Figure 11.19
TMA expansion study of an epoxy printed circuit board
showing the determination of the glass point (Tg).Dynamic Mechanical Analysis
An associated technique which links thermal properties with mechanical ones is dynamic mechanical
analysis (DMA). In this, a bar of the sample is typically fixed into a frame by clamping at both ends. It
is then oscillated by means of a ceramic shaft applied at the centre. The resonant frequency and the
mechanical damping exhibited by the sample are sensitive measurements of the mechanical properties
of a polymer which can be made over a wide range of temperatures. The effects of compositional
changes and methods of preparation can be directly assessed. DMA is assuming a position of major
importance in the study of the physico-chemical properties of polymers and composites.
11.5—
Pyrolysis-gas Chromatography
Summary
Principles
Controlled pyrolysis of small samples followed by GC separation of the products. Identification by MS
or FT-IR.