Mohamad Kamal Harun

Kinetic and Thermodynamic Study of Cd2+ Adsorption onto Rubber Tree (hevea brasiliensis) Leaf Powder

A batch adsorption system was applied to study the adsorption of Cd 2+ ions from aqueous solution by Hevea Brasiliensis, HB leaf powder. The adsorption capacities and rates of Cd 2+ ions onto HB leaf powder were evaluated. Langmuir and Freundlich models were applied to describe the isotherms and isotherms constants. Equilibrium data agreed well with the Freundlich model. The kinetic experimental data correlated well with the pseudo-second-order kinetic model, indicating that the chemical sorption was the rate-limiting step.

Optical Characterization of Luminescence Polymer Blends Using Tauc/Davis-Mott Model

The optical and electronic structures of poly (N-carbazole) (PVK) blend with poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) and polyvinylpyrrolidone (PVP) in the same composition were investigated. Polymer coating was carried out using doctor blade technique on a glass substrate. Uv-vis and photoluminescence spectrum revealed that there are significant different results obtained between PVK, PVK:PVP and PVK:PVDF-HFP. The electronic parameters such as absorption edge (Ee), allowed direct bandgap (Ed), allowed indirect bandgap (Ei) and Urbach edge (Eu) were calculated by using Tauc/Davis-Mott Model. The value of Ee and Ed for PVK and PVK:PVDF-HFP almost same but there was significant different value between Eu and Ei.

Investigation on effects of substituents in N,N′-dibensylidene ethane-1,2-diamine towards corrosion inhibition on steel in 1M HCl

Abstract Schiff base compounds, namely, N,N′-dibensylideneethane-1,2-diamine (baen), N,N′-bis(4-chlorobenzylidene)ethane-1,2-diamine (cbaen), N,N′-bis(4-methyl benzylidene)ethane-1,2-diamine (mbaen) and 4-(((2-4-hydroxybenzylidene amino)ethylimino) methyl)phenol (hbaen) were tested as corrosion inhibitors on mild steel in 1M HCl via polarisation method. These compounds were synthesised from the corresponding substituted benzaldehydes and ethylenediamine. Results indicate that the presence of chloro, methyl and hydroxyl substituents enhance the inhibitive properties of N,N′-dibensylideneethane-1,2-diamine. Cbaen achieved the highest inhibition efficiency of 80·76% at 1 × 10–3 M.

Micro-Raman, Optical and Impedance Characteristics of CNT-Substituted Acrylate/CNT Nanocomposite Thin Film

Carbon nanotube (CNT) has been synthesized using camphor oil as a starting material via two-stage catalytic chemical vapor deposition. The as-synthesized CNT was then incorporated into acrylate matrix by suspension polymerization method, using various loading of CNT (as a filler) varied from 0.2 to 1.0 g with 0.2 g weight interval in the nanocomposite thin film. The acrylate/CNT nanocomposite thin film was characterized using micro-Raman, ultraviolet-visible and impedance spectrometer. As confirmed, the various loading of CNT had a significant impact on structural, optical and impedance characteristics. The paper contributes the recent achievements in material progress of CNT/polymer nanocomposite.

Excitation and Emission Properties of Poly(N-Carbazole)/Poly(vinylpyrrolidone) Blends Characterized by Fluorescence Spectroscopy

We present the results concerning the excitation and emissions spectra of Poly (N-carbazole) (PVK) blend with different compositions of polyvinylpyrrolidone (PVP). Doctor blade technique was used to coat the blended polymer on a quartz substrate. The influences of polymer composition to the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation, emission and Stokes shift for each samples. The variation of Full Width at Half Maximum (FWHM) for excitation and emission indicate that the variation in composition has affected on the fluorescence properties of the blended thin film polymer system. Fourier Transform Infrared (FTIR) spectroscopy reveals that the discrepancy in the emission and excitation properties of this polymer blending system is due to the discrepancy of infrared absorption peak in the carbazole functional group.

Characterization of poly (N-vinlycarbazole) blending with different composition by using polarized electronic spectroscopy

Polarized absorption and dielectric spectra of blended poly (N-vinlycarbazole) (PVK) with polyvinylpyrrolidone (PVP) in different composition ratiosare investigated. Polymer coating was carried out using doctor blade technique on a quartz substrate. The polarized optical source was produced by using the uv-vis sheet polarizer. The polarized absorption and dielectric spectrum for parallel and perpendicular reveal that there are different significant results obtained between PVK and PVP with various polymer compositions.The polarized optical properties such aspolarization, ρwere calculated.These spectra indicate that the anisotropic properties of each polymer blends is different from each other.

