Estudos sobre a aplicação de revestimentos contendo polímeros condutores e nanopartículas metálicas sobre superfícies de ligas de alumínio têm sido avaliados como alternativa para a proteção contra a corrosão de superfícies metálicas. Revestimentos composto por uma bicamada contendo nanopartículas metálicas (AgCe) e polianilina (PAni) ambos na presença do ácido dodecilbenzenosulfônico (DBSA) foram aplicados em ligas de alumínio do tipo AA6063 e AA7075 por deposição de um filme casting, com a finalidade de aumentar a adesão e a capacidade de dispersão de carga do filme sobre a superfície das ligas. A camada de nanopartículas metálicas de AgCe aparece como opção para melhorar a morfologia e textura do revestimento de cério, assim como, minimizar processos corrosivos e por conseguinte, proporcionar maior utilidade destes materiais. Estas propriedades são esperadas para aumentar a capacidade do filme de PAni para proteger as superfícies metálicas contra a corrosão. Neste trabalho as amostras foram caracterizadas por difratometria de raios-X, espectroscopia na região do infravermelho, espectroscopia na região do ultravioleta visível, espectroscopia de fotoelétrons excitados por raios-X, microscopia de força atômica, microscopia eletrônica de varredura, espectroscopia de energia dispersiva e microscopia óptica, também foram realizados voltametria cíclica e ensaios de corrosão, como potencial de circuito aberto, polarização potenciodinâmica e espectroscopia de impedância eletroquímica. Na análise dos testes de corrosão, os valores para o potencial do circuito aberto das ligas de AA6063 e AA7075 são mais positivos para as amostras revestidas, ou seja, mais nobre, em relação às amostras não revestidas. Para os ensaios eletroquímicos de 3h de imersão em NaCl 3,5% os valores do potencial de corrosão (Ecorr) obtidos na polarização potenciodinâmica foram de -0,63 V para AA6063/AgCe/PAni e -0,61 V para AA7075/AgCe/PAni. Para os ensaios de corrosão com maiores tempos de imersão de 6, 30 e 60h que foram realizados somente para os revestimentos de PAni e n-AgCe/PAni por apresentaram Ecorr mais positivos e por indicarem aderência relativamente boa, também indicaram um melhor desempenho contra corrosão para o revestimento contendo as nanopartículas metálicas mesmo após o tempo máximo de imersão em NaCl 3,5%. Assim, a eficiência de proteção calculada revelou valores de 80% para a liga AA6063 e 91% para a liga AA7075, confirmando que o revestimento de n-AgCe/PAni promoveu a proteção contra corrosão em até 60h de imersão em ambiente salino. / Studies on the application of conductive polymers and films containing metallic nanoparticles on surfaces of aluminum alloys have been evaluated as an alternative for corrosion protection of metal surfaces. Coatings consisting by a bilayer of AgCe nanoparticles and polyaniline (PAni) both in the presence of dodecylbenzenesulfonic acid (DBSA) were applied to aluminum alloy type AA6063 and AA7075 by deposition of a casting film, in order to increase the adhesion and the charge dispersion capacity of the film on the alloys surfaces. The AgCe metallic nanoparticles layer appears as an option to improve the morphology and texture of the cerium coating, as well as to minimize corrosive processes and therefore provide greater utility of these materials. These properties are expected to increase the ability PAni films to protect the metallic surfaces against corrosion. In this work, samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectrometry, atomic force microscopy, scanning electron microscopy, energy dispersive spectroscopy and optical microscopy and were also evaluated by corrosion tests as open circuit potential, potentiodynamic polarization, cyclic voltammetry and electrochemical impedance spectroscopy. In the analysis of corrosion tests, the values for the open circuit potential of AA6063 and AA7075 alloys were more positive for the coated samples, i.e. nobler relative to samples without coating. For the electrochemical tests of 3h of immersion in 3.5% NaCl, the values of corrosion potential (Ecorr) obtained in potentiodynamic polarization were -0.63 V for AA6063/AgCe/PAni and -0.61 V for AA7075/AgCe/PAni. For the corrosion tests with higher immersion times of 6, 30 and 60h, which were performed only for PAni and n-AgCe/PAni coatings because they presented more positive Ecorr and because of their relatively good adhesion, they also indicated a better performance against corrosion for the coating containing the metal nanoparticles even after the maximum immersion time in 3.5% NaCl. Thus, the calculated protection efficiency revealed values of 80% for the AA6063 alloy and 91% for the AA7075 alloy, confirming that the n-AgCe/PAni coating promoted corrosion protection in up to 60h immersion in the saline environment.

