International Research Conference of UWU-2021
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Item Effect of Residual Diammonium Hydrogen Phosphate Content on Properties of Natural Rubber Centrifuged Latex(Uva Wellassa University of Sri Lanka, 2021) Siriwardhana, M.W.H.N.M.; Attanayake, A.; Lochana, E.A.L.; Senevirathna, A.M.W.K.Natural rubber particle, a polyisoprene core is surrounded by a shell of non-rubber components, proteins and phospholipids. Natural PO43- are added to ammonia preserved latex due to the hydrolysis of phospholipid layer around the rubber particle. Although this process contributes to the stability of the latex this could produce a waste sludge; a precipitate of magnesium with phosphate. In centrifuged latex (CL) manufacturing process PO43- are added as diammonium hydrogen phosphate (DAHP) before centrifugation in order to remove residual Mg2+ present in field latex to the level of 80-100 ppm. In most cases, added DAHP will leave excess PO43- in latex as most manufacturers added it without estimating the remaining Mg2+ present in latex. It results in a high amount of PO43- in latex as a considerable amount of PO43- are released from the natural process of hydrolysis with storage time. This study aimed to determine the variation of residual PO43- content of CL with storage time and its ultimate effect on latex property development. A series of centrifuged latex samples were prepared by adding 0 g (control sample), 3 g, 6 g, 9 g, 12 g, and 15 g of 15% DAHP. Changes of the latex characteristics such as mechanical (MST) and chemical stability time (CST), PO43- and Mg2+ concentration, viscosity were determined with time. All the testing were carried out according to ISO procedures. High ammonia preserved CL showed a considerable amount of natural PO43- of about 300-200 ppm with storage time. The PO43- content of latex is not a stable amount and showed several fluctuations with time due to several chemical reactions within the latex sample. The excess amount of PO43- in the latex leads to a decrease in viscosity and stability of latex due to colloidal destabilization. The control sample showed the highest MST (315 seconds) and CST (97 seconds) with storage time than other samples revealing that there is no need for the addition of DAHP if the Mg2+ content of field latex is below 100 ppm in manufacturing CL. Keywords: Latex; Diammonium; Phosphate; Magnesium; Destabilization; ColloidalItem A Comparative Study on Degradability of NBR and NR Latex Gloves(Uva Wellassa University of Sri Lanka, 2021) Manukularathne, W.G.P.D; Sandamali, P.K.N.N; Siriwardena, S.; Lochana, E.A.L.; Senevirathna, A.M.W.K.Natural rubber (NR) and Nitrile rubber (NBR) gloves are two main types of latex gloves used in the personal protective equipment market. In the face of an abrupt increase in the demand and usage of these gloves due to the present Covid-19 pandemic, degradation of these gloves after usage may create an environmental threat. Therefore, a study was conducted to compare the degradable behavior of these products. Both glove types were treated under thermal and hydrothermal, and UV radiation environments. Untreated samples were used as the control. Under thermal, hydrothermal and photo- oxidative treatments, an increase of the swelling index of untreated NR gloves (65.2%) increased by 38.23%, 14.69% and 7.17%, respectively while NBR gloves showed a percentage swelling index increment of 14.52%, 15.56% and 12.12% with compered to the percentage of the swelling index of the untreated sample (28.77%) in the same order of treatments. The average tensile strength of NR was decreased from 16.89 to 15.67, 11.19, and 15.63 MPa while for NBR it decreased from 28.06 to 24.35, 23.93 and 20.56 MPa after the thermal, hydrothermal and UV exposure, respectively. Hydrothermally treated NR gloves showed new peaks suspected as hydroxyl groups and carbon- carbon triple bonds. Spectra of thermally and hydrothermally treated NBR showed identical loss of the peak responsible for the cyanide group. TGA analysis showed that the initial decomposition temperature of NR has reduced from 365.42 ̊C to 364.95 ̊C, 360.63 ̊C and 365.27 ̊C, respectively after the thermal, hydrothermal and UV treatments. NBR gloves also showed the same trend except for hydrothermal treatment where an increase in initial decomposition temperature was recorded. Overall, hydrothermal treatment was the best degradation method for NR gloves among candidates while exposure to UV radiation exhibited the highest degradation potential for NBR gloves. It was also found that removal of cyanide group when NBR gloves were subjected to hydrothermal degradation. Keywords: Fourier transform infrared spectroscopy; Natural rubber; Nitrile Butadiene rubber; Thermo gravimetric analysis; UltravioletItem Effect of Fiber Size on Properties of Oil Palm Fiber Waste Filled Natural Rubber Composites(Uva Wellassa University of Sri Lanka, 2021) Madushika, T.G.K.H.; Weerasinghe, U.A.; Edirisinghe, D.G.; Lochana, E.A.L.; Senevirathna, A.M.W.K.The twenty-first century has witnessed remarkable achievements in the rubber industry regarding green technology through the development of natural fiber based rubber composites. A wide variety of natural fibers extracted from coconut, palmyra and banana has been used as fillers in the development of natural rubber (NR) based green composites, most importantly to reduce environmental pollution caused by hazardous powdered fillers and to enhance reinforcement. Oil palm fiber (OPF) is hard, tough and has the potential to reinforce the rubber matrix. Mesocarp part of OPF, which generates as a waste material of palm oil processing mills was used as a filler in this study. The objective was to investigate the effect of size of OPF on cure, physico-mechanical, water absorption and ageing properties of NR composites. A chemical