▎ 摘　　要

NOVELTY - Preparing high-expansion ratio polymer-based foam beads by secondary foaming comprises (i) placing the polymer-based beads in a high pressure kettle, introducing carbon dioxide gas, reaching the carbon dioxide gas to the supercritical state under the primary foaming condition, performing primary foaming of polymer-based beads in the supercritical carbon dioxide gas environment, and releasing the pressure is relieved to obtain the primary foamed beads, and (ii) introducing the primary foamed beads in the high pressure kettle, introducing physical foaming agent, performing secondary foaming under secondary foaming conditions, and releasing pressure. USE - The method is useful for preparing high-expansion ratio polymer-based foam beads by secondary foaming. ADVANTAGE - The method: has application prospects in important fields of high-tech industry; overcomes the problem that conventional foaming methods can only prepare foamed beads with a lower expansion ratio; broadens the application range of bead foaming in polymer materials; and prepares large and high expansion rate polymer foam products.