聚四氟乙烯微粉对超临界CO2发泡聚丙烯泡孔结构及性能的改善  

Improving Cellular Structure and Property of Supercritical CO2 Foamed of Polypropylene via the Addition of PTFE Micropowder

作　　者：杨晨光[1,2] 赵全 张茂江 邢哲 吴国忠[1] YANG Chenguang;ZHAO Quan;ZHANG Maojiang;XING Zhe;WU Guozhong(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800;University of China Academy of Sciences, Beijing 100049)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院大学,北京100049

出　　处：《材料导报》2019年第21期3547-3551,共5页Materials Reports

基　　金：国防基础科研核科学挑战计划(TZ2018004);国家自然科学基金(11079048)~~

摘　　要：通过挤出制备了三种不同聚四氟乙烯微粉(PTFE)含量(1.0%、5.0%、10.0%,质量分数)的聚丙烯/聚四氟乙烯(PP/PTFE)共混物样品,采用超临界二氧化碳(scCO 2)作为物理发泡剂对样品进行间歇发泡,研究了发泡样品的微观泡孔结构,并分析其形成机理。结果表明:挤出剪切作用下由分散PTFE为原料制造的微粉可以变成具有一定长径比的纤维状,并相互缠结形成网状结构,进而显著增加PP的熔体强度。流变性能测试结果表明,在低频区PP/PTFE复数黏度增强更加明显;制备的PP/PTFE发泡材料具有良好的微孔结构,泡孔均匀性明显改善,且随着PTFE添加量的增加,发泡材料孔径变小(平均值约31 μm),孔密度增加10倍,达到7.4×10^8 cells/cm^3 ,这归因于在发泡过程中PTFE颗粒增强PP异相成核且较高的熔体强度保证了完整泡孔的形成。相比于纯PP泡沫材料,PP/PTFE(1.0%)泡沫具有较大的发泡倍率,发泡倍率可达8倍,拉伸应力从原来6 MPa增加到11 MPa,断裂伸长率从107%增加到230%。W ell-defined cellular structure of isotactic polypropylene (PP) foams with outstanding properties were prepared via supercritical carbon dio- xide (scCO 2) foaming of iPP blended with a small amount of polytetrafluoroethylene (PTFE) micropowder. PP/PTFE blend samples with PTFE contents of 1.0wt%, 5.0wt% and 10.0wt% were prepared using a regular co-rotating two-screw extruder and then the samples were foamed using scCO 2 as the physical blowing agent in a batch process. The results showed that the PTFE micropowder could be transformed into a fiber with a certain aspect ratio and entangled with each other to form a network structure after extrusion, which greatly increased the melt strength of PP/PTFE. Well-structured cell morphology of PP/PTFE foam was obtained. The cell size decreased from 87 μm to 31 μm as the loading of PTFE increasing and the cell density of PP/PTFE(10.0%) foam reached 7.4×10^8 cells/cm^3, which was more than 10 times higher as compared to the neat PP foam. In addition, the PTFE particles, and the growth of nucleated small cells in the multiple-phase system, were responsible for the enhanced heterogeneous nucleation of PP foaming with good cellular structure during the foaming process. Compared to the neat PP foam, PP/PTFE foams showed significantly improved tensile strength and tensile strain. Due to the remarkable decrease in cell size and increase in cell density , which increased from 6 MPa to 11 MPa and from 107% to 230%, respectively.

关 键 词：PP/PTFE共混物 超临界二氧化碳发泡 微孔形貌 熔体强度 拉伸强度 

分 类 号：TQ328[化学工程—合成树脂塑料工业]