bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between dyes and polyelectrolytes. VI. Metachromatic behavior of methylene blue induced by potassium poly(vinyl sulfate) and its homologs
Authors: Shirai Masamitsu , Nagatsuka Tatsuki , Tanaka Makoto
Published: April 2003

Effect of structure of potassium poly(vinyl sulfate) and its homologs on the metachromatic behavior of methylene blue was investigated spectrophotometrically. The metachromatic behavior with addition of polyanions was followed by the changes in the molar extinction coefficient of the 664 nm band of methylene blue and in the wavelength of metachromatic band. Important factors for metachromasy were the number of anionic sites per polymer molecule, the degree of polymerization, and the flexibility of polymer chain. It was found that the amount of KCl or urea required to destroy the metachromasy was a useful measure for estimating the binding strength of methylene blue to polyanions.
Synthesis and properties of new potentially nonthrombogenic polymeric materials
Authors: Ferruti Paolo , Arnoldi Daniela , Marchisio Maria Antonietta , Martuscelli Ezio , Palma Mario , Riva Fernando , Provenzale Luciano
Published: April 2003

A new family of block copolymers have been synthesized and characterized. These copolymers have a central block deriving from the polyaddition of N,N′‐dimethylethylenediamine to 1,4‐bis‐acryloylpiperazine, and lateral blocks of polystyrene. Preliminary biocompatibility tests have demonstrated that these new products show promise as long‐acting nonthrombogenic materials.
Nouvelle méthode de détermination des taux de réativité des copolymères par résonance magnétique nucléaire: Application aux poly(méthacrylate de méthyle–chlorure de vinylidène)
Authors: Chiang Ta Chi , Pham Quang‐Tho , Guyot Alain
Published: April 2003

Constant‐composition copolymers of methyl methacrylate and vinylidene chloride produced by radical copolymerization are studied by 1H‐NMR at 60 and 250 MHz. The different methods of the literature for the derivation of reactivity ratios from either the copolymer composition or the sequence average lengths, or even the diad distribution, are applied but lead to rather dispersed results. A new graphical method is proposed, based on the use of peculiar values of the triad distribution functions. It allows us to detect a penultimate effect for the vinylidene chloride‐rich region. In the same range, a change in tacticity of the diads and triads on the methylmethacrylate sequences, as compared with homopolymers, is observed; it suggests that the anomaly is caused by the competition of the depropagation reaction.
Mechanism of emulsion polymerization of styrene in soap‐free systems
Authors: Goodall A. R. , Wilkinson M. C. , Hearn J.
Published: April 2003

The formation and growth of monodisperse polystyrene latex particles in the absence of added surfactant has been studied by sampling polymerization reactions at different times and determining the surface and bulk properties of the latex. A large number of nuclei in excess of 5 × 1012/ml were generated during the first minute of reaction, but this fell due to coagulation until a constant number (1011−1012/ml) was reached. The rate of polymerization per particle was then found to be proportional to the particle radius. Gel‐permeation chromatography has shown that the initial particles consist mainly of material of MW 1000 with a small amount of polymer up to MW 106, and the presence of this low molecular weight polymer, which in many cases can still be detected after 100% conversion, is taken as being indicative of particle formation via a micellization‐type mechanism involving short‐chain (MW 500) free‐radical oligomers. M̄n values determined for the latex particles throughout the course of reactions show that the molecular weight increases to a maximum of about 105 as the particles grow. The presence of anomalous regions within the particles has been confirmed by transmission electron microscopy, scanning electron microscopy, and gas adsorption studies. It has also been found possible to re‐expose these regions within apparently homogeneous particles by stirring with styrene monomer; this is indicative of a molecular weight heterogeneity within the latex particles. The presence of sulfate, carboxyl, and hydroxyl groups upon the latex particle surfaces has been determined by conductometric titration.
Cationic graft copolymerization of styrene onto poly(vinyl chloride) initiated by phosphorus trichloride
Authors: Taninaka Takumi , Iwamoto Kohji , Minoura Yuji
Published: April 2003

The effect of some organic halides on the cationic polymerization of styrene (St) initiated by phosphorus trichloride (PCl3) was studied to clarify the initiation mechanism on the cationic polymerization. Addition of organic halides caused an acceleration to some extent. Further, cationic graft copolymerization of St onto poly(vinyl chloride) and polychloroprene was carried out. In each case, grafting efficiency was lower than 10%. These results in the cationic polymerization of St by PCl3 in nitrobenzene support the assumption that the initiation step is caused by the dissociation of two molecules of PCl3 to ion pairs.
Studies of vulcanization with tetramethylthiuram disulfide and sulfur vulcanization accelerated by tetramethylthiuram disulfide of styrene–butadiene rubber in presence and absence of dicumyl peroxide
Authors: Das C. K. , Ghosh A. K. , Banerjee S.
Published: April 2003

The salient features of nonelemental sulfur vulcanization by tetramethylthiuram disulfide (TMTD) and elemental sulfur vulcanization promoted by TMTD both in presence and absence of ZnO and stearic acid have been studied. In stock containing TMTD, a higher rate constant value for dicumyl peroxide (DCP) decomposition was observed. TMTD decreases the crosslinking density due to DCP depending on its concentration. An entirely radical mechanism has been advanced in the absence of ZnO. ZnO or ZnO–stearic acid seems to alter the entire course of reaction. The rate of crosslinking increases in the presence of ZnO or ZnO–stearic acid. Moreover, crosslinks are formed additively (further supported from the activation energy data), and mixed crosslink formation has been confirmed by the methyl iodide test of the vulcanizates. Stearic acid has no effect on crosslink formation. An ionic chain mechanism has been postulated in the presence of ZnO, as suggested by British authors.
Binding of Cu(II) to poly(methacrylic acid)
Authors: Kolawole E. G. , Mathieson S. M.
Published: April 2003

