Advanced Materials Research Vol. 501

Abstract: Natural rubber-grafted-poly(methyl methacrylate) containing 30 and 50 percent of methyl methacrylate (MMA) monomer per 100 parts by weight of the dry rubber content denoted as NR-g-PMMA 30 and NR-g-PMMA 50, respectively were prepared via emulsion polymerisation technique. The occurrences of graft copolymerisation of PMMA onto NR were confirmed by proton Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared (FTIR) following purifications. The reinforcement of rubber by fillers is of great practical and technical importance. Thus, these fillers are added to rubber formulations to optimize the properties to meet a given application or set of performance parameters. In this study, the effect of carbon black in NR-g-PMMA 30 and NR-g-PMMA 50 rubber compounds were evaluated. Our results demonstrated that tensile strength, elongation at break and compression set reduced, while the hardness and solvent resistance increased in the presence of carbon black filler in comparison to the unfilled compound.

Abstract: The current research was conducted to study the incorporation of phosphorus-based flame retardant (exolit OP 1230) and phosphonium salt treated montmorillonite (P-MMT) into polyol resin of polyurethane foam, with the purpose of imparting its compression properties and flammability resistance. To prepare the hybrid composite with a 2.5 wt% based on weight percentage of the overall weight of the system, fractions of exolit OP 1230 are mixed with P-MMT following a percentage ratio of 25/75, 50/50 and 75/25. The result of the mechanical property testing showed that the compression strength of composite was decreased with the presence of exolit OP 1230. However, the result obtained also demonstrated that the fire behaviour of the foam was improved. The study indicated that a combination of exolite OP 1230 and P-MMT generates a synergistic mechanism effect which could be used as an effective fire retardant as compared to sample with a 2.5% P-MMT alone. On the other hand, horizontal burning test following an ASTM D635 test procedure was conducted to determine the burning rate and bomb calorimeter model Ika C5003 was employed to detect the combustion enthalpy in this study. Finally, the findings of the analysis of the mechanical properties were further supported by the SEM micrographs.

Abstract: Green Monoliths (GMs) of self-adhesive carbon grain from fibers of oil palm empty fruit bunches were prepared by compression pressure at 1.43 × 107, 1.91 × 107 and 2.39 × 107 kg/m2, respectively. Activated carbon monoliths ACM-A, ACM-B and ACM-C prepared by CO2 activation from these GMs, respectively, were used as electrodes in supercapacitor cells which employed stainless steel 316L current collector and H2SO4 electrolyte. Evaluation of the electrochemical properties showed that ACM-A, ACM-B and ACM-C cells had specific capacitance of 30, 9 and 5 F/g, total ESR of 3.21, 4.95 and 7.33 Ω, specific power (maximum) of 173.41, 107.58 and 33.82 W/kg, and specific energy (maximum) of 0.67, 0.15 and 0.09 Wh/kg. These properties are directly associated with the surface area of the ACMs, i.e. 419, 336 and 302 m2/g for the ACM-A, ACM-B and ACM-C, respectively, indicating a direct effect of compression pressure on the physical and electrochemical properties of ACMs electrodes.

Abstract: Free standing polymer electrolyte films comprising of ammonium trifluoromethane sulfonate in poly(ethyl methacrylate) were prepared and characterized. The structural and electrical properties of the polymer electrolytes were investigated by X-ray diffraction and a.c. impedance spectroscopy, respectively. The formation of polymer-salt complex has been confirmed by Fourier transform infrared spectroscopy study. Conductivity of the polymer electrolytes increased with salt content. The highest ionic conductivity in the order of 10-5 S cm-1 at room temperature was achieved for the system with 35 wt% of ammonium salt. The temperature dependence of conductivity obeyed the Vogel-Tammam-Fulcher relation. The activation energy has been calculated from the VTF formalism. The ionic transference number of the mobile ions estimated by Wagner’s polarization method was close to unity for the highest conducting sample implying that the conductivity was contributed by ions which was expected to be protons.

Abstract: Pre-mixed NiZn ferrite/MWNT, according to the weight ratio 1:1, were incorporated into the thermoplastic natural rubber nanocomposite by melt blending process. The effect of different filler loadings (2-10 wt%) on reflection loss and shielding effectiveness of the obtained composites were studied. It was found that both reflection loss (RL) and shielding effectiveness (SE) depend on the filler content. The effect of fillers mixing ratio were investigated too. Results showed samples with higher MWNT content exhibits better shielding effectiveness, while samples with higher NiZn ferrite achieved better reflection loss. The microwave absorbing properties of these samples can be adjusted according to desired application.

Abstract: Blend-based polymer electrolytes composed of PVDF-HFP/MG-49 (70/30) and LiClO4 as lithium salt has been studied. Solution casting method was applied to prepare the polymer electrolyte. Electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the electrolyte films. The maximum value of 2.51×10ˉ6 S cm-1 was obtained at ambient temperature for the 30 wt. % of LiClO4 and the conductivity increased to 1.10×10ˉ3 S cm-1 by increasing the temperature up to 383 K. FTIR spectra demonstrated that complexation occurred between the polymers and lithium salt.

Abstract: In this study, paper sludge ash, a waste from pulp and paper industry was used as a filler in fabricating Plaster of Paris/paper sludge ash composites. Various percentage of paper sludge ash was used, namely 1wt.%, 3wt.%, 5wt.% and 7wt.%. The effect of paper sludge ash on the compressive strength of the Plaster of Paris was studied. The mixed powder of paper sludge ash and Plaster of Paris were form into a 6 mm diameter and 12 mm height cylindrical samples. The composites were characterized theirs density where it shows that the density decreased as the amount of paper sludge ash increased. The compressive strength of the composites also decreased from 11.67 MPa without paper sludge ash addition to 0.50 MPa at 7wt.% paper sludge ash. However, the requirement of strength for Plaster of Paris in industry is between 8.96 MPa to 20.68 MPa. From the SEM observation, sample contain higher percentage of paper sludge ash exhibited more porosity. Therefore with the addition of 1wt.% of paper sludge ash into Plaster of Paris can be a promising construction material.

Abstract: 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

Abstract: The effect of plasticizer (PC) on the conductivity and chemical interaction of polymer electrolyte of MG49–PC–LiClO4–TiO2 has been investigated. The electrolyte films were successfully prepared by solution casting technique. Alternating current electrochemical impedance spectroscopy was employed to investigate the ionic conductivity of the electrolyte films at 25 °C, and the analysis showed that the addition of propylene carbonate (PC) plasticizer has increased the ionic conductivity of the electrolyte up to its optimum level. The highest conductivity of 2.54×10−4 Scm−1 was obtained at 30 wt.% of PC. Fourier transform infrared spectroscopy measurement was employed to study the interactions between lithium ions and oxygen atoms that occurred at carbonyl (C=O) and ether (C-O-C) groups. XRD pattern showed that the crystallinity phase was reduced at the highest conductivity.