The hierarchical structure of bitumen of different aging states at the molecular level and nanoscale

• Published in: Fuel (Guildford) Vol. 319; p. 123791
• Main Authors: Li, Fangjin, Wang, Yuhong, Zhao, Kecheng
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.07.2022; Elsevier BV
• Subjects: Aging; Aspect ratio; Asphaltene; Bitumen; Bitumens; Evaluation; GPC; Hierarchical structure; Image analysis; Image processing; Liquid chromatography; Microscopic level; Microstructure; Molecular structure; Pore size; STEM; Structural hierarchy; Asphaltene; Microscopic level; GPC; Bitumen; Hierarchical structure; STEM
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.123791

[Display omitted] •Realistic distributions of microstructures and molecules in bitumen are characterized.•Methods for proper characterizing bitumen using GPC are developed.•Evolutions of microstructures and molecular size of bitumen in aging are identified.•Connections between the hierarchical structure of bitumen and its properties are established. The realistic structure of bitumen at the microscopic level, although of great value to researchers and practitioners, has not been thoroughly and quantitatively examined. This study characterized twelve bitumen samples of various origins and aging states by fraction analysis, scanning transmission electron microscope (STEM), and gel permeation chromatography (GPC). Microstructures greater than 10 nm in STEM images were evaluated by their coverage areas, the longest dimensions, and aspect ratios. Microstructures and molecules of bitumen solutions that pass the filter of a pore size of 0.2 μm and the filter of a pore size of 0.45 μm were evaluated by the overall distributions of GPC chromatograms and the proportions in different size ranges. Combined information from fraction analysis, STEM image analysis, and GPC results reveals the realistic distributions of microstructures and molecules in bitumen at the molecular level and nanoscale. The effects of compositional and structural changes of bitumen on viscosities of the bitumen and its maltene phase were also evaluated.