Understanding your DMA - Answers to the Study Questions in DMA 3rd Ed.

When the third edition of our book, Dynamic Mechanical Analysis, was originally planned, our editor asked us to add study questions to the book. With his retirement followed by the whole COVID mess, we never developed an answer key. So we are going take the next couple of months to answer the questions here. This week we will start on the questions in chapter two. If you’d like to play:

1) On the curve in Figure 2.7a, mark the region of interest and explain what is happening there and why we would want to know.

2) Given a choice between nominal and true stress data, explain the pros and cons of each.  Why would you expect the true strain curve to deviate from the ideal at some point?

3) If we run a polymer in the DMA across several frequencies, we see the curve spread out into separate lines. Explain what is going on in terms of flow.

4) A material shows very different stress-strain curves when run at sub-ambient and room temperature. Explain the most likely cause.

5) When measuring flow, a wide range of different methods are used. What information would you expect to learn for an emulsion by spinning disk, capillary, and a dynamic frequency scan?

Figure 2.7a follows