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The influence of epoxidation level of natural rubber (i.e., ENR25, ENR50) on the dielectric and oxygen gas barrier properties of thermally reduced graphene oxide (GR) and graphite (GT) (with 2%·w/w) filled nanocomposites are investigated here. GR, GT filled epoxidized natural rubber (ENR) nanocomposites were fabricated by mechanical mixing using environment friendly two‐roll mill mixing method. Raman spectroscopy and Fourier transform infrared spectroscopy studies were carried out to investigate the extent of chemical interactions between GR and ENR. Morphological studies were done using transmission electron microscopy to evaluate the distribution of GR and GT in the ENR. The improved gas barrier and dielectric properties of GT‐ENR and GR–ENR composites synthesized by a novel green ecofriendly method is correlated with the chemical interactions among GT, GR, and ENR. POLYM. ENG. SCI., 55:2439–2447, 2015. © 2015 Society of Plastics Engineers

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A simple and scalable fabrication process of graphene nanoplatelets (GnPs)-reinforced polyether ether ketone (PEEK) filaments with enhanced mechanical and thermal performance was successfully demonstrated in this work. The developed PEEK–GnP nanocomposite filaments by a melt-extrusion process showed excellent improvement in storage modulus at 30 °C (61%), and significant enhancement in tensile strength (34%), Young’s modulus (25%), and elongation at break (37%) when GnP content of 1.0 wt.% was used for the neat PEEK. Moreover, the GnPs addition to the PEEK enhanced the thermal stability of the polymer matrix. Improvement in mechanical and thermal properties was attributed to the improved dispersion of GnP inside PEEK, which could form a stronger/robust interface through hydrogen bonding and π–π* interactions. The obtained mechanical properties were also correlated to the mechanical reinforcement models of Guth and Halpin–Tsai. The GnP layers could form agglomerates as the GnP content increases (>1 wt.%), which would decline neat PEEK’s crystallinity and serve as stress concentration sites inside the composite, leading to a deterioration of the mechanical performance. The results demonstrate that the developed PEEK–GnP nanocomposites can be used in highly demanding engineering sectors like 3D printing of aerospace and automotive parts and structural components of humanoid robots and biomedical devices.

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Graphene-based materials are found as excellent resources and employed as efficient anti-microbial agents, and they have been receiving significant attention from scientists and researchers in this regard. By giving special attention to recent applications of graphene-based materials, the current review is dedicated to unveiling the antimicrobial properties of graphene and its hybrid composites and their preparation methods. Different factors like the number of layers, concentration, size, and shape of the antibacterial activity are thoroughly discussed. Graphene-based materials could damage the bacteria physically by directly contacting the cell membrane or wrapping the bacterial cell. It can also chemically react to bacteria through oxidative stress and charge transfer mechanisms. This review explains such mechanisms thoroughly and summarizes the antibacterial applications (wound bandages, coatings, food packaging, etc.) of graphene and its hybrid materials.

Exploiting polymer nanocomposites as dielectric and heat storage devices is an important approach to develop high performance materials. Graphite (GT), thermally reduced graphene oxide (TRG), and hybrid consisting of TRG and ionic liquid (1-Ethyl-2, 3-dimethylimidazolium bis (trifluoromethylsulfonyl) imide) modified carbon nanotubes (IMCNT) were added to natural rubber and membranes were fabricated via melt mixing method. The amount of the GT, TRG, TRG+IMCNT used in this work was in the range of 0.5 to 5 wt%. Mechanical properties of NR nanocomposites revealed that the hybrid (TRG+IMCNT) (5 wt%) system showed high tensile strength, high modulus and low elongation at break as compared to neat NR, NR reinforced with GT (5 wt%) and NR reinforced with TRG (5 wt%) systems owing to the synergistic hybrid effect caused by the network formation of the hybrid fillers inside NR matrix. Dielectric properties of the prepared membranes were studied at 2.5, 10 and 20 GHz in the microwave frequency region using a Split Post Dielectric Resonator (SPDR) based technique. The incorporation of micro and nanofillers in the natural rubber (NR) matrix results in consistent improvement in dielectric constant and lower loss tangent values. In certain cases the samples containing 5 wt% of filler exhibited high loss or conducting behaviour at higher frequencies (10 and 20 GHz). Different techniques had to be employed for measuring the dielectric constant and loss tangent of the prepared membranes where they showed a high loss or conducting behaviour. Moreover, thermal history like glass transition temperature and the change in heat capacity were estimated using Differential Scanning Calorimetry (DSC). In addition, the dispersion of micro and nanofillers inside the NR was estimated using X-ray followed by Transmission Electron Microscopy for the morphology architecture of nanofillers. The morphology of the prepared membranes was correlated with the mechanical, dielectric and thermal properties. The hybrid system (TRG+IMCNT) exhibited high dielectric constant (5.6) and low heat capacity value (0.32 J/g/°C) as compared to GT and TRG systems.