Browsing by Author "Samarasekara, AMPB"

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item: Conference-Full-text
Analysing Non-Isothermal Curing Behaviour of Natural Rubber Compounds By Mathematical Modelling of Oscillating Disc Rheometer Curves
(IEEE, 2018-05) Weragoda, VSC; Samarasekara, AMPB; Chathuranga, D
This study investigates a novel way of analyzing the rheometer curves obtained from an Oscillating Disk Rheometer (ODR) for predicting the non-isothermal curing characteristics of a rubber compound. A mathematical function is proposed to predict the change in the observed rheometer torque as a function of the temperature to model the state of cure under transient temperature conditions. This was achieved by modeling the rheometer curve with the aid of six temperature dependant parametric constants. The proposed function was observed to accurately describe, the shape of the torque rate at any given temperature. The characteristics variation of the parametric constants too have been briefly examined.
item: Conference-Full-text
Atmospheric cold plasma to improve printability of polyethylene terephthalate
(IEEE, 2021-07) Sandanuwan, T; Hendeniya, N; Attygalle, D; Amarasinghe, DAS; Weragoda, SC; Samarasekara, AMPB; ; Hemachandra, K; Adhikariwatte, W; Rathnayake, M
Though paper is still the most common substrate in the printing industry, polymeric substrates are becoming common by the day. Commercially available polymers such as polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polypropylene (PP) surfaces have lower density of polar functional groups. Thus, the adhesion characteristics of these materials are naturally poor. Consequently, producing a quality print on such polymer substrates has become a challenge. Hence, surface modification has become a necessity for such surfaces. This study investigates the technical viability of cold plasma-based surface treatment technologies on polymeric materials. The effect of plasma pre-treatment, on the printability of PET substrates, was studied. The surfaces of these polymer substrates were subjected to different cold plasma treatments, using 80% N2 and 20% O2 as feed gas. The study covers the effect of the plasma dose and the plasma intensity on the printability and the degree of surface modification. The study determined the optimum plasma conditions for quality and durable prints.
item: Conference-Full-text
Chemical modification of microcrystalline cellulose using sunflower oil
(IEEE, 2020-07) Rathnayake, WSM; Karunanayake, L; Samarasekara, AMPB; Amarasinghe, DAS; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Structural, thermal, physical and mechanical properties of microcrystalline cellulose (MCC) combined with its biodegradability make an excellent platform for the aptness of MCC in reinforcing polymeric composites along with a commercial success in the context of green chemistry. Main drawback of above union is the incompatibility of hydrophilic MCC and hydrophobic polymers which ultimately damp the desired property improvements. With a prospective and pioneering a green approach, this study introduces a novel method to modify the surface of MCC to introduce surface hydrophobicity. State of the treatment was analyzed with acyl percentage, FTIR analysis, wettability test, SEM images and TGA thermographs. Results uphold the success of the transesterification reaction of sunflower oil ethyl esters (SFEEs) with MCC showing higher attraction to nonpolar dichloromethane with an improved thermal stability. FTIR showed the successfully grafted SFEEs onto MCC surface. Modified MCC can be used in the fabrication of polymeric substances in the process of improving its mechanical properties simultaneously under green chemistrybased approach.
item: Conference-Full-text
Development of a Rubber-Based Strain Sensor to Evaluate Vehicle’s Tire Performance
(IEEE, 2023-12-09) Venugopalavanithasan, K; Selvakumar, V; Weragoda, SC; Samarasekara, AMPB; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Safety of the vehicles and assistance for self-driving cars have become a predominant requirement in automobile industries. In a scenario it is often required to assess the tyre performance of vehicles. This study proposes an elastomeric strain sensor that can fulfil the requirement to assess the tyre performance. A rubber strain sensor works like a piezoresistive material in which electric properties change while changing the strain of the subject. The proposed elastomeric strain sensor is composed of a rubber composite based on natural rubber and electric conductive filler such as conductive carbon black and carbon nanotube. The carbon black filler network conformation changes during applied load. The rearrangement of the filler network happens while releasing the load. The optimum composition was selected for study considering conductive filler content 12phr and crosslink density, sulphur content 4phr that affects the sensor's performance. The sensor was designed considering the tyre deformation in the belt edge of the tread region, where it shows higher deformation. A circuit was suggested to detect the senor resistance variation to be imbedded on the inner surface of the vehicle tyre.
