ASTM D518-99 pdf free.Standard Test Method for Rubber Deterioration—Surface Cracking.
Place an identification mark on the broad end of eachtest specimen, using materials that will not have a deleteriouseffect on the specimens during aging and that shall not extendbeyond the area covered by the aluminum angle strips.
Superimpose upon the specimen a template conform-ing to the dimensions shown in Fig. 4, and mark the specimenwith a sharp pointed pencil to conform with the holes in thetemplate.After the specimens have been mounted,mount thealuminum shield on each of the long sides so that the tacksholding the specimens and the markings are covered.
Expose the extended specimens to the weather andsunlight at an angle of 45° with the horizontal facing south,preferably on a roof of a building; or they may be exposed ina cabinet having an atmosphere in which the ozone content iscontrolled, as described in Test Method D 1149.
Take note of the warnings in Test Method D 1149regarding the hazardous nature of ozone if an ozone cabinet isused.
Record the datc on which the tests were begun,andexamine the specimens daily thereafter，for the effects ofozone.Observation shall be made with a 7-power magnifyingglass. Record the time of the appearance of the first minutesurface cracks on each specimen.If desired, the exposure maysubsequently be continued for the purpose of observing the rateof growth of the cracks or the development of any characteristic or unusual surface effects.
Loop the test specimens until their ends meet and theninsert these ends between the paired wooden or aluminumstrips until they are flush with the underside of the strips. Theminimum distance between the specimens shall be 6 mm (0.25in.).Clamp the wooden strips together by means of machinescrews so that the specimens are firmly held in place. As aresult of this procedure，25 mm (1 in.) of each end of thespecimen will be covered by the wooden strips, which will actas a protective shield. The remaining 43 mm (1.75 in.) of thespecimen shall form a loop having a varying elongation alongits length, as shown in Fig.2.Mount the rack of clamped specimens on the cross-picces attached to the base panel by passing the protrudingmachine screws of the panel between the paired wooden oraluminum strips and fastening them with nuts and washers, asshown in Fig. 3.
Expose the looped specimens to the weather andsunlight at an angle of 45° facing south, preferably on the roofof a building; or they may be exposed in a cabinet having anatmosphere in which the ozone content is controlled,asdescribed in Test Method D 1149.ASTM D518 pdf download.