The binding of Cu(II) ions to partly neutralized poly(methacrylic acid) (PMA) has been investigated by potentiometric titration and dialysis to determine the stoichiometry the Cu–PMA complexes formed. Partly ionized PMA was titrated with solutions of the metal ion to enable a large range of metal ion/polymer ratios to be studied. Combination of the results from these two techniques at ionic strength 0.1 indicates that at very low Cu(II)/polymer ratios, a 4:1 complex exists, but at higher ratios the complex breaks down to give a mainly 2:1 coordination with some 1:1 binding. Conductance titrations support these results. Viscometric titrations show strong interactions between the metal and polymer, preventing the full extension of the polyion at high degrees of ionization, and spectrophotometric titrations support the existence of at least two types of complexes in the solution.
Study of the anomalous particles formed during the surfactant‐free emulsion polymerization of styrene
Authors: Cox R. A. , Wilkinson M. C. , Creasey J. M. , Goodall A. R. , Hearn J.
Published: April 2003

The presence of anomalous regions within polystyrene latex particles prepared in the absence of added emulsifier has been investigated. It appears that they arise through loss of monomer from particles consisting of a discrete monomer‐rich region surrounded by a polymer shell. It is likely that in most cases, monomer is lost from the region on evacuation prior to electron microscope examination, although there is some evidence from γ‐irradiated samples (prior to electron microscopy) that loss of monomer can also occur during storage and/or dilution of the sample. Scanning electron microscopy and carbon replication techniques have been used to determine the shapes of the voids. Gas adsorption studies and carbon replication have also served to illustrate that the presence of the regions was not due to electron‐beam damage. The presence of extrusions on some samples has been attributed to incomplete loss of monomer on evacuation due to the thickness of the surrounding polymer shell.
ESCA applied to polymers. XV. RF Glow‐discharge modification of polymers, studied by means of ESCA in terms of a direct and radiative energy‐transfer model
Authors: Clark D. T. , Dilks A.
Published: April 2003

The crosslinking of an ethylene–;tetrafluoroethylene copolymer by exposure to an argon plasma, excited by an inductively coupled RF field, is studied over a wide range of pressures and power loadings. The results are interpreted in terms of a two‐component, direct and radiative energy‐transfer model showing that the outermost monolayer crosslinks rapidly via direct energy transfer from argon ions and metastables.
Copolymerization reactivities and conductivities of some living polymers of p‐substituted styrenes
Authors: Favier J. C. , Sigwalt P. , Fontanille M.
Published: April 2003

A kinetic study in tetrahydrofuran of the addition of 1,1‐diphenylethylene on para‐substituted styrylcarbanions (with Cs+ as counterion) has given the reactivities of free ions and ion‐pairs. For both species, the addition rate constant increased in the following sequence for the substituent of the phenyl ring: pH < p‐CH3 <p‐CH3O. It was also shown that in the same solvent, the dissociation constants of the polystyryl ion‐pairs decreased with the electron‐donating power of the substituent.
Analysis of degradation products by thermal volatilization analysis at subambient temperatures
Authors: McNeill I. C. , Ackerman L. , Gupta S. N. , Zulfiqar M. , Zulfiqar S.
Published: April 2003

In the subambient thermal volatilization analysis (TVA) technique, degradation products initially at −196°C are allowed to warm up to ambient temperature in a controlled manner under vacuum conditions, and volatilization from the sample tube to a trap at −196°C is monitored by means of a Pirani gauge. The technique is discussed in relation to earlier TVA work in which volatilization from a heated polymer sample was followed. Design and operation of a subambient TVA system are described, and examples of the application of the technique to the study of the degradation products of seven polymers are considered.
Some aspects of plasma polymerization of fluorine‐containing organic compounds
Authors: Yasuda H. , Hsu T. S.
Published: April 2003

The polymerization of perfluorocarbons and fluorohydrocarbons was investigated by using both continuous and pulsed rf discharge (100 μsec on and 900 μsec off). Plasma polymerization of perfluorocarbons is generally slower than that of hydrocarbons, which seems to be due to the absence of contribution of fluorine detachment to the plasma polymerization. Presence of multiple bond(s) or cyclic structure in a monomer is necessary to obtain high enough polymerization; however, the plasma polymerization mechanism postulated to plasma polymerization of hydrocarbons is still valid to these monomers. Cyclic structure is very effective to enhance the plasma polymerization capability of perfluorocarbons. Saturated straight‐chain perfluorocarbons do not polymerize well in plasma, but the grafting of fluorine‐containing functions on the surface of polymeric substrate can be achieved by the plasma of these compounds. The effect of pulse on the plasma polymerization was found to be similar to that found for hydrocarbons.
Investigations on poly(vinyl chloride). IV. Effects of metal chlorides on the thermal decomposition of poly(vinyl chloride)
Authors: Iida Takeo , Gotō Kunio
Published: April 2003

