发泡剂与螺杆转速对PP等挤出发泡性能的影响

Effects of Foaming Agent and Screw Speed on Extrusion Foaming Properties of PP,PE–LD and PLA

以BIH40为发泡剂,采用挤出成型工艺,分别制备了聚丙烯(PP),低密度聚乙烯(PE–LD)和聚乳酸(PLA)挤出发泡材料,研究了发泡剂含量和螺杆转速对这3种发泡材料挤出发泡性能的影响。结果表明,当螺杆转速为26 r/min时,随着发泡剂含量从0.5%增加到2.0%,3种发泡材料的发泡倍率均逐渐增大,PP和PE–LD的泡孔平均尺寸也增大,而PLA的泡孔尺寸先增大后减小。当发泡剂质量分数为2.0%时,随着螺杆转速从26 r/min提高到42 r/min,PP的发泡倍率增大,泡孔平均尺寸减小;PE–LD的发泡倍率和泡孔平均尺寸均先增大后减小;PLA的发泡倍率基本不变,泡孔平均尺寸略有下降。当发泡剂BIH40质量分数为2.0%时,在相同螺杆转速下,PLA的发泡性能要优于PP和PE–LD,其泡孔尺寸较PP和PE–LD更小更均匀,单位面积上的泡孔数量明显高于PP和PE–LD。

BIH40 was used as foaming agent and extrusion was applied to fabricate polypropylene （PP）, low density polyethylene （PE-LD） and polylactide （PLA） foamed materials. Effects of the foaming agent content and screw speed on the foaming properties of the three foamed materials mentioned above were studied. The results show that when the screw speed is set as 26 r / min, with the mass fraction of the foaming agent increasing from 0.5% to 2.0%, the expansion ratios of the three materials are gradually enhanced, the average cell sizes of PP and PE-LD increase, but the average cell size of PLA increases firstly and then decreases. While the mass fraction of the foaming agent is given as 2.0%, with the screw speed increasing from 26 r/min to 42 r / min, the average cell size of PP decreases and the expansion ratio increases. For PE-LD, the average cell size and expansion ratio first increase but then are reduced at the same screw speed changing condition. Moreover, the screw speed has less effect on the expansion ratio of PLA and the average cell size decreases slightly under higher screw speed. When the mass fraction of the foaming agent is 2.0%, the foaming properties of PLA are obviously belter than those of PP and PE-LD under same screw speed, the average cell size of PLA is more small and uniform than that of PP and PE-LD and the average cell number of PLA in the same fractured cross section area is clearly more abundant than that of PP and PE-LD.