Levich Institute Seminar Announcement, 02/21/2017
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Ralph Colby
Penn State University
Department of Materials Science and Engineering
A brief interval of shear is applied to various semicrystalline polymer melts just above their melting temperature and at high enough shear rate this creates flow-induced precursors that accelerate isothermal crystallization on quenching. The precursors are found to be remarkably stable so that the sheared sample can be 1) studied in the DSC to observe crystallization on cooling at 5 K/min that is typically at a temperature 15 K higher than the crystallization of the same polymer that has not been sheared and 2) studied in an optical microscope hot stage to observe isothermal rates of nucleation and growth and final morphology. The precursors can also be annealed at various elevated temperatures to study their stability. We compare results on isotactic polypropylenes, poly(ethylene terephthalate)s, poly(ether ether ketone)s and Nylon 6,6 to learn which aspects of flow-induced crystallization are universal to all semicrystalline polymers and which are polymer-specific.
BRIEF ACADEMIC/EMPLOYMENT HISTORY
Ralph H. Colby received his B.S. in Materials Science and Engineering from Cornell University in 1979. After working for two years at the General Electric Company in rheology research and process development, he attended graduate school at Northwestern University, where he received his M.S. and Ph.D. in Chemical Engineering in 1983 and 1985. Graduate research focused on rheology of linear polybutadiene melts and solutions, and included 15 months as a visiting scholar in the Exxon Research and Engineering Company, Corporate Research - Science Laboratories. He then worked for ten years at the Eastman Kodak Company in their Corporate Research Laboratories. Rheology research areas over these ten years included linear polymer melts and solutions, miscible polymer blends, block copolymers, randomly branched polymers, polymer gels, liquid crystalline polymers, polyelectrolytes, proteins, surfactants and colloidal suspensions. In 1995, Dr. Colby was hired as an Associate Professor of Materials Science and Engineering at the Pennsylvania State University and was promoted to Professor in 2000.
RECENT RESEARCH INTERESTS
Rheology of all types of polymers