https://arpi.unipi.it/bitstream/11568/798598/2/polacco%20798598.pdf

A review of the fundamentals of polymer-modified asphalts: Asphalt/polymer interactions and principles of compatibility

Summary Bitumen is a complex mixture of hydrocarbons for which microstructural knowledge is incomplete. In an effort to detail this microstructure, 13 bitumens were analysed by phase-detection atomic force microscopy. Based on morphology, the bitumens could be classified into three distinct groups. One group showed fine domains down to 0.1 microm, another showed domains of about 1 microm, and a third group showed up to four different domains or phases of different sizes and shapes. No correlation was found between the atomic force microscopy morphology and the composition based on asphaltenes, polar aromatics, naphthene aromatics and saturates. A high correlation was found between the area of the 'bee-like' structures and the vanadium and nickel content in bitumen, and between the atomic force microscopy groups and the average size of molecular planes made of fused aromatics. The morphology and the molecular arrangements in bitumen thus appear to be partly governed by the molecular planes and the polarity defined by metallic cations.

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Bitumen morphologies by phase-detection atomic force microscopy.

With the ever increasing demand for energy to meet the needs of growth in population and improvement in the living standards in particular in developing countries, the abundant unconventional oil reserves (about 70% of total world oil), such as heavy oil, oil/tar sands and shale oil, are playing an increasingly important role in securing global energy supply. Compared with the conventional reserves unconventional oil reserves are characterized by extremely high viscosity and density, combined with complex chemistry. As a result, petroleum production from unconventional oil reserves is much more difficult and costly with more serious environmental impacts. As a key underpinning science, understanding the interfacial phenomena involved in unconventional petroleum production, such as oil liberation from host rocks, oil–water emulsions and demulsification, is critical for developing novel processes to improve oil production while reducing GHG emission and other environmental impacts at a lower operating cost. In the past decade, significant efforts and advances have been made in applying the principles of interfacial sciences to better understand complex unconventional oil-systems, while many environmental and production challenges remain. In this critical review, the recent research findings and progress in the interfacial sciences related to unconventional petroleum production are critically reviewed. In particular, the chemistry of unconventional oils, liberation mechanisms of oil from host rocks and mechanisms of emulsion stability and destabilization in unconventional oil production systems are discussed in detail. This review also seeks to summarize the current state-of-the-art characterization techniques and brings forward the challenges and opportunities for future research in this important field of physical chemistry and petroleum.

Interfacial sciences in unconventional petroleum production: from fundamentals to applications

Asphalts used in the construction of pavements exhibit unique properties at the micron and nanometre scale. Atomic force microscopy (AFM) images of asphalts and asphalt chromatographic fractions prepared as thin films clearly show that a variety of ‘microstructures’ can develop on the surface of these types of materials. Structure develops to different degrees and in different forms depending on the residua crude source from which the asphalt or asphalt fraction is derived, the thermal history of the sample and the sample thickness. Based on our current best interpretation of a very large number of AFM images obtained over several years, we hypothesise that the interaction between crystallising paraffin waxes and the remaining asphalt fractions is responsible for much of the structuring, including the well-known bee structures (Loeber et al. 1996, Journal of Microscopy, 182 (1), 32–39), which has been observed with asphalt materials.

Morphology of asphalts, asphalt fractions and model wax-doped asphalts studied by atomic force microscopy

Improving the aging resistance of styrene-butadiene-styrene tri-block copolymer modified asphalt by addition of antioxidants

Bitumen in colloid science: a chemical, structural and rheological approach

AFM is an easy, nondestructive tool to study the structure of asphalt and the association and size of its individual particles. Best observation conditions were obtained with rigid cantilevers and a very smooth surface (drop form). In comparison to AFM, SEM needs an adequate preparation method to prevent artefacts by the deoiling step. This was obtained by using filter paper, which keeps the structure in place.

L. Loeber

Papers

Bitumen in colloid science: a chemical, structural and rheological approach

Atomic Force Microscopy—A New and Complementary Tool in Asphalt Research Compared to Scanning Electron Microscopy