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  • 1
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Lower Critical Solution Temperature (LCST) of polyethylene (PE), polypropylene (PP), and ethylene-propylene block and random copolymers have been measured in heptanes. A thermogram related to the variation of the turbidity of the solution is obtained between 100 and 210°C. The temperature of the onset of the turbidity peak is defined as the LCST of the system. The width and the area of the turbidity peaks are tentatively associated with the polymer polydispersity and the amount of polymer involved in the phase separation. The thermograms of solutions containing both homopolymers show two distinct turbidity peaks situated at a 70°C interval. Correlations of molecular orientations in the concentrated phase, possible in PE systems but not in PP solutions, are at the origin of the lower LCST values for PE solutions. The LCST of copolymers are situated between those of the homopolymers but the dependence of the LCST on the copolymer ethylene content is different for block and random copolymers. Examples of thermograms are also given for mixtures of copolymers with PE and PP. By analysis of their thermograms, some commercial block EP copolymers were also found to contain PK and PP. This method seems well suited for characterizing polymer mixtures.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 1745-1757 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Rheological and small angle x-ray scattering (SAXS) measurements show that typical pressure sensitive adhesives prepared from block polymers of butadiene or isoprene with styrene maintain the domain structure of the block polymer well beyond the polystyrene domain Tg, but form homogeneous melts above a critical temperature, Tc. For the examples investigated, Tc lies some 20°C below the usual hot melt processing temperature. The extremely high resistance to creep of the adhesives at service temperatures is explained as being the result of viscous flow with the domain structure in a state of dynamic equilibrium, in which polystyrene blocks are detached from domains and reattached to others. A transition between nonequilibrium and equilibrium domain structures is revealed clearly by SAXS for one of the block polymers used in this work.
    Additional Material: 15 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 185-199 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The mixed cultures which were used were isolated from municipal sludge digesters, and the production of organic acids (acetic, propionic, butyric, etc.) from carbohydrates was tested. The behavior of the reference population (culture R) obtained directly from the sewage treatment plant, is compared to that obtained after three months in a plug-flow reactor (Gradostat fermentor) without pH control (culture A) and after six months with pH control (culture B). For culture B, the specific rate of acid production is related to the cell growth rate by (1/X)rp= 17 µ + 1.6 with a maximal acid concentration of 40 g/liter. The batch culture yields are improved from 0.36g/g for the initial culture (R) to 0.72 g/g for culture B after six months in continuous culture, and 0.8 g/g in plug-flow continuous culture. The productivity of organic acids reaches 1.7 g/liter·hr. It is suggested that the acidogenic fermentation, the first step of methanogenesis, is a potential process to produce acetic, propionic, and butyric acids.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 106 (1982), S. 169-180 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The dielectric behaviour of α-acetoxystyrene/styrene copolymers has been studied and the influence of polar substituents on the dielectric constant was investigated over a wide temperature and frequency range. A correlation of ∊′ with the polarity of the copolymer chains was established. Some of these copolymers could be usable in the capacitor industry.
    Notes: Cette étude a pour objectif général l'examen de divers copolymères à propriétés diélectriques améliorées. Elle concerne plus particulièrement la modification de comportement électrique apportée par l'introduction de groupements fortement polarisables sur des copolymères α-acétoxystyrène/styrène, les groupes polaires étant portés par le styrène. La synthèse et la caractérisation physicochimique de ces poly-mères réalisées précédemment permettent une corrélation structure-propriétés. L'examen des caractéristiques électriques (constante diélectrique, tangente d'angle de perte) a été effectué dans un large domaine de températures et de fréquences et a conduit à sélectionner des matériaux filmogènes susceptibles de convenir pour la réalisation de condensateurs.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1371-1378 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The intrinsic viscosities of some acrylic telomers prepared by redox catalysis were measured with an Ubbelohde capillary viscosimeter. The variation of density during dilution appears to be a very important parameter. Thus, the viscosimetric results become coherent according to Huggins' theory on polymers, and a calibration curve available for the whole range of molecular weights can be established.
    Additional Material: 4 Ill.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several telomers of vinyl alcohol with chloroform and diethyl phosphonate were prepared. Their DPn were measured by several analytical methods (elemental analysis, NMR spectroscopy, viscosimetry). Their small molecular size, their good water-solubility, and their very low acute toxicity allow to use them as drug-carriers in pharmacological applications.
    Additional Material: 8 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 59-65 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The present paper describes the synthesis of tetrakis [4-(1-phenylvinyl)phenyl]plumbane (1). It was found that “living” mono- or difunctional carbanionic polystyrenes are able to react with compound 1 to form star-shaped polymers or tetrafunctional crosslinked networks, resp., and it could also be shown that this polyfunctional lead compound can be used to prepare starshaped copolymers containing polystyrene and poly(methyl methacrylate) branches.
    Additional Material: 2 Tab.
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  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chlorides of carboxylic acids were grafted on telomers of vinyl alcohol. The yields of grafting were improved by increasing the temperature and the concentration of the reactants. In the range investigated, they do not depend on the DPn of the telomers, nor on the stoichiometric rates of the reactants. Therefore, the grafting rates are directly related to the initial conditions of the reaction. Modification of the telomers by treatment with ethylene oxide provides more soluble substances, but it does not affect the behaviour of the telomers in grafting reactions. Grafting of 1-(p-chlorobenzoyl)-5-methoxy-2-methyl-3-indolacetic acid (9) (indomethacin), an antiinflammatory drug, leads to potentially pharmacologically active telomers.
    Additional Material: 12 Tab.
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  • 9
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Systematic studies were performed on interpolymer complex formation between Poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO) in THF-water mixtures of different compositions. Viscosity behaviour during complex formation in mixed solvents was found to be entirely different from that observed by other workers in aqueous and in pure organic solvents. The result are interpreted in terms of, (a) preferential solvation of the polymer, (b) Probable change in conformation of the polyelectrolyte moleculer. (c) association of complex molecules in a medium of low dielectric constant, and (d) expected disordering of bound water molecules around PEO by THF. Irrespective of solvent composition, interpolymer complex of PAA and PEO was always found to have 1:1 unit mole ratio.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 2787-2797 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The anionic polymerization of 1,3 and 1,4-diisopropenylbenzene (DIB) was found to be characterized by a rather low ceiling temperature and by rather strong differences in reactivity between the two double bonds. At low degrees of conversion the polymers formed are essentially linear and carry one pendant double bond per monomeric unit. Branching and crosslinking can occur only at higher conversion. 1,3-DIB can be copolymerized anionically with α-methylstyrene. Grafting reactions were carried out on polymer backbones with pendant unsaturated groups, using two different pathways. The occurence of coupling reaction can be avoided by a proper choice of experimental conditions.
    Additional Material: 2 Ill.
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