Measurement studies on superhydrophobic materials C3 - Advanced Materials Research
- Authors: Devasahayam, Sheila , Yarlagadda, Prasad
- Date: 2014
- Type: Text , Conference paper
- Relation: 2nd International Conference on Material, Mechanical and Manufacturing Engineering, IC3ME 2014 Vol. 988, p. 134-142
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- Description: Superhydrophobicity is directly related to the wettability of the surfaces. Cassie-Baxter state relating to geometrical configuration of solid surfaces is vital to achieving the Superhydrophobicity and to achieve Cassie-Baxter state the following two criteria need to be met: 1) Contact line forces overcome body forces of unsupported droplet weight and 2) The microstructures are tall enough to prevent the liquid that bridges microstructures from touching the base of the microstructures [1] In this paper we discuss different measurements used to characterise/determine the superhydrophobic surfaces.
- Description: E1
Evolution of novel size-dependent properties i polmre-matrix composites due to polymer filler interactions
- Authors: Devasahayam, Sheila , Bandyopadhyay, Sri
- Date: 2013
- Type: Text , Book chapter
- Relation: New developments in polymer composities research p. 1-20
- Full Text: false
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Abrasion characteristics of ores
- Authors: Devasahayam, Sheila
- Date: 2013
- Type: Text , Journal article
- Relation: Mineral processing and extractive metallurgy review : An International journal Vol. 34, no. 2 (2013), p. 114-129
- Full Text: false
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Application of particle size distribution analysis in evaluating the weathering in coal mine rejects and tailings
- Authors: Devasahayam, Sheila
- Date: 2007
- Type: Text , Journal article
- Relation: Fuel Processing Technology Vol. 88, no. 3 (2007), p. 295-301
- Full Text: false
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- Description: Particle size distribution (PSD) analysis of the Gregory mine coal rejects, over a period of time is presented. The PSD has important implications on several processes contributing to the acid mine drainage. In this paper, correlation between the particle breakdown in the coal rejects and the rate of oxidation of sulphides is presented. Difference between the initial and the subsequent values of particle size distribution coefficient over a period of time indicated a change in particle breakdown mechanisms. An initial physical breakdown due to structural breakdown/rearrangement caused by wetting of the sample, and subsequent breakdown caused by the combined effects of physical and chemical weathering are proposed. Total number of particles increased with time, as the mean size of the distribution decreased. Increase in surface area calculated form the PSD analysis followed a power law with respect to time. The pyrite oxidation rate is dominated by diffusion and mass transfer processes initially, and as the total surface area is increased, contributed by breakdown of larger particles, a phase boundary control dominates the oxidation process.
Predicting the Liberation of Sulfide Minerals Using the Breakage Distribution Function
- Authors: Devasahayam, Sheila
- Date: 2015
- Type: Text , Journal article
- Relation: Mineral Processing and Extractive Metallurgy Review Vol. 36, no. 2 (2015), p. 136-144
- Full Text: false
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- Description: The study validates how the original grain size of the ore influences the propensity of a mineral to be liberated. An Australian zinc ore was investigated for the variation in composition with respect to grain size using QEMSCAN. The breakage patterns of the ore showed that the liberated phases were influenced by the association of various phases in the original ore affecting the size distribution of different species. The combined breakage and the QEMSCAN data were used to predict the effect of grinding which affects the grain size and hence the distribution of grain phases in different size fractions, and relates the latter to the proportions of binary and ternary composite grains in the original ore sample. The study provides a direct correlation between the grain size distribution resulting from grinding to the liberated free minerals, binary and ternary composites. The liberation model parameters determined in the present study are used to predict the liberation of different mineral compositions directly from the size distribution analysis as well as from the t(10) parameter. The study has implications for optimizing grinding practice for improved beneficiation, and liberation as over-grinding produces undesirable fines difficult to process as well as incur additional energy input.
FT-Raman studies of a range of polyimides subjected to high-energy Radiations at room and elevated temperatures
- Authors: Devasahayam, Sheila , Hill, David , Connell, John
- Date: 2006
- Type: Text , Journal article
- Relation: Journal of Applied Polymer Science Vol. 101, no. 3 (2006), p. 1575-1582
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- Description: A range of polyimides have been subjected to electron beam radiolysis at different temperatures. These polyimides were chemically designed to suit space applications, being either transparent or having groups which provide oxidation resistance. The structural changes that occur in the polyimides, when subjected to electron beam irradiation doses up to 18.5 MGy and up to temperatures close to their glass transition temperatures, were studied using FT-Raman spectroscopy. The range of polyimides studied included a series of perfluoropolyimides, a silicon-modified polyimide, and Ultem. The changes in the Raman peak intensities of the different groups indicated scission reactions involving the imide rings and ether linkages. (c) 2006 Wiley Periodicals, Inc.
