bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autooxidation and stabilization of undoped and doped polyacetylenes
Authors: Yang Xun‐Zhuan , Chien James C. W. 
Published: April 2003

AbstractAutooxidations of polyacetylene have been measured by volumetric, infrared, and isothermal TGA weight uptake techniques. The rate of oxygen uptake is 9 × 10−7 mol (g s)−1 at 70°C and the overall activation energy is about 10 kcal mol−1. The maximum oxygen uptake corresponds to [CHO0.25]x. Above 100°C there is oxidative degradation of the polymer completely to volatile products. The rate constant for the oxidative degradations at 160°C is ca. 1.5 × 10−5s. Autooxidation does not result in formation of significant amounts of crosslinking because there are not carbonaceous residues. TGA under a stream of oxygen showed the degradation to be complete at ca. 420°C leaving no residues. Autooxidation is much slower if the polymer is compressed to higher bulk density. Radical scavengers such as BHT and 4010 are effective stabilizers. Hydroperoxide decomposers, such as DSTDP, does not help in the stabilization; spin trap BPN accelerates the oxidation of polyacetylene. Iodine and AsF5 doped polyacetylenes are oxidatively much more stable than undoped polymers. Perchlorate doped polyacetylenes begin to lose weight as soon as heated above room temperature. Even in an inert atmosphere the polymers often undergo explosive decomposition.
A morphological analogue of japanese lacquer. Grafting of p‐hydroxystyrene onto pullulan by ammonium persulfate initiation in dimethylsulfoxide
Authors: Chen Yen‐Yuan , Oshima Ryuichi , Kumanotani Ju 
Published: April 2003

AbstractPullulan‐g‐poly(p‐acetoxystyrene) (I) was prepared using ammonium persulfate (APS) as an initiator in dimethylsulfoxide (DMSO) solution. I was deacetylated by hydrazine hydrate to yield pullulan‐g‐poly(p‐hydroxystyrene) (II). The degree of polymerization of the grafted poly(p‐hydroxystyrene) chain (III) was 15–20. Despite the effective grafting (%), this method caused the degradation of pullulan. The number of branch polymer chains per pullulan molecule were evaluated to be 0.9 to 2.5 from number average molecular weights of the permethylated II and III. The glass transition temperature of II was higher than that of III, indicating that the polar hydroxyl groups of pullulan in the graft polymer caused an increase in the rigidity of the grafted polymer chains. Pullulan‐g‐poly(o‐hydroxystyrene) and pullulan‐g‐poly(MMA) were also readily prepared by this method.
Radiolysis of resist polymers. VI. Copolymers of trihalophenylmethacrylate and methyl methacrylate
Authors: Lu P. H. , Babu G. N. , Chien J. C. W. 
Published: April 2003

AbstractCopolymers of several compositions of methyl methacrylate (MMA), trichlorophenyl methacrylate (TCPMA), and tribromophenyl methacrylate (TBPMA) have been synthesized and characterized. Gamma radiolysis yields are very sensitive to the presence of the halogenated monomers. With less than 10% of the halogenated monomer in the copolymers. Gs values were found to be much greater than that of PMMA. However, the halogenated monomer introduces a tendency toward crosslinking. The results are consistent with the enhancement of chain scission by dissociative electron capture and the tendency of phenyl radical intermediates to cause crosslinking. These structure‐property relationships were found to be valid for all the homopolymers and copolymers investigated in this series.
Block polymer preparation via both anionic and free radical polymerization
Authors: Tung L. H. , Lo G. Y. S. , Griggs J. A. 
Published: April 2003

AbstractA new method of block polymer preparation using combined anionic and free radical polymerization was investigated. In the method the first monomer was polymerized anionically. The resulting polymeric anions were then reacted with an episulfide to form a polymer with mercaptan end‐groups. This mercapto—polymer was mixed with a second monomer(s) in an inert solvent for the free radical polymerization. Conventional free radical initiation methods were used to initiate the polymerization of the second monomer but because of the high chain transfer constant of the mercaptan groups, a large number of the free radical chains would grow from the first polymer to form a block polymer. Block polymers difficult or impossible to make by direct anionic polymerization can thus be prepared. Several block polymers, including the new thermoplastic elastomers, poly[(styrene‐co‐acrylonitrile)‐b‐butadiene‐b‐(styrene‐co‐acrylonitrile)] and poly(bromostyrene‐b‐butadiene‐b‐bromostyrene) were prepared by this method.
Graft copolymerization onto rubber. V. Graft copolymerization of methyl methacrylate onto rubber using potassium peroxydiphosphate as initiator
Authors: Lenka Subasini , Nayak Padma L. , Das Anil P. , Mishra Surendra N. 
Published: April 2003

