MESII - 2017

Permanent URI for this collectionhttp://192.248.9.226/handle/123/17181

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Now showing 1 - 20 of 22

item: Conference-Abstract
Development of a low cost, static light scattering based nano-particle size analyzer
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Anuradha, SKA; Ishan, HHA; Amarasinghe, DAS; Sivahar, V
A machine based on Static Light Scattering theories was developed for the cost effective and efficient Quality Control of the average particle size of nano-particles used in different manufacturing industries. In particular the instrument was adapted to measurement of carbon black filler used in rubber compounding. Carbon blacks are amorphous quasi graphitic particulates of the nanometer scale whose mean particle size affects the reinforcement, conductivity pigmentation and UV resistance properties of the rubber. The instrument would enable local rubber compounding companies to independently monitor and control the average particle size of the filler. The system is semi-autonomous and measures approximately 29cm × 23cm × 17.5cm and weighs approximately 4.2 kg. The instrument accepts a solution of nano-particles. Adjusts the solution concentration automaticallyand measures the scattered intensity of light which it used to calculate the particle size. The system comprises of a fluidics module that handles the pumping and dilution of solutions, an optics module that generates and detects the light and a control & power supply module that operates the other components and supplies the right voltages to them. These modules are housed in a corrosion protected steel frame and an aesthetically appealing enclosure. Key features of the instrument are a self diagnostic system, a modular structure, a graphical user interface with record keeping facility and extendibility to other particle size control applications. It is of a modular design and has been constructed with the ease of maintenance and accessibility to internal hardware, and manufacturability in mind. The components selection was based on the optimization of performance parameter, size and cost. Mechanical, thermal and vibration stabilities were considered in the design.
item: Conference-Abstract
Design of a Dynamic Mechanical Analyser for Rubber Compounds
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Herath, HMRC; Rodrigo, IJ; Weragoda, VSC; Sivahar, V
Dynamic mechanical analysis (DMA) is a powerful technique for characterization of the viscoelastic properties of polymers such as thermoplastics, composites, thermosets and elastomers in the form of sheet specimens, films, fibers, coatings or adhesives. DMA instruments measure the modulus (stiffness) and damping (energy dissipation) properties of materials as they are deformed under dynamic stress. When a polymeric material is subjected to a cyclic sinusoidal stress within the viscoelastic region, the corresponding strain in the material would be out of phase due to the delayed response of the viscous portion of the material. This phase difference corresponds to the frequency of the force application and this is a unique characteristic of the polymer material. Amplitude of the strain curve and phase shift between stress and strain curves are usually identified as basic parameters. In this design which is based on the ISO 6725 standard, forced vibration method was used and the vibrations are impacted by the inertia force of an eccentric rotating mass is used to generate sinusoidal force. Multi stress and multi frequency modes are operated by adjusting eccentricity and speed of rotating mass. The instrument also has facility to adjust the static force imparted on the specimen. Deformation of the material is detected by a displacement sensor. This design satisfied all requirements of the testing standard.
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 CZTS based solar cell
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Dilshan, HADI; Weerasinghe, WDD; Attygalle, D; Sivahar, V
The two semiconductor layers Cu2ZnSnS4 (CZTS) and CdS were successfully fabricated using economical, solution-based fabrication techniques. CZTS thin film fabrication was done by spin coating technique onto soda-lime glass substrates at rotating speed of 2000 to 6000 rpm. It was found that the optimum precursor solution temperature is 38 o C-42 o C. The films dried at 140 o C-160 o C and annealed in air at 280 o C have shown a band gap in the range of 1.45 to 1.55eV. Cadmium Sulfide (CdS), the n-type semiconductor heterojunction partner for CZTS was also deposited with good thickness control and uniformity in the range of 50-100nm range. Chemical bath deposition method was utilized for CdS thin film fabrication and the CdS thin film with optimum properties was obtained at the conditions of 40 o C-45 o C temperature range and thickness variations were also apparent with the number of coatings applied and the fabrication time. The annealing temperature was found to be critical within the range of 180 o C-220 o C (30 mins) for the optimization of CdS bandgap. CdS thin film fabricated under optimum conditions has shown a bandgap range of 2.30eV-2.50eV. Successful deposition on Fluorine doped Tin Oxide (FTO) glass substrate, reveals a feasible route to fabricate superstrate type photovoltaic cell.
