ASTM D750:12(R2021) pdf free download – Standard Practice for Rubber Deterioration Using Artificial Weathering Apparatus.
6.7.6 The chamber air temperature shall be set at 44°C in equipment that provides for adjustment of the chamber air temperature.
6.8 Procedure for Exposure in bluorescent UV/ Condensation Apparatus (Practice G 154)—Un less otherwise specified, use the following operating conditions:
6.8.1 Use fluorescent UVA-340 lamps that comply with the spectral power distribution specifications in Practice G154.
6.8.2 The irradiance level shall be set at 0.77 W/(m2nm) at
340 nm in apparatus with irradiance control.
6.8.3 The exposure cycle shall be 8 h UV at an uninsulated black panel temperature of 60°C followed by a dark period of 4 h with wetting by condensation at an uninsulated black panel temperature of 50°C.
Note 3—Wetting by condensation may not be applicable to specimens of insulating materials having a thickness greater than 25 mm because of
inadequate heat transfer.
Note 4—The presence of ozone should be avoided since it can contribute to the crazing and cracking caused by light, heat, and moisture.
6.9.1 A mutually agreed upon specified number of hours, or
6.9.2 The number of hours of exposure required to produce mutually agreed upon minimum detectable changes in either the test specimen or an agreed upon standard sample.
7. Interpretation of Results
7.1.1 At the conclusion of the exposure interval the specimens shall be removed from the exposure test apparatus and examined visually for indications of crazing and cracking. The number and degree of cracks and crazes shall be reported by a mutually agreed upon method.
7.1.2 The tensile strength and ultimate elongation of these replicates shall be determined in accordance with Test Methods D412.
7. 1.3 For the purpose of comparison, tensile strength and elongation of duplicate unexposed specimens of the same material shall be determined at the time the exposed replicates are tested.
8. Report
8.1 In addition to the report requirements of Practice G 151. report the following additional information:
8.1.1 Any variations from the specified conditions,
8.1.2 Description and dimensions of specimens,
8.1.3 Number of cracks and degree of crazing or cracking of the specimens,
8.1.4 Percentage of elongation during exposure, if any,
8.1.5 Tensile strength in kilopascals (or pounds-force per square inch) before and after exposure,
8.1.6 Ultimate elongation at break before and after exposure,
8.1.7 Percentage loss in tensile strength as a result of exposure,
8. 1.8 Percentage loss in elongation at break as a result of exposure, and
8.1.9 Chlorine content of the water.
9. Precision and Bias
9.1 Precision—The repeatability and reproducibility of restilts obtained in exposures conducted according to this practice will vary with the materials being tested, the material property being measured, and the specific test conditions and cycles that are used.
9.2 Bias—Bias cannot he determined because no acceptable standard weathering reference materials are available.
10. Keywords
10.1 enclosed carbon arc; filtered open flame carbon arc; filtered xenon arc; rubber products; ultraviolet and ultraviolet! visible light aging; weathering