The effect of polymer particle size on three-dimensional percolation in core-shell networks of PMMA/MWCNTs nanocomposites: Properties and mathematical percolation model

Segregated highly conductive percolation networks in nanocomposites consisting of a polymethyl methacrylate (PMMA) core and multi-walled carbon nanotube (MWCNT)-shell were investigated experimentally as a means of exploring the relationship between the micro-dimensional size of spherical polymer particles and the number of coated MWCNT layers by a new theoretical approach of filler monolayer model. The measured electrical conductivity of the core-shell structured complex utilizing 20 μm PMMA spheres showed that percolation was achieved at a very low filler content of 0.0099 wt% MWCNTs, whereas 0.149 wt% MWCNT was required to achieve percolation when 5 μm PMMA spheres were utilized. The size of PMMA cores was attributed to the percolation threshold, and conductivity was enhanced by increased layers of MWCNT coating. The percolation behaviors based on the theoretical model and experimental data were elucidated. Furthermore, an advanced theoretical model for prediction of number of MWCNT monolayers was provided.