Browsing by Author "Etampawala, T.N.B."

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    Cellulose Whiskers Extracted from Banana Pseudo-Stem as Reinforcing Filler for Natural Rubber Tyre Treads Using Latex Intercalation Method
    (Uva Wellassa University of Sri Lanka, 2018) Bandara, T.A.R.W.M.M.C.G.; Etampawala, T.N.B.; Kularathne, S.; Wijesinghe, H.G.I.M.; Senevirathna, A.M.W.K.
    Reinforcing the rubber compounds using cellulose fibre is an emerging trend in rubber industry because of unique physical properties of cellulose fibre. In this study, cellulose fibres were extracted from pseudo-stern of banana using alkali treatments and converted into cellulose whiskers (CW) with high pressure defibrillation followed by acid treatment and bleaching. The CW was characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometry (XRD) and Particle Size Analyzing. Both FTIR and XRD confirm the cellulose structure. XRD studies showed that the percentage crystallinity of bleached fibres is about 69%. The particle size shows a bimodal distribution where approximately 21% of the sample has average size of 110 nm and the rest has the size of 795 nm. The purified CW was intercalated in diluted natural rubber (NR) centrifuged latex in order to prepare CW/NR composites and converted into rubber sheets. Mooney viscosity and stress relaxation coefficient of CW/NR composites were measured. The lowest Mooney viscosity and the highest stress relaxation coefficient were observed in CW/NR composites ensuring higher processability. The compounds were prepared in an internal mixture according to a tyre tread formulation, keeping the sample without CW as the control. Cure characteristics were evaluated at 120 °C and physical properties were evaluated on par with the ASTM standards. The highest cure rate and better scorch time were observed in CW/NR composite. The density, hardness, resilience, cut & chip and tensile strength of the composite were superior while tear strength and abrasion volume loss were inferior to the control. In overall, we observed that cellulose whiskers have a great potential to use as a reinforcing material for natural rubber tyre tread compounds.
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    Ceramic Waste-Based Natural Rubber Composites: An Exciting Way for Improving Mechanical Properties
    (Uva Wellassa University of Sri Lanka, 2018) Kondrage, Y.G.; Pitawala, H.M.J.C.; Thangavel, K.; Edirisinghe, D.; Etampawala, T.N.B.
    Large amounts of fired ceramic waste produced in ceramic industry do not have a proper method to reuse and dumped into landfills. These solid wastes have a major environmental and economic concern. Thus, a proper management of such solid wastes is eminent. Since fired ceramics have already been sintered, their utilization as a raw material is limited. This research is dedicated to evaluating the possibility of using such ceramic waste as a low-cost filler material in the manufacture of natural rubber based composites. Ceramic particles smaller than 125 µm were selected for the preparation of our initial composites. For the latter part of the study, particles in submicrometer length scales were used. Elemental analysis and composition of the phases of the ceramic particles were determined by x-ray fluorescence and diffraction, respectively. The average particle size was characterized by scanning electron microscope (SEM) and digital particle size analyzer. The surfaces of the sub micrometer size ceramic particles were modified using Silane69 coupling agent and Oleic acid. The surface modification was confirmed by fourier-transform infrared spectroscopy, thermogravimetric analysis and SEM coupled with energy-dispersive x-ray spectroscopy. Natural rubber based composites were prepared with different levels of ceramic filler loadings. The mechanical properties of the composites such as hardness, resilience, compression set, abrasion volume loss and tensile properties were evaluated. These properties of the composites were compared with those of the composites prepared according to the same formulation except the ceramic filler (pristine rubber sample). The composites were found to have an exciting enhancement of mechanical properties with respect to the pristine rubber sample. The mechanical property improvement is higher when the ball milled sub-micrometer size ceramic filler is used and it is even better when surface modified ceramic particles are used.
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    Development of Poly Urethane based Composite using Plastic Waste of PET Bottles and Agro Waste
    (Uva Wellassa University of Sri Lanka, 2019) Kirushanthi, T.; Pitawala, H.M.J.C.; Edirisinghe, D.; Ratnaweera, D.R.; Etampawala, T.N.B.
