Test methods were developed to duplicate the failure modes that occur to sealants during exposure in structures. The methods used a systematic approach to identify independent and synergistic effects of various aging factors on the durability of sealants. Two different types of sealants were studied, which were denoted as Sealants A and C. Sealants were evaluated for changed in modulus and stress relaxation. Changes in modulus were monitored over time in accelerated laboratory exposure over one month period while field exposure was evaluated every six months. Laboratory tests revealed that high temperature, cyclic fatigue deformation, or dry condition alone had a dramatic effect in increasing the modulus of Sealant A. For Sealant C, laboratory exposure showed that cyclic fatigue deformation in the absence of high temperature or moisture had no effect on properties, but combinations of cyclic fatigue deformation with temperature or/and moisture were found to be detrimental, resulting in extensive modulus decrease. The preliminary outdoor exposure results for Sealant A showed promising correlation in that modulus increase were observed for outdoor exposed specimens without any cyclic fatigue deformation and for laboratory accelerated specimens. In the case of Sealant C, sealants exposed to field conditions exhibited the same behavior, indicating that the accelerated test methodology provided an accurate indication of the service life of sealants in field conditions similar to those the sealant may have under actual use conditions. The present study has clearly showed the importance of designing experiments that enable effects of various aging factors to be systematically evaluated.
Proceedings Title: 2010 week of learning Pressure Sensitive Tape Council Tech 33
Conference Dates: May 12-14, 2010
Conference Location: Las Vegas, NV
Pub Type: Conferences
Sealants, durability, outdoor weathering, accelerated tests.