bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition and microstructure of a copolyester formed in the melt‐mixing of poly(ethylene terephthalate) and poly(ethylene truxillate)
Authors: Montaudo Giorgio , Montaudo Maurizio S. , Scamporrino Emilio , Vitalini Daniele 
Published: April 2003

AbstractThis study shows that is possible to determine the composition and microstructure of the copolyester formed in the melt‐mixing process of poly(ethylene truxillate)System. name of truxillic acid: 2,4‐diphenylcyclobutane‐1,3‐dicarboxylic acid.
(PETx) and poly(ethylene terephthalate) (PET), by applying a novel method of statistical modeling of mass spectra of copolymers. The peak intensities of molecular ions appearing in the fast atom bombardment mass spectrum of the melt‐mixed equimolar mixture of PETx and PET were found to reflect the relative amounts of oligomers present in the sample and to be directly related to the microstructure of the copolymer formed. The statistical analysis of copolymers allows one to generate a number of different theoretical mass spectra that can be fitted with the experimental mass spectrum data, thus determining the most likely copolymer composition.
Stereospecific polymerization of methylthiirane in homogeneous phase, 4. Solvent effect on stereospecificity and enantioasymmetry
Authors: Boucard Valérie , Dumas Philippe , Sigwalt Pierre , Rucar Delphine , Guérin Philippe 
Published: April 2003

AbstractThe living stereospecific polymerization of methylthiirane initiated by a chiral cadmium compound was run in different solvents. The general features of the mechanism of stereoregulation are the same as in bulk. In heptane and in heptane/propylene carbonate mixtures, the stereospecificity of the reaction does not depend on monomer concentration and on the dielectric constant ε of the medium. This independence of stereospecificity is in agreement with the absence of a variation of the complexation constant between a model cadmium derivative and the monomer with the variation of ε in a large range. The enantioasymmetric process depends on the molecular weight of the chain bearing the active sites. A change from diastereoisomeric to enantiomeric forms of active sites occurs for molecular weights around 50000. The enantioasymmetric constant depends on the nature of the medium and we observed a Born law for the dependence of the enantioasymmetric constant versus reciprocal dielectric constant: log kR ∝ 1/ε. This effect can be explained by a variation of the reactivities of the two types of active sites and occurs without a change in their relative amounts.
Water‐soluble polymers bearing biologically active residues, 1. Synthesis and characterization of poly(ether‐ester)s bearing hydroxyl side groups and their derivatization with 1‐naphthylacetic acid
Authors: Sepulchre Maurice , Kraba Nadjat Wafia , Sepulchre Marie‐Odile , Spassky Nicolas , Manolova Nevena , Ignatova Milena , Rashkov Iliya 
Published: April 2003

AbstractThe synthesis of low‐molecular‐weight poly(ether‐ester)s bearing hydroxyl side groups by poly‐condensation, in 1‐methyl‐2‐pyrrolidone at 105–110°C, of the potassium salts of racemic malic and (R,R)‐tartaric acids and α‐(2‐bromoethyl)‐ω‐bromopoly(oxyethylene)s of different molecular weights is described. The polymers were characterized by GPC and 1H and 13C NMR. The fixation of 1‐naphthylacetic acid, a plant growth regulating agent, was successfully achieved in the case of poly(ether‐ester)s deriving from tartaric acid, by carrying out the esterification reaction at room temperature in the presence of N,N′‐dicyclohexylcarbodiimide and 4‐dimethylaminopyridine.
Synthesis and electrical and optical properties of poly‐(2‐methoxy‐1,4‐phenylenevinylene) and copolymers
Authors: Shim Hong‐Ku , Hwang Do‐Hoon , Lee Kwang‐Sup 
Published: April 2003

AbstractPoly(2‐methoxy‐1,4‐phenylenevinylene) (PMVP) and copolymers containing both unsubstituted (1,4‐phenylenevinylene, PV) and 2‐methoxy‐1,4‐phenylenevinylene (MPV) units were prepared in thin films from their water‐soluble sulfonium salt precursor polymers. Drawn films (L/L0 = 6) of the PMPV homopolymer could be doped with I2 vapor and FeCl3 to give conductivities of 3,2 and 4,0 ċ cm−1, respectively. The conductivity of FeCl3‐doped copolymer films ranged from 100 to ca. 102 ċ cm−1 depending on the composition. The third‐order nonlinear susceptibility, χ(3), for the PMPV film was investigated by degenerate four‐wave mixing technique using 400 femtosecond pulses at 602 nm. A relatively large χ(3) value (7,9 ċ 10−10 esu) with a subpicosecond response was observed.
Conducting polymers from anodic coupling of some N,N′‐bridged 2,2′‐bipyrrolyl monomers
Authors: Berlin Anna , Pagani Giorgio , Zotti Gianni , Schiavon Gilberto 
Published: April 2003

