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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 615-630 
    ISSN: 1572-8943
    Keywords: Fe3+-vanadyl phosphate ; NH3-TPD ; surface acidity ; TG/DTA ; vanadyl phosphate ; XRD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Iron(III)-substituted vanadyl phosphate, [Fe(H2O)]0.20VO0.80PO4·2.25H2O (FeVOP), has been prepared and characterized by XRD and TG/DTA analyses. The new compound is isomorphous with layered tetragonal VOPO4·2H2O (VOP), but it possesses a lower interlayer distance. Information on the reactivity and surface acidity of both VOP and FeVOP has been obtained by NH3-TPD experiments. The hydrated materials adsorb high amounts of NH3 (up to 2 mmol g-1). Different ammonia-containing phases are formed, characterized by lower interlayer distances in comparison with the NH3-free parent compounds. NH3 is intercalated between the layers without displacement of water. The materials dehydrated by heat treatment at 450°C retain the layered structure but adsorb NH3 only on the external surface. A wide variety of acid sites, from weak to strong, was observed. A mechanism is proposed for the NH3- acid sites interaction. SEM micrographs of VOP and FeVOP are shown.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 544-554 
    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 new industrial strategy in the polymer field requires the transformation of plastic “commodities” into “specialties”. From this point of view, polypropylene (PP) plays an important role both for its intrinsic properties such as high melting temperature, low density, high chemical inertness and for its capability to be produced with different morphological and molecular structures, to be modified with the addition of other polymers or mineral fillers and to be grafted with functional groups. The present range of special and reinforced polypropylene grades includes: elastomer-modified PP, elastomer-modified filled PP, glass fiber-reinforced PP, filled PP, esthetic filled PP, flame-retardant PP, and thermoplastic elastomers. New trends for significantly improving this family of polymers involve impact resistance, processability, durability, dimensional stability, elasticity, and surface properties. A positive answer to this complex emerging demand will put, as indicated, in this work, “special and reinforced polypropylene grades” in a position to successfully compete with technopolymers in some important, rapidly growing application sectors.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
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