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Two shot solution polymerized natural rubber/polyethylene oxide (NR/PEO) block copolymers are used as chelating exchanger for the metal ions Mn(II) and Fe(II). The polymer - metal ion chelates are prepared via solution batch adsorption method and are subjected to various characterisation techniques. Adsorption studies shows 96 and 63 % complexation for Mn(II) and Fe(III) ions, respectively. The 72 helical conformation of PEO and metal-etheric oxygen coordination are confirmed by FT-IR spectroscopy. The XRD results revealed the complete miscibility of metal ions and semi-crystalline nature of samples. The EDX analysis confirmed the presence of metal ions in the polymer chelates. Surface morphology is also studied using SEM and TEM techniques.

As the ever rising world population has led to increasing energy demand, it is necessary to develop efficient materials for energy storage applications. The enhancement of dielectric permittivity plays a significant role for designing materials for energy storage applications. Hence, composites with high dielectric permittivity are presently getting interest in academic and industrial research fields. In the present study, reduced graphene oxide (RGO) was compounded with plasticized poly (vinyl chloride) to obtain flexible composites which show both high dielectric permittivity and low dielectric loss. An enhancement of 57% in dielectric constant was obtained after the addition of RGO to poly (vinyl chloride). This enhancement can be attributed to the increased number of interfaces of polymer and filler that was observed by transmission electron microscopy. The interfacial polarization in the heterogeneous interface plays an important role in imparting dielectric performance. Effective dielectric permittivity values of the composites calculated using theoretical equations were found to be lower than the experimental values. The nanocomposites were also tested for the permeability of O2 which is very important for fabrication of energy storage devices. The permeability was decreased by 53% when compared to pristine poly (vinyl chloride). Hence, the enhanced dielectric permittivity as well as the impermeability to oxygen makes this material a suitable candidate for energy storage applications.

Understanding the rheological behaviour of thermoplastic nanocomposites is important to obtain a concrete knowledge of their processability. The viscoelastic properties of nanocomposites are a reflection of their morphology. The study of flow and deformation of nanocomposites provides essential information related to prevalent interactions in the system as well as contribution from the dispersion of incorporated nanofillers. In the present study, plasticized polyvinyl chloride/reduced graphene oxide nanocomposites (PPVC/RGO) were fabricated using melt mixing technique with different filler concentration. Flow behaviour of the nanocomposites was analyzed using small amplitude oscillatory shear (SAOS) measurements and it indicated an enhancement in the storage modulus (G′), loss modulus (G′′) and complex viscosity (η*) with RGO content. This can be attributed to very good dispersion and reinforcing effect of RGO in PPVC matrix as supported by TEM and FTIR results. Weak gel model is used to fit the rheological parameters and is found to be in excellent agreement with the SAOS experiments. Thermal history of the prepared nanocomposites was learned using differential scanning calorimetry. A shift in glass transition temperature (Tg) to higher temperature region could be seen, that manifest the effect of RGO in the amorphous portion of PPVC. An interesting property called secondary crystallinity was also found in these materials.

Improving the properties of polyvinyl chloride matrix by the incorporation of carbonaceous filler by melt mixing is an unusual thought in the polymer research. Here we incorporated reduced graphene oxide (RGO) as a filler into plasticized polyvinyl chloride (PPVC) matrix by melt mixing, an eco-friendly method. The effect of addition of filler in the morphology of the PPVC nanocomposites was analyzed by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM) and Raman spectroscopy. The mechanical response of the nanocomposites to an applied stress was studied. A 50% improvement in mechanical properties was obtained at a low filler loading. A decrease in elongation was observed at higher RGO loading. The dynamic mechanical analysis (DMA) of the nanocomposites indicated an increase in glass transition temperature of the PVC up on the addition of RGO. This has confirmed the confinement of PVC chains at the graphene surface. As a result, the storage modulus of the nanocomposites showed an increase up on the addition of the nanofiller. Theoretical values of the storage modulus were calculated using various theoretical equations. The effectiveness of filler on the storage modulus is estimated and is found to be consistent with the results obtained experimentally. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

Two shot solution polymerised NR/PEO block copolymer (BC) was used as an absorbent in this study. This polymer has got polyethylene oxide (PEO) immobilised on hydrophobic natural rubber and it was used for complexation studies with the selected 3d transition metal ions. The prepared complexes were subjected to various analytical techniques such as energy dispersive X-ray spectroscopy (EDX), Fourier Transform infrared spectroscopy(FTIR), Raman spectroscopy, X-ray diffraction (XRD) studies, extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near edge spectroscopy (XANES). EDX analysis confirms presence of the respective metal ion in each complex. FTIR spectroscopy reveals the 72 helical conformation of polyethylene oxide segments in BC which is retained with some deformation upon complexation. The BC-metal ion interaction is confirmed by broadening of the C-O-C triplet peak. XRD analysis revealed that PEO lattice undergoes expansion during complexation inorder to accommodate the respective metal ion. From the EXAFS results it was observed that each metal ion shows only one peak that corresponds to the oxygen shell indicating the presence of only one type of metal ion bonding. The EXAFS gives hexa coordinated pattern for Co(II), Ni(II) and Zn(II) complexes while a tetra coordination for the Cu(II) complex. Metal-oxygen distance in a given complex is constant and unique which varies with the metal ion. XANES shows a distorted octahedral symmetry (Oh) with sp3d2 hybridisation for the hexa coordinated complexes and a square planar symmetry with dsp2 hybridisation for the tetra coordinated complex. Feasibility of 1 s → 3d transition confirms +2 oxidation state of the metal ions. The combined result of EXAFS and FTIR shows the best fit structure of the complexes in which metal ions are encapsulated within the PEO helical tunnel.