treatment was conducted to reduce fiber size and to improve physico-mechanical properties. Chemical processing with sodium hydroxide, bleaching with sodium chlorate and oxalic acid were conducted to remove residual oil and reduce fiber size. A series of NR composites were prepared with 2 phr OPF by varying its size from 250 μm to below 50 μm. The NR composite prepared without OPF, but with 2 phr of carbon black was considered as the control. Although an increase in properties was expected with the reduction of fiber size, no significant increase was observed. Nevertheless, results showed the highest values for the NR composite prepared with OPF in the size range 125-175 μm in regard to modulus at 300% elongation, tensile strength, hardness, resilience and an average value for water absorption. This revealed even dispersion of OPF in the rubber matrix of the above composite and the results were in agreement with crosslink density indicated by the delta cure value. There was no decrease in tensile modulus and strength after ageing, which indicates high retention of these properties. Overall, results revealed that carbon black in NR composites could be replaced with OPF to manufacture rubber products requiring hardness ranging from 29-36 Shore A. Keywords: Oil palm fiber; Natural fillers; Natural rubber; Cure characteristics; Physico-mechanical propertiesItem Development of a High Abrasion Resistance Shoe Sole Incorporating Four Different Silica Grades(Uva Wellassa University of Sri Lanka, 2021) Ruchikala, R.M.; Withanage, N.S.; Vithanachchi, J.Silica used as active reinforcing filler to improve high abrasion resistance in Rubber. In this study, the effect of four different silica grades (silica MP BET 161-190, silica powder newsil micro peral, silica 355GR and silica BET higher grade) on the abrasion resistance and other properties of the shoe sole have been studied. In this study type of silica grades was changed while keeping all the other ingredients and their amounts constant. The abrasion resistance was determined using DIN 53516 test method and the hardness, specific gravity, tensile strength and elongation at break were determined by following the respective ISO and ASTM standards. The results of the study showed that all four silica grades incorporated shoe soles have achieved acceptable abrasion resistance values. Achieved abrasion resistance value for shoe sole is maximum 350mm3. However, silica MP BET 161-190 has 289 mm3 which is also a quite higher abrasion resistance with a minimum loss of rubber in abrasion compared to other three silica grades. When considering the effect of silica grade on the physical properties of rubber compound, both silica MP BET 161-190 and 355GR grades showed acceptable values for all tested hardness, specific gravity, tensile strength and elongation at break of silica MP BET 161-190 grade incorporate sample were 48 IRHD, 1.088,17 MPa and 676% respectively. While silica 355GR incorporated sample were 51 IRHD, 17.1MPa and 631% respectively. However, both silica powder newsil micro peral and silica BET higher grade incorporated samples showed poor performance for the tested physical properties. Therefore, it can be concluded that, silica MP BET 161-190 is better performing as an active reinforcing filler with the highest abrasion resistance and a minimum loss of rubber in abrasion compared to other three silica grades. Keywords: Abrasion resistance; Physical properties; Shoe sole; Silica gradesItem Effect of 4-tertbutyl pyridine and guanidinium thiocyanate Co-Additives on Performance of Dye-Sensitized Solar Cells Fabricated with Non-Volatile Liquid Electrolyte(Uva Wellassa University of Sri Lanka, 2021) Umair, K.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.; Kumari, J.M.K.W.Dye-sensitized solar cells (DSSCs) are emerging as potential candidates to substitute for expensive silicon solar cells because of reasonably high efficiency, easy fabrication method, lower production cost and transparency. Electrolyte modifications of DSSC are an easy way to enhance the photovoltaic performance. The conventional liquid electrolyte system is composed of iodide/triiodide single salt in the volatile, acetonitrile solvent. In this work, the non-volatile ethylene carbonate (EC) and propylene carbonate (PC) were used with tetrapropyl ammonium iodide (Pr4NI) salt to prepare the reference electrolyte. The effect of the co- additives 4-tert butylpyridine (TBP) and Guanidinium thiocyanate (GuSCN) on the photovoltaic performance of DSSCs was also studied. The addition of TBP as an additive into the iodide electrolyte system increased the photovoltage (VOC) by 13.8%, but it reduced the photocurrent density (JSC) by 7.2%. However, the JSC was increased by about 8.7% by the addition of GuSCN as the additive. The addition of the combination of TBP and GuSCN binary additives in the optimized ratio of 65:35 enhanced the cell efficiency from 5.63% to 6.83%. The overall efficiency enhancement has been explained by the shifting of the conduction energy band edge of TiO2 due to the adsorption of species from the two co-additives by TiO2 leading to the enhancement of both, the photocurrent density as well as the photovoltage. TBP improves the VOC by a negative shift of the band-edge and also prevents the electron recombination to I3- due to the blocking effect on the dye-absent active site of the TiO2 surface. The addition of GuSCN to TBP-added electrolyte restored the JSC by the positive shift of the band-edge. The net effect is to increase the overall performance of DSSCs due to the synergistic effect of the two co-additives. Keywords: Photovoltaic effect; Co-additives; Band-edge shift; Non-volatile; VOC improverItem Enhanced Photovoltaic Properties of Cadmium Sulfide Quantum Dot Sensitized TiO2 Solar Cells with Novel SnO2 Based Counter Electrode(Uva Wellassa