|报告题目:||Optical coherence tomography for investigating the dynamics of drying latex|
|报 告 人:||Dr. Daniel Ou-Yang|
Dr. Ou-Yang received BS and MS from Taiwan Fu-Jen Catholic University, and Ph.D. from UCLA, all in physics. He was a postdoctoral fellow at U. Penn. He joined Lehigh University in 1988 and is now a full professor of physics and director of the Emulsion Polymers Institute. During his sabbatical leaves, he also served as visiting professors in France, Hong Kong, Taiwan, S. Korea and China. His laboratory conducts research in the general areas of experimental soft matter and biophysics, with focus on developing new techniques to investigate the equilibrium and non-equilibrium phenomena of colloids and biological systems at sub-cellular levels.
Controlling the dying process during latex coating formation is important for industrial coatings. How coated films are formed during drying can dramatically affect the mechanical, optical, and chemical properties of the final products. Controlling how films are formed is difficult because the dynamics of drying process are complex, and the interior of the films is not easily observable during the drying process. A variety imaging tools are being developed to understand the film formation process at the microscopic level. But all are with varied successes and limitations. Optical coherence tomography (OCT), a well-developed 3D optical imaging technique for medical diagnostics of skin tissues and the glucose level in the microcapillary of the retina, has shown a tremendous potential for in situ investigation of industrial coating and film formation. This talk will introduce the basic principles of OCT as well as its instrumentation for studying thick and opaque coatings. A case study of using OCT to study the drying of coatings made of different latex particles will be demonstrated to show the temporal and spatial resolutions of this technique. Video images taken by OCT will be shown to reveal the detailed dynamics of particles distribution during the drying of latex droplets, a phenomenon commonly referred as the coffee-ring effect.