Theses & Dissertations
Permanent URI for this collection
Browse
Recent Submissions
1 - 5 of 285
-
PublicationMg-A1 hydrotalcite supported ionic liquid polyvinylidene fluoride -CO- hexafluoropropylene membranes for CO₂ permeation(Universiti Malaysia Perlis (UniMAP), 2017)Membrane technology has gained great importance in carbon dioxide separation processes. Membrane processes are simple, energy-efficient, which can be economical in comparison to traditional separation technologies. In this research Polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) membranes with controlled asymmetric microstructure and functionalized with room temperature ionic liquid (RTIL) are used for the separation of C0₂ from a gas stream. Polymeric membranes are fabricated from PVDF-HFP and polyethylene glycol (PEG) using the phase inversion method. To produce the optimum polymeric membrane, several parameters that influence the membrane structure and morphology such as concentration of polymer (16-20 wfl/o of PVDF-HFP), type of solvent, organic additives (0- 10 wt% PEG), evaporation time (0- 180 second) and coagulation bath medium (0-75 wt% ethanol concentration) during phase inversion were studied. The membranes were characterized by Scanning Electron Microscopy (SEM) Fourier Transform Infrared (FTIR) Spectroscopy, Surface Area Analysis (BET), Viscosity and Porosity Analysis, and X-ray diffractometer (XRD). In the current research an experimental set-up was designed and build, which was capable of measuring gas permeability through various types of polymer membranes, under a wide range of operating conditions. Pure single gas C0₂ and N₂ were used to study the efficiency of the membrane in permeance and permselectivity in membrane permeation test. The polymer membranes have been modified with a selective layer made from polyethylene glycol (PEG), Ionic liquid 1-butyl-3-methylimidazolium bis (trifluoromethyl) sulfonyl imide, [bmim +][NTf2 -] and Hydrotalcite (HT). A membrane configuration of PVDF-HFP/PEG 17/ 3 wt% membrane (F3) and 35 wt% ethanol concentrations was found to give good permeance and permselectivity being 2970 GPU and 2.72 respectively. This membrane was improved by adding 25.55 wt% RTIL to prepare the supported ionic liquid membrane (SILM) using vacuum immobilization technique (F3-IL) and the result showed a little decrease in permeance (2500 GPU) but a clear increase in permselectivity (19.26). Also, adding a thin selective layer to the membrane (F3-IL-1.0 HT) resulted in a significant increase in permeance (3640 GPU) without any loss in permselectivity (19.11 ).
4 3 -
PublicationSynergistic effect of bioactive compounds of polyherbal fractions of Clinacanthus Nutans and Elephantopus Scaber in the treatment of wound(Universiti Malaysia Perlis (UniMAP), 2017)Modern healthcare system recognizes herbal medicine as a form of alternative medicine. Everyone in their life span experiences a different kind of wound. Clinacanthus nutans and Elephantopus scaber are well known traditional wound healing herbs. The present research work develops a new polyherbal formulation from the leaves of Clinacanthus nutans and Elephantopus scaber in the treatment of wound. Furthermore, bioactive compounds from different fractions were identified by using chromatography and spectroscopic method. The water soluble was further fractioned to isolate bioactive compounds. The herbal combination of Elephantopus scaber and Clinacanthus nutans were evaluated as an in-vitro antioxidant activity containing equal amount of both medicinal herb with their individual herbal activity followed by fractionation of polyherbal formulation for in-vivo wound healing activities. Antioxidant activity was performed in vitro by DPPH radical scavenging antioxidant activity followed by in-vivo wound healing activities using different wound model. The leaves of Clinacanthus nutans and Elephantopus scaber were extracted with 50% ethanol (EtOH) and separated using silica gel, Sephadex LH-20 to isolate the pure compounds. 2-(aminomethylsulfinyl)-N-hydroxyacetamide was the proposed compound isolated from aqueous fraction of the polyherbal formulation. The characteristics of the isolated compounds were achieved using Infrared spectroscopy (IR) and LCMS scan on aqueous fraction. The result showed that Elephantopus scaber crude extract on the basis of ECso performs a much faster action but with less % inhibition as compared to the combination of the new polyherbal formulation of crude extract. The polyherbal formulation has the highest % inhibition (89.49%) at the same dose as compared to individual Elephantopus scaber (87.66%). Comparison among all crude and fractions of new polyherbal formulation, it was found that the ethyl acetate fraction of polyherbal formulation has the fastest activity, ECso 14.83 J.tg/ml, with inhibition of 89.28%. Furthermore, during evaluation of wound contraction on excision and incision wound model, ethyl acetate fraction possess highest activity with (P < 0.001) and (P < 0.0001) respectively. During burn wound model, aqueous fraction (P < 0.001) possesses highest activity followed by an ethyl acetate fraction (P < 0.0001). Liquid chromatography-Mass spectrometry (LCMS) analysis identifies the presence of several flavonoid-based compounds that work synergistically with other bioactive compounds. These bioactive compounds were further confirmed by liquid chromatography-electrospray ionizationtandem mass spectrometry (LC-ESI-MS/MS). The prescence of bioactive compounds such as apigenin, luteolin, b-sitosterol, 3'-hydroxy-5,6,7,4'-tetra methoxy flavone, quercetin, vanillin, gallic acid, benzoic acid and rutin were confirmed by using High performance liquid chromatography. In conclusion, flavonoid increases the antioxidant activity that surge the rate of wound contraction and work synergistically with other bioactive compounds.
