学 术 报 告
时间：2009年12月22日下午2:30
地点：高分楼228 (学术报告厅)
1. Fundamental understanding of the relationship between tear property and orientation/crystal morphology -- A “Time-Resolved” Study of Tear Process
报告人：刘立志 博士
美国陶氏化学公司(Dow Chemical)资深研究专家
国际衍射数据中心(ICDD) 高分子委员会主席
2. Are you the one we are looking for?
-Informal discussion with a R&D hiring manager
报告人：孙彤 博士
陶氏化学公司亚太区研发部分析科学研发总监
Abstract
Tear is an important mechanical property of polymer films. There have been many investigations of tear mechanism on various films such as blown, biaxially oriented, cast and isotropic films. However, the actual mechanism of tear process is in question due to complex tearing process in plane stress condition. In fact, it is very difficult to carry out an in-situ study of morphology, structure, and orientation during a tear process, in order to understand the property-structure relationship. This is because the tear testing is a very fast deformation process and tear path can vary a lot, which makes it very difficult to monitor the structural change. As plastic deformation occurred during the tearing process of the polyethylene film, the residual deformation along the tear path is actually very close to the real deformation occurred during the tear testing. The information obtained from different locations perpendicular to the tear path can actually reflect the real-time structural change at the tear front. In the present work, tear path of torn polyethylene film samples were studied with X-Ray Diffraction (XRD) and Small-Angle X-ray Scattering (SAXS).
Intorduction of Dr. Lizhi Liu
Dr Lizhi Liu is Senior Research Specialist in Analytical Sciences. He is the global expert in X-ray diffraction, Small angle X-ray scattering (SAXS), Laser light scattering, and electron diffraction. Lizhi is the Chairman for Polymers Subcommittee for the International Centre for Diffraction Data (ICDD) and Adjunct Professor in Tianjin University, China.
Lizhi joined Dow in 2002 at Freeport, Texas. Since then he has worked with many project teams such as OBC, NOP PU, Versify, XLA fibers, PE Highlander, Renaissance Block Polymers, etc, with main research focus on the elucidation of structure-property relationship. He has led several business/CIF funded projects like:
- Morphology index study of superstructure and optical property of LLDPE/LDPE blend films,
- Crystal and Amorphous Orientation and Crystal domain Packing in OBC Fiber and Film products
-Time-Resolved Laser Light Scattering and X-ray Diffraction Study of Polymer Morphology and Structure during Uniaxial and Biaxial Deformation Processes at room and High Temperature.
Prior to joining Dow, Lizhi was Beamline scientist, NSLS, Brookhaven National Laboratory; Research Scientist in State University of New York at Stony Brook. From 1994-1997, Lizhi was Postdoctoral Fellow with world renowned professor Benjamin Chu in State University of New York at Stony Brook. Lizhi obtained his PhD in Polymer Science from Chinese Academy of Science in 1991.
Lizhi has published over 50 CRIs and 2 patents in Dow. He also has 57 papers published externally including 15 papers on Macromolecules/Physics review Letter/JACS, 14 papers on Polymer/JPS-part B, and 2 review papers.
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