Many polymers are semi-crystalline material. The percentage of crystallinity depends on many factors including chemical structure, interaction between polymer chains and processing conditions. One typical example is High Density Polyethylene (HDPE), a highly crystalline engineering thermoplastic. Historically, the glass transition for a highly crystalline material like HDPE could not be determined by Differential Scanning Calorimetry (DSC) since the step change in the heat flow signal as the material is heated through its glass transition cannot be observed at traditional scanning rates. In this study, an HDPE sample is used to demonstrate the increased sensitivity and ability to detect weak glass transitions with HyperDSC® using the PerkinElmer® DSC 8500.