MESII - 2020

Permanent URI for this collectionhttp://192.248.9.226/handle/123/17183

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item: Conference-Abstract
Materials Engineering Symposium on Innovations for Industry 2020 (Pre Text)
(Department of Materials Science and Engineering, University of Moratuwa., 2020) Abeygunawardana, AAGA
item: Conference-Abstract
Influence of low-amplitude high-frequency pulsed current on the deformation characteristics of low and medium carbon steels
(Department of Materials Science and Engineering, 2020-02) Hendeniya, HMND; Shiranga, WMP; Abeygunawardane, AAGA; De Silva, GIP; Abeygunawardane, AAGA
When electrical pulses are applied to a metal during deformation, the resistance to deformation is dramatically reduced while the plasticity increases significantly. This phenomenon is introduced as electroplasticity. Macroscopic observations of yield stress reduction under current pulsation due to uniaxial tension, creep and stress relaxation is in the center of attention recently. Traditional manufacturing processes such as drawing, and rolling be contingent on the use of heat to reduce the forces associated with the fabricated parts. The high-temperature requirement is potentially leading to stress, warpage, and reduced tolerance control. Therefore, Electrically Assisted Manufacturing is introduced as an effective way of simplifying the fabrication while enhancing end- product properties. The electroplastic deformation of low and medium carbon steels under uniaxial tensile conditions were investigated with respect to the universal uniaxial tensile testing conditions. A significant reduction of yield stress of low and medium carbon steel with different carbon content were observed due to electroplasticity effect. A qualitative and quantitative analysis of yield stress reduction was carried out. Microstructural behavior and morphological aspects of fractured and strained surfaces of low and medium carbon steel specimens were observed. Keywords: Electro plasticity, Electron wind force, Dislocations, Uniaxial tensile test, Electrically assisted manufacturing, Low and medium carbon steel, Plasticity
item: Conference-Abstract
Synthesis and morphological characterization of TiO2 nanotube arrays
(Department of Materials Science and Engineering, 2020-02) Rajapakse, HD; Rathhnayaka, VWSG; Sitinamaluwa, HS; Jayasundara, DRT; Abeygunawardane, AAGA
TiO2 nanotube arrays have recently gained increased attention due to their unique properties such as high specific surface area, higher charge transport capability and excellent chemical and mechanical properties. It is an ideal candidate for advanced functional devices such as solar cells, supercapacitors, gas sensors etc. Synthesis of TiO2 can be done cost-effectively by anodization of a Ti foil in a suitable electrolyte. The morphology, and hence the functional properties of the nanotubes strongly depend on the anodization parameters, therefore, this study aims to establish a relationship between anodization parameters and nanotube morphology. In this study, TiO2 nanotube array was successfully synthesized by anodizing a Ti foil in an electrolyte containing 99.5% Ethylene glycol, 0.5% DI water and 0.3% w/v NH4F. A range of anodization experiments were designed to vary the anodization voltage (20V-60V) and time (1h-3h) while keeping the other factors constant. Formation of crystalline nanotubes were confirmed by X-ray diffraction analysis, and scanning electron microscope was used to characterize the tube length and diameter. The diameters of synthesized nanotubes ranged from 28 nm to 90 nm while the tube lengths ranged from 2.5 μm to 15 μm. Statistical analysis of tube dimensions showed a strong relationship between process parameters and tube dimensions. Within a 3-hour period, voltage is found to be the most significant parameter on diameter and length of the growing tubes. It was found that the tube diameter obeys the relationship D = 1.109V + 6.863t + 0.284 where D is nanotube diameter, V is anodization voltage and t is anodization time. This study thus facilitates the researchers to tailor make the structure of the TiO2 nanotube layer according to the properties required.
