Bonding Mechanism Between Waterglass/Polyurethane Adhesive and Coal

Chemical grouting in underground coal mines is related closely to the interaction between grouting materials and coal. In the present work, a novel adhesive with high properties and low cost, waterglass/polyurethane, has been developed for coal bonding, based on a room-temperature-curing process. To obtain a direct and comprehensive understanding of the adhesive interaction at the surface of coal, quartz crystal microbalance (QCM) and Fourier-transform infrared spectroscopy (FTIR) techniques were employed to investigate the bonding process of waterglass/polyurethane adhesive on coal coating. The obtained information suggests that the interaction between the NCO groups in pMDI and the OH groups at the surface of coal is the dominant bonding force. The mechanical tests indicate that the compressive and flexural strength of the coal/adhesive composition can reach 21.4 and 5.8 MPa, respectively.