Institutional-Repository, University of Moratuwa
Welcome to the University of Moratuwa Digital Repository, which houses postgraduate theses and dissertations, research articles presented at conferences by faculties and departments, university-published journal articles and research publications authored by academic staff. This online repository stores, preserves and distributes the University's scholarly work. This service allows University members to share their research with a larger audience.
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Recent Submissions
item: Thesis-Abstract
Effect of biomass boiler wood ash on the physical properties of rubber compound in the pneumatic tire manufacturing process
(2025) Madhuranga, HBSP; Udayakumara, SV
Processing and materials recovery of waste is an important aspect of environmental policy. Ash is waste in terms of legislation, but it is also a material that can be reused. Varius works proposed with wood ash (WA) from biomass as an inorganic fertilizer. In this study, the effect of adding biomass WA on the mechanical properties of TSR/SBR type rubber material that is used for the industrial pneumatic tire manufacturing process was investigated. The particle size of WA was observed to be 30 to 50 μm. The composition of WA was characterized by Elemental analysis, Energy-dispersive X-ray spectroscopy (EDS), and Fourier-transformed infrared spectroscopy (FTIR). Five different compounds were prepared by adding 3, 5, 8, and 10 phr WA to the filler and additive materials in the general composition. Influence of the addition of WA on the cure characteristics (minimum torque – ML, maximum torque – MH, Optimum cure time t90, scorch time tS2,), mechanical properties (tensile strength at break – TSb, elongation at break – Eb and hardness), physical, dynamic properties, and resistance to aging were investigated. The fracture surface of the compound and the shape and morphological distribution of the fillers in the rubber matrix were examined using Scanning Electron Microscopy (SEM). Production costs of the new compound proposed were compared between themselves.
As a result of experimental studies, it was found that the new compound has a good level of mechanical properties and can be used as a partial replacement of filler in the tire industry.
Key
item: Thesis-Abstract
Techno-economic comparison of cold storage configurations for summer air conditioning of high-risk commercial buildings
(2024) Hemarathne, DDUM; Wijewardene, A
This research investigates the application of thermal energy storage (TES) systems for air conditioning in office buildings located in tropical climates with high cooling demands. While integrating cold storage systems with air conditioning offers benefits such as reduced peak demand electricity costs, the ability to leverage the electricity demand to get time- based electricity tariff benefits, enhanced chiller plant efficiency, and improved condenser performance during nighttime operation, the adoption of TES technology remains limited. This is primarily due to the lack of comprehensive assessments and cost analysis related to local electricity tariff structures in various regions.
The study provides guidelines and a decision-making tool for selecting the most suitable thermal energy storage (TES) system for buildings, with a focus on load-shifting strategies to off-peak hours. It includes a literature survey to explore the fundamentals and characteristics of thermal storage systems and media for air conditioning, review software tools for cooling load calculations and system simulations, and investigate cost analysis methods and applicable electricity tariff structures for high cooling demand buildings in tropical climates. Following this, the report presents a detailed examination of TES integration with chiller plants, assessing various configurations based on factors such as energy consumption, maximum demand variations, daily energy distribution, space requirements, and implementation costs. Among the four configurations assessed, including a conventional chiller plant, a chiller plants with TES for full capacity (full storage), and two configurations with partial TES for load leveling and demand limiting, the configuration 2-2, which uses TES for partial storage-load leveling, was found to be the most cost-effective. This configuration demonstrated substantial operational savings, reduced peak demand, and required minimal space.
Payback periods for Configuration 2-2 varied by region: approximately 14 years under Sri Lanka’s July 2024 electricity tariffs, 3.28 years under Sri Lanka’s August 2022 tariffs, 1.49 years under Singapore’s current tariffs, and 6.21 years under Kerala, India’s current tariffs. The extended payback period under Sri Lanka’s latest tariffs is attributed to the reduction of the differences among daytime, peak, and off-peak electricity rates. Despite this, Configuration 2-2 remains financially favorable compared to other tariff structures evaluated
item: Thesis-Full-text
Effects of dimensional stability with appearance after machine wash and hand wash processes for woven school uniform materials
(2025) Nirosha, WD; Niles, SN
School uniform durability and appearance retention after washing are crucial factors affecting their longevity and cost-effectiveness. Maintaining good dimensional stability and appearance throughout the academic year is essential for school uniform materials. The washing process significantly affects the school uniform shrinkage, appearance, and functional and aesthetic properties. Due to the economic crisis durability of the school uniform is essential to the parents. According to the Public Utilities Commission of Sri Lanka (2022), the country experienced severe electricity shortages in 2022, largely caused by a combination of fuel short- aged and limited capacity of power-generation. During this period (2022), power cuts exceeding one hour per day became a common occurrence. People have changed their consumer behavior, buying habits and pattern (Ceylon today, 2023) and that might lead to change their washing methods. A systematic investigation would be necessary to identify the most effective washing procedure for woven school uniform white shirting, white trouser, and blue trouser materials.