item: Conference-Abstract
Mechanical behaviour of Cu-Zr binary metallic glasses: a molecular dynamic simulation study
(Department of Materials Science and Engineering, 2020-02) Gamage, NH; Madhushan, PAC; Sitinamaluwa, HS; Abeygunawardane, AAGA
Metallic glasses (amorphous alloys) have gained increased attention in recent times due to their unique combination of mechanical properties such as high tensile strength, fatigue and wear resistance together with higher toughness values. However, the underlying deformation physics of these materials remain less firmly established as compared with crystalline alloys. One reason is the difficulty of characterization of material structure, as these materials do not have long range order in their atomic arrangements. Material modelling and simulation methods have paved new ways for the advancement of material development, modification and processing. For the study of amorphous materials, atomistic modelling and simulation techniques have proven to be very useful, as these techniques allow a closer look of local atomic environments of these materials. In this research, molecular dynamics simulation is used to analyze mechanical behavior of Cu- Zr binary metallic glasses under tensile forces. Firstly, the relationship of toughness and strength over a range of atomic compositions of Cu-Zr metallic glasses (45 % Zr to 55 % Zr)is analyzed. In addition, the underlying deformation mechanisms of Cu-Zr metallic glasses were investigated. The MD simulations were done using Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) and OVITO software is used for visualization and analysis of the simulation results. As this study reveals, both fracture strength and toughness of Cu-Zr alloys are increased with increasing Zr content. Also, the Young's modulus of these alloys are also increased with the increasing Zr content. In-depth analysis of atomic structures suggests that the increasing free volume with increasing Zr content is responsible for high strength and toughness observed in the alloys with higher Zr content.
item: Conference-Abstract
Development of perovskite structured materials for solar cells
(Department of Materials Science and Engineering, 2020-02) Anuruddha, WAI; Arush, KM; Galhenage, AS; Abeygunawardane, AAGA
Perovskite solar cells have drawn significant attention from the scientists and the industrialists because of the high efficiency. However, the fabrication of high quality film of perovskite material is a very difficult task. In this study methyl ammonium lead iodide perovskite (CH3NH3PbI3) material was synthesized using two step spin coating method, first applying lead iodide (PbI2) and then methyl ammonium iodide (CH3NH3I, MAI). Fabricated films were analyzed by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). It is confirmed that the methyl ammonium lead iodide (CH3NH3PbI3) perovskite structured material with average crystal size of 550 nm was formed.The effect of morphological changes with the concentration of MAI was also studied. SEM images show the enhancement of the film quality with decreasing MAI concentrations. Maximum fill factor of 0.32 has been achieved with the lowest MAI concentration (0.1M).
item: Conference-Abstract
Synthesis and characterisation of two-roll mill processed natural rubber/graphene oxide modified silica nanocomposits
(Department of Materials Science and Engineering, 2020-02) Jayakody, JACA; Liyanage, NMVK; Abeygunawardane, AAGA
Tyre compounds consist of different additives such as antioxidants, fillers, plasticizing agents, vulcanising agents etc. in addition to natural rubber (NR). Two types of fillers; carbon black and silica, are used in rubber compounding. Carbon black is a powdered form of carbon which is completely miscible with organic rubbers. Nevertheless, silica (SiO2) is an inorganic compound which is not miscible with organic rubber. In addition, silica particles contain surface hydroxyl groups which tend to form hydrogen bonding leading to agglomerations. Coupling agents are used to address these issues when silica is used as a filler in rubber compounding. Different coupling agents, such as silane, alkanolamides, poly (diallyldimethylammonium chloride) (PDDA) etc. are widely used for this purpose. Performance of SiO2 and graphene, epoxidised NR and graphene and, NR and graphene oxide (GO), have been studied by previous researchers. This study was aimed to reduce aggregation of silica and to improve miscibility of silica in NR by modifying silica particles' surfaces with graphene oxide. GO was synthesized by following a modified Hummers' procedure. Silica surface modification was done by simply grinding silica and GO together at a ratio of 100:5. Characterisation of modified silica was performed via FTIR spectroscopy SEM analysis. GO modified silica filled rubber compounds were made on a two-roll mill as per a standard formula. Rheological properties of the compounds were studied by MDR rheography and the mechanical properties such as, tensile strength, tear strength etc. of the vulcanisates were measured following appropriate standards. Overall results indicate that the modification technique used in the study has enhanced the dispersion of silica in rubber imparting some improvements in mechanical properties of NR vulcanisates.