Brown coal dewatering using poly (Acrylamide-co-potassium acrylic) based super absorbent polymers
- Authors: Devasahayam, Sheila , Ameen, Anas , Verheyen, Vincent , Bandyopadhyay, Sri
- Date: 2015
- Type: Text , Journal article
- Relation: Minerals Vol. 5, no. 4 (2015), p. 623-636
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- Description: With the rising cost of energy and fuel oils, clean coal technologies will continue to play an important role during the transition to a clean energy future. Victorian brown coals have high oxygen and moisture contents and hence low calorific value. This paper presents an alternative non evaporative drying technology for high moisture brown coals based on osmotic dewatering. This involves contacting and mixing brown coal with anionic super absorbent polymers (SAP) which are highly crossed linked synthetic co-polymers based on a cross-linked copolymer of acryl amide and potassium acrylate. The paper focuses on evaluating the water absorption potential of SAP in contact with 61% moisture Loy Yang brown coal, under varying SAP dosages for different contact times and conditions. The amount of water present in Loy Yang coal was reduced by approximately 57% during four hours of SAP contact. The extent of SAP brown coal drying is directly proportional to the SAP/coal weight ratio. It is observed that moisture content of fine brown coal can readily be reduced from about 59% to 38% in four hours at a 20% SAP/coal ratio. © 2015 by the authors; licensee MDPI, Basel, Switzerland.
Study of Victorian Brown Coal Dewatering by Super Absorbent Polymers using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy
- Authors: Devasahayam, Sheila , Bandyopadhyay, Sri , Hill, David
- Date: 2016
- Type: Text , Journal article
- Relation: Mineral Processing and Extractive Metallurgy Review Vol. 37, no. 4 (2016), p. 220-226
- Full Text: false
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- Description: A simple and useful method to monitor the water content of coal samples using Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is presented. ATR-FTIR analyses of oven-dried and polymer-dried brown coal samples are discussed. The difference spectra indicate that the drying of as-received coal at room temperature using a Super Absorbent Polymer (SAP) removes only 44% of moisture compared to oven drying at 105 °C. As the SAP does not completely remove the water from the coal the possibility of explosion due to oxidation of the coal powder is greatly reduced. SAP drying is energy and emission efficient compared to oven drying method. At the pH < 5 studied SAP dewatering is dominated by physical processes. The movements in H-bonding observed in ATR-FTIR suggest a physico-chemical process. © 2016 Taylor & Francis.
Use of Secondary Ion Mass Spectrometry (SIMS) to identify fly ash mineral spatial and particulate distribution in epoxy polymer
- Authors: Ibraheem, Shahad , Devasahayam, Sheila , Standard, Owen , Bandyopadhyay, Sri
- Date: 2015
- Type: Text , Journal article
- Relation: International Journal of Mineral Processing Vol. 142, no. (2015), p. 139-146
- Full Text: false
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- Description: Fly ash from coal power stations consists typically of a series of oxide minerals. These minerals can have beneficial effects when used as reinforcement in a plastic matrix. In this work the advanced technique SIMS has been utilised to identify the spatial distribution of the various minerals in fly ash in an epoxy matrix with fly ash weights of 10% and 50%. It is observed that SIMS, which can scan normally to a precision of 0.5 to 0.05 wt.%, could positively identify the distribution of the fly ash mineral elements in the epoxy. Attempts were also made to identify the fly ash element distribution in the epoxy using a composition analysis method, namely, EDS. However, it is observed that in the present fly ash-epoxy composites, EDS could not identify the fly ash elements demonstrating SIMS is a much preferred identification technique than the popular EDS method. © 2015 Elsevier B.V. All rights reserved.
Alternative energy sources for the mineral sector : An overview
- Authors: Devasahayam, Sheila , Singh, Raman
- Date: 2016
- Type: Text , Book chapter
- Relation: Sustainability in the mineral and energy sectors Chapter 21 p. 377-401
- Full Text: false
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- Description: The cost of energy is projected to rise due to factors including infrastructure costs to transmit and distribute energy, commodity prices, exchange rates and geopolitical factors. Energy efficiency is one of the most cost-effective strategies for managing rising energy costs and growing concerns over greenhouse gas emissions. The mining industry has traditionally relied on conventional fossil- based fuel sources such as diesel, oil, coal and natural gas. This industry has a great opportunity to explore renewable sources, in order to meet its growing energy demands. Mining companies, espe- cially those at remote locations, need to understand the nature and availability of local renewable energy – from geothermal and hydroelectric to solar and wind and biomass. The alternative energy sources often translate to reducing CO 2 emissions. In this chapter, alternative energy sources such as solar energy, microwave energy, geothermal energy, nuclear energy, blue energy, bioenergy and waste energy recovery and their application in the mineral sector are discussed.