Ri Hanum Yahaya Subban

Polymer electrolyte films of poly (vinyl) chloride (PVC) as polymer host doped with ionic liquid 1-butyl-3-methylimidazolium trifluoromethasulfonate (BMIMCF₃SO₃) were prepared by solution cast technique. Ionic conductivity was studied for 95 wt.% and 80 wt.% PVC by using Impedance Spectroscopy (IS). Arrhenius and Vogel-Tamman Fulcher (VTF) behavior were observed before and after T_g of the systems. Fourier Transform Infrared (FTIR) study confirmed that complexation occurred between PVC and BMIMCF₃SO₃.

PVC/PEMA blend based polymer electrolytes with lithium bistrifluoromethane sulfonimide (LiN(CF₃SO₂)₂) and PVC/PEMA/(LiN(CF₃SO₂)₂-TiO₂ films were prepared by solution cast technique. The sample containing 35 wt. % LiN(CF₃SO₂)₂ exhibited the highest conductivity of 1.75 × 10⁻⁵ Scm⁻¹. The conductivity of the sample increased to 2.12 × 10⁻⁵ Scm⁻¹ and 4.61 × 10⁻⁵ Scm⁻¹ when 4 wt. % and 10 wt. % of titanium dioxide (TiO₂) was added to the sample at 65 wt. % PVC/PEMA-35 wt. % LiN(CF₃SO₂)₂ composition respectively. The low increase in conductivity is attributed to two competing factors: increase in crystallinity as accounted by X-Ray diffraction (XRD) and decrease in glass transition temperature as accounted by differential scanning calorimetry (DSC).

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

Hexanoyl chitosan-based polymer electrolytes were prepared using the solution casting technique. The effect of dimethyl carbonate (DMC) plasticizer on the structural and electrical properties of the prepared electrolyte system was investigated by X-ray diffraction and impedance spectroscopy, respectively. Upon addition of 15 wt. % of DMC, the ionic conductivity was increased to 4.09 x 10^-4 S cm^-1 from 3.06 x 10^-4 S cm^-1. The XRD results revealed the variation in conductivity from the structural aspect. For example, sample with lower crystallinity exhibits higher conductivity. The Rice and Roth model was employed to understand the variation in conductivity on the basis of number and mobility of free ions.

The intercalation of herbicide, 2,4,5-tricholorophenoxybutyrate (TBA) , into zinc-aluminium-layered double hydroxide (ZAL) for the formation of a new nanocomposite ZAT, was accomplished via anion exchange method. Due to the intercalation of TBA with ZAL interlayer domain, basal spacing expanded from 8.9Å in the ZAL to 23.3 Å in the ZAT. The percentage loading of TBA in the ZAT is 45.5 % (w/w). The FTIR spectra of the nanocomposite shows resemblance peaks of the TBA and Zn-Al-layered double hydroxide indicating the inclusion of TBA into the layered double hydroxide. Surface area of the resulting nanocomposite increased from 1.3 to 15.6 m²g^-1with the nitrogen adsorption-desorption of type IV, indicating the mesopore type of material.

Hexanoyl chitosan exhibited solubility in tetrahydrofuran (THF) was prepared by acyl modification of chitosan. Polystyrene with molecular weight 280,000 g mol^-1 was chosen to blend with hexanoyl chitosan. LiCF₃SO₃ was employed as the doping salt. Untreated and H₂SO₄ treated TiO₂ was added as the filler. Films of hexanoyl chitosan-polystyrene-LiCF₃SO₃-TiO₂ polymer electrolyte were obtained by solution casting technique. The ac conductivity of the sample was calculated from the relation σ_ac = ε_oε_iω, where ε_o is the permittivity of the free space, the angular frequency, ω=2πf, and ε_i is the dielectric loss. The ac conductivity dispersion observed is analyzed using the Jonshers universal power law, σ (ω) = σ_dc + Aωⁿ where A is a pre-exponential constant and n is the power law exponent with value in the range 0 < n < 1. The temperature dependence of exponent n will then be interpreted using the existing theoretical models.

Thermally reduced graphene oxide (graphene) filled natural rubber (NR) composites were fabricated by melt mixing method. Dielectric constant, dielectric loss and a.c conductivity data of the NR composites are reported. Highest conductivity of 3 x 10^-4 S/m was obtained for the composite with 3 wt. % graphene with initial electrical percolation at a loading of 0.5 wt. %. High conductivity in the composite with 3 wt. % graphene is accounted by its homogeneity as observed in SEM micrographs.