Fluorinated-pitch

Fig. 1. TEM image of fluorinated pitch-based fiber (HTT-P75), C3F (reproduced with permission from Carbon, 33 (1995) 1339 [18]).

As mentioned in the last section, three types of fluorinated pitches, yellowish white powdery solid (S-type), colorless transparent resin (R-type) and liquid (L-type),... 

Fig. 2. F/C atomic ratio of solid type fluorinated pitch as a function of the fluorination temperature.

Maeda considered that the formation reaction of fluorinated pitch is kinetically written by... 

Heat treatment of the S-type fluoride in a fluorine atmosphere Based on the results above mentioned, Fujimoto et al. developed a new fluorination procedure in order to prepare the perfluorinated pitch, and obtained two types of other fluorinated pitches [23,24], The new process is by the heat treatment at 200-400°C of S-type of fluorinated pitch prepared at relatively low temperature in a fluorine atmosphere. They firstly fluorinated the mesophase pitch at 70°C for 10 h (first step for the preparation of S-type fluorinated pitch) and then heated up to a selected temperature between 200°C and 400°C, and maintained this temperature for 12 h (second step for the heat-treatment of fluorinated pitch). Thus, they obtained two kinds of fluorocarbons, a transparent resin (R-type) and a liquid (L-type). L-type is a viscous fluid containing some volatile materials and the viscosity gradually becomes higher when it is kept for a few weeks in an air atmosphere even at ambient temperature. They reported that the R-type was obtained in the nickel boat in the heating zone and L-type at the bottom of the vertical reaction vessel which was cooled down by the water. Therefore, it is likely that the liquid fluorocarbon is formed by the vaporization of some component contained in the S-type fluoride or decomposition reaction during the heat treatment of the S-type fluoride. The yields of these compounds depends on the heat treatment temperature. In Fig. 3, the yields of the R-type and L-type fluorocarbons are plotted as a function of the heat treatment temperature of the S-type fluoride. The yield of the former decreases with increase of the heat treatment temperature and finally, at 400 C, it can not be obtained at all. On the other hand, the yield of the latter increases with increase of temperature and it is selectively obtained at 400°C. 

Weight of the pristine solid type fluorinated pitch... 

Fig. 4. Typical X-ray diffraction patterns of mesophase pitch, fluorinated pitch and (CF) (A) mesophase pitch (B) solid type fluorinated pitch prepared at 70°C (C) graphite fluoride, (CF) . (Quoted from H. Fujimoto, A. Mabuchi, T. Maeda, Y. Matsumura, N. Watanabe, H. Touhara, Carbon, 30 (1992) 851, with permission).

Fig. 5. Cls ESCA spectra of solid type fluorinated pitch, (CF) and PTFE (A) solid type fluoride prepared at 70 C (B) graphite fluoride, (CF) (C) PTFE. (Quoted from the poster material of Ref. [18]).

The characteristics of fluorinated pitch (Pitch Fluoride) [20-25,38-44] include high water repellency, high solubility in fluorine-containing solvents and ease of micronization. We examined the characteristics of solid, glassy and liquid... 

Plating bath composition Fluorinated pitch 50 g/1 Nickel sulfamate 360 g/1 Nickel chloride 45 g/1 Boric acid 30 g/1... 

Figure 17 shows the relationship between current density and amount of codeposited fluorinated pitch (vol%). As the current density increased, the amount of... 

Fluorine compounds have an oxygen affinity. Accordingly, application of the fluorinated pitch-deposited film to an oxygen enrichment membrane material was examined. The compound was deposited on a porous substrate under the following deposition conditions. 

Fig. 19. Dependence of contact angle with water on the contents of co-deposited fluorinated pitch in the composite films.

Compared with PTFE, fluorinated pitch has a higher oxygen transmission constant, but a lower separation ratio a. 

Conventional humidity sensors of the electric resistance variable type use hydrocarbon polyelectrolyte as a moisture sensing material. Therefore, the sensors usually have insufficient heat resistance, and cannot be used at temperatures of 60°C or more. Another problem is that they deteriorate when in contact with cigarette smoke and oil contained in the air [64,65]. When the fluorinated pitch-deposited coating was breathed upon, the electrical resistance quickly decreased, but electrical resistance quickly recovered when this action was stopped. Then, how to develop a humidity sensor excelling in humidity response sensitivity, heat resistance and durability was attempted [66]. Two kinds of comb-like electrodes with different electrode gaps were made, and a thin film was formed on the surfaces by vacuum deposition of fluorinated pitch. The obtained fluorinated pitch sensors were left at rest in a thermostatic chamber, and electrical resistance was determined under the following conditions. 

Applications using reactivity offluorinatedpitch 18.4.4.1 Colored fluorinated pitch [67]... 

Colored fluorinated pitch is extracted by using hexafluorobenzene (CeFg). 

The extract is concentrated through vacuum distillation and dried to obtain colored fluorinated pitch. 

This reaction yielded colored fluorinated pitch from white powdery solid fluorinated pitch. Various products produced in this manner have such large contact angles of water drops as 145° or more. Figure 21 shows the results of H NMR measurement... 

Fig. 21. H NMR spectra of methylene blue before (i) and after (ii) reaction with fluorinated pitch.

In addition to the above-mentioned applications, we have examined and developed other applications based on the physical properties of fluorinated pitch. First, its... 

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