基于黏弹力学的SBS改性沥青改性剂网络结构研究

摘要

In order to investigate the reaction time on cross-linking process of modifier in SBS modified asphalt,based on the share stress versus time curve observed by shear test,the network intensity,a new concept used as an index was introduced to evaluate the network structure of modifier.The results,combined with the softening point test were used to study the relationship of network structure with performance at high temperature and storage stability.The network structure of the modifier forms through two stages:partial crosslinking and entire crosslinking.The partial crosslinking is a reversible process in a metastable state and only has limited effect on the improvement of storage stability and softening point.While the stability of entire crosslinking structure is much better and is a key factor to improve softening point.The changes of the softening point present a trend as the reaction time of the modifier with asphalt prolongs:first reduction and then elevation.This trend is resulted from both the modifier morphology and structure changes.%为探讨发育时间对SBS改性沥青改性剂网络结构的影响,通过剪切试验分别得到不同发育时间样品的剪切应力曲线,提出网络结构评价指标——网络强度.对各样品的交联情况进行评价,结合软化点试验探索网络结构与高温性能、储存稳定性的关系.结果表明:改性剂网络结构的形成经历了局部交联、整体交联阶段;局部交联是可逆反应,所形成的结构处于亚稳定状态,对软化点及储存稳定性的提升作用有限;整体交联结构较为稳定,是软化点得到改善并维持的关键因素,随着发育的进行,软化点呈现先降低后升高的趋势,这种趋势是由改性剂形态变化与结构变化两个因素共同作用的结果.