Articles by Dai Gil Lee in JoVE
Experimental Implementation of a New Composite Fabrication Method: Exposing Bare Fibers on the Composite Surface by the Soft Layer Method Dongyoung Lee1, Dai Gil Lee1, Jun Woo Lim2 1Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 2LANL-CBNU Engineering Institute Korea, Chonbuk National University A protocol to expose bare fibers on the composite surface by eliminating resin rich area is presented. The fibers are exposed during fabrication of the composites, not by the post surface treatment. The exposed carbon composites exhibit high electrical conductivity in the through-thickness direction and high mechanical property.
Other articles by Dai Gil Lee on PubMed
Nanometer-scale Surface Modification of Epoxy with Carbon Black and Electromagnetic Waves Nanotechnology. May, 2010 | Pubmed ID: 20388978 The surface morphology of polymers and polymer composites strongly influences both the adhesive bonding strength of composite structures and the electrical conduction through carbon fiber composites. Conventional surface modification techniques (such as mechanical abrading, chemical treatment, plasma treatment and flame treatment) not only damage the surfaces of polymers and polymer composites but also increase production cost. In this study, the surface of epoxy was modified by heating carbon black with electromagnetic waves in order to generate nanometer-sized grooves. A thermal transfer model was developed to investigate the generation mechanism of the grooves and the process variables. In the surface modification technique, electromagnetic waves and carbon black were used to improve both the bonding strength and the electrical conductivity of the composite in a fast and efficient way.
Interlocking Membrane/catalyst Layer Interface for High Mechanical Robustness of Hydrocarbon-membrane-based Polymer Electrolyte Membrane Fuel Cells Advanced Materials (Deerfield Beach, Fla.). May, 2015 | Pubmed ID: 25821122 A physical interlocking interface that can tightly bind a sulfonated poly(arylene ether sulfone) (SPAES) membrane and a Nafion catalyst layer in polymer electrolyte fuel cells is demonstrated. Owing to higher expansion with hydration for SPAES than for Nafion, a strong normal force is generated at the interface of a SPAES pillar and a Nafion hole, resulting in an 8-fold increase of the interfacial bonding strength at RH 50% and a 4.7-times increase of the wet/dry cycling durability.
Three-Dimensional Interlocking Interface: Mechanical Nanofastener for High Interfacial Robustness of Polymer Electrolyte Membrane Fuel Cells Advanced Materials (Deerfield Beach, Fla.). Jan, 2017 | Pubmed ID: 27862369 A scalable nanofastener featuring a 3D interlocked interfacial structure between the hydrocarbon membrane and perfluorinated sulfonic acid based catalyst layer is presented to overcome the interfacial issue of hydrocarbon membrane based polymer electrolyte membrane fuel cells. The nanofastener-introduced membrane electrode assembly (MEA) withstands more than 3000 humidity cycles, which is 20 times higher durability than that of MEA without nanofastener.