bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of molecular interaction on polymerization, 9. Copolymerization of 2‐naphthyl methacrylate with acrylonitrile
Authors: Boudevska Hrissanta , Sinigersky Vesselin 
Published: April 2003

AbstractThe copolymerization of 2‐naphthyl methacrylate (2‐NM) with acrylonitrile (AN) initiated by 2,2′‐azoisobutyronitrile (AIBN) was carried out in solvents with different dielectric constants. The relative reactivity ratios of the monomers determined by the Fineman‐Ross method in the solvents used are as follows:

in chloroform: r2‐NM = 0,96 ± 0,05; rAN = 0,00 ± 0,02
in benzene: r2‐NM = 0,84 ± 0,09; rAN = 0,01 ± 0,04
in acetone: r2‐NM = 0,52 ± 0,09; rAN = 0,00 ± 0,02
in acetonitrile: r2‐NM = 0,51 ± 0,06; rAN = 0,00 ± 0,03
The capability of the monomers to form donor‐acceptor associates was shown by means of 1H NMR spectroscopy. The observed interactions between the monomer molecules on one side and between the molecules of the monomers and the solvent on the other side were used to explain the changes in the reactivity ratios of both monomers obtained in different solvents.
Solution behaviour of polyacrylamides in 0,12 M NaCl
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya 
Published: April 2003

AbstractSeven unfractionated samples of polyacrylamide have been investigated in 0,12 M NaCl by viscosity, osmotic pressure, and light scattering techniques. Viscosity‐molecular weight and 〈,s2〉w‐M̄w relationships have been established and the unperturbed dimensions were estimated from the Stockmayer‐Fixman relationship.
The spontaneous polymerization of methyl methacrylate, 7. External heavy atom effect on the initiation
Authors: Lingnau Jürgen , Meyerhoff Günther 
Published: April 2003

AbstractA dimeric biradical •M plays a central role in the initiation of the spontancous polymerization of methyl methacrylate (M1). Besides the initiation step by chain transfer reaction, a change of the multiplicity of ˙M seems to be of importance. Evidence is given by heavy atoms in the solvent or in an inert gas atmosphere, leading to an acceleration of the overall polymerization rate. The observed effect is related to the atomic number of the respective heavy atom. Measurements of the temperature dependence of the effect for carbon tetrachloride show that — as expected — no activation energy is needed for this reaction step. The results are summarized in a reaction scheme for the initiation mechanism of the spontaneous polymerization of methyl methacrylate.
Polymer‐linked acycloguanosine
Authors: Rosemeyer Helmut , Seela Frank 
Published: April 2003

AbstractPolymer‐linked 9‐(2‐hydroxyethoxymethyl)guanine (1) (acycloguanosine, acyclovir®) was prepared. Condensation of 1 with succinic anhydride gave in 77% yield 2‐(9‐guanylmethoxy)‐ethyl hydrogen succinate (2), which was coupled through its carboxylic group either to poly(L‐lysine) (M̄r = 55000) or to N‐(6‐aminohexyl)carbamoylmethylated dextran T80 to yield the polymers 3 and 4 (ligand concentrations in 3: 30 – 48 μmol of 2/g, in 4: 100 – 171 μmol of 2/g). From both polymers the antiviral 1 could be released by controlled saponification; the rate of drug delivery was found to be a function of pH and temperature. The polymeric carrier system 3 was degraded by endo‐dextranase, and the carrier system 4 by trypsin, yielding low‐molecular‐weight derivatives of the pharmacon.
A peculiar temperature‐dependent behavior of iodine species at the formation of chromophore between iodine and aqueous poly(vinyl alcohol)
Authors: Yokota Toshio , Kimura Yoshiharu 
Published: April 2003

AbstractThe blue colored complex between poly(vinyl alcohol) (PVA) and iodine was prepared at 5°C by mixing an aqueous solution of PVA with an aqueous ethanolic solution of iodine containing boric acid. The absorption spectrum of the system shows bands at 226 nm (A), 290 nm (B), 355 nm (C), and 650 nm (D). Their relative absorbances change largely depending on temperature. When the system is gradually warmed, the chromophoric band D decays and the intensity of band A increases. By lowering the temperature again to 5°C the concentration of chromophore increases. It was found that the decay and the re‐formation of the chromophore are reversible in the temperature range 5 to 15°C. Above 15°C, contrarily, hysteresis effects are encountered for the re‐formation. Thus, when the chromophore is re‐formed at 5°C, the spectra shows an isosbestic point at 420 nm, between bands C and D. The dependence on temperature of bands B and C is quite independent from each other, which strongly indicates that the latter band should be assigned to another iodide species than the I−3 ion (band B) and the I− ion (band A). Based on these experimental data a new mechanism is proposed involving the complex ion I−3 · I2 which is supposed to be a precursor of the chromophoric pentaiodide ion I5−.
Macroion‐counterions interactions in dilute aqueous solution of iota‐ and kappa‐carrageenan segments
Authors: Rizzo Roberto , Paradossi Gaio , Crescenzi Vittorio 
Published: April 2003

