Application of Graphene Oxide with Variable Spatial Structure as a Key to Polyethylene Foaming through Cured CO2 as Foaming Agent

Multifunctional and lightweight polymer foams exhibit a promising prospect, both nucleating and foaming agent play a crucial role among it. Moreover, nucleating agent with cavity structure showed a great influence on the cell morphology of foaming materials. In this work, nucleating agent hemicucurbit[6]uril@reduced graphene oxide (HQ[6]@RGO) was prepared through structurally variable reduced graphene oxide (RGO) complexing with hemicucurbit[6]uril (HQ[6]). Foaming agent 1, 2-cyclohexanediamine-CO 2 (TRK-CO 2 ) was obtained through curing CO 2 by using 1, 2-cyclohexanediamine (TRK) under normal temperature and pressure, and CO 2 can be reversibly released under heating. Finally, polyethylene (PE) foams were prepared with complex nucleating-foaming agent (HQ[6]@RGO: TRK-CO 2 ) through mold foaming process. The results showed that the specially designed HQ[6]@RGO: TRK-CO 2 based on the classical nucleation theory can effectively improve the foaming behavior of PE. The optimal cell morphology was obtained with 3 wt% HQ[6]@3 h-RGO: TRK-CO 2 , the minimum cell diameter was 84 μm and the maximum cell density was 15.6 × 10 4 cells/cm 3 . The crystallization performance and the viscoelasticity of PE foams were improved. With the assistance of excellent cell morphology, the impact strength was nearly doubled, the thermal conductivity was as low as 0.05 W/m·k and the highest acoustic absorption coefficient reached 0.886 for PE/HQ[6]@3 h-RGO: TRK-CO 2 with 3 wt% addition, compared with pure PE. Graphical