Crystallization characteristic strength values

PI(3,3 /4, 4 -ODPA/4,4 -ODA) was the smallest, as shown in the polyimides from BPDA and E was maintained at 10 Pa at 400°C as a result of crystallization. The E values of PI(2,3,3, 4 -ODPA/ 4,4 -ODA) and PI(2,2,3, 3 -ODPA/4,4 -ODA) decreased drastically at the Tg, and showed high thermoplasticity. PI(2,3,3, 4 -ODPA/ 4,4 -ODA) could be prepared as thin film because of its high thermoplasticity [43, 45]. As the thin film maintained high strength even after molten adhesion, PI(2,3,3, 4 -ODPA/4,4 -ODA) was used with APICAL AH ( Kapton-type polyimide) as the thin film on the Small Solar Power Sail Demonstrator "IKAROS". Wholly aromatic polyimides without aliphatic moietes have electron-beam-resistant and proton-beam-resistant characteristics in space environments. 

Figure 18.17 shows that the characteristics of the stress-strain curve depend mainly on the value of n the smaller the n value, the more rapid the upturn. Anyway, this non-Gaussian treatment indicates that if the rubber has the idealized molecular network strucmre in the system, the stress-strain relation will show the inverse S shape. However, the real mbber vulcanizate (SBR) that does not crystallize under extension at room temperature and other mbbers (NR, IR, and BR at high temperature) do not show the stress upturn at all, and as a result, their tensile strength and strain at break are all 2-3 MPa and 400%-500%. It means that the stress-strain relation of the real (noncrystallizing) rubber vulcanizate obeys the Gaussian rather than the non-Gaussian theory. 

With its determination carried out at constant ionic strength the pH, value, so obtained, provides an assessment of the acidity of the amphoteric ion exchanger. This pH, relatable to the average value of pKj and pK2 with Eq. (16), is very close to the value of the isoelectric point 0 )- Paries [105] has pointed out that the relationship between the lEP of a solid surface and the valency-effective ionic radii, when corrected for crystal field effects, coordination, hydration, and other factors, is quite good. He also has indicated that the broad probable lEP range characteristic of a cation oxidation state may be selected from the data in Table 2 as shown below. It is known that the lEP for amphoteric oxides is affected by the presence of impurities, crystallinity and the chemical species under investigation. 

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