气相二氧化硅的异氰酸酯改性及其对浇注型聚氨酯弹性体力学性能的影响

为了改善气相二氧化硅(FS)/浇注型聚氨酯(PU)体系成型流动性，在制备预聚体的过程中，采用2, 4-甲苯二异氰酸酯(TDI)进行改性获得异氰酸酯改性的二氧化硅(NCO@FS)，通过原位聚合法制备了NCO@FS/PU弹性体复合材料。采用FTIR、XPS及动态接触角对NCO@FS及FS进行了表征。结果表明：FS的表面羟基与TDI的-NCO基团发生反应生成了氨酯基(-NHCOO)，改善了FS与PU间的界面相容性及界面结合。复合材料中NCO@FS质量分数为1.5wt%时，NCO@FS/PU复合材料的拉伸和撕裂强度分别为57 MPa和110.5 kN/m，比纯浇注型PU分别提高了31.6%和23.6%；玻璃化转变温度由3.4℃下降到-11.2℃，损耗因子tanδ由0.59下降到0.46。异氰酸酯改性FS适合制备FS增强浇注型聚氨酯复合材料。

Isocyanate modified fumed silica and its effects on the mechanical properties of casting polyurethane elastomer

In order to improve the molding fluidity of fumed silica (FS)/cast polyurethane (PU) system, in the process of preparing prepolymer, the fumed silica (FS) was modified by 2, 4-toluene diisocyanate (TDI) to obtain TDI modified silica (NCO@FS), and TDI modified silica/reinforced pouring polyurethane (NCO@FS/PU) elastomer composite material was prepared by in-situ polymerization. NCO@FS and FS were characterized by fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle testing. The results show that the active hydroxyl groups on the surface of FS react with the —NCO groups of TDI to form urethane groups aminoester group (—NHCOO), which improves the interfacial compatibility and interfacial bonding between silica and casting polyurethane. When the mass fraction of NCO@FS in the composite material is 1.5wt%, the tensile and tearing strengths of the NCO@FS/PU composite material are 57 MPa and 110.5 kN/m, respectively, which are 31.6% and 23.6% higher than that of pure casting PU. The glass transition temperature dropped from 3.4°C to –11.2°C, and the loss factor tanδ dropped from 0.59 to 0.46. TDI modified fumed silica is suitable for preparing silica-reinforced cast polyurethane composites.