bluuebunny/crossref_metadata_2025_split huggingface dataset:
The solubility of cellulose in liquid ammonia/salt solutions
Authors: Hudson Samuel M. , Cuculo J. A. 
Published: April 2003

AbstractThe dissolution of cellulose in solutions of liquid ammonia and ammonium thiocyanate is discussed. Viscosity measurements on dilute solutions of cellulose in this solvent over a range of shear rates and shear stresses are reported. A four‐bulb Ubbelohde suspended level viscometer was used for the measurements. Plots of log [η] versus log M gave Mark‐Houwink coefficients of a = 0.95 and K = 6.686 × 10−5 at 25°C for [η] as dl/g. The Bloomfield equation was used to calculate effective bond lengths (b) from limiting viscosity numbers of cellulose in solutions of ammonia/ammonium thiocyanate and Cuene, respectively. Results indicate that cellulose may have similar configurations in both solvents and also that the ammonia solutions are true cellulose solutions. Miscibility of the cell‐ ulose/ammonia/ammonium thiocyanate solutions with organic solvents, such as glycerol, is also reported. Further, a few interesting characteristics of the liquid ammonia/ammonium salt solutions, discussed briefly, are the convenient boiling point, the rheological behavior, and the relatively high concentration of cellulose obtainable.
Polymerization of aromatic nuclei. XXVI. Poly(p‐phenylene): Friedel–crafts alkylation, molecular weight, and propagation mechanism
Authors: Jones Martin B. , Kovacic Peter , Lanska Douglas 
Published: April 2003

AbstractPoly(p‐phenylene) was alkylated with n‐propyl bromide, n‐propyl chloride, and isopropyl bromide in the presence of aluminum chloride. Apparently, the reactions involve dialkylation with n‐propyl halides and alternating mono‐ and dialkylation with isopropyl bromide. Alkylation with ethyl or n‐butyl bromide was unsuccessful. The dialkylated polymer was sufficiently soluble to allow molecular weight determination. Mechanistic aspects of alkylation and propagation are treated.
Studies on the vinyl polymerization photoinitiated by p‐benzoylperoxybenzoic acid tert‐butylester
Authors: Gupta Satyendra N. , Gupta Ipsita , Neckers D. C. 
Published: April 2003

Abstractp‐Benzoylperoxybenzoic acid tert‐butylester (BPE) undergoes an efficient photodecomposition producing cleavage of the peroxy bond. The excited triplet benzophenone carbonyl group of the perester is quenched by vinyl monomers (the degree of which depends on the type of monomer used) thus reducing the rate of decomposition of BPE when it is used as a photoinitiator. Radicals generated from the decomposition of BPE are highly efficient in initiating vinyl polymerization. The benzophenone‐containing end groups of the polymer chain can be estimated and the carbonyl function is useful for polymer modification.
Synthesis of aromatic polyamides having pyridine moiety and their lyotropic properties in solution
Authors: Ogata Naoya , Sanui Kohei , Koyama Takashi 
Published: April 2003

AbstractFully aromatic polyamide containing pyridine moieties (PPy) were successfully synthesized either by interfacial or solution polycondensation to prepare polyamide with inherent viscosity as high as 4. Solution properties of PPy in sulfuric acid were investigated in terms of solution viscosity and lyotropic behavior. The polyamide had a better solubility in sulfuric acid than in poly(p‐phenylene terephthalamide) (PT) and the PPy solution in sulfuric acid exhibited an optically anisotropic property in a wider range of concentrations at relatively low temperatures in comparison with the PT solution. Viscosities of the PPy solution and the film cast from the PPy solution indicated a phenomenon characteristic of a highly oriented rigid polymer molecule caused by a lyotropic behavior.
The synthesis of a macromolecular ligand by the modification of polystyrene
Authors: Phillips Hodge H. , Kinstle James F. , Adcock James L. 
Published: April 2003

AbstractUncrosslinked atactic polystyrene was chemically modified first by acetylation then by a Claisen condensation with ethyl perfluoropropanoate to produce three crosslinked chelating polymers that contained a phenyl, perfluoroethyl, beta‐diketone chelating group in 10, 20, and 63 mole % compositions. Cu(II), Ni(II), and uranyl chelates of the macromolecular ligands were prepared and analyzed. The macromolecular ligands and their chelates were compared with the model ligating species 4,4,5,5,5‐pentafluoro‐1‐phenyl‐1,3‐pentanedione with infrared and mass spectroscopy and proton nuclear magnetic resonance.
Electron transfer reactions to electroactive polymers
Authors: Funt B. Lionel , Hsu Li‐Chien , Hoang P. M. 
Published: April 2003

