I'm currently working through past exam papers in preparation for my upcoming Inorganic Chemistry exam and I got to this question. We really haven't looked at DSC graphs, so I'm not completely sure how to answer this. I've shown my attempt, but am looking for someone to confirm if I'm right, if not, where I went wrong.
Question: The DSC thermogram depicted below was run on a sample of a new compound suspected of possessing mesogenic properties. The thermogram was obtained at a scan rate of 10 °C min−1 and the solid line represents the heating scan, while the dashed line represents the cooling scan.
Interpret the DSC thermogram, naming and explaining the processes occurring at peaks (a) – (e), using the correct terminology. Does the DSC thermogram confirm that the new compound is a mesogen? If so, what can you say about the liquid crystal phase(s), and what name is given to this class of mesogen? What word describes this particular kind of thermal behaviour?
My answer: e = Crystallization, a = melting point (crystalline -> smectic), b = transition point (smectic -> nematic), d = (re)crystallization (nematic -> crystalline), c = melting point (crystalline -> nematic). Since a nematic phase is a subset of liquid crystal (synonym for mesogens), it confirms that the new compound is a mesogen. Molecules in the nematic phase are (somewhat) orientationally ordered (in contrast to the smectic phase which is (somewhat) orientationally and positionally ordered). I don't have an answer to "What word describes this particular kind of thermal behaviour?".