item: Conference-Abstract
Development of antimicrobial materials for food packaging applications
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Senarath, SMNS; Madushani, SPA; Samarasekara, AMPB; Amarasinghe, DAS; Sivahar, V
The rising demand to increase fresh food shelf life as well as the need of protection against foodborne diseases urged the development of antimicrobial food packaging. Nanomaterials have increasingly being used in food packaging applications in recent years due to their extraordinary properties when compared to bulk materials. Nanoparticles provide signi? cant antimicrobial properties in different environmental conditions. Nowadays, there is heighten attention in designing nano particles incorporated food packaging with the introduction of nanotechnology. Silver nanoparticles (AgNPs) based antimicrobial packaging is an innovative form of food packaging used to extend shelf-life of food and reduce the risk of pathogens. AgNPs are one of the most powerful antimicrobial agents which can be used for increasing shelf life of foods due to its capacity to eliminate infectious micro-organisms. The present research work is based on the preparation of silver nanoparticles incorporated coating for polymer based packaging components. Nano Silver impregnated cross-linked polyvinyl alcohol coating was synthesized and applied on the polymer surface. In this study, wettability of the polymer surface was enhanced by a UV treatment. Contact angle was measured to confirmation of the wettability. The adhesion of the coating to polymer was obtained as load required to peel off the coating. Optimum UV treatment time was selected by using contact angle measurements and load required to peel off the coating. Thermal degradation of cross-linked Nano silver coating was determined using thermo gravimetric analysis. Presence of silver nanoparticles in the coating was confirmed by Surface Plasmon Resonance (SPR) and Scanning Electron Microscopy (SEM). The nano silver incorporated polymer was tested for its biocidal action against model bacteria Escherichia coli using zone inhibition and food contain in nano silver coated containers. Developed nano silver incorporated polymer based food packaging products showed antimicrobial properties. This developed product can be used to improve the quality of the food and extend shelf life especially in food packaging applications.
item: Conference-Abstract
Development of biodegradable packaging materials using Polylactic acid (PLA) and locally extracted starch
Kaushalya, RANC; Dhanushka, MKDT; Samarasekara, AMPB; Weragoda, VSC
The main objective of this research is to develop a biodegradable packaging material based on Polylactic Acid (PLA) and locally extracted starch. PLA is a biodegradable and bioactive polymer derived from renewable resources. Starch is a biodegradable polymer that can be extracted from different types of plant-based materials such as cassava tubers. Starch was extracted from cassava tubers by crushing, blending and sedimentation processes. The extracted product was characterized by Fourier Transform Infrared Spectroscopic technique (FTIR). Experimental results indicated that 25 wt. % of starch could be extracted from the cassava that was tested. Biodegradable PLA and starch-based blends were prepared by adding starch as the main additive. Soil burial test was performed to analyze the biodegradability of the developed product. Weight loss in starch containing samples gradually increased with time during the soil burial test. Experimental results also indicated that biodegradability of the products increased as the starch content is increased. The mechanical properties such as tensile strength and elongation also decreased as the starch content increased. These results indicated that the addition of starch to PLA is a better method to increase the biodegradability of the PLA –starch blends.
