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AFM image of etched UHMWPE shish-kebab scaffold. Polymer (feature article), 46, 8587–8623 (2005).

Directed Crystallization Precursor Structures in Polymers Benjamin S. Hsiao (Stony Brook University), DMR-0405432.

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AFM image of etched UHMWPE shish-kebab scaffold. Polymer (feature article), 46, 8587–8623 (2005).

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  1. Directed Crystallization Precursor Structures in PolymersBenjamin S. Hsiao (Stony Brook University),DMR-0405432 Flow-induced crystallization is an important subject in polymer processing. Varying processing conditions can produce different morphologies, which lead to different properties. The aim of this research is to investigate the events occurred at the earliest stages of flow-induced crystallization (i.e., the formation of shish-kebab like nanostructured scaffold). Using in-situ synchrotron SAXS techniques, we obtained several new insights into the formation, melting and reformation of the shish-kebab structure. (1) Under flow, stretched and coiled chain segments co-exist even in nearly monodispersed high molecular weight polyethylene chains. The different state of chain segments is caused by the deformation of the network structure in highly entangled polymer melt. (2) The stretched and coiled segments are responsible for the formation of the shish-kebab structure. (3) Upon heating, melting of macrokebabs takes place before melting of microkebabs and shish, which vanish simultaneously as an integrated entity into coiled and stretched chain segments. The shish-kebab structure can reform upon cooling, mainly due to the survival of stretched chain segments confined by the entanglement points (shown in the SAXS figure). AFM image of etched UHMWPE shish-kebab scaffold. Polymer (feature article), 46, 8587–8623 (2005). Reformation of shish-kebab scaffold by in-situ SAXS. Macromolecules, 39(6), 2209-2218 (2006).

  2. Directed Crystallization Precursor Structures in PolymerBenjamin S. Hsiao (Stony Brook University),DMR-0405432 Outreach Each summer, graduate students and post-doctoral scientists have participated in the summer high school student research program, sponsored by the Stony Brook University. In 2006, five high school students (Jeffrey Tam - Oceanside High School; Soo Jeong Kim - Jericho High School; Zachary Hollander - Great Neck North High School; Max Soni -Jericho High School and Sharon Ji - Wheatley High School) have been hosted in our laboratory, all of them will compete in the Intel Science Talent Search. Pictures of these high school researchers and their mentors are shown below. In addition, we have also hosted two undergraduate guest researchers from other schools: Joseph Gaiteri - King's College in PA, Matthew Windt - Texas A&M. Education Under this grant, two students have completed their Master degrees and will attend PhD programs in other universities: Ms. Priya Desai - Univ. Illinois-Urbana; Ms. Derya Cebeci - Purdue Univ.; ex-post-doctoral researcher, Dr. Igors Sics has accepted a beamline scientist position at CELLS synchrotron facility at Spain. Currently, two PhD graduate students (Mr. Feng Zuo and Mr. Jong Kahk Keum) are supported by this project. Other scientists involved in this research include: Dr. Rajesh Somani (senior scientist), Dr. Shigeyuki Toki (senior scientist), Dr. Lixia Rong (beamline scientist at X27C, National Synchrotron Light Source, Brookhaven National Laboratory)

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