Dr. Motoi Yamashita, associate Professor, Chiba Instutute of Technology, Japan

Biography: Dr. Motoi Yamashita received his PhD for crystal growth kinetics and morphology of polymers from Kyoto University in 2004. He worked as a research associate in Ritsumeikan University, Japan from 2005 to 2011 and a research scientist in TASC project in AIST, Japan from 2011 to 2012. From 2012, he is an associate Professor in Chiba Instutute of Technology. His research interests include crystal phase transition and conformational disorder at crystal growth interface of polymers.

Speech Title: Regime II-III transition in isotactic polybutene-1 tetragonal crystal growth: growth kinetics and morphology
Abstract: The lateral growth rate and growth shape morphology of isotactic polybutene-1 (iPB1) tetragonal crystals were investigated for crystallization from the melt over the temperature range 68–101 °C. The growth rate of tetragonal crystals is dependent on the degree of supercooling predicted by nucleation theory, and a regime II-III transition is observed at temperatures of 77–82 °C. The morphology of single crystals is rounded below temperatures of 77–80 °C, while the growth shape has a faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs between 77 and 80 °C. The regime II growth mode is observed above 82 °C and proceeds by multiple nucleation on the faceted growth front, while the regime III growth mode is observed below 77 °C and proceeds by rough surface growth on the kinetically roughened growth front. The observed regime II-III transition can therefore be explained by the morphology transition of crystal growth shape.