Crystallization Behavior of Isotactic Polyp ropylene/β-Nucleati ng Agent under Controlled Pressurization Conditions
β-Nucleating agents can not only provide a large number of nucleation sites for β-iPP crystallization and accelerate its crystallization,but also regulate the crystal morphology of iPP,which in turn affects its macroscopic properties.In this study,the crystallization behavior of isotactic polypropylene/β-nucleating agent(iPP/TMB-5)under different pressurization conditions was investigated using wide-angle X-ray diffraction and polarized optical microscopy.The results show that changing the pressurization conditions can not only control the self-assembly structure of TMB-5 and change the crystalline morphology of iPP,but also prepare iPP/TMB-5 products with different crystalline phases.At different pressurization temperatures,TMB-5 can self-assemble into needle-like,flower-like or dot-like structures,which in turn induces iPP to produce rod-like,flower-like or dot-like crystals;at lower pressurization pressures,TMB-5 can be assembled into larger-sized and better-structured aggregates,and the higher the pressure,the more detrimental to the self-assembly of TMB-5;at lower pressurization pressures(100,200 MPa),the higher pressurization rates can inhibit the self-assembly of TMB-5,and at lower pressurization pressures(100,200 MPa),the higher pressurization rates can inhibit the self-assembly of TMB-5.When the pressurization pressure is 500 MPa and above,this inhibitory effect is not obvious;in the process of iPP/TMB-5 high-pressure crystallization,there is a competitive growth phenomenon of β-iPP and γ-iPP,and the lower the pressurization pressure,the more favorable the formation of β-iPP,and vice versa for the generation of γ-iPP,and the higher the pressure is 500 MPa,the β-iPP completely disappears,and the β-iPP is prepared.iPP completely disappeared at a pressure of 500 MPa or higher,and pure γ-iPP/TMB-5 samples were prepared.
万方数据
维普
