Electrical and Structural Properties of HDPE/MWCNT/PE-g-MAH Nanocomposites Prepared Using Solution Mixing and Hot Compaction Two-Step Approach

Abstract

Background: MWCNTs tend to form agglomerates in nonpolar polymers due to their small size and high surface area. A promising approach to facilitate their dispersion within the polymeric matrix is based on employing a compatibilizer agent. Objective: The current study aimed to investigate the effect of a compatibilizer agent based on maleic anhydride grafted HDPE (PE-g-MAH) on the electrical and morphology properties of high density polyethylene/multi wall carbon nanotubes nanocomposites (HDPE/MWCNT/PE-g-MAH) prepared by solution mixing and hot compaction two-step approach. Methods: A two-step approach based on solvent mixing and hot compaction was used to prepare nanocomposites of HDPE/MWCNT/PE-g-MAH with different MWCNTs and PE-g-MAH contents. The electrical, morphology and HDPE crystalline structure properties of the nanocomposites were characterized by impedance spectroscopy, high resolution field emmision scanning electron microscopy and X-ray diffraction, respectively. Results: The results confirm the positive role of the PE-g-MAH compatibilizer in enhancing the dispersion of the MWCNTs and in turn the formation of more conductive pathways at low MWCNTs content in the nanocomposites. Adding 2 wt% of the compatibilizer to the nanocomposite of 1 wt% MWCNTs increases the electrical conductivity more than three orders of magnitude. Increasing the MWCNTs concentration more than 1 wt% leads to a limited enhancement in conductivity of the nanocomposite prepared using 2 wt% of PE-g-MAH compatibilizer. Meanwhile, the morphological characterization revealed that the limited increase in conductivity of nanocomposites with only 1 wt% compatibilizer is related to a substantial increase in the HDPE crystallinity (from 14.8 to 43.9%) induced by the enhanced nucleating effect of the dispersed MWCNTs. The excess HDPE crystalline regions suppress the formation of effective MWCNTs conducting pathways due to their confinement into smaller inter-crystallite regions in the nanocomposite. Conclusion: Therefore, a balanced role of the compatibilizer between dispersion of the MWCNTs and the nucleation of more HDPE crystallites has to be achieved by carefully selecting the compatibilizer type and concentration.