Study on molecular mechanism of polyoxyethylene to prevent coal and rock and gas composite dynamic disasters

Coal-rock-gas composite dynamic disaster is one of the most serious disasters in deep coal mining. Many studies have shown that energy-absorbing materials can effectively prevent composite disasters, but the current research on this kind of materials is in the exploratory stage, and there are problems such as low economy, poor efficiency, and unclear microscopic mechanism. In this paper, the microcosmic potential of polyoxyethylene (PEO) to prevent and control coal-rock-gas composite dynamic disaster was investigated from the perspective of molecular simulation (MD). Firstly, the adsorption energy of CH₄-coal (C-C), PEO-coal (C-P), and CH₄-PEO-coal (C-P-C) cell systems, the mean square displacement (MSD), radial distribution function (RDF), the accessible surface area (CSA), and the relative concentration distributions of CH₄ in different components along the Z-axis were calculated and analyzed. The results show that PEO has a stronger adsorption capacity on the coal surface than CH₄, and the adsorption capacity of the C-P system after PEO adsorption on the coal surface is weaker than that of the raw coal system, which proves that PEO can form a competitive adsorption situation with CH₄ on the coal surface, effectively weaken the adsorption capacity of coal to CH₄ and isolate CH₄. The potential mechanism of PEO to isolate gas and prevent coal and gas outburst is revealed. Then, uniaxial compression simulations of the raw coal and the C-P systemin the Z-axis direction were carried out to clarify the microscopic mechanism of PEO to improve the mechanical properties of coal. The stress-strain curves of the two systems are divided into microscopic compaction stage, microscopic linear elasticity stage, microscopic yielding stage, microscopic strengthening stage, and microscopic full compaction stage. Secondly, the pore development of coal under different pressures (sliding, dislocation, crack increase, deformation, compactness, etc.) is obtained by inversion of CSA analysis results of the two systems. At the same time, in order to clarify the deformation and failure characteristics of coal under different pressures, the distribution of RDF curves of N atoms in the molecular structure of coal in different systems is calculated. The mechanical simulation results show that PEO can effectively improve the compressive properties of coal molecular structure after adsorption on coal surface, and can play a good energy absorption effect when used in mine line. Finally, the feasibility of using PEO as an energy-absorbing auxiliary material in the mine line is discussed, and the micro-mechanism of its action to prevent and control coal-rock-gas composite dynamic disaster is clarified. This study can provide some technical support and theoretical guidance for the development of energy-absorbing materials.