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  • liquid crystal polyesters  (1)
  • tiered approach  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 683-695 
    ISSN: 1572-8943
    Keywords: degradation mechanism ; FTIR ; liquid crystal polyesters ; mass spectroscopy ; TG-MS ; thermal stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermal stabilities of two thermotropic liquid crystal polyesters were analysed by means of thermogravimetric analysis (TG), as a function of the chemical structure of the aliphatic spacer between the aromatic-triad mesogenic units. TG was combined with mass spectrometry to confirm that the degradation mechanism previously observed in a Fourier transform infrared study of the degrading polymers follows a β-cis-elimination process.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2932
    Keywords: atmospheric fate ; pesticides ; risk assessment ; tiered approach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Atmospheric fate of pesticides and their possible effects in ecosystems beyond the immediate surrounding of the application site are not actively considered in currently used regulatory risk assessment schemes. Concern with respect to atmospheric transport and subsequent deposition of pesticides in non-target areas is however growing. In this article the results of discussions on the possibilities of implementing atmospheric fate in regulatory risk assessment are presented. It is concluded that implementing atmospheric fate in regulatory risk assessment schemes is possible and that, from a scientific point of view, these schemes should distinguish between pesticides on the basis of both their possibility/probability to reach non-target areas and on their toxicity. This implies that application of the precautionary principle or use of intrinsic pesticide properties alone is not considered justifiable. It is recommended that the risk assessment scheme should follow a tiered approach. The first tier should be entered only if the existing regulatory risk assessment procedure, including a local PEC:PNEC calculation, has been passed and involves a test for the pesticide's total atmospheric emission potential, i.e. its potential for becoming airborne during and after application. The second tier, which is only entered if the total emission potential is higher than a certain trigger value, should consist of a PEC:PNEC calculation for regional off-site areas (10-50 km) (tier 2A). If the pesticide's atmospheric transport potential is expected to exceed a certain value, the PEC:PNEC ratio should also be calculated for more remote areas (〉1000 km) (tier 2B).
    Type of Medium: Electronic Resource
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