bluuebunny/crossref_metadata_2025 huggingface dataset:
Fragmentation in cationic olefin oligomerization
Authors: Larchance Pierre , Eastham Arthur M.
Published: April 2003

The dominant products from the polymerization of butene‐2 in CH2Cl2 at −25°C with BF3CH3OH as catalyst are C10, C12, and C14 olefins. Formed in lesser amounts are C9 and C13 olefins but C5–7 and C11 olefins have not been detected. The few products so far identified retain the basic butene‐2 structure suggesting that the anomalous products may not be formed in a typical carbonium‐ion‐type rearrangement reaction but perhaps arise in a fission process associated with the propagation and/or transfer steps in the polymerization. With propylene as monomer the normal oligomers are by far the most important products, but all fission products can be detected.
Redox polymerization of acrylonitrile. Kinetics of the reaction initiated by the redox system tartaric acid–V5+
Authors: Mohanty T. R. , Singh B. C. , Nayak P. L.
Published: April 2003

Kinetics of vinyl polymerization of acrylonitrile initiated by the redox system tartaric acid–V5+ have been investigated in aqueous sulfuric acid in the temperature range 30–40°C. The rates of polymerization and V5+ disappearance and the chain lengths of polyacrylonitrile were measured. From the results it is concluded that the polymerization reaction is initiated by an organic free radical arising from the V5+–tartaric acid reaction with termination by V5+ ions. A suitable kinetic scheme has been proposed, and the various rate and energy parameters were evaluated.
The kinetics of styrene emulsion polymerization
Authors: Piirma Irja , Kamath V. R. , Morton Maurice
Published: April 2003

A study has been carried out on the kinetics of persulfate‐initiated emulsion polymerization of styrene in the presence of an anionic (oleate) or mixed anionic‐nonionic emulsifier. In both cases it appears that Smith‐Ewart kinetics are obeyed, i.e., there is a constant‐rate period up to 40–50% conversion, during which there is a concomitant constant molecular weight development. The sharp increases in molecular weight with conversion reported by Grancio and Williams appear to be an artifact resulting from the use of an impure emulsifier (Triton X‐100), which acts as a chain transfer agent to reduce the molecular weight by approximately an order of magnitude. Hence there does not appear to be any kinetic justification for assuming an inhomogeneous swollen latex particle (“core‐shell” morphology), and normal thermodynamic considerations should still apply to this swelling phenomemon.
Synthesis, mechanism, and property aspects of a new class of polyethers: Poly(1,4‐dichloro‐2,3‐epoxybutane)s
Authors: Vandenberg E. J.
Published: April 2003

Ring‐opening polymerization and copolymerization of the cis and trans isomers of 1,4‐dichloro‐2,3‐epoxybutane has let to an interesting 50% Cl. This family of polymers is expected to acquire commercial importance.
Effect of nonelectrostatic interactions on the macromolecular behavior of polyelectrolytes. III. Optical rotatory dispersion of PLL in water and aqueous‐organic mixtures
Authors: Beaumais Jacques , Fenyo Jean‐Claude , Muller Guy
Published: April 2003

We have investigated the optical rotatory dispersion of a stereo‐irregular polyelectrolyte when neutralized with alkaline and N‐tetraalkylammonium hydroxides, both in water and aqueousacetone mixtures.

The variations of the optical activity properties during the neutralization can be well related to potentiometric and viscosity measurements. They are interpreted by assuming two kinds of solvation of the chiral centers located on the main chain, to which two partial optical rotary dispersions (ORD) of opposite signs are associated. The observed optical activity changes and specifically the discontinuity occurring in the neutralization range where a conformational transition between a compact structure and a more extended one is initiated, are thus accounted for in terms of the corresponding changes in the state of solvation of chains.
Photopolymerization of acrylonitrile in the presence of substituted triphenyl phosphites
Authors: Taninaka Takumi , Ogawa Takeshi , Minoura Yuji
Published: April 2003

It was found that acrylonitrile was polymerized at 30°C by ultraviolet irradiation in the presence of triphenyl phosphite and its derivatives, namely m‐CH3, p‐C2H5, and p‐CH3 substituted triphenyl phosphites under conditions where acrylonitrile alone did not polymerize and phosphites did not undergo photolysis. The rate of polymerization in the presence of triphenyl phosphite and tri‐p‐tolyl phosphite was found to be proportional to the monomer concentration, the phosphite concentration, and the light intensity. From these results, it was thought that a donor–acceptor complex formed between phosphite and acrylonitrile which absorbed light and initiated the radical polymerization. In the photopolymerization of acrylonitrile with substituted triphenyl phosphites, the rate of polymerization increased with an increase in electron‐donating ability of substituent. From the plot obtained by use of Hammett's equation (log Rp/Rp0 = ρσ), the ρ value was found to be −1.0.
Anionic polymerization initiated by lithium diethylamide in organic solvents. II. Investigation of the polymerization of isoprene
Authors: Angood A. C. , Hurley S. A. , Tait P. J. T.
Published: April 2003

The polymerization of isoprene, initiated by lithium diethylamide has been investigated in the presence of a number of additives. Kinetic results are interpreted on the basis of simultaneous initiation and propagation reactions. The effect of additives, particularly diethyl either, has a profound effect on both the rate of initiation and propagation. The active centers are believed to be ion‐pairs with the lithium counterions solvated by both ether and monomer molecules, and the actual propagation reaction is believed to involve a rearrangement of the monomer, complexed to the lithium, and the growing polymeric chain.
Synthesis and chromatographic separation of poly(styrene‐b‐ethylene oxide)
Authors: Wesslén Bengt , Månsson Per
Published: April 2003

