bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of hindered amine light stabilizers on the photooxidative stability of high‐density polyethylene
Authors: Bigger Stephen W. , Delatycki Oskar 
Published: April 2003

AbstractThe photoprotective effectiveness of various polymeric and nonpolymeric hindered amine light stabilizers (HALS) was determined by exposing samples of high‐density polyethylene (HDPE) containing these additives to ultraviolet (UV) light and measuring the resultant oxygen uptake characteristics. Values of the initial quantum yield for oxygen uptake calculated for these formulations indicate that the higher molecular weight HALS compounds are less effective photostabilizers than the nonpolymeric HALS, and this is partly attributable to their decreased mobility in the polymer matrix. It was further found that the addition of an ultraviolet absorber (UVA) to a formulation containing a polymeric HALS compound enhances its photostability, although this phenomenon may be partly due to synergism between the UVA and the antioxidant, the latter having been added as part of the base stabilization. The antagonism which exists between certain sulfur‐containing antioxidants and HALS compounds was also investigated and it was found that the lower molecular weight sulfur‐containing antioxidants exhibit the greatest degree of antagonism. The results confirm that the mobility in the polymer matrix of the stabilizer system can serve as an explanation of its effectiveness. The article provides evidence that the technique of oxygen uptake monitoring is a sensitive and rapid method of assessment of polymer photostability in the presence of stabilizer systems.
The influence of the ligands on the catalytic activity of a series of RhI complexes in reactions with phenylacetylene: Synthesis of stereoregular poly(phenyl) acetylene
Authors: Furlani A. , Napoletano C. , Russo M. V. , Camus A. , Marsich N. 
Published: April 2003

AbstractThe catalytic activity of a series of [Rh L‐L chel]X complexes, in which we have varied the unsaturated ligand [L‐L = cis, cis‐cycloocta 1,5‐diene(cod) or 2,5‐norbornadiene(nbd) the nitrogen chelating ligand [chel = 2,2′‐bipyridine(bipy), 2,2′‐dipyridylamine(dipyam), 2,2′‐bipyrazine (bipz), 4,4′‐dimethyl‐2,2′‐bipyridine (4,4′‐Me2bipy)] and the counter ion [X = PF6, ClO4, BPh4], has been examined in reactions with phyenylacetylene (PA). The catalytic behaviour of the [Rh(cod)Cl2],tmeda (tmeda = N,N,N′,N′tetramethylethylendiamine), [Rh(cod)Cl2],teda] (teda = triethylendiamine), of the dimer [Rh(cod)Cl]2, and the use of NaOH as cocatalyst in different reaction conditions was also examined. The influence of the ligands on the catalytic activity of these RhI complexes is discussed. 1H and 13C NMR spectra have shown that highly stereoregular polyphenylacetilene can be obtained. Conditions for homogeneous doping of PPA, to obtain materials whose conductivity varies over 10–11 magnitude orders, are proposed. The stability of the doped polymers is also discussed.
Stereoselective hydrolysis of amino acid esters by dipeptide catalysts and byN‐decanoyl‐histidine in surfactant aggregate domains
Authors: Ihara Yasuji , Nakanishi Eiji , Akiyama Akemi , Yamamoto Hiroko , Nango Mamoru , Koga Joichi 
Published: April 2003

AbstractThe rate constants of hydrolysis of the enantiomers of amino acid nitrophenyl esters by catalytic domains composed of cationic surfactant aggregates and dipeptide catalysts orNdecanoyl‐L‐histidine have been determined at pH 7.30. The dipeptide catalysts shows large rate enhancement and stereoselectivity in aggregate domains. The surfactant structural effects are examined by investigation of the rate constants and stereoselectivities, and the nature of stereoselective catalysis is discussed.
Synthesis of optically active polynucleotide analogs with polytrimethylenimine backbones and thymine moieties
Authors: Overberger C. G. , Chang Ji Young , Gunn V. E. 
Published: April 2003

