TGA and DMA studies of blends from very good coking Zofiówka coal and various carbon additives: Weakly coking coals, industrial coke and carbonized plants

Abstract

The aim of this work is to study the effects of various carbon additives, blended with very good coking coal, on the thermal decomposition of the blends. The blends possess fixed content (50 wt.%) of very good coking coal from the Zofiówka Mine. The remaining components of the blends are worse coking coals collected from the Janina, Krupiński, Szczygłowice, Jas-Mos mines (coals of carbon content ranging from 73 up to 92 wt.%), and very porous carbons: coke (from the coking plant Zdzieszowice), as well as woody stems of bamboo and yucca carbonized at 400 °C. The content of porous carbon in a blend does not exceed 20 wt.%. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) are used in the study. The weight loss during low-temperature pyrolysis (< 600 °C), and storage/loss elastic moduli measured as a function of the increasing temperature are related to the kind and concentration of additives. The temperature dependences of elastic moduli determined for binary coal blends differ clearly from those of ternary coal blends. The consumption of energy during the interaction of the components in binary blends was found to be distinctly bigger than the one observed for ternary blends. Non-softening additives such as carbonized plants and low rank coal, containing many functional groups, diminish both moduli of the blends distinctly. However, the addition of coke does not reduce the value of the elastic moduli but increases the width of the maximum occurring in the temperature dependence of the moduli. The influence of the coke additive on rheological properties of the blends, different in comparison with the remaining additives studied, was assigned with different number of functional groups and radicals.