Boosting solubility performance of supercritical CO2 via ethanol toward fabrication of polyetherimide/carbon fiber composite foam with three-dimensional geometry shape

The demand for light-weight, high-performance polymeric foam material, and part soars to meet the requirements of the national economy and the high-tech industries. Currently, foaming technologies are inadequate to fabricate these advanced materials. In this study, polyetherimide/carbon fiber (PEI/CF) foam was prepared by pressure-induced batch foaming technology with the supercritical CO2 (scCO(2)) and ethanol (EtOH) as the physical foaming agent and co-foaming agent, respectively. The presence of EtOH was verified to enhance the solubility of scCO(2) and increase the interaction energies between PEI molecular chain and CO2/EtOH foaming agent, the expansion ratio of PEI pellets, as a result, was effectively improved from 1.3 to 7.5. Using the stainless mold-assisted sinter molding, numerous PEI or PEI/CF pellets was simultaneously foamed and squeezed into three-dimensional (3D) geometry shape. The cell morphology tests indicated that the CF, served as the nucleating agent, cannot only facilitate the formation of denser microcellular structure, but also improve the mechanical performance of the final foam product. As a model system, PEI/CF foam product with a density of 320 kg/m(3) was successfully obtained, the compression and tensile strength of which were 11.6 and 9.7 MPa, respectively, as proved by the mechanical performance measurements.