美国威斯康星大学麦迪逊分校童立生教授学术报告

报告人：美国威斯康星大学麦迪逊分校童立生教授

报告1： Fabrication of Small Diameter Vascular Scaffolds: Mimicking the Structure and Properties of Native Blood Vessels

时间：2017年10月9日10:00

地点：综合1号实验楼602

A series of methods have been developed to fabricate small diameter vascular scaffolds (SDVSs) made of different biomaterials and various microstructures. These SDVSs aim to mimic the biological and biomechanical properties of native blood vessels. For example, thermoplastic polyurethane (TPU) and silk fib­roin were combined at different weight ratios to produce hybrid SDVSs with a wavy morphology and multiple layered structures using electrospinning with a novel col­lector. Efforts were also made to fabricate triple-layered SDVSs containing a braided silk tube as the middle layer sandwiched by an inner electrospun TPU layer and an outer freeze-dried TPU layer. These SDVSs not only exhibited a desirable toe region and a capacity for long-term usage under repeated dilatation and contraction, they also demonstrated high cell viability and good biocompatibility with human endothelial cells.

报告2：Super- and Sub-Critical Gas-Assisted Processing and Foaming to Enhance the Exfoliation of Nanofillers in Polymer Nanocomposites

时间：2017年10月10日10:00

地点：综合1号实验楼602

Supercritical fluid (SCF) has been shown to facilitate the intercalation and exfoliation of nanoclay in the microcellular injection molding of polyamide-6 (PA6) nanocomposites. With the assistance of SCF, even in the absence of favorable interactions between the polymer and the nanoclay—such as in the absence of chemical compatibility, interlayer surfactant, and/or nanoclay surface treatment—intercalated structures can still be produced. In the microcellular injection molding process, SCF penetrates easily into the gallery of intercalated nanoclays and diffuses readily into the polymer matrix. SCF also plasticizes polymers very efficiently and increases the mobility of the polymer molecules. As more small SCF molecules and more polymer molecules enter the clay gallery, the platelets are pushed apart, losing their ordered crystalline structure and becoming disordered. Recent studies have also demonstrated that even in the sub-critical state, a physical blow agent such as CO₂ could effectively disperse graphene nanoparticles (GNPs) in polypropylene (PP) using a twin-screw extruder equipped with a simple gas injection unit consisting of a standard gas cylinder, a regulator, a valve, and a metal hose. The addition of CO₂ into the melt at pressures below the supercritical point would still allow foam­ing to occur within the barrel of the extruder and in the extrudate upon exiting from the die. Foam­ing introduces an equibiaxial flow on the surface of the expanding bubbles. This exten­sional flow imparts a stress greater than the shear case alone. The combination of shear and elongational stresses from flow and foaming eventually break up the nanofillers and facilitate the dispersion of nanofillers in the polymer matrix. Sam­ples processed with super- and sub-critical blowing agents showed increased exfoliation and dispersion as observed via electron microscopy, thermal analysis, Raman spectroscopy, and X-ray diffraction. The sub-critical gas-assisted processing (SGAP) method could be used as an alternative to super­critical fluid-assisted processing.

报告人简介：

Professor Lih-Sheng (Tom) Turng received his B.S. degree in Mechanical Engineering from the National Taiwan University, and his M.S. and Ph.D. degrees from Cornell University (with the Cornell Injection Molding Program, CIMP). He worked at C-MOLD developing advanced plastics processing simulation software and Knowledge Management System (KMS) for 10 years before joining the University of Wisconsin–Madison in 2000. His research encompasses novel processes, new materials, and advanced analysis on materials processing. He has been working in the area of injection molding and microcellular injection molding, and has extended his research into nanocomposites, bio-based polymers, nanocellulose nanocomposites, tissue engineering scaffolds, and digital design and manufacturing. He has received numerous grants and awards, including the National Science Foundation (NSF) Major Research Instrumentation (MRI) Award, NSF Academic Program Awards, NSF Industry/University Cooperative Research Center (I/UCRC) grant, an Industrial Consortium, Wisconsin Innovation & Economic Development Research Program awards, Wisconsin Alumni Research Foundation (WARF) Accelerator Program awards, as well as grants from the Department of Defense (DOD), Department of Agriculture (USDA) Agriculture and Food Research Initiative (AFRI), the Environmental Protection Agency (EPA), and the National Heart, Lung, and Blood Institute (NHLBI). He was the PI of four NSF and New York State Small Business Innovation Research (SBIR) Phase I and Phase II awards during his tenure in the industry.

Professor Turng holds the Kuo K. and Cindy F. Wang Professorship and the Vilas Distinguished Achievement Professorship and is the Co-Director of the Polymer Engineering Center at UW-Madison, a Fellow member of the American Society of Mechanical Engineers (ASME) and the Society of Plastics Engineers (SPE), the recipient of the 2015 Plastics Educator of the Year Award from the SPE Milwaukee Section, 2011 Engineer of the Year award from the SPE Injection Molding Division, and an Honored Service Member (for distinguished services and contributions to the society) of the SPE. Professor Turng has published over 200 peer-reviewed journal papers since joining UW-Madison in 2000 and has authored or edited many books, book chapters, patents, conference proceedings, and special issue journals. He has served as the editorial boards of a variety of international journals and the Board of Directors of the Injection Molding Division of SPE. Professor Turng has recently been selected to lead an interdisciplinary team at the Wisconsin Institute for Discovery (WID) to develop innovative tissue engineering scaffolds that restore, maintain, or improve the function of diseased or damaged human tissues. He is also the University of Wisconsin–Madison representative for the DOD Digital Manufacturing and Design Innovation Institute (DMDII) project, one of the National Network for Manufacturing Innovation (NNMI) institutes.