Thermal behavior of coal-tar pitch modified with BMI resin

Coal-tar pitch was modified with a bismaleimide (BMI) resin. Rheological properties and carbonization behavior of the pitch–BMI resin composites and optical texture of resultant semi-cokes were studied in this paper. The carbonization behavior was studied by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy techniques. In addition, the optical texture of resultant semi-cokes was characterized by polarized-light microscopy. Results show that the BMI resin content has great effect on the viscosity of the pitch–BMI resin composites. When the BMI resin content is 40 wt.%, the rheological behavior of the pitch–BMI resin composite is similar to that of a thermosetting resin with a U-type curve. Moreover, the pitch–BMI resin composites have better thermal stability than coal-tar pitch. The addition of BMI resin results in an increase in carbonization yield by 6.5% when the BMI resin content is 40 wt.% of the pitch–BMI resin composite. Also, the BMI resin has great effect on formation of the optical textures. When the BMI resin content is 10 wt.% of the pitch–BMI resin composite, the addition of BMI resin clearly improves the development of anisotropy on carbonization and the optical texture is flow domain anisotropy. Furthermore, there are higher aromaticity and more condensed polynuclear structures in resultant semi-cokes with increasing heat treatment temperature.