AbstractIn the electrochemical reduction of an electroactive polymer several thousand electrons may be transferred to a single molecule. For polymers with noninteracting centers, recently developed theory indicates that the current—potential response would be identical with that of the corresponding molecule solvation, structural change, and variation in ionic environment, and may be used to probe these factors. A series of model compound of poly(vinylbenzophenone) and of poly(vinylbenzophenone‐co‐styrene) were prepared and investigated. In this study samples of various constant chain length with differing spacing of electroactive centers were employed. The current—potential measurements corresponded to the ideal theoretical case. This indicates that the behavior of the electroactive groups attached to the polymer chain was not influenced by the macromolecular environment or by neighboring group interaction.
Polymerization of allyl esters of unsaturated acids. VII. Copolymerization of methyl allyl maleate and fumarate with styrene
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractRadical copolymerizations of methyl allyl maleate (MAM) and methyl allyl fumarate (MAF) with styrene (St) are carried out in bulk using AIBN as an initiator at 60°C, and their copolymerization behaviors are compared in detail. The different rate features are observed with each other; thus in the MAF‐St copolymerization the rate was quite enhanced and, also, the maximum rate was found at the molar ratio of 1:1 in the monomer feed, whereas no maximum phenomenon of the rate was apparent for the MAM—St copolymerization. The copolymerizability of MAF with St was quite high, whereas that of MAM was very poor. The cyclization of MAM or MAF was hindered by the highly reactive St monomer. These results are discussed in terms of the formation of the charge—transfer complex between MAF and St and, furthermore, the cyclocopolymerization kinetics involving the 17 elementary reactions as the propagation reactions.
Catalysis by cationic polyelectrolytes and micelles in bisulfite oxidation
Authors: Kim O.‐K. 
Published: April 2003

AbstractThe oxidation of sodium bisulfite in the presence of cationic polyelectrolytes or micelles has been studied. The formation of cationic‐bisulfite complexes is indicated, and a kinetic analysis suggests the validity of the enzyme kinetics applied to determine the kinetic parameters. Distinct differences in the activity of cationics depend on the configuration of the cationics in solution; micelle‐forming cationics are more effective than nonmicellar polycationics, except in the case of poly(diallyldimethylammonium chloride), (PDADM). The oxidation rate is strongly affected by the presence of monomer in the system, especially where nonmicellar polycationics are involved.
NMR studies and conformations of asymmetric polyamides derived from cyclopropyl diacids and diamines
Authors: Overberger C. G. , Nishiyama T. 
Published: April 2003

AbstractThe synthesis and optical properties of the polyamides [poly(C3A˙C3B) and poly(C3A‐C3MB)] derived from asymmetric trans‐1,2‐cyclopropanedicarboxylic acids (C3A), asymmetric trans‐1,2‐diaminocyclopropanes (C3B), and asymmetric trans‐1,2‐bis(methylamino) cyclopropanes (C3MB) were reported in the preceding article. This paper describes the NMR studies and conformations of the polyamides. The NMR studies of the polyamides and their diamide models have suggested that the polyamides have about a 90° torsional angle for NH (or CH3) CH. This angle seems to be reasonable because of less steric interaction, especially for poly(+)C3A(+)C3MB. The NCH3 of the poly(+)C3A(+)C3MB in sulfuric acid‐d2 (D2SO4) is a singlet and is tentatively assigned to trans to the carbonyl oxygen of the amide group. In 2,2,2‐trifluoroethanol‐d3 (TFE‐d3) and chloroform‐d (CDCl3) it is also a singlet and is tentatively assigned to cis. The overall results obtained suggest that poly(+)C3A(+)C3MB exists in a compact helical conformation in TFE and TMS, while some conformational transition to a highly extended helical form with opposite handedness is induced by the addition of MSA. Likewise, poly(+)C3A(+)C3B must exist in some ordered conformation in the solvents studied. Possible ordered conformations of the polyamides have been proposed based on the experimental results and some assumptions.
Hydrolytically stable fluorocarbon ether bibenzoxazole polymers
Authors: Evers Robert C. , Abraham Tonson , Burkett Jerald L. 
Published: April 2003