Das Ziel der vorliegenden Arbeit ist die bessere Verarbeitung von Polyanilin (PANI), da dies bisher ein großer Nachteil unter leitfähigen Polymeren war. Dazu wird ein sperriges Tensid und Dotand, Dodecylbenzensulfonsäure (DBSA) verwendet. Zur Synthese der PANI kommen zwei verschiedene Methoden zur Anwendung, die in dieser Dissertation in zwei Kapiteln beschrieben werden. Im ersten Teil wurden in einem kleinen Reaktionsvolumen (250 mL) PANI-DBSA-Suspensionen synthetisiert, wobei mit einem binären Gemisch aus 2-Propanol und Wasser als Lösungsmittel gearbeitet wird um die Löslichkeit zu unterstützen. Die micellenunterstützte Synthese produziert grüne Dispersionen, welche nach länger als einem Jahr noch keine sichtbare Ausscheidung zeigen. Eine detaillierte spectroelektrochemische Untersuchung der PANI-DBSA-Nanokolloide wurde durchgeführt und gibt eine bessere Erklärung der Charge-Transfer-Prozesse zwischen PANI-Kolloiden und Elektrodenoberfläche. In einem alkalischen Medium ist das UV-Vis-Spektrum von der Beweglichkeit der Anionen und von einem elektrokinetischen Phänomen abhängig. Um den „metal-to-insulator”-Übergang zwischen PANI-Kolloiden, welcher durch pH-Wert-Änderung des Mediums geschehen kann, zu zeigen, wurden UV-Vis- und pre-resonanz-Raman-Spektroskopie verwendet. Im zweiten Teil der Dissertation wird zur Polymerisation von Anilin sowie seinen Copolymeren mit o-Toluidin eine neue Technik der Polymerisation beschrieben, welche durch inverse Emulsion erfolgt. Diese benutzt Benzoylperoxid, ein ungewöhnlicheres organisches Oxidationsmittel. Die erhaltenen PANI sind in gebräuchlichen organischen Lösungsmitteln, wie in Chloroform, vollständig löslich. Mit einer klar-transparenten, grünen Lösung von PANI können metallische Oberflächen oder Glas leicht tropfenbeschichtet werden. Zyklische Voltammetrie und spektroelektrochemische Verfahren kamen zum Einsatz, um die Elektroaktivität, das UV-Vis-Verhalten und die „metal-to-insulator”-Übergänge der chemisch synthetisierten PANI als Funktion des verwendeten Elektrodenpotentials zu untersuchen. Die elektrische Leitfähigkeit der Materialien ist relativ hoch (R = 10 ). SEM-Untersuchungen zeigen, dass die Menge des zugesetzten DBSA die Morphologie des Polymers stark beeinflusst. Aus in situ UV-Vis-spektroskopischen Messungen lässt sich eine gute elektrochromische Reversibilität des Polymers erkennen. DBSA kann Poly(o-toluidin) (POT) effektiv dotieren, auch wenn von der Methylgruppe eine sterische Hinderung ausgeht. Die spektroskopischen Untersuchungen, wie UV-Vis, FT-IR, Raman-Spektroskopie und zyklische Voltammetrie, zeigen deutlich, dass wirkliche Copolymere gebildet werden und die Möglichkeit von Kompositen nicht in Betracht kommt. Das entstandene Poly(anilin-co-o-toluidin) (PAT) ist in schwach polaren Lösungsmitteln wie Chloroform löslich. Wie erwartet, sind die elektrischen Leitfähigkeiten der Copolymere viel kleiner als die Leitfähigkeit von PANI-DBSA.

