聚合物改性沥青微细观相态结构的流变学响应特征

Rheological response characteristics of polymer modified asphalt microstructure

采用荧光显微镜研究不同SBS(苯乙烯—丁二烯—苯乙烯三嵌段共聚物)改性沥青的微观相态,测定不同相态结构SBS改性沥青的黏弹参数并构建流变函数曲线,深入分析流变曲线变化和相态结构间的关系。结果表明:随SBS质量分数从3%增加到7%,改性沥青的微观相态呈现3种相态转变,即SBS相为分散相演变为SBS/沥青双连续相,再到沥青为分散相的相态;SBS改性沥青的储存模量依频曲线可以较好地反映3种微观相态结构,储存模量依频曲线出现“平台区”且曲线低频区斜率α>2,则说明SBS相为分散相,曲线低频区为幂率特征且斜率α≤1,则说明SBS微观上形成网络结构;储存模量的依温曲线也可区分SBS改性沥青的微观相态,而流变曲线Han图和框图(black diagrams)对3种微观相态没有明显响应特征。

The microscopic phase states of different SBS modified asphalts were studied by fluorescence microscopy. Then, the viscoelastic parameters of SBS modified asphalts with different phase structures were determined and rheological curves were constructed. Lastly, the relationship between the changes of rheological curves and phase structures was deeply analyzed. It is found that the microscopic phase of SBS modified bitumen shows three phase transitions with the increase of SBS from 3% to 7%. In other words, SBS as dispersed phase evolves to SBS/asphalt bi-continuous phase and then to asphalt as dispersed phase. The dependence curves of storage modulus with frequency for SBS modified asphalt can better reflect the three microscopic phase structures. “Platform area” and the curve slope in low-frequency area α>2 means that the SBS phase is dispersed. The low frequency region of the curve is characterized by power rate and slope α ≤1, which indicates that SBS microscopically forms a network structure. The temperature dependence curves of storage modulus can also distinguish the three microscopic phase states, while the Han plot and Black diagrams have no obvious response characteristics for the three microscopic phase states.