连续挤出发泡聚乳酸泡孔结构的影响因素

Factors affecting cell structure of continuous extrusion foaming poly(lactic acid)(PLA)

介绍了采用超临界CO2作为发泡剂,连续挤出聚乳酸泡沫塑料的方法。在不同的实验条件下,对聚乳酸进行挤出发泡,得到聚乳酸发泡样品。通过对样品的ESM照片的分析研究,得出了不同的发泡条件对挤出聚乳酸泡沫泡孔结构的影响。结果表明螺杆转速的增加使得泡孔数量增加,泡孔形态更加规整均匀。模头温度影响了泡孔形态,较高的温度会使得样品的泡孔形态受到不利的影响。水分的存在不利于聚乳酸发泡成为均匀发泡倍率高的泡沫制品。成核剂促进异相成核,使发泡样品的泡孔结构更加均匀,大大提高了聚乳酸泡沫塑料的泡孔密度。

This paper describes the method of continuous extrusion of polylactic acid foam using supercritical carbon dioxide as foaming agent.Under different experimental conditions,polylactic acid was extruded and foamed to obtain the sample of polylactic acid foam.Analysis of samples of ESM photo showed the effect of different foaming conditions on the cell structure of the extruded polylactic acid foam.With the increase of screw speed,number of ceils increased and cell morphology was more regular and uniform.Die temperature affected cell morphology,higher temperatures would adversely affect the sample cell morphology.The presence of moisture was not favorable to making polylactic acid foam product of high expansion ratio.Nucleating agent promoted heterogeneous nucleation and made the cell structure of the foam sample more uniform,greatly increasing polylactic acid foam cell density.