University of Sri Lanka, 2021) Sandamali, W.I.; Senadeera, G.K.R.; Dissanayake, M.A.K.L.; Jaseetharan, T.; Kumari, J.M.K.W.; Umair, K.; Perera, V.P.S.; Rajendra, J.C.N.; Karthikeyan, N.Quantum dot sensitized solar cells (QDSSCs) have gained increased attention due to the unique properties of the semiconductor quantum dots (QDs), as light captivating materials. QDs facilitates multiple exciton generation, tunable bandgaps, high absorption coefficient, and low power consumption. Many studies have been carried out towards producing affordable QDSSCs with high power conversion efficiencies, utilizing these properties. As a critical component of QDSSCs, counter electrodes hold significant importance among these studies. Platinum (Pt), a widely used counter electrode with QDSSCs, is being disfavored due to high cost, diminishing material supply, and reduced catalytic activity, when used with polysulfide electrolyte which is the most common electrolyte for QDSSCs, due to surface, adsorbed sulphur. Therefore, substantial investigations have been carried out in searching for an alternative, affordable and effective counter electrode in these devices. Among the suitable materials, tin oxide (SnO2), a wide bandgap semiconductor, has become a promising candidate for counter electrode due to its high chemical stability, high electron mobility, low cost and environmentally friendly nature. In this study, counter electrodes were fabricated by depositing SnO2 films on fluorine-doped tin oxide (FTO) glass substrates by using a simple spray pyrolysis technique. These counter electrodes were characterized by scanning electron microscopic and Raman techniques. Photovoltaic properties of CdS quantum dots sensitized TiO2 solar cells with polysulfide electrolyte were tested by using this novel counter electrode. QDSSCs fabricated with optimized SnO2 counter electrode showed 1.47% power conversion efficiency under the illumination of 100 mW cm-2, whereas the devices fabricated with conventional Pt coated counter electrodes showed 1.08% under the same conditions. Therefore, about 36% enhancement in power conversion efficiency could be obtained by employing this novel low-cost counter electrode in these QDSSCs. Keywords: Counter electrode; SnO2; CdS; Quantum dot sensitized solar cellItem Green Synthesis of Zn Nanoparticle (ZnO NPs) Using Palmyrah Resource and Evaluation of Its Antimicrobial Property(Uva Wellassa University of Sri Lanka, 2021) Nirosha, A.U.; Vinujan, S.; Lochana, E.A.L.; Arachchige, M.P.M.; Srivijeindran, S.Borassus flabellifer is a tree found in the tropical belt of Sri Lanka and almost all parts of the tree can be used for various purposes like food, medicine, and others. Mostly, the leaf has been used to make handicraft items and is popularly known for this only but other than this, there is a potential for the leaf being used for various purposes. Only very few studies were conducted to evidence the medicinal importance of palmyrah leaf. The aim of this work is associated with plant-mediated nano- particle synthesis through developing low-cost, eco-friendly processing using palmyrah leaf extract and zinc sulphate and sodium hydroxide as precursor solution. The artificial synthesis of ZnO is assisted by chemical processing and leaving several hazardous effects on the world. The nanoparticles synthesized were characterized using X-ray diffraction analysis and the antibacterial activity was evaluated by the agar well diffusion method. The X-ray diffraction (XRD) spectrometer was used to determine the crystalline size of nanoparticles synthesized as 20 ± 6 nm at the wavelength of 517 nm. Antimicrobial activity for two different concentrations of ZnO nanoparticles (50 and 100 mg/ml) was studied for Escherichia coli. A significant inhibition activity was observed for the tested two concentrations and the maximum activity (18 mm) was observed from the highest concentration. An attempt is employed for the synthesis of ZnO nanoparticles using leaf extract of Borassus flabellifer in an environmentally friendly manner. In this green nano-particle synthesis process, palmyrah leaf extract has functioned as a reducing and capping agent. Green aspects of ZnO nanoparticle synthesis could be recommended as an alternative to high thermal chemical processing. Further characterization for associated phytochemical compounds and any toxic factor will assist to incorporate this nanoparticle for developing any value-added product from palmyrah in the future. Keywords: Borassus flabellifer; ZnO nanoparticle; XRD analysis; Antibacterial activityItem Comparative Study of Catalytic Reduction of Methylene Blue by Green Synthesized Copper Nanoparticles Using Syzygium cumini Leaves Extract(Uva Wellassa University of Sri Lanka, 2021) Sivirathne, S.M.S.W.; Senevirathne, S.A.; Jayaratna, N.B.Green synthesis using plant extracts is considered as an efficient, eco-friendly and inexpensive approach in metal nanoparticle synthesis. Copper nanoparticles are well known as catalysts in many organic reactions. The present study focuses on the green synthesis of heat and sunlight-induced copper nanoparticles using Syzygium cumini leaves aqueous extract as the source of reducing and capping agents. Synthesized nanoparticles were used to investigate and compare the catalytic effectiveness in the reduction reaction of Methylene Blue. The leaves extract was prepared by treating the leaves with distilled water at 50 °C for 1 hour. Copper nanoparticles were synthesized by mixing a known copper sulphate solution with leaves extract at a volume ratio of 5:3 followed by either heating (4 hours at 50 °C) or irradiating the mixture to sunlight for 4 hours. The synthesis of copper nanoparticles was initially recognized by the colour change of the extract solutions from pale yellow to dark brown. The formation of heat and sunlight derived copper