Abstract
Following the introduction of legislation restricting the manufacture and use of coatings containing volatile organic solvents, alternative waterborne coatings are increasingly being adopted for adhesive, protective, and decorative applications. Better understanding is therefore sought of the behaviour of waterborne coatings during drying and film formation, and of their physical characteristics after film formation is complete. This thesis describes one-dimensional Magnetic Resonance Imaging studies of the distribution of water and solid particles through the depth of aqueous latex layers during drying which investigate how particle distribution and concentration are influenced by the competing forces of diffusion and evaporation. The manner in which the balance of these forces affects the formation of a crust or dry layer at the latex-air interface is also investigated. In the case of acrylic latexes, the same technique has been used to show that, when re-wet by the application of further latex during drying, drying layers absorb a quantity of water proportional to the water volume fraction at the time of re-wetting. A study is also reported in which Nuclear Magnetic Resonance diffusometry and, for the first time, two-dimensional Nuclear Magnetic Resonance relaxation and diffusion correlation and exchange measurements are used to investigate waterborne coatings. These methods allow both the pore size and the total pore volume of some emulsion paint products to be estimated.