Analysis of the structure of bitumen-polymer composites based on IR spectroscopy data

Background: The use of bitumen-polymer composites is a relevant and promising approach to improving the performance characteristics of bituminous materials in road construction. Studying the structure and interaction mechanisms of components in such composites enables the optimization of formulations and enhancement of the final product’s quality. Aim: The aim of this research is to investigate the structure and the nature of interactions between the components of bitumen-polymer composites based on bitumen, polypropylene, and heavy petroleum residues using infrared (IR) spectroscopy. Materials and methods: The IR spectroscopy method was used to analyze structural changes in the composites. The spectra of the initial components (bitumen, polypropylene, heavy petroleum residues) and the modified bitumen were studied. A comparative analysis of the position and intensity of characteristic absorption bands corresponding to the main functional groups was carried out. Results: It was found that the introduction of polypropylene causes changes in the bitumen absorption spectra, particularly in the region of the stretching vibrations of carbon-hydrogen and carbon-oxygen bonds. This indicates structural transformations and redistribution of molecular interactions within the system. The additional incorporation of heavy petroleum residues amplifies these effects, resulting in changes in the physical properties of the composite, – notably, increasing the softening temperature and decreasing penetration. It was shown that the degree of interaction between components depends on polymer concentration and modification conditions. Conclusion: The obtained results reveal the mechanisms of structure formation and component interaction in bitumen-polymer composites, providing a scientific foundation for optimizing modified bitumen formulations. The work contributes to the development of research methodologies and expands the application of bituminous materials in construction and road industries.