AbstractPolynucleotide analogs with polytrimethylenimine backbones and optically active 2‐(thymin‐1‐yl)propionic acids as pendants were prepared. Linear polytrimethylenimines were obtained by ring‐opening polymerization of 2‐phenyl‐5,6‐dyhydro‐4H‐1,3‐oxazine and subsequent hydrolysis of the resulting polymers. 2‐(Thymin‐1‐yl)propionic acids were reacted with N‐hydroxy succinimide to form active esters. Optical purities of active esters were determined by NMR with chiral chemical shift reagents. The polynucloetide analogs and related monomer and dimer model compounds were prepared by grafting reactions using active esters.
Seeded polymerization of vinyl acetate using monodisperse poly(vinyl acetate) latex particles
Authors: Hayashi Sadao , Komatsu Akihiko , Hirai Toshihiro 
Published: April 2003

AbstractThe seeded polymerizations of vinyl acetate, using monodisperse poly(vinyl acetate) latex particles prepared in the absence of emulsifiers with potassium persulfate, have been investigated at 70°C with potassium persulfate as an initiator. New small particles were formed in the system containing a small amount of seed particles, but were not observed in the system containing a large amount of seed particles. The size of the secondary particles increased, and their number decreased, with an increase in the seed particle number. The minimum diameter of PVAc particles, which are stabilized by the sulfate ion groups bound at the end of polymer chains during polymerization, was determined to be 0.12 μm diameter from the limiting total surface area of seed particles which prevented further secondary nucleation. The minimum diameter of the particles increased as the speed of the stirrer increased. The new small particle number calculated using this value agreed well with that formed in the seeded polymerization.
Poly(enamine‐ketones) from hydrogen‐terminated aromatic dipropynones and aromatic diamines
Authors: Bass R. G. , Sinsky M. S. , Connell J. W. , Waldbauer R. O. , Hergenrother P. M. 
Published: April 2003

AbstractPoly(enamine‐ketones) were prepared by the nucleophilic (Michael‐type) addition of various aromatic diamines to 1,1′‐(1,3‐ or 1,4‐phenylene)bis(2‐propyn‐1‐one)(1,3 or 1,4‐PPO) in m‐cresol at 5–23°C. The low molecular weight polymers (inherent viscosity of 0.25 dL/g) exhibited limited solubility in organic solvents. Glass transition temperatures were generally undetectable by differential scanning calorimetry while polymer decomposition temperatures (10% weight loss), as measured by thermogravimetric analysis, were observed from 355 to 419°C. Polymers prepared from 1,4‐PPO were semi‐crystalline as shown by wide‐angle X‐ray diffraction. The poly(enamine‐ketone) structure was confirmed by matching infrared spectral characteristics of the polymers with those of well‐characterized model enamine ketones.
Effect of ureas on the viscometric behavior of water‐soluble isotactic poly(2‐hydroxyethyl methacrylate)
Authors: Jeon Sang Il , Jhon Mu Shik 
Published: April 2003

AbstractIsotactic poly(2‐hydroxyethyl methacrylate) (PHEMA) is soluble and has the compact random coil structure in water solution. The effect of six ureas (thiourea, urea, methylurea, ethylurea, 1,3‐dimethylurea, and tetramethylurea) on the viscometric behavior of aqueous solutions of isotactic PHEMA as a function of urea concentrations at 25°C has been investigated. The compact random coil structure is found to disappear as ureas are added. The result is discussed in terms of water structure breaking and making effect of solutes, and hydrophobic interactions. In addition, experiments were performed with aqueous isotactic PHEMA solutions at four different temperatures. Isotactic PHEMA in pure water has the most compact conformation at 20°C.
Synthesis of polymer materials by low energy electron beam. VIII. Formation mechanism of microporous urethane‐acrylamide film
Authors: Ando Masayuki , Goto Takakazu , Tsuchiya Mitsuru , Uryu Toshiyuki 
Published: April 2003

