Accelerated UV tests

Accelerated UV tests provide an alternative and generally much more rapid means of measuring the effects of light on polymers under consistent and reproducible conditions. The UV light is generally provided by xenon arc lamps and some modern UV exposure cabinet provide a very rapid assessment of polymeric materials (Figure 3.4) and correlate well with environmental exposure. Any element of the environment can be incorporated into a weatherometer . For example, relative humidity may be varied and an alternating water spray can be incorporated to simulate rain. As has already been noted this surface treatment may... 

Accelerated UV tests are normally conducted slightly above ambient temperatures (30-35 °C) and are generally more useful for assessing the durability of domestic and office equipment than outdoor tests. However, the technique used has to be calibrated with long-term performance in the user environment. 

Accelerated UV tests prove that material color remains unaffected and its retention is clearly superior to UV stabilized, flame retarded ABS. Selected grades have UL746C weath-erability listings. 

Tensile strength, flexural modulus, puncture strength, scratch, and marking resistance at low, as well as at elevated temperatures, are better than those of synthetic leathers present in the market. Outdoor ageing and accelerated UV tests indicate that this material can well overcome the severe conditions produced by the tendency to increase the oblique angle of car windshield. Same characteristics of the TPO based synthetic leather are reported in the Tables 6-8. 

The above-mentioned codes contain requirements for accelerated durabiUty tests. In addition, interlayer manufacturers and laminators expose test samples for several years under extreme weather conditions, eg, the Florida coast and Arizona desert. The laminated products weather extremely well, with no change in the plastic interlayer. Occasionally, clouding is noted around the edges when exposed to high humidity for long periods, but this is reversible. Colored areas of PVB laminates may fade while subjected to extensive uv/solar irradiation, which could cause an appearance issue. This has not, however, been shown to alter the laminate s other performance properties. 

A systematic investigation of intrinsic chemical stability was carried out on devices specially designed for high power applications [7]. For this purpose, accelerated ageing test procedures were developed for nc-DSCs and it turned out that, to first order, a separation can be made between the effects of visible light soaking, UV illumination and thermal treatment on long term stability. 

An additional option for accelerated photostability testing is irradiation without filter inserts. In this case, one has to take into account that the different wavelength ranges will influence the types, degradation rates, and the quantitative amounts of products produced. The formation of artifacts, other than those formed under terrestrial short UV irradiation and window glass filtered daylight must always be considered. 

A series of accelerated exposure tests was performed to investigate the effect of UV radiation on the coating material, the stress-strain state in tension and shear, and the color fastness of the coating material. The tests were carried out according to ASTM Standards ASTM D4329, G151 and G154. 

This practice describes the outdoor-accelerated-exposure testing of plastics and plastic-made products using Fresnel reflecting concentrator. The latter uses the sun as a source of UV and longer wavelength radiation and involves a system of plane mirrors focused on an air-cooled target board on which the test specimens are mounted. The three basic exposure methods are as follows ... 

The light sources commonly used for laboratory-accelerated weathering tests include filtered xenon arcs, two types of filtered carbon arcs, fluorescent UV lamps, and metal halide lamps. The spectral power distributions are shown in Figures 8.3 through 8.6 in comparison with solar radiation. The spectral emission characteristics of the sources differ significantly in both the UV and visible regions. 

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