基于^(1)H-NMR的老化对沥青分子结构的影响研究

Effect of Aging on the Molecular Structure of Asphalts Based on ^(1)H-NMR Spectroscopy

对不同原油生产的4种沥青(A1、A2、A3、A4)分别进行薄膜烘箱老化(TFOT)、紫外光老化(UV)和压力老化(PAV),利用核磁共振氢谱(;H-NMR)研究了老化对不同沥青分子结构的影响。结果表明:TFOT老化后,沥青分子发生了缩合脱氢,芳香环上支链减少,发生了烷基链环化,芳环增多,脂肪直链裂解为短链;PAV老化后,沥青进一步发生了芳构化和缩聚反应,同时短脂肪支链聚合形成长链;UV老化后,沥青缩合程度不断增加,同时产生较多短支链。在4种沥青中,Har含量小,Hβ含量高的沥青(A1),芳香结构多,缩合程度高,老化后分子结构变化小;Har含量高,Hα含量高的沥青(A2),支链较多,缩合程度低,老化后分子结构变化大。

Four kinds of asphalts(A1,A2,A3 and A4)from different crude oils were treated with thin film oven aging(TFOT),pressure aging vessel(PAV)and ultraviolet aging(UV).The effects of aging on the molecular structure of different asphalts were investigated using nuclear magnetic resonance hydrogen spectroscopy(1 H-NMR).The results showed that the asphalt underwent condensation dehydrogenation,the branched chains on aromatic rings decreased,alkyl chain cyclization occurred,aromatic rings increased,and aliphatic branched chains cracked into short chains after TFOT aging.The asphalt underwent further aromatization and condensation reactions,and the short-branched chains were polymerized to form long chains after PAV aging.The condensation degree of asphalt increased and more short branched chains were produced after UV aging.Asphalt(A1)with low Harcontent and high Hβcontent has more aromatic structure,high degree of condensation,and the change of molecular structure was small after aging.The asphalt with high Har,high Hαcontent has more branched chains and low condensation degree,the molecular structure changed greatly.