The Research On Low Heat Storage Of Modified PU Composite Grouting Material

Polyurethane grouting materials are widely applied in coal mine,construction and other fields because of its mechanical properties and specific capability in corrosion resistance. During the curing, it will produce a lot of heat inside,which will cause a danger of fire when meeting the materials of low ignition point. Therefore it is of great significance to reduce the highest heat storage temperature in the course of application. In order to improve the heat storage capability of Polyurethane grouting materials, the dissertation will focus on reducing the system heat release and improving the system thermal conductivity respectively. The main contents are the three lists in the following:(1) By using 2-methyl-4-ethyl imidazole ring opening epoxy resin grafted polyurethane, the EP/PU of interpenetrating polymer networks grouting material were prepared. The ring-opening reaction of epoxy resin and properties of modified polyurethane grouting materials were analyized by using HNMR、FT-IR、Mechanics Performance Testing、SEM、TGA and the corresponding characteristic of heat storage performance testing. The results show that:when using 2-methyl-4-ethyl imidazole and epoxy resin to prepare the hydroxyl epoxy resin, the rate of ring opening is about 10%. When the amount of -NCO vs -OH is 4, and the supplementary volume is 30%, the tensile strength of polyurethane grouting materials is 74.3MPa, adhesive property is 104Mpa. Microstructures imply the tensile section is a ductile fracture. The TGA results show that when the supplementary volume of EP is 30%, the los-mass rate of the material is only 58% at the temperature of 448℃,the thermostability is improved and the highest heat storage temperature dropped to 105℃.(2) Through using the socyano of MDI to react with the amino on the surface of nano BN, Si3N4, the nanochains were prepared with the method of the Step-Growth Polymerization. The nanochains morphology were characterized by TEM to investigate the influence of the concentration,reaction temperature and the amount of MDI. The results show that it is efficient to control the polymerization to get soft nanochains when the concentration of nano nitride is lmg/mL,and reaction temperature is below 25℃, and the hydrophobic property also have a great improvement compared with the original sample.(3) The influences of BN、Si3N4 on modified polyurethane grouting materials were also investigated. The results show that nanochains can improve the mechanical properties,thermal conductivity,heat storage capability in a varying degrees. Nanochains can improve the materials thermal conductivity greatly with a lower supplementary volume compared with the original nanoparticles sample. When supplementary volume of the BN nanochains is 3%, the tensile strength of polyurethane grouting materials will reach the value as high as 71.2 Mpa, the highest value of adhesive property is 4.1Mpa. When supplementary volume of the BN Nanochains is 15%, the thermal conductivity of composite grouting materials is 0.7909w/m-k, and the highest heat storage temperature is dropped to 102℃, heat dissipation rate is 2.12℃/min. When supplementary volume of the Si3N4 nanochains is 15%, the thermal conductivity is 0.4243w/m·k with an improvement of 17.37%, and the highest heat storage temperature is 109℃, heat dissipation rate is 1.99℃/min. The thermal conductive network of nanochains in PU matrix is verified through the fixed Agari thermal transfer model.