Browsing by Author "Edirisinghe, D."

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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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    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; Reinforcement
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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.