item: Conference-Abstract
Development of metal oxide based solid state gas sensor platform
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Udaraka, MPSD; Nanayakkara, HATV; Attygalle, D; Amarasinghe, DAS; Sivahar, V
Gas sensors are chemical sensors which have a transducer and an active layer for converting the chemical information into another form of electronic signal. Gas detection and determining the composition of a gas in a mixture is necessary in many different fields. In this research, development of metal oxide based sensing material layer and design of sensor platform were on focus. SnO2 was selected as the main precursor of the sensing material and Mn as the dopant. Material deposition was done by spin coating method on soda lime glass substrate. The complete platform consists of sensor material, heating element, temperature monitoring and control unit, Arduino board for data acquisition and signal processing. The temperature dependence of resistivity of SnO2 film was studied in detail in the presence of different gases and gas mixtures. The results shows that the Mn doped spin coated SnO2 thin film is a promising method for the preparation of high quality ethanol sensor even in a mixture of ethanol and acetone. Optimum sensitivity for ethanol was obtained at 140 0 C - 160 0 C temperature range.
item: Conference-Abstract
Development of spark emission spectrometer to identify an alloy
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Gunerathne, MGGM; Karunasena, DBTK; Attygalle, D; Amarasinghe, DAS; Sivahar, V
Spark optical emission spectrometer (OES) is a widely used technique in identifying alloy compositions of metals. Based on the OES principle, a low-cost spark, portable and fully automated spark optical emission spectrometer was developed. A 1000kV ultra-high voltage arc generator coil module was used as the excitation source and a CMOS (complementary metal-oxide semiconductor) image sensor was used as the spectral detector in this spark OES. Data collection and interfacing was done through a Raspberry Pi Single-board Computer. Analysis of wavelength and intensity data were performed using an algorithm coded in python programming language. The program presents the alloy elements and their quantities. Three main factors that limits the precision and accuracy of results were identified as the excitation source, the resolving powers of the spectrometer and the electronic noise characteristics of the systems.
item: Conference-Abstract
Fabrication of dye sensitized solar cells using locally available sensitizers
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Samanchandra, MHAR; Tharanga, WADD; Galhenage, AS; Sivahar, V
Dye sensitized solar cells (DSSCs) are the one of the most promising third generation solar cells which based on mesoporous nanocrystalline titanium dioxide and organic dyes. DSSCs provide a technically and economically reliable alternative concept for current silicon based photovoltaic solar cells. In this study, DSSCs were fabricated using the dyes extracted from locally available natural plants of mangosteen, centella, beetroot, and turmeric. Extracted dyes were analyzed using UV-vis spectrometer. Photo anodes were prepared using regent grade TiO2 powder. The TiO2 films were coated on fluorine doped tin oxide glass substrates using doctor blade method and spray coating method. The film quality was examined using X-ray diffractometer and scanning electron microscope. The film prepared using spray coating method has better uniformity. DSSCs fabricated using the dye extracted from mangosteen have shown high efficiency than the DSSCs of other dyes. Two dyes were mixed; namely, dye X (a mixture of dyes from mangosteen and centella) and dye Y (a mixture of dyes from mangosteen and turmeric), and adsorptions of dyes from the mixtures were employed to enhance the solar cell efficiency by enhancing the light absorption range. The DSSCs fabricated with mangosteen and turmeric combination of dyes yielded the maximum performance.
item: Conference-Abstract
Evaluation of potential of two natural polymers in enhancing physical properties of silica filled natural rubber latex films
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Rajasekara, RWDHS; Randeepa, HPDK; Liyanage, NMVK; Sivahar, V
The applicability of two natural proteins; zein and soy, extracted from corn and soya respectively, as surface modifiers for silica to be used in natural rubber latex(NRL) compounds was investigated. Two proteins were extracted by affecting some minor modifications to two established processes. Surface modification of silica with the extracted proteins was affected, in-situ, separately in aqueous media while the preparation of silica dispersions. The modified silica was characterized by FTIR spectroscopy. Physical properties of modified silica incorporated NRL films cast from NRL compounds prepared following a standard formula were measured as per the relevant standards. FTIR spectroscopy confirms the surface modification of silica caused by added proteins. The dispersion stability of modified silica dispersions was observed to be better than that of unmodified silica. Distribution of modified fillers in rubber matrix was found to be better than that of unmodified filler. Both types of modified fillers were found to be capable of enhancing tensile properties of NRL films to different extents with marginal effects on tear properties.
