Authors:D. Price, M. Reading, R. Smith, H. Pollock, and A. Hammiche
Micro-thermal analysis employs a scanning probe microscope fitted with a miniature resistive heater/thermometer to obtain
images of the surface of materials and then perform localised thermo analytical measurements. We have demonstrated that it
is possible to use the same configuration to pyrolyse selected areas of the specimen by rapidly heating the probe to 600–800°C.
This generates a plume of evolved gases which can be trapped using a sampling tube containing a suitable sorbent placed close
to the heated tip. Thermal desorption-gas chromatogaphy/mass spectrometry can then be used to separate and identify the evolved
gases. This capability extends the normal visualisation and characterisation by micro-thermal analysis to include the possibility
of localised chemical analysis of the sample (or a domain, feature or contaminant). The isolation and identification of natural
products from a plant leaf are given as an example to illustrate this approach. Preliminary results from direct sampling of
pyrolysis products by mass spectrometry are also presented.
Authors:D. Hourston, M. Song, H. Pollock, and A. Hammiche
Modulated-temperature differential scanning calorimetry was used to measure the glass transition temperature,Tg, the heat capacity relaxation in the glassy state and the increment of heat capacity, δCp, in the glass transition region for several polymers. The differential of heat capacity with respect to temperature was used
to analyseTg and δCp simply and accurately. These measurements are not affected by complex thermal histories.
Authors:D. Price, M. Reading, A. Hammiche, and H. Pollock
This paper describes recent advances in thermal analysis instrumentation which combine the high resolution imaging capabilities
of the atomic force microscope with physical characterisation by thermal analysis. Images of the surface may be obtained according
to the specimen's thermal conductivity and thermal expansivity differences in addition to the usual topographic relief. Localised
equivalents of modulated temperature differential scanning calorimetry, thermomechanical and dynamic mechanical analysis have
been developed with a spatial resolution of a few micrometres. A form of localised thermogravimetry-evolved gas analysis has
also been demonstrated. The same instrument configuration can be adapted to allow IR microspectrometry at a resolution better
than the optical diffraction limit.
Authors:M. Song, D. Hourston, M. Reading, H. Pollock, and A. Hammiche
A modulated-temperature differential scanning calorimetry (M-TDSC) method for the analysis of interphases in multi-component
polymer materials has been developed further. As examples, interphases in a polybutadiene-natural rubber (50:50 by mass) blend,
a poly(methyl methacrylate)-poly(vinyl acetate) (50:50 by mass) structured latex film, a polyepichlorohydrinpoly(vinyl acetate)
bilayer film, and polystyrene-polyurethane (40:60 by mass) and poly(ethyl methacrylate)-polyurethane (60:40 by mass) interpenetrating
polymer networks were investigated. The mass fraction of interphase and its composition can be calculated quantitatively.
These interphases do not exhibit clear separate glass transition temperatures, but occur continually between the glass transition
temperatures of the constituent polymers.
Authors:H. Gersch, J. Robertson, A. Henderson, D. Pollack, and C. Munson
Particle-induced X-ray emission (PIXE) spectrometry is being used to nondestructively determine the elemental composition
of copper-based artifacts excavated from prehistoric/protohistoric sites in the Ohio River Valley. Copper objects from Caborn-Welborn
(C-W) and contemporary Fort Ancient sites are being studied so as to differentiate between native American and European copper.
The trace element analysis of metal artifacts enables archaeologists to more accurately assess the material culture and chronological
development of C-W society (A.D. 1400–1700) with particular reference to geological sources of copper and brass.