The effects of various metal oxides upon the thermal decomposition of poly(vinyl chloride) (PVC) were previously reported. In this work, 23 metal chlorides were investigated to determine their effects on the thermal decomposition of PVC by pyrolysis–gas chromatography at 500°C. Each metal chloride exhibits influences on the course of thermal decomposition of PVC almost similar to the corresponding metal oxide except for a few elements; the metal chlorides from acidic metal oxides accelerate the thermal decomposition of PVC, but the metal chlorides from basic metal oxides do not. On comparing the effects of metal oxides and metal chlorides on the thermal decomposition of PVC, most metal chlorides were found to accelerate the thermal decomposition of PVC more than the corresponding metal oxides, owing to ease of addition of the chlorine atoms released from metal chloride to the dehydrochlorinated chains. It is concluded from these results that the thermal decomposition of PVC containing metal salts is markedly influenced by the ease with which chlorine atoms are released from the corresponding metal chloride.
Reactivity and flammability of conjugated acetylenes
Authors: White D. M. , Quinn C. B.
Published: April 2003

The thermal reactivities of model phenyleneacetylenes and diacetylenes and of poly(butadiynylene‐1,3‐phenylene) have been examined by differential scanning calorimetry and compared with the oxygen indices of the materials. No direct relationship was found between the heat of reaction and the oxygen index in these compounds. However, the heat of reaction, in general, does decrease with increasing molecular weight and is lower for rigid linear molecules than for related angular structures. These observations appear to be due to a lack of solid‐state reactivity in the crystalline phase and retardation in the melt due to viscosity effects related to molecular size and rigidity. The synthesis of model compounds is described.
Aromatic polyether, ‐ketone, ‐sulfones as laminating resins. XI. Polymers derived from 2,2′‐diiododiphenyl‐4,4′‐dicarboxylic acid
Authors: Banihashemi Ahmad , Marvel C. S.
Published: April 2003

Aromatic polyether‐keto‐sulfone polymers and related model compounds have been synthesized from 2,2′‐diiododiphenyl‐4,4′‐dicarboxylic acid and a variety of intermediates. It was hoped to convert them to 2,2′‐diphenylethynyl derivatives which could be cured by rearrangement to give dibenzanthracene units in the chain. Low solubilities and high melting points of the products prevented their use in the desired manner.
Aromatic polyether, ‐ketone, ‐sulfones as laminating resins. XII. Derivatives of 2,2′‐diphenylethynyldiphenyl which cure by an intramolecular cyclization
Authors: Banihashemi Ahmad , Marvel C. S.
Published: April 2003

Polymers made from 2,2′‐diiododiphenyl‐4,4′‐dicarbonyl dichloride, diphenyl ether, and isophthaloyl chloride have been made and converted to the 2,2′‐diphenylethynyl derivatives. Introduction of units of isophthaloyl chloride reduced the melting point of these polymers to about 200°C, and they could then be cured by heating. A good glass laminate was prepared and cured from one of the polymers.
Polymerization of aromatic nuclei. XVII. Catalytic hydrogenation of poly(p‐phenylene)
Authors: Durham Judith E. , Kovacic Peter
Published: April 2003

Hydrogenation of poly(p‐phenylene) (I) in cyclohexane at high temperature and pressure with rhodium catalyst gave, in low yield, oligomers of 1,4‐cyclohexylene(II) in the range of 2–16 cyclohexyl units per chain. Apparently only the low molecular weight fraction in I is reduced because of extreme insolubility. II, which appears to be a novel class, was characterized by molecular weight, 1H‐NMR, 13C‐NMR, and infrared spectra, gas chromatography, and microanalyses. Dicyclohexyl and perhydro‐p‐sexiphenyl served as model compounds for comparison in characterization of II.
Some aspects of plasma copolymerization of acetylene with N2 and/or water
Authors: Yasuda H. , Hirotsu Toshihiro
Published: April 2003

Plasma polymerizations of mixture of acetylene‐N2, acetylene‐H2O, were investigated by using an electrodeless glow discharge from a 13.5‐MHz radiofrequency source. Properties of plasma polymers were examined as functions of mole ratios of N2 and/or H2O to acetylene. The concentration of trapped free radicals and the internal stress in a plasma polymer decreased as the mole ratio of N2 or H2O increased. Water showed the most pronounced effects in those properties at the mole ratio of 0.3. Gas permeabilities increased by the copolymerization of N2 and/or H2O. Surface energies were also investigated by analysis of contact angles of liquids. Copolymerization of N2 caused a remarkable increase in polar contribution of surface energy. Some fundamental aspects of flow‐rate pressure relationship of mixed gases are presented.
Studies of accelerated sulfur vulcanization of styrene–butadiene rubber by N‐cyclohexylbenzothiazol‐2‐sulfenamide in the presence and absence of dicumyl peroxide
Authors: Ghosh A. K. , Das C. K. , Banerjee S.
Published: April 2003

This study embodies the results and discussion of a comprehensive and systematic investigation of the mechanism of sulfuration of styrene–butadiene rubber accelerated by N‐cyclohexylbenzothiazole‐2‐sulfenamide (CBS) with and without activators. Dicumyl peroxide (DCP) has been taken as a chemical aid to distinguish between free‐radical and polar mechanisms of sulfuration. The rate constant for DCP decomposition in presence of CBS and the reduction in crosslink density by CBS have also been studied. With a constant amount of DCP and sulfur the crosslink density increases with increasing CBS concentration. In the presence of ZnO and stearic acid, crosslinking proceeds faster than in a similar system without these ingredients, and with DCP the crosslinks are found to be formed nearly additively as confirmed by methyl iodide treatment of the vulcanizates. In the absence of DCP, the crosslinking is characterized by an induction period, even in presence of ZnO and stearic acid. In the presence of sulfur, the 2‐mercaptobenzothiazole (MSH) or amine or amine salt form crosslinkins by ionic reaction.
Cationic polymerization with boron halides. IV. Elucidation and control of initiation and termination by the help of model experiments
Authors: Kennedy J. P. , Huang S. Y. , Feinberg S. C.
Published: April 2003