AbstractThe formation mechanism of microporous film which was obtained by casting a methyl ethyl ketone (MEK)/N,N‐dimethlformamide (DMF) solution of an electron beam (EB)‐reactive urethane‐acrylamide prepolymer was discussed. The porosity and crystallinity increased with increasing DMF content in the solvent mixture. This correlation was explained by a progressive slight coagulation and nucleation of the prepolymer due to the difference in volatility between MEK and DMF. As the result, when the DMF content reached 25 vol%, micropores were formed throughout the film. Such a mechanism was supported by the localization of the acrylamide groups at the surface which was induced by the crystallization and by the interaction of amide groups with DMF. The polymerization of acrylamide groups by EB could fix the microporous morphology.
Synthesis and photo‐induced dissolution of polymers bearing imino sulfonate groups
Authors: Shirai Masamitsu , Tsunooka Masahiro , Tanaka Makoto , Nishijima Kanji , Ishikawa Katsukiyo 
Published: April 2003

AbstractNovel photosensitive polymers were synthesized by the copolymerization of methyl methacrylate and 1,2,3,4‐tetrahydro‐1‐naphthylideneimino p‐styrenesulfonate (NISS) and by the ternary polymerization of methyl methacrylate, methacrylic acid, and 9‐fluorenylideneiminop‐styrene‐sulfonate (FISS). NISS and FISS units showed good sensitivity to light of wavelengths below 300 nm and below 366 nm, respectively. Although the polymers were insoluble in aqueous alkaline solutions, on irradiation with UV light they became soluble in aqueous alkaline solutions. A remarkable decrease in molecular weight of the polymers was observed during the photolysis of imino sulfonate groups incorporated into the polymers, which assisted the dissolution of the irradiated polymers.
The synthesis, characterization, and polymerization of 1‐ethyl‐4‐[(2‐methacryloxy)ethyl carbamoyloxymethyl]‐2,6,7‐trioxabicyclo[2.2.2]octane
Authors: Herweh J. E. 
Published: April 2003

AbstractThe synthesis of a monomer bearing polymerizable acrylic and bicyclic ortho ester groups is described. The monomer 1‐ethyl‐4‐[(2‐methacryloxy)ethyl carbamoyloxymethyl]‐2,6,7‐trioxabicyclo[2.2.2]octane is characterized by elemental analysis, 1H‐ and 13C‐NMR spectra, mass spectra, and heat of polymerization. The free‐radical and ionic polymerization of 4 is probed as is its copolymerization with several vinyl monomers.
Determination of the reactivity parameters for the copolymerization of butyl acrylate with vinyl acetate
Authors: Bataille P. , Bourassa H. 
Published: April 2003

AbstractThe composition of vinyl acetate–butyl acrylate copolymers obtained with batch emulsion polymerization have been studied by 1H‐NMR. Using the integrated copolymerization Meyer–Lowry equation, the apparent reactivity ratios of the two monomers were calculated as 10.67 for r1, the reactivity ratio of butyl acrylate (BA), and 0.024 for r2, the reactivity ratio of vinyl acetate (VAC). These results were compared with those obtained by other methods.
Synthesis and characterization of certain new poly(bisimide)s. I
Authors: Nanjan M. J. , Sivaraj K. 
Published: April 2003

AbstractMaleic and citraconic anhydrides were reacted with several diamines to obtain a novel class of high temperature resistant bisimides.1–3 The bisimides were characterized by melting points, elemental analysis, UV–Vis, 1H‐ and 13C‐NMR, and mass spectral analysis. The bisimide monomers were then polymerized by the addition process. A poly(amidemaleimide) was also synthesized by reacting maleic anhydride with p‐aminobenzhydrazide. The thermal stability of these highly crosslinked poly(bisimide)s were examined by TGA and DTA. A neat bisimide monomer obtained from 2,2′‐bis[4(p‐aminophenoxy)phenyl] propane with maleic anhydride namely, 2,2′‐bis[4‐(p‐maleimidophenoxy)phenyl]propane was reacted with 2,2′‐bis[4(p‐aminophenoxy)phenyl]propane by the Michael reaction.4 A fiber glass cloth reinforced laminate was prepared from bismaleimide and amine mixture and the mechanical properties of the test laminate evaluated.
Catalyzed degradation of poly(vinylchloride). III. Zinc(II) chloride catalysis
Authors: Owen Eryl D. , Msayib Kadhum J. 
Published: April 2003