item: Conference-Abstract
Effect of marine environment on corrosion of mild steel
(Department of Materials Science and Engineering, 2020-06) Divanka, JHHT; Dilrukshi, RAS; Guluwita, SP; Abeygunawardane, AAGA
Corrosion is a major problem in steel structures used in marine environments. This project was carried out to investigate the effect of environmental factors in Sri Lankan coastal area for the uniform corrosion rate of mild steel. The results are used to derive an equation for the calculation of the corrosion rate. This project also serves as a part of a large-scale project to create a corrosion map for Sri Lanka. Mild steel samples were exposed to the marine environment for a four month period in Negombo, Moratuwa, Galle and Tangalle. The samples were collected in every two weeks for the analysis of corrosion rate. In addition, passive samples were placed on each place to investigate the Sulphur deposition and Salinity of those areas, and both parameters were measured monthly. Statistical analysis of the data was done to derive the following equation to obtain a relationship of corrosion rate with the environmental conditions such as level of Salinity, Sulphur deposition, cumulative rainfall and temperature. CR=0.245(T)+0.023(SO )+0.034(RF)+0.005(Cl- )-8.435 Where, CR = Corrosion Rate (mg.m-2day-1) T= Temperature (0C) RF= Rainfall (mm.day-1) SO = Sulphur deposition rate (mg.m-2day-1) 2 Cl- - 2 -1 = Chloride deposition rate (mg.m day ) This method has the advantage of assessing the corrosion rate of mild steel, before applications such as structural requirements.
item: Conference-Abstract
Effect of graphene layer thickness on performances of dye-sensitized solar cells
(Department of Materials Science and Engineering, 2020-02) Senaratna, HMA; Madushan, SAD; Galhenage, AS; Abeygunawardane, AAGA
Dye-sensitized solar cells (DSSCs) use platinum electrode as the counter electrode. In this study, to reduce the overall cost of DSSCs, graphene electrodes were fabricated as an alternative to platinum electrode. Graphene electrode was made using electrophoretic deposition method (EPD). The effect of reaction time on the graphene electrode formation was analyzed by keeping the reaction temperature at room temperature (250C) and voltage at a constant value (10 V). With increasing the reaction time increases grapheme layer thickness. DSSCs were also fabricated using the prepared grapheme electrode and the effect of film thickness on the cell performances were studied. The maximum efficiency of 0.61% has been achieved when the grapheme layer thickness is 1.15 μm.
item: Conference-Abstract
Retrospective determination of water-to-cement ratio (w/c) of concrete through ultrasonic pulse velocity measurements
(Department of Materials Science and Engineering, 2020-06) Anushan, R; Dilaittan, V; Sivahar, V; Piyathilake, SAKVM; Gamage, JCPH; Abeygunawardane, AAGA
The objective of this research is to find a method to determine the water-cement ratio that has been used in a concrete during construction, retrospectively. Water-Cement ratio affects the properties of concrete including its strength. Ultrasonic Pulse Velocity (UPV) of concrete can be related to its strength. These inter-relations can be used as the tool to achieve our objective. Different grades of concrete with varying water-cement ratios were used in this study. 28-day strength was measured using the standard concrete cubes and UPV measurements also were done for the same samples. 28-day strength of concrete can be considered as its long-term strength, as it does not change much after 28 days. UPV and 28-day strength of concrete, both found to decrease with the increase of water- cement ratio. These reductions were due to increased volume of capillary voids and micro- cracks within concrete transition zone and porous structure within the interconnected hydrates. The relationships established can be used to predict the water-cement ratios used in concrete structures retrospectively.