Styrene–ethylene oxide block copolymers prepared through anionic polymerization were successfully separated from the corresponding homopolymers by thin‐layer chromatography on cellulose on both an analytical and preparative scale.
Effects of substituted triphenyl phosphites on the radical polymerization of acrylonitrile
Authors: Taninaka Takumi , Ogawa Takeshi , Minoura Yuji
Published: April 2003

The radical polymerization of acrylonitrile in the presence of nuclear‐substituted triphenyl phosphites (p‐Cl, H, p‐CH3, p‐OCH3) initiated by α,α′‐azobisisobutyronitrile at 50°C was investigated. It was found that the rate of polymerization decreased at low concentrations of phosphite, but after reaching a minimum the rate increased again with further increase in the phosphite concentration in the case of all substituted triphenyl phosphites. Formation of a weak complex between phosphite as donor and acrylonitrile as acceptor was confirmed from the change in chemical shifts of vinyl protons to higher magnetic fields on NMR spectroscopy. From the results of continuous variation method using NMR spectra, the complex was found to be of the 1:1 type. The effects of substituted triphenyl phosphite on the rate of polymerization and the chain‐transfer reaction to substituted triphenyl phosphites are discussed on the basis of these results.
Synthesis and properties of polycondensation polymers from compounds with asymmetric functional groups
Authors: Korshak V. V. , Vinogradova S. V. , Vasnev V. A. , Markova G. D. , Lecae T. V.
Published: April 2003

The effect of conditions of polycondensation on the structure of polymers formed from monomers with symmetric and asymmetric functional groups by nonequilibrium polycondensation has been studied for the system with acceptor‐catalytic polyesterification of β‐hydroxyethyl ethers of bisphenols and terephthalic acid chloride in the presence of triethylamine. Polymers with statistical or regular arrangement of diol residues in the chain can be produced in such systems, depending on the way in which starting compounds are introduced in the reactor. A difference in the reactivity of functional groups in an asymmetric monomer is not sufficient to produce polycondensation polymers with a regular structure. Gradual introduction of the symmetric monomer is essential to yield polymers with predominant “head‐to‐head” (“tail‐to‐tail”) configurations. Some properties of the resulting polymers have been studied. Polymers with ordered residues of the asymmetric monomers in the macromolecules have higher softening temperatures and an increased tendency for crystallization than the statistic polymers.
Synthesis of poly‐L‐naphthylalanine and its secondary structure
Authors: Ueno Akihiko , Nohara Masao , Toda Fujio , Uno Keikichi , Iwakura Yoshio
Published: April 2003

Polypeptides derived from L‐naphthylalanine and γ‐benzyl L‐glutamate were prepared. Conformational properties in solution were investigated by circular dichroism (CD) and infrared spectra on the soluble copolymers, and the copolymers were assumed to take the right‐handed α‐helical conformation. By the addition of trifluoroacetic acid, a transition of side‐chain arrangement is induced simultaneously with the conformational transition of the peptide backbone for the copolymer with the highest content of L‐naphthylalanine residues. Fluorescence spectra of the copolymers show no excimer emission, which is evidence for the rigid orientation of the side‐chain naphthyl groups. The infrared spectrum and x‐ray diagram of poly‐L‐naphthylalanine do not rule out the helical conformation in the solid state.
Graft polymerization of vinyl monomers onto cellulose in presence of soda lime glass. I
Authors: Mansour Olfat Y. , Nagaty Ahmed
Published: April 2003

Sodium bisulfite–soda lime glass has proved to be a good initiator for polymerization and graft polymerization onto cellulose of some vinyl monomers. A scheme dealing with the mechanism of initiation has been proposed assuming trapping of the bisulfite radical inside the glass frame‐work to form a so‐called sulfur‐impregnated solid. Such a solid has paramagnetic properties and acts on the vinyl monomers and cellulose as any free‐radical‐producing source thus leading to polymerization and graft polymerization onto cellulose. Other radicals containing sulfur, such as sulfite, sulfate, and persulfate failed to give such property with soda lime glass. With the sodium bisulfite–soda lime glass system the reactivity decreases in the order methyl methacrylate > ethyl acrylate > acrylonitrile which is inconsistent with the arrangement of acceptor monomers with decreasing electron‐donating ability. This may reflect interference of the addition reaction which may take place between the monomer and bisulfite and the rate of which may depend on the activation energy of the monomer.
Thermal and radiation‐induced dehydrochlorination of poly(vinyl chloride). II. Head‐to‐head structures
Authors: Mitani Katsuo , Ogata Takayuki , Awaya Hiroshi , Tomari Yasuo
Published: April 2003

The mechanism of dehydrochlorination of 2,3‐dichlorobutane and chlorinated polybutadiene which are model compounds of head‐to‐head poly(vinyl chloride) has been investigated by pyrolysis, thermal, and ultraviolet‐induced decomposition. The activation energy of dehydrochlorination for head‐to‐head poly(vinyl chloride) in nitrogen was 23 kcal/mole at temperatures of 150–190°C, which is slightly smaller than that (29 kcal/mole) for head‐to‐tail poly(vinyl chloride). The conjugated double bonds were formed by thermal and radiation decomposition of head‐to‐head poly(vinyl chloride), similar to head‐to‐tail poly(vinyl chloride). The probability of polyene formation by radiation‐induced dehydrochlorination is larger than that by thermal decomposition and is affected by the conformation and the molecular motion of the main chain. This may be due to the alternative mechanism of dehydrochlorination in the thermal and radiation decomposition. The amount of head‐to‐head linkage of poly(vinyl chloride) samples prepared with various catalysts is dependent on polymerization temperature rather than the kinds of catalyst. Commercial poly(vinyl chloride) has 6–7 head‐to‐head linkages per 1000 monomeric units.
Esterification of polymeric carboxylic acids
Authors: Cohen H. L.
Published: April 2003

