Comparison of the Weatherabilities of Different Types of Sealants with Various Stabilizers Based on Outdoor Weathering with Cyclic Movement for 12 and 24 Months

摘要

Studies concerning the relative weatherabilities of sealants are often made by comparing the different polymer backbones, e.g., silicone versus polyurethane or silane-terminated polymers. In 2014, ASTM Committee C24 presented a comparison of different sealant types after accelerated weathering according to ISO 19862. To establish whether laboratory-accelerated weathering leads to similar results as environmental aging, the study was repeated with the same products in outdoor weathering with also once-a-week cyclic movement. The tests were carried out in Southern Germany in moderate climate conditions. Another goal of these tests was to find out whether movement and weathering according to ISO 19862 gives results comparable to those of outdoor weathering. It was also of special interest to determine whether the addition of adhesion promoters, ultraviolet stabilizers, heat stabilizers, etc., to various polymer bases has similar effects outdoors as in the laboratory-accelerated weathering device. Furthermore, the tests showed whether the performance of the final formulation is different in outdoor weathering. In addition to the pass-fail criteria according to ISO 19862, the change in modulus and the elastic recovery were determined regularly to obtain more detailed information about changes in the mechanical properties. These tests were done for outdoor weathering as well as for artificial aging in the laboratory-accelerated weathering device. On the basis of these tests, this paper presents the behavior of various formulations and technologies concerning durability as well as aesthetic aspects. The focus is on tests that include cyclic movement and the comparison of artificial weathering and outdoor weathering processes.