AbstractHydrolytically and thermooxidatively stable fluorocarbon ether bibenzoxazole (FEB) polymers were synthesized by the acetic acid‐promoted polycondensation of fluorocarbon ether bis(o‐aminophenol) monomers with novel fluorocarbon ether dithioimidate ester monomers. The dithioimidate esters were derived from hexafluoropropylene oxide (HFPO) or, preferably, from a combination of HFPO and tetrafluoroethylene oxide (TFEO). The latter class of TFEO:HFPO‐derived dithioimidate esters imparted improved hydrolytic stability to the resultant FEB polymers while minimizing undesirable, concomitant increases in polymer glass transition temperatures. The polymers exhibited inherent viscosities in the range of 0.20 to 0.41 dl/g. Polymer structures were verified by elemental and infrared (IR) spectral analyses. Lower glass transition temperatures were obtained with increased fluorocarbon ether content, a minimum value of −48°C being achieved. High thermooxidative stability of the HFPO‐ and TFEO:HFPO‐based FEB polymers was substantiated by thermogravimetric analysis and isothermal aging studies in air. After isothermal aging in air for 200 hr at 288 and 260°C, representative polymers exhibited weight losses of 17 and 7%, respectively. Hydrolytic stability of the polymers was evaluated by exposure to a 95% relative humidity, 93°C environment for prolonged periods of time. Based on comparative glass transition temperature, inherent viscosity, and IR spectral data, the HFPO‐ and TFEO:HFPO‐based FEB polymers exhibited vastly improved hydrolytic stability over analogous TFEO‐based FEB polymers. Optimum hydrolytic stability and low‐temperature viscoelastic properties were achieved by the use of a TFEO:HFPO‐derived dithioimidate ester that did not contain structural isomers that would lead to sites of hydrolytic instability in the polymer backbone.
Solid‐state polymerization of long‐chain vinyl compounds. VI. In‐source polymerization of octadecyl acrylate by γ‐ray irradiation
Authors: Shibasaki Yoshio , Fukuda Kiyoshige 
Published: April 2003

AbstractThe in‐source polymerization of octadecyl acrylate in the lamellar crystal (hexagonal packing) by γ‐ray irradiation has been investigated, as compared with the two‐step and one‐step postpolymerizations. The viscosity‐average molecular weight is very high even in the initial stage and is practically saturated after 3–5 hr, although the conversion increases successively with time. The molecular weight distribution of poly(octadecyl acrylate) obtained by in‐source polymerization is very wide (Mw/Mn = 13.1, at 20°C). The results of in‐source polymerization of the long‐chain vinyl compounds can be interpreted using the cone model for polymerization probability, similar to those of one‐step and two‐step postpolymerizations.
Polymerization of acrylonitrile: Kinetics of the reaction initiated by the Fe2+/BrO3− redox system
Authors: Samal R. K. , Suryanarayana G. V. , Das D. P. , Samal S. , Nayak M. C. 
Published: April 2003

AbstractThe aqueous polymerization of acrylonitrile initiated by the bromate—ferrous redox system in aqueous sulfuric acid was studied under nitrogen atmosphere. The rate of polymerization increased with increasing concentration of ferrous in the range of 0.25‐1 × 10−2M. The percentage of conversion increased with increasing concentration of the catalyst, but beyond 2.5 × 10−3M there was a decreasing trend in the rate of polymerization. The rate varied linearly with [monomer]. The initial rate of polymerization as well as the maximum conversion increased within the range of 1–2.5 × 10−3M KBrO3, but beyond 2.5 × 10−3M the rate of polymerization decreased. The initial rate and limiting conversion increased with increasing polymerization temperature in the range 30–40°C; beyond 40°C they decreased. The effect of certain neutral salts, water‐miscible solvents, complexing agents, and copper sulfate concentration on the rate of polymerization was investigated.
Telomerization kinetics by redox catalysis: A study of reactions leading to telomers with low degrees of polymerization
Authors: Boutevin Bernard , Maubert Claude , Pietrasanta Yves , Sierra Pierre 
Published: April 2003

AbstractAn adaptation of the David and Gosselain formula for redox catalyzed telomerization was made. An equation was developed for transfer reactions between oligomer radicals and metallic ions. This equation was applied to data obtained in chlorotrifluoroethylene (CTFE)—carbon tetrachloride telomerizations catalyzed by a ferric chloride—benzoin mixture. It was found that the metal ion transfer constants (CMei) were the predominant parameters influencing the distribution of products obtained. These were found constant for degrees of polymerization greater than 2.
Synthesis and polymerization of the four 1,3‐di(cyano and/or carbomethoxy)‐substituted butadienes
Authors: Ahn Kwang‐Duk , Hall H. K. 
Published: April 2003