Polymers containing pendant carboxyl groups have been essentially completely esterified with little apparent change in molecular weight by the use of one of the following reagents: (1) trialkyl orthoesters, (2) dimethylformamide dialkyl acetals, (3) tertiary amines followed by alkyl halides, (4) quaternary ammonium hydroxide followed by alkyl halides. The use of some of these methods permits preparation of certain polymers that were previously not readily accessible.
Mechanism of oxidation at a copper–polyethylene interface. II. Penetration of copper ions in the polyethylene matrix
Authors: Allara D. L. , White C. W. , Meek R. L. , Briggs T. H.
Published: April 2003

Two surface analysis techniques (Rutherford backscattering and surface composition by analysis of neutral and ion impact radiation) have been applied to the study of interfacial copper transport in the oxidation of polyethylene films over copper surfaces. Analysis of films oxidized several thousand hours at 40, 57, and 87°C shows maximum concentrations of copper species in the polymer matrix of ∼0.1M extending to depths of several thousand angstroms. These results, together with previous infrared spectroscopic studies, allow some significant conclusions and hypotheses to be drawn as regards the roles of heterogeneous and homogeneous catalytic processes which occur in the thermal‐oxidative degradation of polyethylene–copper systems.
Emulsion copolymerization behavior of α‐methylstyrene with methacrylonitrile
Authors: Kenney J. F. , Patel P. J.
Published: April 2003

The emulsion copolymerization behavior of α‐methylstyrene with methacrylonitrile is described. The effects of polymerization temperature, potassium persulfate initiator concentration, sodium lauryl sulfate emulsifier concentration on copolymer yield, molecular weight, and rate of copolymerization are described. The copolymer was found to have an azeotropic composition at 43 mole‐% AMS. Reactivity ratios were determined to be 0.06 and 0.28 for AMS and MAN, respectively.
Study of radiation‐induced polymerization of vinyl monomers adsorbed on inorganic substances. V. Effects of p‐benzoquinone and dose rate on methyl methacrylate–silica gel system
Authors: Fukano Kazuyuki , Kageyama Eiichi
Published: April 2003

In order to elucidate the mechanism of radiation‐induced polymerization of methyl methacrylate adsorbed on silica gel, the effects of p‐benzoquinone addition and dose rate were studied in detail. Most of the polymerization is inhibited by p‐benzoquinone at levels above 10‐2 mole/l. The GPC spectra of both graft polymers and homopolymers show two peaks. The high molecular weight material appears to have been formed by polymerization by a radical mechanism, because these peaks decrease as p‐benzoquinone concentration increases; on the other hand, their low molecular weight polymers seem to be products of an ionic polymerization mechanism because those peaks are almost not affected by p‐benzoquinone. The four GPC peaks differ in dose rate dependences of their polymerization rate. The dose‐rate exponents of polymerization rate were obtained for the four GPC peaks. The behavior of the low molecular weight peaks of graft polymers and homopolymers were quite different, suggesting that the polymers differ considerably in formation mechanism.
Synthesis of polypropionamide‐ureas from N‐mesyloxysuccinimide and diamines
Authors: Imai Yoshio , Ueda Mitsuru , Ishimori Motokazu
Published: April 2003

A series of polypropionamide‐ureas was synthesized by the polymerization of N‐mesyloxysuccinimide with diamines in polar aprotic solvents in the presence of acid acceptors. The polymerization proceeded through the formation of ring‐opened adducts, followed by elimination and rearrangement yielding β‐isocyanatopropionamide derivatives, which in turn were polymerized to afford polypropionamide‐ureas. These polymers had inherent viscosities in the range of 0.1–0.2. Polymers having aliphatic chains which were fusible below 240°C were soluble in acidic solvents, whereas those with aromatic residues dissolved in polar aprotic solvents. Marked decomposition of the polyamide‐ureas under thermogravimetric analysis generally occurred at around 320°C under nitrogen.
Photopolymerization via the Paterno‐Büchi reaction. I. Reaction of aromatic diketones with tetramethylallene
Authors: Andrews D. J. , Feast W. J.
Published: April 2003

Aromatic diketones of the benzophenone type undergo photopolymerization on irradiation at 350 nm with tetramethylallene in benzene solution. The polymers produced contain oxetane units in the main chain, and spectroscopic analysis demonstrates that the distribution of structural units parallels that found in the reaction between benzophenone and tetramethylallene. The polymers are rapidly degraded thermally and by mineral acids.
Copolymerization of styrene with vinyltriethoxysilane and vinyltriacetoxysilane
Authors: Bajaj P. , Khanna Y. P. , Babu G. N.
Published: April 2003

Styrene was copolymerized in bulk with vinyltriethoxysilane at 80°C and vinyltriacetoxysilane at 60, 80, and 100°C with the use of benzoyl peroxide as an initiator at low conversions. Copolymer composition was determined from the silicon content and reactivity ratios were calculated by the conventional scheme of copolymerization. The low r1 value (styrene) in the styrene‐vinyltriacetoxysilane system (St–VTAS) as compared to styrene‐vinyltriethoxysilane (St–VTES) copolymerization may be attributed to higher reactivity of VTAS towards the polystyryl radical. Further, in the St–VTAS system, r1 tends to decrease with increasing polymerization temperature. The influence of silicon comonomer on properties of the copolymers (intrinsic viscosity, solubility, dielectric and thermal behavior) was studied.
Chemorheology of linear polymers. II
Authors: Murakami Kenkichi , Nakanishi Hiromasa
Published: April 2003

The chemical stress relaxation of crosslinked polymers had long been studied. The chemorheology of linear polymers is difficult to study because molecular flow by diffusion is generally much more rapid than relaxation or flow caused by chemical reaction. Our previous paper dealt with the chemorheology of linear polymers on taking such physical flow into consideration. By using another modified expression suggested by Tobolsky, good consistency between the theoretical chemical stress relaxation curve and an experimental one was obtained for polydisperse polystyrene and the commercial polystyrene used.
Polystyrene degradation induced by stresses resulting from the freezing of its solutions
Authors: Abbas Kent B. , Porter Roger S.
Published: April 2003