nanoparticles were confirmed by UV-Visible peak maxima at 335 nm and 333 nm, respectively. Peak positions of Fourier transform infrared spectra of synthesized copper nanoparticles have revealed the activity of biomolecules as reducing and capping agents. Catalytic activities of synthesized copper nanoparticles were investigated using the reduction reaction of aqueous Methylene blue to Leucomethylene blue in the presence of excess NaBH4 as a model reaction. The reaction progress was monitored by UV– Visible spectrophotometry at room temperature. The apparent rate constants of the reaction in the presence of heat and sunlight derived copper nanoparticle catalysts were 51.1×10-3 min-1 and 32.6×10-3 min-1 respectively. The apparent rate constant of the reaction in the absence of copper nanoparticle catalyst was 8.1×10-3 min-1. The study confirms the catalytic activity of Syzygium cumini leaves derived copper nanoparticles while heat-induced copper nanoparticles showed 56% greater catalytic activity compared to sunlight-induced copper nanoparticles. Further characterization of nanoparticles and optimization of the biosynthesis parameters are needed to be performed. Keywords: Green synthesis; Dye degradation; Sunlight irradiation; SustainabilityItem The Effect of Bis-(3-triethoxysilylpropyl)-Tetrasulfane and Polyethylene Glycol on the Properties of Natural Rubber/ Mica Composites(Uva Wellassa University of Sri Lanka, 2021) Edirisinghe, E.D.S.; Somarathna, Y.R.; Withanage, N.S.; Dhanukamalee, H.M.H.; Samarasinghe, I.H.K.; Siriwardena, S.The bis-(3-triethoxysilylpropyl)-tetrasulfane (Si69) is widely applied as a coupling agent to rubber- filler interactions in silica filled rubber composites. In this study, the effect of bis-(3- triethoxysilylpropyl)-tetrasulfane (Si69) and polyethylene glycol (PEG) on the properties of natural rubber (NR)/mica composites has been studied. The mica loading and the total weigh of Si69/PEG were kept constant at 30 phr and 2 phr, respectively. A composite free from Si69/PEG (SP00) was used as the control, while ratios of the above chemicals (Si69: PEG) were varied as 1:0, 0:1 and 1:1 in the other composites. These three systems were denoted SP10, SP01 and SP11, respectively. Curing characteristics, physico-mechanical properties and thermal degradation of NR/mica composites were investigated. The maximum cure time (Tc90) and scorch time (TS2) were exhibited in the SP10 compound. However, introduction of PEG into the system with Si69 in SP11 composite yield a reduction in Tc90 and TS2, which were comparable with the control (SP00). Maximum tensile strength and elongation at break were observed in Si69 treated NR/mica composite (SP10). This could be attributed to the improved rubber-filler interactions caused by incorporation of higher amounts of Si69 (2 phr). Further, the composite treated with both Si69 and PEG (SP11) with 1 phr each, has shown the second highest tensile strength among candidate composites. However, the enhanced moduli values at 100%, 300% and 500% elongation indicated better rubber-filler interactions in SP11 composite than SP10. The same reason may have resulted the highest hardness and resilience values in SP11 composite. The thermogravimetric analysis indicated that the application of Si69 and/or PEG have no significant impact on the thermal degradability of NR/mica composites. It was also found that SP01 exhibited the highest swelling ratio among all samples. Therefore, overall results indicated that PEG/Si69 treated system (SP11) could be employed more effectively than individual use of Si69 and PEG to optimize the cure characteristics, while improving the physico-mechancial properties of NR/mica composites. Keywords: Mica; Natural rubber composites; Polyethylene glycol; Coupling agent; Rubber-filler interactionsItem Utilization of Sugarcane Bagasse Ash as a Partial Replacement of Fine Aggregate in Grade 45 Concrete(Uva Wellassa University of Sri Lanka, 2021) Himasara, P.A.H.S.; Thannahena, T.H.D.D.; Naveendra, J.A.L.; Senarathne, K.G.C.Nowadays, many investigations focus on ways of utilizing industrial or agricultural wastes as a replacement for the construction industry. In addition to the financial benefits in this regard, such materials may also lead to sustainable products and a pollution-free environment. Sugarcane bagasse ash is one such siliceous and aluminous waste generated in the sugar refining industry apart from ethanol. In this study, fine aggregates in a concrete mixture were partially replaced by untreated sugarcane bagasse ash under different weight percentages: 0%, 10%, 20% and 30%. The untreated bagasse ash was also used as another raw material in the concrete mix apart from other raw materials: fine aggregates, coarse aggregates, cement and water. The compressive strength measured at 28 days was considered to determine the optimum ash content for the concrete mix. In this optimum range, the highest value range for compressive strength is found. Accordingly, the optimum ash content should be between 0% - 10%, if sugarcane bagasse is used as a partial replacement to fine aggregates. However, when added in addition to the existing materials (without partial replacement), the outcomes for the compressive strength have not found to be favourable. The compressive strength is comparatively low in this case compared to the full replacement scenario. This study thus concludes that high strength concrete can be made by utilizing sugarcane bagasse ash as a partial replacement of fine aggregate. Keywords: Compressive strength; Sugarcane bagasse ash; Sugarcane bagasse; Agricultural wasteItem Preparation and Optimization of Banana Fiber Reinforced Natural Rubber Composites(Uva Wellassa University of Sri Lanka, 2021) Hettiarachchi, C.L.; Kondarage, Y.G.; Edirisinghe, D.; Pabasara, W.G.A.Agro-industrial waste has become a major