Synthesis and Characterization of Poly(N-vinylcarbazole)/Graphene Nanocomposites.

The present work describes the dual role of graphene as an initiator and filler for polymerization of N-vinylcarbazole and formation of poly(N-vinylcarbazole)/graphene (PVK/Gr) nanocomposites. Fourier transformation infrared (FTIR) and X-ray diffraction (XRD) studies confirmed the formation of PVK as well its graphene nanocomposites. Scanning electron micrograph (SEM) and transmission electron microscopy (TEM) revealed the graphene platelets are dispersed in the matrix of spherical PVK. X-ray photoelectron spectroscopy (XPS) also revealed formation of PVK and presence of interaction between PVK and graphene. Thermograivmetric analysis (TGA) have shown that the thermal stability of PVK/graphene (0.5 wt%) is maximum improved by -76 degrees C compared to neat PVK, when 20 wt% weight loss is taken as a point of comparison. Ultraviolet (UV) and photoluminescence (PL) studies established the charge transfer from polymer chains to the graphene platelets. Dielectric measurements have shown the maximum improvement (87%) in dielectric constant (ε) with 1 wt% graphene loading. The variation of ac conductivity (σ) with frequency (ψ) confirmed the insulating behavior of PVK/graphene nanocomposites possessing high dielectric constant.

Reinforcement of ball shaped MoS2 nanoparticles in epoxy resin.

The present work involves the synthesis of molybdenum disulfide (MoS2) nanoparticles by annealing the precursor obtained from simple reflux method. XRD, FESEM and HRTEM confirmed the formation of 2H-MoS2 with ball shaped particles, where some of them possess coalesced dumbbell morphology. The reinforcement of polysulphide modified epoxy resin (PSER) by MoS2 with varying amounts from 0.150 to 0.200 wt% provides unique combination of the improved thermal stability, tribological and mechanical properties. XRD studies indicate interaction between the sulphur containing nanoparticles and the epoxy resin. Maximum improvements in tensile strength (440%) and toughness (534%) are observed with ball shaped MoS2 nanoparticles (0.150 wt%)/PSER composite. Also the coefficient of friction and wear resistance show improvements of 60 and 78% respectively for 0.175 wt% loading in PSER compared to the neat resin matrix. Thermal stability is found to be improved maximum by 23 degrees C, when 5% weight loss is taken as a point of comparison. Similar studies on synthetic microcrystalline MoS2 filled PSER show that improvements in all these properties are very inferior.