Master of Science in Materials Science

Permanent URI for this collectionhttp://192.248.9.226/handle/123/15929

Browse

Browsing Master of Science in Materials Science by Author "Amarasinghe DAS"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    item: Thesis-Full-text
    Cost effective method to analyze lubrication oil
    (2020) Rathnayake TNA; Amarasinghe DAS
    The lubricating oil analysis is the most common method to identify the condition of any machinery. There are various ways to analyze lubricating oil, and those methods are based on an individual examination of lubricant properties such as Viscosity, Total Base Number (TBN), Total Acidic Number (TAN), Water Content, Impurities (element analysis), etc. However, to carry out these analyses, sophisticated pieces of equipment are required. They are costly and need specific environmental conditions. Furthermore, as the tests are done in a laboratory, away from the machine, carefully collected lubricating oil samples must be transported to them. The whole process, from collecting samples to obtained results, takes a considerable amount of time. Therefore, this process will hamper the maintenance program's efficiency since the machine has to be kept in idle until receiving the results. Hence, it is of utmost importance to have a cost-effective and faster results-giving method to analyze lubricating oil at the place where the machines are installed. Then the operator himself can check the condition of lubricating oil to ensure the safe and smooth operation of the machine. A comprehensive literature survey was carried out to understand the current trends in lubricating oil analysis. Most of the tests described in the literature are based upon Physical, Chemical, Electro-magnetic and Optical methods. The proposed design is based on an optical technique that deals with the Refractive Index (RI) since it is an indicator of the physical as well as the chemical property characteristic of a substance. The critical angle of a material is directly related to RI. Therefore, monitoring the critical angle changes leads to an understanding of the quality of the lube-oil. During the design stage, special attention was paid to the cost of the fabrication and user-friendliness of the device. The performance of a proposed lube-oil analyzer was assessed using Shell Gardenia 40 (lubricating oil used in high-speed marine engines of Fast Attack Craft) lubricant. The lubricant used for different operating hours were analyzed. This analysis unveiled that, though Original Equipment Manufacturer (OEM) emphasize changing the lubricating oil after 500 hours, lube-oil quality has not deteriorated below the specified levels at this stage. This shows that the lifetime of lube-oil can be further extended, and frequent quality testing of lube-oil can save large sums of money without putting the machine life into any danger. The results obtained from the proposed device was compared with the tests carried out according to the American Society for Testing and Materials (ASTM) standards. Moreover, forced diluted lube-oil samples were analyzed using the proposed device. Both tests confirm the effectiveness of the proposed device.
  • Thumbnail Image
    item: Thesis-Full-text
    Derivation of nanofibrillated cellulose from locally available rice straw
    (2020) Ratnakumar A; Samarasekara AMPB; Amarasinghe DAS
    Cellulose has become a wonder material in the present context of research and development since it is fibrous and tough, hence biodegradable, biocompatible, and renewable natural polymer. Nowadays, rice straw as a cellulose source has gained momentum as rice is one of the major crops grown in most of the tropical and subtropical countries of the world where half of the world population consuming it as the major food source. Rice straw is the agricultural production residue from rice cultivation which is considered as an agricultural waste and cause decay related issues in the plantation. This biological waste material if utilized can be a renewable feedstock for the production of value added products for special applications. Sri Lanka being an agricultural country holds twentieth position in the worldwide rice production. However, a large amount of rice straw is generated per annum as a by-product of rice production in the country. Even though rice straw is utilized in various ways, there is a possibility for a value addition by extracting its constituents such as nanofibrillated cellulose from this commercially underutilized waste material and thereby embracing a bioeconomy approach in the country. In this study, nanofibrillated cellulose (NFC) was extracted from Sri Lankan rice straw varieties BG352, Murunkan, Pachchaperumal and Moddaikaruppan