Gas Barrier, Thermal, Mechanical and Rheological Properties of Highly Aligned Graphene-LDPE Nanocomposites

Abstract

This contribution reports on properties of low-density polyethylene-based composites filled with different amounts of graphene nanoplatelets. The studied samples were prepared in the form of films by means of the precoating technique and single screw melt-extrusion, which yields a highly ordered arrangement of graphene flakes and results in a strong anisotropy of composites morphology. The performed tests of gas permeability reveal a drastic decrease of this property with increasing filler content. A clear correlation is found between permeability and free volume fraction in the material, the latter evaluated by means of positron annihilation spectroscopy. A strong anisotropy of the thermal conductivity is also achieved and the thermal conductivity along the extrusion direction for samples filled with 7.5 wt % of GnP (graphene nanoplatelets) reached 2.2 W/m·K. At the same time, when measured through a plane, a slight decrease of thermal conductivity is found. The use of GnP filler leads also to improvements of mechanical properties. The increase of Young's modulus and tensile strength are reached as the composites become more brittle.

Highly structured graphene polyethylene nanocomposites

“…The nanoplatelets are aligned along the extrusion flow direction. This effect was also observed in our earlier study [3,5]. The difference in size between fillers is visible, however some agglomerates are present in both samples.…”

“…Properties of the nanoplatelets and molecular weight parameters of the LDPE, measured by means of Gel Permeation Chromatography and DSC, are presented in Gaska et al [3,5] Graphene nanopletelets were dispersed into acetone and stirred by high shear rotor stator mixer for 20 minutes at 10 000 rpm, then sonicated for 3h, 90W. Thereafter graphene-acetone suspension was mixed with LDPE in the powder form for 1h at 500 rpm using overhead stirrer until total solvent evaporation.…”

Graphene/Polyamide Laminates for Supercritical CO2 and H2S Barrier Applications: An Approach toward Permeation Shutdown

“…Pierleoni et al also investigated filtered papers of GNPs and reported that even at graphene loadings as low as 0.4 wt%, a 74% depreciation in oxygen permeability could be achieved. An alternative route to improve the fluid barrier performance of thermoplastic polymers is through incorporation of GNPs via melt processing . Gaska et al achieved improvements in barrier performance of low‐density polyethylene (LDPE) to CO 2 and SF 6 of 65.5 and 80.5%, respectively, for LDPE loaded with 7.5 wt% GNP.…”

“…An alternative route to improve the fluid barrier performance of thermoplastic polymers is through incorporation of GNPs via melt processing . Gaska et al achieved improvements in barrier performance of low‐density polyethylene (LDPE) to CO 2 and SF 6 of 65.5 and 80.5%, respectively, for LDPE loaded with 7.5 wt% GNP. Checchetto et al found 5 wt% GNPs reduced LDPE permeability to H 2 , N 2 , and CO 2 by ≈40%.…”

Antibacterial effect of boron nitride flakes with controlled orientation in polymer composites

“…All the samples were etched for 30 h using a solution of 1% w/w potassium permanganate in a mixture of 98% of sulfuric acid, 85% of ortho-phosphoric acid and water. 37 The process was terminated by cleaning the samples in a mixture of sulfuric acid and deionized water, thereaer in hydrogen peroxide and next in deionized water.…”