Hydrogenated Modification Of Coal-tar Pitch With Rosin For Carbon Materials

Coal-tar pitch was modified with rosin in this paper. We studied the relation amongmodification process, structure, properties and fractions of the modified pitches. Therheological behavior, thermal decomposition, coking behavior, and mesophasetransformation behavior of the modified pitches were studied.An overall study was made in the relation among modification process, properties andfractions of the modified pitches. The results show that modification process greatlyinfluences the properties and fractions of the modified pitches. The properties of themodified pitches are listed as follows: softening point is77.6~86.0℃, carbonization yieldis38.4~50.1%, and density is0.99~1.30g/cm3. In addition, the contents of TS, TI-PS, andPI of the modified pitches have good linearity relation with their carbonization yield,softening point and density.The permeability of the modified pitches was investigated. The results show that thepermeability of the modified pitches increases with increasing rosin content or temperature.The modified pitches show non-Newtonian fluid. The viscosity of the modified pitches,which have low viscous activation energy, decreases with increasing temperature.The thermal decomposition behaviors of the modified pitches were studied usingFourier transform infra-red (FT-IR), elemental analysis, X-ray diffraction (XRD) andthermogravimetric analysis (TGA). The results show that the modified pitches have higherC/H atomic ratio and more regular structure in resultant semi-cokes with increasing heattreatment temperature. The addition of the rosin changes the thermal decomposition ofcoal-tar pitch and thus deteriorates its thermal stability. Moreover, TG curves of themodified pitches were fitted successfully by the proposed kinetics model, which wellreveals the thermal decomposition behaviors of the modified pitches.The optical texture of resultant semi-cokes of the modified pitches was characterizedby reflected polarized-light microscopy. The results show that the addition of the rosin isbeneficial to improve the optical textures. When the BMI resin content is10wt.%ofcoal-tar pitch, the optical texture is domain anisotropy. In addition, the optical texture isimproved with increasing heat treatment temperature. The mesophase transformation behavior of the modified pitches was investigated inthis paper. The high mesophase yield can be obtained when the content is10wt.%ofcoal-tar pitch. The kinetics parameters of the mesophase transformation of the modifiedpitches are calculated, indicating that the modified pitch has high activation energy (Ea)and pre-exponential factor (A).