the relationship between side chain isomerism of aliphatic C4 substituted 1,3,5-benzenetricarboxylamides (BTARs, 1,3,5-benzenetricarboxylic acid tris(tert-butylamide) (BTA-TB), 1,3,5-benzenetricarboxylic acid tris(iso-butylamide) (BTA-IB) and 1,3,5-benzenetricarboxylic acid tris(n-butylamide) (BTA-NB)) and nucleation effects in iPP were investigated by differential scanning calorimeter (DSC), polarizing optical microscope (POM) and wide-angle X-ray diffractometer (WXRD). The results showed BTA-TB, BTA-NB and BTA-IB were efficient nucleating agents for iPP, and all of them induced formation of alpha-form spherulites and increased the crystallization peak temperature of iPP dramatically. However, BTA-NB had dual nucleation abilities for both alpha- and beta-form crystals and induced iPP to form beta-form spherulites at high content. The, optimum contents of BTA-TB, BTA-NB and BTA-IB in iPP were 0.25 wt%, 0.3 wt% and 0.15 wt%, respectively. Under the optimum content the crystallization peak temperature of iPP nucleated with BTA-TB, BTA-NB and BTA-IB increased from 122.5 degrees C of neat iPP to 130.4 degrees C, 132.1 degrees C and 130.1 degrees C, respectively.