Solutions of polystyrene in p‐xylene were frozen in liquid nitrogen. No changes in molecular weight and distribution were caused by freezing solutions for a series of narrow distribution polystyrenes with molecular weights of near 2 × 106 and lower. Likewise a commercial polystyrene of M̄w = 234,000 showed no change, even after 45 cycles of freezing and thawing. However, an ultrahigh molecular weight polystyrene (M̄w = 7.3 × 106) showed appreciable degradation even after a few freezing cycles of its solutions. The changes in molecular weight and distribution were analyzed by gel‐permeation chromatography. The results depended very much on the choice of solvent, cooling rate, and concentration. The extent of degradation was found to depend on polymer concentration in two distinct ways. Indeed, two different degradation mechanisms have been distinguished at low and at high concentrations. The change between mechanisms took place between 1.0 and 2.5 g/l. for polystyrene in p‐xylene. This appears to provide a rare measure of polymer‐polymer interactions (entanglements) in dilute solutions. Degradation in the entanglement region proceeded via a random chain‐scission mechanism as tested by the Scott method. In contrast, at low concentrations degradation was characterized by the formation of appreciable amounts of low molecular weight polystyrene. The presence of an antioxidant (Ionol) during freezing did not change the extent of degradation significantly.
Anionic polymerization. III. Polymerization of butadiene with alkali metal alkoxide‐modified alkali metal system
Authors: Cheng Tai Chun , Halasa Adel Farhan
Published: April 2003

A high molecular weight polybutadiene was prepared in hexane solvent by using alkali metal (Li, Na, K) and metal tert‐butoxide (Li, Na, K) as a polymerization initiator. The microstructure of polybutadiene varies, depending on the type of modifiers and polymerization and temperatures. The results and mechanistic implications of this study are discussed.
Synthesis of polybenzodipyrrolediones by thermal cyclodehydration of polyamides derived from dibenzylidenebenzodifurandiones and aliphatic diamines
Authors: Ueda Mitsuru , Takahashi Takeyoshi , Imai Yoshio
Published: April 2003

A new class of polyheterocycles, polybenzodipyrrolediones (PBP), has been synthesized successfully by the two‐step polymerization of dibenzylidenebenzodifurandiones with aliphatic diamines. New bislactone monomers, 3,5‐dibenzylidene‐3,5‐dihydro‐1H,7H‐benzo[1,2‐c:4,5‐c′]difuran‐1,7‐dione and 3,7‐dibenzylidene‐3,7‐dihydro‐1H,5H‐benzo[1,2‐c:4,5‐c′]‐difuran‐1,5‐dione, were synthesized from pyromellitic dianhydride and phenylacetic acid. The ring‐opening polyaddition reaction of the bislactones with aliphatic diamines in a polar solvent afforded novel polyamides having inherent viscosities of 0.1–1.0 in quantitative yield. The solution polymerization was almost completed within several hours at 80°C, while it required approximately a week to its completion at room temperature. Dimethyl sulfoxide and N‐methyl‐2‐pyrrolidone were preferred solvents for the polymerization. The open‐chain polyamides were subsequently cyclodehydrated by heating at 240°C to give PBP having high molecular weight. The aliphatic PBP were soluble in hot polar solvents such as N‐methyl‐2‐pyrrolidone, m‐cresol, and nitrobenzene. They began to decompose at about 400°C in a nitrogen atmosphere as determined by thermogravimetric analysis.
Degradation of polymer mixtures. VII. Blends of poly(vinyl acetate) with polystyrene
Authors: Jamieson A. , McNeill I. C.
Published: April 2003

The degradation of films containing both PVA and PS has been investigated for comparison with the behavior already reported for PVC/PS blends. The presence of PS had little, if any, effect on the behavior of PVA, but PVA had an effect similar to that of PVC on the degradation of PS. Styrene production was retarded in the blend, compared to PS alone, and an increase in the rate of chain scission was observed for a high molecular weight sample. The molecular weight effect, however, was much smaller than in corresponding experiments with PVC/PS blends. Interference with intermolecular transfer in PS is again advanced as the probable explanation of the stabilization of PS.
ESR study of linear aliphatic oligoesters under γ‐irradiation. I. Paramagnetic species produced in the material by irradiation at 77°K
Authors: Ooi Toshitami , Mimura Koji , Hama Yoshimasa , Shinohara Kenichi
Published: April 2003

Paramagnetic species produced in a series of linear aliphatic oligoesters $ [\bond;{\rm O}\bond;({\rm CH}_{\rm 2} {\rm )}_m\bond;{\rm O}\bond;{\rm CO}\bond;({\rm CH}_{\rm 2} {\rm )}_n\bond;{\rm CO\rlap{--} ]}_P $ by γ‐irradiation at 77°K was investigated by an ESR method. A predominant doublet observed immediately after γ‐irradiation, which has hyperfine splitting of 20–23 gauss, is attributed to a radical anion III.
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Slight decay of this radical anion is observed by illuminating the sample with visible light at 77°K. A small amount of the radical anion is converted to double triplet, which is assigned to (ES)CHCH2 (where ES denotes the ester group), from the result of heat treatment. The conformational angles for the two β‐protons in the (6,2) oligoester are determined to be θ1 = θ2 = 30°.
Effect of nonpolar field formed by polymer ligand on the oxidation of 2,6‐xylenol catalyzed by Cu complexes
Authors: Tsuchida Eishun , Nishikawa Hiroshi , Terada Eiichi
Published: April 2003