in two distinct stages. Initially, rice straw was subjected to a series of chemical traetments to eliminate the non-cellulosic constituents. Then the obtained chemically extracted cellulose fibers were separated into nanofibers via high-intensity ultrasonication (HIUS) treatment. Structural, thermal and morphological characteristics of nanofibers and their intermediate products were determined. FTIR analysis confirmed that the chemical composition of nanofibers was mainly cellulose where amorphous natured hemicellulose and lignin were effectively removed during chemical treatments. Study revealed that around 25 - 38 percent cellulose was extracted from the four rice straw varieties via chemical process. From these chemically extracted cellulose fibers around 17 - 45 percent of nanofibrillated cellulose were extracted via high-intensity ultrasonication process. Morphology of rice straw during the extraction process was distinct when the non-cellulosic components were removed. Results indicated that the efficient multi-step treatment process yielded nanofibers with potential advanced applications. Chemical extraction method is found to be the most efficient method for cellulose extraction from lignocellulosic biomass. Therefore, it is of paramount important to investigate the influence of parent materials on the synthesis process and the properties of the yield. Effect of particle size distribution of locally available traditional rice straw Murunkan on cellulose extraction was studied. Study revealed that after the series of chemical treatments rice straw with particle size distribution below 75 μm (Mu-75) yielded 27.19 ± 0.98 percent and rice straw with particle size distribution between 150 μm to 250 μm (Mu-250) yielded 38.31 ± 0.86 percent. Out of these cellulose fibers, around 63 percent of NFC was extracted from Mu-75 and around 55 percent of NFC from Mu-250. SEM images showed that the diameters of the extracted nanofibres from Mu-250 ranged from 75 to 200 nm whereas nanofibers from Mu-75 ranged between 27 – 104 nm. These findings will have profound influence upon extracting nanofibrillated cellulose from agricultural biomass.
  • Thumbnail Image
    item: Thesis-Full-text
    Extraction and characterization of microfibrillated cellulose from textile cotton waste
    (2020) Jayasinghe JMR; Samarasekara AMPB; Amarasinghe DAS
    Cotton is a natural staple fiber that almost consist with cellulose compared to wood. The major economic value of the cotton is in Textile Industry. In the past recent years, cotton consumption demand was increased than the production. In textile industry cotton are blending with various other synthetic fibers such as polyester, nylon and lycra to obtained desirable properties. Therefore, the fabric recycling methods are quite complicated although it is highly available as pre-consumer garment waste. In this work a method was developed to identify the amount of cotton present in the cotton/polyester blended fabric by using Fourier transformed infrared (FTIR) second-order derivative spectrum. Then the cotton waste composition was determined and used to extract cellulose. Then purify cellulose was subjected to extract Micro Fibrillated Cellulose (MFC) by using acid hydrolysis method. MFC has very high economic value compared to cotton fabric waste in various applications such as bio-composites, medicine, cosmetic, pharmaceutical, tissue engineering, bio-sensors, paints and coating, flexible electronics, air filters and high tech applications including aviation and automobile. However, the major challenge of extracting MFC is the low amount of yield in acid hydrolysis, although it considered to be as most cost effective method of MFC extraction. Laboratory extracted small quantities are not sufficient in industrial applications such as in reinforcing composites. Three experimental factors including; acid concentration, hydrolysis time and temperature show the highest effect in yield and quality of MFC. Therefor this experiment was designed to optimize the three independent factors effect on two responses of yield (%) and Width (nm) of MFC. Response surface methodology was employed to design the experiment and ANOVA statistical test results were used to determine the significance of the parameter effect on acid hydrolysis. Further extracted MFCs physical and structural properties were discussed. Morphological features and size of the fibers were examined by scanning electron microscopy (SEM), structural features and chemical functionality was determined by Fourier transformed infrared (FTIR) spectroscopy, degree of crystallinity was obtained by X-ray diffraction (XRD) spectroscopy and thermal properties were determined by Thermo gravimetric analysis (TGA).