Sealants Tested

Twenty-four sealants of seven chemical types commercially available in Japan were selected for the study as shown in Table 5 [4]. The one-part silicone sealant was excluded due to cohesive failure early-on during the study. One sealant specimen according to Figs. 1 and 2 was prepared for each product. One-part sealants were allowed to cure for two weeks at 23°C and 55 % r. h., followed by two weeks storage at 30°C without humidity control. Two-part sealants were cured for one week at 23°C and 55 % r. h., followed by one week storage at 50°C without humidity control.

TABLE 3—Relationship between the degree of degradation (DoD) and the state of degradation (crazing).

Degree of degradation

Stale of degradation (Crazing)

25

Serious degradation

20

15

Medium degradation

10

Minor degradation

5

Slight degradation

0

No or very little degradation

TABLE 4—Experimental conditions for preliminary outdoor exposure experiment.

Switching frequency

Sealants2

Movement amplitude, VA

• None (fixed position)

• MS-2

• ±0 (static)

• Once / month

• PU-2

• ±15

• Once / week

• ±30

•Twice / week

FIG. 3—Dependency of degree of degradation on switching interval for different exposure times.