Synergistic Effect of Surface Area and Filler Loading of Graphene Nanoplatelets on High‐Density Polyethylene for Advanced Gas Barrier Applications

ABSTRACT The present investigation focuses on the synergistic effect of surface area and filler concentration of graphene nanoplatelets (GNPs) on the mechanical, thermal, and gas barrier properties of High‐Density Polyethylene (HDPE). In this study, HDPE graphene nanocomposites incorporated with two grades of graphene with different surface area (TG‐100 m 2 /g and SG‐550 m 2 /g) by varying composition from 0.05 to 0.2 wt.% were prepared by melt intercalation using a co‐rotating twin screw extruder. Helium and hydrogen permeability showed a 59% reduction for HDPE‐TG (HTG) composite with 0.05 wt. % filler loading and HDPE‐SG (HSG) composite showed a 65% reduction with 0.15 wt. % filler loading. HTG & HSG composite with 0.1 wt. % filler loading exhibited improved thermal and mechanical properties when compared with neat matrix. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) revealed that homogenous dispersion and in plane alignment of high surface area GNPs led to improvement in the gas barrier properties of HSG composites. X‐ ray Diffraction (XRD) provided deeper insights into the crystalline characteristics and dispersion of nanofiller. Degradation temperature and melting point were obtained by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Degradation temperature of both HTG and HSG composites showed only a slight increase of 5°C while melting point exhibited an increase of 12°C with 0.1 wt. % filler loading compared with pristine polymer. Tensile strength, Flexural strength and Izod impact strength of HTG composite showed a 15% hike while HSG composites exhibited a 12% increase when compared with virgin. Neilsen and Bharadwaj permeation models fitted well with experimental values for both HSG and HTG composites. This improvement in thermal, mechanical and gas barrier properties suggest its suitability in advanced barrier applications.