Influence Of Special Nucleation Agent On Polypropylene Properties

The polypropylene(PP) is a thermo-plastic which has good properties, but its impact strength is low. As a result, the application of PP is limited in some areas. Good impact properties ofβcrystalline PP widens the application of PP. At present, the introduction ofβ-nucleating agent is a recognized reliable method to prepareβcrystalline PP. In this paper, TMB-5β-nucleating agent was added to PP during melt processing. The experimental results revel that the impact strength of PP was increased with increasing the amount ofβ-nucleating agent, and reached a max value at 0.3%β-nucleating agent, then decreased. The maximum impact strength ofβ-PP is four times higher than that of pure PP. The tensile and flexural strength were first decreased and then increased with increasing the amount ofβ-nucleating agents. The influence ofβ-nucleating agent on non-isothermal crystallization kinetics was characterized by means of DSC, and the crystallization rate of PP was increased by addingβ-nucleating agent. With the addition of nucleation agent, the wear resistance of PP increased, and some crystalline of PP was transferred from a type toβtype.According to the theory of inorganic oxides used as polymer nucleation agent, the different amount of ZrO₂ was used as polypropylene nucleation agent to improve its properties. The nonisothermal crystallization kinetics of PP/ZrO₂ was investigated by using Differential Scanning Calorimetry (DSC). The modified Avrami theories and Jeziorny method were used to analyze the date of DSC, respectively. The experiment results reveal that the active energy of crystallization of PP decreased with the addition of ZrO₂. The crystallization and morphology of polypropylene were investigated by using differential scanning calorimeter (DSC) and X—ray diffractometer. The spherulite sizes were studied by polarizing microscope. With the addition of ZrO₂, the tensile strength of PP decreased but impact strength and elongation at break increased. The impact strength reached 13.7 kJ/m² when the amount of ZrO₂ is 0.3%. The spherulite sizes of PP crystalline decreases by adding ZrO₂. ZrCb not only acts nucleating agent in PP, but also makes some crystalline of PP transfer from a type toβtype.