Magister Economicae - MEcon / This study is an evaluation of development strategies that have been followed in South Africa. Lebowa is used as a case study for an assessment of the present strategy. The basic question is whether or not it is economically, politically and socially effective to follow the "homeland" development strategy. This approach places "homeland" states within confined political borders. Development policies are also confined to these borders. An alternative is to follow a broader regional development strategy, that spans across both political and economic borders. This may provide a more feasible approach to development. The present regional pattern of development, which focuses mainly on industrial decentralization, is discussed. The evaluation of the present strategy explores various other alternatives which may provide for a more effective regional development policy. In this context an assessment of 'backward regions/homelands' is provided. The central problem addressed is the country or 'homeland' versus regional orientation. To understand the problem, the core-periphery view on South Africa's regional growth pattern, is utilized. The PWV, Durban/ Pinetown and the Cape metropole areas may be taken as "core", where most of the economic activity takes place. One can also distinguish between the "inner-periphery", which is close to the core, and the "outer-periphery", further away from the core and which includes the Black Homelands. This core-periphery approach provides an understanding of the polarisation effect, which results in the "homelands" becoming poorer, whilst the urban areas grow richer. The main criticism of the of the modernisation or diffusionist approach is that the "trickle-down" or spread-effect from the core to the other regions does not really take place. Thus, regional aspirations are not satisfied. The South African Government's attempts to counter some of the forces of concentration have been questionable. Within the context of the diffusionist paradigm, trickle-down effects have not occurred because of the super-imposition of a political ideology onto this approach. Rather these areas are the result of polarization (re-inforced by political consideration) brought about by the concept of separate development. It is clear that South Africa's approach to regional development is in a process of change. This is mainly due to the failure of the "homelands" strategy. Since the mid 1970's it has become increasingly clear that the "homelands" could not really become economically independent (and internationally recognised), and development strategy concentrating on each that the uneconomic and inefficient."homeland" would be uneconomists critical of this unified economy. planners and politicians. approach have suggested that the whole South African economy should be planned as one economy, even if the homelands still maintain political independence. The nine development region mapping of South Africa, Regions A - J, came about as a result of attempting to address South Africa as a more unified economy. Up to now, the proposed role of the regions have not been clearly stated

Das Ziel der vorliegenden Arbeit ist die bessere Verarbeitung von Polyanilin (PANI), da dies bisher ein großer Nachteil unter leitfähigen Polymeren war. Dazu wird ein sperriges Tensid und Dotand, Dodecylbenzensulfonsäure (DBSA) verwendet. Zur Synthese der PANI kommen zwei verschiedene Methoden zur Anwendung, die in dieser Dissertation in zwei Kapiteln beschrieben werden. Im ersten Teil wurden in einem kleinen Reaktionsvolumen (250 mL) PANI-DBSA-Suspensionen synthetisiert, wobei mit einem binären Gemisch aus 2-Propanol und Wasser als Lösungsmittel gearbeitet wird um die Löslichkeit zu unterstützen. Die micellenunterstützte Synthese produziert grüne Dispersionen, welche nach länger als