The proposition that BCl3‐coinitiated olefin (isobutylene, styrene) polymerizations terminate by chlorination has been corroborated by model experiments. Key experiments showed that under simulated polymerization conditions neither tert‐butyl chloride nor 2‐chloro‐2,4,4‐trimethylpentane reacts with BCl3; that H2O/BCl3 + 2,4,4‐trimethyl‐1‐pentene (TMP) produce 2‐chloro‐2,4,4‐trimethylpentane; and that H2O/BCl3 + isobutylene gives rise to tert‐butyl chloride. Extended model studies demonstrated that certain alkyl and benzyl chlorides produce carbenium ions in the presence of BCl3 and that TMP can readily be alkenylated by using 1‐substituted allyl chlorides in conjunction with BCl3. These experiments led to the discovery that olefin polymerizations may be initiated by suitable allyl or benzyl chlorides and BCl3. Accordingly, polymerizations of isobutylene have been carried out with RCl/BCl3, where R is allyl or benzyl. These experiments suggest that both controlled initiation and termination, i.e., initiation by alkenylation and termination by chlorination, can be achieved with the allyl chloride/BCl3 initiator system opening new avenues toward the synthesis of asymmetric telechelic polymers.
Evaluation of crosslinking and scission yields in the degradation of polystyrene by γ‐irradiation in air
Authors: Nichol J. M. , O'Donnell J. H. , Rahman N. P. , Winzor D. J.
Published: April 2003

A sample of polystyrene with narrow molecular weight distribution (M̄w/M̄n = 1.03) has been formed into a 3‐mm sheet and subjected to γ‐irradiation at 25°C in air. Simultaneous crosslinking and scission of polymer chains resulted. Analyses by velocity and equilibrium sedimentation, gelpermeation chromatography, and osmometry of the polystyrene subjected to doses in the range 0‐90 Mrad, all within the pre‐gel region, have yielded average values of G(S) = G(X) = 0.022 ± 0.002 for the complete sample. Combination of these various experimental techniques has been successful in yielding consistent values of G(S) and G(X) and should be applicable with advantage to other polymers, particularly when neither G(S) nor G(X) is zero. The wide variation in literature values of G(S) and G(X) for irradiation of polystyrene under vacuum precludes any unequivocal conclusion on the effect of air on the radiation yields.
Preparation and structure‐property studies on copolypeptides of γ‐methyl glutamate‐glutamic acid and γ‐methyl glutamate–γ‐benzyl glutamate
Authors: Mohadger Y. , Holaday W. , Wilkes G. L.
Published: April 2003

A series of copolypeptides of poly(methyl glutamate‐glutamic acid) (PBC) and poly(methyl benzyl glutamate) (PMB) were prepared from homopolymeric poly(methyl D‐glutamate) (PMDG) via a variety of synthetic routes. Following their characterization, these copolymers were then investigated via dynamic mechanical spectroscopy, stress‐strain analysis (wet and dry), and wide‐angle x‐ray scattering (WAXS). It was found that the copolymers could be prepared from homopolymeric PMDG with minimal chain degradation or side reactions. The mechanical properties of either series did not follow a simple trend, in that specific properties such as Young's modulus went through either a maximum or minimum with composition ratio of the two comonomers. based on the WAXS studies, some rationalization for this behavior was established. Specifically, the nature of the side‐chain interaction, and therefore chain packing, was strongly affected by comonomer ratio.
Photo‐ and radiation‐induced degradation of vinyl polymers in solution. I. Oxidative degradation of poly(α‐methylstyrene) initiated by photodecomposition of AIBN
Authors: Ikeda Tomiki , Okamura Seizo , Yamaoka Hitoshi
Published: April 2003

The oxidative degradation of poly(α‐methylstyrene) initiated by the photodecomposition of azobisisobutyronitrile was studied at 30°C in benzene solution. The progress of the reaction was followed by measuring the rate of chain scission of the polymer. It has been confirmed by GPC measurements that random scission of the polymer chain occurs in the present system. Chain scission did not occur in the absence of AIBN and oxygen. The rate was proportional to the initiation rate and independent of polymer concentration and oxygen pressure under these experimental conditions. Phenol was an effective inhibitor to this reaction. The mechanism of chain scission during oxidation is discussed, and a six‐membered transition is proposed.
Functional monomers and polymers. XXXVIII. Postirradiation polymerization of 2,3‐dimethylbutadiene in deoxycholic acid canal complexes
Authors: Miyata M. , Morioka K. , Takemoto K.
Published: April 2003

Postirradiation polymerization of 2,3‐dimethylbutadiene in deoxycholic acid canal complexes was studied under various reaction conditions. The polymerization was carried out in degassed sealed tubes since the atmosphere had a large effect upon the polymer yield. Addition of 2,3‐dimethylbutane led to a sharp drop in polymer yield, while hydroquinone showed little effect on the polymerization. The rate of postirradiation polymerization was found to increase with increase in reaction temperature and irradiation dose. The apparent activation energy was obtained as 13.7 kcal/mole in a temperature range between −14 and 30°C. Existence of living free radicals having a long lifetime, the gradual change of the monomer into the polymer within the canals, and the effective spatial control in canals are discussed on the basis of the postirradiation polymerization behavior, nature of the adducts, and the structure of the polymers.
Adsorption of metal ions on crosslinked poly(4‐vinylpyridine) resins prepared with a metal ion as template
Authors: Nishide Hiroyuki , Deguchi Jichio , Tsuchida Eishun
Published: April 2003

