Ultrasonic Microscopy Analysis of Corrosion -- A Nondestructive Evaluation of Paint Weathering Effects and Synthesis and Characterization of Nanoscale Water-reducible Polymer Particles
"The quantitative, nondestructive, high resolution study of long term weathering, especially corrosion, has been a coatings industry goal for decades. The use of high resolution ultrasonic microscopy coupled with digital image analysis and low cost mass digital storage allowed the rate and detailed progress of corrosion, even that not visible to the eye, to be studied without sacrificing panels. Information unattainable in the past can be readily obtained for salt fog, Prohesion, exterior exposure, QUV or other weathering tests. The study presented here showed an alkyd and an epoxy coating, on both aluminum and steel, exposed to Prohesion or salt fog over hundreds of hours. The corrosion rate was evaluated and the ability of the technology to predict failure at an early time frame would be presented. Its potential to shorten the development cycle for many high performance coatings would be discussed. The use of water-borne coatings has been growing fast because of the concern of healthy environments. In our studies, nanoscale water reducible acrylic copolymers (PMMA-MAA) with zero volatile organic compound (VOC) were synthesized and characterized. Five controllable variables which were molecular weight, acid number, %solids of polymer dissolved in THF, extent of neutralization and flow rate of water reduction were applied in the design and analysis of experiments to investigate the most significant variables affecting the particle sizes. Particle size analysis was used to measure the polymer sizes in water solution which were in the range between 4-6nm; DSC and solid state 1H NMR proved that there were associated water on the surface of the polymer particles which enlarged the particle sizes and the content of this kind of water could be calculated. The coalescence time of the water reducible paints using the nanoscale water reducible PMMA-MAA would be measured by Taber abrasion test compared with the latex paints"--Abstract, page iii.
Nanoscale polymer synthesis, Water-reducible resin, Chemistry
Missouri University of Science and Technology
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