AbstractInteractions of counterions with segmented kappa‐ and iota‐carrageenan sulfated polysaccharides were investigated by means of microcalorimetric and potentiometric measurements in dilute aqueous solution. The condensation of counterions onto the charged polymer chains leads, in general, to conformational transitions of the disorder‐to‐order type. A difference in the ability of different pairs of ionic species (monovalent/divalent counterions) to induce conformational transitions of carrageenate salts is demonstrated.
Structure of poly[(ethylene glycol)‐(diethylene glycol) terephthalate] as determined by chemical degradation
Authors: Fakirov Stoyko , Seganov Ilija , Prangowa Lilijana 
Published: April 2003

AbstractThe influence of preliminary thermal treatment and diethylene glycol (DEG) content on the rate of degradation, DEG amount in the degradation products, WAXS, relative viscosity, and density of the understructed poly(ethylene terephthalate) (PET) is studied upon aminolysis with hydrazine hydrate at 60 and 85°C. The results indicate that (i) the aminolysis is a two‐stage process, corresponding to the degradation of the amorphous and crystalline regions and (ii) the phase boundary is not sharp. A model is proposed, describing the comonomer distribution in the semicrystalline copolyesters. The comonomer units are concentrated mainly in the amorphous regions. The effect of degradation conditions like temperature, concentration, duration, particle size, deposition of low molecular products on the polymer surface, etc. is also discussed.
Crystal and molecular structure of a new spiro phosphorane monomer, 7‐oxo‐5‐phenyl‐5λ5‐phospha‐1,4,6‐trioxaspiro[4.4]nonane
Authors: Higuchi Taiichi , Fukuyo Makoto , Saegusa Takeo , Kobayashi Shiro 
Published: April 2003

Abstract7‐oxo‐5‐phenyl‐5λ‐5‐phospha‐1,4,6‐trioxaspiro[4.4]nonane (3a) (C11H13O4P, monoclinic, P21/n, a = 14,751(2), b = 5,577(1), c = 14,490(3) Å, β = 106,91(2)°, V = 1140,5 Å3, Dx(Z = 4) = 1,398 g · cm−3, MW = 240,20, mp = 80°C) forms hygroscopic white needle‐like crystals. The structure was solved by direct methods and the final R value is 0,068. The geometry around the phosphorus is trigonal bipyramidal with two five‐membered rings in the apical‐equatorial planes. The three P‐O bond lengths are 1,615(5) (equatorial), 1,670(4) and, 1,808(4) Å (apical).
Modification au deuxième degré de polymères époxydés, 2. Addition de l'acide benzoïque sur polyènes époxydés
Authors: Soutif Jean‐Claude , Brosse Jean‐Claude 
Published: April 2003

AbstractThe addition of benzoic acid to the oxirane ring of epoxidized polymers of dienes is limited by side reactions which are promoted by increase of time, temperature, or epoxide concentration. Only high [Acid]/[Epoxide] ratios afford good yields of modification of the epoxidized polymers.
Biologically active polycations, 4. Synthesis and antimicrobial activity of poly(trialkylvinylbenzylammonium chloride)s
Authors: Ikeda Tomiki , Tazuke Shigeo , Suzuki Yasuzo 
Published: April 2003

AbstractVarious poly(trialkyl‐3‐(and 4‐)vinylbenzylammonium chloride)s were prepared and their antibacterial activities were assessed by the conventional spread plate method and the viable counting method. They are in general more active against Gram‐positive bacteria such as Bacillus subtilis and Staphylococcus aureus than against Gram‐negative bacteria such as Escherichia coli, Aerobacter aerogenes and Pseudomonas aeruginosa. Compounds with the longest alkyl chain studied (dodecyl) were found to exhibit particularly high activity, and this was ascribed to the contribution of the increased hydrophobicity of the compounds to the activity. The most significant finding was that the polymers was discussed and interpreted in terms of their greater contribution to each elementary process in the cidal action: their favored adsorption onto the bacterial cell surface and the cytoplasmic membrane with subsequent disruption of its integrity.
The molecular structures of (RS)‐1,2‐diphenylethyl methacrylate and (RS)‐α‐tert‐butylbenzyl methacrylate
Authors: Kageyama Hiroyuki , Miki Kunio , Kasai Nobutami , Okamoto Yoshio , Yashima Eiji , Hatada Koichi , Yuki Heimei 
Published: April 2003

