Browsing by Author "Udayakumara, S. V."

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item: Conference-Abstract
Enhancing mechanical properties of nylon – 6 using eggshell powder as a reinforcement
(Department of Materials Science and Engineering, University of Moratuwa, 2024) Thilakarathne, H. G. M. J.; Shirantha, D. G. S. M.; Udayakumara, S. V.
This research investigates the formation and composition of eggshell powder (ESP) obtained through two distinct methods: one involving the inclusion of the inner shell membrane and the other without. Eggshells underwent washing, drying, and milling processes to produce ESP. The impact of milling time (6, 9, and 12 hours) and method (dry and wet) on particle size was explored for both types of eggshells. Thermogravimetric analysis determined the calcium carbonate composition of ESP, while scanning electron microscopy (SEM) and ImageJ software were employed for particle size analysis. Results indicate that ESP without the shell membrane exhibited thermal stability up to 600 °C, with subsequent decomposition releasing 44.39% mass due to calcium carbonate decomposition. The composition of calcium carbonate in ESP without the shell membrane was approximately 97.68%. Conversely, ESP with the shell membrane showed a weight loss of 5.2% around 350 °C, resulting in a calcium carbonate composition of 94.34%. SEM images revealed that increasing milling time led to a reduction in particle size within a certain range, while particles started to agglomerate after 12 hours. The presence of the inner shell membrane had minimal impact on particle size. Plastomilled nylon composites with different ESP percentages (10%, 15%, 20%) were tested for water absorption percentage and hardness. Additionally, plastomilled nylon composites were tested for tensile properties. Results indicate that optimal mechanical properties were exhibited in the 15% ESP composition, and the eggshell membrane had an impact on the bonding between polymer chains and powder particles inside the matrix voids. Having an inner shell membrane improved the overall mechanical properties at 15% composition.
item: Conference-Abstract
Extraction of limonene from citrus peels and its application as an eco-friendly insect repellent
(Department of Materials Science and Engineering, University of Moratuwa, 2024) Manatunga, V. S.; Jayawardhana, M. G. C. L.; Udayakumara, S. V.; Sivahar, V.
Many plants are frequently referred to as natural pesticides because of their insecticidal qualities. The peel of the orange fruit contains large amounts of the compound d-limonene, which makes it a valuable fruit in addition to being edible. A common pesticide in commercial insect repellents is d-limonene. D-limonene, found in orange peel oil, ranges from 90 to 95 percent and acts as a repellent for ants, mosquitoes, and flies. Flies and mosquitoes are kept away from gardens by scattering pieces of orange peel around. An at-home method for avoiding mosquito bites is to rub orange peel on the skin. Important naturally occurring bioactive substances such as ascorbic acid, essential oils, and antioxidants are found in citrus species. Citrus fruit peels, which are frequently thrown away as waste, contain a complex mixture of volatile and non-volatile compounds that are extracted into essential oils. Conventional methods such as steam distillation and solvent extraction, while simple and robust, yield lower percentages. In contrast, novel methods, despite being more effective, tend to be less cost-efficient. This paper specifically focuses on refining the steam distillation process for improved extraction of orange oil, and the experimental setup involved a forced choice test, where ants were given the option to escape from a petri dish via two microscope slides: one treated with the limonene solution and one untreated as a control. The results indicated a significant repellent effect, with a much lower number of ants choosing the treated slide. This demonstrates the potential of limonene as a sustainable alternative to synthetic insect repellents.