Influence of mixing methods on the properties of high density polyethylene nanocomposites with different carbon nanoparticles

Abstract

In this paper, nanocomposites with multiwalled carbon nanotubes (MWCNT) or graphene nanosheets were prepared using a high density polyethylene (HDPE) matrix. Two different processes were employed: a solution method and a melt mixing method. The crystallinity index of the HDPE showed similar levels in nanocomposites after the addition of carbon nanotubes.  It can be seen that the preparation process modified the degree of crystallinity of the HDPE matrix with graphene nanosheets. Nanocomposites prepared by the solution method showed a decrease in the crystallinity index. The addition of carbon nanotubes led to an increase of Young´s Modulus with an increase in the MWCNT quantity, regardless of the preparation process used, with a 22.8 % increase for composites with 0.5 wt% of CNTs. The nanocomposites with graphene nanosheets exhibited a different behavior with each mixing method.  Nanocomposites prepared by the solution method showed a higher Young´s Modulus than those prepared by melt mixing. Results of transmission electronic microscopy and field emission scanning electronic microscopy indicated homogeneous dispersion for carbon nanotubes in melt mixing. Graphene nanocomposites showed some agglomerates, with smaller platelets in the nanocomposites prepared by solution mixing compared to that prepared by the melt mixing.

Keywords: nanocomposites, high density polyethylene, graphene, carbon nanotube, mixing methods