Barrier and Thermal Performance of Graphene-HDPE Nanocomposites for Pipeline Liner Application

The water barrier performance of high density polyethyelene (HDPE) nanocomposites with different graphene thicknesses and aspect ratios was investigated. Three graphenes with differing thicknesses and aspect ratios were considered for this work. The graphene was blended into the polymer HDPE matrix using a heated internal mixer. The best performing graphene in terms of improved barrier performance was determined to be the one that is thinnest and with the highest aspect ratio. This graphene was further studied for the effects of loading, whereby samples with 0.005, 0.01 and 0.10 wt% graphene, revealed no significant difference between them for enhanced barrier performance. In addition, the degree of crystallinity was also measured and compared between the unmodified and the three graphene modified HDPE. Between the three graphene-HDPE variants, there was no discernible difference in the level of crystallisation of the HDPE. However, it was shown that crystallinity improves by some 15%, corresponding to a measured degree of crystallinity of 65% for the graphene-HDPE, versus 56% for the unmodified HDPE. Thermal stability, on the other hand, did not improve with addition of the three graphenes used in this work. It is believed that the graphene loading used in this work was is low to produce any observable enhancement in thermal stability.