Simultaneous Improvement in Structural Properties and Microwave Shielding of Polymer Blends with Carbon Nanotubes

Abstract

Precisec ontrol in dispersing nanostructured materials in ap olymer blend structure is ak ey requirement in designing materials with tailor-made properties. In this study, the dispersion of ac onducting additive (multiwalledc arbon nanotubes, MWNTs) in ac o-continuous polymer blend structure was controlled by introducing surface-active groups, which react in situ and localize in the thermodynamically nonpreferred phase. In addition, by modifying the MWNTs with am acromolecule, which is mutuallym iscible with the entities, the nanoscopic particles can be localized at the interface. This way,d ifferent MWNTs can be positioned in different phases under macroscopic processingc onditions. Herein, we report that this unique strategy has led to simultaneous enhancement in both mechanical strength and electrical conductivity of the blend nanocomposites. In addition, intriguingly,t he microwave shielding efficiency can also be tuned by this ordered arrangement of MWNTs in the blend structure in strikingc ontrast to when the MWNTsa re in the thermodynamically favored phase. An outstanding two-fold enhancement in the Young'sm odulus, as comparedt oc ontrol blends,a nd an impressive bulk electrical conductivity of 1Sm À1 was noted for ap articular blend structure wherein different MWNTs were positioned in different phases. In addition, the best blend structure designed here also exhibited am inimum reflection loss (R L )o fa pproximately À61 dB and as hielding effectiveness of > 30 dB at 18 GHz. These data uncover the importance of polymer blends in designing lightweight electromagnetic interference (EMI) shielding materials.

Unique Multilayered Assembly Consisting of “Flower-Like” Ferrite Nanoclusters Conjugated with MWCNT as Millimeter Wave Absorbers

“…The lack of specific interactions between the immiscible polymer components generally result in heterogeneous morphology . A cocontinuous type of morphology is observed here when these two immiscible polymers (PC and PVDF) were mixed in 50/50 weight ratios (Figure a).…”

“…The lack of specific interactions between the immiscible polymer components generally result in heterogeneous morphology. 46 A cocontinuous type of morphology is observed here when these two immiscible polymers (PC and PVDF) were mixed in 50/50 weight ratios (Figure 3a). The SEM micrographs suggest that cocontinuous morphology is retained even after the addition of different nanoparticles (Figure 3b,c).…”

“…−40.9 dB at 9.8 GHz. 44 Herein, a well-studied immiscible system, PC/PVDF polymer blend, 45,46 was chosen to design millimeter wave absorbers wherein selective localization of nanoparticles in one of the components reduces the percolation threshold through effective increase in the local concentration of the functional nanoparticles. In order to absorb EM radiation, two key parameters, reasonably high conductivity and loss characteristics, were achieved by incorporating MWCNTs and magnetic "flower-like" Fe 3 O 4 nanoclusters.…”

Does the Type of Polymer and Carbon Nanotube Structure Control the Electromagnetic Shielding in Melt-Mixed Polymer Nanocomposites?

“…High loading of these fillers usually results in high melt viscosities, inferior mechanical properties, and low economic affordability [7]. Since the discovery of carbon nanotubes (CNTs), alluring properties simply change the mind of the researchers and CNTs have been utilized enormously in the polymer matrix as potential fillers [8][9][10]. The high aspect ratio, high electrical conductivity, and low percolation threshold in a suitable matrix are the most critical parameters for any polymer based shield designing [11,12].…”

Interfacial Architecture Constructed Using Functionalized MWNT Resulting in Enhanced EMI Shielding in Epoxy/Carbon Fiber Composites

“…Improved interface reduces the possibility of debonding and hence increases the load-bearing property of the composite . Considering these requisites, researchers have continuously attempted to functionalize carbon fiber or epoxy resin with various nanoparticles, such as clay, graphene, montmorillonite, and carbon nanotubes (CNTs), to obtain enhanced properties depending on a wide range of applications. − Owing to the exceptional mechanical, electrical, and thermal behaviors, CNT have always attracted the attention of researchers. , In one of the studies by Kepple and co-workers, multiwalled carbon nanotube (MWNT) was grown on carbon fiber using the chemical vapor deposition technique and four layered composites were prepared using structural epoxy. These composites were subjected to fracture testing, and fracture toughness was increased by 50% with no structural stiffness loss .…”