-
PublicationEffect of nanosepiolite and nanosilica content, polyethylene-grafted-maleic anhydride and irganox 1010 on tensile and morphological of low density polyethylene nanocomposites(Universiti Malaysia Perlis (UniMAP), 2017)Nanocomposites of thermoplastic blend of low density polyethylene (LDPE) filled with nanosepiolite and nanosilica was investigated. All of the test samples were prepared using Brabender Internal Mixer Plastograph EC Plus (Duisberg, Germany) at 160°C, speed of 50 rpm and moulded using compression at temperature of I60°C. Results showed that the nanosepiolite filled composites gave better tensile properties than nanosilica filled composites at same filler loading. The adhesion between filler and matrix was improved by using MAPE as a compatibilizer at 3 phr content. All the properties were improved for both nanocomposites. The addition of antioxidant into the nanocomposites showed that the lowest content of antioxidant at 1 phr gave higher tensile strength and Young's modulus compared to 3 phr and 5 phr. The effect of thermal ageing was also investigated by exposing the nanocomposites in air circulated oven at 70°C for 72 hours. The nanocomposites were found to show better properties than the control nanocomposites when antioxidant were added to the nanocomposite system and supported by S ~ M morphology and FTIR analysis.
8 1 -
PublicationCharacterization and properties of low linear density polyethylene / Typha Latifolia (LLDPE / Typha Latifolia) composites(Universiti Malaysia Perlis (UniMAP), 2016)Fabricating polymer (low linear density polyethylene) with a natural fiber such as Typha Latifo/ia, will provide a new opportunities to the manufacture a green plastic products. In this study, three objectives have been carried out such as characterization of the Typha Latifolia, effect of different sizes and loading and influences of NaOH modification on fiber towards LLDPE/Typha Latifolia composite. The experimental was prepared by using extruder machine with parameter of 150°C- 160°C temperature and speed of 70rpm. The characterization such as tensile properties (tensile strength, elongation at break and Young modulus), X-ray fluorescence spectrometry (XRF), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) on composites were determined. Results indicated that the distribution of the Fine size Typha Latifolia was very prominent between 99.19 J.!In and 447.37J.!m on particle size analyzer while the coarse in between 1-4 mm. XRF results detected the calcium oxalate monohydrate and potassium, which is accumulated between ultimate Typha Latifolia fibers. The incorporation of Typha Latifolia into LLDPE found that the reduction on tensile strength and elongation at break except for Young's modulus. However, the fine size of Typha Latifolia shows the high value on properties compared with Coarse size at all loading ratios of LLDPE/Typha Latifo/ia composites. The addition of 15% fine size Typha Latifolia with 3% concentration of NaOH treatment demonstrated the optimum value in tensile strength and elongation at break of LLDPE/Typha Latifolia composites excluding young modulus. It was believed that the hydroxide sodium NaOH on fiber thus improved the tensile properties of the composites. The observation on the morphology of the composites proved that the treatment improved the adhesion between fibers and matrix.
1 11 -
PublicationPembangunan teknik keupayaan cas sifar untuk aplikasi perlindungan kakisan(Universiti Malaysia Perlis (UniMAP), 2016)This study aims to modify the practice of using over-voltage concept of polarization process in cathodic protection to the potential of zero charges (Epzc) as a new technique of corrosion prevention. At Epzc, a metal surface is not in contact with an aqueous solution due to the absence of electrical charge and no electrostatic attraction. A chemical adsorption caused by oxidation reaction does not occur at Epzc· The removal of electrical charges at the electrode-electrolyte interface leads the desorption of ionic charges which causes the metal surface suffers no longer a corrosion reaction due to the absence of a charge transfers. The determination of Epzc is carried out by measuring the border line of adsorption and desorption of charged ions on the metal surface by the intersected inducing polarization methods on the intermediate rod. The experimental Epzc value ( -703 m V vs SCE) is more negative than the corrosion potential (Ecorr = -701 mV vs SCE) shows the immersed metal in 3.5% NaCl solution have an excessive positive charge. Therefore, the negative charge is required to eliminate or neutralize the positive charges to bring the metal surface to Epzc· The charge removal is a discharging of double-layer process on the metal-solution interface. It is carried out by supplying electrons to the extent necessary just to eliminate the positive charges on the metal surface by using potentiostat. The discharging was perfmmed by means of voltage scan method around Epzc (Epzc scan) with an ideal magnitude at about 2 m V, which is slightly negative than corrosion potential (Ecorr) at the lowest rate (1.0 x 10-2 mV/ min). The plot of current density versus time takes about 100 hours to displays a capacitor discharging curve profile. The current requirement for corrosion protection at Epzc is not critical after a 100 hour period. The planned interval immersion tests on reactive Mg metals clearly prove that corrosion protection at Epzc is succeed and their corrosion protection efficiency is between 93-96% in 3.5 % NaCl solution.