einem Jahr noch keine sichtbare Ausscheidung zeigen. Eine detaillierte spectroelektrochemische Untersuchung der PANI-DBSA-Nanokolloide wurde durchgeführt und gibt eine bessere Erklärung der Charge-Transfer-Prozesse zwischen PANI-Kolloiden und Elektrodenoberfläche. In einem alkalischen Medium ist das UV-Vis-Spektrum von der Beweglichkeit der Anionen und von einem elektrokinetischen Phänomen abhängig. Um den „metal-to-insulator”-Übergang zwischen PANI-Kolloiden, welcher durch pH-Wert-Änderung des Mediums geschehen kann, zu zeigen, wurden UV-Vis- und pre-resonanz-Raman-Spektroskopie verwendet. Im zweiten Teil der Dissertation wird zur Polymerisation von Anilin sowie seinen Copolymeren mit o-Toluidin eine neue Technik der Polymerisation beschrieben, welche durch inverse Emulsion erfolgt. Diese benutzt Benzoylperoxid, ein ungewöhnlicheres organisches Oxidationsmittel. Die erhaltenen PANI sind in gebräuchlichen organischen Lösungsmitteln, wie in Chloroform, vollständig löslich. Mit einer klar-transparenten, grünen Lösung von PANI können metallische Oberflächen oder Glas leicht tropfenbeschichtet werden. Zyklische Voltammetrie und spektroelektrochemische Verfahren kamen zum Einsatz, um die Elektroaktivität, das UV-Vis-Verhalten und die „metal-to-insulator”-Übergänge der chemisch synthetisierten PANI als Funktion des verwendeten Elektrodenpotentials zu untersuchen. Die elektrische Leitfähigkeit der Materialien ist relativ hoch (R = 10 ). SEM-Untersuchungen zeigen, dass die Menge des zugesetzten DBSA die Morphologie des Polymers stark beeinflusst. Aus in situ UV-Vis-spektroskopischen Messungen lässt sich eine gute elektrochromische Reversibilität des Polymers erkennen. DBSA kann Poly(o-toluidin) (POT) effektiv dotieren, auch wenn von der Methylgruppe eine sterische Hinderung ausgeht. Die spektroskopischen Untersuchungen, wie UV-Vis, FT-IR, Raman-Spektroskopie und zyklische Voltammetrie, zeigen deutlich, dass wirkliche Copolymere gebildet werden und die Möglichkeit von Kompositen nicht in Betracht kommt. Das entstandene Poly(anilin-co-o-toluidin) (PAT) ist in schwach polaren Lösungsmitteln wie Chloroform löslich. Wie erwartet, sind die elektrischen Leitfähigkeiten der Copolymere viel kleiner als die Leitfähigkeit von PANI-DBSA.

Thesis ((MPhil (Sustainable Development, Planning and Management))--University of Stellenbosch, 2010. / ENGLISH ABTRACT: Through the development of sustainable communities, a transformation process can be incited towards a more sustainable way of life. An important prerequisite of this transformation process is behavioural change. This thesis is based on the supposition that participation can contribute to behavioural change. Behaviour which supports the functioning of sustainable systems, is essential in the long term success of sustainable communities. To sustain this behaviour and create a sense of ownership, participatory processes need to encompass the initial phases of development (planning) as well as the implementation and management phase (governance). To secure the participatory involvement in the implementation phase anchor points need to be created in the planning phase, which enable participation of community members in the implementation phase. By means of a case study this thesis has analysed the role of participation in the pilot project in Grabouw, a medium-sized town in the Western Cape, South Africa. The key objective was to establish whether and in what manner, the participatory planning process anticipated the involvement of community members in the implementation phase. Research shows that in some occasions, participation is defined as an instrument to effectively manage contingencies and facilitate the implementation of government decisions. However, the case studies of Grabouw and Porto Alegre, illustrate that community participation can also be organised