An idealized DSC thermogram for a hypothetical crystallizable polymer is depicted in Figure 6.2, which illustrates the types of transitions of interest to polymer chemists. The glass transition causes an endothermic shift in the initial baseline because of the sample’s increased heat capacity. Endothermic transition lie below the baseline in the thermogram, and the exothermic transition lie above, although this varies with the manufacturer of the device. In reporting transition temperatures, it is important to indicate whether one is referring to the onset of the transition or to the inflection point or peak maximum, as shown in Figure 6.3.