Unpredictable dispersion states of MWNTs in HDPE: A comparative and comprehensive study

A review of the literature indicates a wide range of dispersion states of carbon nanotubes (CNT) in high density polyethylene (HDPE), with in some cases, formation of micro-composites with bundle-like aggregation of the nanoparticles and in some others, much finer nanotube dispersion leading to higher performance (nano)composite materials. This contribution emphasizes the diversity of these results by comparing the dispersion state of different types of multiwall carbon nanotubes (MWNT) blended within several grades of HDPE via melt processing. It appears that each combination leads to a different dispersion quality. This study highlights that there is not a universal method to blend CNT and HDPE and that the dispersion state of the nanotubes is not readily predictable. Actually, inherent affinity between CNT and polyethylene proved to be rather great but melt viscosity and processing conditions represent key-parameters to be considered for allowing dissociation and dispersion of the nanoparticles within the polyolefinic matrix.