Design of continuous segregated polypropylene/Al2O3 nanocomposites and impact of controlled Al2O3 distribution on thermal conductivity

Control of nanoparticle distribution in polymer matrices is a key factor for designing highly conductive nanocomposites. Here, polypropylene (PP)/aluminum oxide (Al2O3) nanocomposites with a continuous segregated structure were designed. Al2O3 nanoparticles were initially distributed in the polyolefin elastomer (POE) phase of PP/POE/Al2O3 with a co-continuous structure. Selective extraction of the POE phase provided a porous PP scaffold, whose pore walls were covered by deposited Al2O3 nanoparticles. Subsequent compression molding made the porous scaffold tightly compacted to form uniform and dense thermal conductive networks. The thermal conductivity was compared among nanocomposites having three different types of Al2O3 distribution. It was found that the continuous segregated distribution was far the most effective for improving the thermal conductivity, where 1.07 W/m K was achieved at an Al2O3 loading of 27.5 vol%.