지난 7월 6일 Drexel University 의 Ph.D candidate 두 분의 Speicial 세미나가 공업센터 본관 기계공학부 세미나실에서 있었습니다.
발표 주제 및 발표자는 아래와 같습니다.
Title : Surface Disinfection of Spacecraft Materials from Microorganisms using Non-Thermal Atmospheric Pressure Plasmas
Presentator : Moogega Cooper, Ph.D. Candidate
A. J. Drexel Plasma Institute
Dept of Mechanical Engineering & Mechanics
Current methods to achieve sterilization of the exterior surface of the spacecraft have several drawbacks including damage to and failure of electronic components, corrosion, and water absorption. The above problems can be eliminated by employing non-equilibrium atmospheric pressure plasmas. It is important that extraplanetary-bound landers and probes have ≤ 30 bacterial spores on the free surfaces of a landed system to prevent the proliferation of microorganisms beyond their original environment. The energized particles, UV radiation, and chemically active species generated in plasma can kill spores, bacteria and other microorganisms at low temperature without thermal and oxidative damage to the treated surfaces. Escherichia coli, Bacillus subtilis, and Deinococcus radiodurans have been inactivated and/or completely removed from the surface in the presented experiments using dielectric barrier discharge (DBD) plasma. Characterization of the destruction phases before and after plasma treatment was performed by collecting Scanning Electron Microscope (SEM) images. Cell viability measurements were performed by standard plating method. DBD is an effective mean by which to successfully inactivate bacteria and spores at low temperatures.
Title : Tailoring of Interfacial Properties in Fiber Reinforced Polymer Composites Using DBD Plasma
Presentator : Jacqueline Yim, Ph.D. Candidate
A. J. Drexel Plasma Institute
Department of Chemical & Biological Engineering
Hybrid materials such as fiber-reinforced polymer composites are ubiquitous in aerospace, automobile, structural, and ballistic applications. These materials can impart various mechanical responses such as toughening or energy absorbing properties based upon the interaction between the fiber and the polymer matrix. The interface created between the two materials is a key area of importance that ultimately reflects upon the performance of the composite. Depending upon the use of the composite, an optimal balance of adhesion strength and energy absorption properties is highly desired. Therefore, a practical method is needed where the tunability of the interface can be achieved. In this work, the use of dielectric barrier discharge (DBD) plasma was used to functionalize ultra-high molecular weight polyethylene (UHMW-PE) fibers to obtain surfaces that conform to the polymer matrix through the introduction of chemical reactive groups. Plasma treatments were carried out by varying conditions such as exposure time, plasma gas, and gas flow-rate. Plasma-treated fiber surfaces were characterized using surface analytical techniques that include attenuated total reflectance – Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS), and water contact angle (WCA) measurements to identify major chemical groups and to evaluate the degree of functionalization. Interfacial properties – shear strength and energy absorption were studied using a micromechanical test known as the microdroplet test. Results show that plasma treatments alone can be a promising technique that can be used to achieve a more controlled and tailored interface.
두 편의 Special 세미나 후 연구실 투어와 오찬자리가 있었으며, Drexel 대학의 플라즈마 연구에 관한 소중한 이야기를 들으며 의견을 교환할 수 있는 의미있는 자리를 가졌습니다.