Expanded polypropylene (EPP) foam, is widely used in the field of packaging, automotive and toys, etc., and its preparation process is mainly obtained by semi-continuous autoclave bead foaming. Because foamed beads can be fabricated into complex 3D components and have excellent structural controllability. In contrast, a novel method for continuous production of expanded PP foamed beads is developed via supercritical CO₂ (scCO₂) extrusion foaming coupling with a wind cutting device, then the real-time cell growth and pelletizing processes of the extruded bead foams are revealed by using a high-definition camera for the first time. Interestingly, the processes of solubilization, compounding, pelletizing and foaming can happen in a one-step process through the above method, which can greatly shorten the production time, save energy consumption, and promote structural diversification. Besides, the transformation of foamed beads, like spherical, cylindrical and dumbbell-shaped, can be achieved by adjusting the pelletizing speeds based on the Barus effect. Furthermore, the steam-chest molding of the extruded foamed beads into foamed product shows that it is possible to sinter the beads at a low steam pressure (2.0 bar). In addition, the as-prepared foamed products can withstand constantly treading by an adult, and the surface of the foamed product rises only ~7.5 °C after prolonged heating, illustrating the outstanding mechanical and thermal insulation properties. Finally, it can be imagined that the related technical route has important scientific significance for the development of other polymeric bead foaming systems.

膨胀聚丙烯（EPP）泡沫，广泛应用于包装、汽车和玩具等领域，其制备工艺主要是通过半连续高压釜珠粒发泡获得。因为泡沫珠可以制造成复杂的3D组件，并且具有出色的结构可控性。相比之下，通过超临界 CO ₂ (scCO ₂) 挤出发泡与风切装置耦合，首次使用高清摄像头实时揭示挤出珠粒泡沫的细胞生长和造粒过程。有趣的是，通过上述方法，增溶、复合、造粒、发泡等过程可以一步完成，可以大大缩短生产时间，节约能源，促进结构多样化。此外，根据巴鲁斯效应调整造粒速度，可以实现泡沫珠的球形、圆柱形和哑铃形的转变。此外，将挤出的泡沫珠粒蒸汽箱模塑成泡沫产品表明可以在低蒸汽压力（2.0巴）下烧结珠粒。此外，制成的发泡制品经得起成年人不断的踩踏，长时间加热后发泡制品表面仅上升约7.5°C，显示出优异的机械和隔热性能。最后，可以想象，相关技术路线对于开发其他聚合物珠粒发泡体系具有重要的科学意义。