Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Natural hazards 22 (2000), S. 225-268 
    ISSN: 1573-0840
    Keywords: Italy ; central Apennines ; active fault ; paleoseismology ; historical seismology ; seismic hazard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Quaternary tectonics and paleoseismologicalinvestigations have defined a reliable framework ofactive faults in the southern Umbria and AbruzziApennines. Two sets of NW–SE to NNW–SSE trending, 16to 33 km-long, normal and normal-oblique faults orfault systems have caused the displacement of LatePleistocene–Holocene deposits and landforms within theinvestigated sector. Available data on verticaloffsets indicate that both Late Pleistocene–Holoceneand Quaternary (since the later part of the EarlyPleistocene; 0.9–1 Ma) slip rates range between 0.4and 1.2 mm/yr (range 0.6–0.8 mm/yr preferred).Paleoseismological investigations show that recurrenceintervals for surface faulting events are alwaysgreater than 1,000 years and are usually greater than2,000 years. Both paleoseismological data andlong-term seismicity show that activation of theinvestigated faults may result in earthquakes ofM = 6.5–7.0. The extension rate across the two sets ofprimary faults ranges between 0.7 and 1.6 mm/yr.Horizontal seismic strain has been calculated to be0.5–0.6 mm/yr, based on the summation of the seismicmoment of M 〉 5.3 earthquakes which have affected theinvestigated area since 1200 AD. This value may belower than that inferred through geological data,probably because the seismological record reliable forthe addition of the seismic moments covers a too shorttime window (about 800 years) to be consideredrepresentative of the tectonic activity in theinvestigated area. This conclusion iscorroborated by the large recurrence intervalper fault (〉1,000–2,000 years) inferred frompaleoseismological analysis. A comparison of theactive-fault framework and historical-seismicitydistribution indicates that the entire eastern set ofactive faults has likely not been activated since 1000AD, thus indicating that the elapsed time since thelast activation for several faults of the investigatedarea may be greater than 1,000 years. In terms ofhazard, the highest probability of activation isrelated to the eastern set faults, due to theobservation that the elapsed time for some of thesefaults may be similar to the recurrence interval. Asan example, paleoseismological andarchaeoseismological data indicate that the elapsedtime for the Mt. Vettore and Mt. Morrone Faults may begreater than 1,650 and 1,850 years, respectively.These data may have significant implications for riskrelated to a number of towns in central Italy and tothe city of Rome. As for the latter, in fact,monumental heritage has suffered significant damagedue to earthquakes of M 〉 6.5 which originated in theinvestigated Apennine sector.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    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
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 94 (1981), S. 63-89 
    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: Es wird ein historischer Überblick der Entwicklung von Ziegler-Natta-Katalysatoren für die Propylenpolymerisation gegeben. Nach dem jahrelangen Einsatz von Titantrichlorid wurden in den 70er Jahren neue Katalysatoren der sogenannten zweiten Generation eingeführt, die schneller wirken und zu kristallineren Produkten führen. Ausführlich wird auf die neuere Entwicklung zu Katalysatoren der „dritten Generation“, speziell auf ihre morphologischen Eigenschaften eingegangen. Diese Katalysatoren ergeben sehr hohe Ausbeuten, sterisch sehr regelmäßige Polymeren und eröffnen Möglichkeiten zur Vereinfachung der Polypropylentechnologie und Energieeinsparung. In Zukunft wird die Polypropylenherstellung nur aus der eigentlichen Polymerisationsstufe bestehen, und es wird keinerlei Nachbehandlung wie Zentrifugieren oder Extrudieren erforderlich sein.
    Notes: A historical survey about the development of Ziegler-Natta catalysts for polymerization of propylene is given. After having employed catalysts based on titaniumtrichloride for several years, in the 70's catalysts of the so-called second generation were introduced, which are more effective and yield products of higher crystallinity. Catalysts of the so-called third generation and their morphological properties are extensively dealt with. These catalysts give high yields and highly stereoregular polymers and enable simplification of polypropylene technology and energy saving. In the future polypropylene manufacturing will probably consist only of the polymerization steps with no need for centrifuging, extruding or another post-treatment.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 39 (1988), S. 81-90 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Neue Katalysatorsysteme für die Synthese von Polypropylen und Propylencopolymeren wurden entwickelt. Der Wachstumsmechanismus der morphologischen Strukturen der Polymere und einige Besonderheiten des Prozesses werden beschrieben. Einige Eigenschaften der erhaltenen Polymere und Copolymere werden vorgestellt, und die Vorteile und zukünftigen Entwicklungen dieser Technologie werden diskutiert.
    Notes: New catalyst systems for the synthesis of polypropylene and polypropylene copolymers have been developed. The growth mechanisms of morphological structure of the polymers and some features of the process are described. Some properties of the obtained homopolymers and copolymers are presented, and the advantages and future developments of the process technology are discussed.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...