Dex Plots

Figure 7(a) shows the dex scatter plot of the data. The vertical axis is the modu­lus ratio in, and the horizontal axis depicts the four exposure variables, i. e., three-level temperature, four-level cyclic movement, four-level RH, and two – level UV exposure. It can be seen that there is no apparent relationship between

FIG. 6—Dependence of modulus ratio on max strain and temperature for specimens exposed to UV radiation and high RH (75 %).

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FIG. 7—(a) dex scatter plot and (b) mean plot of data for various exposure conditions. Although no obvious relationship between the modulus ratio and exposure variables is present in the dex scatter plot, the mean plot reveals that all exposure variables seem im­portant for modulus decrease.

the modulus ratio and the four exposure variables due to large differences in the modulus ratio for a given setting of exposure variable.

In contrast, the dex mean plot [Fig. 7(b)], which shows the mean values of the modulus ratio for various levels of each exposure variable, reveals that all exposure variables have an effect on modulus decrease. A relation between the change in modulus ratio and exposure to the various environmental variables is evident, suggesting that the presence of UV radiation, an increase in tempera­ture, a larger cyclic movement, or increased RH leads to a decrease in the modu­lus ratio for the particular sealant tested here. The effects of all of the exposure variables on the modulus decrease are evident, with cyclic movement and UV being the most important factors.