From Polymer Reference Book
Two techniques, dynamic mechanical thermal analysis (DMTA) and dielectric thermal analysis (DETA), have been used for the study of resin cure. Differential scanning calorimetry (DSC) has also been employed (for a discussion of the theory and instrumentation of DSC, see Chapter 9). The application of differential photocalorimetry to the measurement of cure rates of photocurable resins is discussed in Chapter 12.
10.1 Dynamic Mechanical Thermal Analysis
10.1.1 Theory
Although DMTA has found its major applications in the mechanical testing of plastics (see Chapter 15), it has also found application in degradation studies, chemical reaction studies such as resin curing measurements (i.e., degree and rate of cure), and studies of temperature properties of elastomers.
In resin cure studies the technique characterises the rheological changes in resins before, during, and after cure. Plots of temperature versus permittivity pinpoint the glass transition temperature (T g) for the resin during cure. Plots of time versus logarithm of loss factor enable determinations of vitrification of resins during cure to be carried out.
The rheological changes in a polymer during complex thermal histories can provide information about polymer processing, chemical structure, and end-use performance (time or temperature versus logarithm of loss factor, time versus logarithm of conductivity, and temperature permittivity plots).
10.1.2 Instrumentation
Some available instrumentation and software for DMTA is listed next (see also Appendix 1):
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Perkin Elmer: Series 7, Model DMA-7
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DuPont: 9000 Thermal Analysis System, Model 983
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PL Thermal Sciences: Model PL DMA
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TA Instruments: Model DMA 983
10.1.3 Applications
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