Research on the influence of fly ash-based hydrated salt doping on mine-used polyurethane

Abstract

Given the possible safety risks associated with polyurethane (PU) sealing materials frequently used in underground coal mines, this study conducted material modification utilizing a mix of experiments and simulations in the context of sustainable development and the reuse of industrial by-products. In previous studies, it was found that the best effect was achieved when 16 wt%MgSO₄·7H₂O + 12 wt% Na₂CO₃·10H₂O were incorporated into PU. Based on this, this paper continued incorporating 10 wt% - 60 wt% solid waste fly ash into the composite PU system for research. Firstly, the modification effect was explored and the optimal doping ratio was determined by measuring the curing temperature and using molecular dynamics simulations to simulate the glass transition temperature, diffusion coefficient, and so on. Secondly, the interaction energy, mechanical properties, specific heat capacity, free volume fraction, and other parameters of three major systems, namely pure PU, the system with the optimal doping ratio of hydrated salts, and the system with the optimal doping ratio of fly ash-based hydrated salts, were simulated and calculated to verify their usability. The results showed that when the doping ratio of fly ash was 50 wt%, the heat release during the curing of the PU material decreased by 21.90 %, the glass transition temperature increased by 30.66 %, the diffusion coefficient decreased by 97.14 % and the parameters of mechanical properties, specific heat capacity, and other properties all increased. This work lowered the temperature of the PU synthesis reaction, enhanced the material's performance and stability, decreased its cost, encouraged the use of PU, gave an example of how to use industrial byproducts, and supported sustainable development.