environmental issue in most parts of the world. Banana trees are one of the major underutilized agro by-products generated, especially in Sri Lanka. Natural fiber reinforced bio-degradable composites are good alternatives for composites produced with conventional materials. Banana fibers are cheaper, environmentally friendly, renewable and biodegradable. This work was aimed to evaluate the feasibility of utilizing fiber extracted from banana stem with natural rubber to develop a composite with enhanced mechanical properties, especially for flooring products. In this study, banana fibers were extracted and characterized using Fourier-transform Infrared (FTIR) spectroscopy. The surface of the banana fibers was modified using NaOH and Na2SO3. The surface modification was confirmed by FTIR spectroscopy. Natural rubber- based composites were prepared with different levels of banana fiber loadings with other compounding chemicals. Physico-mechanical properties of the composites such as hardness, compression set, abrasion volume loss, tensile properties and tear strength were evaluated. These properties of the composites were compared with those of the composite prepared according to the same formulation, but without banana fiber (i.e. control). Compared to the Control, novel banana fibre-filled natural rubber composites show improved mechanical properties such as lower compression set, higher abrasion resistance and higher hardness. It can be concluded that, within the limited scope of the experiments carried out in this investigation, this banana fibre-filled natural rubber composites could be utilized as a flooring material. Keywords: Banana fiber; Natural rubber; Composite; ReinforcementItem Removal and Recovery of Phosphate using Sorption from Wastewater: Effect of Process Parameters and Modeling(Uva Wellassa University of Sri Lanka, 2021) Fara, M.N.N.; Kottehewa, D.J.Wastewater contains P (Phosphorus) from human excreta, household detergents and some industrial and trade effluents in the form of orthophosphates, organic compounds and polyphosphates. Out of these, phosphate is the most available form of P. Thus, the need for the removal of excess phosphate is a necessity. Since P is a nutrient, release of wastewater containing excess P could lead to create problems of eutrophication. Apart from that, P is a finite resource, therefore, recovery of P from wastewater is also of interest. Sorption has been given importance in this regard mainly by using Activated Carbon (AC). However, use of kinetics and adsorption isotherm models to describe this P sorption process on to AC is limited in the literature. Therefore, this study is sought at describing adsorption kinetics and equilibrium adsorption isotherms of P on to AC and the desorption process to enhance the recovery of phosphate. Different reaction parameter impacts on the adsorption process were tested. Experiments were conducted with synthetic solutions having an initial P concentration of 25 ppm prepared by using KH2PO4. Results of the kinetic study done in triplicate showed that the phosphate removal reached its maximum value (38.37%) after four hours and thirty minutes. The Elovich model fit well with the kinetic study experimental data explaining that the rate of adsorption of P on to AC gets decreased exponentially as the amount of adsorbed P on to AC increases. Equilibrium isotherm study results suggested that this adsorption process could be well explained by the Langmuir model with the maximum adsorption capacity of -0.5488 mg g-1. The results also revealed that the pH of the solution significantly influences the adsorption process as P removal efficiency is considerably decreased from lower pH to higher pH. Desorption study w results showed that the phosphate adsorbed by AC could be successfully desorbed using 1 M NaOH solution up to 84.17% after 1.6 hrs. Keywords: Phosphorus; Adsorption; Elovich model; Langmuir model; DesorptionItem Investigating the Potential of Clay Brick Waste to Be Used as a Raw Material for Rice Husk Ash-Based Bricks(Uva Wellassa University of Sri Lanka, 2021) Rajapaksha, R.P.T.N.; Wijerathne, W.D.C.C.Rice husk ash (RHA) and clay are well-known pozzolan materials that can be incorporated to tailor the properties of commercial bricks in the construction industry. Clay brick waste (CBW) is a clay product that is largely generated during mass-scale demolition activities. Although several works reported the use of RHA for developing bricks with improved physical properties, no work investigated how CBW influence the performance of RHA-based bricks. Accordingly, this work investigated how brick waste can be incorporated into RHA-based cement brick and how its properties such as compressive strength, water absorbency and morphology are influenced. For this, untreated RHA (particle size: 63-500 μm), CBW, OPC cement and water were used, and several bricks with dimensions 7×5×3 cm were developed by using different volume mixing ratios. The optimum mixing ratio among constituents was determined based on the brick’s porosity, surface finish and de-moulding capability. Results indicate that the optimum volume mixing ratio is 2:3:6:1 (cement: CBW: RHA: water). The RHA content should be less than 13% w/w to ensure de-moulding Having BCBW content of more than 44% w/w is acceptable for a better product, but too high contents around 64% w/w are not desirable as it discourages the removal of the brick for the mould. The brick with the optimum mixing ratio shows a water absorbance of 51% w/w and compressive strength of 3.61 MPa (28 days). Without RHA, the brick maintains the same compressive strength while reducing the water absorbance down to 20%. Compared to bricks reported in the literature using RHA/clay, RHA/lime/cement, RHA/aggregates, the proposed brick has significantly high water absorbency, and the compressive strength is around the reported values. Considering its properties, and the presence of heavy-metal-adsorptive RHA, the brick can be proposed for construction areas where wastewater channels are involved. Keywords: Rice husk ash; RHA; Clay brick waste; Compressive strength; Water absorbance; Optimum mixing ratioItem Application of Thermally Reduced Graphene Oxide-based Counter Electrode for Dye- sensitized Solar Cells: A Comparative Study on Sintering Temperature(Uva Wellassa University of Sri Lanka, 2021) Kumari, J.M.K.W.