Moisture absorption effect over time

Figure 8.3 shows the absorption over time at different RH and at a constant temperature of 34°C, while the effect of RH on maximum moisture absorption is shown in Fig. 8.4. The moisture absorption of PUPyBD045 rises continually with the increase in time until the specimen is saturated. The moisture absorption of a specimen tends to vary depending on the length of time for which it is exposed to moisture conditions, for example 300 minutes at 90% RH, over 450 minutes at 70% RH, and over 700 minutes at 60% RH. Figure 8.4 also shows that the maximum moisture absorption increases as RH increases, particularly at over 70% RH. For example, the maximum moisture absorption is only 4.5% at 70% RH, while it reaches 7.23% at 80% RH and 10.51% at 90% RH. This confirms that the moisture absorption at equihbiium is dependent on the RH, as higher RH...

Since extrapolation to a 50 year creep compliance or creep modulus depends critically on the short-term behavior, the moisture effects can potentially give significant errors, particularly if there is a one-time absorption of moisture into initially dry specimens. In tensile creep tests conducted over a two-year time period [7], the moisture fluctuations in the... 

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