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  • 1
    Electronic Resource
    Electronic Resource
    Functionalization of poly(organophosphazenes). 2. Modification of poly[bis(4-sec-butylphenoxy)phosphazene] by free-radical-initiated grafting of maleic anhydride (1992)
    s.l. : American Chemical Society
    Chemistry of materials 4 (1992), S. 1027-1032 
    Details
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cm00023a020
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  • 2
    Electronic Resource
    Electronic Resource
    Photochemical behaviour of poly(organophosphazenes). 14. Photooxidation of poly[bis(4-isopropylphenoxy) phosphazene] under accelerated conditions (1996)
    Springer
    Journal of inorganic and organometallic polymers and materials 6 (1996), S. 325-340 
    Details
    ISSN: 1572-8870
    Keywords: Poly(organophosphazenes) ; photooxidation ; poly[bis(4-isopropylphenoxy)-phosphazene] ; photodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The photooxidation of poly[bis(4-isopropylphenoxy)phosphazene] under accelerated conditions has been followed by FTIR and UV visible spectroscopic techniques. The main photooxidation products are acetophenone and phenol groups. In addition, acetone vapors have been detected by GC MS combined techniques concomitant with the IR spectral changes in the CH stretching region, suggesting a significant decrease in the isopropyl moieties. The presence of polymeric sequences having phenol groups under our conditions gives origin to further oxidation reactions due to electron transfer or radical recombination or to hydrogen abstraction reactions promoted by unhindered phenoxyl radicals. In addition, the absence of UV visible light, i.e., under thermooxidation reaction at 60° C has demonstrated that phenol groups are the main responsible of secondary oxidation products. The complexity of the photooxidation mechanism in the solid state for this polymer makes it difficult to determine a definitive degradation mechanism under both thermo- and photooxidative conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062513
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  • 3
    Electronic Resource
    Electronic Resource
    Photochemical behaviour of poly(organophosphazene)s, 12.Part 11: cf. ref.11 Photo-oxidation of catena-poly[bis(4-benzylphenoxy)-λ5-phosphazene] at short and long wavelengths under accelerated conditions (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 3047-3060 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this paper the mechanism of the thermo-and photo-oxidation of catena- poly[bis(4-benzylphenoxy)-λ5-phosphazene] films at short and long wavelengths has been followed under accelerated conditions using FTIR and UV-visible spectroscopic techniques. The decrease of the band at 1453 cm-1 and the simultaneous appearance of new bands at 3400 and 3481 cm-1, due to free and bonded hydroperoxides, show that the primary hydroperoxidation in this polymer occurs at —CH2— groups belonging to benzylic moietics. According to our previous paper, the bands observed in the carbonyl region at 1657, 1704 and 1725 cm-1 during photo-oxidation have been assigned to the formation of benzophenone, benzaldehyde and benzoic acids (dimmers), respectively. The formation rate of benzophenone groups increases during irradiation at long wavelengths (λ 〉 400 nm). Under thermo-oxidative condition (90°C), the benzophenone groups are the main oxidation products derived from hydroperoxide decomposition. In addition, the photooxidation of a film pre-thermo-oxidized for 500 h shows clearly that the benzophenone groups can generate aldehydes, benzoic acids and peracids. Crosslinking takes place in high yields by hydrogen abstraction occurring at both benzylic and secondary alcohol units. The regeneration of benzophenone groups has been evidenced during the photo-oxidation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1993.021941109
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  • 4
    Electronic Resource
    Electronic Resource
    Photodegradation of poly[ethylene-co-propene-co-(5-ethylidene-2-norbornene)] rubbers, 1. Reappraisal of the photo-oxidation mechanism under accelerated conditions (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 985-997 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this work the reexamination of the photo-oxidation mechanism of three poly(ethylene-co-propene-co-5-ethylidene-2-norbornene) (EPDM) terpolymers containing different amounts of 5-ethylidene-2-norbornene (ENB)System. name: 5-ethylidenebicyclo[2.2.1]hept-2-ene. (2-8 wt.-%) is discussed. The photo-oxidation depends on the initial content of ENB units in the chains. The formation of a band at 923 cm-1 is attributed to the CH out-of-plane deformation of a new double bond in terminal position in the ethylidene moieties. The presence of double bond migration suggests the formation of stable tertiary hydroperoxides which show a new band at 870 cm-1. The kinetic behaviour of a band with similar spectral pattern in the UV at 235 nm has been correlated with double bond migration. The identification of photoproducts both by 2,4-dinitrophenylhydrazin and SO2 confirms the proposed spectroscopic assignments. The gel measurements of the studied terpolymers, and some comparisons with a poly(ethylene-co-propene) (EPR) copolymer having a similar ethylene to propene ratio, suggest that the presence of ENB can strongly influence both the photo-oxidation and the crosslinking yields of these rubbers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950315
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  • 5
    Electronic Resource
    Electronic Resource
    Photodegradation of poly[ethylene-co-propene-co-(5-ethylidene-2-norbornene)] rubbers, 2.Part 1: cf. ref.9 Physical and dynamic-mechanical behaviour under accelerated conditions (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 999-1009 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The physical and dynamic-mechanical behaviour during the photo-oxidation under accelerated conditons of three poly(ethylene-co-propene-co-5-ethylidene-2-norbornene) (EPDM) rubbers with different contents of 5-ethylidene-2-norborneneSystem. name: 5-ethylidenebicyclo[2.2.1]hept-2-ene. (ENB) are reported. These results show the dependence of the glass transition temperature both on the ENB content and on the photo-oxidation time in accordance with network formation in the rubber matrix under accelerated conditions. The tensile experiments also show an increase of the elastic modulus as function both of ENB content and of photo-oxidation time. The Murayama and Mooney-Rivlin equations are applied to estimate the average molecular weight between two crosslinking nodes occurring in the rubber matrix during photo-oxidation with tensile and dynamic-mechanical experiments, respectively. Some correlations of physical and dynamic-mechanical changes with the proposed mechanism of photo-oxidation, due to the formation and reactivity of unsaturated groups, show that the crosslinking processes prevail over chain scissions.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021950316
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