Crystallization behavior and application properties of PP modified by organic phosphate nucleating agents compounded with different metal ions
It is an effective and feasible way to control the crystallization behavior of polypropylene(PP)by adding nucleating agents to improve its application performance of polymers.PP-Li or PP-Na composites with 0.5%AlP/LiSt mass fraction or 0.5%AlP/NaSt mass fraction were prepared by melt blending method.PP-Li or PP-Na composites with 0.5%AlP/LiSt mass fraction or 0.5%AlP/NaSt mass fraction were prepared by melt blending.The crystallization behavior of PP composites was analyzed by differ-ential scanning calorimeter and polarizing microscope,the experimental results show that AlP/LiSt and AlP/NaSt nucleating agents,as effective nucleation sites,can significantly increase the crystallization temperature of PP and refine PP spherulites.At a cooling rate of 5℃/min,the crystallization temperatures of PP-Li and PP-Na composites are increased to 127.7℃and 131.3℃respective-ly,compared with the crystallization temperature 113.5℃of pure PP.The mechanical property results show that the tensile strength of PP-Li and PP-Na composites are 6.7%and 14.8%higher than that of pure PP,while the flexural modulus are 16.6%and 38.0%higher than that of pure PP,respectively.It indicates that AlP/LiSt and AlP/NaSt nucleating agents can greatly improve the tensile strengths and flexural modulus of PP.The impact strength of PP-Na composites is basically the same as that of pure PP,and the impact strength of PP-Li composites is still 10.3%higher than that of pure PP,indicating the improvement effect of AlP/NaSt nucle-ating agent is better than that of AlP/LiSt.AlP/LiSt nucleating agent is superior to improve the toughness of PP.The activation energy data of thermal degradation reaction(Ed)of PP composites calculated by Kissinger method show that both nucleating agents are beneficial to improve the heat resistance of PP.The Ed values of PP-Li and PP-Na composites are 55.4 kJ/mol and 49.3 kJ/mol higher than that of pure PP,which reflecte that the temperature and energy required for thermal degradation of PP-Li and PP-Na composites are higher than that of pure PP.
phosphate salt nucleating agentcrystallization propertyheat resistance propertypolypropylenemechani-cal property
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