AbstractThe four 1,3‐di(cyano and/or carbomethoxy)‐substituted butadienes were synthesized. Their cyclopentadiene adduct precursors and, in one case, an anthracene adduct precursor were synthesized and pyrolyzed at 400–600°C (0.1–1.0 mm) to yield the four new dienes. Two crystalline precursors gave crystalline dienes 1,3‐dicyano‐1,3‐butadiene, mp 79°C, and 1‐carbomethoxy‐3‐cyanobutadiene, mp 45–46°C, in modest yields in small‐scale experiments, which were completely characterized by elemental analyses and spectra. The other two liquid precursors produced no isolable or detectable dienes but led directly to polymer. The two crystalline dienes were exceptionally reactive, polymerizing on storage or when deliberately initiated with AIBN, but were moderately stable in solution. All polymers possessed the trans‐1,4‐structure exclusively. Because of the favorable location of the electronegative substituents for stabilizing the growing radical, these new dienes are the most reactive di‐electronegatively substituted butadienes described.
Radiation‐induced cationic polymerization of β‐pinene
Authors: Adur Ashok M. , Williams Ffrancon 
Published: April 2003

AbstractThe radiation‐induced polymerization of β‐pinene carried out in bulk at ca. 25°C has been studied for different methods of monomer drying. It has been confirmed that the polymerization is sensitive to adventitious moisture and that substantial polymer yields (ca. 10% conversion per Mrad) can only be obtained under extremely dry conditions. Complete inhibition of the reaction by added tripropylamine corroborates the view that the polymerization is cationic. About half of the polymer formed is insoluble in the monomer. The number‐average molecular weights for the soluble poly(β‐pinene) fraction have been measured by vapor pressure osmometry and are in the narrow range from 1700 to 2400 with little or no dependence on the degree of monomer conversion to polymer, at least up to 80%. The results are compared with literature reports on the polymerization of β‐pinene by catalytic initiators.
Cationic oligomerization and polymerization of some propenylbenzene derivatives
Authors: Alexander R. , Jefferson A. , Lester P. D. 
Published: April 2003

AbstractA comparative study was undertaken of the cationic oligomerization/polymerization of the natural propenylbenzene derivatives, anethole, isoeugenol, and isosafrole, together with synthetic o‐methoxypropenylbenzene and N,N‐dimethyl‐p‐propenylaniline using boron trifluoride diethyletherate as catalyst. Two (optimum) reaction temperatures were employed, −12 and −45°C, and only the (E) isomers of the monomers were studied. The order of reactivity of the monomers was found to be anethole > isoeugenol > isosafrole > o‐methoxypronylbenzene as measured by following the rate of loss of monomer by proton magnetic resonance spectrometry at −12°C. N,N‐dimethyl‐p‐propenylaniline only appeared to form a complex with the catalyst. Low‐molecularweight polymeric materials were prepared from anethole, isosafrole, and isoeugenol at −45°C using the same catalyst while o‐methoxypropenylbenzene formed oligomers. Isosafrole was recovered unchanged when treated with the boron trifluoride diethyl etherate initiator system at −78°C in an attempt to increase the molecular weight of the polyisosafrole.
Aqueous polymerization of methyl methacrylate catalyzed by copper metal and some of its compounds
Authors: Moustafa A. B. , El‐Ghaffar M. A. Abd , Badran A. S. , Rabie A. M. 
Published: April 2003

AbstractThe aqueous polymerization of methyl methacrylate (MMA) with sodium bisulfite as initiator was carried out in a nitrogen atmosphere with and without inorganic substances like copper metal, cupric and cuprous oxides, and cupric sulfide. It was also done in the presence of organocopper compounds like copper phthalocyanine and copper biphthalocyanine. The catalytic effect of these compounds was studied. Mildly heated cupric sulfide proved to have a small catalytic effect on the polymerization process that may be attributed to the retarding effect of the released elementary sulfur. The catalytic effect of the different copper compounds and the copper metal equivalent contained in them was studied. The polymerization process revealed that cuprous and cupric oxides possess the highest catalytic influence. An attempt was made to investigate the role of the different anions on the polymerization process. It was found that an increase on the concentration of the copper compounds leads to a corresponding increase in the catalytic effect. It was also observed that the behavior of insoluble copper catalysts is different from that of the soluble. The effect of these catalysts on the average molecular weight of the poly(methyl methacrylate) (PMMA) produced was also examined.
Synthesis and polymerization of p‐(p′‐vinylbenzoyl)‐peroxybenzoic acid tert‐butylester: A monomer containing a photodissociable radical source
Authors: Gupta Satyendra N. , Thijs Lambertus , Neckers Douglas C. 
Published: April 2003