item: Conference-Abstract
Development of cellulose based light weight polymer composites
(2017) Rajapaksha, LD; Saumyadi, HAD; Samarasekara, AMPB; Amarasinghe, DAS; Karunanayake, L
Polymer matrix composites are used in most of the engineering structures today. This type of composite consists of reinforcing materials in polymer matrix. There is an increasing demand for environmentally friendly reinforcing materials to reduce the cost of traditional fibers. Cellulose is a natural polymer material. Cellulose is used as filler for the reinforcement of polymer materials. Microcrystalline cellulose is a branch of cellulose. Objective of this research is to develop and characterize polypropylene and microcrystalline cellulose based composite. Silane surface modification technique was used to modify the cellulose surface. Surface modified cellulose was mixed polypropylene materials with different compositions. Physical and mechanical properties of the developed product were measured by tensile, impact, hardness, density and water absorption tests. According to the experimental results, there is a gradual reinforcing effect with increase of cellulose' concentration. Water absorption and hardness results showed increase of water absorption and hardness with increase of cellulose concentration. There is a gradual reduction of density of the develop product with increase of cellulose concentration. 5 wt% sample showed the lowest density value and weight reduction is about 13%. This type of composite can be used for light weight strstructure design especially in load bearing applications.
item: Conference-Abstract
Development of cellulose-based precursor solution for electrospinning technique
(Department of Materials Science and Engineering, University of Moratuwa., 2022-11) Basnayaka, BMCGK; Udeshini, AA; Samarasekara, AMPB; Amarasinghe, DAS; Abeygunawardana, AAGA
To electro-spin a polymer solution, certain specific conditions need to be met, for example, acetyl content (A) (38- 40%), degree of substitution (DS) (2.3-2.5), molecular weight(M) (30,000 100,000 gmol-1) solution system of CA 15w%, acetone 80w% and water 5w%. This study aimed to produce an electro-spinnable cellulose acetate precursor solution from raw cotton. This paper discusses the cellulose extraction process as well as the characterization process. The electro-spun cellulose acetate fibers are significantly crucial to high-tech product designs.
item: Conference-Abstract
Development of nano silver impregnated food packaging materials
(Department of Materials Science and Engineering, 2019-01) Samarasekara, AMPB; Amarasinghe, DAS; Madhushan, WKP; Chathuranga, SN; Sivahar, V; Sitinamaluwa, HS
The growing demand for increased shelf-hfe of food and the need for protection against foodbome diseases, fiiel the development of new food packaging materials. Silver-nanoparticle (AgNp) impregnated packaging materials are promising candidates for active food packaging. These active packaging materials are capable of extending the shelf-life of foods and reducing the risk of pathogens. The current research work is focused on the development of AgNp incorporated coating for polymer-based food packaging. AgNp dispersed in polyvinyl alcohol solution was prepared by in situ reduction method, in which silver nitrate and polyvinyl alcohol (PVA) acted as precursor and capping agent respectively. Presence of silver nanoparticles in the solution was confirmed by photoluminescence spectroscopy and UV-Vis spectroscopy. In order to reduce coating solubility PVA solution was cross-linked. The compatibility of the coating with the substrate was enhanced by plasma treatments. Contact angle measurements were employed to monitor the wettability changes. The solubility of the coating was examined by gravimetric methods. The effects of cross-linked temperature and cross-linked agents on solubility were studied. The presence of silver nanoparticles in the coating was confirmed by surface plasmon resonance and electron micrographs. The modified Kirby-Bauer (disk diffusion) method was employed to measure the anti-bacterial effect of the coating.
item: Conference-Abstract
Development of polylactic acid (PLA) based biodegradable packaging materials
(Department of Materials Science and Engineering, 2019-01) Dhanushka, MKDT; Kaushalya, RANC; Samarasekara, AMPB; Sivahar, V; Sitinamaluwa, HS
The key purpose of packaging is to protect the contents or products from external factors. Synthetic polymers do not degrade completely in nature after the usage and create environmental issues. Therefore, there is a tendency to substitute such polymers with natural polymers that are easily biodegraded and less likely to cause environmental pollution. The main objective of this research is to develop a biodegradable packaging material based on Polylactic Acid (PLA) and locally extracted starch. Starch was extracted from cassava tubers by crushing, blending and sedimentation processes. The extracted product was characterized by Fourier Transform Infrared Spectroscopic technique (FTIR). Experimental results indicated that 25 wt.% of starch could be extracted from the cassava that was tested. Biodegradable PLA and starch-based blends were prepared by adding starch as the main additive. The dried starch was incorporated into the PLA and melt-blended using laboratory scale internal mixer. A mixing process was performed for various starch concentrations. The blended samples were then pressed to form thin sheets in a hydraulic press. Soil burial test was performed to analyze the biodegradability of the developed product. The tensile strength and elongation at break of the samples were determined by tensile testing. Weight loss in starch-containing samples gradually increased with time during the soil burial test. Experimental results also indicated that biodegradability of the products increased as the starch content is increased. The mechanical properties such as tensile strength and elongation also decreased as the starch content increased. These results indicated that the addition of starch to PLA is a better method to increase the biodegradability of the PLA -starch blends. These developed biodegradable materials can be used as a sustainable material to create safer environment.