The oxidative polymerization catalyzed by Cu(II)‐poly(vinylpyridine) derivatives and the effect of the nonpolar field formed by the polymer ligand on the catalysis was studied in dimethyl sulfoxide (DMSO) solvent. The catalytic activity of the Cu complex increases in the following order; Cu‐(styrene‐vinylpyridine copolymer) (St·VP) complex > Cu‐partially quarternized (by benzyl chloride) poly(vinylpyridine)(BCQP) complex > Cu‐poly(vinylpyridine) (PVP) complex > Cu‐pyridine (Py) complex > Cu‐partially quarternized (by ethyl bromide) poly(vinylpyridine) (EBQP) complex. This order is the same as that of the reoxidation rate constant of the catalyst. Acceleration of ko process in Cu‐St>VP and Cu‐BCQP systems, where the active site is in the nonpolar field formed by the polymer ligand, is explained by an increase in strength of the coordination bonds.
Sulfur‐containing vinyl monomers. XIII. Cationic copolymerizations of vinyl sulfides with some vinyl monomers
Authors: Inoue Hiroshi , Otsu Takayuki
Published: April 2003

Cationic copolymerizations of vinyl sulfides (VS) with some vinyl monomers with boron tri‐fluoride‐diethyl etherate catalyst were investigated to evaluate their monomer reactivities. The effects of VS on the copolymer yield and viscosity of the resulting copolymers revealed the inhibition or retardation mechanism which was explained in terms of the formation of a stable vinylsulfonium salt by the reaction between a propagating carbonium ion and VS monomer. From the results of copolymerizations of phenyl vinyl sulfide (PVS) with isobutyl vinyl ether (IBVE), β‐chloroethyl vinyl ether (CEVE), α‐methylstyrene (α‐MeSt), and styrene (St), the relative reactivities of these monomers were found to be in the following order: IBVE > CEVE > PVS > α‐MeSt > St. The relatively higher reactivity of PVS than St derivatives was explained on the basis of the conjugative and electron‐donating nature of the VS monomer. The effects of alkyl and para‐substituted phenyl groups in vinyl sulfides on their reactivities toward the propagating carbonium ion were correlated with polar factors and compared with those of the hydrolysis of α‐mercaptomethyl chlorides. The transition state for the propagation reaction in cationic polymerization of VS was proposed to be a π‐complex type structure.
Electrical properties of poly‐trans‐2,5‐dimethylpiperazine‐fumaramide. I.D.c. Conductivity by a new instrumentation
Authors: Sandrolini F. , Manaresi P.
Published: April 2003

The d.c. conductivity of a recently synthesized polyamide, poly‐trans‐2,5‐dimethylpiperazine‐fumaramide, was investigated by a new instrumentation designed for measuring very low conductivity in insulating materials over broad ranges of temperature and environmental conditions. The instrumentation system allows measurements based on the voltmeter‐ammeter method according to ASTM D‐257, under atmospheres from high vacuum to a pressure of several times atmospheric of the desired gas and at temepratures from room to about 300°C, with an overall accuracy usually better than 10%. The material was examined in form of powder as well as film, in the dry and hydrated state, usually under vacuum up to about 200°C. The polymer behaves as an insulating material and exhibits a great increase in conductivity with water content. The results obtained do not permit a detailed discussion of the actual conduction mechanism. Although it seems to be primarily electronic in nature, an ionic contribution increasing with temperature cannot be excluded. There is no protonic contribution to the conduction because of the absence of N‐H groups in the molecular chains.
Cleavage of poly(vinyl alcohol) in the presence of tert‐butyl hydroperoxide and biologically active metal complexes
Authors: Jochsberger T. , Auerbach A. , Indictor N.
Published: April 2003

The cleavage of poly(vinyl alcohol) in dimethyl sulfoxide at 42°C has been measured viscometrically in the presence of tert‐butyl hydroperoxide and metal complexes. Phthalocyanine complexes of copper(II), iron(III), cobalt(II), and vanadium as VO(II) as well as hemin, hematin, chlorophyllin, and cytochrome c were used. The rates of decomposition of tert‐butyl hydroperoxide in the presence of these metal complexes were measured idometrically. These data are compared to results obtained with other metal complexes in similar reactions.
Cyclopolymerization. V. Monomer design for the synthesis of highly cyclized polymer from unsymmetrical unconjugated dienes: Synthesis and polymerization of N‐methyl‐N‐allylmethacrylamide
Authors: Kodaira Toshiyuki , Ishikawa Masaki , Murata Osamu
Published: April 2003

N‐Methyl‐N‐allylmethacrylamide (MAMA) was synthesized and polymerized with radical initiators, and the structure of poly‐MAMA was studied, in order to establish the concept that difunctional monomers having monofunctional counterparts which do not polymerize are likely to give rise to highly cyclized polymer, if the cyclized polymer is in a lower free‐energy level than the monomer. The cyclopolymerizability of MAMA was considerably higher than that of N‐allylmethacrylamide, which was previously reported, and its monofunctional counterpart can be polymerized. The extent of cyclization of poly‐MAMA was about 93%, even in the polymer obtained by bulk polymerization. The repeating units of poly‐MAMA consist mainly of five‐membered rings; six‐membered rings and pendent methacryl groups were detected in addition as minor repeating components. The monofunctional counterparts of MAMA, i.e., N‐methyl‐N‐n‐propylmethacrylamide (MPMA) and N‐methyl‐N‐allylisobutyramide (MAIA), were also synthesized. Neither MPMA nor MAIA showed any tendency toward polymerization under the same experimental conditions as used for MAMA. The results thus obtained all support the concept mentioned above.
Synthesis of polyamides by ring‐opening polyaddition of benzobis[1,2]oxazinediones with aliphatic diamines
Authors: Ueda Mitsuru , Hazome Hisashi , Imai Yoshio
Published: April 2003