AbstractIn a previous report we have shown that efficiently photodecomposable, but thermally stable, peresters can be made from a compound that contains both a triplet photosensitizer functionality and a perester group. This fundamental approach has been extended to make a novel vinyl monomer containing a triplet sensitizer and a perester group. Thus, the monomer p‐vinylbenzoyl‐p‐tert‐butyl perbenzoate (VBPE) has been synthesized and polymerized by normal procedures without loss of perester activity. The resulting polymer perester can be used as an efficient photolabile radical source by irradiating at the λmax of the benzophenone carbonyl moiety. The homopolymer (PVBPE) and copolymers with other monomers, such as styrene, could be photocrosslinked with high efficiency. Copolymers of VBPE and styrene containing low percentages of VBPE have been used to initiate graft chains of poly(methyl methacrylate) by irradiating a solution of the copolymer in methyl methacrylate at 366 nm.
Thermoxidative degradation of poly(vinyl alcohol) under dynamic thermogravimetric conditions. II. Influence of the hydrolysis degree
Authors: Vasile Cornelia , Călugăru Elena Maria , Bodonea Silvia Florica 
Published: April 2003

AbstractThe influence of the degree of hydrolysis on thermoxidative degradation of the poly(vinyl alcohol) was studied. The thermoxidative degradation was carried out under dynamic thermal conditions. Taking into account the dependence of the activation energy values on the heating rate, molecular weight, degree of conversion, and degree of hydrolysis, some conclusions were drawn about the decomposition mechanism and the variation of the thermal stability.
Hydrogen evolution from water by use of viologen polymers as electron transfer catalyst
Authors: Ageishi Kentaro , Endo Takeshi , Okawara Makoto 
Published: April 2003

AbstractThe behavior of viologen polymer (P‐V2+) as an electron transfer catalyst in the reaction of hydrogen generation was studied. In the photoirradiation system, which contains triethanolamine (TEA), Ru(bpy)3+3, and P‐V2+, the amount of hydrogen evolution was less than methyl viologen (MV2+); P‐V2+, however, was more effective in sodium dithionite as the electron donor and showed higher initial rates than MV2+.
Radical polymerization in the presence of complexing agents. III. Effect of low concentrations of ZnCl2 on the radical polymerization of methyl methacrylate
Authors: Madruga E. L. , Román J. San 
Published: April 2003

AbstractThe formation of complexes between ZnCl2 and methyl methacrylate (MMA) or between ZnCl2 and AIBN was tested at two different polymerization temperatures, taking into account the Haeringer and Riess treatment. For any concentration of ZnCl2 between 0.01 and 0.1 mole/liter the formation of ZnCl2−MMA complexes is favored, whereas AIBN−ZnCl2 complexes are hardly showed. The effect of zinc chloride on the stereostructure of poly(methyl methacrylate) was also investigated at both temperatures.
A study of structure formation processes occurring with the gelation of polysulfonamide solution in dimethylacetamide
Authors: Kochervinsky V. V. , Zagainov V. M. , Sokolov V. G. , Zelenev Yu. V. 
Published: April 2003

AbstractThis work investigates spontaneous gelatination of polysulfonamide in the solution of dimethylacetamide by nuclear magnetic relaxation, small‐angle light scattering, and refractive index measurement. Two stages of the gelatination process were found to occur. Spherulites are formed in the first stage while the mobility of the solvent molecules decreases sharply. The second stage is characterized mainly by perfection of the inside structure of spherulites without a change in their size. The degree of decreasing mobility of the solvent molecules is much less in this stage than in the first stage.
Agitation effect on the rate of soapless emulsion polymerization of methyl methacrylate in water
Authors: Arai Kunio , Arai Masahiko , Iwasaki Shigeo , Saito Shozaburo 
Published: April 2003

AbstractIn order to identify the factors causing an agitation effect on the rate of soapless emulsion polymerization, the polymerization of methyl methacrylate was carried out in water. Experimental results indicated the significance of monomer transfer from monomer droplets to water. A kinetic model was proposed which would take into account this monomer transfer. This model enabled the effect of monomer transfer on the rate of soapless emulsion polymerization to be evaluated for the present system and the experimental results to be interpreted qualitatively.