Effect Of Zinc Phenylphosphonate And Multiamide On Crystallization Behavior Of Isotactic Polypropylene

In this thesis, the effect of zinc phenylphosphonate (PPZn) andN,N’,N’’-tricyclohexyl-1,3,5-benzenetricarboxylamide (defined as TMC in this thesis)on the crystallization of isotactic polypropylene (iPP) were investigated bydifferential scanning calorimetry (DSC), polarized optical microscopy (POM) andwide angle X-ray diffraction (WAXD). The results of this thesis in detail are asfollows:(1) The effect PPZn as an efficient nucleating agent on the crystallizationbehavior of iPP was investigated for the first time in this thesis. PPZn-nucleated iPPwas prepared via melt-blending method. The nonisothermal and isothermalcrystallization of iPP/PPZn composites were studied by DSC. PPZn shows excellentnucleating effect on iPP. The nucleation efficiency (NE) of the composites reaches32%even at very low loading of0.02wt%PPZn. With further increasing the contentof PPZn, the value of NE increases gradually and reaches50%at1wt%of PPZn. For0.1wt%PPZn, the crystallization half-time of the composite decreases from19.42to1.87min at134oC, compared with pure iPP. The isothermal crystallization data werefurther analyzed by the Avrami model. The values of the Avrami exponent of thecomposites are comparable to that of pure iPP, indicating that the presence of PPZndoes not change the crystallization mechanism of the matrix. The presence of PPZnincreases significantly the nuclei density and crystallization rate of iPP but has nodiscernible effect on its crystalline structure, evidenced by POM and WAXDmeasurements.(2) The effect of TMC on the crystallization behavior of iPP was studied in thisthesis. TMC-nucleated iPP was prepared via melt-blending method. Thenonisothermal and isothermal crystallization of iPP/TMC blends were investigated byDSC. TMC shows excellent nucleating effect on iPP. The nucleation efficiency of theblends reaches30%even at very low loading of0.05wt%TMC. With furtherincreasing the content of TMC, the value of NE increases gradually and reaches52%at1wt%of TMC. For0.1wt%TMC, the crystallization half-time of the blend decreases from39.41to3.97min at136oC, compared with pure iPP. The isothermalcrystallization data were further analyzed by the Avrami model. The values of theAvrami exponent of the blends are comparable to that of pure iPP, indicating that thepresence of TMC does not change the crystallization mechanism of the matrix. Thepresence of TMC increases significantly the nuclei density and crystallization rate ofiPP but has no discernible effect on its crystalline structure, evidenced by POM andWAXD measurements.