SBS改性沥青的阶段性老化特征与机理

Characteristics and Mechanism of SBS Modified Asphalt’s Phased Aging

摘要:

采用荧光显微镜、红外光谱和凝胶色谱等微观试验，分析苯乙烯丁二烯苯乙烯嵌段共聚物（SBS）改性沥青老化过程中的微观相态结构、沥青相的吸氧程度及分子尺寸构成的变化情况.试验与分析结果表明，SBS改性沥青存在着2个明显的老化阶段：第1阶段，沥青吸氧速率较低、小分子比例基本不变，SBS颗粒尺寸逐渐减小并最终发生凝聚、离析，导致SBS改性沥青的韧性逐渐下降，直至完全丧失；第2阶段，沥青吸氧速率显著增大、小分子比例减少，由于SBS降解后苯乙烯仍起到改性作用，使沥青稠度增大，从而沥青软化点呈上升趋势.

关键词:苯乙烯丁二烯苯乙烯嵌段共聚物(SBS)改性沥青; 老化过程; 阶段性机理; 微观分析

Abstract:

Microscopic tests, e.g. fluorescence microscopy, infrared spectroscopy and gel chromatography were used to analyze the changes of micro phase structure, oxygen inhalation level of asphalt phase and molecular size makeup during aging phase of styrenebutadienestyrene block copolymers(SBS) modified asphalt. Test and analysis results show that the aging of the SBS modified asphalt has two distinct aging phases. In the first aging phase, the oxygen inhalation rate of asphalt was low; the proportion of small molecules almost remains the same; the SBS particles gradually decrease in size and eventually agglomerate and segregate. In this phase, the toughness of the SBS modified asphalt gradually reduces until complete loss. In the second aging phase, the oxygen inhalation rate of asphalt significantly increases and the proportion of small molecules reduces. In this phase, as styrene still plays the role of modification after SBS’s degradation, asphalt’s consistency increases while its softening point tends to rise.

Key words:styrenebutadienestyrene block copolymers(SBS) modified asphalt; aging process; stage characteristics; macro analysis