Thermal analysis in foundry technology

Abstract

In this study, a polymer composition of poly(acrylic acid) and dextrin (PAA/D) cross-linked with microwave radiation, belonging to the new BioCo group of environmentally friendly foundry binders, was subjected to thermal analysis (TG–DTG–DSC, TG–MS, TG–IR) in a temperature range of 20–600 °C. A thermal analysis of PAA/D compositions enables the determination of a temperature range at which the composition is not susceptible to thermal degradation and thus does not lose its binding properties. The study showed that the process of thermal degradation of PAA/D is complex and multi-stage (TG–DTG–DSC). Within a temperature range of 20–250 °C, physical and chemical changes take place associated with the evaporation of the water fraction of the solvent (20–100 °C), next with the evaporation of the water hydration and finally with intermolecular dehydration reactions (100–250 °C). Above a temperature of 300 °C, the decomposition of the polymer chains takes places, and thereafter, the intensive degradation of PAA/D occurs together the creation of gaseous substances, primarily low molecular weight inorganic (CO2, H2O, CO) and organic compounds, including methane (TG–IR, TG–MS).