摘要
研究了应用超临界CO2技术制备微孔聚丙烯时发泡条件和聚丙烯(PP)的熔体强度对微孔形貌的影响。结果表明:在一定的饱和压力下,随着温度的升高,PP的变形能力改善,有利于泡孔的长大。随着饱和压力的增加,PP的熔点降低,升高压力和升高温度具有一定的等同作用。由于CO2在PP内分散的不同,高压低温时得到的泡孔比高温低压时得到的泡孔要规整。降压速率对泡孔形貌的影响因饱和压力的大小而异,饱和压力较高时随着降压速率的提高,孔密度增加,泡孔形貌经历了一个从球体到多面体转变的过程。由于PP熔体强度较低,在发泡温度和PP熔点之间非常接近时,CO2气体容易冲破孔壁而使泡孔呈开孔结构。
The cell morphology of the microcellular polypropylene（PP） foams prepared by supercritical carbon dioxide was studied. According to the results, as the foaming temperature increased at a given saturation pressure, the cell size increased for an increase in the deformability of the PP. There is a sort of equivalence between increasing foaming temperature and increasing saturation pressure in terms of the foamability. The cell obtained at a higher saturation pressure with a lower foaming temperature is more uniform than that obtained at a lower pressure with a higher foaming temperature because of the different diffusivity of COz in PP. The effect of pressure drop rate on cell morphology varies with the magnitude of saturation-pressure. At higher saturation pressure, as the pressure drop rate increases, the cell density increases and the cell shape evolves from globule to polyhedron. Because of the low melt strength of PP, cell becomes open for CO2 gas in cell penetrated the cell wall when the foaming temperature and PP melting temperature is very close.
出处
《功能高分子学报》
CAS
CSCD
北大核心
2007年第1期21-26,共6页
Journal of Functional Polymers
基金
国家自然科学基金(20490200)
上海市科委重点实验室专项(041207030)
关键词
聚丙烯
微孔聚合物
微孔形貌
超临界CO2
polypropylene
microcellular polymer
cell morphology
supercritical carbon dioxide
