Crystalline polymer functionalized non-oxidized graphene flakes for high gas barrier composites

High gas barrier polyethylene (PE) composites containing non-oxidized graphene flakes (GFs) were fabricated through solution blending. GFs were synthesized through ultrasonic-assisted electrochemical exfoliation of graphite. Then, GFs were functionalized via directly inducing PE molecular crystallization along their surface under proper temperature and PE/GFs ratio. The composites with only 0.5 wt% GFs gave a helium leak rate of 6.29 × 10⁻⁸ Pa m³/s at 0.6 MPa, outperforming pure PE with a decrease of 83.4%. In addition, the interface interaction between PE and GFs is very weak, and the cohesive energy is only 0.1448 J m⁻². Therefore, at high GFs concentrations (>0.5 wt%), the continuous weak interfaces between the GFs interconnected networks and PE will reduce the effective diffusion path to a certain extent, leading to the reduction of gas barrier efficiency. In general, this method offers great promise for barrier materials that can be utilized in lightweight high-pressure gas storage vessels.