STRESS MONITORING IN THIN POLYMER-COATINGS USING TIME-RESOLVED FLUORESCENCE

Stress monitoring in thin polymer coatings was monitored using time re solved fluorescence from organic molecules. The decay time of fluoresc ence from an organic molecule in a uniaxially stretched polymer coatin g decreases with increasing tensile stress. The substance 9-methylanth racene (9-MeAn) is an effective dye for detecting internal stresses up to 10 MPa. Compared with the traditional bimetallic method, time reso lved fluorescence of 9-MeAn gave reliable values for internal stresses in a thin polymer coating. The internal stress in a polymer coating c ured on a glass plate was measured during exposure to an outdoor weath ering test. The internal stress diminished significantly in three days . The decrease in the internal stress was caused mainly by light irrad iation. Because 9-MeAn degraded in sunlight, it was a useful probe for stress monitoring only for periods less than two weeks.