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Natürliche und künstliche Alterung von Polymeren - Bericht über die XXII. Donauländergespräche
(2002)
Adaption of the Acid Dew and Fog (ADF) Test for Service Life Predicitons of Aircraft Coatings
(2003)
While artificial weathering is a long-established tool to investigate long-term behaviour of polymers at outdoor conditions, the use of chemiluminescence as a highly sensitive and broadly applicable sensor for the effected change is a recent addition. This combination of artificial weathering with chemiluminescence could already be successfully applied to differentiate and evaluate long-term stability of various real use polymeric building materials relatively to each other and promises to be a useful tool for a variety of other polymeric materials as well.
Adaption of the acid dew and fog (ADF) test for service life predicitons of aircraft coatings
(2003)
Adaption of the Acid Dew and Fog (ADF) Test for Service Life Predictions of Aircraft Coatings
(2003)
Grundsätzliches zur Frage der "UV-Beständigkeit" bzw. der "Lichtbeständigkeit" polymerer Werkstoffe
(2013)
Photo-oxidative ageing of polymers under defined exposure (UV, humidity) was investigated from two points of view: a) the ageing process Starts from the topmost surface and penetrates slowly towards bulk and b) radicals play an important role among ageing. Therefore, X-ray photoelectron (XPS) and electron spin resonance (ESR) spectroscopy were applied to show both, the progressive incorporation of oxygen during in-situ UV irradiation (XPS) and the formation of radicals (ESR) in the polymer. The intensity of ESR Signals served as measure for radical concentration. The Validation of this correlation was checked for polyethylenes (PE) equipped with different concentrations of Hostavin N30 UV stabilizer.
The outdoor weathering of polymers is mainly due to UV radiation, water, Pollution, humidity, temperature etc. To understand the effects of weathering, simulated tests need to be undertaken in lab scale. Such tests must be quite efficient and similar to the effects of natural weathering. This paper mainly focuses on the effects of UV radiation along with humidity on LDPE.
To determine a polymer’s spectral response of photo degradation, two main methods have been established. The so-called “filter technique” uses polychromatic radiation, which is filtered by a set of various sharp cut-on filters. This procedure provides separated reading points of an activation spectrum of the investigated material. With the "spectrographic technique” a specimen is irradiated with pectrally dispersed radiation, locally quasi monochromatically, and the local property changes.are related to the radiant exposure at the respective wavelengths. A third method, the irradiation of specimens with quasi monochromatic radiation behind interference filters, is rarely used.
These methods have advantages and disadvantages and therefore, there are limits for conclusions from these spectral data. Concerning the quasi monochromatic Irradiation of specimens the development of new UV radiation sources looks promising.
With the rapid development of inexpensive UV Light-emitting diodes (LEDs), new : sources of nearly monochromatic radiation in the UV ränge are available, even down to about 250 nm. To determine the spectral response, the use of such UV-LEDs in TO-18 ) and TO-39 metal cases combines the advantages of low cost and energy efficiency, stable spectral irradiance, temperature.and humidity control, larger specimen areas, and an easy and stable analysis.
Combinations of different UV LEDs are also discussed as replacement for xenon arc ' radiation sources, see patent application EP01528388A1.