Modulated Thermomechanical Analysis – Measuring Expansion and Contraction at the Same Time

摘要

In modulated thermal analysis, a sinusoidally varying temperature program is added to anrnunderlying linearly changing or static temperature program. Fourier transformation of thernoscillatory temperature "forcing function" and the result dependent variable provides therndeconvolution of these signals into reversing and nonreversing components. The reversingrnsignal is associated with properties dependent upon the temperature rate of change while thernnonreversing signal defines kinetic events (that is, those associated with both time andrntemperature). Thus for modulated thermomechanical analysis (MTMA?), coefficient of thermalrnexpansion is observed in the reversing signal and stress relaxation, softening and heat shrinkingrnare observed in the nonreversing signal. The ability of MTMA to measure both expansion andrncontraction simultaneously is demonstrated on samples including thermoset composite printedrncircuit boards and heat-shrink packaging film.