AbstractThe molecular structures of (RS)‐1,2‐diphenylethyl methacrylate (DPEMA) and (RS)‐α‐tert‐butylbenzyl methacrylate (t‐BBMA) were determined by means of X‐ray diffraction. Crystals of (RS)‐DPEMA are monoclinic, space group C2/c, a = 33,341(3), b = 5,916(1), c = 15,911(2) Å, β = 106,42(1)°, and Z = 8. Crystals of (RS)‐t‐BBMA are also monoclinic, space group P21/c, a = 6,028(1), b = 31,009(3), c = 15,207(1) Å, β = 96,780(8)°, and Z = 8. Both structures were solved by the direct method and refined by the block‐diagonal least‐squares procedure: DPEMA, R = 0,113 for 1 100 observed reflections and t‐BBMA, R = 0,081 for 2206 non‐zero reflections, respectively. The molecule of DPEMA has an antiperiplanar conformation as to the CC and CO double bonds about the C(1)C(2) bond, a synperiplanar conformation as to the CO and CO bond about the C(1)O(1) bond, and an anticlinal conformation about the O(1)C(5) bond. One of the two t‐BBMA molecules in an asymmetric unit has an antiperiplanar conformation as to the CC and CO double bonds about the C(1)C(2) bond, whereas the other antiperiplanar molecule may contain some synperiplanar conformation. Both molecules have a synperiplanar conformation as to the CO and CO bonds about the C(1)O(1) bond and an anticlinal conformation about the O(1)C(5).
Solution behaviour of hydrolysed polyacrylamides in 0,12 M NaCl
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya 
Published: April 2003

AbstractSix unfractionated samples of polyacrylamide were hydrolysed to varying extents. The partially hydrolysed polyacrylamides were investigated by viscosity, osmatic pressure and light scattering techniques in 0,12 M NaCl. The molecular weights of the hydrolysed polyacrylamides confirmed the absence of main chain degradation during hydrolysis. Intrinsic viscosities and dimensions increased with increasing extent of hydrolysis. On correlating the intrinisic viscosities with the extent of hydrolysis, a linear relationship between intrinsic viscosities and the square root of the extent of hydrolysis was obtained.
Expansion coefficients of hydrolysed polyacrylamides from light scattering measurements
Authors: Kulkarni Rajendra A. , Gundiah Subbaraya 
Published: April 2003

AbstractThe dimensions of partially hydrolysed polyacrylamides with varying molecular weights and extents of hydrolysis determined by light scattering were used to verify the relative applicability of the various macroion expansion theories. Expansions attributable solely to the presence of electrostatic charges were evaluated with references to the dimensions of the polyacrylamides used for hydrolysis. Total expansions and expansions due to long‐range interactions were evaluated with reference to the estimated unperturbed dimensions of the strating polyacrylamides and the hydrolysed polyacrylamide samples, respectively. The expansion coefficients obtained from light scattering measurements were higher than those evaluated from intrinsic viscosities. The differences were maximum (30 – 100%) for the total expansion coefficients. Considering the variation of the Flory viscosity constant Φ with molecular weight and charge density, these differences were ascribed to the uncertainty in the applicability of the light scattering method for the determination of the dimensions of polyelectrolytes. However, the variation of the expansion coefficients with the extent of hydrolysis and molecular weight were similar to those of the expansion coefficients obtained from viscosity measurements. The total expansion coefficient was qualitatively in confirmity with the theory of Chien and Ishihara with reference to its dependence on charge density.
Quantitative structural analysis of graft copolymers by light scattering measurements in mixed solvents
Authors: Kuhn Rainker 
Published: April 2003