    In general, more than 75% of the materials which are daily used by a human being are made out of polymers. But most of them are very hazardous to the environment and human health. If these polymers are recyclable at least waste problems can be mitigated. Most of the plastic products contain fillers in order to minimize the production cost. Silica is one of the commonly used filler which is mostly produced from the sand rich with silica. The silica production involves hazardous chemicals too. We found that silica can be effectively extracted from the rice husk ash using precipitation method. This silica may be used as a filler to improve the mechanical properties of the polymer. Also, we are mainly focusing to give a solution to waste management of Poly Ethylene Terephthalate (PET) based plastics and rice husk. Specifically, in this work we degrade PET waste using glycolysis method to get hydroxyl terminated-PET (h-PET) molecules that can be used as a precursor to make polyurethanes (PUs) with commercially available diisocyanates. Further, the synthesized PU is reinforced by introducing silica extracted from rice husk ash. Series of PU samples were made from varying the wt% ratio of hydroxyl terminatedPET molecules and methylene diphenyl diisocyanate (MDI). Formulated PUs were characterized using Fourier transform infrared spectroscopy (FT-IR). The optimum ratio of MDI to h-PET was found to be 1:1 which was confirmed by the results of FT-IR. Extracted silica was characterized using FT-IR, X- ray diffractometry, X-ray fluorescence spectrometry and scanning electron microscopy. Different wt% of extracted silica was incorporated to the synthesized PU. Interestingly, we found that the free diisocyanate of MDI form new chemical bonds with silanol groups present in extracted silica which was confirmed from FT-IR analysis. Thus, the enhanced mechanical properties in the composite were accounted due to the formation of well mixed silica particles in the PU matrix.
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    Fabrication of Solid State Dye Sensitized Solar Cell Using Red Sandalwood as Natural Sensitizer
    (Uva Wellassa University of Sri Lanka, 2018) Liyanage, P.L.D.R.; Etampawala, T.N.B.; Sirimanne, P.M.
    Commercially available dye-sensitized solar cells contain synthetic-metal centered dyes as a sensitizer. Natural dyes obtained from plants are a cheaper alternative for high cost synthetic dyes. The Main objective of this research is extraction of a natural dye which has wide availability with minimal chemical procedure to reduce cost of production and toxicity. The study intended in developing a solid-state-dyesensitized solar cell by sandwiching red-sandalwood pigments in between porous TiO2 and CuI films.Ti02 films were prepared on conducting glass substrates by using two different methods to obtain two different thicknesses and their morphologies were studied. According to the absorption spectra, presence of multiple layers increase the intensity of absorption of thicker (>10 p,m) TiO2 than thinner (<10 [tm) TiO2 film. Optical microscopic images of different TiO2 films show that thicker (>10 p.m) TiO2 film has no cracks present. Due to the absence of cracks in thicker TiO2 film, solid electrolyte cannot reach to glass substrate and therefore, no short current occurs. Red-sandalwood dye extracted to three different solvents (ethanol, acetone, acetonitrile) using soxhlet extraction and rotary evaporation. In each solvent three major electron transitions observe for redsandalwood extractions. Therefore, these three solvents are acceptable for extraction of red-sandalwood to use as sensitizer. A significant red shift in the absorption spectrum can be observed after chelating red-sandalwood pigments with TiO2 compare to that of dye in solutions. Formation of red sandalwood-Ti complex may be the reason for the observed red shift in the absorption spectrum. The bond formation between TiO2 and natural red-sandalwood pigments was confirmed by FTIR measurements. The deposition of hole-transfer (CuI) was eliminated problems encounter with the liquid electrolyte in photovoltaic cells. The morphology of CuI layer was studied. This demonstrates that triethylamine-hydrothiocyanate can control the formation of crystals of CuI by acting as a surfactant. Key words: Red-sandalwood, Solid-state dye sensitized solar cell, Ti02, Soxhlet extraction
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    Production of Biodiesel from Yellowfin Tuna (Thunnus albacares) Fish Skin Wastage
    (Uva Wellassa University of Sri Lanka, 2018) Amangilihewa, G.V.; Mahaliyana, A.S.; Kariyawasam, M.G.T.R.; Abeyrathne, E.D.N.S.; Etampawala, T.N.B.