AbstractAnodic coupling in CH3CN + 0,1 M tetraethylammonium perchlorate of some 2,2′‐bipyrrolyl monomers bridged by X groups at the N,N′‐positions (X = CHCH (1), o‐C6H4 (2) CH2 (3), (CH2)2 (4) and (CH2)3 (5)) produces conducting, α‐coupled polypyrroles (from IR spectroscopy), containing 0,25–0,30 counteranions per pyrrole ring (from elemental analysis). The in‐situ conductivity spans from values commonly found for N‐substituted polypyrroles (4 ċ 10−3 S/cm for 5) to unusually high values (2,5 S/cm for 4). A linear correlation between redox potentials and log of conductivities of the polymers evidences the influence of the polymer electronic properties of charge transport.
Synthesis of membranes for the dehydration of water/acetic acid mixtures by pervaporation, 2. Poly(vinyl alcohol) membranes containing covalently bonded carboxylic groups
Authors: Nguyen Trong Q. , Essamri Azzonz , Schaetzel Pierre , Néel Jean 
Published: April 2003

AbstractPoly(vinyl alcohol) (PVA) membranes containing small amounts of fixed carboxylate groups were prepared by two methods: reaction with chloroacetic acid in alkaline medium, and polymerization of acrylic acid on radical sites issued from Ce4+ ‐oxidation of PVA membranes. In the first method, when the reaction was carried out on the dissolved PVA, the crystallinity was greatly reduced, leading to a large increase in permeation flux, a slight decrease in selectivity and a significant increase in the overall performance. The activation energy of permeation was slightly decreased after the reaction. Clear qualitative correlations between different properties were obtained. In the second method, grafting was carried out on the solid membrance and the crystallinity degree was not significantly altered, yet enough to yield membranes with slightly lower selectivity and higher permeability. The Arrhenius plots of permeation rates for some membranes in acetic acid/water mixtures of different compositions showed a transition temperature which is reminiscent of a glass transition temperature the value of which is decreased by the presence of solvent molecules.
Porous copolymers of trimethylolpropane triacrylate and acrylonitrile
Authors: Kolarz Bozena N. , Wojaczyńska Maria , Trochimczuk Andrzej W. 
Published: April 2003

AbstractThe homopolymer of trimethylolpropane triacrylate (TMPA) was synthesized by suspension polymerization using a thermodynamically good solvent (toluene) as a porogen (vol. ratio 1:1). This polymer possesses a high specific surface area (437 m2 · g−1) and porosity (50%). It was found by sorption of benzene and cyclohexane that the majority of the pores are in the range of 1–5 nm. Sorption of phenol, a standard sorbate, from a water solution is proportional to the specific surface area of the mesopores. This sorption is higher than that of nonspecific sorbents (like styrene/divinylbenzene copolymers) and smaller than the sorption of specific ones (like acrylonitrile/divinylbenzene copolymers).Two sets of reactive copolymers were obtained. In the first set, TMPA (20–40 vol.‐%) was polymerized with acrylonitrile (AN) in the presence of a constant amount of toluene as an inert diluent (vol. ratio 1:1). In the second set of copolymers the cross‐linking degree was kept constant (30 or 40 vol.‐% of TMPA) but various solvent mixtures were used, namely: toluene/tetradecane or hexadecane, toluene/2‐ethylhexanol, cyclohexanol/tetradecane or hexadecane, cyclohexanol/2‐ethylhexanol (vol. ratio 9:1). It was found that all the copolymers are macroporous (volume of pores approx. 1,0 cm3 · g−1) but those obtained in the presence of good solvents display a higher specific surface area and hence better sorption properties towards phenol than those obtained in the presence of poor solvents. The swelling of AN/TMPA copolymers is smaller than that of the TMPA homopolymer due to the presence of additional physical crosslinks formed by the strongly polar nitrile groups.
On the structure of the mesomorphic form of syndiotactic polystyrene
Authors: Petraccone Vittorio , Auriemma Finizia , Poggetto Francesco Dal , De Rosa Claudio , Guerra Gaetano , Corradini Paolo 
Published: April 2003

