Resistance of Polymer-Bitumen Binders to Thermal Degradation

To study the thermal stability of bitumen binders, the method of synchronous thermal analysis using thermogravimetric analysis and differential scanning calorimetry was used in this work. To determine the thermoactive and thermodynamic properties (intervals of endothermic and exothermic effects, mass losses corresponding to these intervals, maxima of effects), bitumen and their modification products were studied by thermogravimetry (TG-DTG) and differential scanning calorimetry (DSC) on a microcalorimeter STA449-F3 (NETZSCH, Germany). The test samples (14.0-28.2 mg) were heated from room temperature to 800°C. The results of thermogravimetric analysis and differential scanning calorimetry of BND 70/100 bitumen and polymer-bitumen binders based on it are presented. The obtained thermal analyses indicate that all samples are characterized by two stages of thermal destruction, accompanied by endothermic effects, the thermal parameters of which allowed us to assess phase-structural changes. The effect of a styrene-butadiene-styrene (SBS) block copolymer on the processes of thermal degradation of polymer-bitumen binders is investigated. It was revealed that the most noticeable structural changes of bitumen binders are achieved with the introduction of SBS in the amount of 4% by weight. Thus, studies of the thermal behavior of polymer-bitumen binders have made it possible to identify processes occurring under thermal influence with structural and phase transformations. Temperature intervals of thermal transformations were determined for the studied objects, which allowed us to assess the phase-structural changes. It is revealed that the most noticeable structural changes of bitumen binders are achieved with the introduction of SBS. Synchronous thermal analysis is a very informative method of studying the thermal stability of bitumen binders, due to which it is widely used not only in fundamental disciplines - chemistry and physics, but also in oil refining, as well as in the road construction industry.