Sugio Otani

Carbonaceous Mesophase and Carbon Fibers

Abstract I esteem it a great honor to have been invited to this meeting. On the other hand, I am a little confused by the invitation, because I am not a specialist in liquid crystals but only in carbon materials. The main reason why I have been invited to this meeting is, I think, probably because I first originated the fundamental procedure for producing carbon fibers from pitches and have been developing this field for the past 15 years. I also presume that the preparation of carbon fibers from mesophase pitches especially claims your interest. From these points of view I have prepared the subject matter of my lecture.

Magnetic Properties of Triarylmethane Resins

Abstract Triarylmethane resins dehydrogenated by irradiatation exhibited the ferromagnetic behavior.

Carbons formed catalytically by nickel in phenolic resin carbon: Oxidation by Simon's reagent and HNO3-H2SO4

Abstract A graphitic carbon (G carbon) and a turbostratic carbon (Ts carbon) were prepared by the catalytic graphitization of a phenolic resin carbon using bulk and finely dispersed nickel respectively at 1673 K. The nickel was removed at 1673 K using chlorine and the carbons were subjected to heat treatment temperatures (HTT) of 1773, 2273 and 2773 K. For reference, non-graphitizable resin carbons (A carbon) and graphitizable coal-tar pitch carbons (Tp carbon) were prepared at these HTT and examined by X-ray diffraction and Raman i.r. The twelve carbons were oxidized in Simons reagent and HNO 3- H 2 SO 4 (5:1) at 351–393 K. Their surfaces were studied by SEM. Structural order in the carbons decreases in the order G > Ts > Tp > A . Using Simons reagent the reactivity order is G > Ts > Tp > A and for mixed acid A > Ts > Tp > G . Activation energies are a maximum for A carbons using Simons reagent and G carbons using mixed acid. The mechanisms of oxidation in the two media are different. Intercalation may be important in oxidation by Simons reagent.

Catalytic graphitization of a phenolic resin carbon by nickel (~100 μm): Selective gasification of three resultant components as studied by SEM

Abstract A phenolic resin carbon containing nickel particles, ~100 μm diam., was graphitized to 2773K for 1 h. This treatment created within the specimen three structural components known as graphitic ( G ), turbostratic ( T s ) and matrix ( A ). The graphitized carbon was oxidized by carbon dioxide, HNO 3 -H 2 SO 4 mixed acid and Simons reagent and topographical changes were monitored by SEM. The CO 2 gasified preferentially the T s -component to produce fissures mainly at the interface with the A - and G -component. The mixed acid reacted preferentially with the G - and T s -components, the Simons reagent reacting significantly only with the G -component. The mineral matter of metallurgical coke can act as a graphitization catalyst similar to nickel particles. Hence, the development of structural components within the metallurgical coke followed by gasification by carbon dioxide may cause weakening of the coke at the interfaces of components.

Factors governing the solubility of mesophase into pitch distillate

Abstract To explain the dissolution phenomena of mesophase into pitch distillate, the hydrogen donor ability of the distillate and the acceptor ability of the mesophase were examined using 1H n.m.r. The mixtures which consisted of 9,10-dihydroanthracene(9,10-DHA) and mesophase samples or organic compounds(9,10-DHA/mesophase or organic compound = 1/5wt/wt) were heated at 618K for 1 h in sealed glass tubing, and then measured by 1H n.m.r. The acceptor ability (Aa) of the mesophase was evaluated from the integrated intensity ratio between two peaks at 8.4 and 3.9 ppm, attributable to the resulting anthracene and the remaining 9,10-DHA, respectively. The solubility of a combination of mesophase and a distillate decreased with decreasing (Da + Aa) value, in which Da is the hydrogen donor ability of the distillate.

Thermal Stability of Magnetic Properties in Dehydrogenated Triarylmethane Resins

The stability of the magnetic properties of dehydrogenated triaryl-methane resins was investigated both at room temperature and at elevated temperatures. A magnetic property different from that reported in a previous paper was found in the course of studying the reproducibility of synthesis. This new property was examined through a mechanical response of the resins to a set of permanent magnets.