Abstract: Geopolymers are fast setting binder materials possessing strength comparable with Portland cement. In this study solidification and bonding behavior of sodium hydroxide activated class F fly ash geopolymers were determined. Solidification was determined using Vicat apparatus and bonding behavior study was carried out using Fourier transform infrared spectroscopy (FTIR). The decrease in solidification time from 105 minutes to 90 minutes was observed when Na/Al ratio increased from 1 to 1.4. By changing liquid to solid (L/S) ratio from 0.154 to 0.231 initial and final setting times found to increase. FTIR results showed main peaks at 1000 cm-1 and 1432 cm-1 due to asymmetric stretching of Al-O/ Si-O bonds.
Abstract: Cloud points at different polymer concentrations were obtained by the simple titration method and compared with the numerically calculated theoretical binodal curves for Polycarbonate/Dimethylacetamide/Water (PC/DMAc/Water) and Polycarbonate/N-Methyl-2-pyrrolidone/Water (PC/NMP/Water). The interaction parameters for solvent polymer and nonsolvent polymer were obtained from Hansen's solubility parameters. The cloud points determined were found to be in close agreement with the theoretical binodal curve calculated. Coagulation values for different solvents such as Dichloromethane (DCM), Dimethylacetamide (DMAc), N-Methyl-2-pyrrolidone (NMP) and Tetrahydrofuran (THF) were also determined and the results were plotted in a ternary diagram to realize the effect of interaction parameters on the coagulation values. The higher the mutual affinity of solvent to polymer (low χ23), the faster is the liquid-liquid demixing rate to occur. For DCM solvent, fastest demixing rate was exhibited and lowest for the THF.
Abstract: Si-MCM-41 was functionalized with 10-50wt% loading of Diethanolamine (DEA) using impregnation method and characterized for their physicochemical properties using XRD, FTIR and HRTEM. Results show that the intensity of the diffraction peaks attributed to the finger-prints of Si-MCM-41 decreases with increased loading of DEA. The peaks assign to (110), (200), and (210) planes start to disappear at DEA loading as low as 10wt%. FTIR spectra of DEA-Si-MCM-41 show presence of –N-H and –C-H peaks which confirms the functionalization of Si-MCM-41 with DEA. HRTEM micrographs of all samples clearly show the uniform hexagonal pore arrangement which proved the structural integrity of Si-MCM-41 even after functionalization with 50wt%.
Abstract: Phenolic compound from Nephelium lappaceum leaves was investigated using Gallic acid as a precursor. The compound was extracted from the leaves in 50, 70, 90 and 100% methanol solvent (10:1 w/v ratio) at 60oC and 75oC. Based on HPLC analyses, the optimum of 71.4 mg/g of GA was extracted from green leaves in 50% methanol at 60oC with FRAP value of 0.23 mM/500 mg. FRAP result showed that the effect of metal chelating activity was significantly increased with increasing extract concentration and GA was the dominant phytochemicals in the NL giving significant antioxidant activity.
Abstract: CO2 solubility in aqueous potassium carbonate promoted with amino acid (glycine) was measured at temperatures (303.15, 313.15, and 333.15) K over the partial pressure range from 200 to 1000 kPa. The solubility of CO2 is reported as the loading capacity of the CO2 in the solvent, defined as (moles of CO2 per mole of solvent). It was found that the loading capacity of the CO2 increases by increasing the partial pressure of the CO2, whereas, it reduces with increase in temperature. CO2 loading capacity in aqueous potassium carbonate (PC) promoted with glycine (GLY) was also compared with different solvents, which shows that the new solvent blend is considerably better than various solvents.
Abstract: Four samples of covalent organic framework-1 (COF-1) assigned as S1 to S4 were prepared by varying the initial mass of 1,4-benzene diboronic acid (BDBA) used and heating condition. The samples were physically characterized using Brunauer–Emmett–Teller (BET) surface area analysis and FESEM analysis. The BET surface area value showed an increasing trend with increasing mass of BDBA used. The highest achievable BET surface area is recorded by COF-1 (S3) with a value of 107.9 m2/g. The low surface area obtained is likely due to the distribution of particles with large pore sizes. This is confirmed by the Field Emission Scanning Electron Microscopy (FESEM) images which correlate well with the surface area obtained. The presence of dendrites phase within the COF-1 structure also indicates incomplete formation of a crystalline structure, hence contributed to the low surface area achieved. It was also found that the use of ramping heating did not significantly influence the formation of COF-1 crystalline structure which promotes the surface area.
Abstract: Effect of addition different polymers and fillers with electron beam irradiation on changes of physical, electrical and flammability properties of low density polyethylene (LDPE) / trimethylol propane trimethylacrylate (TMPTMA) / Irganox/ zinc borate (ZB) have been investigated. Results of measured gel content (GC), tensile strength (TS), elongation at break (EL), hot set (HS) tests, melt index (MFI), dielectric strength (DS), volume resistivity (VR), flammability and limiting oxygen index (LOI) have confirmed positive effects of adding maleic anhydride grafted LDPE (LDPEgMAH), ethylene vinyl acetate (EVA) and CS whereas effect of ATH to blends drastically had negative effects on improvement of physical properties of blends. Meanwhile, presence of TMPTMA and enhancing irradiation could improve properties seriously. Keywords Halogen free; polymers; irradiation; wires and cables
Abstract: This paper deals with the decentralized control design for ethanol fermentation by Zymomonas mobilis. Extractive fermentation has been proposed to improve the ethanol yield and productivity due to product inhibition. The complexity of biological systems and significant process variability can always lead to ineffective control system performance. In this paper, a 2x2 and 3x3 multi-scale control systems have been proposed. It is shown that the PID control design based on the multi-scale control scheme is effective for complex high-order systems.
Abstract: Fly ash has a high potential to be converted into geopolymeric material due to its abundant supplies and low cost. However, large particle size of the fly ash caused low reactivity which results in low properties of the end product. The improvement on the fly ash properties by mechanical activation allows it as a new possible raw material in wider application besides solving the low reactivity issue which hindered its range of utilization. In this study, fly ash was mechanically activated by high energy planetary ball mill for 1 hour at different speed, ranging from 100 to 350 rpm and with varied ball to powder ratio (2:1, 3:1 and 4:1). The effects towards its particle size, specific surface area and morphology were determined by particle size analyzer and SEM. It was observed that, increasing of speed to 350 rpm and 4:1 ball to powder ratio (BPR) results in finest size of fly ash where at d (0.1), d (0.5) and d (0.9) the sizes were 1.861, 6.765 and 17.065μm respectively and largest surface specific area (1.46 m2/g).