AbstractIn this contribution, the X‐ray diffraction (XRD) pattern of a highly oriented sample of syndiotactic polystyrene in the mesomorphic form, collected by an automatic diffractometer, is presented, thus providing quantitative and more complete information relative to the diffracted intensity. The structural changes induced by annealing procedures in mesomorphic samples are shown through the analysis of the XRD patterns: both unoriented and oriented mesomorphic samples are transformed gradually into α‐form crystals. On the basis of these evidences and of preliminary comparisons between the calculated Fourier transform of simplified models and the experimental diffraction intensity, it is suggested that the local organization in triplets of trans‐planar chains, typical of the different modifications of the α‐form, would be largely present also in the disordered chain agglomerates of the mesomorphic form.
The applicability of copolymer composition and sequence distribution data to the mechanistic study of the alternating copolymerisation of maleic anhydride with substituted styrene derivatives
Authors: Brown Paul G. , Fujimori Kiyohisa , Brown Anthony S. , Tucker David J. 
Published: April 2003

AbstractThe composition and sequence distribution of copolymers of maleic anhydride (MA) with p‐methoxystyrene (p‐MST) and p‐chlorostyrene (p‐CST) prepared in ethyl methyl ketone at 50 ± 0,1°C were analysed using 13C DEPT NMR techniques, in order to compare the applicability of composition and sequence distribution data to the study of the mechanism of copolymerisation using the terminal, penultimate and complex‐participation models. In the case of the strongly alternating copolymerisation of p‐MST with MA, the comparison of models on the basis of sequence distribution data was found to be better at separating each model in terms of its applicability, with the complex‐participation model providing the best fit to the data. In the case of the less strongly alternating copolymerisation of p‐CST with MA, neither method of comparison could clearly distinguish between the penultimate and complex‐participation models.
Electron microscopy on highly branched polystyrene starshaped polymers
Authors: Buchholz Udo , Lutz Pierre , Kunz Martin , Burchard Walther 
Published: April 2003

AbstractThe technique of transmission electron microscopy (TEM) in combination with electron spectroscopic imaging and digitized image processing was used for determination of particle size and size distribution of a starshaped polystyrene sample. The results were compared with measurements of the translational diffusion coefficient Dz from dynamic light‐scattering method. The particle diameter dEM achieved by TEM‐measurements is in good agreement with the effective hydrodynamic radius Rh from the Stokes‐Einstein relationship.
Pressure and solvent influences on the shear thinning behavior of moderately concentrated solutions of poly(butyl methacrylate)
Authors: Horst Roland , Mertsch Rüdiger , Wolf B. A. 
Published: April 2003

AbstractThe viscosities of moderately concentrated solutions of poly(butyl methacrylate)—M̄w = 1820 kg/mol–in the thermodynamically good solvent toluene and in the theta solvent 2‐propanol were measured up to pressures of 2000 bar as a function of shear rate \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} in the temperature interval from 40 to 70°C. Both systems obey Graessley's equation so that it is possible to obtain the following rheological parameters in addition to the zero‐shear viscosity η0 from the dependences \documentclass{article}\pagestyle{empty}\begin{document}$ \eta (\dot \gamma ) $\end{document}. η can be split into an entanglement part ηent plus a frictional contribution ηfric, and the characteristic viscometric relaxation time τ0 becomes accessible. The present results demonstrate that the application of pressure raises the above parameters much less for good than for bad solvents. In contrast to ηfric (which can react differently to the application of pressure due to special circumstances) η0 and τ0 are always influenced to the same degree as T or p are changed. This result implies that the steady state shear compliance (τ0/η0) is independent of the variables of state irrespective of the thermodynamic quality of the solvent. For the good solvent the effects of temperature can be described by the Arrhenius equation, whereas the WLF equation has to be used for the bad one.
Microstructure of styrene‐methacrylic acid and styrene‐acrylic acid copolymers, 6. Relation of the glass transition temperature to the microstructure of (meth)acrylic acid‐styrene copolymers
Authors: S̀witala‐Żeliazkow Maria 
Published: April 2003

AbstractThe glass transition in acrylic acid‐styrene and methacrylic acid‐styrene copolymers prepared in benzene solution and in emulsion were investigated. A dependence of the glass transition temperature of the copolymer on the diad sequence distribution was found. There are two possible explanations of such a dependence: the microstructure determines the amount of intermolecular hydrogen bonds, and/or the microstructure of the copolymer, i.e. the diad sequence distribution, determines the intramolecular flexibility of the copolymer.
Polymerization of propene with zirconocene‐containing supported catalysts activated by common trialkylaluminiums
Authors: Soga Kazuo , Kaminaka Manabu 
Published: April 2003

