Effects of selective distribution of alumina micro-particles on rheological, mechanical and thermal conductive properties of asphalt/SBS/alumina composites

Constructing thermal conductive pathways is an effective route to increase the thermal conductivity of thermal interface materials (TIMs). Asphalt/styrene-butadiene-styrene tri-block copolymer (SBS)/alumina composites with alumina micro-particles selectively distributed in SBS (denoted as asphalt/SBS/sd-Al2O3) were fabricated through pre-dispersion of alumina micro-particles in SBS, followed by compounding with asphalt. The effects of alumina distribution on the rheological, mechanical and thermal conductive properties of the asphalt-based composites were systematically studied. Compared with the composites with randomly distributed alumina, i.e., asphalt/SBS/rd-Al2O3, those with selectively and homogeneously distributed alumina micro-particles in SBS formed a continuous thermal conductive SBS/alumina network. Therefore, the asphalt/SBS/sd-Al2O3 composites displayed maximum thermal conductivity enhancement of ~35% at 30 vol% alumina. At 50 vol% alumina, the thermal conductivity of the asphalt/SBS/sd-Al2O3 composites reached ~0.99 W/mK, which is 400% higher than that of the asphalt/SBS blend (0.20 W/mK). Also, the asphalt/SBS/sd-Al2O3 composites possessed higher values of storage modulus, tensile strength and softening point. This work has provided a promising approach to fabricate high-performance and low-cost TIMs.