AbstractThe graft copolymerization of methyl methacrylate onto natural rubber (NR) is investigated using potassium peroxydiphosphate as the initiator. The rate of grafting is determined by varying monomer concentration, peroxydiphosphate concentration, and temperature. The graft yield increased with an increase in monomer concentration up to 1.4082M/L and thereafter the graft yield decreases. The graft yield increases significantly with an increase of peroxydiphosphate concentration up to 150 X 10‐1M/L and thereafter the graft yield decreases. The grafting reaction is temperature dependent. A suitable kinetic scheme is proposed and the rate equation is evaluated.
The elucidation of the 1H‐ and 13C‐NMR spectra of bis[N,N‐di(2,3‐epoxypropyl)‐4‐aminophenyl]methane (TGMDA) and composite with bis(4‐animophenyl)sulfone (DDS) using two‐dimensional fourier transform techniques
Authors: Herring F. G. , Jagannathan N. R. , Luoma G. 
Published: April 2003

AbstractThe application of Fourier transform (FT) two‐dimensional nuclear magnetic resonance spectroscopy to the study of the composite of bis[N,N‐di(2,3‐epoxypropyl)‐4‐aminophenyl] methane (TGMDA) and the curing agent bis(4‐aminophenyl)sulfone (DDS) is discussed. The combination of 2D‐J resolved and homonuclear (proton) shift correlated experiments permits the complex proton spectrum due to the glycidylamine moiety to be completely elucidated. The potential utility of this in the study of the aging of prepreg is briefly discussed.
Sequential analysis of polyesters by stepwise chemical degradation: Preparation of degradation products
Authors: Rossbach Volker , Windeln Johannes , Schmitz Franz P. 
Published: April 2003

AbstractModel reactions for the sequential analysis of polyesters, especially those of the poly(ethylene terephthalate) and poly(butylene terephthalate) type, by stepwise chemical degradation were performed. The cyclic degradation products, containing the reagent and an ethylene terephthalate or butylene terephthalate unit, terephthalic acid mono(2‐{o{N‐<N′‐[4‐(iminomethyl‐) benzoyl‐]> 2′‐(imino)ethoxycarbonyl‐}iminobenzoyl‐} oxyalkyl) ester N″‐lactams, were deliberately synthesized.
Thermal and radical polymerization of anthracene acrylates and methacrylates
Authors: Simionescu Cristofor I. , Grigoras Mircea , Bărboiu Virgil 
Published: April 2003

AbstractThe thermal and radical‐induced polymerizations of 9‐anthrylmethyl acrylate (I), 9‐anthrylmethyl methacrylate (II), 1′‐(9‐anthryl)ethyl acrylate (III), and 1′‐(9‐anthryl)ethyl methacrylate (IV) have been studied. It was found that the radical‐induced polymerization takes place for the methacrylates only, while thermal polymerization leads to polymers for both types of monomers and takes place by Diels–Alder cycloaddition in the case of acrylates, and by both normal enchainment and Diels–Alder cycloaddition in the case of methacrylates.
Regiospecifically substituted poly(phenylacetylenes) as potential chemical detectors
Authors: Wentworth Stanley E. , Bergquist Paul R. 
Published: April 2003

AbstractThe synthesis of a series of regiospecifically substituted polyphenylacetylenes via sealed tube thermal polymerization has been accomplished. Measurement of their conductivities alone and in the presence of SO2, NH3, H2O, or dimethyl methylphosphonate vapors shows them to be extremely weakly conductive, contrary to previous reports. Higher conduction in these prior materials is thus attributed to the presence of ionic impurities arising from their method of synthesis. These results cast doubt on the suitability of such materials alone as chemical sensors but suggest that intentional incorporation of ionic species might be effective.
Study of the microstructure of tetrahydrofuran‐3,3 dimethyloxetane copolymers by 13C‐NMR spectroscopy.
Authors: Guzmàn J. , Riande E. , Rico M. , Santoro J. 
Published: April 2003

