Danylo I. Development of gas-filled carbon composites based on modified coal tar pitch

The results of theoretical and experimental studies of the process of producing carbon solid foams based on modified coal tar pitch using a complex blowing agent are defended, which will allow them to be used as heat-insulating materials. The dependence of the degree of the complex blowing agent (azodicarbonamide-zinc stearate) decomposition on the temperature in the range of 130 – 150 °C and the amount of zinc stearate initiator was established, which allows to determine the optimal blowing agent composition and temperature to achieve the maximum degree of decomposition. It was experimentally established that through a low-temperature modification of coal tar pitch with polyvinyl chloride (5 – 20 wt. part) and polymethyl methacrylate (1 – 5 wt. part) its viscosity increases because of the formation of high molecular condensed aromatic compounds, which is confirmed by IR spectroscopy and X-ray diffraction analysis. The kinetics of foaming at 150 °C of coal tar pitch modified with polyvinyl chloride and polymethyl methacrylate using a complex blowing agent in an amount of 1 – 3 wt. part (per 100 wt. part of modified coal tar pitch) was studied. The foam criterion depends on the amount of the complex blowing agent, polyvinyl chloride and polymethyl methacrylate and reaches from 2.5 to 3.6. Based on IR-spectral analysis, it has been established that the destruction of oxygen-containing functional groups and the removal of methyl groups occur during foaming of the modified pitch, are leading to an increase of the aromaticity of the solid carbon foams. The conducted studies have made it possible to obtain carbon solid foams with porosity up to 42 % and an apparent density from 0.76 g/cm3 based on modified coal tar pitch by foaming using a complex blowing agent at a pressure of 0.145 – 0.265 MPa. The study involves the development of process flow diagram and a temporary process instruction for foaming a modified coal tar pitch using a complex blowing agent to create the carbon foams. The research results obtained in the thesis are used at the Department of Chemical Technologies of Donetsk National Technical University in the execution of the bachelor's and master's works of the students of the specialty 161 "Chemical Technologies and Engineering". Keywords: Coal tar pitch, polyvinyl chloride, polymethyl methacrylate, modification, azodicarbonamide, zinc stearate, foaming, carbon foams.