item: Conference-Abstract
Synthesis and characterization of natural rubber/ silica/graphene-based-materials nanocomposites (latex based)
(Department of Materials Science and Engineering, 2020-02) Madushanka, PHHP; Kumarawadu, PD; Liyanage, NMVK; Abeygunawardane, AAGA
Silica is used as a filler for reinforcement of Natural Rubber Latex (NRL) for non-black products. But silica is an inorganic compound and NRL is organic. Furthermore, silica has high filler to filler interactions so that silica doesn't disperse well in the NRL and agglomerations occur. Therefore, nowadays coupling agents like "silane" are used for dispersing silica uniformly in NRL without agglomeration. In this research Graphene Oxide (GO) is used as a graphene-based material to improve filler rubber interactions and to disperse silica in the NRL. GO was synthesized using improved Hummer's method as a pre-development method. There graphite was used as the main raw material. Then several samples of GO modified micro- silica (GOMS) and nano-silica were synthesized by sonication method. Compounded NRL films were then prepared according to a formula by varying the filler amount and vulcanized in an oven. GO, GOMS are characterized by Fourier Transform Infra-Red (FTIR) and X-ray Diffraction (XRD). Further GO, GOMS and GOMS added NRL vulcanized films were characterized by Scanning Electron Microscope (SEM). Mechanical properties of GOMS fillers added NRL vulcanized films were also tested. Some improvement in mechanical properties were observed in GOMS added NRL vulcanized films.
item: Conference-Abstract
Relationship between ultrasonic pulse velocity and compressive strength of concrete with different mix designs
(Department of Materials Science and Engineering, 2020-02) Saj, ARM; Prasanth, Y; Sivahar, V; Piyathilaka, SAKVM; Gamage, JCPH; Abeygunawardane, AAGA
It is a well-known fact that ultrasonic pulse velocity (UPV) is directly related to the quality of the concrete and therefore to its strength. However, these relationships are not independent of the type of concrete mix used. In addition, different standards use different mix designs for the same concrete grade. The objective of this study is to explore the possibility of obtaining a universal relationship between UPV and compressive strength of concrete that is independent of the mix design. Three standards of mix designs were chosen for this study, namely BS, ACI and IS. Standard samples made with the different mix designs were tested for compressive strength and UPV. The results obtained in this study revealed that, in order to obtain a universal correlation between the compressive strength and the UPV values among the different mix designs, a statistical approach would be required.
item: Conference-Abstract
Optimization of nano-crystalline cellulose formation from cellulose
(Department of Materials Science and Engineering, 2020-02) Weerakkody, KM; Wathsala, KPT; Samarasekara, AMPB; Amarasinghe, DAS; Abeygunawardane, AAGA
This research work is based on the process optimization of nanocellulose extraction from chemically purified cellulose. Cellulose was extracted from rice straws of BG 352 which contains the highest cellulose percentage among other rice species in Sri Lanka. This process included dewaxing, delignification, bleaching, acid hydrolysis, centrifugation, dialysis, sonication and freeze drying. X-ray diffractometer, FTIR, Laser particle size analyzer, SEM, EDX were used to examine & investigate the effect of each chemical treatment on the chemical structure of the extracted cellulose fibers. FTIR was used to compare the chemical structure of untreated and treated fibers. The chemical compositions of fibers including cellulose, hemicelluloses, lignin, and silica were determined by different techniques. The results showed that the cellulose content of the bleached fibers was increased by around 71% compared to the raw materials. XRD analysis concluded the decrement of crystallinity with an increment of the temperature and time of the centrifugation process. The optimum centrifugation conditions were found at 8000 rpm, 10 min 4 times at room temperature for the centrifugation speed and centrifugation time respectively. The optimum dialysis conditions were determined for regenerated cellulose membranes with 12-14 kDa molecular weight cut off (Fisher brand, Pittsburgh, PA) against distilled water for 4 days using a cellulose membrane in distilled water until a constant pH was achieved. The sonication process parameters were optimized as for 3 hours sonication time, 25W 20kHz and amplitude of 50% in an ice bath to avoid overheating, to disperse the nanocrystals for the sonication frequency and sonication time. Finally, the aqueous suspension was freeze-dried in liquid nitrogen to obtain Nano Crystalline Cellulose powder. The dimensions and morphology of the chemically and mechanically extracted nanofibers were investigated by Scanning Electron Microscopy and Laser Particle Size Analyzer. The results of the image analyzer showed that almost 50% of extracted materials are within the range of 64-98 nm and length of several micrometers.
