Simon R. Gibbon

Insights into Epoxy Network Nanostructural Heterogeneity Using AFM-IR

The first direct observation of a chemically heterogeneous nanostructure within an epoxy resin is reported. Epoxy resins comprise the matrix component of many high performance composites, coatings and adhesives, yet the molecular network structure that underpins the performance of these industrially essential materials is not well understood. Internal nodular morphologies have repeatedly been reported for epoxy resins analyzed using SEM or AFM, yet the origin of these features remains a contentious subject, and epoxies are still commonly assumed to be chemically homogeneous. Uniquely, in this contribution we use the recently developed AFM-IR technique to eliminate previous differences in interpretation, and establish that nodule features correspond to heterogeneous network connectivity within an epoxy phenolic formulation.

Mapping water uptake in organic coatings using AFM-IR

The long-term failure of seemingly intact corrosion resistant organic coatings is thought to occur via the development of ionic transport channels, which spontaneously evolve from hydrophilic regions on immersion, i.e., as a result of localized water uptake. To this end, we investigate water uptake characteristics for industrial epoxy-phenolic can coatings after immersion in deionized water and drying. Moisture sorption and the changing nature of polymer-water interactions are assessed using FTIR for dry and pre-soaked films. More water is found to be absorbed by the pre-soaked coatings on exposure to a humid environment, with a greater degree of hydrogen-bonding between the polymer and water. Furthermore, morphological changes are then correlated to localized water uptake using the AFM-IR technique. Nanoscale softened regions develop on soaking, and these are found to absorb a greater proportion of water from a humid environment.

Time-lapse lab-based x-ray nano-CT study of corrosion damage

An experimental protocol (workflow) has been developed for time‐lapse x‐ray nanotomography (nano‐CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano‐CT with the use of a combination of x‐ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time. For the pigmented polymer coating containing nominally strontium aluminium polyphosphate, the strontium‐rich components within the materials are observed to leach extensively whereas the aluminium‐rich components are more resistant to dissolution. In the case of AA2099 it is found that the initial grain boundary corrosion is driven by the presence of copper‐rich phases and is then followed by the corrosion of grains of specific orientation.

Corrosion control: general discussion.

[Cook, Angus; Davenport, Alison] Univ Birmingham, Birmingham B15 2TT, W Midlands, England. [Frankel, Gerald] Ohio State Univ, Columbus, OH 43210 USA. [Hughes, Trevor] Schlumberger Gould Res, Cambridge, England. [Gibbon, Simon] AkzoNobel RDI Marcus, Philippe] CNRS Chim ParisTech, Paris, France. [Lyth, Stephen] Kyushu Univ, Fukuoka 812, Japan. [Shoesmith, David; Wren, Clara] Western Univ, London, ON, Canada. [Wharton, Julian] Univ Southampton, Southampton SO9 5NH, Hants, England. [Hunt, Gregory] Lubrizol, Wickliffe, OH USA. [Lyon, Stuart; Lindsay, Rob; Morsch, Suzanne] Univ Manchester, Manchester M13 9PL, Lancs, England. [Majchrowski, Tom] Natl Nucl Lab, Workington, Cumbria, England. [Williams, Geraint] Swansea Univ, Swansea, W Glam, Wales. [Oller, Beatriz Rico; Nixon, Sonja] Airbus Grp Innovat, Ottobrunn, Germany. [Todorova, Mira] Max Planck Inst Eisenforsch GmbH, Dusseldorf, Germany. [Cheng, Su-Ting] Max Planck Inst Iron Res, Dusseldorf, Germany. [Scully, John] Univ Virginia, Charlottesville, VA 22903 USA. [Wilson, Ann] Univ W Indies, St Augustine, Trinid & Tobago. [Renner, Frank] Hasselt Univ, Inst Mat Res IMO, B-3590 Diepenbeek, Belgium. [Taylor, Christopher] DNV GL, Katy, TX USA. [Taylor, Christopher] Ohio State Univ, Columbus, OH 43210 USA. [Habazaki, Hiroki] Hokkaido Univ, Sapporo, Hokkaido 060, Japan. [Michaelides, Angelos] UCL, London, England. [Visser, Peter] Delft Univ Technol, NL-2600 AA Delft, Netherlands. [Kyhl, Line] Aarhus Univ, DK-8000 Aarhus C, Denmark. [Kokalj, Anton] Jozef Stefan Inst, Ljubljana, Slovenia.