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-Abstract
Improve the locally manufactured billets after homogenizing to match with imported billets
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Sankalpa, PVG; Welathanthri, SL; Guluwita, SP; Sivahar, V
6xxx series aluminum alloys have a combination of medium strength, good corrosion resistance, excellent formability, good weldability, easy recycling and especially good heat treatability. AA 6063 alloy is the most widely used of all extruded Aluminium alloys. The processing of AA 6063 billets always starts with a homogenization cycle since the homogenized billets are extruded easier and faster and gives better surface finish as well as good mechanical properties than as-cast billets. Homogenization is the creation of a homogeneous (uniform) structure in alloys by getting rid of concentrated micro irregularities formed in alloys during crystallization, diffusion metal spraying, and so forth. This study aims to improve mechanical properties of the AA 6063 aluminum alloy produced by the vertical continuous casting method. The imported billets were taken as reference samples. For this purpose, the billets were heat treated at different temperatures changing the soaking time. Specimens at each group were exposed to microstructure analyses and hardness tests in order to determine their mechanical properties. For microstructure analysis was done using both optical and scanning electron microscopes. According to the analysis, it was determined that the mechanical properties depending on casting temperature and heat treatment cycle. It was found that, at 580 o C – 8 hours is optimum heat treatment cycle and the 690 o C is the best casting temperature.
item: Conference-Abstract
Investigation of applicability of coconut shell powder as a filler in natural rubber composites
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Athauda, AARS; Chathuranga, G; Liyanage, NMVK; Sivahar, V
Applicability of coconut shell powder(CSP) as a filller in natural rubber(NR) based composites was investigated. Incorporation of CSP into NR composites was done in two different forms; crude CSP, purified CSP, either with or without a coupling agent(silane). Two series of NR compounds containing 80phr of filler were prepared. The compounds of the first series was prepared by varying the carbon black content from 0-80pphr with no CSP present. In the second series the ratio of carbon black/CSP was varied from 80/0 to 20/60. The first series used as the reference series. NR composites filled with different forms CSP separately were compared with equivalent composites filled with carbon black. The processing characteristics and the curing behavior of the composites were determined by Gottfert rheometer. The mechanical performances of the vulcanisates were determined by analyzing their tensile strength, tear strength, hardness, resilience and abrasion resistance. Replacement of carbon black with CSP in NR compounds was found to improve certain properties like hardness, elongation and resilience of resultant vucanisates when present in low concentrations. Overall performance of purified CSP was found to be better than that of crude CSP. The use of silane as a coupling agent slightly improved the properties of the vulcanistes.
item: Conference-Abstract
Investigation of laser scribing technique for graphite oxide reduction and patterning
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Prasath, M; Jayasinghe, JGDSD; Attygalle, D; Sivahar, V
Engineering a low cost graphene-based electronic device has proven difficult to accomplish via a single-step fabrication process. An infrared laser assisted technique to reduce graphite oxide (GO) to graphene, at ambient conditions, was studied in detail. The GO films for this study were fabricated using the modified Hummer's method. The raw materials used for this project was Sri Lankan vein graphite. The GO films were deposited on flexible polymer substrate. The laser scribing technique is shown to be successful in reducing GO, and also patterning of graphene. The FT-IR spectra before and after laser exposure have confirmed the reduction GO. In addition, by varying the laser intensity and laser irradiation time, the resistivity of the material can be precisely tuned over 5 orders of magnitude from 7.5 ×10 6 Ωm to 14.1 Ωm.
item: Conference-Abstract
Development of natural fiber-plastic composite using jute fiber and epoxy resin
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Kumara, PKSP; Dharshana, WMTS; Udayakumara, SV; Sivahar, V
In modern world, fiber reinforced plastics play a dominant role. The fiber which serves as a reinforcement in composite may be synthetic or natural. Although synthetic fibers (ex. Glass, carbon, etc..) posses higher mechanical properties, their applications are limited due to high cost and health issues . Natural fibers are generally cheaper than the synthetic fibers. The present study describes the development of a natural fiber - plastic composite consisting of jute fiber as reinforcement in epoxy resin. Experiments are carried out to study the effect of fiber volume and length on mechanical behavior of these epoxy based composites. Composites prepared with random fiber orientation and average fiber length varied from 1cm to 6cm.Variation of modulus of rupture (MOR), tensile strength and Impact strength were studied with varying fiber length. Also studied the effect of fiber volume on MOR, tensile strength, impact strength and hardness of composite by varying fiber volume fraction from 4% to 12 % for fibers with 5cm average length. Composite with 10% jute fibers showed highest values of MOR 5.1 MPa, tensile strength 567.1 MPa and Impact strength 7.2 kgcm