item: Conference-Abstract
Investigation of thermal and mechanical properties of micro cellulose based composites
(Department of Materials Science and Engineering, 2020-02) Silva, JASR; Maduranga, SMK; Samarasekara, AMPB; Amarasinghe, DAS; Abeygunawardane, AAGA
This research is based on preparation of a composite with Micro Crystalline Cellulose (MCC) and Polypropylene (PP). MCC is hydrophilic and PP is hydrophobic in nature. To avoid less compatibility of these two materials, surface modification was done for MCC. Coconut oil was used as a green surface modifying agent in this research. Transesterification mechanism was used for surface modification. Modified MCC was characterized by using specific techniques to confirmation of surface modification. PP based composites were prepared by varying 1-5 wt%. percentages MCC for both unmodified and modified MCC conditions. Ingredients were blended in an internal mixer. Composites were prepared by pressing compounded mixers using compression molding technique. Mechanical properties and thermal properties of prepared composites were characterized under standards conditions. Tensile test, water absorption test and hardness test were conducted for all prepared composites. Vicat softening temperature (VST), differential thermal analysis and Thermo gravimetric analysis were conducted for all prepared composites according to standards. A mechanical property prediction model was formulated to model the tensile strength and tensile modulus of PP-MCC based composites. Modified Halpin-Tsai equation model was used to predict above mentioned properties. It was observed that the properties of modified MCC-PP composites were higher than the unmodified MCC-PP composites. Results which were obtained from predicted modified Halpin-Tsai model were in good agreement with experimental data. According to the outcomes of this research, biodegradable, eco- friendly and environment- friendly MCC can be used to improve mechanical and thermal properties of PP based composites. Readily available, cheap and environment-friendly coconut oil can be used for MCC surface modification. This developed composite can be used for various engineering applications.
item: Conference-Abstract
A study on reducing casting defects of sand casted water pumps
(Department of Materials Science and Engineering, 2020-02) Dawa, T; Lhamo, T; De Silva, GIP; Abeygunawardane, AAGA
Casting is one of the useful processes in producing products from utensils to machinery components. However, major disadvantage of this process is accompanying of casting defects, which bring great loss to the industry. Casting defects occur due to various reasons which are hard to control under the industrial environment. Many researchers have conducted experiments to find the best combination of process parameters which causes minimum casting defects. In such efforts, casting defects has been considerably reduced (up to 6%) by varying the moulding sand properties. Jinasena(Pvt) Ltd is one of the oldest pump manufacturers in Sri Lanka, however, currently they are suffering from high rate of sand-casting defects of 12% which leads to water leakage. This research focuses on analysis of these casting defects quantitatively and qualitatively, determining the causes, and suggesting effective solutions. It was found that shrinkage and blowholes were two critical defects leading to water leakage of water pump casing. Generally, it is well known that molding sand properties, metal pouring temperature, design of gating system and chemical composition of the raw material are vital factors that lead to the formation of casting defects. The influence of these major factors on formation of shrinkage and blowholes was studied in this work. The experimental results showed that improper design of gating system and deviation of the moulding sand properties dominantly affect the shrinkage and blowhole defects.
