Novel dynamic foaming technology for microcellular foamed polystyrene-nanoCaCO3 composites

A novel Electronicmagnetic Dynamic Plasticating (EMDP) technology was applied to promote the microstructure (namely, size, density, and distribution of microcells within samples) of microcellular foamed polystyrene-nanoCaCO3 composites in the microcellular foaming process. By using environmentally benign supercritical CO2 as a blowing agent and nanoCaCO3 as a nucleant, the composites were prepared by a self-made dynamic foaming experimental setup. Experimental investigation was performed to evaluate both the effects of dynamic processing conditions (i.e., vibration frequency and amplitude) and nanoCaCO3 content on the microstructure of the composites. The experimental results showed that the nanoCaCO3 content had a significant effect on the microstructure. When the content is below 3wt%, it is very effective to increase the cell density with the increase of the nanoCaCO3 content, while, when the content is over 3wt%, the cell density can be decreased and both the cell distribution and cell size of cells would become uneven with the increase of the nanoCaCO3 content. Since the mechanical vibration was introduced into the foaming process, both the microstructure of the composites and the dispersion of nanoparticles could be remarkably improved. Based on the theoretical analysis of shear energy in the dynamic shearing flow field, the effects of vibration on both the microstructure and dispersion of nanoparticles in the composites were taken into account in this paper.