Poly(4‐vinylpyridine) (PVP) was crosslinked with 1,4‐dibromobutane with a metal ion as template. The adsorption behavior of copper, cobalt, zinc, and cadmium ions on the obtained resin (DBQP) was studied. The DBQP resin prepared with a metal ion as template preferentially adsorbed the metal ion used as template. The stability constant of the copper complex of DBQP was largest for the DBQP resin prepared with a copper ion as template, which was due to its large entropy change for the complexation.
Analysis of the linear methods for determining copolymerization reactivity ratios. IV. A comprehensive and critical reexamination of carbocationic copolymerization data
Authors: Kelen Tibor , Tüdöus Ferenc , Turcsányi Béla , Kennedy Joseph P.
Published: April 2003

Increased insight into the mechanism of carbocationic copolymerization has been achieved by classifying and reviewing in detail 334 monomer pairs in terms of the extended Kelen‐Tüdös method. The reactivity ratios (r values) of essentially all published olefin–olefin, olefin–vinyl ether, vinyl ether‐vinyl ether, and some miscellaneous systems have been reexamined and classified. Of the systems reviewed, only 121 (36.2%) contained sufficiently detailed information for comprehensive reevaluation and classification. Of these, only 49 (14.7%) were found to contain sufficiently accurate and reliable data to satisfy acceptance in class I, i.e., systems which are adequately described by the conventional copolymer composition equation, while 40 (12%) were accepted only in class I(!), i.e., systems for which the available data are somewhat less reliable than for class I and some caution is in order when employing r values for quantitative purposes. Six (1.8%) monomer pairs were judged to belong to class II, i.e., systems for which the approximations implicit in the conventional copolymer composition equation do not hold and published r values are probably erroneous and misleading. Finally, 26 (7.8%) monomer pairs were placed in class III, i.e., systems that exhibit unacceptable data scatter in the η versus ξ plot and published r values are meaningless. In some instances, even the existence of true copolymers is questioned.
Organometallic polymers. IV. Organometallic modifications of halogen‐containing polymers
Authors: Gal Alon , Cais Michael , Kohn David H.
Published: April 2003

The synthesis of ferrocene‐containing polymers by chemical modification of chlorinated polyethylenes, polyvinyl chloride (PVC), and other halogenated polymers, under Friedel‐Crafts conditions, is described. The effect of reaction conditions on the structure and composition of the products obtained with various substrates was investigated. Soluble polymers of up to 62% ferrocene content were obtained. In most cases, substitution was accompanied by dehydrohalogenation. The ferrocene‐to‐vinylene ratio was higher in the reaction products of chlorinated polyethylenes than in those of PVC.
Effect of polyion conformation on dye binding. I. Fluorescence of acridine orange in the presence of synthetic polyacids
Authors: Muller G. , Fenyo J. C.
Published: April 2003

The interaction between polyelectrolytes and Acridine Orange (AO) has been investigated in the case of poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), and a polycondensate between 1,3‐benzene disulfonyl chloride and L‐lysine (PLL) by visible absorption and fluorescence spectroscopy. The influence of both polymer ionization and polymer/dye ratio (P/D) on the spectral behavior of the bound dye has been studied. The stacking tendency of AO is found lower in the presence of PLL under compact conformation (in an ionization range depending on the nature of the counterion) with correlated enhancement of the green fluorescence of the monomeric species of the bound dye. The disappearance of the green fluorescence and the dimerization of bound AO are directly related to the increased flexibility of polyion chains upon ionization. Some analogy is found between the behavior of bound AO in the presence of very compact PLL chains and that reported for AO in the presence of native DNA, which might be due to specific interactions responsible for a kind of “intercalation” of the monomeric bound dye.
Influence of the fire retardant, ammonium polyphosphate, on the thermal degradation of poly(methyl methacrylate)
Authors: Camino G. , Grassie N. , McNeill I. C.
Published: April 2003

The thermal degradation of ammonium polyphosphate (APP), a commercial fire retardant, and its blends with poly(methyl methacrylate) (PMMA) have been studied by thermal volatilization analysis (TVA) and the degradation products identified. APP degrades under vacuum in three stages. Initially it condenses to an ultraphosphate (<260°C) with release of ammonia and water. Fragmentation follows (260–370°C), giving high‐boiling ammonium salts of phosphate fragments and further ammonia and water. The polyphosphoric acid (PPA) which remains then undergoes extensive Fragmentation (>370°C). In the presence of APP, the normal depolymerization of PMMA to monomer competes with degradation reactions which form high‐boiling chain fragments, methanol, carbon monoxide, dimethyl‐ether, carbon dioxide, hydrocarbons, and char. These additional reactions are initiated principally by the PPA. Intramolecular cyclization occurs, resulting in the formation of anhydride, and ester groups are eliminated, methanol and carbon monoxide being evolved. Further degradation of the modified polymer leads to the other volatile products and the char.
Characterization of diallyl phthalate prepolymers by gel‐permeation chromatography
Authors: Błędzki A. , Prusinska M. I. , Berek D.
Published: April 2003

The polydispersity of diallyl phthalate prepolymers was determined by gel‐permeation chromatography (GPC). The measurements were carried out in tetrahydrofuran and chloroform on Mexel 2000, Poragel, and Styragel polystyrene gels. The influence of the polymerization conditions, initiator, and type of transfer agent on the molecular weight distribution of the prepolymers is shown. Other correlations of interest, such as molecular weight distribution of Dapon 35 and Dapon 201, are also presented.
Physicochemical study of crystals of ethylene–butadiene copolymers
Authors: Cernia E. , Conte G. , D'Ilario L. , Pavel N. V. , Giglio E. , Petri S.
Published: April 2003