AbstractWhen PVC films containing zinc(II) chloride were heated in the temperature range 65–95°C, broad absorptions developed in the 250–900 nm region with maxima around 610 nm. The development of the color, the rate of which was proportional to the ZnCl2 content, was preceded by an induction period, the length of which depended on the temperature. The activation energy of the process decreased as the ZnCl2 content of the film increased. Color developments in air and in vacuum were compared.
A comparative account of properties of novel unsaturated polyesters synthesized by different polyesterification processes
Authors: Agrawal J. P. , Chouk M. P. , Satpute R. S. , Bhale V. C. 
Published: April 2003

AbstractNUP‐7(II) has already proved its potential for inhibition of CMDB propellants. NUP‐7(I), NUP‐7(II), and NUP‐7(III) have been synthesized by “one‐step,” “two‐step,” and “three‐step” processes of polyesterification and their various characteristics have been studied and discussed in terms of theoretical considerations. NUP‐7(III) possesses better elongation and higher chemical resistance (low nitroglycerine absorption)—two contradictory characteristics reported in the case of most of the polymeric materials. It therefore will have added advantages over NUP‐7(II) for military as well as civil applications.
Copolyamides of nylon‐4,6 and nylon‐4,T
Authors: Gaymans R. J. , Aalto S. , Maurer F. H. J. 
Published: April 2003

AbstractCopolyamides of nylon‐4,6 and nylon‐4,T were prepared by a two‐step method: (1) a prepolymerization in an autoclave (40 min at 210°C) and (2) a postcondensation in the solid state (4 h, 260°C). On these materials was studied the melting behavior with DSC, the crystalline structure with WAXS, the water absorption, and the mechanical properties with a torsion pendulum. In these copolyamides the order was found to remain high, but the crystalline structures of ‐4,6 and ‐4,T were not isomorphous. The torsion moduli increased with ‐4,T content both at RT and at 140°C.
Conducting polymers. I. Electrical conductivity of poly(bis‐p‐phenylenediaminosulphoxide)
Authors: Ghander A. M. , El‐Sonbati A. Z. , Diab M. A. 
Published: April 2003

AbstractPoly(bis‐p‐phenylenediaminosulphoxide) was prepared by Michael addition of p‐bis‐N‐sulphinylphenylenediamine with p‐phenylenediamine at 150°C. Thermal and electrical behaviors of the polymer have been studied. The polymer is found to have increased conductivity possibly due to the participation of lone pairs of electrons on nitrogen and sulphur atoms with σ bond of the macrochain. Thermogravimetric analysis indicates that the polymer is fairly stable than other conducting polymers up to 200°C. The activation energy of the polymer was measured and found to be 13 kcal mol−1.
Synthesis and characterization of liquid crystalline polyacrylates and polymethacrylates containing benzyl ether and diphenyl ethane based mesogens
Authors: Hsu Chain S. , Percec Virgil 
Published: April 2003

AbstractThe synthesis and radical polymerization of a novel series of acrylates and methacrylates containing p‐cyanophenyl‐p‐hydroxybenzyl ether, p‐methoxyphenyl‐p‐hydroxybenzyl ether, and 1‐(p‐cyanophenyl)‐2‐(p‐hydroxyphenyl) ethane groups attached to the polymerizable group through aliphatic spacers containing 11 and 6 methylenic units is described. The resulting polymers were characterized by differential scanning calorimetry and optical polarization microscopy. All polymers exhibited enantiotropic mesomorphism. Low molar mass compounds based on benzyl ether or diphenyl ethane units exhibit only monotropic or virtual transitions. This demonstrates that the “polymer effect” stabilizes mesophases obtained from “mesogenic units” which do not contain rigid interconnecting groups.
Chemical release control: Carbamates of 3‐vinylphenyl and 2‐methacryloyloxyethyl isocyanates and perfume and herbicide alcohols
Authors: Kamogawa Hiroyoshi , Kohno Hiroyuki , Kitagawa Rikiya 
Published: April 2003

