Goaf sealing wall is set in the roadway close to the stop line of working face in an underground coal mine. However, the sealing wall is prone to crack or fracture under serious mining stress, resulting in water and air leakage from goaf. In this study, the combination of polymethylene polyphenyl polyisocyanate (PAPI) and methylene diphenyl diisocyanate (MDI) as component A and polyether polyols, catalysts, surfactants, chain extenders, and plasticizers as component B were investigated to optimize the exothermic, foaming, and mechanical properties of modified polyurethane (PU) as the filling material for goaf sealing wall. Firstly, the reaction temperature of specimens with different contents of polyether polyols was monitored using a dynamic acquisition system; secondly, the effect of polyether polyols, catalysts, and surfactants on foaming property was studied; then, uniaxial compression tests were developed to obtain compressive behavior; finally, the microstructure after uniaxial compression was observed by using a scanning electron microscope (SEM). The results indicate that the pure chemical slurry is superior to the combination of chemical slurry and sand in compressive strength and deformation behavior. The optimal mass ratio of polyether triols, polyether tetraols, catalysts, surfactants, chain extenders, and plasticizers is 11 : 9 : 1.0 : 0.5 : 1.2: 6 in component B due to the maximum reaction temperature of 121.4°C, the expansion ratio of 2.6, and the compressive strength of 7.97 MPa at the strain of 10% in this study. The research provides a solution for the construction of the sealing wall, which is of great significance to safety production in an underground coal mine.

中文翻译：

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改性聚氨酯作为采空区密封墙填充材料的放热，发泡和力学性能的优化

在地下煤矿中，靠近工作面停止线的巷道中设置了采空区密封墙。然而，在严重的采矿压力下，密封壁易于破裂或断裂，从而导致采空区漏水和漏气。在这项研究中，研究了将聚亚甲基多苯基多异氰酸酯（PAPI）和亚甲基二苯基二异氰酸酯（MDI）作为组分A和聚醚多元醇，催化剂，表面活性剂，扩链剂和增塑剂作为组分B的组合，以优化放热，发泡和机械性能。改性聚氨酯（PU）作为采空区密封墙填充材料的性能。首先，使用动态采集系统监测不同含量的聚醚多元醇样品的反应温度。其次，聚醚多元醇，催化剂的作用 研究了表面活性剂对发泡性能的影响；然后，进行单轴压缩试验以获得压缩性能。最后，使用扫描电子显微镜（SEM）观察单轴压缩后的显微组织。结果表明，纯化学浆液的抗压强度和变形性能优于化学浆液和砂的结合。组分B中聚醚三醇，聚醚四醇，催化剂，表面活性剂，扩链剂和增塑剂的最佳质量比为11：9：1.0：0.5：1.2：6，这是因为最高反应温度为121.4°C，在本研究中，应力为2.6，抗压强度为7.97 MPa（10％应变）。该研究为密封墙的施工提供了解决方案，