High-density polyethylene/carbon nanotubes composites: Investigation on the factors responsible for the fracture formation under tensile loading

Different concentrations (0.1, 0.2, 0.5, and 1 wt%) of OH-functionalized carbon nanotubes (CNTs) were used to prepare high-density polyethylene (HDPE) based composites via melt blending in the presence of a maleinized polyethylene (PE-g-MA) as a coupling agent. The mechanical behaviour of the produced HDPE/CNT composites was investigated in view of their possible application as reinforced materials in the civil structures and understood in terms of the structural modifications produced by the incorporation of CNTs in the HDPE matrix. The dispersion of CNTs in the polymer matrix, a key parameter to the ends of the mechanical performance of the composites, was evaluated at different observation scales, from few micrometers to some millimeters, by means of transmission electron microscopy (TEM), micro-Raman spectroscopy (MRS) and acoustic image analysis. The comparative discussion of the results obtained allowed clarifying the reason for the lack of a net improvement in the mechanical behaviour of the composites with respect to the pristine polymer.