Micro- and nano-sized calcium carbonate toughened polystyrene.

Polystyrene (PS)/CaCO3 micro- and nanocomposites were prepared by melt mixing in a twin screw extruder using four particles with average diameters of 55 nm, 70 nm, 240 nm, and 10 /microm in various loadings. It was found that PS can be effectively toughened with 1 wt% cubic shaped CaCO3 particles (55 nm, 70 nm, 10 microm) achieving significant increases of impact strength by 52%, 95%, and 190% respectively relative to neat PS. However, the needle shaped nanoparticles (240 nm) were not effective for improving the toughness of the matrix. SEM analysis of the fractured surfaces indicated good fillers dispersion at the optimum filler loading of 1 wt%, and the cavitations-induced shear yielding in the polymer matrix are shown to be the main toughening mechanism.