棒状薄层色谱-氢火焰离子探测仪检测老化沥青的四组分

Determination of the four generic fractions of aged bitumen by thin-layer chromatography with flame ionization detection

沥青老化过程中四组分(饱和分、芳香分、胶质和沥青质)会发生变化,分析沥青在老化过程中四组分的变化有助于揭示沥青的老化机理,科学指导沥青材料的工程应用。分别采用薄膜烘箱试验(TFOT)、压力老化容器(PAV)试验和紫外光(UV)老化试验对沥青进行老化,利用棒状薄层色谱-氢火焰离子探测仪(TLC-FID)检测沥青老化前后的四组分,研究了扩展液组成对沥青四组分测定结果的影响,并与溶剂沉淀及色谱柱法(Corbett法)测定结果进行了对比。通过线性拟合分析了TLC-FID法与Corbett法检测老化沥青四组分的相关性。结果表明,采用二氯甲烷配制沥青溶液,以正庚烷为第一扩展液、甲苯/正庚烷(80∶20,v/v)为第二扩展液、甲苯/乙醇(55∶45,v/v)为第三扩展液,并利用TLC-FID方法检测老化沥青的四组分较为合适。该方法对于沥青四组分的分析及沥青老化机理的研究具有重要意义。

The aging process of bitumen has been paid more and more attention by the researchers. The four generic fractions （ saturates, aromatics, resins and asphaltenes） of bitu- men change significantly during the aging process. The analysis of the changes of the four generic fractions of bitumen is very helpful to reveal the bitumen aging mechanisms and guide its engineering applications. In this study, the bitumen was aged by thin film oven test （TFOT）, pressurized aging vessel （PAV） test and ultraviolet （UV） aging test, respectively. Then the four generic fractions of bitumen before and after aging were analyzed by thin-layer chromatography with flame ionization detection （TLC-FID）, which was further compared with the solubility procedures and chromatographic technique （named as Corbett method ）. The compositions of the expanded solvents were also investigated. Finally, the correlation between the TLC-FID and Corbett method was further studied, which revealed a proper TLC-FID meth- od for detection of aged bitumen. The bitumen solution dissolved by dichloromethane was suc- cessively expanded by n-heptane, toluene/n-heptane （ 80 ： 20, v/v） and toluene/ethanol （ 55 ： 45, v/v）, followed by TLC-FID. This method is of great significance for the analysis of the four generic fractions of bitumen and for the exploration of bitumen aging mechanisms.