聚氨酯改性沥青改性机理和性能

为了解决聚合物改性沥青储存稳定性差、易离析、易老化等问题, 利用聚氨酯(PU) 对沥青进行化学改性; 制备了PU改性沥青, 采用傅里叶变换红外光谱(FTIR)、动态热机械分析(DMA) 和差示扫描量热法(DSC) 试验研究了PU改性沥青的改性机理, 采用Brookfield旋转黏度试验、动态剪切流变(DSR) 试验、低温弯曲梁流变(BBR) 试验、旋转薄膜烘箱加热试验(RTFOT) 和紫外老化试验等评价了PU改性沥青、SBS改性沥青和70#基质沥青的性能。研究结果表明: 圆盘锯齿式搅拌器可以很好地暴露沥青中的活性基团, 使PU达到较好的改性效果; PU改性沥青中主要存在2种反应, 一是异氰酸酯与多元醇之间反应生成氨基甲酸酯, 二是异氰酸酯与沥青质中的芳香族化合物之间发生加成反应; PU改性沥青的高温布氏黏度高于同温度下的SBS改性沥青, 且64℃时的抗车辙因子是SBS改性沥青的6倍左右, 说明其高温性能非常优异; PU改性沥青RTFOT前后针入度比达到了85%, 软化点变化幅度为0.5℃, 说明其抗热氧老化性能非常优异; 在紫外老化试验中, PU改性沥青软化点和针入度变化范围分别为1℃~4℃和0.1~0.3 mm, 说明其抗紫外老化性能非常优异。 

Modification mechanism and performance of polyurethane modified asphalt

To solve the problems such as poor storage stability, easy segregation and aging for polymer modified asphalt, the polyurethane (PU) was used to chemically modify the asphalt. The PU modified asphalt was prepared. The Fourier transform infrared spectroscopy (FTIR) test, dynamic thermomechanical analysis (DMA) test and differential scanning calorimetry (DSC) test were conducted to analyze the modification mechanism of PU modified asphalt. The performances of PU modified asphalt, SBS modified asphalt and 70# base asphalt were evaluated by the Brookfield rotary viscosity test, dynamic shear rheological (DSR) test, low-temperature bending beam rheological (BBR) test, rotating thin film oven test (RTFOT), and ultraviolet aging test. Research result shows that the disk sawtooth agitator can expose the active group well in the asphalt, and make the PU achieve better modification effect. There are mainly two reactions in the PU modified asphalt. One is the reaction between the isocyanate and polyol to form carbamate, the other is the addition reaction between the isocyanate and aromatic compounds in the asphalt. The high-temperature Brookfield viscosity of PU modified asphalt is higher than that of SBS modified asphalt at the same temperature. The rutting factor of PU modified asphalt at 64 ℃ is about 6 times of that of SBS modified asphalt, showing that its high-temperature performance is excellent. The penetration ratio of PU modified asphalt before to after RTFOT reaches 85%. The softening point change scope of PU modified asphalt is 0.5 ℃, showing that its thermal oxygen aging resistance is excellent. In the ultraviolet aging test, the change scopes of softening point and penetration of PU modified asphalt are 1 ℃-4 ℃ and 0.1-0.3 mm, respectively, indicating that its ultraviolet aging resistance is excellent.