AbstractThis paper reports on propene polymerization conducted with modified Kaminsky‐type catalysts activated by common alkylaluminiums. Several kinds of heterogeneous catalysts containing zirconocene were prepared by supporting Et[IndH4]2ZrCl2, iPr(Flu)(Cp)ZrCl2 and Cp2ZrCl2 on A12O3, SiO2, MgO, MgCl2, MgF2, CaF2 and AlF2 using an impregnation method. When Al2O3, MgCl2, MgF2, CaF2 and AlF3 were used as carriers, the resulting catalysts were easily activated by common trialkylaluminiums to give isotactic, syndiotactic and atactic polypropene in fairly good yields, whereas the other supported catalysts, combined with common trialkylaluminiums, did not show any polymerization activity. However, highly active catalysts were obtained by supporting the zirconocene compound on SiO2 that had been reacted with a small amount of methylaluminoxane. The use of C1‐containing alkylaluminiums always killed the catalyst activity.
Surface tension of liquid polysiloxanes having fluorinated alkyl side‐chains
Authors: Kobayashi Hideki , Owen Michael J. 
Published: April 2003

AbstractThe surface tension of viscous polymer liquids, viz. polysiloxanes having fluorinated alkyl sidechains, was evaluated based on the pendant‐drop method. The polysiloxane fluids studied are poly‐(3,3,3‐trifluoropropylmethylsiloxane), poly(3,3,4,4,5,5,6,6,6‐nonafluorohexylmethylsiloxane) (PNFHMS), poly(3,3,4,4,5,5,6,6,7,7,8,8‐tridecafluorooctylmethylsiloxane) (PTDFOMS) and poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10‐heptadecafluorodecylmethylsiloxane) (PHDFDMS). The surface tension of liquid poly(dimethylsiloxane)s was also examined as standard silicone fluids. The surface tensions of liquid PNFHMS, PTDFOMS and PHDFDMS were very low, as low as the value previously reported for poly(oxyhexafluoropropylene) fluids. Low‐ and hightemperature properties of these highly fluorinated polysiloxanes were also evaluated.
Studies on free radicals in popcorn and in normal polychloroprene
Authors: Fawcett Allan H. , Flockhart Brian D. , Poon Lai W. , Harrod Sydney 
Published: April 2003

AbstractThe electron paramagnetic resonance (EPR) spectrum from the radicals responsible for the growth of chloroprene popcorn has been observed as a broad singlet. During proliferous growth at 20°C the first‐order growth constant is 5,1 · 10−2 h−1, and the activation energy for the process is 38 kJ · mol−1. The rate of growth is reduced by exposure of the material to oxygen. Pure oxygen and air cause the EPR signal to diminish in intensity, as also do nitric oxide and nitrogen dioxide. The latter substance also reacts with the residues of chloroprene in popcorn and in normal bulk polychloroprene to form a nitroxide radical at a site that is a crosslink between two chains. The signal from this radical is an anisotropic triplet, characteristic of its restricted motion. On standing it becomes converted by protonation to a more complex pattern, and that signal diminshes in intensity in a reversible manner, probably because NO combines with the radical.
Solution behaviour of a liquid‐crystalline side‐group polymer
Authors: Fritz Lydia , Springer Jürgen 
Published: April 2003

AbstractDilute and semidilute solutions of fractions of a liquid‐crystalline side‐group polymer were investigated by means of size‐exclusion chromatography (SEC), static light scattering (LS), density and viscosity measurements. The mass‐average molar mass ranged from M̄w = 1 · 105 g · mol−1 to 1,5 · 106 g · mol−1. Large discrepancies were found between the molar mass determined through SEC and through LS. Strong interactions between the mesogenic groups can be assumed by the results of density and LS measurements. Due to the determined characteristic ratio of C∞ = 19,5 a similar chain stiffness as a poly(alkyl methacrylate) of equal length of the side chain is observed. In semidilute solutions an excess low‐angle scattering (ExLAS) occurs which increases at higher concentrations. The dependence of the reduced osmotic modulus [M̄w/(RT)](∂π/∂c)T on the parameter x = A2 · M̄W · c was studied.
Photodégradabilité de copolymères styrèniques comportant des motifs de chaîne α‐phényl et β‐phénylcétone. Polycétones issues de I'hydrolyse de polyméres et copolymères d'acétoxyphénylbutadiéne et de phényl(triméthylsiloxy)butadiènes
Authors: Guemra Kaddour , Casals Pierre‐François , Oulmidi Abdelkader , Mansri Ali , Reyx Danièle 
Published: April 2003