AbstractThe microstructure of tetrahydrofuran (A)‐3,3 dimethyloxetane (B) copolymers was studied by 13C‐{1H}‐NMR spectroscopy. Only the methyl carbons corresponding to the 3,3 dimethyloxetane unit appear as a singlet, whereas the other carbons present a more complicated spectral pattern than it would be expected if ϵ effects were negligible. The assignment of the resonance signals allowed the determination of the values of the probabilities of the different triads, which were in good agreement with those obtained from the reactivity ratios.
Organic solid photochromism by photoreduction mechanism: Polar aprotic viologen copolymers
Authors: Kamogawa Hiroyoshi , Amemiya Suguru 
Published: April 2003

AbstractCopolymers of vinyl viologens such as N‐vinylbenzyl‐N′‐yalkyl and N‐(γ‐methyacryloyloxy)propyl‐N′‐propyl‐4,4′‐bipyridinium dihalides and polar aprotic comonomers such as N‐vinyl‐2‐pyrrolidone (VP) and N,N‐dimethylacrylamide (DMA) were prepared by the copolymerizations of vinyl viologens with DMA and the chemical modifications of VP copolymers containing reactive halogens. Copolymers containing various viologen anions such as Br−, BF, SO, and I− were also prepared by the anion exchange of copolymers containing Cl−. The photocolor developments of these aprotic copolymers in the film state were completely reversible and faster than for the corresponding copolymers with protic comonomers such as acrylamide and 2‐hydroxyethyl acrylate, all with characteristic absorption spectra attributable to single radical cations.
Photopolymerization initiated by carbonyl compounds. VII. Solvent effects on biacetyl photoinitiation
Authors: Encinas M. V. , Garrido J. , Lissi E. A. 
Published: April 2003

AbstractBiacetyl is solvated by methanol or water giving an α‐substituted alkanone. Irradiation of the solvated species at 300 nm in the presence of vinyl acetate or vinyl pyrrolidone, produces a significant amount of polymer. The photoprocesses leading to active free radicals are considered to be a type I photocleavage of the α‐substituted alkanone.
Characterization of surface endgroups in polystrene latexes
Authors: Jayasuriya R. M. , El‐Aasser M. S. , Vanderhoff J. W. , Yue H. J. 
Published: April 2003

AbstractThe stability against electrolytes for all‐sulfate, all‐carboxyl, and all‐hydroxyl, polystyrene model latexes followed the order, sulfate > carboxyl > hydroxyl when determined from an IR light scattering technique. Two types of hydroxyl endgroups were identified by 13C‐NMR (chemical shift correlations, and model compound comparisons), for the polystyrene model latexes. One type was due to termination of growing chain with an oligomer with a single monomer unit, and the other due to termination of growing chains. The surface hydroxyl groups of an all‐hydroxyl latex were derivatized with hexafluoroacetone, and quantified using 19F‐NMR techniques. Good agreement with the indirect conductometric titration values were obtained.
Polymerization of styrene miniemulsions
Authors: Choi Y. T. , El‐Aasser M. S. , Sudol E. D. , Vanderhoff J. W. 
Published: April 2003

AbstractPolymerization of styrene miniemulsions, prepared using a mixed emulsifier system comprising sodium lauryl sulfate and cetyl alcohol, was carried out using both water‐soluble (potassium persulfate) and oil‐soluble [2,2′‐azobis‐(2‐methyl butyronitrile)] initiators. The effects of variation of initiator concentration, polymerization temperature, and added inhibitor on the kinetics and particle‐size distributions were investigated to obtain more quantitative evidence concerning the locus of polymerization in miniemulsion systems. Experimental results for the kinetics and particle‐size distributions clearly showed that monomer droplets became the main source of polymer particle formation. This was attributed to the fact that stable emulsions with droplet diameters in the range of 0.05 to 0.15 μm were produced using this mixed‐emulsifier system. In this size range, droplet initiation could effectively compete with other mechanisms due to their large surface area. Their size was indeed similar to the corresponding latex particle size obtained after polymerization.
Radical copolymerization of γ‐methylene‐Δα,β‐butenolide derivative: Ethyl(E)‐5‐oxo‐2,5‐dihydrofuran‐2‐ylidene‐acetate
Authors: Nagai Katsutoshi , Akiyama Kazuhiko , Kuramoto Noriyuki 
Published: April 2003

