Preparation of a Novel Inorganic–Organic Nucleating Agent and Its Effect on the Foaming Behavior of Polypropylene

In this study, a supramolecular compound (Zn@Q[6]) was synthesized by cucurbit[6]uril (Q[6]) and zinc acetate [Zn(Ac) 2 ] through a chemical method. Powder X-ray diffraction and X-ray crystallography analyses were conducted to confirm the crystallographic structure of Zn@Q[6]. Results showed that the four-coordinated Zn(II) centre coordinated with four chloride ions, and each [ZnCl 4 ] 2− anion interacted with three Q[6] molecules through hydrogen bonds between Q[6] and the chloridion of [ZnCl 4 ] 2− . Subsequently, Zn@Q[6], Zn(Ac) 2 and the mixture of Zn(Ac) 2 and Q[6] were introduced respectively as nucleating agents into polypropylene (PP) microcellular injection using azodicarbonamide (ADC) as a chemical blowing agent. Compared with Zn(Ac) 2 and the mixture of Zn(Ac) 2 and Q[6], improved cell morphology was obtained with addition of Zn@Q[6] obviously at relatively high injection temperatures, except 175 °C, at which no obvious improvement in Zn@Q[6] was observed. The underlying mechanisms were then discussed by thermal and rheological analyses. Zn@Q[6] could be a novel inorganic–organic nucleating agent that can suppress the catalysis activity of Zn(II) for the decomposition of ADC and PP.