Novel oxime‐containing polyamides have been prepared by the ring‐opening polyaddition of combinations of two benzobis[1,2]oxazinediones, 4,6‐diphenylbenzo[1,2‐d:5,4‐d′]bis[1,2]oxazine‐1,9‐dione and 4,9‐diphenylbenzo[1,2‐d:4,5‐d′]bis[1,2]oxazine‐1,6‐dione, with two aliphatic diamines in a polar aprotic solvent such as N‐methyl‐2‐pyrrolidone. The polymerization was almost completed within a day at room temperature. These polymers had inherent viscosities in the range of 0.12–0.38 and were soluble in a wide range of solvents, including formic acid and hot m‐cresol, as well as a number of polar aprotic solvents. All the polymers softened at a temperature ranging from 165 to 185°C. Thermal characterization of the polyamides by TGA and DTA showed polymer decomposition temperatures of about 240°C in air.
Polyamides from perchloro‐4,4′‐dichloroformylbiphenyl
Authors: Escobar H. , Díaz F. R. , Ramíarez R. S.
Published: April 2003

New thermally stable polyamides were prepared by low‐temperature polycondensation in N,N‐dimethylacetamide from perchloro‐4,4′‐dichloroformylbiphenyl and various aromatic and aliphatic diamines. The polymers were characterized by infrared spectroscopy, elemental analysis, TGA, and DSC and found to show higher thermal stability than other nonchlorinated polyamides.
Effect of solvent in radical polymerization of butadiene 1‐carboxylic acid
Authors: Bando Yoshihumi , Minoura Yuji
Published: April 2003

The radical polymerization and copolymerization of butadiene 1‐carboxylic acid (Bu‐1‐Acid) were studied in a variety of the electron‐donor solvents such as dimethylformamide (DMF), tetrahydrofuran (THF), methyl ethyl ketone (MEK), acetonitrile (ACN), and benzene (BZ) using AIBN as an initiator at 50°C. Under these conditions, the polymerization rate of Bu‐1‐Acid increased in the order, DMF < THF < MEK < ACN < BZ in the various solvents. In copolymerization with styrene [M2] and acrylonitrile [M2], the monomer reactivity ratio r1 increased and r2 decreased in the same order. Moreover, it was found that Alfrey‐Price Q‐e value of Bu‐1‐Acid increased depending on solvent in the order DMF < THF < MEK < ACN < BZ. These variations were correlated to the electron‐donating power (Δvcm−) of the solvents used and are discussed on the basis of the solvation of Bu‐1‐Acid into the solvent. Also, it was found that the microstructures of these polymers were always trans‐1,4 and did not change with the solvent used.
Effect of pH on radical polymerization of butadiene 1‐carboxylic acid in aqueous solutions
Authors: Bando Yoshihumi , Minoura Yuji
Published: April 2003

Radical polymerization of butadiene 1‐carboxylic acid (Bu‐1‐Acid) was carried out in aqueous solutions at 50°C with ammonium persulfate (APS) as an initiator. Kinetic studies led to the rate equation, Rp = k[APS]1/2 [Bu‐1‐Acid]1 at pH 6.8. The overall activation energy for the polymerization was 16.0 kcal/mole. The polymerization rate Rp of Bu‐1‐Acid decreased with an increase of pH in the range 2.4–6.8 and increased with an increase of pH in the range 6.8–8.4. Moreover, in the pH range 8.4–13, the rate of polymerization was not affected by the pH of the system. In copolymerization with acrylonitrile, the trends of changes in the monomer reactivity ratios r1, r2 and Q‐e values caused by changes in pH were similar to trends found in homopolymerization described above. In addition, it was observed that the resultant polymer was extended in alkaline solution and contracted in acidic solution.
ESR study of radiation‐induced polymerization of methyl methacrylate on solid surfaces
Authors: Yoshioka Hisashi , Matsumoto Hidenobu , Uno Shinpey , Higashide Fukuji
Published: April 2003

ESR spectra of methyl methacrylate (MMA) adsorbed on solid surfaces such as silica, alumina, and CPG‐10 show a seven‐line absorption due to monomer radicals when γ‐irradiated at −196°C. These spectra turn into conventional nine‐line spectra by annealing at −86°C as a result of polymerization. The intensity ratio of the four‐line component to the five‐line component changes with further polymerization. The ratio depends on the kind of solid and the smallest value is obtained in the spectra of alumina‐MMA. The temperature of irradiation strongly affects the value in alumina‐MMA. These results suggest that MMA is strongly adsorbed and deformed the conformation on alumina surface.
Polymerization initiated by an electron donor–acceptor complex. VI. Polymerization of methyl methacrylate initiated by a liquid SO2–nicotine complex and carbon tetrachloride
Authors: Matsuda Minoru , Ishioroshi Yasuhiro , Seki Kiichiro
Published: April 2003

A kinetic study has been made of polymerization of methyl methacrylate initiated by an electron donor–acceptor complex of liquid SO2 (electron acceptor) and nicotine (donor) in the presence of carbon tetrachloride. It is concluded that the polymerization proceeds through free‐radical intermediates similar to the cases of liquid SO2–pyridine and liquid SO2–poly(2‐vinylpyridine) complexes. The overall rate of polymerization is proportional to the square root of both liquid SO2 and nicotine concentrations, and the values of kp/kt½ under various polymerization conditions are in satisfactory agreement with the literature values. For the activation energy of initiation, 13.6 kcal/mole is estimated from the kp/kt½ values obtained at temperatures ranging from 0 to 80°C.
Hydrogen‐transfer polymerization of methyl‐substituted acrylamides
Authors: Otsu Takayuki , Yamada Bunichiro , Itahashi Masaki , Mori Takashi
Published: April 2003

