Effect of Oleic Acid-modified Nano-CaCO3 on the Crystallization Behavior and Mechanical Properties of Polypropylene

Oleic acid OA-modified CaCO3 nanoparticles were prepared using surface modification method. In- frared spectroscopy IR was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene PP was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystal- lization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the for- mation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PPCaCO3 nanocompo- sites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical proper- ties of PP. In comparison with PP, the impact strength of PPCaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.