item: Conference-Abstract
A study of the effect of load on the depth of sulphide stress corrosion of steel used in petroleum pipelines
(Department of Materials Science and Engineering, 2020-02) Rathnayaka, RMMB; Madushan, HEMD; De Silva, GIP; Abeygunawardane, AAGA
The phenomenon of sulfide stress corrosion (SSC) can result in catastrophic failures in pressurized equipment and piping leading to extensive damages, injuries and possible fatalities. Sulfide stress corrosion, a major degradation process in metals, is commonly associated with the petroleum industry where a high concentration of H2S is involved. This research focuses on developing a relation between depth of SSC and applied load under a constant H2S concentration for a given time period. Furthermore, the mechanism of the propagation of sulfide stress corrosion is studied via microstructural analysis. According to the NACE standard solution "B" at the room temperature, the corrosion behavior of pipeline steel was evaluated. A special apparatus according to the NACE standards was fabricated for the testing process. The prepared samples of pipeline steel API 5L Grade B was tested under set of pre-determined loads while maintaining constant H2S concentration and pH value of 3.0 ± 0.5 for a constant time period. Thereafter, SEM microscopy and EDAX analysis were performed on the cross sections of corroded specimens. Relations of depth of corrosion versus applied load, and load at fracture versus applied load have been developed. Also, an interpretation is given for the propagation mechanism of SCC in terms of microstructural analysis. The ultimate objective of this work is to develop a model to predict the depth of corrosion occurred under different H2S concentrations, loads/pressure and exposure time periods.
item: Conference-Abstract
Fabrication of split Hopkinson pressure bar apparatus to study uniaxial high strain rate behavior of aluminium
(Department of Materials Science and Engineering, 2020-06) Rajapakshe, RMSW; Abeygunawardane, AAGA; ; Abeygunawardane, AAGA
There are many high strain rate related application in the world, including vehicle impact, blast welding, ballistic impact etc. Deformation mechanism of high strain rate applications differ from static applications, as a high strain rate application is solely due to stress wave propagation. These high strain rate data are required for safety and structural integrity assessment of structures subjected to dynamic loading. Engineering materials to be used in these applications should be selected irrespective of the deformation behavior witnessed in static uni-axial tensile test. Split Hopkinson Pressure Bar (SHPB) apparatus is used to study high strain rate behavior of different engineering materials (102 s-1 - 104 s-1) under uni-axial loading applications. In this work, compression type SHPB apparatus was fabricated in- house, is consisted of incident bar, transmission bar with properly mounted strain gauges to measure strain under dynamic conditions. The incident bar was impacted using standard single mass pendulum. Incident bar and Transmission bar was made of mild steel and Aluminium was selected as the test sample. Dynamic stress - strain behavior under different strain rates were determined using standard experimental approach associated to SHPB apparatus, followed by classical numerical approach pertinent on uni-axial stress wave propagation theory. The results obtained through SHPB apparatus and theoretical calculations were compared and analyzed. Dynamic Compressive Yield Stress for Aluminium was calculated for different strain rates, and the strain rate sensitivity was clearly witnessed. The results between experimental and theoretical values agreed considerably and spare deviation from the theoretical calculations was identified due to friction of the contact surfaces and wave dispersion effects.
item: Conference-Abstract
Development of a methodology to identify repairable photoreceptor drums
(Department of Materials Science and Engineering, 2020-02) Sampath, WGC; Senarath, GN; Attygalle, D; Abeygunawardane, AAGA
Toner cartridges are discarded due to the degradation of the organic photoconductor while the other parts of the cartridge are in usable condition. This research is focused on developing a method to identify repairable drums. Since the condition of the used drum is unknown, identifying the primary cause for the quality deterioration of xerographic prints is of great importance in repairing these drums.The print quality deterioration can happen due to deterioration of charge transport layer alone,degradation of charge generation layer alone, or occurance of both simultaneously.The damaged charge transport layer could lead to a higher residual potential due to trapped charges in the charge transport layer, and that finally affect the print quality. A locally fabricated setup was used to obtain dark decay curves and photoinduced discharge curves. These curves were then used to identify repairable drums successfully. Furthermore, the wear-out thickness of the charge transport layer was also estimated using the same data. This information was then used to develop a repair methodology for the damaged drums.
