Trends in composite research in Japan 200nm Figure 1l. Used multi-wall carbon nanotube for raising heat resistance of new polyimide MW-CNT(II) MW-CNT() 40 VGCF (D 330 5 CNF concentration(wt%) Figure 12. Upgrading of glass transition temperature(Tg) by loading of multi-wall carbon nanotube neat resin (TriA-PD)and 363C for composite with 14.3% weight MW-CNT through Route ll(the liquid route). A remarkable increase of 30 in Tg is identified [7]. The reason why dispersed MW-CNT increases the heat distortion temperature may be explained as follows: the dispersed Mw-CNT impedes the molecular motion polyimide network at elevated temperature. However, more research work would be required to prove that the suggested phenomenon is a true cause of higher Tg Although static properties are obtained, discussions are not given here. The other property improvements in this material are that MW-CNT shows some potential for controlling electric conductivity and electro-magnetic wave absorbability The third research topic concerning nanocomposites conducted in ACE TeC/JAXA is nano-clay dispersed composites [8] for improving gas barrier properties. This research topic is a basic part of the future cryogenic composite tank as a liquid
Trends in composite research in Japan 13 Figure 11. Used multi-wall carbon nanotube for raising heat resistance of new polyimide. Figure 12. Upgrading of glass transition temperature (Tg) by loading of multi-wall carbon nanotube to new polyimide (Tri A). neat resin (TriA-PI) and 363◦C for composite with 14.3% weight MW-CNT through Route II (the liquid route). A remarkable increase of 30◦ in Tg is identified [7]. The reason why dispersed MW-CNT increases the heat distortion temperature may be explained as follows: the dispersed MW-CNT impedes the molecular motion in polyimide network at elevated temperature. However, more research work would be required to prove that the suggested phenomenon is a true cause of higher Tg. Although static properties are obtained, discussions are not given here. The other property improvements in this material are that MW-CNT shows some potential for controlling electric conductivity and electro-magnetic wave absorbability. The third research topic concerning nanocomposites conducted in ACE TeC/JAXA is nano-clay dispersed composites [8] for improving gas barrier properties. This research topic is a basic part of the future cryogenic composite tank as a liquid
T Ishikawa Gas Flow (a) Montmorillonite Structure (b) Schematic of Gas Barrier Effect by Nanoclay Dispersion Easy to flake away Figure 13. Schematic of montmorillonite structure and possible gas barrier effect. 8 O p 3 phr 1.02.03.04.0 Time(sec)×1 Figure 14. Effect of nanoclay loading upon helium flux histor hydrogen reservoir for space vehicles. The nano-clay systems used are two types of modified montmorillonite. Nanofil-32 and Nanomer and schematic illustrations of their nano-structure and their function are shown in Fig. 13 18]. The surface modified clays are amenable to make organic/clay nanocomposites because of the weak bonding force between layers of montmorillonite. Dispersion occurs in the ompounding operation and the case where complete dispersion occurs is referred to as exfoliation. When nano-clays are exfoliated completely in a resin matrix, the result is a perfect nanocomposite. Typical diameter and thickness of exfoliated clay in the nanocomposites is about 10 um, and I nm, respectively, while the aspect ratio of this exfoliated clay was assumed to be 0.001. In this study, the base resin is a typical less viscous epoxy of Epikote 807 for better dispersion. Figure 14 de- picts the effect of nano-clay loading upon helium gas permeability in the present composites obtained by a helium leak detector [8]. If we convert the data into the diffusion coefficients and compare the experimental value and the theoretical
14 T. Ishikawa Figure 13. Schematic of montmorillonite structure and possible gas barrier effect. Figure 14. Effect of nanoclay loading upon helium flux history. hydrogen reservoir for space vehicles. The nano-clay systems used are two types of modified montmorillonite, Nanofil-32 and Nanomer, and schematic illustrations of their nano-structure and their function are shown in Fig. 13 [8]. The surface modified clays are amenable to make organic/clay nanocomposites because of the weak bonding force between layers of montmorillonite. Dispersion occurs in the compounding operation and the case where complete dispersion occurs is referred to as exfoliation. When nano-clays are exfoliated completely in a resin matrix, the result is a perfect nanocomposite. Typical diameter and thickness of exfoliated clay in the nanocomposites is about 10 µm, and 1 nm, respectively, while the aspect ratio of this exfoliated clay was assumed to be 0.001. In this study, the base resin is a typical less viscous epoxy of Epikote 807 for better dispersion. Figure 14 depicts the effect of nano-clay loading upon helium gas permeability in the present composites obtained by a helium leak detector [8]. If we convert the data into the diffusion coefficients and compare the experimental value and the theoretical