Ethylene–butadiene (PEBU) copolymer with low percentage of butadiene was previously investigated by van der Waals potential energy calculations. The trans HCCH group (TDB) was found to show fold‐supporting behavior, so that it was supposed that many TDB's were located on the surface of PEBU single crystals under favorable conditions of TDB concentration and of thickness of crystal platelets. In order to verify this hypothesis, three PEBU samples with a butadiene/(ethylene + butadiene) molar ratio of 2.3% (B), 3.6% (C), and 4.6% (D), by assuming that the HCCH groups are all trans, were studied and compared with a polyethylene (PE) sample (A). Samples A, B, C, and D were grown isothermally at temperatures of 50, 55, 60, 61, 70, 71, 75, and 80°C from dilute xylene solutions. Infrared, differential scanning calorimetry (DSC), small‐angle x‐ray scattering (SAXS), bromination kinetics, and density measurements were performed. B, C, and D lamellar crystals show a long spacing L nearly equal to that of A at crystallization temperatures Tc of 50 and 60°C. For Tc ≥ 70°C, the fold period of samples B, C, and D increases more rapidly than that of A in the order D > C > B. The melting temperature Tm and the enthalpy of fusion ΣHf decrease with increasing content of butadiene, except for B and C, which show nearly equal Tm and ΔHf values. Two peaks appear in the fusion curves at temperatures T1 and T2, T1 > T2. The area of the peak at T2 increases with the butadiene content, and, in the same sample, with Tc. Results of bromination in suspension of B, C, and D single crystals, crystallized in the range 50–71°C, indicate that a high percentage of TDB's react on the fold surfaces. The chemical attack is more successful with crystals grown in the range 60–66°C, and, in the case of sample C, as much as 81% of the TDB's are consumed. The density of the samples increases with both Tc and TDB percentage. On the basis of these observed results a simple model for PEBU is proposed. It is supposed that the copolymerization reaction leads to the formation of defects, consisting of one (b), two (bb), three (bbb), or more sequential molecules of butadiene, almost homogeneously distributed along a macromolecular chain. At very small percentage of butadiene, b defects prevail. The addition of further butadiene gives rise mainly to bb defects, and so on. Thus each kind of defect characterizes PEBU copolymers with a certain butadiene/ethylene molar ratio. The experimental data, valid for low butadiene/ethylene molar ratios, agree with this reasonable model and with the potential energy calculations.
Synthesis of N‐substituted bisitaconimide monomers for use as thermosetting polyimide resins
Authors: Hartford S. L. , Subramanian S. , Parker J. A.
Published: April 2003

Two monomeric N‐substituted bisitaconimides, N,N′‐bisitaconimido‐p,p′‐diphenylmethane and N,N′‐bis(itaconimido‐p,p′‐diphenyl ether), were synthesized from the corresponding diamines. The synthesis was accomplished by reaction of the diamine with itaconic anhydride and cyclocondensation of the resultant bisitaconamic acid. Attempts to use p,p′‐diaminodiphenylsulfone as the diamine gave N,N′‐biscitraconimido‐p,p′‐diphenylsulfone and N‐citraconimido‐N′‐itaconimido‐p,p′‐diphenylsulfone instead of the bisitaconimide. The two bisitaconimides polymerize thermally at 180°C and 225°C, respectively, and yield tough polymers with very high thermal stability.
Synthesis of polydihydropyridazinones from bis(3‐benzoylpropionic acids) and aromatic dihydrazines
Authors: Imai Yoshio , Ueda Mitsuru , Aizawa Tatsuo
Published: April 2003

A new class of polydihydropyridazinones has been synthesized by the solution cyclopolycondensation in m‐cresol of 4,4′‐oxy‐ and 4,4′‐ethylenebis(3‐benzoylpropionic acids) with aromatic dihydrazines such as bis(4‐hydrazinophenyl) sulfone and bis(4‐hydrazinophenyl)methane. The polymers having inherent viscosities of 0.2–0.4 were highly soluble in a wide range of solvents including m‐cresol, N,N‐dimethylacetamide, and pyridine. Thermogravimetric analysis of the polydihydropyridazinones showed initial weight losses commencing at 290–350°C in both air and nitrogen.
Effect of polyion conformation on dye binding. II. Fluorescence of 2‐p‐toluidinylnaphthalene‐6‐sulfonic acid (TNS) in the presence of synthetic polyacid and polybase
Authors: Muller G. , Fenyo J. C.
Published: April 2003

The interaction between 2‐p‐toluidinylnaphthalene‐6‐sulfonic acid (TNS), a hydrophobic fluorescent probe, and poly(2‐vinylpyridinium) polyions (PVP) has been investigated by fluorescence spectroscopy. Both the effect of the charge and the concentration of PVP on the fluorescence behavior of TNS indicate that interaction between TNS and hydrophobic sites present in the PVP chain is responsible for the observed phenomena. It is shown that PVP which exists with predominant hydrophobic regions leads to TNS fluorescence, but some residual charge must be present to facilitate the penetration of the dye into the hydrophobic regions. Various situations existing in some polyelectrolyte systems are discussed.
Phase formation and phase inversion during the bulk precopolymerization of solutions of rubber in styrene–methyl methacrylate
Authors: Karaenev S. S. , Chilingirjan M. K.
Published: April 2003