in such a way that it enables community members to be involved in a meaningful way in decision-making processes, enabling them to shape their own environment. Defined this way active participation is not merely an instrument but an integral part of a complex system encompassing opportunities for social learning. Active participation can incite a process of „conscientization‟ and empowerment, stimulating people to become aware of sustainable challenges and adapt their behaviour accordingly. This viewpoint on participation is in line with the multi-dimensional nature of sustainable development and based on the need to facilitate a continuous evolving learning system. Furthermore it supports the notion that sustainable development is not a fixed objective but a moving target. Within this perspective sustainable communities need to be flexible entities able to evolve in accordance with increased understanding of the complex interrelated issues of sustainable development. / AFRIKAANSE OPSOMMING: ‟n Transformasieproses, gerig op ‟n meer volhoubare lewenswyse, kan deur die ontwikkeling van volhoubare gemeenskappe aangemoedig word. ‟n Belangrike voorvereiste vir so ‟n transformasieproses is gedragsverandering. Gedragsverandering is nie ‟n individuele oefening nie, maar is stewig veranker in sosiale prosesse en word daardeur beïnvloed. Om gedragsverandering op groter skaal te stimuleer, is dit nodig dat individue as katalisators van gedragsverandering optree. Deelname speel ‟n vername rol om volhoubare gemeenskappe as platforms vir volhoubare gedragsverandering op te stel. Die bestaande verskeidenheid tussen die verskillende vlakke van deelname bemoeilik die opstel van een duidelik omlynde definisie van deelname. Die regering en ander gemeenskapsrolspelers het die waarde van deelname besef en dit het algemene gebruik geword om lede van die gemeenskap by die beplanning en/of beheer van volhoubare stedelike ontwikkeling te betrek. Kompleksiteit-teorie bied ‟n waardevolle perspektief in die strewe na dieper verstandhouding rondom die geleenthede en beperkinge van deelname. Hierdie verhandeling het deur middel van ‟n gevallestudie die rol van deelname in die loodsprojek op Grabouw, ‟n medium-grootte dorp in Wes-Kaapland, geanaliseer. Die navorsing wat vir dié verhandeling gedoen is, het deel uitgemaak van ‟n evaluasiestudie wat deur die Ontwikkelingsbank van Suider Afrika bekend gestel is en deur die Omgewingsevaluasie-eenheid aan die Universiteit van Kaapstad (UK) uitgevoer is. Die navorsing het getoon dat in sommige gevalle deelname gedefinieer word as ‟n instrument om omstandighede doeltreffend te beheer en die toepassing van regeringsbesluite af te glad. Die gevallestudies van Grabouw en Porto Allegre wys egter daarop dat deelname ook op so ‟n manier georganiseer kan word dat dit lede van die gemeenskap in staat stel om op betekenisvolle wyse by besluitnemingsprosesse betrokke te raak en sodoende hulle eie omgewing rangskik. Aktiewe deelname wat so gedefinieer word, is nie ‟n instrument nie, maar ‟n integrale deel van ‟n komplekse stelsel wat geleenthede vir sosiale leer omsluit. Aktiewe deelname kan ‟n proses van „gewetensprikkeling‟ en bemagtiging aanmoedig, wat mense stimuleer om bewus te word van volhoubare uitdagings en hulle gedrag dienooreenkomstig aan te pas. Hierdie siening oor deelname is in lyn met die multi-dimensionele aard van volhoubare ontwikkeling en gebaseer op die behoefte om ‟n voortdurende ontwikkelende leerstelsel te fasiliteer. Voorts ondersteun dit die denkwyse dat volhoubare ontwikkeling nie ‟n vasgeankerde doelwit is nie, maar wel ‟n bewegende teiken. Binne hierdie perspektief behoort volhoubare gemeenskappe buigsame entiteite te wees wat daar toe in staat is om met toenemende insig van die komplekse verbandhoudende aangeleenthede rondom volhoubare ontwikkeling, te groei.

