Carbon Nanotube Dispersion in Epoxy Nanocomposites with Clay
- PDF / 747,273 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 13 Downloads / 220 Views
1057-II20-15
Carbon Nanotube Dispersion in Epoxy Nanocomposites with Clay Lei Liu1, and Jaime Grunlan1,2 1 Materials Science and Engineering, Texas A&M University, 3003 TAMU, College Station, TX, 77843 2 Mechanical Engineering, Texas A&M University, 3123 TAMU, College Station, TX, 77843 ABSTRACT Clay particles were used to facilitate the dispersion and network formation of singlewalled carbon nanotubes (SWNTs) in an epoxy matrix. In the presence of clay, electrical conductivity increase and percolation threshold reduction for SWNT/epoxy composites were achieved simultaneously. These improvements are due to better SWNT dispersion, as evidenced by optical microscopy and scanning electron microscopy. Dynamic mechanical analysis (DMA) shows that mechanical properties of the composites without clay could be improved by clay addition. SWNTs appear to have an affinity for clay that causes them to become more exfoliated and better networked. INTRODUCTION Single-walled carbon nanotubes (SWNTs) are considered a promising candidate for high performance polymer composites due to their superior electrical [1], thermal [2], and mechanical properties [3]. However, nanotubes naturally form bundles due to strong intertubular van der Waals interaction, which is a hurdle on their practical application [4,5]. Chemical modification of nanotubes can be used to improve the interfacial interaction and overall dispersion/exfoliation [6,7]. Nevertheless, the atomic structural perfection of the nanotubes is impaired and composite electrical conductivity will suffer from this approach [8]. Noncovalent modification of nanotubes, such as the introduction of polymer surfactant [9], can benefit nanotube exfoliation and composite properties at the expense of mechanical properties [10]. A novel way to disperse nanotubes is to use secondary particles, such as ZrO2 [11], in which stable SWNTs suspensions in water can be obtained. But polymer composites were never produced accordingly. As wellknown nanofillers for polymer composites [12,13], natural clay particles are inexpensive and negatively charged, which give them great potential for use in SWNTs-filled composites [14,15]. EXPERIMENTAL METHODS Raw SWNTs used for this study were produced by the HiPco process and contain 27wt% iron impurity (provided by Carbon Nanotechnologies, Houston, TX). Bisphenol-F based epoxy resin (D.E.R 354), 1-methyl tetrahydrophthalic anhydride curing agent (ECA-100), and N,Ndimethylbenzylamine (≥99%) catalyst were obtained from The Dow Chemical Company (Midland, MI), Dixie Chemical (Houston, TX) and Aldrich (Milwaukee, WI), respectively. Natural montmorillonite clay (Cloisite® Na+) and organoclay (Cloisite® 15A and Cloisite® 30B) were provided by Southern Clay Products (Gonzales, TX).
The SWNT/clay/epoxy composites were made by suspending a given amount of SWNT and clay in 40ml of acetone followed by sonication at 50W for 20min using a VirTis Virsonic 100 Ultrasonic Cell Disrupter (SP industries, Warminster, PA). Epoxy resin, curing agent, and amine catalyst were then
Data Loading...