item: Conference-Abstract
Development of a piezoresistive pressure sensor using laser scribed graphene
(Department of Materials Science and Engineering, 2020-02) Prabhath, AAN; Perakotuwa, HPTS; Attygalle, D; Abeygunawardane, AAGA
Pressure sensors are often used in applications in the areas of direct pressure sensing in weather instrumentation, aircrafts, automobiles, machinery and Altitude sensing in aircraft, rockets, satellites. Development of piezo resistive commercial pressure sensors is currently restricted to Silicon, Polysilicon thin film, bonded metal foil and sputtered thin film. Properties of graphene shows the potential to develop more accurate and cheaper piezo resistive pressure sensors. This research is focused on the development of such a graphene based pressure sensor for commercial applications. Major steps towards the success of the research was to reduce graphene oxide to graphene from laser scribing method so that chemical reduction steps are omitted and then to design and fabricate a functional pressure sensor. In this research, graphene oxide was synthesized by modified hummers method. The prepared graphene oxide was characterized using FT-IR spectroscopy, XRD, TGA analysis and SEM. The sensors were fabricated using laser reduction of graphene oxide films that were coated on PET (polyethylene terephthalate) substrates. Sensor calibration was done and optimizing steps were taken for better functionality of the sensor. Uniform films of graphene oxide were prepared by drop casting method. Laser reduced graphene oxide has shown an electrical conductivity comparable to chemically reduced graphene oxide. Functionality of the sensor was analyzed after calibration and significant resistance change with applied pressure was observed. Response time of the sensor was coupled with the design of the apparatus used. Laser reduced graphene has shown the potential to design simple, low cost pressure/strain sensors.
item: Conference-Abstract
Development of a low-cost ceiling material based on local rice husks and waste plastics
(Department of Materials Science and Engineering, 2020-02) Lakmal, TCT; Chathurika, KPI; Udayakumara, SV; Abeygunawardane, AAGA
In the modern world, plastics play a dominant role among all other types of materials. However, not like other materials, plastics take long time to degrade in normal environmental conditions. Plastics used in packaging industry are often discarded to the environment and generates many environmental issues. Due to these issues, past few years many researches focused on recycling and reusing waste plastics. One of the main methods of recycling plastic is making composites. This study was focused to develop a composite material for ceiling sheets using virgin and waste low-density polyethylene and local rice husk. The rice husk- LDPE composite samples were made by using compression moulding techniques after mixing different proportions of rice husk with LDPE. Tensile strength, Flexural strength, swelling, water absorption, Impact strength, hardness and thermal conductivity were checked for all the samples. Results show increasing of hardness, swelling, water absorption and thermal conductivity and reduction of tensile strength, flexural strength, and impact strength with increasing percentage of rice husk. According to the test results, Sample with 20:80 rice husk to LDPE ratio shows better results to use as ceiling materials based on the test results.
item: Conference-Abstract
Phosphoric acid treated rice husk as a low cost biosorbent for cadmium removal from wastewater
(Department of Materials Science and Engineering, 2020-02) Ranaweera, PB; Madushanka, HM; Udayakumara, SV; Abeygunawardane, AAGA
Heavy metals, a contaminant present in polluted water pose a major threat to humans due to its ability to cause various health risks such as cancers, defective bone mineralization and chronic kidney disease. The most affected areas are developing nations: mainly Asia and South America. Since most of these countries do not have the ability to use expensive water filtration techniques like saltwater desalination or using graphene-based water purifiers, it's essential to come up with a water purifier/filter made of affordable materials. Adsorption behavior of Cadmium ions to phosphoric acid treated rice husk has been studied in this project. Rice husk samples obtained from a local rice mill was cleaned and heat treated initially. Chemical treatment for the rice husk was done by treating with phosphoric acid under uniform conditions. SEM images of the rice husk after treating with phosphoric acid showed significant increase in pores proving the higher efficiency of adsorption due to increased surface area. Artificially contaminated water samples were prepared by diluting a stock solution of Cd2+ ions. Contaminant concentrations in the ppm and ppb range was then filtered by the treated rice husk. Experimental results proved favorable adsorption of Cadmium into phosphoric acid treated rice husk. Ppm range Cd2+ samples had an average adsorption rate of ~30% and the data fitted well for Langmuir and Freundlich isotherms. The highest adsorption percentage was observed in the 100-ppb region with an adsorption rate of ~90%.

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