Non-isothermal ultra-fast cooling crystallization tests were conducted on three blown film grade bimodal high density polyethylene (HDPE) resins using a fast differential scanning calorimeter, the Flash DSC. Non-isothermal tests were performed at cooling rates between 50 and 4000 degrees K/s, and the data were analyzed using the modified Avrami model by Jeziorny (Polymer, 1978, 19, 1142). Non-isothermal data were used to propose a new method named crystallization-time-temperature-superposition, and the two activation energies were obtained for each of the resins. This is very useful for obtaining theoretical crystallization kinetics data at different cooling rates, allowing its use in ultra-fast cooling polymer processes such as blown film. (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 1822-1827