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Paper and cellulosic materials hold a good promise of being candidates for flexible packaging materials provided suitable barrier properties such as water repellence and grease resistance are imparted to them. One of the methods to achieve these objectives is to surface modify paper/cellulose by applying thin fluorocarbon coatings on the surface. Fluorocarbon thin films produced by plasma enhanced chemical vapor deposition (PECVD) offer several advantages over the films produced by conventional polymerization means. Plasma deposited films are pinhole-free, chemically inert, insoluble, mechanically tough, thermally stable and highly coherent and adherent to variety of substrates. In this work, we investigate the use of PECVD technique to produce barrier films on paper and cellulosic materials. These films, with composition and properties not much different from PTFE, repel water and act as a good barrier to lipophilic materials. Two different monomers, pentafluoroethane (PFE; CF3CHF2) and octafluorocyclobutane (OFCB; C4F8), were investigated and compared in terms of deposition rates and final film properties. Various analytical techniques (XPS, FT-IR, SEM, Ellipsometry, Contact Angle Goniometry, etc.) were used to characterize the fluorocarbon films. The fluorocarbon coated paper exhibited hydrophobic character as evidenced by high water contact angles. Although the films allow water vapor diffusion, the films are hydrophobic and are not wetted when liquid water contacts these layers. Based on various thickness of these films deposited on surface of cellulose, there was a minimum PFE film thickness required to achieve a stable hydrophobic behavior. The fluorocarbon films investigated in this work also exhibited good resistance to lipophilic materials (e.g. oils, fatty acids, etc.). While techniques such as oleic acid penetration and TAPPI "oil-kit" test are commonly used in paper industry to qualitatively test the grease barrier properties of paper/cellulose, this work attempts to quantify the grease barrier properties of fluorocarbon coated paper using techniques such as magnetic resonance imaging (MRI) and quartz crystal microbalance (QCM). Finally, the feasibility of deposition of dual layer films by PECVD was investigated using PFE and n-isopropylacrylamide (NIPAAM) as precursors for applications in barrier packaging and printing.

Southern Africa generally has an arid climate and many hydrologists are predicting an increase in water scarcity over time. This research seeks to understand the implications of this in socio-political terms. The study is cross-disciplinary, examining how policy interventions can be used to solve the problem caused by the interaction between hydrology and demography. The conclusion is that water scarcity is not the actual problem, but is perceived as the problem by policy-makers. Instead, water scarcity is the manifestation of the problem, with root causes being a combination of climate change, population growth and misallocation of water within the economy due to a desire for national self-sufficiency in agriculture. The solution lies in the trade of products with a high water content, also known as 'virtual water'. Research on this specific issue is called for by the White Paper on Water Policy for South Africa. / Political Sciences / M.A. (International Politics)

Southern Africa generally has an arid climate and many hydrologists are predicting an increase in water scarcity over time. This research seeks to understand the implications of this in socio-political terms. The study is cross-disciplinary, examining how policy interventions can be used to solve the problem caused by the interaction between hydrology and demography. The conclusion is that water scarcity is not the actual problem, but is perceived as the problem by policy-makers. Instead, water scarcity is the manifestation of the problem, with root causes being a combination of climate change, population growth and misallocation of water within the economy due to a desire for national self-sufficiency in agriculture. The solution lies in the trade of products with a high water content, also known as 'virtual water'. Research on this specific issue is called for by the White Paper on Water Policy for South Africa. / Political Sciences / M.A. (International Politics)