Corrosion protection performance of a completely soluble polyaniline-dodecylbenzenesulfonic acid salt (PANI-DBSA) on C45 steel has been studied with electrochemical impedance and potentiodynamic measurements. Chloroform is the most suitable solvent to process the pristine PANI-DBSA because of negligible interaction of the solvent with the polyaniline (PANI) backbone. An anodic shift in the corrosion potential (<img src="http://scitation.aip.org/stockgif3/Dgr.gif" alt="Delta" align="bottom" border="0"><i>E</i>=~70&nbsp;&nbsp;mV), a decrease in the corrosion current and a significant increase in the charge transfer resistance indicate a significant anti-corrosion performance of the soluble PANI deposited on the protected steel surface. Corrosion protection follows the mechanism of formation of a passive oxide layer on the surface of C45 steel. In situ UV-Vis spectroscopy was used to investigate the differences in permeability of aqueous anions into PANI-DBSA. Preliminary results of electron diffraction studies show that PANI-DBSA possesses an orthorhombic type of crystal structure. An increase in the feed ratio of DBSA to aniline increases the tendency of aggregation of spherical particles of PANI obvious in transmission electron microscopy. PANI-DBSA slowly loses its electrochemical activity in acid free electrolyte without undergoing degradation.

Philosophiae Doctor - PhD (Chemistry) / Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are considered one of the most important subjects concerning electricity or energy storage which has proven to be problematic for South Africa. In this work, graphene oxide (GO) was supported with platinum, silver and copper nanoparticles anchored with dodecylbenzenesulphonic acid (DBSA) doped polyaniline (PANI) to form nanocomposites. Their properties were investigated with different characterization techniques. The high resolution transmission electron microscopy (HRTEM) revealed GO's nanosheets to be light, flat, transparent and appeared to be larger than 1.5 ?m in thickness. This was also confirmed by high resolution scanning electron microscopy (HRSEM) with smooth surfaces and wrinkled edges observed with the energy dispersive X-ray analysis (EDX) confirming the presence of the functional groups such as carbon and oxygen. The HRTEM analysis of decorated GO with platinum, silver and copper nanoparticles (NPs) revealed small and uniformly dispersed NPs on the surface of GO with mean particle sizes of 2.3 ± 0.2 nm, 2.6 ± 0.3 nm and 3.5 ± 0.5 nm respectively and the surface of GO showed increasing roughness as observed in HRSEM micrographs. The X-ray fluorescence microscopy (XRF) and EDX confirmed the presence of the nanoparticles on the surface of GO as platinum, silver and copper which appeared in abundance in each spectra. Anchoring the GO with DBSA doped PANI revealed that single GO sheets were embedded into the polymer latex, which caused the DBSA-PANI particles to become adsorbed on their surfaces. This process then appeared as dark regions in the HRTEM images. Morphological studies by HRSEM also supported that single GO sheets were embedded into the polymer latex as composite formation appeared aggregated and as bounded particles with smooth and toothed edges.

Corrosion protection performance of a completely soluble polyaniline-dodecylbenzenesulfonic acid salt (PANI-DBSA) on C45 steel has been studied with electrochemical impedance and potentiodynamic measurements. Chloroform is the most suitable solvent to process the pristine PANI-DBSA because of negligible interaction of the solvent with the polyaniline (PANI) backbone. An anodic shift in the corrosion potential (<img src="http://scitation.aip.org/stockgif3/Dgr.gif" alt="Delta" align="bottom" border="0"><i>E</i>=~70&nbsp;&nbsp;mV), a decrease in the corrosion current and a significant increase in the charge transfer resistance indicate a significant anti-corrosion performance of the soluble PANI deposited on the protected steel surface. Corrosion protection follows the mechanism of formation of a passive oxide layer on the surface of C45 steel. In situ UV-Vis spectroscopy was used to investigate the differences in permeability of aqueous anions into PANI-DBSA. Preliminary results of electron diffraction studies show that PANI-DBSA possesses an orthorhombic type of crystal structure. An increase in the feed ratio of DBSA to aniline increases the tendency of aggregation of spherical particles of PANI obvious in transmission electron microscopy. PANI-DBSA slowly loses its electrochemical activity in acid free electrolyte without undergoing degradation.