Analysis of the isothermal and nonisothermal transitions of hexagonal crystal formation from the melt (transition 1) and of monoclinic crystal formation from hexagonal crystals (transition 2) for trans-1,4-polybutadiene (TPBD) was carefully carried out by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Isothermal transitions I and 2 are described by Avrami exponents (n) of approximate to1, whereas nonisothermal transitions I and 2 are described by n approximate to 4. These different eta values indicate that different crystallization mechanisms took place for different crystallization driving forces under isothermal and nonisothermal crystallization. The Ozawa equation was also used to analyze the nonisothermal crystallization data. For transition I at lower temperature, the Ozawa equation fits the data well; however, at higher temperature, there is an inflection that shifts to lower crystallinity with increasing temperature. Inflections are also observed with the Ozawa analysis for transition 2. Furthermore, the crystallinities at the turning points are almost in the same range as those determined by Avrami analysis for nonisothermal transitions I and 2, which suggests that the Ozawa analysis inflections are due to secondary crystallization. However, TEM revealed no morphology discrepancy between the TPBD hexagonal crystals formed from melt by isothermal and nonisothermal crystallization. The agreement in activation energy (DeltaE) values determined by the Arrhenius and Kissinger methods indicates that the Avrami equation can describe the initial stage of transitions I and 2 in the nonisothermal transition process quite well. The DeltaE values determined by the Arrhenius and Kissinger methods for transition 1 are 167.4 and 179.2 KJ/mol, respectively, and those for transition 2 are 186.1 and 196.3 KJ/mol; respectively. (C) 2003 Wiley Periodicals, Inc.