of the degradation of the TCNQ salts. Uniform films with the naked eye were obtained in the and systems, and the values of Ω were 0.37, 1.05, and 3.40 Ω cm, respectively. was stable even when dispersed into P4VP. The properties of the composites were influenced by the combination of the TCNQ salts and the polymers. The uniformity and the stability of the composites were necessary to obtain the high conductive composites.
Some aspects of the polymerization of n‐butyl vinyl ether by chromyl chloride
Authors: Biswas Mukul , Kabir G. M. Ahsanul
Published: April 2003

The rate of n‐butyl vinyl ether polymerization by chromyl chloride is first order in [catalyst] and second order in [monomer]. Added H2O (after a certain concentration) and HCl increase the rate, thiophene retards the rate, while pyridine inhibits the rate. DP is independent of [chromyl chloride] and increases with increasing [monomer] up to 1M, thereafter becoming independent of it. Both rate and DP increase over the range 10−32°C and decrease at higher temperatures.
Nonclassical urea oligomers. IV. Polymerization of (S)‐1‐(N‐phenyl‐carbamoyl)‐2‐methylaziridine. A synthesis of optically active crystalline oligomer with narrow molecular weight distribution
Authors: Araki Takeo , Nagata Koichi , Tsukube Hiroshi
Published: April 2003

In the presence of Et2SO4, (S)‐1‐(N‐phenyl‐carbamoyl)‐2‐methylaziridine gave an oligomer with a structure of [CH2CHCH3N(CONHPh)]n. The oligomer has optically active isotactic configuration and narrow molecular weight distribution (DP ca. 8). The net polymerization behavior of the monomer and chemical property, such as absorptivity of Et2SO4, of the oligomer are analogous to the case of 1‐(N‐phenyl‐carbamoyl)‐aziridine. The ring opening occurs with retention of the configuration at the asymmetric carbon atom and the oligomer can be crystallized at around 90°C.
Thermal degradation of poly(vinyl chloride): effect of oxygen on the thermal degradation of poly(vinyl chloride)
Authors: Gupta V. P. , St. Pierre L. E.
Published: April 2003

On the basis of the simultaneously measured free radical generation and HCl evolution a mechanism accounting for the effect of the oxygen on the degradation of poly(vinyl chloride) (PVC) is proposed. The mechanism is based on the reaction of oxygen with radicals generated in PVC to form unstable peroxy radicals. In addition, it is proposed that oxygen reacts directly with conjugated polyenes to form peroxy linkage.
Photoinduced ionic polymerization. VII. Cationic polymerization of cyclohexene oxide in solid state
Authors: Irie Masahiro , Sasaoka Senzo , Yamamoto Yukio , Hayashi Koichiro
Published: April 2003

Photopolymerization of cyclohexene oxide in the presence of electron acceptors was studied in a bulk system (in liquid as well as in solid states). The polymerization was proved to proceed by a cationic mechanism in both states by the effect of inhibitors. In a liquid phase the light intensity dependence of the rate of polymerization and the molecular weight distribution showed a contribution of a free ionic polymerization. Any discontinuous phenomenon in the rate as well as in the molecular weight was not discerned between liquid(above −36°C) and plastic crystal (between −36 and −81°C) phases. A quantum yield of monomer consumption as high as 8 × 103 was observed in the plastic crystal phase. Below −81°C in the normal crystal phase the rate as well as the molecular weight was remarkably suppressed.
Neighboring effect of the sodium carboxylate group on the saponification of diallyl phthalate prepolymer
Authors: Imai Itsuro , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

The neighboring effect of sodium carboxylate groups on the saponification of diallyl phthalate prepolymer was investigated in detail in dioxane solutions that contained various amounts of water at 50°C by using different types of model compound; this procedure is also compared with the neighboring effect of hydroxyl groups.
The reaction of diphenyl carbonate with amines and its application to polymer synthesis
Authors: Yamazaki Noboru , Iguchi Tadao , Higashi Fukuji
Published: April 2003

Selective formation of biscarbamates from diphenyl carbonate (DPC) and diamines and the preparation of polyurethanes from the carbamates and diols under mild conditions were studied. The reaction of DPC and diamines was significantly affected by catalysts, biscarbamates being exclusively prepared in high yields in the presence of 2‐hydroxypyridine. The polycondensation reaction of the biscarbamates with diols was facilitated by catalysts such as metal salts; among the catalysts examined magnesium chloride in pyridine gave the best results. Metal chlorides in pyridine also promoted the reaction of DPC with aromatic amines to give the corresponding ureas, and the direct synthesis of polyureas was achieved by the polycondensation of DPC with diamines in the presence of the chloride.
The chain configurational properties of novolak p‐cresol–formaldehyde resins
Authors: Tobiason Fred L.
Published: April 2003

Rotational isomeric state chain configurational analysis has been applied to the p‐cresol–form‐aldehyde chain structure. Steric interference allows the chain to be considered by using a twofold potential energy barrier. The bond rotational angles and conformational energies were set empirically to fit existing experimental dipole moment data, and the conformational angles were ±45° with a 132 cal/mole energy barrrier separating the g±g± from the g±g± rotational states. The data predict the existence of a cyclic tetramer in support of other researchers' experimental work. The limiting dipole moment ratio and characteristic ratio were computed to be 5.87 and 21.23, respectively. Support for this structure will have to wait for experimental data from higher‐molecular‐weight materials.
Esca applied to polymers. XXIII. RF glow discharge modification of polymers in pure oxygen and helium–oxygen mixtures
Authors: Clark D. T. , Dilks A.
Published: April 2003

The oxidation of polyethylene, polypropylene, and polystyrene by exposure to plasmas excited in pure oxygen and helium–oxygen mixtures at low power levels has been studied. A detailed curve resolution procedure is outlined, and the rate of oxidation is shown to be a strong function of the polymer structure for pure oxygen plasmas, as is the composition of the oxidized layer; this is not the case, however, for oxidation effected by helium–oxygen mixtures. It seems likely, from a consideration of the available data, that the oxidation is confined to the outermost monolayer and is initiated by a crosslinking mechanism that involves oxygen‐containing functionalities.
Electrochemical bulk polymerization of methyl methacrylate in the presence of nitric acid
Authors: Pistoia Gianfranco , Bagnarelli Ovidio
Published: April 2003

The electroinitiated polymerization of methyl methacrylate in the presence of nitric acid has been investigated on platinum and graphite anodes. The dependence of yields and molecular weights on parameters such as current density, temperature, speed of stirring, and HNO3 concentration was determined. Under continuous electrolysis conditions a stationary state takes place and the rate of polymerization exhibits zero order with respect to monomer and a 1.5 order with respect to current. On the other hand, under postpolymerization conditions a kinetic gel effect occurs, which limits the termination rate and leads to the typical acceleration in the conversion–time curves. The effect of postpolymerization is so marked, even after supplying small amounts of charge, that the formation of long‐lived radical chains is believed to be possible. In this respect HNO3 would play a fundamental role by stabilizing the growing radicals.