AbstractThe present work reports on the photodegradation of macromolecules (poly(styrene‐co‐carbon oxide)) having α‐phenyl and β‐phenylcarbonyl groups along the main chain. The photochemical behavior of polyketones containing β‐phenylcarbonyl groups and their comparison with the behaviour of a polyketone containing α‐phenylcarbonyl are expected to give useful informations. With this purpose polyketones constituted of 3‐oxo‐1‐phenylbutane‐1,4‐diyl units (i) regularly head‐to‐tail linked (I), (ii) included in polystyrene (II) or (iii) in poly(1‐phenylbutadiene) (III) and polyketone constituted of 3‐oxo‐2‐phenylbutane‐1,4‐diyl units (IV) have been considered. The synthesis of I by hydrolysis of polymers of 3‐acetoxy‐1‐phenyl‐1,3‐butadiene (2a) and of 1‐phenyl‐3‐(trimethylsiloxy)‐1,3‐butadiene (2b) have been tested: the polyketones I are proved to be more easily accessible from 2b and its polymer (3b) than from 2a and its polymer (3a). The polyketones II, III and IV have then been synthesized from the copolymer (4) of 2b with styrene, the copolymer (5) of 2b with 1‐phenyl‐1,3‐butadiene, and the polymer (8) of 2‐phenyl‐3‐(trimethylsiloxy)‐1,3‐butadiene (7), respectively. The photochemical behavior of these polyketones and copolyketones is in accordance with the previously observed regiospecific α‐phenyl‐side towards the β‐phenyl‐side fragmentation and shows that the expected photosensibilisation of the β‐phenyl‐side fragmentation by increasing phenyl to carbonyl ratio is not observed.
Ion‐conduction of lithium fluoroalkylsulfonates in oligo(oxyethylene)‐branched poly(phosphazene)
Authors: Tada Yuji , Sato Moriyuki , Takeno Noboru , Nakacho Yoshifumi , Shigehara Kiyotaka 
Published: April 2003

AbstractNovel organic‐soluble lithium salts, lithium 1,1,2‐trifluoro‐4‐methoxy‐1‐butanesulfonate (I) and lithium 3‐(2‐methoxyethoxy)‐1‐propanesulfonate (II), were synthesized. Their ionic conductivities were examined in a solid polymer matrix of endo‐methoxy oligo(oxyethylene)‐branched poly(phosphazene) (III) and compared with the ordinary hybrids of LiCIO4/III or LiSO3CF3/III. The ionic conductivity of I/III hybrid was as high as 2,2.10−5 S. cm−1 at 25°C, which is comparable to that of LiCIO4/III or LiSO3CF3/III hybrids. Although anions are the major carrier ions in the LiCIO4/III or LiSO3CF3/III hybrids, the lithium transport number of I/III hybrid was about 0.5 due to the larger size of the counter anion.
New polymer syntheses, 65. New terephthalic acids with aromatic substituents and thermotropic polyesters derived from them
Authors: Kricheldorf Hans R. , Bürger Rolf 
Published: April 2003

AbstractNew terephthalic acids with aromatic substituents were prepared in two different ways. A first attempt was made by nucleophilic substitution of dimethyl nitroterephthalate with phenoxide ions. The formation of phenyl methyl ethers is a significant side reaction in this procedure. The second method consists in the arylation of dimethyl 2‐(4′‐hydroxyphenylthio) terephthalate with activated fluoroaromatics. Insufficient electrophilicity of the fluoro compound is here the limiting factor. Thermotropic polyesters were prepared from 4,4′‐biphenyldiol and various arylthioterephthalic acids. It was found that increasing length of the aromatic side chain improve both solubility and meltability. All polyesters form a nematic phase above their melting point (Tm).
Water‐soluble polymers bearing biologically active residues, 2. Complexes of poly(ether‐ester)s with polyacrylic and polymethacrylic acids
Authors: Ignatova Milena , Manolova Nevena , Rashkov Iliya , Sepulchre Maurice , Spassky Nicolas 
Published: April 2003

AbstractThe complex formation between poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMA) with poly(ether‐ester)s such as poly[oxymaloyloxypoly(oxyethylene)]s (PMEGs) and poly[oxytartaroyloxypoly(oxyethylene)]s (PTEGs) as well as with their derivatives with the synthetic plant‐growth regulator 1‐naphthylacetic acid (NNA) was studied. Complex formation with PAA occurs below a critical polyether chain length for polymer‐polymer complexation. This peculiarity is discussed in view of the stabilizing effect of hydrophobization resulting from intramolecular hydrogen bonding. The hydrophobic 1‐naphthylacetyl groups of PMEG and PTEG esters are found to stabilize the polycomplexes even more. Derivatives with NAA as well as their complexes with PAA and PMA exhibit auxin activity.