This paper is a report on the investigation of the phase formation and phase inversion during the bulk‐agitated polymerization of styrene and methyl methacrylate containing dissolved SBR. Microphase separation in the rubber solution began at about the 2% conversion level. That process coincided with a constant level of dynamic viscosity and a sharp decrease in the intrinsic viscosity. Before the phase‐inversion point the system became a multiple “oil‐in‐oil” emulsion. The rubber particles began to form before the phase‐inversion point. In the region of phase inversion, the dynamic viscosity decreased and the intrinsic viscosity showed irregularities. After 20% conversion level, the average parameters of the particles did not change.
Structure and properties of poly(2,5‐dimethylterephthalamides)
Authors: Takatsuka Ryozo , Uno Keikichi , Toda Fujio , Iwakura Yoshio
Published: April 2003

Six methyl‐substituted wholly aromatic polyamides were synthesized from the reaction of 2,5‐dimethylterephthaloyl chloride with p‐phenylenediamine, its 2,5‐dimethyl and 2‐methyl derivatives, m‐phenylenediamine, or its 2‐methyl and 4‐methyl derivatives by solution polycondensation at low temperature. The x‐ray diffraction diagrams of the polyamides obtained exhibit crystal patterns. Density values range from 1.26 to 1.37 g/cm3. NMR spectra determined in concentrated H2SO4 solution are reported. Poly(2,5‐dimethylterephthalamides) have lower thermal stability than the corresponding polyterephthalamides. The increase in solubility of polyamide by the introduction of the 2,5‐dimethylterephthaloyl linkage is accompanied by a decrease in thermal stability. The effect of methyl substituents on thermal properties and solubility is discussed in terms of the packing of polymeric molecules and the extent of hydrogen bonding of the amide groups.
Vinyl polymerization: Kinetics of Ce(IV)–acetophenone‐initiated polymerization of acrylonitrile in acetic–sulfuric acid mixtures
Authors: Rout Anuradha , Rout Swoyam P. , Mallick Nigamananda , Singh Baishnab C. , Santappa M.
Published: April 2003

The polymerization of acrylonitrile (M) initiated by the Ce(IV)–acetophenone (AP) redox pair has been studied in acetic–sulfuric acid mixtures in a nitrogen atmosphere. The rate of polymerization is proportional to [M]3/2, [AP]1/2 and [Ce(IV)]1/2. The rate of disappearance of ceric ion,–RCe, is proportional to [AP], [M], and [Ce(IV)]. The effect of certain salts, solvent, acid and temperature on both the rates have been investigated. A suitable kinetic scheme has been proposed, and the composite rate constants kp 2(k/k/t) and k0/ki are reported.
Free‐radical polymerization of phenylacetylene
Authors: Amdur S. , Cheng A. T. Y. , Wong C. J. , Ehrlich P. , Allendoerfer R. D.
Published: April 2003

The free‐radical polymerization of phenylacetylene initiated by azobisisobutyronitrile at 50°C was studied in bulk and in the presence of benzene and toluene. The polymerization rate is approximately first‐order with respect to the initiator concentration. The number‐average molecular weight of the polymer is independent of the initiator concentration in bulk and is approximately proportional to the monomer concentration in the presence of the two diluents, but independent of their nature. The data are consistent with a mechanism based on first‐order decay of active to inactive radicals. This step appears to exert the major control over kinetic and molecular chain lengths. Chain transfer to the monomer is concluded to be absent or to make only a small contribution to molecular termination.
Radical polymerization of methyl methacrylate in the presence of isotactic poly(methyl methacrylate). VIII. Influence of template concentration
Authors: Gons J. , Straatman L. J. P. , Challa G.
Published: April 2003

The influence of template concentration on the radical polymerization of methyl methacrylate along isotactic poly(methyl methacrylate) template was studied. The polymerizations were carried out on three template polymers with different molar masses in dimethylformamide at −5°C. The initial polymerization rate increased linearly with template concentration until the distribution of template chain segments became homogeneous. At that critical concentration a strong increase in the polymerization rate was observed, whereas still higher template concentrations had only a slight effect on the polymerization rate. The polymerizations were stopped when the weight ratio of formed polymer and template was equal to one. The viscometrically determined molar mass of the formed polymers showed a remarkable behavior in the low template concentration region. It was obviously related to the molar mass of the template polymer and was lower than the molar mass found for blank polymerization. This decrease in molar mass was most pronounced in the case of the lowest template molar mass. It is suggested that nondegradative chain transfer occurring near a template chain end is responsible for this decrease. An increase in the molar mass occurred at the critical concentration, similarly to the change of polymerization rate. However, at still higher template concentrations, where template coils started to overlap each other, the molar mass of the formed polymers increased further. The growing chains could leap from one template chain to another and attain a greater chain length than the blank polymerizate.
Equilibrium anionic polymerization of 4,7‐dioxaoctanal and n‐octanal
Authors: Hashimoto Kazuhiko , Sumitomo Hiroshi , Ohsawa Shinji
Published: April 2003

Equilibrium anionic polymerization of 4,7‐dioxaoctanal (DOA) and n‐octanal (OA) was carried out in tetrahydrofuran in the temperature range of −90 to −68°C, and thermodynamic parameters were evaluated as follows: ΔHss = −4.0 ± 0.1 kcal/mole, ΔSss = −18.4 ± 0.5 cal/mole‐deg, and Tc,ss = −56°C for the DOA system; ΔHsc = −3.4 ± 0.1 kcal/mole, ΔSsc = −15.7 ± 0.4 cal/mole‐deg, and Tc,sc = −59°C for the OA system. Comparison of these values with those in the cases of β‐methoxypropionaldehyde and n‐valeraldehyde made it clear that the aliphatic aldehyde having a longer alkyl group polymerizes with smaller changes of enthalpy and entropy and that the polar‐substituted aldehydes have higher polymerizability than the corresponding unsubstituted aliphatic aldehydes in the temperature range studied. These effects of substituents are interpreted from the viewpoint of the intermolecular interactions of polar groups in monomers and their polymers.
Some reaction variables in the solution synthesis of lead (IV) polyesters
Authors: Carraher Jr. Charles E. , Reese Charlene Deremo
Published: April 2003