item: Conference-Abstract
Microcrystalline cellulose based polymer composite for engineering applications
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Rajapaksha, LD; Saumyadi, HAD; Samarasekara, AMPB; Amarasinghe, DAS; Sivahar, V
In the last several years, polymer composites have been used heavily in aerospace, automotive and other engineering applications. Polymer matrix composites (PMCs) are comprised of a variety of short or continuous fibers bound together by an organic polymer matrix. Natural fibers are recently getting attention from researchers and academia to utilize in polymer composites due to their ecofriendly nature and sustainability. Cellulose is the most abundant and renewable biopolymer on earth and is obtained from renewable resources such as biomass. Microcrystalline cellulose (MCC) is a member of cellulose family. MCC possesses many advantages compared to cellulose fibers. Polypropylene is one of the widely used thermoplastic material as matrix material in engineering applications. In this research, Polypropylene matrix with microcrystalline cellulose reinforced composite was investigated for their mechanical properties. MCC was subjected to surface modification to improve compatibility with hydrophobic Polypropylene using silane treatment. Polypropylene was mixed with surface treated MCC by varying MCC concentration (1% wt. to 5% wt.) in a laboratory type internal mixer. Composite was fabricated using compression moulding technique. Impact, tensile, hardness and water absorption tests were performed to evaluate the mechanical properties of the developed composites. Density of the developed composite was measured to estimate the weight of the developed composite. Experimental results showed that gradual increase of tensile strength, hardness and impact strength with the increase of MCC concentration. Polypropylene with 4 wt% of MCC. sample showed the maximum impact strength and it was 18.2 KJ/m 2 . Maximum water absorption (0.02%) was observed in 5wt%. MCC containing sample. 5wt%.MCC containing sample showed a maximum hardness (74.5 Shore D). Developed composite showed the gradual reduction of density from 1wt% MCC (0.880 g/cm 3 ) to 5wt% MCC (0.825 g/cm 3 ). Therefore, Polypropylene with MCC polymer composite can be used for different engineering application. This provides light weight benefits.
item: Conference-Abstract
Solar powered mini air conditioner for automobiles
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Gunawardhana, HPB; Chamath, LG; Galhenage, AS; Sivahar, V
As a tropical country, Sri Lanka experiences sunny conditions throughout the year. Most of the time vehicle users find it difficult to obtain shady places for their parking purposes. The temperature rise of the automobiles parked in sun is a critical issue which creates uncomfortable feelings for the passengers. Here we develop an affordable mini air conditioning system for the automobiles. The heat buildup in inside of the vehicle is fully investigated and the energy requires for cooling is also estimated. Solar energy is the most effective renewable energy source for countries like Sri Lanka. In this study, sustainable solar energy is used to maintain the vehicle inside temperature during the parking. Our design project is based on the photovoltaic system and the comfortable temperature is created by using a solar powered mini air conditioner. Our finding provides an attractive solution for this uncomfortable situation. Furthermore, the result of this study can be used by heating ventilating and air conditioning engineers to design more efficient air conditioning systems for different applications.
item: Conference-Abstract
Nondestructive evaluation of corrosion damage in concrete reinforcement bars
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Maddumahewa, KK; Madusanka, NPA; Sivahar, V; Sivahar, V
Corrosion of reinforcement bars which are embedded in concrete is one of the significant problems encountered in reinforced concrete structures. Despite the fact that concrete gives protection against corrosion, aggressive environmental conditions can lead to the corrosion of the reinforcement bars embedded in concrete. This may affect the strength of the concrete structures which leads to catastrophic failures during the service. Assessment of the extent of corrosion in embedded reinforcement bars nondestructively is the main objective of this research work. Grade M30 concrete mixture was used for the preparation of rectangular square blocks as testing samples. Concrete specimens with embedded steel bars of 10 mm, 16 mm, 20 mm and 25mm diameters have been subjected to accelerated corrosion using ‘Impressed Current Technique’ for different time periods. The ultrasonic velocities through the concrete samples with corroded reinforcement bars were measured against the corrosion time and the bar diameters. For these measurements Portable Ultrasonic Nondestructive Digital Indicating Tester (PUNDIT) was used. The weight loss due to corrosion of the reinforcement bars were measured subsequently, and those readings were evaluated against the ultrasonic velocities. The ultrasonic velocity decreases with the time and the extent of corrosion.
item: Conference-Abstract
Development of composite material based on waste paper and waste LDPE for ceiling sheets.
