Fundamentals of apparatuses and analyses of DSC and TMA were described for polymeric materials. In apparatuses, measuring principles were explained firstly and secondly the two confusing problems of DSC, i.e., why two types of DSC, heat-flux DSC and power-compensation DSC, do still exist, and why their charts adopt opposite direction for Y-axis were elucidated from their historical and measuring aspects. In analyses, enthalpy and volume-temperature relationships of low molecular weight substance were reviewed and apparently unusual behaviors of polymers were pointed out. Finally nanosize behavior of polymer crystals was emphasized as the most important topic among them and their zero-entropy-production melting was exemplified for nylon 6 fibers, comparing with their conventional melting.