Base‐catalyzed hydrogen‐transfer polymerization and copolymerization of acrylamide and its methyl‐substituted derivatives were studied in pyridine at 110°C. n‐Butyllithium was used as an initiator. The observed rates of these homopolymerizations were found to decrease in the following order: acrylamide > crotonamide > methacrylamide > N‐methylacrylamide > N‐methylcrotonamide > tiglinamide > N‐methylmethacrylamide ≫ α‐chlorocrotonamide ≃ α‐cyanocrotonamide = 0. Acrylamide gave the polymer with the highest degree of polymerization among the monomers examined. It was found that the number and the position of the methyl substituent in acrylamide affected significantly both the rate of polymerization and the molecular weight of the polymer. Although all polymers obtained, except the N‐methyl derivatives, contained both methanol‐soluble and methanol‐insoluble fractions, a polyamide structure with unsaturated terminal monomer unit was confirmed by both infrared and NMR determinations. From the NMR determination of the saturated and terminal unsaturated units, the degree of polymerization of the resulting polyamides were also obtained. The monomers were also found to copolymerize by a hydrogen‐transfer mechanism. However, the main chain of the resulting copolymers was composed of the more reactive monomer unit, and the less reactive monomer was incorporated only as a terminal unit when a less reactive monomer was copolymerized with a more reactive one. From these results, it was concluded that these polymerizations proceeded via an intermolecular hydrogen‐transfer mechanism (i.e., stepwise mechanism).
Amide‐exchange reactions in mixtures of N‐alkyl amides and in polyamide melt blends
Authors: Miller I. K.
Published: April 2003

The amide‐exchange reactions which cause copolymer formation in polyamide melt blends were studied with mixtures of N‐ethylcaproamide and N‐hexylacetamide containing small concentrations of caproic acid and hexylamine as a model system for melt blends of aliphatic polyamides. Amide exchange was found to involve acidolysis and aminolysis reactions with no detectable contribution of direct reaction between amide groups. Kinetics data are consistent with formation of an anhydride intermediate in amide acidolysis. Rate constants over the range 200–275°C and activation energies for amide acidolysis and aminolysis reactions are given. Equations are given for calculating amide exchange rates in polyamide melt blends and for relating degree of amide exchange to block copolymer composition.
Preparation and properties of polyamides and polymides containing bibenzyl, stilbene, and tolan structures
Authors: Inoue Kazuto , Imai Yoshio
Published: April 2003

Polyisophthalamides and polyterephthalamides were prepared by the solution polycondensation of the corresponding diacyl chlorides with 4,4′‐diaminobibenzyl, trans‐4,4′‐diaminostilbene, and 4,4′‐diaminotolan in N,N‐dimethylacetamide (DMAc). Polypyromellitimides were synthesized in two steps by the ring‐opening polyaddition of pyromellitic dianhydride with the aromatic diamines in DMAc, followed by thermal cyclodehydration. The amorphous polyisophthalamides were soluble in some amide solvents containing lithium chloride, while the polyterephthalamides having fair degree of crystallinity were insoluble in these solvents. The thermal stability of these aromatic polymers decreased in the order of the tolan‐containing polymers > the stilbene‐containing polymers > the bibenzyl‐containing polymers, both in air and under nitrogen.
ESR study on photodecomposition mechanism of oxidized poly(vinyl alcohol)
Authors: Yasunaga Toshio , Kubota Hitoshi , Ogiwara Yoshitaka
Published: April 2003

Photolysis behavior of oxidized poly(vinyl alcohol) (PVA) in which carbonyl groups were introduced by oxidation with sodium hypochlorite and periodic acid was investigated by using ESR spectrometry. Increased formation of PVA radicals was observed in the sample with low degree of oxidation, which showed an emphasized formation of triplet component radical. On the other hand, the formation of radicals tended to be depressed in the highly oxidized sample, and a singlet component was dominant in the ESR spectrum. By examining infrared and ultraviolet spectra of the oxidized sample, the sample was found to contain two structures, a saturated ketone group and an α,β‐unsaturated group; the latter structure was intensified with increasing degree of oxidation. Based on ESR studies of the photoirradiated acetone and mesityl oxide, the models of saturated and α,β‐unsaturated ketone structures in the oxidized PVA, respectively a photodecomposition mechanism of oxidized PVA was proposed.
Multiblock copolymers of styrene and isoprene. I. Synthesis and characterization
Authors: Corbin N. , Prud'Homme J.
Published: April 2003

An anionic polymerization procedure for preparing multiblock copolymers of styrene and isoprene is described. The process is based on the initial specific incorporation of isoprene when mixtures of styrene and isoprene are polymerized with butyllithium in hydrocarbon solution. As examples, linear (AB)3 block copolymers have been prepared by interrupting styrene polymerization by step additions of isoprene at times programmed according to the reactivity ratios and the rate constants for styrene and isoprene propagations. The products were characterized by means of osmometry, light scattering, gel‐permeation chromatography, and density‐gradient ultracentrifugation. The analyses showed that the multiblock copolymers are free from polymeric impurities and reasonably homogeneous in molecular weight and composition. The polystyrene segment lengths were analyzed by means of GPC after the oxidative degradation of the polyisoprene moieties in the copolymers. The results suggest that the polyisoprene blocks contain a nonnegligible amount of styrene but that this monomer is incorporated as very short segments. On the other hand the polystyrene blocks produced at the end of the copolymerizations appear to have narrow molecular weight distributions.
Chemical modification of polymers. VII. Condensation of polymeric aldehydes with the anion of an isoquinoline reissert compound
Authors: Gibson Harry W. , Bailey F. C.
Published: April 2003

