β Scribed by Ching-cheh Hung; Donald Kucera
No coin nor oath required. For personal study only.
Halogenated graphite CBrJ, (1 < y/x < 10) was made by exposing graphite materials to either pure Br, or an I,/Br,/HBr mixture to initiate the reaction, and then to iodine vapor containing a small amount of Br,/HBr/IBr to complete the intercalation reaction. Wetting of the graphite materials by the I,/Br,/HBr mixture is needed to start the reaction, and a small amount of Br,/HBr/IBr is needed to complete the charge transfer between iodine and carbon. The interplanar spacings for the graphite materials need to be in the 3.35 to 3.41 A range. The X-ray diffraction data obtained from the halogenated HOPG indicate that the distance between the two carbon layers containing intercalate is 7.25 A. Electrical resistivity of the fiber product is from 3 to 6.5 times the pristine value. The presence of a small amount of isoprene rubber in the reaction significantly increased the iodine-to-bromine ratio in the product. In this reaction, rubber is known to generate HBr and to slowly remove bromine from the vapor. The halogenation generally caused a 22% to 25% weight increase. The halogens were found uniformly distributed in the product interior. However, although the surface contains very little iodine, it has high concentrations of bromine and oxygen. It is believed that the high concentrations of bromine and oxygen in this surface cause the halogenated fiber to be more resistant to structural damage during subsequent fluorination to fabricate graphite fluoride fibers.
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