Artificial weathering devices

However, outdoor weathering tests are not quite reproducible due to the instability of the climate. Moreover, they are invariably slow, longer and longer exposure periods being required for the evaluation of new polymers with improved stability. This gradual increase in exposure time and a tendency towards more standardized methods has led industries to develop more powerful light sources and artificial weathering devices. 

Artificial weathering devices have helped clarify mechanisms and effects, and although there is no one-to-one correlation with outdoor weathering, they are still very useful for quick screening and for specification of PVC compounds. 

Figure 7 Comparison of sunlight versus artificial weathering device s spectral distribution. 

In 2005 at the Enropean Weathering Symposium (EWS), a paper was presented which repeated the Sedona exposure for a different material (commercial polycarbonate) which indicated two important results [3] First, that paper referenced a classical SEP approach. In the classical SLR approach, researchers utilize a three-step method. In step one, a model is created, typically in laboratory artificial weathering devices nsing DOE fnll factorial methods and/or multi-linear regressions varying the inpnt factors (typically including irradiance, temperature, and moisture). In step 2, researchers then obtain time slices of environmental variables from... 

Uniform and precise operation and maintenance of artificial weathering devices are essential. 

The most decisive technical problem with respect to weathering devices is to achieve an adequate simulation of solar radiation. When artificial weathering first began in the 1920s, the only source of intense radiation available was the carbon arc. The spectral energy distribution of this radiation bears but a faint similarity to that of solar radiation. 

The effects of temperature on the aging behavior of polymeric materials became especially clear when materials for the interior equipment of motor vehicles were tested. Since these are often exposed to solar radiation at high temperatures, the test conditions for artificial weathering must be selected accordingly. A specific black panel temperature is set in the weathering devices. 

Artificial rain in rapid weathering devices that also permit combined UV irradiation and spraying - preferably for materials with a large antioxidants loads [231]. 

The deficiencies in artificial weathering that led to poor or inconsistent correlation between such tests and outdoor exposures are due to the fact that the simulation of dynamic factors of natural weather (combination of radiant energy, thermal energy and humidity) is not possible in an artificial device [40]. 

There are several commercially available laboratory testing devices for artificial weathering of polymers and plastics for example [1762, 2343] ... 

Treatment of these samples with SF4 gas to convert the carboxylic acids produced in the weathering process into carbonyl fluorides showed [2, 11] that the acids are actually a mixture of aliphatic and aromatic acids (Figure 18.12). Aromatic acid species are by far the predominant ones, however. The origin of these acids will be discussed below in conjunction with the overall mechanisms of photodegradation. Aliphatic acid species were detected by GC/MS in the artificial device exposure of PECT [11], Note that the PECT copolymer produced more aromatic acids with the same exposure as PET but that the aliphatic acid production was several times higher for the PECT copolymer. The photo-oxidation of the co-glycol must be the reason for this difference. 

Artificial satellites, which are now used for communication, broadcast, weather forecast, etc., are equipped with a variety of semiconductor devices, which are often exposed to the high levels of radiation found in space. Such energetic particles, called cosmic rays, cause the degradation and malfunction of semiconductor devices, which lowers both the mission lifetime and reliability of satellites. Using ion beam irradiation facilities at TIARA, which have been uniquely adapted for simulating the radiation environment of space, we have... 

Aging by artificial means to obtain an indication on how a material will behave under normal conditions over long period. Also tests in which conditions are intensified to reduce the time required to obtain deteriorating effects, similar to these resulting from normal service conditions. Duplicating or reproducing weather conditions by machine-made means. Test in which the normal weathering conditions are accelerated by means of a device. 

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