Foaming of polypropylene with supercritical carbon dioxide
Foaming of polypropylene with supercritical carbon dioxide
复制标题
DOI：
10.1016/j.supflu.2006.09.007
复制
发表时间：
2007-06-01
影响因子：
3.9
通讯作者：
Yuan, Wei-Kang
中科院分区：
文献类型：
--
作者：
Xu, Zhi-Mei;Jiang, Xiu-Lei;Yuan, Wei-Kang
本工作旨在研究超临界二氧化碳(SCCO(2))对聚丙烯(PP)的发泡行为。考察了饱和时间、发泡温度、饱和压力和降压速率对泡沫结构和体积膨胀率的影响。确定了由发泡温度和饱和压力的上下限划定的可能的发泡区。发泡的上限由PP的熔体强度决定，而下限由PP的变形能力决定。无论饱和压力如何，最大可能发泡温度范围都很窄，只有4℃左右，说明PP的发泡性能较差。在发泡性方面，提高发泡温度和增加饱和压力之间存在着某种等价性。然而，较低的发泡温度和较高的饱和压力比较高的发泡温度和较低的饱和压力更有利于获得均匀的泡沫。在一定的发泡温度和饱和压力下，降压速率越大，泡孔密度越大。泡孔尺寸和泡沫体积膨胀率均随降压速率的增大而增大，在某一时刻达到最大值，然后随降压速率的进一步增大而减小。(C)2006爱思唯尔B.V.保留所有权利。
This work is aimed at studying the foaming behavior of polypropylene (PP) with supercritical carbon dioxide (scCO(2)). The effects of saturation time, foaming temperature, saturation pressure and depressurization rate on the foam structure and volume expansion ratio were investigated. A likely foaming zone delimited by the upper and lower limits for foaming temperature and saturation pressure was determined. The upper limit for foaming was dictated by the melt strength of the PP while the lower one by the deformability of the PP. The maximum likely foaming temperature range was very narrow, only about 4 degrees C, whatever the saturation pressure, showing the poor foamability of PP. There was a sort of equivalence between increasing foaming temperature and increasing saturation pressure in terms of the foamability. However, a lower foaming temperature and a higher saturation pressure were more favorable for obtaining uniform foam than a higher foaming temperature and a lower saturation pressure. At given foaming temperature and saturation pressure, increasing depressurization rate led to an increase in cell density. However, both the cell size and the foam volume expansion ratio first increased with increasing depressurization rate, reached a maximum at some point and then decreased with a further increase in depressurization rate. (C) 2006 Elsevier B.V. All rights reserved.