Effect of solid-state shear milling on the physicochemical properties of thermally conductive low-temperature expandable graphite/low-density polyethylene composites

Low-temperature expandable graphite (LTEG)/low-density polyethylene (LDPE) composites with high thermal conductivity were prepared via an in situ expansion melt blending process. Solid-state shear milling (S3M) was applied to further improve the physicochemical properties of the composites. X-ray diffraction (XRD) and scanning electron microscopes (SEM) confirmed the exfoliation of the graphite layers into graphite nanoplatelets (GNPs) and subsequent relatively homogeneous dispersion of GNPs in LDPE matrix with improved interfacial adhesions by S3M. Furthermore, orientation of GNPs in the composites is formed after S3M treatment especially at high LTEG loading. Consequently, the S3M treated composites show a significant enhancement in mechanical properties compared to the untreated samples, as well as better crystallization and thermal properties. Moreover, the thermal conductivity of the composite at 50 wt% graphite loading is as high as 5.04 W/m K.