Studies concerning the durability of sealants are often made by comparing the different polymer backbones e.g. silicone vs. polyurethane or silane-terminated polymers. At the 2015 FEICA conference the author presented a comparison of different sealant types after accelerated weathering according to ISO 19862. In order to establish whether accelerated weathering leads to similar results as real aging, the same tests were 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, UV stabilizers, heat stabilizers etc., to various polymer bases has similar effects outdoors as in the UV chamber. 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 in order to get more detailed information about changes of the mechanical properties. These tests were done for outdoor weathering as well as for artificial aging in the UV chamber.
On the basis of the tests outlined above, the author will elaborate on the behavior of various formulations and technologies concerning durability as well as aesthetic aspects. The focus is hereby on tests including cyclic movement and the comparison of artificial aging and outdoor weathering processes.