Lencar Calin Constantin, Ramakrishnan Shashank, Sundararaj Uttandaraman
Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
Nanomaterials (Basel). 2022 Oct 26;12(21):3772. doi: 10.3390/nano12213772.
In this work, the effects of MWCNT concentration and mixing time on the migration of multi-walled carbon nanotubes (MWCNTs) within polyethylene oxide (PEO)/polyethylene (PE) blends are studied. Two-step mixing used to pre-localize MWCNTs within the PE phase and subsequently to observe their migration into the thermodynamically favored PEO phase. SEM micrographs show that many MWCNTs migrated into PEO. PEO/PE 40:60 polymer blend nanocomposites with 3 vol% MWCNTs mixed for short durations exhibited exceptional electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity (14.1 dB and 22.1 S/m, respectively), with properties dropping significantly at higher mixing times, suggesting the disruption of percolated MWCNT networks within the PE phase. PE grafted with maleic anhydride (PEMA) was introduced as a compatibilizer to arrest the migration of MWCNTs by creating a barrier at the PEO/PE interface. For the compatibilized system, EMI SE and electrical conductivity measurements showed a peak in electrical properties at 5 min of mixing (15.6 dB and 68.7 S/m), higher than those found for uncompatibilized systems. These improvements suggest that compatibilization can be effective at halting MWCNT migration. Although utilizing differences in thermodynamic affinity to draw MWCNTs toward the polymer/polymer interface of polymer blend systems can be an effective way to achieve interfacial localization, an excessively low viscosity of the destination phase may play a major role in reducing the entrapment of MWCNTs at the interface.
在本研究中，研究了多壁碳纳米管（MWCNT）浓度和混合时间对其在聚环氧乙烷（PEO）/聚乙烯（PE）共混物中的迁移的影响。采用两步混合法将MWCNT预先定位在PE相中，随后观察其向热力学上更有利的PEO相的迁移。扫描电子显微镜（SEM）显微照片显示，许多MWCNT迁移到了PEO中。含3体积%MWCNT且短时间混合的PEO/PE 40:60聚合物共混物纳米复合材料表现出优异的电磁干扰屏蔽效能（EMI SE）和电导率（分别为14.1 dB和22.1 S/m），但在较长混合时间下性能显著下降，这表明PE相内的MWCNT渗流网络被破坏。引入马来酸酐接枝的PE（PEMA）作为增容剂，通过在PEO/PE界面处形成屏障来阻止MWCNT的迁移。对于增容体系，EMI SE和电导率测量结果表明，在混合5分钟时电性能出现峰值（15.6 dB和68.7 S/m），高于未增容体系。这些改进表明增容可以有效地阻止MWCNT的迁移。尽管利用热力学亲和力的差异将MWCNT吸引到聚合物共混体系的聚合物/聚合物界面是实现界面定位的有效方法，但目标相过低的粘度可能在减少MWCNT在界面处的截留方面起主要作用。