This research investigated the effect of the hand and machine washing processes on woven school uniform white shirting, blue trouser and white trouser. In addition to the shrinkage effect of the material, the investigation also evaluates the appearance of materials, including colour change, surface pilling, and smoothness appearance.
According to the t-test results, a significant difference was observed in the shrinkage of machine wash in length and width direction of woven school uniform white shirting material compared to those washed by hand wash. The t-test results also reveal that significant shrinkage was observed in the length direction of the woven school uniform white and blue trouser materials which were washed in the machine wash process compared to the hand wash process, but such significant shrinkage was not observed for the width directions of the trouser materials.
item: Thesis-Abstract
Development of paper boards from selected agricultural plant residues extracted from alkaline hydrogen peroxide per-treatment method
(2025) Randimal, UJB; De Silva, GIP; Fernando , TN
This study focuses on the development of environmentally friendly paper boards using fibers derived from agricultural residues specifically bagasse, cornhusk, and rice straw combined with recycled waste paper. In the first phase, cellulose fibers were extracted from these lignocellulosic materials using the Alkaline Hydrogen Peroxide (AHP) pretreatment method. The extracted fibers were characterized through tests for tensile strength, cellulose content, weight loss, and morphological features. Additionally, Fourier-transform infrared spectroscopy (FTIR) was used to confirm the presence of cellulose and assess the structural integrity of the fibers.
In the second phase, paper boards were fabricated manually by blending pre-treated fibers with recycled paper at varying proportions (0%, 25%, 35%, 50%, 75%, 85%, and 100%). The resulting samples were evaluated for key properties, including tensile strength, tear resistance, burst strength, stiffness, and water absorption capacity. Their performance was compared against a commercially available reference paper board. The results indicated that while higher fiber content (75–100%) led to increased production costs, blends containing 50% pre-treated fibers provided a favorable balance of cost and mechanical performance, suggesting their potential for sustainable industrial application.
item: Thesis-Abstract
Suitability of using offshore sand sludge as a filler material for tile adhesive production
(2025) Suraweera, SADAS; Guluwita, SP
Offshore sand sludge (OSS) is a byproduct that is continuously collected with backwash water during offshore sand processing. OSS predominantly comprises fine sand grains and shell fragments. Chemical composition analysis and property evaluation have confirmed the presence of beneficial compounds and minimal contaminants, which indicates its potential for the development of value-added products. The particle size distribution and shell content of OSS are key factors determining its suitability as a replacement for conventional quartz and dolomite fillers in tile adhesives. In addition, the consistent particle size distribution in OSS enhances its feasibility for production processes. Tile adhesive mixtures were formulated and evaluated to identify the appropriate particle range for production. The study focused on two particle ranges which are below 0.6 mm and particles between 0.125 mm and 0.6 mm. Performance testing of the initial tile adhesive formulations were demonstrated that both particle ranges were suitable for use as fillers. However, below 0.6 mm used adhesive exhibited better physical properties due to improved packing factors. Despite this, neither formulation met the open-time requirements, which necessitated adjustments to the adhesive formulation. Subsequently, six additional formulations were tested to address the observed performance gaps in the initial mixtures. Additives and water/powder ratio adjustments were made to meet the specified requirements in accordance with international norms. The modified formulations were exhibited properties that exceeded the specified limits for the C2 category as per the ISO 13007-2. Furthermore, the formulation using below 0.6 mm OSS filler exhibited the best overall performance compared to all other mixtures. The study concludes that OSS can be effectively utilized as a filler material in tile adhesive manufacturing. The proposed formulation was thoroughly investigated and evaluated, which confirms its potential for industrial applications.