The Preparation And Property Of Hydrophilic Polyurethane Grouting Material For High Performance Applications

In this paper, high-performance hydrophilic polyurethane grouting material was synthesized through prepolymer method. The main research and experimental results were divided into three parts.The low toxicity polyurethane grouting material was prepared by MDI and polyether mixture. The effects of polyether functionality and molecular weight, catalyst, diluent contents, as well as R value, namely the ratio of -NCO and -OH were studied and the reaction process was optimized. The results showed that A33 is better than the triethanolamine in catalytic efficiency; with the increasing of R value, the viscosity of prepolymer and the gel time decreased while the water absorption capability raised. Viscosity of the material is decreased with diluent addition. When R value is fixed, with the increasing of low molecular weight portion in premixed polyether, the prepolymer water absorption capability was improved.The polyurethane prepolymer terminated with hydroxyl was obtained through the reaction of TDI and hydrophilic polyether mixture with different molecular weight. Than the prepolymer reacted with MDI to synthesis a high-performance hydrophilic polyurethane grouting material whose gel time can be adjusted. The results show that, with the increasing of low molecular weight portion in premixed polyether, the slurry viscosity reduced, the gel time, foaming capacity and water swelling ratio were all increased. With the increasing of TDI content in pre-polymer, the slurry viscosity decreased, the gel time prolonged while the water swelling ratio had few changes. With the increasing of MDI portion, the viscosity and gel time reduced, while foaming capacity and density were both increased; with the increasing of diluent, the density was increased and the viscosity was decreased, while the gel time increased in the beginning and then decreased. When R of the pre-polymer combined through TDI and polyether was 1.6, total R of the reaction system (R2) was 7 and the content of diluent was 30%, the hydrophilic polyurethane grouting material has the best properties:the density was 1.14g/mL, the viscosity was 702mPa·s, the gel time of slurry and water reaction was 30s, the water absorption capability was 47s, the foaming capacity of forming solid was 978% and water swelling ratio was 182%.The prepolymer of hydrophilic polyurethane is synthesized by diisocyanate and polyether polyol, and then the polyurethane prepolymer blends with sodium silicate solution to prepare nanosilica-reinforced hydrophilic polyurethane composites (HPU/nano-SiO2) via in-situ reactions. The FTIR-ATR and X-ray diffraction (XRD) are employed to confirm the existence of the nano-SiO2 and its chemical bond to HPU chain, and the size and dispersion of nano-SiO2 in HPU matrix are investigated by transmission electron microscopy (TEM). The gel time of the mixture consisting of HPU prepolymer and sodium silicate solutions and the mechanical properties of HPU/nano-SiO2 composites are also tested. The results show that the particles of nano-SiO2 disperse homogeneously in the HPU matrix, and the nano-SiO2 combines with HPU chains by chemical bonds to form HPU/nano-SiO2 composites. What's more, the gel time of HPU and sodium silicate solution blend increases compared to that of the blend of HPU and water, and the compression strength of HPU/nano-SiO2 is improved effectively than that of pristine HPU, so the HPU prepolymer can react with sodium silicate solutions to produce the nanosilica reinforced hydrophilic polyurethane grout.