Abstract: Nucleators SLG1 and SLG2 were prepared from TEOS, stearic acid, and calcium phthalate. The thermal stability of SLG1 and SLG2 was studied with thermogravimetry(TG). Their nucleation behavior in polypropylene was studied with X-ray diffraction, polarized optical microscopy, and differential scanning caloimetry. The showed both SLG1 and SLG2 induced polypropylene to crystallize into β form. The crystallization temperature and crystallization rate were increased, but degree of crystallinity was decreased. Upon adding the nucleators, the spherulites became smaller with interface blurred. While the addition of SLG1 and SLG2 were 0.15 % and 0.3 %, the impact strength of PP was increased from 9.43 kJ/m2 to 21.82 kJ/m2 and 37.79 kJ/m2, respectively, while the tensile strength decreased slightly.

Key words: polypropylene, β-crystal form, nucleating agent, crystal morphology