AbstractRadical polymerications including co‐ and terpolymerizations of a γ‐methylene‐Δα,β‐butenolide derivative, ethyl (E)‐5‐oxo‐2,5‐dihydrofuran‐2‐ylideneacetate(EODY) was investigated. The monomer had no homopolymerizability but copolymerized with styrene (ST) and 1,3‐cyclohexadiene to yield alternating copolymers. From IR and 1H‐NMR spectra of the copolymers, the 1,4‐addition was confirmed to exclusively occur for the conjugated double bond of EODY. Terpolymerization for the system involving an acceptor monomer such as maleic anhydride, α‐chloromaleic anhydride, or 7,7,8,8‐tetracyanoquinodimethane in addition to ST and EODY gave the terpolymer containing about 50 mol% of ST, in spite of a high fraction of ST in the feed. It was inferred that such an apparent behavior of EODY as an acceptor monomer could be due to a resonance‐stabilization of the propagating radical having EODY as a terminal unit, which is also responsible for the poor yields of the copolymers and terpolymers.
Soluble magnesium and titanium catalyst components for ethylene polymerization
Authors: Yano Takefumi , Ikai Shigeru , Washio Katsutoshi 
Published: April 2003

AbstractThe catalyst system comprised of a heptane solution of magnesiumoctoate‐H2O‐Tetrabutoxytitanium/diethylaluminumchloride was highly active for ethylene polymerization at a high temperature. High productivity for the catalyst system at a low temperature was achieved by the aging of the catalyst components. The effect of different orders of addition of the catalyst components on productivity was investigated to assume the role of each components in the formation of active species.
In‐situ poling and synthesis of NLO chromophore‐bearing polyurethanes for second harmonic generation
Authors: Kitipichai P. , La Peruta R. , Korenowski G. M. , Wnek G. E. 
Published: April 2003

AbstractThe preparation of six diol and one triol monomers bearing donor–acceptor chromophores is described. The monomers contain the N,N′‐bis(2‐hydroxyethyl)aniline unit with various acceptor groups attached in some cases via azo or olefin linkages, at the para position. Acceptors studied include nitro, tricyanovinyl, cyclobutene‐1,2‐dione, and imidazolidine‐2,4‐dione. Poled polymer films were prepared by thermal polymerization of these with 2,4‐toluenediisocyanate (TDI) in the presence of an electric field generated by a corona tip. The resulting thin (ca. 1 μm), glassy polymer films were shown to exhibit reasonably good second harmonic generation efficiencies. Preliminary results show that the polymers with higher Tg's have the best temporal stability. The polymer derived from the diol bearing an imidazolidine‐2,4‐dione acceptor shows only a ca. 30% decrease in its second harmonic generation (SHG) signal over 200 days at room temperature, even though it is not crosslinked. We attribute this to hydrogen bonding interactions from the urethane and imidazolidine‐2,4‐dione groups. A crosslinked film derived from the triol and TDI has an exceedingly stable SHG response at room temperature, and no decrease in the SHG response is observed at 100°C for a few hours. © 1993 John Wiley & Sons, Inc.
Synthesis of polymers bearing pendant norbornadiene moieties by addition reaction of poly(glycidyl methacrylate‐co‐methyl methacrylate)s with 2,5‐norbornadiene‐2‐carboxylic acids
Authors: Nishikubo Tadatomi , Kawashima Tatsuo , Watanabe Sadayuki 
Published: April 2003

AbstractPolymers bearing photoresponsive norbornadiene (NBD) moieties were synthesized by the addition reaction of poly(glycidyl methacrylate‐co‐methyl methacrylate)s containing pendant epoxide groups with 3‐phenyl‐2,5‐norbornadiene‐2‐carboxylic acid (PNBC), 3‐[(phenyl)carbamoyl]‐2,5‐norbornadiene‐2‐carboxylic acid 3‐[(4‐acetylphenyl) carbamoyl]‐2,5‐norbornadiene‐2‐carboxylic acid (APCND), and 3‐[(4‐methoxyphenyl)carbamoyl]‐2,5‐norbornadiene‐2‐carboxylic acid using tetrabutylammonium bromide as a catalyst in DMF. The polymers bearing pendant PNBC or APCND moieties have higher photochemical reactivity in the film state than the polymers bearing pendant PCND or MPCND moieties. Although the pendant quadricyclane (QC) group produced by the photoirradiation of the PNBC moiety in these polymers has excellent storage stability in the film state, without catalyst at room temperature, the QC group in the polymer film with the catalyst reverts gradually to the NBD moiety at room temperature. © 1993 John Wiley & Sons, Inc.
Hexene‐1 polymerization by homogeneous zirconocene and heterogeneous‐supported TiCl3 catalysts
Authors: Chien James C. W. , Gong Ben Min 
Published: April 2003