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.A counter electrode (CE) fabricated with thermally reduced graphene oxide synthesized from Sri Lankan graphite is proposed for promising Platinum-free dye sensitized solar cells (DSSC). As it is well known, Sri Lankan natural graphite has become more attractive and demanding in the world due to its high purity and high crystallinity. In a DSSC, a thin film of Platinum (Pt) is generally used as the catalytic material on the CE due to its high conductivity and superior electro-catalytic activity. However, there is a considerable attention to replace Pt based CEs due to their high cost and limited supply. Recently, extensive research has been performed on using carbon materials for the CEs due to their low cost, high conductivity and good catalytic activity. In this study, reduced graphene oxide (RGO) was synthesized and deposited on FTO conducting glass substrate by spray method. To investigate the effect of sintering temperature of the CE on the performance of DSSCs, a series of RGO based CEs were prepared with different sintering temperatures from 100 oC to 300 oC by increasing the temperature by 50 oC intervals. Results confirmed that the DSSCs prepared with sintered CEs exhibit a better photovoltaic performance compared to the DSSCs made with un- sintered CEs essentially due to the enhanced adhesion to the FTO glass substrate in the sintered composite material. DSSCs with CEs sintered at 250 oC have exhibited the highest efficiency of 4.52 % compared to the DSSC with un-sintered CEs (efficiency=1.35 %). This low cost RGO CE exhibits good stability and acceptable efficiency compared to Pt CE (7.82 %) in DSSCs operating under similar conditions. Synthsized RGO sheets were characterized using scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The electro-catalytic activity of RGO CE was determined by cyclic voltammetry. Results suggested that this CE can be one of the alternatives to the Pt CEs in DSSCs with further modifications. Keywords: Dye sensitized solar cells; Counter electrode; Reduced graphene oxide; Sintering temperatureItem Development of a Novel Composite Tile using Meetiyagoda Kaolinite Reinforced with Polylactic Acid (PLA)(Uva Wellassa University of Sri Lanka, 2021) Herath, H.M.D.M.I.; Hewathilake, H.P.T.S.Sri Lanka has high quality Kaolinite deposit in Meetiyagoda that govern by the Lanka Ceramic PLC and refined kaolinite has provided to the local ceramic industries. Kaolinite, is a layered silicate clay mineral composed with low shrink–swell capacity and cation-exchange capacity. Mostly ceramic tile production is suffering with cracking, low strength, high weight and less waterproof capacity. Hence, ceramic tile industry has been updating with product advancement gradually since last decades. Specially, the evolution of tile body formulations and technological behavior of clay composite materials have taken in to attention. This trend has taken step forward with introducing novel composites by mixing polymer materials with raw materials. Polylactic Acid (PLA) is a blend composite having low stiffness, high tensile strength and high gas permeability. Therefore, the present study is focused on develop a composite material by mixing PLA and kaolin in order to obtain low weight, high strength and waterproof ceramic tiles. Initially Kaolin samples were collected from Meetiyagoda Kaolinite deposit and all the samples were tested for moisture content & were subjected to physical purification by mixing with distilled water and obtained a milky color clay solution. After that dried clay samples were powdered and 125 micron size fraction was obtained by mechanical sieving. Then while PLA was heating to its melting temperature (1700C), kaolinite was added time to time (ratio in 50:50) into PLA container and mixed using a heat stirrer in 1700C for 30 min to develop a slurry which then set up in a mould. Then the prepared novel composite tile sample was tested on water absorption, compressive strength & crystal structure was tested by using the X- Ray diffraction (XRD).As an overall result the novel tile sample shows almost 0% water absorption with time and also it is very light in weight with a considerable amount of strength. This novel tile can be developed with low temperature (1700C). Therefore, the product is cost effective. Future of this research can be directed to enhance more properties based on what material used to reinforce the kaolinite (Ex: Glass fiber, Silica, graphite) and we can use this reinforced kaolinite as a raw material to develop a novel cement (plaster) to apply in building constructions. Keywords: Kaolinite; PLA; Novel reinforced tile; Water absorptionItem Fabrication of Biodegradable Composite Packaging Film from Banana Fibers(Uva Wellassa University of Sri Lanka, 2021) Imalka, V.P.A.; Rambukwella, M.Plastic Polymers are the most popular petroleum-based material used in food packaging, due to their low cost and functional advantages. As a result of improper waste management, these materials take considerable time to decompose. After harvesting crops, both banana pseudo- stems and leaves are disposed of as landfills and this leads to increase environmental pollution. Biodegradable packagings made up of natural fibers and other environmentally friendly materials are being used