Thesis for the degree of the Candidate of Technical Sciences (PhD) on specialty 05.17.07 – Chemical Technology of Fuels and Lubricants (161 chemical technologies). Donetsk National Technical University, specialized academic council D 08.084.05 at the National Metallurgical Academy of Ukraine, Dnipro, 2018.
This study considers the results of theoretical and experimental studies of basic stabilization of the modified coal tar pitch as a basis for pitch-composite by using stabilizing additives to prevent thermal and oxidation degradation of the material, as well as determining the resistance of the resulting pitch-composite to the effect of liquid aggressive media.
The influence of individual stabilizers (irganox, melamine, calcium stearate, and zinc stearate) on the thermal and oxidation degradation of the initial and modified coal tar pitch (MCTP) was studied. It was established that the selected stabilizers interact with the pitch, but their influence in most cases leads to an intensification of the process of thermal and oxidation degradation, and only melamine always slows down the processes of destruction and reduces the mass loss of the material.
The study considered the effect of the mixture of irganox-melamine (IM) antioxidants on MCTP and determined a synergistic effect, which slows down the processes of degradation and reduces mass loss (up to 40%). Thermogravimetric analysis showed that a mixture of IM antioxidants can reduce or completely block the decomposition of PVC with the formation of hydrocarbon radicals, which initiate the degradation of MCTP. Based on IR spectral analysis, it has been established that antioxidants reduce the degree of aromaticity and condensation of the system, and methylene bridges and ester bonds appear.
The effect of the complex IMSS stabilizer (Irganox-Melamine-calcium stearate-zinc stearate) on the degradation of the modified coal tar pitch was studied for the first time. The obtained scientific and experimental results allowed to develop the composition of complex IMSS stabilizer, which slows down the processes of degradation of MCTP as part of pitch-composite under the conditions of its preparation, as well as determine the possibility of using the material in various aggressive environments.
The study involves the development of process flow diagram and recommendations for basic stabilization of pitch-composite based on the modified coal tar pitch. In the course of industrial research at NPO Tekhnodon LLC, the prototypes of pitch-composite based on the MCTP were obtained at the research and industrial plant and the stabilizing effect of the complex IMSS stabilizer, which preserves the rheological properties of the material, was experimentally proved. These results will allow using modified coal tar pitch as the basis for the production of composite materials. The research results are accepted for industrial production of a pitch-composite based on MCTP.
The research results obtained in the thesis are used in the educational process at the Department of Chemical Technologies of the Donetsk National Technical University in the execution of thesis works and in teaching such disciplines as Fundamentals of the Technology of Solid Fuels Processing, Modern Technologies of Combustible Minerals Processing to the students of specialty 161 “Chemical Technologies and Engineering”.
Keywords: coal tar pitch, modification, polyvinyl chloride, degradation, stabilization, stabilizing additives, composite materials, pitch-composite.
