http://dr.lib.sjp.ac.lk/handle/123456789/7042 Thu, 23 Apr 2026 10:41:30 GMT 2026-04-23T10:41:30Z http://dr.lib.sjp.ac.lk/handle/123456789/7060 Manufacture of a Rubber Paver from a Blend of Nitrile Butadiene Rubber (NBRr) Latex Waste and Polyamide (PAr) Waste with Improved Properties Using Gamma Irradiation Abeykoon, W.B.D.; Liyanage, S.; Gunaratne, R. Attached; This study presents an experimental and practical analysis of the effect of gamma irradiation on blend of recycled nitrile butadiene rubber and polyamide samples for the manufacture of rubber paver as an alternative for cement paving blocks. Gamma irradiation radical-radical interaction crosslinking of elastomers and thermoplastic is a special crosslinking method as process is fast, pollution free and simple. NBR and PA polymer blends with various blend ratios were prepared through a low temperature mixing process. In this study a blend of polymer, based on waste nitrile butadiene rubber and waste polyamide (Nylon 6,6) has been investigate for several physical properties at varying NBR/PA content. NBR/PA (100:5) blend was selected for gamma irradiation. It achieved a tensile value of 3.040 N/mm2 , tear value of 23.805 N/mm2 and hardness value 40 (Shore A). These values are at higher range when compared with other ratio of (100:1.25), (100:2.5) and (100:10) NBR/PA blend. The structural properties of the polymer blends before and after they had been exposed to gamma irradiation were investigated. Rheological properties are measured to study curing behavior of blends. Mechanical properties like tensile strength, elongation at break, hardness and modulus at different elongations were studied and compared with those of un-irradiated sample. A relatively low-radiation dose (54.4 kGy) was found to be effective in improving the level of mechanical properties. According to FT-IR spectroscopic analysis of irradiated sample, there are no novel peaks corresponding to novel functional group in NBR/PA blend. Enhancement in mechanical properties has been observed for low radiation dose, showing that gamma irradiation affects the NBR/PA blend in a more efficient way at lower dose rates. Considering the current waste disposal difficulties and disposal cost (Rs.15,000 per ton) to the industry, a paving block sample was prepared as a green solution for waste NBR and Nylon 6,6. Water leachate of paving block was analyzed for heavy metals, BOD, COD, oil and grease levels. Those values are lower than the tolerance limits for discharge industrial waste into inland surface waters, on land for irrigation and into marine coastal areas. Mechanical properties of paving block such as compression set, hardness, swelling in water, UV exposure test, abrasion resistance, cut resistance, tear resistance and puncture resistance indicate suitability for application in hospital OPD floor area, nurseries, children play area, gymnasium and public walk ways. This study successfully offers solution for environmentally friendly disposal of nitrile rubber waste and nylon waste with reasonable profit to the industry. Sun, 01 Jan 2017 00:00:00 GMT http://dr.lib.sjp.ac.lk/handle/123456789/7060 2017-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/7058 Assessment of the applicability of Supercritical fluid extraction method in preparing Cinnamomum zeylanicum bark oleoresins extracts based on antioxidant assays Abira, S.; De Silva, K.R.D.; Thiruchenduran, S.; Gunaratne, R.D.; Paranagama, P.A. Attached; Cinnamon extracts have versatile industrial applications mainly focusing on its ability to act as an antioxidant. Cinnamon bark and oleoresins are the major raw materials for the industrial cinnamon extracts. Studies have shown that the antioxidant activity of the cinnamon extracts is subjective to their processing conditions. Putatively superior supercritical extraction (A) has been compared with Soxhlet’s extraction (B) using cinnamon oleoresin and the water extract (C) of cinnamon bark for their antioxidant activities. Extracts A, B, and C were assayed for their antioxidant activity through radical scavenging activity using DPPH assay. The linearity range for the analysis was 12.5g/ml - 800g/ml using butylated hydroxyl toluene (BHT) standard. All the extracts indicated significant antioxidant activity against blank at