    Yellowfin tuna (Thunnus albacares) is one of the major exporting fish species in Sri Lanka. Approximately 50% of the total large pelagic catch in Sri Lanka constitutes tuna-like fish species and usually fillets, steaks, cubes are exported. The rest, which is approximately 1/3 of the harvest is discarded which contain head, skin, tail, viscera and fins. Roughly 5000 tons of fish waste are generated every year in Sri Lanka. Dumping such waste in to the environment can cause various environmental problems. This study was focused to add value to such waste by producing biodiesel as an alternative energy source for petroleum. Tuna fish skins were collected from local processing factory and brought to the laboratory under 4 °C and cut in to small pieces. Fish oil was extracted using different solvents; absolute ethanol, ether, nhexane and 1:1 mixture of ethanol and water using ultra sonication and soxhlet extraction method. Fatty acid profile, energy and the yield was calculated. Accordingly there were no any significant difference in yield of the extracted oil with single solvents used (p > 0.05). But ether was selected as the best solvent (3.24 g±0.61). Among the two methods, Soxhlet method showed the highest oil yield (20 mL/kg of fish skin). Fish oil profile was obtained by using Thin Layer Chromatography (TLC) and Gas Chromatography-Mass Spectroscopy (GC-MS). The extracted oil was used to produce biodiesel using single step transesterification with potassium methoxide. The percent conversion of oil in to biodiesel was 88%. Fourier Transmission Infrared (FTIR) Spectroscopy method was used to characterize the fish oil as well as the biodiesel. The energy capacity of the synthesized biodiesel was measured using a Differential Scanning Calorimeter. All the test results were benchmarked against the commercially available petrochemical based diesel. Accordingly, ether soxhlet separation can be used as a potential biodiesel production from Yellowfin tuna fish skin.
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    Silica Extracted from Rice Husk Ash as an Effective Reinforcing Filler for Natural Rubber Composites
    (Uva Wellassa University of Sri Lanka, 2018) Samaraweera, K.C.; Wijesinghe, H.G.I.M.; Etampawala, T.N.B.; Edirisinghe, D.G.; Senevirathna, A.M.W.K.
    Rice husk is abundantly available in Sri Lanka, which is generated in larger volumes as rice husk ash (RHA) due to combustion. In general, RHA dumped at landfills as a waste. However, RHA is a promising source of silica as it contains more than 90% by weight. This silica can effectively be extracted by Sol-Gel method. In this research such silica was extracted and characterized using Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffractometry (XRD). Both FTIR and XRD analysis confirmed the chemical and amorphous nature of the extracted silica. Natural rubber composites were prepared incorporating silica from 0-10 parts per hundred Rubber (phr) at 2.5 phr intervals using two-roll mill. The effect of silica on curing characteristics and the mechanical properties of vulcanizates were studied. The curing characteristics of the compounds revealed an increase in cure rate and thus considerable decrease in cure time and scorch. Tensile strength, modulus at 100% elongation and tear strength has increased significantly compared to control sample. The effect is prominent with increasing the silica loading. The abrasion volume loss has significantly decreased with the increase of silica loading. The lowest abrasion volume loss and the highest tear strength have reached at 7.5 phr of silica loading level. Whilst the resilience has decreased when increase the silica loading. However, silica loading does not show an impact on hardness. In conclusion, preferred curing characteristics and improved mechanical properties have been achieved. Moreover, it is important to emphasize that in this study the effect of extracted silica on mechanical properties of NR composites has not been compared with the commercially available silica and further studies are suggested.
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    Silica from Rice Husk as an Alternative to Commercially Available Silica Fillers in Tyre Compounding
    (Uva Wellassa University of Sri Lanka, 2018) Kirushanthi, T.; Pitawala, H.M.J.C.; Edirisinghe, D.; Ratnaweera, D.R.; Etampawala, T.N.B.
    Rice husk is one of the major agricultural wastes. It is currently dumped into landfills in its raw form or is used as an alternative energy source. When burnt for energy it results in rice husk ash (R1-1A) which is disposed without use. RHA has very high economical value since approximately 90% RHA is silica. Thus, a proper management of such solid wastes can add value to rice industry. This work presents the extraction of silica from RHA using precipitation method, characterization and utilization of such silica as an alternative to commercially available silica in rubber compounding. The extracted silica was characterized using Fourier transform infrared spectroscopy, X- ray diffractometry, X-ray fluorescence spectrometry and scanning electron microscopy (SEM). The results were benchmarked against commercially used silica. The extracted silica has comparable chemical and amorphous properties as commercially used silica in rubber compounding. The SEM study confirmed, the extracted silica is in sub-micrometre length scale in size. Tyre compounds were made using extracted silica and commercially available silica by keeping other ingredients and conditions same. Mechanical properties of both compounds were evaluated. Silica from RHA added composite showed boost in resilience and drastic decrement in tensile and tear strength, elongation at break, abrasion resistance and hardness compared to the composite made using commercially existing silica. Both composites showed moderately similar value of 100% and 200% modulus. With the extracted silica, the fly off while mixing was less. Then, it needs higher mixing time. Compound viscosity drastically reduced and became soft after mixing. These preliminary works confirm that extracted silica cannot be used, as it is to get the comparable properties in rubber compounding as commercially available silica does. Thus, further improvements in extracted silica are being carried out to make it compatible with rubber.