Dynamic mechanical analysis (DMA) measures the viscoelastic properties of materials by applying a periodic stress in different deformation modes while varying temperature or frequency. In DMA, the sample is subjected to forces like bending, tension, shear or compression, and the modulus is measured as a function of time or temperature to provide information about phase transitions. DMA is useful for characterizing materials' mechanical properties and transitions, validating other analysis methods, and evaluating factors like polymer composition and miscibility.