A number of reaction variables in the solution synthesis of lead (IV) polyesters were examined. Both electronic nature of the diacid and lead‐containing material is important, with an increase in yield resulting as the nucleophilicity of the salt increases. Diffusion is also an important factor. Reaction is favored by an increase in the concentration of reactants.
Studies on propagating species in cationic polymerization of styrene derivatives by acetyl perchlorate or iodine. IV. Common‐ion salt effect on the polymerization rate and the steric structure of the polymer obtained by acetyl perchlorate
Authors: Higashimura Toshinobu , Takeda Takashi , Sawamoto Mitsuo , Matsuzaki Kei , Uryu Toshiyuki
Published: April 2003

Effects of a common‐ion salt, n‐Bu4NClO4, on the cationic polymerization of styrene and p‐chlorostyrene by acetyl perchlorate were studied in a variety of solvents at 0°C. In polymerization (in CH2Cl2) which yielded polymers with a bimodal molecular weight distribution (MWD), addition of the salt suppressed the formation of higher polymers, but affected neither the molecular weight nor the steric structure of the lower polymers. The polymerization rate decreased with increasing salt concentration and became constant at or above a certain concentration. In nitrobenzene, on the other hand, the MWD of the polymers was unimodal and steric structure was unchanged even in the presence of salt at a concentration 50 times that of the catalyst. However, the polymerization rate and the polymer molecular weight decreased monotonically as salt concentration increased. On the basis of these results, it was concluded that the ion pair in methylene chloride differs from that in nitrobenzene, and that the species in the latter solvent is similar in nature to free ions. The fractional contribution of the dissociated and nondissociated propagating species to polymer formation was determined from the rate depression caused by addition of the salt.
Limiting conversions in two‐phase polymer reactions
Authors: Sundberg D. C. , James D. R.
Published: April 2003

The concepts of limiting conversion in one‐phase polymer reactions have been extended to two‐phase reaction systems. The analysis of the two‐phase reaction requires the consideration of the glass transition temperature of each phase and the distribution of the reacting monomer between the phases. Predicted limiting conversions are compared with experimental data for simple polystyrene and polystyrene–polybutadiene reactions in latex form. Strong agreement is found for these comparisons.
Polymerization of alkoxyallenes by transition‐metal catalysts
Authors: Ghalamkar‐Moazzam Mohsen , Jacobs Thomas L.
Published: April 2003

The structure of polymers obtained by polymerization of methoxyallene and ethoxyallene with transition‐metal catalysts depends on the catalyst employed. Rapid polymerization at 0°C through the unsubstituted double bond occurred with π‐allylnickel halides, NiCl2/AlEt3 and CoCl2/AlEt3, yielding polymers with the structure magnified image Typical Ziegler–Natta catalysts (TiCl4, VOCl3 or FeCl3 with AIEt3) gave polymers mainly with the structure magnified image although some of the structural units were probably present as well. Polymers having conjugated double bonds magnified image were prepared with PdCl2, [(π‐allyl)PdCl]2, and PdCl2(C6H5CN)2 as catalysts. Palladium iodide produced polymers with all three of the above structural units present. Polymerization occurred more slowly with these palladium catalysts. A preliminary examination of the effect of variation of solvent, ligand, co‐catalyst, and temperature on the rate and structure of the polymers obtained with the palladium catalysts is reported.
Chain‐configurational properties of novolac phenol–formaldehyde resins
Authors: Tobiason Fred L. , Cain Greg H. , Gregory Steve M.
Published: April 2003

Rotational isomeric‐state chain‐configurational calculations have been applied to the novolac phenol–formaldehyde structure. Steric interference allows the chain to be considered with a twofold potential energy barrier model. Computations that fit the observed dipole‐moment data over a range of molecular weights indicate that the conformational angle is near ±80°, with the g±g= states on the average being 155 cal/mole below the g±g± states. The limiting dipole‐moment ratio is computed to be 1.47, compared to the experimental value of 1.48. A negative temperature coefficient agrees in sign with the experimental value, and the characteristic ratio of the end‐to‐end molecular dimensions is calculated to be 3.27, as compared to the experimental value of 4.76.
Critical evaluation of conditions of plasma polymerization
Authors: Yasuda H. , Hirotsu Toshihiro
Published: April 2003

Under conditions of plasma polymerization, we are dealing with the “reactive” or “self‐exhausting” rather than the “nonreactive” or “non‐self‐exhausting” gas phase (plasma). Therefore, many parameters that define the gas phase, such as system pressure and monomer flow rate, which are measured in the nonplasma state (before glow discharge is initiated), do not apply to a steady state of plasma, the conditions under which most of the studies on plasma polymerization are carried out. Consequently, information based on: (1) the polymer deposition rate measured at a fixed flow rate and discharge power, (2) the dependence of deposition rate on flow rate at fixed discharge power, or (3) the dependence of deposition rate on discharge power at fixed flow rate, does not provide meaningful data that can be used to compare the characteristic nature of various organic compounds in plasma polymerization. The significance and true meaning of experimental parameters applicable to conditions of plasma polymerization are discussed. The most important feature is that plasma polymerizations of various organic compounds should be compared at comparable levels of composite discharge power parameter W/FM, where W is discharge power, F is the monomer flow rate (given in moles), and M is the molecular weight of a monomer.