不同嵌段共聚物对改性沥青微观形态及高温性能影响

Effects of different styrenic triblock copolymers on micromorphology and high temperature performance of modified asphalt

为探究不同种类苯乙烯系三嵌段共聚物(styrenic triblock copolymer,STC)对改性沥青粒径分布、相容性及高温性能的影响,分析粒径特征参数与相容性的相关性,首先进行荧光显微试验观测改性剂在改性沥青中的微观形态,并使用专业图像分析软件(image pro plus,IPP)计算荧光颗粒特征参数判断分散均匀性;其次对改性沥青进行频率扫描并绘出Han曲线,由低频区的斜率表征STC与沥青相容性,并分析Han曲线斜率与荧光颗粒特征参数相关性;最后对改性沥青进行温度扫描、频率扫描、多重压力蠕变恢复试验(MSCR)测试不同种类STC对改性沥青高温流变性能影响。研究结果表明:根据STC种类特征可以看出,嵌段比及结晶程度越大的改性剂更难在改性沥青中分散均匀,但含有甲基侧链能提升改性剂在沥青中的分散均匀性,星形结构的改性剂分散均匀性弱于线形结构;荧光显微图的荧光颗粒特征参数与Han曲线斜率有良好的相关性,其中平均粒径及粒径极差的相关性最好,可依据荧光颗粒这2个特征参数初步判断改性剂与沥青的相容性;嵌段比为3/7的苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性沥青抗车辙性能、零剪切黏度(zero shear viscosity,ZSV)值及弹性恢复性能最佳,高温流变性能最好;星形结构改性沥青能形成强度更高的网状结构,高温流变性能优于线形结构;氢化苯乙烯-丁二烯嵌段共聚物(SEBS)的高结晶程度使改性沥青复合模量、ZSV值更大,但其较小的熵弹性使改性沥青弹性恢复性能降低;苯乙烯-异戊二烯-苯乙烯(SIS)因侧链的活化程度高,与沥青质产生相互作用力,使改性沥青弹性恢复性能优异,同时也因为侧链降低了结晶度,使其复合模量更低。

In order to explore the effects of different types of styrenic-based triblock copolymers(STC)on the particle size distribution,compatibility,and high temperature performance of modified asphalt,and to analyze the correlation between particle size characteristic parameters and compatibility,first,fluorescence microscopy experiments were conducted to observe the microstructure of the modifier in the modified asphalt,and image pro plus was used to calculate the fluorescence particle characteristic parameters to determine the dispersion uniformity.Secondly,frequency sweep tests were conducted on the modified asphalt and Han curves were drawn.The slope of the low frequency region characterized the compatibility of STC with asphalt,and the correlation between the slope of the Han curve and the fluorescence particle characteristic parameters was analyzed.Finally,temperature sweep tests,frequency sweep tests,and MSCR tests were performed on the modified asphalt to investigate the effects of different types of STC on the high temperature rheological properties of modified asphalt.The results show that according to the characteristics of STC,it is more difficult for the modifiers with larger block ratio and crystallization degree to disperse evenly in the modified asphalt,but containing methyl side chains improves the dispersion uniformity of the modifiers in the asphalt.The dispersion uniformity of the modifiers with a star structure is weaker than that of the linear structure.The characteristic parameters of fluorescent particles in fluorescence micrograph have a good correlation with the slope of the Han curve,and the correlation between average particle size and particle size range is the best.The compatibility between the modifier and asphalt can be preliminarily judged based on the two characteristic parameters of fluorescent particles.Styrene butadiene styrene(SBS)modified asphalt with a block ratio of 3/7 has the best resistance to rutting,ZSV value,and elastic recovery performance,and the best high-temperature rheological properties.Star-shaped structure modified asphalt forms a stronger network structure and has better high-temperature rheological properties than the linear structure.The high crystallinity of styrene ethylene butylene styrene(SEBS)makes the composite modulus and zero shear viscosity(ZSV)of the modified asphalt larger,but its smaller entropy elasticity reduces the elastic recovery performance of the modified asphalt.Styrene isoprene styrene(SIS)has a high degree of side chain activation,which interacts with the asphalt to produce excellent elastic recovery performance of the modified asphalt.At the same time,due to the side chains,the crystallinity is lowered,resulting in a lower composite modulus.6 tabs,5 figs,36 refs.