to reduce this issue. These materials are eco-friendly and decompose rapidly in ambient conditions. The purpose of this study was to prepare a biodegradable composite film for food packaging using alkali and bleached banana pseudo-stem fibers, polyvinyl alcohol (PVA) and titanium dioxide (TiO2). Composite films were prepared using the solution casting method. In brief, NaOH was used as a pretreatment chemical and NaOCl/ CH3COOH were used in the bleaching process where incorporating the latter step produced pure cellulose with respect to the alkali pretreatment. The compositional effect on the structure and properties of the resulting films were investigated and synthesized films were characterized using Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). FT-IR showed more prominent peaks for bleached cellulosic fibers indicating pure cellulosic fibers. Furthermore, SEM analysis showed a smooth surface for bleached composite film and a rough lignin-based surface for the pretreated composite film. Due to the photocatalytic effect of TiO2 an enhanced antibacterial resistivity was observed in the composite films. Biodegradability test showed biodegradation upon three days at ambient soil condition whereas Water Vapor Permeability (WVP) test and water solubility tests showed, lowest water solubility and WVP at 25% fiber loading. The highest tensile strength of 42.9 N/mm2 was observed for PVA+bleached fiber (25%) +TiO2 film with effect from the increase in fibre-matrix adhesion. Furthermore, it was observed that incorporating bleached fibers resulted in an increased tensile strength from 4% to 6%. Banana pseudostem fibers in combination with PVA and TiO2 demonstrated to be a potential biodegradable composite packaging film with enhanced antibacterial resistance. Keywords: Composite; Banana fibers; Pseudostem; Packaging; PVA; TiO2Item Development of a Silicone Dielectric Polymer for Actuators(Uva Wellassa University of Sri Lanka, 2021) Dissanayake, D.M.N.T.; Asela, A.U.; Premarathna, A.K.C.P.; Tennakoon, G.A.A.I.; Samaraweera, R.L.Virtual 3D environments (Virtual Reality) are created inside computers to deliver thermal, vibrational, and force feelings. Haptics technology brings this virtual world to end-users by haptics goggles and gloves. Tactile displays have been developed to deliver sensations in haptics gloves. In this regard, actuators act as movers in tactile displays stimulating sensations to skin receptors inside the fingertips. Dielectric polymer-based actuators are prominent in the world due to lightness, lower energy loss, and simplicity leading to wearable haptics gloves. Acrylic and silicone are the major types of dielectric polymers used for actuators. Silicone dielectric polymers have excellent properties such as faster response (3 s), efficiency, lower mechanical loss, and thermal stability comparing to acrylic. But silicones unable to achieve greater electro-strains (>10%) as it’s in acrylic-based actuators. This research work focused on enhancing the electro-strain property of silicone dielectric polymer by blending polyaniline particles. The electro-strain property of dielectric polymers depends on both dielectric constant and elastic modulus. Increased dielectric constant and decreased elastic modulus improve the electro-strain of actuators. Polyaniline has positive and negative charges itself which can be utilized to improve the dielectric constant of silicone polymer. Also, dispersed particles can change the elastic modulus of the matrix material. In the procedure, polyaniline and Dow corning silicone (DC 3481) were mixed in 0.0wt%, 0.5wt%, 1.0wt%, 1.5wt%, and 2wt% compositions and stirred for six hours. Next, thin films (thickness-125 m) were prepared using the Doctor blade technique on PVC (Polyvinylchloride) sheets. Crosslinking process was carried out for 24 hours. In characterization, 2wt% Dow corning silicone (DC 3481) and polyaniline polymer blend showed the 41.76% increment in dielectric constant, and elastic modulus was decreased by 68.71% compared to pure Dow corning silicone (DC 3481). This composition achieved the best matching electromechanical properties in dielectric constant and elastic modulus to apply in actuators. The developed polymer is recommended for haptics gloves to deliver enhanced force and vibration. Moreover, the Doctor blade technique can be introduced to fabricate thin films in actuators which is simple and cost-effective. Keywords: Virtual reality (VR); Actuators; Dielectric constant; Elastic modulusItem Optimization of Photovoltaic Performance of Electrospun PVdF-HFP Nanofiber Membrane Based Dye Sensitized Solar Cells with Membrane Thickness(Uva Wellassa University of Sri Lanka, 2021) Hettiarachchi, M.S.H.; Dissanayake, M.A.K.L.; Senadeera, G.K.R.; Umair, K.Electrospinning is a versatile and efficient method to fabricate polymeric nanofibers with attractive properties such as the large surface area to volume ratio, better pore interconnectivity, and superior mechanical performances, which can be extended to applications in Dye Sensitized Solar Cells (DSSCs). Hence, to overcome the problem of poor long-term stability of conventional liquid electrolyte based DSSCs, the use of electrospun polymer nanofiber membrane-based gel electrolytes is a possible option. The DSSCs with polymer nanofiber-based gel electrolyte, made by trapping a solution electrolyte within a three-dimensional matrix made of polymer nanofibers exhibit almost liquid-like ionic conductivities while offering better mechanical and chemical stability than conventional liquid electrolyte based DSSCs. In electrospinning, there are various processing parameters, which significantly affect the characteristics of fiber membrane. In this work. a systematic study was performed to analyze the influence of membrane thickness on the photovoltaic performance of the DSSCs, which