Weathering test artificial

Artificial Weathering Tests. Progress in this area has been achieved as chemists increased their understanding of the degradation mechanisms of polymeric systems. 

Artificial weathering tests in climatic chambers in accordance with the following specifications ... 

Air pollutants can cause damage to rayons. Artificial weathering tests have indicated that as the strength of the rayon decreases, its fluidity and reducing power as determined by copper number increase, but the carboxyl content decreases (62). When these tests were made with air contaminated with 0.1 ppm sulfur dioxide, an additional loss in strength was found over that caused when the weathering tests were made in pure air (62). 

After the pure loading tests artificial weathering tests are also required. In these weather exposure tests strips taken in the warp and weft directions are subjected to a standard climate. The exposure time is normally 1000 hours. After this time the strengths are determined. A time acceleration factor of 10 can be achieved. In other words, after 1000 hours of artificial weathering the strength loss after 10,000 hours can be determined. Alongside this are also calculation methods for the determination of the loss of... 

In artificial irradiation tests, for PP plates of varied stabiliser content, spectral sensitivity as weU as temperature dependence of irradiation-caused crack formation was quantified. For that purpose, samples were exposed both to artificial weathering tests at various constant temperatures and to spectrally resolved irradiation. The temperature dependence could be modelled by an Arrhenius fit. For fitting the spectral sensitivity, a plateau function was chosen. Subsequently, the stabiliser content was parameterised and extrapolated. 

However, first artificial weathering tests showed high time-to-failure durations for the black materials. Due to the limited project run time, efforts were focused on the faster degrading uncoloured materials. Results shown here are only from the uncoloured sample sets. 

Raining causes significant cooling. Figure 2.8. The surfaces of molded parts reach their maximum temperatures only toward the end of a dry period. Therefore, artificial weathering tests are performed with and without raining at elevated temperatures [201]. 

Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials, 2009... 

Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests... 

Test for low-temperature flexibility of latex sealing compounds after artificial weathering Test for extension/recovery and adhesion of latex sealing compounds after artificial weathering... 

Consequently, the errors of each kind of procedure are determined by the absence of simultaneously acting factors or supra estimation of applied conditions. The synergistic effects of environmental stressors determine correct results, which must be correlated with the chemistry of material. The repeatability of artificial weathering tests provides somewhat similar information, which is influenced by the material history. The outdoor exposure does not ever create identical intensities of degrading agents. The meaningful results are obtained by the simulation of natural... 

Table 1 depicts the main light sources used in artificial weathering tests and their characteristic wavelengths. Table 2 shows typical photochemical terms and their corresponding measurement units. Table 3 gives a detailed global radiation spectral distribution. 

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