Preparation, thermal and mechanical properties of zinc Sulphide/Polypropylene composites

Abstract

Zinc sulfide pigments are the most important inorganic white, apart from titanium dioxide and zinc oxide pigments. Here, we proposed the combined method of hydrothermal synthesis, calcination and sand milling to prepare zinc sulphide nanoparticles (ZnS NPs). ZnS NPs were mainly prepared by the precipitation reaction between zinc salt solution and sodium sulfide solution, followed by calcination under nitrogen condition, and concluded with grounding by sand mill. The particle size, crystal structure, and whiteness of ZnS NPs were analyzed by various characterization tools. Importantly, the crystal structures of ZnS NPs were transformed from sphalerite to wurtzite during the calcination process, without any change after sand grinding. ZnS/Polypropylene (ZnS/PP) composites were prepared by melt blending method, and then hot pressing into sheets. ZnS/PP composites exhibited better thermal stability than neat polypropylene from the thermogravimetric and limiting oxygen index analysis. ZnS/PP composites also improved the tensile strength and elongation at break of PP. Moreover, the morphology of the tensile fracture surface of ZnS/PP composites showed the uniform distribution of ZnS NPs within PP matrix and the ductile fracture mode. We anticipate that this work may shed light on fabricating efficient ZnS NPs and thermal stable ZnS-polymer composites.