AbstractMgCl2‐supported TiCl3 catalysts, with and/or without electron donor modifier (internal Bi or external Be), were compared with rac‐ethylenebis(indenyl)zirconium dichloride (1) activated with either MAO or the cation forming agent, triphenyl carbenium tetrakis(pentafluorophenyl)borate (2), with triethylalumium (TEA). The activities of the heterogeneous catalysts depend on the presence or absence of the Lewis base, were relatively insensitive to the temperature of polymerization, and produce poly(hexene) with molecular weights up to 106. The 1/MAO catalyst has about five times higher activity at 50°C but is almost inactive at −30°C; the overall activation energy is 12.4 kcal mol−1. In contrast, the activity for hexene polymerization by the 1/2/TEA catalyst is actually slightly greater at lower temperature. The MW's of poly(hexene) obtained with the zirconocenium catalysts are only in the tens of thousands because of rapid β‐hydride elimination by the electrophilic cationic Zr center. © 1993 John Wiley & Sons, Inc.
One‐pot synthesis of nylon 6–clay hybrid
Authors: Kojima Yoshitsugu , Usuki Arimitsu , Kawasumi Masaya , Okada Akane , Kurauchi Toshio , Kamigaito Osami 
Published: April 2003

AbstractNylon 6–clay hybrid is a molecular composite of nylon 6 and uniformly dispersed silicate layers of montmorillonite. One‐pot synthesis of the hybrid was carried out by the following procedures. Montmorillonite was dispersed in water, and then ε‐caprolactam, acid (phosphoric acid, hydrochloric acid, benzenesulfonic acid, isophthalic acid, trichloroacetic acid, or acetic acid), and 6‐aminocaproic acid were added to the dispersion. The mixtures were reacted at 260°C for 6 h, yielding the nylon 6–clay hybrids (1potNCHs). X‐ray diffraction revealed that the silicate layers of 1potNCH by phosphoric acid were uniformly dispersed in the nylon 6 matrix. The 1potNCH had excellent mechanical properties. The strength and the modulus of the hybrid increased compared with previously reported nylon 6–clay hybrid (NCH) synthesized by montmorillonite intercalated with 12‐aminolauric acid. The heat distortion temperature (HDT) of the 1potNCH was 160°C, which was 8°C higher than that of NCH. In other 1potNCHs, montmorillonite had a smaller effect on the increase of those properties, and interlayer spacing of montmorillonite was observed at ca. 20 Å. © 1993 John Wiley & Sons, Inc.
Propenyl ethers. III. Study of the photoinitiated cationic polymerization of propenyl ether monomers
Authors: Crivello J. V. , Jo K. D. 
Published: April 2003

AbstractThe effects of photoinitiator structure and variations in the experimental parameters on the rate and extent of the photoinitiated cationic polymerization of propenyl ether monomers were studied. It was found that the photoinitiators can be divided into two classes: those which exhibit an induction period and those which do not. It was demonstrated that in those propenyl ether polymerizations using iodonium salts and certain sulfonium salts which do not have an induction period, a free radical chain‐induced decomposition of the onium salt takes place. The reactivity of a particular onium salt photoinitiator was shown to be related to its reduction potential. It was also shown that the structure of the monomer plays a major role in the free radical induced decomposition reaction. © 1993 John Wiley & Sons, Inc.
Stereospecific polymerization of butene‐1 with supported titanium catalyst
Authors: Diao Jianbo , Wu Qing , Lin Shangan 
Published: April 2003

AbstractButene‐1 was polymerized with a highly‐active supported titanium catalyst which was developed in this laboratory. The influences of various conditions (e.g., catalyst composition, temperature, external ester, H2, triethylaluminum, and catalyst concentration) on the catalytic activity, decay of polymerization rate, molecular weight, and isotacticity of the products were studied in detail. The structural properties of the PB‐1 were characterized by WAXD, DSC, and 13C‐NMR. It was found that the catalyst TiCl4, Ti(OBu)4/MgCl2/ethyl benzoate (EB)/Ph2SiCl2–AlEt3 shows high activity, i.e., 3.2 × 104 g PB/g Ti h. Isotacticity of the product was increased by adding p‐CH3C6H4COOEt into the catalytic system. Molecular weight of the product can be easily controlled by H2. The decay of polymerization rate with time fulfills the equation: Rt − Rs = (Ro − Rs)e−βt. © 1993 John Wiley & Sons, Inc.