Effect of Salt Concentration and Humidity on the Ionic Conductivity of Poly(Vinylidene Fluoride–Hexafluoropropylene) (PVdF-HFP)

Polymer electrolytes consist of poly(vinylidene fluoride –hexafluoropropylene) (PVDF-HFP) and lithium trifluoromethanesulfonate, LiTf (LiCF3SO3) were prepared by dissolving in dimethylformamide (DMF) using solution casting method and further dried in vacuum oven. The conductivity of each sample was investigated using electrochemical impedance spectroscopy (EIS) method. The samples were measured in two different environments viz. in humidity chamber (40% RH; 27°C) and at ambient condition (~60% RH; 27°C). The maximum conductivity obtained for the samples in humidity chamber was 8.05 × 10-5 S/cm with addition of 35 wt% of LiTf. Meanwhile, the highest conducting samples (with addition of 45 wt% of LiTf) exhibited the ambient condition temperature of 1.11 ×10-4 S/cm. Further increased salt concentration from the optimize concentration values has reduced the conductivity of the polymer electrolyte. Dielectric permittivity studies revealed that samples showed the non-Debye behaviors

Electrodeposition of Salicylideneaniline and its Corrosion Behavior

Electrodeposition was carried out on mild steel surface in 0.3 M sodium hydroxide solution (70% distilled water: 30% ethanol) containing 0.1 M salicylideneaniline using cyclic voltammetry and chronoamperometry techniques. Both techniques show the formation of the films on the mild steel surface. The corrosion behavior of electrodeposited mild steel was studied using electrochemical impedance spectroscopy (EIS) technique at various immersion times in 0.5 M sodium chloride solution (NaCl). The study indicates that the resistance of mild steel against corrosion increases after being electrodeposited with salicylideneaniline. However the films tend to diminished after 24 hours being immersed in 0.5 M NaCl solution.

Thermal properties and morphologies of poly(ethylene terephthalate) in blends with epoxidised natural rubber of 25 and 50 mol.-% of epoxy content

Abstract Thermal properties and morphologies for polymer blends of poly(ethylene terephthalate) (PET) and epoxidised natural rubber with 25 mol.-% (ENR-25) and 50 mol.-% (ENR-50) epoxy contents were studied using differential scanning calorimeter (DSC) and polarising optical microscope (POM) respectively. The blends were prepared by precipitation method. Immiscibility of the components is revealed by observation of two glass transition temperatures T g that correspond to that of the neat constituents. Equilibrium melting points Tom of PET in blends was determined by applying Hoffman–Weeks stepwise annealing procedure. The degree of crystallinity of PET in blends with ENR-25 remains constant, whereas the authors observe an increase in the degree in blends with ENR-50. The rate of crystallisation of PET in blends is characterised by the reciprocal halftime t–10·5. It displays an Arrhenius-like behaviour with respect to temperature and it stays constant at isothermal crystallisation temperature (T c=constant) as long as PET is in excess. Rate of crystallisation of PET in the blends decreases exponentially as the T c increases. Dispersed phases of ENR-25 and ENR-50 in the matrix of PET can be observed when the content of PET is in excess.

An evaluation of microstructure and hardness properties of Zr added FeNiAlCoCr high entropy alloys

High Entropy Alloy (HEA) with at least 5 elements with equimolar ratios were developed to investigate the characteristics of Zr added in FeNiAlCoCrZrx (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0). HEAs were prepared by arc melting technique in Ar atmosphere and were remelted five times to ensure homogeneity. The microstructure and phase constitution of these alloys are examined by X-Ray diffraction (XRD) and Scanning Electron Microscope (SEM). The results show that addition of Zr to FeNiAlCoCr HEA resulted in multiple solid solution phases viz., BCC1, BCC2, FCC1 and FCC2 as evidenced by XRD patterns. Furthermore, presence of both BCC and FCC phases at higher Zr additions suggests that Zr did not preferentially promoted the solidification of either BCC or FCC phase. It can be observed from the FESEM micrographs that with different Zr additions, solidified microstructures of FeNiAlCoCrZrx alloys varied between completely eutectic microstructures to proeutectic and eutectic phase mixtures. From FESEM micrographs it can be suggested that different Zr contents have resulted in different solidification modes. Hardness of Zr added samples is higher compared to base HEA which is FeNiAlCoCr. It was observed that hardness values are higher when proeutectic phases were present compared to completely eutectic FeNiAlCoCrZr alloy (x=0.1).