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Pathirage, TG; Munasinghe, DKR; Udayakumara, SV; Sivahar, V
In Sri Lanka used papers are re-utilized only for paper and board industry. However ,collecting used papers and recycling them are still highly inhomogeneous. Therefore major part of used papers become garbage. Used plastics are another agent that produce many environmental issues. Major part of waste plastics consist low density polyethylene (LDPE) which is mostly used for packaging items. This study was aimed to develop light weight composite material based on waste paper and waste LDPE specially for ceiling sheets. Use of waste as a starting materials for composite will contributes to savings of natural materials, reduction of energy and chemicals consumption, reduction of the impact on fresh water and improvement of waste management strategies. The composites with various compositions were prepared by hot compression moulding by varying weight percentage of paper and LDPE. . Tensile strength, modulus of rupture, hardness, thickness swelling, linear swelling , water absorption and thermal conductivity were determined for all compositions according to the ASTM standards. According to the test results water absorption and swelling gradually increased. However all the composite samples showed less thermal conductivity , less density and better mechanical properties than asbestos which is the mostly used material for ceiling sheets. Therefore in future paper based composites will become a cheaper replacement for ceiling materials.
item: Conference-Abstract
Rubber based strain sensor for detection of tyre and road conditions
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Karunarathna, NPM; Sivahar, V
Detection and measuring of larger strains as those exist in rubber components has long been a requirement that had met with limited success. Compared to traditional metallic strain gauge, elsatomer based strain sensors would be more durable in situations where strains are larger and not uniaxial, as those exist in automotive tyre walls and rubber springs. Detecting road conditions or the health of the tyre using a sensor mounted on the surface of a tyre wall is a possibility that opens up a number of possibilities with regard to vehicle safety. When a normally electrically non conductive polymer is partially filled with a conductive filler, the electrical conductivity of the polymer increases, proportionate to the filler content. However, when a strain is applied, conductive path will be disturbed due to redistribution of the filler and the electrical properties will be changed. This phenomenon has been used as the sensing mechanism of this sensor. Nitrile rubber has been used as the base material for the sensor while carbon black was used as the active filler. The concentration that initiate continuous electrical conductive path is called the percolation threshold concentration. Sensing part was developed using the threshold concentration as a guideline to maximize the sensitivity to the strain. The sensing part that would be applied in inner surface of vehicle tyre would be stretched when a the tyre flexes due to uneven road surfaces or incorrect inflation. An electronic circuit detects the resistivity variation in sensing part which is representative of the flexing of the tyre according to the shocks on vehicle tyre. The detected signal needs to be decoded to its source. The experimental results on the performance of the sensor indicated extremely large changes in electrical conductivity of the sensor within a short span of strain which is preceded and succeeded with a region of strain having a moderate sensitivity. One of the observed drawbacks of the sensor was its relatively high recovery time.
item: Conference-Abstract
Preparation of wood-plastic composite using teak saw dust and high density polyethylene
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Wimalaratne, BAPM; Madushan, WKR; Udayakumara, SV; Sivahar, V
Wood-Plastic composites are materials made out of wood (Fibers, particles. dust, etc..) and thermoplastic materials (PP, LDPE, HDPE, etc...). From Recent history wood-plastic composites have an increase in popularity due to their better properties than conventional wood based materials like hard board, plywood, etc... These wood-plastic composites have various applications including particle boards and ceiling sheets however cost of these composites are generally high. Therefore this study was aimed to develop an affordable composite material using locally available saw dust and waste high density polyethylene as thermoplastic material which is one of the main plastic waste Sri Lanka. Teak saw dust was selected as a type of saw dust due to its higher availability in Sri Lanka. The composites with various compositions were prepared by hot compression moulding at 150 °C by increasing the percentage of saw dust from 30% to 70% by weight. Tensile strength, modulus of rupture, hardness, thickness swelling and water absorption were determined for all compositions according to the ASTM standards. The results showed highest tensile strength at 70/30 weight % HDPE/Saw dust content and highest modulus of rupture at 40/60 weight %. Also results showed that hardness of the composites increased with increasing saw dust percentage while water absorption and thickness swelling decreasing. But water absorption and thickness swelling of all compositions were much better than the Plywood and hard boards.
item: Conference-Abstract
Study of the dielectric behavior of graphite oxide upon exposure to chlorine
(Society of Materials Engineering Students, Department of Materials Science and Engineering, University of Moratuwa, 2017-03) Silva, SM; Kulathilake, PHD; Attygalle, D; Amarasinghe, DAS; Sivahar, V
Graphite Oxide (GO) was synthesized using the Improved Hummer’s Method. After the successful synthesis of GO, it was characterized and its dielectric properties were investigated. The change of dielectric behavior of GO upon exposure to chlorine gas (Cl2) was studied. The obtained data were then analyzed to determine the mechanism by which the dielectric properties change. It was established that the gas physisorption is a two step process of which, one process has linear dependence with time while the other process modeled according to the Langmuir isotherm model. Finally the FT-IR spectra of the material before and after being exposed to Cl2 gas were compared to understand the changes made to the material.

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