item: Conference-Abstract
Development of shape memory polymer for high temperature applications
(Department of Materials Science and Engineering, University of Moratuwa., 2023-07-28) Koralage, CR; Srilal, TAB; Samarasekara, AMPB; Sivahar, V
Cyanate ester (CE) based polymers are well known for aerospace and microelectronic applications due to their unique characteristics at higher temperatures. Due to the cyanurate network formed during the curing process, cyanate ester-based shape memory polymers have resistance to harsh environment conditions. Furthermore, the shape memory behaviour of CE based resins allows them to be a suitable candidate for high temperature applications which require shape memory effect. This study investigates the shape memory behaviour of bisphenol-A-cyanate ester (BACE) cured with polyethylene glycol (PEG) with five different ratios. The formation of cyanurate has been confirmed by the Fourier transform infrared spectroscopy (FTIR) analysis. The thermal stability of the developed material was confirmed using the Differential Thermal Analysis (DTA)/ Thermogravimetric analysis (TGA). It was confirmed that thermal stability remains up to 350 C0. The shape memory behavior was successfully performed by the polymer with shape memory bending test. The modified resin with higher PEG ratios indicates higher shape recovery ratios whereas the resins with lower PEG ratios exhibit higher shape fixity ratios, tensile strengths, and hardness values. Using PEG as the switching segment, CE based resins can be used for high temperature shape memory applications and can be modified to obtain certain properties according to the PEG ratios.
item: Conference-Full-text
Direct current resistivity based in-situ cure monitoring technique for amine cured epoxy resins
(IEEE, 2022-07) Herath, HS; Janith, GI; Weragoda, VSC; Amarasinghe, DAS; Attygalle, D; Samarasekara, AMPB; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The Epoxy resins and epoxy resins-based system usage in industrial applications such as composites and electronic materials keep growing. Thus, research focused on enhancing the properties of these resin-based systems is of importance for manufacturing quality controls. Especially monitoring of cure progression and chemo-rheological behavior of epoxy resins are essential for many industries. Commonly practiced cure monitoring methods such as DSC and DMA for the purpose are conducted in laboratories under specified conditions and are not practiced for real-time cure monitoring. However, in-situ cure monitoring techniques are essential for many industries as they provide more insight and thus more control over processing parameters. This study introduces a direct current resistivity-based cure monitoring method as it is simple, cost-effective, reliable, and more importantly, industry-friendly. The fast response of direct current measurements combined with the simplicity of the analysis makes this method suitable for real-time sensing applications. The strong correlation between the degree of cure and the viscosity allows us to take simultaneous measurements of both. The method's feasibility was analyzed using two amine cured epoxy resin systems.
item: Conference-Full-text
Effect of annealing on temperature coefficient of resistance of cu-ni foil as strain gauge material
(IEEE, 2023-12-09) Satheekshana, W; Weragoda, SC; Amarasinghe, DAS; Samarasekara, AMPB; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
Near zero Temperature Coefficient of Resistance (TCR) is an increasing concern in the strain gauge manufacturing industry. The purpose of this study is to investigate the connection between the TCR of the Strain Gauge (SG) and the annealing temperature of the foil used to manufacture the strain gauge. Constantan foils were heat treated, under a nonoxidizing annealing environment. The TCR of the manufactured foil-strain gauges were calculated in the range of -10°C to 40°C. The TCR values were shifted from negative to positive with annealing temperature. This study provides a conclusive response to the question concerning the effect of annealing temperature of Constantan foil for the manufacturing of strain gauges with near zero TCR.