AbstractPolymerizable carbamates were synthesized from 3‐vinylphenyl and 2‐methacryloyloxyethyl isocyanates and perfume and herbicide alcohols, such as 2‐phenethyl alcohol, citronellol, geraniol, 1‐menthol, borneol, and 2‐(2,4‐dichlorophenoxy)‐ and 2‐(2,4,5‐trichlorophenoxy)ethyl alcohols. Copolymerization of these carbamate monomers and N‐vinyl‐2‐pyrrolidone with AIBN in dioxane gave respective copolymers. Hydrolyses of both monomers and copolymers, however, required severe acid conditions, although different chemical structures gave different hydrolytic behaviors.
Coordination structure and magnetic property of poly(pyridilenemethylidenenitriloiron)s
Authors: Nishide Hiroyuki , Yoshioka Naoki , Tsuchida Eishun , Inoue Hidenari 
Published: April 2003

AbstractPoly[bis(2,6‐pyridinediylmethylidenenitrilohexamethylenenitrilomethylidene)iron sulfate] was said to be a ferromagnetic compound by earlier investigators. This polymer and its derivatives are carefully reprepared and their unusual magnetic property is reinvestigated spectroscopically. The counter anion species and spacer length of the polymers affect their coordination structure and magnetism. Mössbauer spectroscopy and x‐ray diffractometry on the polymers indicate that their unusual magnetic property is caused by the ferromagnetic iron oxide slightly formed in the polymers.
Direct polyamidation with phosphorus oxychloride in pyridine
Authors: Higashi Fukuji , Kobayashi Akira 
Published: April 2003

AbstractDirect polycondensation of aromatic dicarboxylic acids and diamines with phosphorus oxychloride (POC) was successfully carried out to give polyamides of high inherent viscosity, when POC was reacted selectively and completely with a two molar quantity of carboxyl groups. To achieve the selective and complete reaction, factors, such as the amount of POC used, reactions of POC with the dicarboxylic acids by adding of POC to the acids or its reverse addition under various conditions, and aging after addition were fully examined. The reaction was proposed to proceed via a bifunctional cyclic phosphoric–carboxylic anhydride through stepwise reaction of POC with carboxyl groups.
Study of the synthesis of poly(isobutylene‐b‐amide‐11) by polycondensation α,ω‐dianhydride oligoisobutylene with α,ω‐diamino oligoamide‐11. II. Synthesis of the block copolymers by reaction in solution
Authors: Tessier Martine , Marechal Ernest 
Published: April 2003

AbstractSeveral di‐, tri‐ or multiblock poly(isobutylene‐b‐amide‐11)s are prepared by reaction of α‐mono or α,ω‐dianhydride oligoisobutylenes with α‐mono or α,ω‐diamino oligoamides, in o‐dichorobenzene at 140°C. They are characterized mainly by 1H‐ and 13C‐NMR spectroscopy and GPC, using the trifluoroacetylation technique. Their thermal differential chromatograms are reported and analyzed.
Binding of butyl orange by poly(2‐dimethylaminoethyl methacrylate) and copolymers of 2‐dimethylaminoethyl methacrylate and N‐vinyl‐2‐pyrrolidone: Peculiar temperature dependence of the binding
Authors: Kozuka Hiroshi , Hosokawa Toshitsugu , Takagishi Toru 
Published: April 2003

AbstractThe temperature dependence of the binding of butyl orange by a homopolymer of 2‐dimethylaminoethyl methacrylate (DMAEMA) and copolymers of DMAEMA and N‐vinyl‐2‐pyrrolidone (VPy) has been examined at various pH's. The binding is very much dependent upon the temperature of the system, the pH of the binding medium, and the DMAEMA content in the polymer. In this case maximal binding is obtained at approximately 15–25° in the temperature range measured, although in most cases which have been examined, the degree of binding increases steadily with increasing temperature. This peculiar temperature dependence of the binding becomes more pronounced as the pH and the DMAEMA content are increased. The appearance of the peculiarity is discussed in terms of the pH‐induced conformational changes of the polymer and the hydrophobicity of the polymer.
Adenine and thymine grafts on polyethyleneimine
Authors: Smith Walter T. , Kluttz William F. , Palmieri Donna , Butterfield D. Allan 
Published: April 2003

