N. H. H. Abu Bakar

Effect of anion of lithium salt on the property of lithium salt-epoxidized natural rubber polymer electrolytes

Lithium salt, LiX (where X = BF4−, I−, CF3SO3−, COOCF3− or ClO4−), was incorporated into epoxidized natural rubber (ENR). Thin films of LiX-ENR polymer electrolytes (PEs) were obtained via solvent casting method. These electrolytes were characterized using SEM/X-mapping, FTIR, differential scanning calorimeter, thermogravimetry analysis, and impedance spectroscopy. The trend in thermal stability and ionic conductivity of LiX-ENR PEs follow LiBF4 > > LiCF3SO3 ~ LiCOOCF3 > LiI > > LiClO4. The LiClO4 hardly dissociates and formed LiClO4 aggregates within the polymer matrix that resulted in a PE with low thermal stability and low ionic conductivity. The LiCF3SO3, LiCOOCF3, and LiI, however, exert moderate interactions with the ENR, and their respective PEs exhibit moderate ionic conductivity and thermal property. The occurrence of epoxide ring opening and complexation or cross-linking reactions in and between the ENR chains that involve BF4− ions have produced a LiBF4-ENR PE with superior thermal property and ionic conductivity as compared to other PEs studied in this work.

Electrical and thermal behavior of copper-epoxy nanocomposites prepared via aqueous to organic phase transfer technique

The preparation, electrical, and thermal behaviors of copper-epoxy nanocomposites are described. Cetyltrimethylammonium bromide - (CTAB-) stabilized copper (Cu) particles were synthesized via phase transfer technique. Isopropanol (IPA), sodium borohydride (NaBH4), and toluene solution of diglycidyl ether of bisphenol A (DGEBA) were used as transferring, reducing agent, and the organic phase, respectively. The UV-Vis absorbance spectra of all the sols prepared indicate that the presence of Cu particles with the particles transfer efficiency is ≥97%. The amount, size, and size distribution of particles in the organosol were dependent on the content of organic solute in the organosol. The composites were obtained upon drying the organosols and these were then subjected to further studies on the curing, thermal, and electrical characteristic. The presence of Cu fillers does not significantly affect the completeness of the composite curing process and only slightly reduce the thermal stability of the composites that is >300°C. The highest conductivity value of the composites obtained is 3.06 × 10-2 S cm-1.

Rapid Degradation of Methyl Orange by Ag Doped Zeolite X in the Presence of Borohydride

Abstract A series of Ag nanoparticles impregnated on zeolite X (Ag-ZX) containing various amounts of Ag (in wt%) were prepared via impregnation method. The pristine zeolite X and Ag-ZX catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption desorption analyses and atomic absorption spectroscopy (AAS). The prepared catalysts were employed for the decolourization of methyl orange (MO) in the presence of potassium borohydride (KBH4). Various parameters such as the amount of Ag impregnated, MO concentration, KBH4: MO mole ratios, pH and catalyst reusability were investigated. It was found that the best decolourization efficiency was obtained when 0.06 g of Ag-ZX (6.7) catalyst was employed using a KBH4: MO mole ratio of 731: 1 at pH 5. The degradation process obeyed pseudo first-order kinetics.

Metal Chloride Induced Formation of Porous Polyhydroxybutyrate (PHB) Films: Morphology, Thermal Properties and Crystallinity

Polyhydroxybutyrate (PHB) films with highly porous structures were synthesized using a one phase system comprising of metal chloride/methanol/PHB/chloroform (MCl2/CH3OH/PHB/CHCl3). SEM analyses confirmed that the MCl2 (where M = Cu2+ or Ni2+) induced porous structures with pore sizes ranging from 0.3 - 2.0 μm. The average pore size increased with the increasing MCl2 content. There existed weak physical interactions between the PHB chains and MCl2 as revealed by FTIR and NMR spectroscopies. The residue of MCl2 in the porous PHB film does not exert significant influence on the thermal stability of PHB. Nevertheless, the crystallinity of the prepared film is enhanced, as MCl2 acts as the nucleation sites to promote the growth of spherullites.

Effects of sodium doping on phase composition and morphology of barium titanate particles

Tetragonal barium titanate (BaTiO3) was synthesized via sol-gel method and calcined at 900 °C. The crystal phase of barium titanate still remained after doping with sodium showing that the phase had not been distorted by dopants. However, an additional phase of sodium barium titanium oxide (Na1.7Ba0.45Ti5.85O13) was detected and is believed to be formed on the surface of particles. Surface microstructures of undoped BaTiO3 show no distinct shape and high agglomeration. These preparations described the effects of different calcination duration on the composition and shape and size of BaTiO3 particles. Upon doping with sodium, the morphology of the particles becomes distinct. However, with the effect of increasing calcination duration from 2 to 6 hours, the morphology of particles progressively transformed from cube to sphere. Particles agglomeration was still unavoidable. The average size of the particles varied slightly between 0.24 - 0.36 μm with narrow size distribution after calcination.