item: Conference-Extended-Abstract
Effect of deacetylation conditions on synthesis of chitosan using shrimp type "penaeus monodon"
(2011) Adikary, SU; Samarasekara, AMPB; Unagolla, JM; Wijesinghe, WARP
In this study synthesis of chitosan from shrimp type penaeus monodon and effect of degree of deacetylation conditions were studied. Chitin was extracted from shrimp shells and deacetylation process was done to synthesize chitosan under different conditions. Characterization of the synthesized chitosan was done using Fourier Transmission Infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The effect of NaOH concentration, reaction temperature, and reflux time on the deacetylation process was investigated. Degree of deacetylation of chitosan was determined using infrared spectroscopy technique. Mainly, the increasing of NaOH concentration, temperature, number of deacetylation time and reflux time can enhance the degree of deacetylation (DD) of chitosan.
item: Conference-Abstract
Effect of Papain on the biodegradability of polyethylene modified by Chitosan
(2008) Samarasekara, AMPB; Gunapala, PY
The objective of this research was to impart biodegradability to polyethylene. Chitin and Chitosan were main additives extracted from the fishery waste. Chitosan, a natural polymer, was one prospective contender for imparting biodegradability to Polyethylene. Papain a natural enzyme was used in addition to enhance biodegradability. The biodegradability of Polyethylene blend was studied using low molecular weight chitosan in the presence and absence of papain. The soil degradation test was performed to evaluate degree of biodegradability. Results obtained showed that specimens buried in the soil were degraded by almost 60% after six months 1.vhen papain was added and the test sample was completely disintegrated after one year. The combinations of chitosan, papain and polyethylene showed the appreciable biodegradable properties of Low Density Polyethylene products after industrial and domestic applications.
item: Conference-Full-text
Effect of particle size distribution of rice straw on cellulose extraction
(IEEE, 2020-07) Ratnakumar, A; Samarasekara, AMPB; Amarasinghe, DAS; Karunanayake, L; Weeraddana, C; Edussooriya, CUS
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 which can be employed in various industrial applications. 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 with half of the world population consuming it as the major food source. Chemical extraction and purification 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. In this research, effect of particle size distribution of locally available rice straw on cellulose synthesis was studied. Study revealed that after the series of chemical treatments M-75 yielded 27.19 ± 0.98 percent, M-250 yielded 38.31 ± 0.86 percent and M-H yielded 33.68 ± 0.68 percent cellulose. FTIR analysis revealed the sequential and complete removal of lignin (1516 cm−1, aromatic skeletal vibrations), hemicellulose (1729 cm−1, carbonyl stretching) and silica (796 cm−1, Si–O–Si stretching) thus, confirms the final product as cellulose. SEM images showed that M-75 exhibited whisker like structure whereas M-250 showed fibrillar network structure. These findings will have profound influence upon extracting cellulose from agricultural biomass.
item: Conference-Abstract
Exploring the value addition potential of the local rice straw varieties
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Nanayakkara, MPA; Pabasara, WGA; Samarasekara, AMPB; Amarasinghe, DAS; Sivahar, V
Polymers play a critical role in engineering applications today. Cellulose is the most abundant renewable natural biopolymer on earth. It is present in a wide variety of living species including plants and some marine animals. Rice is the main food of the inhabitants of Sri Lanka. The total land devoted for paddy is estimated to be about 708,000 hectares at present in Sri Lanka. Rice straw is a rice by-product produced after harvesting paddy. Rice straw is a major agricultural waste product in Sri Lanka. There is no effective value addition to local rice straw today. Rice straw contains considerable amount of cellulose with hemicelluloses and lignin. This research is based on investigating the possibility of extraction of cellulose from most frequently used traditional rice varieties (Suwandel and Raththal) and technically modified rice varieties (BG300 and BG352) in Sri Lanka. The dried and cleaned rice straw was milled using a grinder to produce fine powder of rice straw. Sieve analysis method was used to analyze the rice straw powder and equal or less than 150 ? m particle size was selected for the cellulose extraction. Pure cellulose was extracted from BG 352 rice straw variety after following de-waxing, deligni? cation, hemicellulose and silica removal processes. Same extraction procedure was followed for BG 300, Suwandel and Raththal rice varieties. The complete removal of non-cellulosic materials from rice straw was confirmed by FTIR spectroscopy after each chemical purification step. According to the experimental results, highest cellulose yield was obtained from rice straw of Suwandel (35.2%). Other types of rice varieties showed cellulose yield of BG300 (27.8%), BG352 (29.3%) and Rathhal (26.8%). Key feature of this research is developing new processes and technologies to convert Sri Lankan agricultural waste into value - added product of cellulose. These extracted cellulose material can be used for different engineering applications.