The anion of the isoquinoline Reissert compound, 2‐benzoyl‐1,2‐dihydroisoquinaldonitrile, reacts with polymeric aldehydes in essentially complete conversion, leading to polymeric esters containing isoquinoline moieties. These can be completely hydrolyzed to the corresponding alcohols. The reactivity of the Reissert anion toward polymeric halides and aldehydes is rationalized on the basis of its moderate hardness.
Oxysilane polymers from silanediol–bisdimethylaminosilane polycondensations: Synthesis and properties
Authors: Pittman Charles U. , Patterson William J. , McManus Samuel P.
Published: April 2003

The solution polycondensation of 1,4‐bis(hydroxydimethylsilyl)benzene with six bis(dimethylaminosilanes) was carried out by the aminosilane deficient method to give a series of high polymers. The bis(dimethylaminosilanes) were bis(dimethylamino)dimethylsilane, bis(dimethylamino)methylphenylsilane, bis(dimethylamino)diphenylsilane, 1,4‐bis(dimethylaminodimethylsilyl)benzene, 1,3‐bis(dimethylamino)‐1,1,3,3‐tetramethyldisiloxane, and 1,5‐bis(dimethylamino‐1,1,3,3,5,5‐hexamethyltrisiloxane). The condensation of dihydroxymethylphenylsilane with bis‐(dimethylamino)methylphenylsilane to give polymethylphenylsiloxane was also performed. A detailed description of the monomer syntheses and polymerization reactions is provided, since this paper represents the first detailed and systematic description of this polycondensation as an alternative to disilanol or disilanol‐dichlorosilane condensation routes. The thermal properties (i.e., Tg, TGA, DSC) of poly(p‐phenylenetetramethylsiloxane) are compared to those of poly[1,4‐bis(oxydimethylsilyl)benzenel] (where a Si(Me)2O group has been inserted between the silylphenylene units) as well as others in this series, polydimethylsiloxane, and polymethylphenylsiloxane. Similarly, these properties are compared with those of related polymers which include in‐chain ferrocene units. Introduction of Si(Me)2O units into poly(tetramethyl‐p‐silylphenylenesiloxane) systematically decreases Tg and thermal stability. Replacing SiCH3 with SiC6H5 groups increases Tg and thermal stability. Replacing in‐chain C6H4 with ferrocene increases Tg and slightly decreases thermal stability. The values of K and A in the Mark‐Houwink equation were determined for several polymers.
Theory of stabilizing thermally stable polymers
Authors: Gladyshev G. P.
Published: April 2003

It has been discovered that chemical compounds generated in some polymeric samples or articles and possessing high activity in the reactions with oxygen and free radicals as well as yielding inert products in the above reactions may stabilize the polymeric materials by inhibiting oxidative (and even thermal) degradation. The phenomenon described has both theoretical and experimental evidence.
Polymerization of N‐vinylcarbazole. II. Kinetic studies on polymerizations involving azoisobutyronitrile and benzoyl peroxide
Authors: Bevington J. C. , Dyball C. J.
Published: April 2003

The polymerization of N‐vinylcarbazole at 60°C in benzene has been initiated with azoisobutyronitrile, benzoyl peroxide, and their mixtures. The kinetics indicate that the azonitrile and the peroxide promote polymerizations of fundamentally different types. The resulting polymers have been examined by gel‐permeation chromatography. The polymer produced with benzoyl peroxide contains a small amount of a high molecular weight fraction which, from the point of view of end groups, resembles the polymer made by use of the azonitrile. It is concluded that benzoyl peroxide in this system gives rise to two types of polymerization which occur simultaneously.
Monomer‐isomerization polymerization. XVI. Monomer‐isomerization polymerization of methylpentenes with Ziegler‐Natta catalyst
Authors: Endo Kiyoshi , Otsu Takayuki
Published: April 2003

The polymerizations of 4‐methyl‐1‐pentene(4M1P), 4‐methyl‐2‐pentene (4M2P), 2‐methyl‐2‐pentene (2M2P), and 2‐methyl‐1‐pentene (2M1P) with Ziegler‐Natta catalyst have been investigated. Both 4M1P and 4M2P were found to polymerize with TiCl3–(C2H5)Al catalyst to give high molecular weight poly(4M1P), while 2M2P and 2M1P did not give polymers with 4M1P units. However, when the polymerizations of 2M1P and 2M2P were carried out with ternary catalyst systems, TiCl3–(C2H5)AlCl–(PPh3)2PdCl2 and TiCl3–(C2H5)AlCl–Ni(SCN)2 polymers with 4M1P units were obtained in low yield. It was concluded that these four methylpentenes could polymerize with the monomer‐isomerization polymerization mechanism to poly(4M1P). The results of the observed isomer distribution of methylpentenes recovered, and the rate of polymerization of four methylpentenes suggest that the isomerization from 2M1P to 4M1P with the above ternary catalyst systems might proceed via a direct one‐step isomerization mechanism.
Photochemistry of ketone polymers. XII. Studies of ring‐substituted phenyl isopropenyl ketones and their styrene copolymers
Authors: Sugita K. , Kilp T. , Guillet J. E.
Published: April 2003

The synthesis of a number of ring‐substituted phenyl isopropenyl ketones and their polymerization with styrene is reported. The ultraviolet absorption spectra of the polymers are analogous to those of ring‐substituted acetophenones and valerophenones. The quantum yields of the Norrish type II photoreaction were estimated in 1,2‐dichloroethane solution at 364 nm by automatic viscometry. These quantum yields are comparable to those of substituted butyrophenones and valerophenones, in that relatively high quantum yields were obtained for the unsubstituted and p‐chloro‐substituted compounds with low yields for p‐amino and p‐hydroxy compounds. The p‐nitro‐substituted compound gives no type II reaction, presumably because the excitation becomes localized on the nitro groups which photolyzes by a mechanism which does not involve chain scission. The implications of these studies on possible applications to photoimaging are discussed.