Weatherometer

An appraisal of artificial weathering methods was given in a report by Hoey and Hipwood who described the effectiveness of various weatherometer tests such as are described in BS 3900 Part F3 and ASTM 42 1964 (now ASTM G23 1989). Although these tests simulate atmospheric exposure it is not possible to obtain a direct correlation owing to variation in outdoor exposure conditions from place to place, but they serve a very useful purpose in providing a preliminary sorting of paints that can then be tested in the field. 

Weatherometer-Induced Discoloration of 6PPD- and TBTT-Containing Styrene-Butadiene Rubber (SBR)... 

A number of recent studies have been concerned with the effects of commercial heat stabilizers on the photodegradation of PVC. During irradiation at room temperature under air with 253.7-nm light, several dialkyltin dicarboxylates were found to increase the rates of the photooxidation and cross-linking of the polymer (62). However, at 0°C under air in a sunshine weatherometer, photooxidation was shown to be retarded by certain dibutyltin dicarboxylates (63). The latter result was also obtained in experiments involving the use of dibutyltin maleate with irradiation in the (280-400)-nm wavelength region at 38°C under air (50,51,64, 5,66). 

Photooxidation at 0°C ih a sunshine weatherometer has been found to cause preferential destruction of the methylene groups in PVC (94). On the other hand, preferred removal of the chloro-methylene groups was observed in an earlier photooxidation study carried out at 30°C with 253.7-nm irradiation (96). A possible explanation for this apparent contradiction is that the use of 253.7-nm light enhanced the relative importance of photoinitiation involving C-Cl homolysis. 

Films, for both mechanical and spectroscopy studies, were affixed to the specimen panels of the weatherometer. Upon completion of the UV exposure, which occurred at 37°C 1°C in the presence of air, the films were removed and kept at room temperature in the dark for at least 24 hours in order to remove any volatile oxidation products. 

G.A. Van der Doelen, K.J. Van den Berg, and JJ. Boon, A Comparison of Weatherometer Aged Dammar Varnishes and Aged Varnishes from Paintings, in Proceedings of the Conference Art et Chimie La couleur, J. Goupy and J.P. Mohen (Eds), Paris, France, 1998, CNRS Editions, Paris, 2000, pp. 146 149. 

Weatherometer test, 18 72 Weaton-Najarian zinc condenser, 26 577 Weaving, 11 178 cotton, 8 17-18... 

SKS-30-1 = styrene rubber containing methacrylic acid. Tests performed in an Atlas weatherometer for 100 h. 

In order to investigate the UV Stability of ABS, specimens were exposed in a weatherometer. The ambient temperature of 30°C ensured that the mechanism of UV degradation was not interfered by thermal effects The specimens were exposed under accelerated conditions for 3 months, with periodic assessments of their performance (62). 

Figure 3. Weatherometer aging of transparent saturated acrylic...

Outdoor aging is currently being conducted on these polymers, and while accelerated aging may have limited value in predicting long term outdoor exposure, the accelerated aging studies of Jordan et al. (9) with poly (methyl methacrylate) copolymers and homopolymers indicated that a 2000-hour carbon-arc weatherometer period was a realistic exposure to screen the relative changes to be expected in about a two-year period in an outdoor environment—e.g., Florida or Arizona. 

The effectiveness of several surface treatments is illustrated in Table I. The springwood erosion (in microns) is determined using a compound reflected-light microscope at 140X. End-matched samples are used for comparison. Accelerated exposure was in a weatherometer with exposure cycles of 20 hours light,... 

Table II. Springwood Loss of Western Redcedar After Accelerated Weathering (480 Hr In The Weatherometer) As Related to Chromium Metal Concentration...

Xenon-arc Weatherometer (Filtered, 6000 watts) Model 60-WR samples were exposed according to standard procedure, except no water spray was used. The xenon lamps used were preaged for 100 hours. 

Colorfastness to Light. Specimens were exposed to continuous light provided by the carbon arc lamp of a Weatherometer for various periods of time, ranging from 30 min to 40 h. It was necessary to evaluate the color change at more frequent intervals than those suggested in the test method 16A-1977, because studies have indicated silks sometimes lose color within an hour of exposure (7). 

Calculated from L,a,b values on a Hunter color difference meter (average of six readings on each sample) exposure in Weatherometer is listed in kilojoules per square meter (ambient dry bulb temperature, 85°F 3° wet bulb temperature, 70°F 4°, black panel temperature 100°F % relative humidity, 50 8%). Each 110 kJ/m2 corresponds to about 20 h exposure to noon sunlight conditions. 

To determine whether or not film thickness had any effect on protection of the wool fabrics, various 5- and 12-mil-thick cellulose acetate films were cast and used to cover fabrics exposed in the Weatherometer. Although it was possible to obtain films of good clarity and a minimum of surface defects at 5- and 8-mil thickness, two castings were necessary to obtain 12-mil-thick films. Attempts to prepare a 12-mil-thick film in a single cast resulted in pronounced cratering and poor clarity. 

Atlas Fade-ometer and Weatherometer, Bulletin No. 1300 C, Atlas Elec-... 

Figure 11.6. QUV-A weatherometer testing (75-p.m sample thickness) relationship of days to failure (50% elongation) to carbon black type and loading.

Fade and weather resistance can also be evaluated using laboratory test chambers, fadometers, and weatherometers, designed to simulate a variety of actual environments in an accelerated fashion. The types of tests are classified according to the nature of the light source ... 

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