item: Conference-Full-text
Extraction and characterization of cellulosic fibers from sawmill waste
(IEEE, 2016-05) Kahawita, KDHN; Samarasekara, AMPB; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
In the current period of time synthetic polymers are rapidly spreading among people due to the advantages of advanced mechanical properties with low cost and weight. However, due to the low biodegradability, synthetic materials produce environmental pollution. Therefore the productions of biodegradable materials are playing a major role to save the environment. All natural materials are biologically degraded by the actions of micro-organisms in the environment. The biomass is mainly consists of cellulose, hemicellulose and lignin and they are the most abundant biopolymers present on the earth. Out of the three biopolymers cellulose and hemicellulose have comparatively high biodegradability due to the polysaccharide structure. Sawmill waste is one of the major waste with lack of attention in Sri Lanka. Therefore, the research is focused to produce low cost, biodegradable composite material for engineering applications by extracting cellulosic materials present in sawmill waste. For the study, separately collected five common timber samples and the mixture of each (equal mass of five most common wood wastes) were used. Finally, it concludes that the maximum percentage of cellulose and hemicellulose can be extracted from the waste wood mix sample (68. 7%) and the extracted natural polymers were characterized using FTIR analysis.
item: Conference-Abstract
Extraction and characterization of Nano Crystalline Cellulose (NCC) From Sri Lankan agricultural waste
Wickramasinghe, WAWIC; Lasitha, DS; Samarasekara, AMPB; Amarasinghe, DAS; Karunanayake, L
In this research synthesis and characterization of cellulose and nano cellulose and process run under several conditions to obtain parameters which are belongs to optimizing. Cellulose was extracted from BG 352 rice straw using de-waxing, delignification, hemicellulose and silica removal treatment. Extracted cellulose was characterized by Fourier transform infrared spectroscopic techniques (FTIR). SEM image showed that isolated cellulose fibers with diameter ranging from 2-8μm and yield of extracted cellulose are around 21%. Nanocellulose is the material at least one dimension in the nano meter range. The cellulose contains some amorphous regions as well as crystalline regions and by treating some strong acid such as sulfuric to broken up the cellulose from amorphous region. The resultant product is nanocellulose. Nano crystalline cellulose can be obtained from plant matter which comprises nano sized cellulose material. Nano crystalline cellulose synthesis was followed using cellulose by acid hydrolysis, quenching, centrifugation, dialysis, sonication, freeze drying process in this research. So locally available rice straw is a source to synthesize the nano crystalline cellulose.
item: Conference-Abstract
Extraction and modification of chitosan from fishery waste to develop biodegradable polyethylene films
(2006) Gunapala, PY; Samarasekara, AMPB
Polymers made of petroleum by products have come into wide use throughout the world. With an increase of their applications, the treatment of waste polymers has become a serious environmental problem because of the difficulty of ensuring refilling land and burning. The principle methodologies of waste management of polymer based products are mechanical recycling, incineration and biodegradation. Mechanical recycling and incineration have technological and ecological limitations but biodegradation is an environmental friendly economical process compared to above two methods. Conventional polyethylene products can take longer than 100 years to degrade, but a biodegradable product has the ability to break down, safely and relatively quickly, by biological means, into the raw materials of nature and disappear into the environment. Therefore these polymers can be considered as a solution for the plastic waste disposal problem.