The Influence of HHPA Metal Salts on the Properties and Crystallization Behavior of Isotactic Polypropylene

摘要

Metal salts of HHPA as nucleating agents for isotactic polypropylene (iPP) have been synthesized. The influence of the nucleating agents on the optical properties, mechanical properties of iPP was tested and the results show that the Calcium HHPA is the most effective in enhancing the clarity of iPP and the best additive dosage obtained is 1.5%.The crystallization kinetics of iPP and nucleated PP with HHPA salts were investigated by the differential scanning calorimeter (DSC) under isothermal condition. It is found that the Avrami exponent becomes smaller and the t1/2 decreases dramatically, indicating the crystallization of the nucleated iPP with Calcium HHPA is mainly via heterogeneous nucleation.It can be seen clearly through polarized light microscopy (POM) that the density of nuclei of iPP nucleated by Calcium HHPA increases with the decrease of the spherulite size.