Nilesh K. Shrivastava

A strategy to achieve high electromagnetic interference shielding and ultra low percolation in multiwall carbon nanotube–polycarbonate composites through selective localization of carbon nanotubes

Here, we report a simple method that involves solution blending of polycarbonate (PC) in the presence of multiwall carbon nanotubes (MWCNTs) and commercial PC beads for the preparation of electrically conducting MWCNT–PC composites with high electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity at very low (∼0.021 wt%) percolation threshold (pc). Thus, electrical conductivity of ∼4.57 × 10−3 S cm−1 was achieved in the MWCNT–PC composites at an extremely low MWCNT loading (0.10 wt%) in the presence of 70 wt% PC beads in the composites. Finally, optimizing the ratio of PC beads and MWCNT loading in the composites, a very high EMI SE value (∼23.1 dB) was achieved at low loading (2 wt%) of MWCNT with 70 wt% PC beads. The effective concentration of MWCNT increases in the solution blended PC region with increasing the amount of PC beads. Thus, a strong interconnected conductive network structure of CNT–CNT is developed throughout the matrix and the presence of strong π–π interaction among the electron-rich phenyl rings of PC and MWCNT in the composites plays a crucial role in increasing the EMI shielding value and electrical conductivity of the MWCNT–PC composites.

Compatibilization Mechanism of Nanoclay in Immiscible PS/PMMA Blend Using Unmodified Nanoclay

Organically modified nanoclays have been reported to play the role of a compatibilizer for immiscible polymer blends. However, the mechanism of compatibilization by nanoclay has been reported differently. In this work, we investigated the exact mechanism of compatibilization of nanoclay in immiscible polystyrene (PS)/poly(methyl methacrylate) (PMMA) blend in the presence of sodium-montmorillonite (Na-MMT) through selective dispersion of clay in the matrix phase. Through a detailed investigation of the morphology of PS/PMMA/Na-MMT blend nanocomposites, the plausible mechanism behind the compatibilization effect of clay in immiscible blends has been proposed.

Effect of γ-PVDF on enhanced thermal conductivity and dielectric property of Fe-rGO incorporated PVDF based flexible nanocomposite film for efficient thermal management and energy storage applications

Here, we investigate the effect of thermal conductivity of γ-crystallites of PVDF in Fe-rGO/PVDF nanocomposite, which are of potential use as actuators and temperature sensors for thermal management applications. The formation of γ-crystallites help to increase the thermal conductivity of the nanocomposite up to 0.89 W mK−1 at low level of filler loading (3 wt%) and we showed that the thermal conductivity depends on the amount of crystalline polar γ-phase in addition to filler concentration. Although thermal conductivity depends on the crystallinity of the nanocomposite, here enhancement of thermal conductivity is not related only to crystallinity, as the crystallinity is decreased compared to neat PVDF. However the thermal conductivity increases because of the generation of a higher number of γ-crystallites of small size. Furthermore, the nanocomposite at low filler loading also shows high dielectric constant with low dielectric loss of the order of ≈57 and ≈0.13, respectively, at 1 kHz. Moreover, the energy storage property and its dependence on γ-crystallite size reveals that the material can also exhibit superior released energy density (1.45 J cm−3) as compared to pure PVDF.

An approach to reduce the percolation threshold of MWCNT in ABS/MWCNT nanocomposites through selective distribution of CNT in ABS matrix

In this article, we demonstrate a facile route to prepare ABS/MWCNT nanocomposites with high electrical conductivity at a significantly low percolation threshold of the CNT. The strategy involves in situ co-polymerization of styrene and acrylonitrile monomers in the presence of multi-wall carbon nanotubes (MWCNT) and commercially available acrylonitrile butadiene styrene (ABS) beads. A dramatic improvement in the electrical conductivity in the nanocomposites was evident with increasing content of ABS beads at a constant CNT loading, which might be explained in terms of the formation of a continuous network structure of CNTs throughout the in situ polymerized ABS matrix. Such selective dispersion of MWCNTs results in an electrical conductivity (3.01 × 10−7 S cm−1) in the nanocomposites at 30 vol% loading of ABS beads and 0.24 vol% loading of MWCNTs. An increase in electrical conductivity to 4.50 × 10−5 S cm−1 was evident when the ABS bead content was increased to 60 vol% at the same loading of MWCNTs. The morphological analysis of the nanocomposites indicates selective distribution of the MWCNTs in the in situ co-polymerized ABS phase of the nanocomposites leaving the externally added ABS beads free from CNT dispersion. This leads to an increase in effective concentration of the CNTs in the in situ co-polymerized ABS phase of the nanocomposites, which in turn creates a path of MWCNTs throughout the matrix, resulting in a decrease in the percolation threshold of the nanocomposites to a lower value (0.2 vol% MWCNT).

Effect of Filler Content on the Properties of Polypropylene/Saccharum spontaneum Green Composite

Current study focuses on the exploration of Saccharum spontaneum to fabricate polymer green composite in polypropylene matrix with malic anhydride-grafted compatibilizer. Analysis by thermogravimetric showed slight deviation in thermal stability only at higher kans grass-filler loading, but significant improvement was observed in tensile and impact strength. Storage modulus and loss modulus were reasonably increased and damping factor (tan δ) had no major deviation from base polymer. Fourier transform infrared spectroscopy peaks and morphological data suggest strong polymer-filler interfacial adhesion in the fabricated composite. Melt flow properties confirmed the processability with kans grass-filler content at 60 phr. GRAPHICAL ABSTRACT