摘要
本文将聚丙烯(PP)、聚苯乙烯(PS)和羧基化多壁碳纳米管(MWCNT-COOH)在双螺杆挤出机中熔融共混,结合超临界二氧化碳(scCO2)微孔发泡技术制备用于油水分离应用领域的高发泡倍率、高开孔率的PP复合泡沫材料.通过复合材料的相形态、流变、差示扫描量热分析(DSC)、scCO2发泡和重复吸油测试对复合材料的微观结构、黏弹性、结晶性、微孔发泡行为和重复吸油性能展开研究.PS和MWCNT-COOH可以协同提高PP基体的熔体强度,MWCNT-COOH对PP结晶的促进作用强于PS.在PS和MWCNT-COOH协同异相成核作用下,含有10%质量分数的PS、1%质量分数的MWCNT-COOH的PP复合泡沫材料的泡孔密度为4.5×108 个/cm3,发泡倍率为 22.5 倍,开孔率为 89%,对硅油和环己烷的最大吸油量分别为 19、13.4 g/g,10 次循环压缩后泡沫永久形变仅为25%,吸油量分别仍能达到13.8、10.1 g/g.
Abstract
Polypropylene(PP),polystyrene(PS)and carboxylated multi-walled carbon nanotubes(MWCNT-COOH)were melt-blended using a twin-screw extruder in this study.Supercritical carbon dioxide(scCO2)foaming technology was then used to prepare PP-based composite foams with high foaming ratio and high open-cell content for oil-water separation applications.The microscopic structures,viscoelasticity,crystallinity,foaming behaviors,and repetitive oil absorption performance of the PP-based composites were characterized through morphology,rheology,differential scanning calorimetry(DSC),scCO2 foaming and repetitive oil absorption tests.The results show that PS and MWCNT-COOH can synergistically enhance the melt strength of PP matrix.Compared with PS,MWCNT-COOH exhibits stronger promotion effect on PP crystallization.Under the synergistic heterogeneous nucleation function of PS and MWCNT-COOH,the PP-based syntactic foam containing PS with a mass fraction of 10%and MWCNT-COOH with a mass fraction of 1%exhibits a cell density of 4.5×108 cells/cm3,a foaming ratio of 22.5 and an open-cell rate of 89%.Besides,its maximum oil absorption capacities for silicone and cyclohexane are respectively 19 g/g and 13.4 g/g.Even after 10 compression cycles,the permanent deformation of the foam retains only 25%,and the oil absorption capacities for silicone and cyclohexane still maintain at 13.8 g/g and 10.1 g/g,respectively.
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