Polylactic acid (PLA) is a bio-based and biodegradable polymer. It is challenging to prepare PLA bead foams at a large scale in an efficient manner. Herein, beads of modified PLA are foamed by one-step anhydrous supercritical CO₂ extrusion. This dramatically shortens the production time, prevents the PLA from pyrohydrolysis, and avoids wastewater generation. The melt strength of the PLA is increased from 0.8 to 16.7 cN using a chain extender. The morphologies and microstructures of bead foams are analyzed. In the case of the PLA bead foam obtained by extrusion foaming combined with wind-cooling pelletizing technology, the expansion ratio is higher than 13, the pore morphology is typical cellular structures, and the surface is glossy. The advantages and shortcomings of the PLA beads are also investigated. It is beneficial to promote the continuous preparation of PLA bead foams and other polymer beads like PS, and PP, which can be used in the fields of green packing, sound absorption, cold-chain logistics, and so forth.

中文翻译：

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采用无水超临界CO2挤出发泡的挤出聚丙交酯珠粒泡沫

聚乳酸（PLA）是一种生物基且可生物降解的聚合物。以有效的方式大规模制备 PLA 珠粒泡沫具有挑战性。在此，改性PLA珠粒通过一步无水超临界CO _2发泡挤压。这大大缩短了生产时间，防止 PLA 热水解，并避免废水产生。使用扩链剂，PLA 的熔体强度从 0.8 cN 增加到 16.7 cN。分析了珠粒泡沫的形貌和微观结构。采用挤出发泡结合风冷造粒技术得到的PLA珠粒泡沫，发泡倍数高于13，孔形貌为典型的蜂窝状结构，表面有光泽。还研究了 PLA 珠的优点和缺点。有利于推动PLA珠粒泡沫和PS、PP等其他聚合物珠粒的连续制备，可用于绿色包装、吸声、冷链物流等领域。