Suzanne Morsch

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.

Investigating the Photocatalytic Degradation of Oil Paint using ATR-IR and AFM-IR

As linseed oil has a longstanding and continuing history of use as a binder in artistic paints, developing an understanding of its degradation mechanism is critical to conservation efforts. At present, little can be done to detect the early stages of oil paint deterioration due to the complex chemical composition of degrading paints. In this work, we use advanced infrared analysis techniques to investigate the UV-induced deterioration of model linseed oil paints in detail. Subdiffraction limit infrared analysis (AFM-IR) is applied to identify and map accelerated degradation in the presence of two different grades of titanium white pigment particles (rutile or anatase TiO2). Differentiation between the degradation of these two formulations demonstrates the sensitivity of this approach. The identification of characteristic peaks and transient species residing at the paint surface allows infrared absorbance peaks related to degradation deeper in the film to be extricated from conventional ATR-FTIR spectra, potentially opening up a new approach to degradation monitoring.

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.

AFM-IR insights into the chemistry of interfacial tracking

Composite materials are increasingly used in high-voltage insulation, where interfacial aging is a major source of failure. Nonetheless, the mechanism underpinning polymeric degradation remains ill-defined. This is in part due to the highly localised and complex range of reactions induced by partial discharges. In this contribution, we first present a correlation between track propagation over time and the partial discharge magnitude in the region between a glassy epoxy amine resin and silicone rubber. We then use ATR-FTIR and the newly developed atomic force microscopy infrared (AFM-IR) technique to produce detailed nano-chemical maps of interfacial tracks and buried channels. Local infrared spectra reveal that oxidation of the epoxy resin, which has previously been associated with the formation of interfacial tracks and electrical trees when detected by conventional bulk FTIR, in fact occurs across the entire interface and is concentrated within the damaged channel regions. In contrast, for silicone rubber the bulk ATR-FTIR spectra remain essentially unchanged after electrical ageing, whereas local AFM-IR analysis reveals the development of Si–O–C bonds across the interface and C–O–C bonds within tracks.