AbstractTheoretical calculations have shown that it should be possible to determine the molar mass of the grafted chains of graft copolymers by light scattering measurements in suitable mixed solvents, and moreover, that this should be possible without the backbone having to be degraded, without the ungrafted backbone having to be isolated, and without the refractive index increment having to be determined after dialysis. Among the conditions that have to be met are the requirements that the mixed solvent must be isorefractive with respect to the backbone and that the preferential solvation of the grafted chains must be independent of their molar mass. The method is applied to fractions of graft copolymers with styrene or styreneacrylonitrile (SAN) being grafted onto ethylene/vinyl acetate copolymers, from which ungrafted polystyrene or SAN copolymer has been removed by solvent demixing. With this method the molar mass and the number of grafted chains, the coupling of backbone molecules via grafted chains, the shrinking and segregation of the individual grafted chains and the incompatibility of the grafted chains with the backbone polymer can be determined.
Morphology, crystallization, and thermal behaviour of isotactic polypropylene/low density polyethylene blends
Authors: Martuscelli Ezio , Pracella Mariano , Volpe Gaetano Della , Greco Pietro 
Published: April 2003

AbstractThe morphology, the crystallization and thermal behaviour of isotactic polypropylene (IPP) in its blends with two different samples of low density polyethylene (LDPE) was investigated at temperatures high enough to prevent any solidification of LDPE. It is found that pre‐existing liquid LDPE domains are incorporated in intra‐spherulitic regions during the isothermal crystallization of iPP. The radial growth rate of spherulites is almost unaffected by the LDPE content. The overall rate of crystallization of iPP, on the contrary, is strongly depressed by the addtion of LDPE. A depression of the equilibrium melting temperature of iPP, due to kinetic and morphological effects, is also observed. The depression of the overal kinetic rate constant is accounted for by the negative effect (decrease in the number of nuclei) that the addition of LDPE has on the primary nucleation process of iPP.
Dynamic viscoelasticity of polyacetylene during oxidation
Authors: Chen Show‐An , Li Liang‐Shun 
Published: April 2003

AbstractDynamic viscoelasticity measurements at 90°C suggest an oxidation process for pristine polyacetylenes (PA's). For cis‐rich PA, the oxidation can be divided into three regions: surface oxidation, bulk oxidation, and crosslinking. Crosslinking also occurs at the end of the surface oxidation period but does not occur in the bulk reaction period. For trans‐rich PA, oxygen doping was complete after the first 15 min and occurred to a smaller extent than that of the cis‐rich PA. The rate of reaction of trans PA chains with oxygen is slow in comparision to that of crosslinking by radical combination or addition reactions with the PA chains. In the case of trans PA the concentration of radical chains formed by reaction with oxygen retains a steady value after the initial period up to the end of oxidation.
Hydroperoxydation primaire de terpolymères d'éthylène/propylène/éthylidene‐5 norbornène‐2
Authors: Coiffier Francis , Arnaud René , Lemaire Jacques 
Published: April 2003

AbstractEthylene/propylene/5‐ethylidene‐2‐norbornene terpolymers (1) are very sensitive to photooxidation. In the early stages, hydroperoxidation occurs specifically at the carbon atom in α‐position to the ethylidene group. Isolated and hydrogen‐bonded hydroperoxides can be detected by IR spectrophotometry at 3550 and 3380 cm−1, respectively. In post‐thermolysis experiments at temperatures above 60°C the associated hydroperoxides were found to be less stable than the isolated hydroperoxides. Saturation of the ethylidene groups is concomitant with the decomposition of associated hydroperoxides, which are transformed thermally and photochemically into alcohols and cyclic saturated ketones. The lack of vinyl groups shows that hydroperoxidation proceeds only at the norbornene cycle.
Caractérisation texturale par thermoporométrie, à l'état gonflé par l'eau, de résines échangeuses d'anions
Authors: Quinson Jean‐François , Brun Maurice , Spitz Roger , Bartholin Michel 
Published: April 2003

AbstractThermoporometry is used to determine the size and the volume of the cavities of anion exchange resins swollen in water. The conditions of the application of thermoporometry are different of those met with non‐functionalised resins. An important fraction of the water remains bond to the polymer and does not change its state when cooling. Nevertheless, it is possible to deduce from the freezing of the non‐bound water the geometrical characteristics of the cavities of the resin which determine the fluid inside circulation. In most cases it is possible to confirm the pore size distribution by nitrogen adsorption and mercury porosimetry on resins partly swollen with water.
The influence of the valence state of titanium in MgCl2‐supported titanium catalysts on olefin polymerization
Authors: Kashiwa Norio , Yoshitake Junichi 
Published: April 2003