was assumed to be proportional to electrospinning time. Poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) nanofiber membrane was fabricated using the electrospinning method and in order to vary the membrane thickness of the nanofiber mat, electrospinning time was varied. Scanning Electron Microscopic images have shown that the PVdF- HFP membrane consists of porous, thin nanofibers with an average fiber diameter of 80-100 nm. The host polymer membrane was soaked in the solution electrolyte made with iodine (I2), potassium iodide (KI), and tetrapropyl ammonium iodide (Pr4NI) dissolved in ethylene carbonate (EC) and propylene carbonate (PC) co-solvent. The short circuit current density (Jsc) and light-to-electricity conversion efficiency (η) have shown almost similar variation with the duration of electrospinning. Both parameters have gradually increased to a maximum value and then has decreased with electrospinning time. Maximum efficiency (η) of 5.96% was observed for the DSSC fabricated with optimized nanofiber membrane, corresponding to 4 minutes of electrospinning time. The open circuit voltage (Voc), short circuit current density (Jsc) and fill factor were recorded as 693.4 mV, 14.6 mA cm−2, and 58.86% respectively at an incident light intensity of 1000 W m−2 with a 1.5 AM filter whereas the conventional liquid electrolyte cell showed an efficiency (η) of 6.56%. Keywords: Dye sensitized solar cells; PVdF-HFP co-polymer; Nanofiber gel polymer electrolyte; ElectrospinningItem Synthesis of Microwave-Assisted Low-cost Graphene Using Natural Vein Graphite in Sri Lanka(Uva Wellassa University of Sri Lanka, 2021) Rathnayaka, R.M.D.P.K.; Pitawala, H.M.J.C.; Wijesekara, K.B.; Samaraweera, R. L.Graphene is a planar monolayer of carbon atoms arranged into a two-dimensional honeycomb lattice. Due to the exceptional properties of graphene, it has a variety of industrial applications. Graphite remains the most popular precursor for large-scale graphene synthesis or low-cost production. The modified Hummers method and the Staudenmaier method are the popular techniques in which raw graphite is converted into a much valuable form of graphite called graphene oxide. As prepared graphene oxide, then reduce to prepare reduced graphene oxide (rGO). However, the Hummers method has some drawbacks and diminishes the physical properties of prepared graphene. As a result, alternative methods for synthesizing graphene from graphite are necessary. In this study, microwave radiation and low-cost, eco-friendly chemicals (H2O2 and commercial liquid hand wash) have been utilized to synthesize graphene from natural vein graphite in Sri Lanka. In this technique, the H2O2 and liquid hand wash intercalated natural vein graphite powder in an aqueous medium was microwave irradiated at 400 W for 5 min. Then, the microwave irradiated sample was sonicated for 30 mins to obtain the dispersion containing graphene flakes. The resulted graphite intercalated compound was characterized using the X-ray diffraction (XRD) method, and the prepared graphene dispersion was characterized using UV–visible spectroscopic technique. The XRD data exhibit a successful production of graphite intercalation compound. The UV-Visible data reveal that the sonicated aqueous dispersion contains graphene, although no indication of graphene oxide in the samples. This process has the advantage of manufacturing graphene quickly while using natural graphite and environmentally friendly chemicals. Keywords: Sri Lankan vein graphite; Graphene; Microwave irradiation; IntercalationItem Fabrication & Characterization of a Novel Soap Material Based on the selected Value- Added Sri Lankan Clay Minerals with Extracted Saponin from Dry Fruit of Sapindus emerginata(Uva Wellassa University of Sri Lanka, 2021) Delpechithra, N.T.; Premarathne, E.P.N.; Pitawala, H.M.J.C.Soap referred to as stain removal material as a result of a saponification reaction between lye solution and fat/oil. In some soap industries clay minerals are used as a filler material which facilitate the structure and riser attribute of soap. Instead of that these clay minerals have the ability to remove stain and exfoliate the dead skin and act as a moisturizer. There are many clay types that can be found locally which are related to kaolin. However, those clay types do not showcase some qualities such as anti-bacterial effect, anti-fungal effect, moisturizing effect, foaming effect related to skin care. Therefore, those natural clay types have not been used previously for cosmetic purposes. Under this investigation, a non-ionic natural bio surfactant called saponin which was extracted from the dry fruit of Sapindus emerginata (soapnut) was used to improve above mentioned lacking qualities. Saponin makes skin soft and acts as moisturizing agent, gentle foaming agent, natural exfoliant, and very good anti- fungal and anti-bacterial agent. Four clays were used for this investigation. Except montmorillonite clay, other three were obtained from different areas of Sri Lanka i.e; kaolin clay from Meetiyagoda, kirimati from Kandy, Makulu clay from Wadduwa. From each clay type, three samples were prepared by varying the clay amount as 2g (6.7 wt%), 4g (13.3 wt%) and 6g (20 wt%) by maintaining the temperature of the solution as 30 °C in order to find out the best clay species for soap production. Each of the sample were tested for the TFM value, total alkalinity content, moisture content, foam height and pH value. These values were compared with the international standards of soaps. Almost all the parameters of prepared soap samples were within the standard ranges. As per the results, Meetiyagoda clay and Makulu clay were the best clays for soap production and the best composition is 20 wt% which contain 6g of clay. Keywords: Kaolin; Sapindus emerginata; saponin, montmorillonite; Saponification