concentrations above 12.5g/ml. IC550 values of the samples were 587.68, 544.62 and 1261.40 respectively and 49.32 for BHT standard. The BHT equivalent radical scavenging activity of the extracts at IC50 were 0.084, 0.091 and 0.039 respectively. Supercritical fluid extraction exhibited significantly higher antioxidant activity when compared with water extract (p-value = 0.035). Extract from Soxhlet’s extraction didn’t indicate significant differences with the other two extracts at a significant level of 0.05 (p-values: A-B = 0.74; B-C = 0.057). This study indicates that extracts from cinnamon bark oleoresins extracted using the supercritical extraction method has higher antioxidant activity compared to water extracts but an equivalent antioxidant activity with extracts from Soxhlet’s extraction. Sun, 01 Jan 2017 00:00:00 GMT http://dr.lib.sjp.ac.lk/handle/123456789/7058 2017-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/7056 Synthesis and Characterization of hydroxyapatite from Eppawala Rock Phoshate for biomedical application as a value added product Hapuhinna, H.K.K.D.K.; Gunaratne, R.D.; Pitawala, H.M.J.C.; Wijesekara, K.B.; Ekanayake, E.M.D.K. Attached; Eppawala chloroapatite deposit is the only commercially available phosphate source in Sri Lanka, which is situated in Anuradhapura district. In this study, it was chemically changed into hydroxyapatite as a value-added product. It is a bioceramic which can be used for applications in orthopedics and dentistry due to its structural similarity with the mineral phase of mammalian bones and teeth. Sol-gel approach was used to synthesize products using diluted Nitric acid under different conditions. Synthesized Eppawala hydroxyapatite powder was characterized using X-ray Fluorescence (XRF), X-ray powder Diffraction (XRD), Fourier-transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM) in order to find out its composition, crystallinity, presence of functional groups, bonding type, surface morphology and microstructural features respectively. The FTIR spectroscopy results confirmed the formation of hydroxyapatite from apatite via the presence of hydroxyl groups. Those results coincided with the FTIR results of Human and Cow Bones. The XRD results reflected the formation of a hexagonal crystal structure of hydroxyapatite. Elementary composition and microstructural features of products were discussed based on the XRF and SEM results of the synthesized hydroxyapatite powder. The study concludes that there is a possibility of producing hydroxyapatite using commercially available Eppawala chloroapatite in Sri Lanka. Sun, 01 Jan 2017 00:00:00 GMT http://dr.lib.sjp.ac.lk/handle/123456789/7056 2017-01-01T00:00:00Z http://dr.lib.sjp.ac.lk/handle/123456789/7054 Survey of EEG-Based Biometric Authentication Jayarathne, Isuru; Cohen, Michael; Amarakeerthi, Senaka Attached; User authentication systems based on EEG (electroencephalography) is currently popular, marking an inflection point in the field. Recently, the scientific community has been making tremendous attempts towards perceiving uniqueness of brain signal patterns. Several types of methodical approaches have been proposed and prototyped to analyze EEG data with various signal-processing methods and pattern-recognition algorithms. Even though there are many stimulation methods to produce reasonable distinctiveness between subjects, optimization and lowering task complexity are still desirable from technoeconomic points of view. With recent technological advancement of EEG signal capturing devices, the process is getting comparatively simpler as devices are capable of providing better portability with reduced calibration time. However, most detailed analysis suggests that a minimal number of most appropriate channels should be selected for better results, even if a system is equipped with the most advanced hardware. Researchers are now focusing on implementing computationally low cost systems with better accuracy, regardless of complexity of the tasks. This paper is a review of several approaches, providing an overview of crucial design considerations in handling EEG data for extended accuracy and practical applicability to authentication Sun, 01 Jan 2017 00:00:00 GMT http://dr.lib.sjp.ac.lk/handle/123456789/7054 2017-01-01T00:00:00Z