Experimental investigation of potting compound strength enhancement through the use of carbon nanomaterials
Carbon nanomaterials have recently been discovered which possess many unique physical properties. Multiple attempts have been made to integrate these materials into new technologies, including carbon nanocomposites with the goal of vastly improving the performance of these products. This thesis focuses on the incorporation of carbon nanofibers (CNF), multi-walled carbon nanotubes (MWNT), and buckminsterfullerene’s (buckyballs) into Cytec’s Corfil 625-1, an existing one-part potting compound. The goal was to improve the compressive strength of the material while maintaining the lap shear strength and keeping the density under that of a commercially available two-part potting compound, 3M’s EC-3500. The use of surfactants from BYK-Chemie led to an improvement in compressive strength of 45% when 5 wt% CNF was added. Carboxylic acid functionalization also showed improvement, however, CNF could not be added at a wt% as high as with the surfactant and a compressive strength enhancement of 11.5% was obtained. It was determined from SEM micrographs that preliminary mixing methods were breaking the glass balloons that were present in the 625-1 as provided by Cytec. As a result, the material was obtained without the microballoons and curing agent and new mixing methods were developed. The new compound allowed for greater flexibility in the mixing process, including higher shear and heating. It was also necessary to investigate the use of glass microballoons in order to replace what was not provided by Cytec. The use of S15 glass microballoons from 3M allowed for production of a potting compound similar to that of the 625-1 originally provided by Cytec. S38HS microballoons produced a one-part compound that was similar to the goal compound EC-3500. Sonication for 5 hours produced better results than the hand mixing that was initially performed, increasing the compressive strength of the potting compound by 21.7% when 1 wt% functionalized CNF was added to the compound. MWNT of various sizes were investigated, with the smallest diameter nanotube (8 nm) providing the best improvement. A three roll mill was utilized as a new mixing method that would reduce complications and allow for the process to be scaled up producing larger batches of carbon nanocomposite. The number of times the material was run through the mill was an important parameter and a 30.9% improvement was acquired when the composite went through 7 times.
Thesis (M.S) - Wichita State University, College of Engineering, Dept. of Mechanical Engineering