AbstractGraft polymers of three different molecular weights of polyethyleneimine (PEI) with 9‐(vinylsulfonylethyl) (9‐VSE)‐adenine and 1‐(vinylsulfonylethyl) (1‐VSE)‐thymine were prepared. PEI's having molecular weights of 600, 1200, and 1800 were used and various ratios of VSE‐nucleobases to ethyleneimine were employed in the grafting process. As expected, a decrease in the nucleobase substitution in the resulting graft polymer resulted in an increase in its water solubility. The degree of substitution in the graft polymers was calculated from sulfur determinations: in most cases this degree of substitution indicated that not all of the VSE derivative has reacted with the PEI due to the highly branched nature of the latter. The presence of nucleobase stacking in the polymers was studied by UV spectroscopy. Stacking was observed for the adenine polymers in both DMSO and 0.1N HCl while stacking in the thymine polymers was observed in 0.1N HCl but not in DMSO. The absence of stackingwithin the thymine polymers in DMSO was attributed to complexation of primary amino groups of the PEI backbone with the pyrimidine ring.
Co‐oligomerization of ethylene and higher linear alpha olefins. II. Olefin reactivities in various reaction steps of co‐oligomerization with nickel ylide‐based system
Authors: Kissin Y. V. 
Published: April 2003

AbstractPart I described co‐oligomerization reactions of ethylene and various linear α‐olefins (propylene, 1‐butene, 1‐hexene, 1‐heptene, 1‐octene, and 1‐decene) in the presence of the homogeneous catalyst consisting of sulfonated nickel ylide and diethylaluminum ethoxide. The present article analyzes olefin reactivities in various reaction steps of the co‐oligomerization reactions as well as reactivities of various catalytic species. Chain propagation reactions (insertion into the NiC bonds) with participation of α‐olefins exhibit poor regioselectivity, primary insertion being ca. 60% more probable than the secondary insertion. Ethylene is significantly more reactive in chain propagation reactions: 50–70 times compared to olefin primary insertion and 100–120 times compared to olefin secondary insertion. Reactivities of α‐olefins in chain propagation reactions decrease slightly for higher olefin alkyl groups. Reactivities of NiC bonds in chain propagation and chain termination reactions strongly depend on the structure of the alkyl group attached to the nickel atom. The NiCHRCH2R bond has very low reactivity in ethylene insertion reaction and usually decomposes in the α‐hydrogen elimination process. Kinetic analysis of olefin co‐oligomerization reactions provides numerous analogies with olefin copolymerization reactions in the presence of Ziegler–Natta catalysts.
Anionic polymerization of lactones initiated by alkali graphitides. IV. Copolymerization of ε‐caprolactone initiated by KC24
Authors: Gitsov Ivan , Rashkov Iliya Bl. , Panayotov Ivan M. , Golub′ Alexandr 
Published: April 2003

AbstractThe copolymerization of ε‐caprolactone (ε‐CL) with octamethylcyclotetrasiloxane (D4) and styrene (St) under the action of the second‐stage potassium graphitide KC24 was investigated. The copolymerizations were carried out in bulk or in xylene at 20°C. The content of the block copolymer ε‐CL/D4 in the polymerization mixture was 60–95%, the molecular weight ranging between 150,000 and 300,000. The data for the copolymers' composition obtained by 1H‐NMR and GPC showed 14–20% of D4‐units in the copolymer. The amount of the block copolymer ε‐CL/St in the polymerization products was 0–87%, and the molecular weights in the case of copolymer formation were between 100,000 and 500,000. The content of St‐units in the copolymers was from 10 to 75% as shown by GPC and 1H‐NMR. The mechanism of action of the initiator is discussed.