In this article, poly (lactic acid) (PLA) was foamed via batch foaming using supercritical nitrogen as a physical blowing agent by two methods, conventional foaming process (CFP) and low-temperature foaming process (LTFP). The fabrication processes, cell morphologies, thermal properties, crystallization behavior, and electrical resistance of resulted foams were studied to investigate the effect of foaming on these properties of PLA. It was found that the foams resulted from CFP method have micrometric cell sizes, while LTFP method led to nanometric cell structure and high cell density. Also scanning electron microscopy showed that the PLA foams have a heterogeneous cellular structure. The results showed that the foaming process increased the melting point and degree of crystallinity of PLA, which led to decrease in the electrical resistance of samples.

中文翻译：

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使用超临界氮制备聚（乳酸）泡沫

在本文中，聚乳酸 (PLA) 以超临界氮作为物理发泡剂，通过常规发泡工艺 (CFP) 和低温发泡工艺 (LTFP) 两种方法通过间歇发泡进行发泡。研究了所得泡沫的制造工艺、泡孔形态、热性能、结晶行为和电阻，以研究发泡对 PLA 这些性能的影响。结果表明，CFP 法制备的泡沫具有微米级的泡孔尺寸，而 LTFP 法制备的泡沫具有纳米级泡孔结构和高泡孔密度。扫描电子显微镜也显示 PLA 泡沫具有异质的蜂窝结构。结果表明，发泡过程提高了PLA的熔点和结晶度，