Onderzoeker in perspectief Willem Jan Soer: Het leuke aan promoveren is de diversiteit en de vrijheid

De keuze om te gaan promoveren was voor Willem Jan Soer heel eenvoudig. Want onderzoek doen beviel hem goed tijdens zijn studie Chemische Technologie in Enschede. Hij studeerde er eind 2002 af in de polymeerchemie. Nu ontwikkelt hij een organische coating voor magnesium

The development of a system of non-formal education : implications for the regional services councils in the Republic of South Africa

South Africa finds itself on the threshold of new challenges taking place in virtually every :possible sphere of life, i.e. the political, technological, human, social, economic and cultural spheres. The education system is also faced with these changes and cannot be viewed in isolation, rut demands new outlooks by educational planners and educationists. Non-formal education f orns an integral part of the provision of a system of education in' South Africa and is also influenced by these challenges. In order to make reasonable reconnnendations on how the challenges - particularly those of education management - should be approached by education planners and educationists, the following were investigated: * the role of and need for non-formal education in a system of education provision in south Africa so as to detenltlne the need to manage and administrate non-formal education successfully * the institutions which make the biggest contributions to the provision of non-formal education in south Africa, in order to point out where problem areas exist, and the resultant duplication, overlapping and fragmentation of training regional development and the role of regional bodies such as the Regional Development Advisory Conunittees, Regional Development Conunittees of the National Training Board, Training Board for Iocal Government Bodies and Regional services Councils the utilisation of Regional services COUncils to co-ordinate non-formal education at regional and local levels Based on the findings, an educational strategy is proposed to co-ordinate non-formal education on recJional and local levels through Regional Services councils.Educational Leadership and ManagementD. Ed. (Educational Management

Water Vapor Sorption and Diffusion in Secondary Dispersion Barrier Coatings: A Critical Comparison with Emulsion Polymers

The conventional method for synthesizing waterborne polymer colloids is emulsion polymerization using surfactants. An emerging method is the use of secondary dispersions (SD) of polymers in water, which avoids the addition of any surfactant. Although there are numerous studies of the water barrier properties (sorption, diffusion, and permeability) of waterborne emulsion (Em) polymer coatings, the properties of SD coatings, in comparison, have not been thoroughly investigated. Here, dynamic water vapor sorption analysis is used to compare the equilibrium sorption isotherms of the two forms of styrene–acrylate copolymers (Em and SD) with the same monomer composition. From an analysis of the kinetics of vapor sorption, the diffusion coefficient of water in the polymer coatings is determined. The combined effects of particle boundaries and surfactant addition were investigated through a comparison of the properties of SD and Em coatings to those of (1) solvent-cast polymer coatings (of the same monomer composition), (2) Em polymers that underwent dialysis to partially remove the water-soluble species, and (3) SD polymers with added surfactants. The results reveal that both the particle boundaries and the surfactants increase vapor sorption. The diffusion coefficients of water are comparable in magnitude in all of the polymer systems but are inversely related to water activity because of molecular clustering. Compared to all of the other waterborne polymer systems, the SD barrier coatings show the lowest equilibrium vapor sorption and permeability coefficients at high relative humidities as well as the lowest water diffusion coefficient at low humidities. These barrier properties make SD coatings an attractive alternative to conventional emulsion polymer coatings