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In this study, four types of widely used commercial β-nucleating agents (β-NAs) were used to prepare β-nucleated isotactic polypropylene (β-iPP). Differential scanning calorimetry (DSC), polarizing optical microscopy (PLOM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were used to comparatively study the roles of β-NA in the β-nucleation efficiency, isothermal crystallization kinetics and crystalline morphology of the samples. Results revealed that the geometric shapes and thermal stabilities of the β-NAs are quite different from each other, moreover, the β-nucleation efficiencies (β-NE) of the β-NAs are quite different. The β-NE of NAB83 and PACA are very high, while those of TMB-5 and WBG‑II are relatively low. The critical concentrations of the β-NAs were obtained as follows: NAB83 = 0.02 wt %, PACA = 0.02 wt %, TMB-5 = 0.15 wt %, WBG = 0.3 wt %. Morphological studies of SEM and PLOM indicated that for different β-NAs, the β-phase fraction, crystalline sizes and morphology of the formed β-phase are quite different. Isothermal crystallization kinetics provided detailed kinetic information on the different β-NAs. [ABSTRACT FROM AUTHOR]