2010 Volume 22 Issue 3 Pages 123-132
The accelerated weatherability methods and the chemical analytical methods of polyurethane sealants for buildings have been investigated. The chemical composition of sealants has been analyzed by using the solvent extraction technique. The amount of plasticizer has been measured using by n-hexane as an extraction solvent, and that of non-crosslinked poly-urethane and cross-linked polyurethane using by N,N-dimethylformamide as an extraction solvent. According to the results of the measurement of weathered polyurethane sealants, it was cleared that the amount of plasticizer decreased and the amount of non-crosslinked polyurethane increased with increas-ing weathering time. In order to develop a relevant accelerated weathering conditions, the factors of temperatures and humidity have been examined. The state of weathered sealant at temperature of 80°C and relative humidity of 5%RH was similar to that of outdoor exposure sealants, and the acceleration factor was calculated as about 16. Furthermore, analyzing by means of Py-GC/MS method, it was confirmed that the amount of diisopropylether of weathered samples was larger than that of an initial sample. The decomposition of crosslinked polyether-polyurethane was assumed to be caused by oxidative cleavage of the polyether segment.