AbstractThe relationships between the valence state of titanium in MgCl2‐supported titanium catalysts and polymerization performances for ethylene and propylene were studied. When the titanium species of the supported titanium catalyst 1 was preliminarily reduced by treating it with AlEt3, the resulting catalyst system 2 had lost the activity for propylene polymerization completely. The catalyst activity for ethylene polymerization was found to be reduced to 20% of that of the original catalyst 1. In the AlEt3‐pretreated catalyst 2 no Ti4+ is found and 80% of the total titanium is present as Ti2+. The catalyst system 2 plus AlEt3, however, does exhibit activity towards ethylene‐propylene copolymerization, propylene insertion being possible if the end of the growing polymer chain is an ethylene unit. The titanium in the AlEt3‐reduced catalyst 2 could be oxidized again by treatment with various agents. The oxidized catalysts 3, in conjunction with freshly added AlEt3 as cocatalyst, are active for propylene polymerization and show increased activity for ethylene polymerization in relation to the extent of oxidation.
Polymerization of methyl methacrylate initiated by manganese(III) acetate
Authors: Reddy A. Venkatarami , Rao A. Kameswara 
Published: April 2003

AbstractThe kinetics of thermal polymerization of methyl methacrylate (MMA) initiated by manganese(III) in sulfuric acid is studied in the temperature range between 40 and 607deg;C. The rate of monomer consumption is found to be dependent on [MMA]2, [H+]−1 but independent of [Mn3+]. The rate of manganic ion consumption is directly proportional to [MMA], [Mn3+] and inversely proportional to [H+]. The chain length is directly proportional to [MMA] and inversely proportional to [Mn3+] and [H+]. A plausible reaction mechanism with initiation by Mn3+ OH− species and termination by the interaction of Mn3+ with the polymer radical is proposed.
Microdomain structure of poly(styrene‐4‐vinylpyridine) diblock copolymers
Authors: Ishizu Koji , Inagaki Katsumi , Bessho Keiichi , Fukutomi Takashi 
Published: April 2003

AbstractA series of AB and BAB type poly(styrene‐4‐vinylpyridine) diblock copolymers with a sharp distribution of molecular weights were synthesized to study relationships between the molecular weight and domain size of lamellar and spherical microdomains. The domain sizes of diblock copolymer specimens cast from chloroform or 1,1,2‐trichloroethane were estimated from transmission electron micrographs. As a result, the lameller domain spacings, predicted from Halfand's theory, agree well with the experimental results. The radius of spherical domains is far below the theoretical values predicted from Helfand's theory, though.
The interaction of comonomers in the solution copolymerization of N, N‐dimethyl‐2‐aminoethyl methacrylate with methacrylic acid
Authors: Lokaj Jan , Doskočilová Danica , Hrabák František 
Published: April 2003

AbstractThe copolymerization parameters of N,N‐dimethyl‐2‐aminoethyl methacrylate (DAMA) with methacrylic acid (MAA) were determined at 50°C in benzene, dimethylformamide, and pyridine solutions. The Alfrey‐Price constants e and Q of the two monomers were determined by copolymerization of DAMA and MAA with styrene in the same solvents. Using these constants, the copolymerization diagrams of the pair DAMA‐MAA were calculated and compared with the experimentally determined ones. The mutual interaction between the comonomers is discussed.
Mikrokalorimetrische untersuchungen der enthalpischen wechselwirkungen von polymethylmethacrylaten verschiedener taktizität in lösung
Authors: Killmann Erwin , Graun Karl 
Published: April 2003

AbstractEnthalpies of dilution, dissolution, and complex formation of atactic and tactic poly(methyl methacrylate)s (PMMA) were measured at 30°C with a heat flux microcalorimeter of TianCalvet. The enthalpies of dilution in 4‐methyl‐2‐pentanone, toluene, and carbon tetrachloride are positive (endothermic). Because of different mutual interactions between the solvent molecules and the polymer segments they are dependent on the polarity of the solvent, on the concentration, the molar mass and the tacticity of PMMA, and on the temperature and time of annealing. The solution enthalpies are negative due to the enthalpy of the amorphous state of the polymer. They are also influenced by the parameters just mentioned and by the pretreatment of the PMMA probes. The exothermic stereocomplex formation between the iso‐and syndiotactic triads can be determind quantitatively by the enthalpies of mixing of iso‐ and syndiotactic PMMA‐samples. The enthalpy of complex formation is related to the mass of the isotactic triads and increases with growing excess of the syndiotactic triads in the sense of a completion of the complex formation of the isotactic triads.