微波对胶粉与沥青交互作用的影响

INFLUENCE OF MICROWAVE ON INTERACTION BETWEEN CRUMB RUBBER AND ASPHALT

制备了不同微波时间处理的胶粉改性沥青,用凝胶渗透色谱测定了微波处理胶粉的甲苯抽出物的相对分子质量分布,采用溶剂抽提法将胶粉改性沥青的胶粉相与沥青相分离,用热重分析考察胶粉的交联度和橡胶烃含量的变化。结果表明,胶粉改性沥青的性质与其在甲苯中的溶解度有明显的联系;经过5min微波处理的胶粉,在沥青中的降解程度最高,胶粉在沥青中破碎形成带状结构,其制备的改性沥青的延度和针入度最高,软化点稍低;微波处理时间为5min时胶粉中的部分大分子发生解交联,产生中等大小的分子,而继续延长微波处理时间到6min,使5min时形成的中等分子又重新与大分子反应连接。沥青中胶粉的交联度随微波时间延长先减小后增加,4min时达到最小,而橡胶烃含量随微波时间延长先减小后增加,5min时达到最小。胶粉交联度的减小有利于沥青中轻组分溶胀进入胶粉内部,使沥青中重组分相对含量提高,沥青变硬。而胶粉中降解产生的小分子,进入沥青后,使沥青变软,并且在胶粉和沥青之间形成界面层增强了二者的作用力。

Modified asphalts by crumb rubber powder with different microwave treating time were prepared. The molecular weight distribution of toluene extract of the crumb rubber microwave treated was determined by gel permeation chromatography. The crumb rubber and asphalt in modified asphalt were separated by solvent extraction to further investigate the crosslinking degree of the crumb powder and rubber hydrocarbon content changes using TG﹣DTA. Results show that the property of the modified asphalt has significant relations with its solubility in toluene. The crumb powder treated with microwave 5 min has the highest degree of degradation in asphalt,and forms banded structures. The crosslinking of part of the macromolecular are decomposed,producing medium﹣sized molecules. The modified asphalt by crumb powder treated 5 min has the highest ductility and penetration but slightly lower in softening point. However,if the microwave treatment time prolongs to 6 min,the crosslinking of the medium﹣sized molecules formed at 5 min treatment occurs again. It is discovered that the extent of crossliking of powder in modified asphalt first decreases and then increases as the microwave treating time prolongs, the lowest crosslinking appears at 4 min treatment. While the rubber hydrocarbon content presents a trend of first decrease and then increase,with 5 min treatment,the content is down to the lowest. De﹣creasing the crosslinking is advantageous for the light components in asphalt swelling into the powder inside,raising the heavier components content,and thus helpful to harden the modified asphalt. The small molecules produced by degradation can enter into and soften the asphalt and form an interface layer between powder and asphalt that enhances the interaction of them.