Browsing by Author "Ratnaweera, D.R."

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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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    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.