When the polymer material is exposed in the artificial climate chamber, the test temperature can be expressed in various ways. In addition to the air temperature in the test chamber indicated by the dry bulb humidity on the dry and wet bulb recorder, a blackboard hygrometer can also be used. The temperature indicated by the black standard thermometer and the white standard thermometer.
The temperature indicated by the blackboard hygrometer is the sum of the temperature of the heated air passing through the blackboard and the temperature rise irradiated by the light source. Because the blackboard temperature gauge is based on the black metal plate as the temperature sensing member and placed on the sample holder in parallel with the sample, and the black body absorbs a large amount of heat, the temperature indicated by the blackboard thermometer generally represents the sample. The highest temperature reached. Therefore, its purpose is mainly to reflect the approximate temperature of the sample surface in time and to control the upper limit of the sample temperature during the test.
The use of blackboard thermometers has been used for decades, and it can still be used in ASTM, JIS, DIN, ISO and other artificial climate test method standards. However, due to the improvement and application of various types of artificial climate chambers, there have been many developments and changes in the design of blackboard thermometers.
A commonly used blackboard thermometer consists of a stainless steel plate measuring approximately 150 mm in length, approximately 70 mm in width and approximately 1 mm in thickness. The side of the plate facing the light source should be capable of absorbing at least 90% of the total incident at 2500 nm with a black flat lacquer coating. The temperature measurement of the panel is performed by a blackened rod-shaped bimetallic disc sensor or measuring resistance sensor located in the center of the panel and firmly attached to the black exposed surface.
Different types of artificial climate chambers such as xenon light boxes, carbon arc light boxes, and fluorescent ultraviolet light boxes use different sizes and sizes of blackboard thermometers, which are generally determined according to the size of the sample holder.
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