Theory and application of dynamic mechanical thermal analysis

Abstract

The dynamic mechanical technique of applying a sinusoidally oscillating stress to a material and the analysis of the resultant strain is now widely practised. The basic theory underlying this method is discussed and the application of dynamic mechanical analysis (DMTA) to a wide range of materials ranging from solid composites through to polymer melts is considered. Data may be collected under computer control in the temperature plane; in the frequency plane at a set of preselected temperatures; or isothermally as a function of time. Thus, the dynamic mechanical technique has been applied to a wide variety of different systems. Examples which are considered in this paper include; The study of polymer blends and phase morphology; The effect of orientation on the mechanical properties of solid polymers; The deviation of master curves using the time-temperature superposition principle; Investigation of the cure properties of thermosetting resins and fibre reinforced composites and finally, the study of melting semi-crystalline polymers. This list of applications is by no means exhaustive but will serve to illustrate the flexibility of this method for materials characterisation.