水玻璃改性聚氨酯灌浆材料制备与性能研究

Preparation and properties of polyurethane grouting materials modified by waterglass

针对聚氨酯灌浆材料在引调水隧洞不良地质体堵水加固处理中存在造价较高和力学强度较低等问题,采用水玻璃对聚氨酯材料改性,制备改性油溶性聚氨酯,研究多苯基多亚甲基多异氰酸酯(PAPI)、水玻璃和催化剂添加量对材料抗压强度的影响,通过扫描电镜(SEM)和傅里叶变换红外光谱(FI-IR)测试,研究改性聚氨酯的结构对性能的影响规律。结果表明:PAPI、水玻璃和催化剂添加量对试样强度影响大小顺序为水玻璃>催化剂>PAPI;当m(PAPI)∶m(水玻璃)∶m(催化剂)=20∶20∶1时,纯固化体抗压强度达到49.5 MPa,结石体抗压强度达到16.5 MPa,优于其他同类产品。进一步微观分析结果表明:改性后的聚氨酯材料表面均匀,无明显微裂纹,各部分连接为较好的整体;随着水玻璃用量的增加,波数在1050 cm^(-1)附近的红外特征吸收峰逐渐增强,聚合物链段中引入了无机Si—O键,该结构提高了聚氨酯的抗压强度。采用水玻璃改性制备的聚氨酯降低了使用成本,提高了材料力学强度,有望在引调水工程隧洞破碎围岩堵水加固处理中推广应用。

During the construction of the headrace tunnel,water inrush and rock instability often occur when facing unfavorable geological bodies,causing project delays and equipment damage.Grouting has been used as a traditional and effective solution to water blocking and reinforcement to effectively avoid the occurrence of accidents.The grouting material is one of the important factors influencing the grouting effect.To realize the high-performance grouting treatment,a variety of grouting materials such as cement,ultrafine cement,sol-gel,waterglass,epoxy resin,polyurethane,and acrylate have been developed.Among grouting materials,polyurethane has been attracting tremendous attention in terms of its extraordinary properties.More specifically,the isocyanate group(—NCO)in polyurethane reacts with water rapidly,the secondary filling ability for micro-fractures due to carbon dioxide exerted from the reaction between—NCO and water,which is especially suitable for the treatment of water inrush.However,there are some drawbacks of polyurethane such as expensive and low compressive strength,which limits its practical applications.Given the problems such as high cost and low compressive strength of polyurethane grouting materials when it is used in water blocking and reinforcement of unfavorable geological bodies,the composite strategy is an important consideration in the performance improvement of grouting materials,such as PU/cement,and epoxy/cement.Some previous studies have shown that polyurethane/waterglass is an organic-inorganic hybrid material that integrates the advantages of both polyurethane and waterglass but avoid their drawbacks.To date,the highly efficient consolidation of polyurethane and waterglass grouting materials has been achieved.Oil-soluble polyurethane was modified by waterglass and the modified polyurethane was prepared successfully.However,the content of raw materials such as polyphenyl polymethylene polyisocyanate(PAPI),waterglass,and catalyst has an impact on the compressive strength of the modified polyurethane.Therefore,to explore the influence of the content of PAPI,waterglass,and catalyst on the compressive strength of materials,the orthogonal experiment design was used to analyze the influence of different PAPI,waterglass,and catalyst content on the compressive strength of the modified polyurethane,and the significant factors affecting the compressive strength were determined.The structures and properties of the materials were characterized by scanning electron microscope(SEM)and Fourier transform infrared spectroscopy(FT-IR)to understand the influence of microstructure on macro strength.Results showed that the strength of materials was most affected by the content of waterglass,less by the catalyst,and least by the PAPI.When m(PAPI):m(waterglass):m(catalyst)=20∶20∶1,the strength of the curing body and stone body reached 49.5 and 16.5 MPa,respectively,which is superior to other similar products.Further microstructure analysis demonstrated that the surface of the modified polyurethane was uniform without obvious fine crevices,and the phases in grouting materials were interconnected with each other.The characteristic absorption peak near 1050 cm^(-1) gradually increased with the increase of waterglass content,indicating that—NCO reacted with the activated silanol generated from the hydrolysis of waterglass.Inorganic Si—O bond was introduced into the polymer chain segment and formed a stable inorganic-organic interpenetrating network structure,which further improved the compressive strength of the material.In this research,polyurethane was modified by cheap waterglass.This not only reduce the cost but also improve the compressive strength of materials,which is expected to expand the application scale of polyurethane in the water plugging and reinforcement engineering of broken surrounding rock during the construction of the headrace tunnel.