Influence of Temperature on the Rheological Properties of Composite Suspensions Based on Pyrocarbon

Abstract

The disposal of used automobile tires is a significant environmental challenge. In industrialized countries, the average annual number of discarded tires per person is approximately one. One of the most common methods of tire recycling is pyrolysis. The solid residue of this process is pyrocarbon. Due to its high dispersity, the presence of numerous submicron carbon particles, and significantly greater porosity compared to coal, pyrocarbon is a promising additive for the production of composite slurry fuel. Such fuel systems are influenced by various external factors, particularly temperature, which alters their properties. It has been established that increasing the temperature from 10°C to 20°C leads to a sharp decrease in the effective viscosity of the medium. Further temperature increases result in a less pronounced reduction in viscosity. In the range of 40–50°C, a slight acceleration in the rate of change of rheological characteristics is observed in the studied composite suspensions. At shear stress levels up to 20 Pa, the viscosity of the suspension decreases sharply due to the intensive breakdown of structural bonds. At 30–60 Pa, the system behaves as a Newtonian fluid with constant viscosity, indicating complete destruction of the structural network. It has been shown that as the temperature rises from 20°C to 40°C, the degree of thixotropy increases, reflecting the system’s strong ability to recover through enhanced particle interactions. However, at 50°C, thermal degradation of spatial structures occurs. The established performance characteristics of the obtained suspensions make them suitable for use as liquid fuel in fuel-fired boilers.