FERROMAGNETIC COATING AND MAGNETIC ASSEMBLY OF CARBON NANOTUBES AS NANO-ADDITIVES INTO POLYMER MATRICES

Open Access
- Author:
- Ceneviva, Steven Michael
- Area of Honors:
- Aerospace Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Namiko Yamamoto, Thesis Supervisor
Philip John Morris, Thesis Honors Advisor - Keywords:
- Aerospace
Aerospace Engineering
Composites
Carbon Nanotubes
CNTs
Magnetic Assembly
Polymer Nanocomposite
Materials - Abstract:
- Ferromagnetic CNTs were developed and implemented as a magnetically responsive nanoadditive when dispersed within polymer matrices, to form multi-functional CNT-polymer nanocomposites. The CNT nano-additives are highly desirable because of their unique mechanical and multi-functional properties. CNT-integrated nanocomposites are highly desirable in the field of aerospace engineering for their lightweight and multi-functional properties. When implemented properly, the CNTs can improve interlayer mechanical strength, along with electrical and thermal conductivity. Currently, the aerospace industry relies on carbon fiber reinforced plastics (CFRPs) for commercial aircraft structure. Despite the high mechanical strength, CFRPs have weak interlaminar strength causing them to be prone to delamination. Additionally, the lack of conductivity often requires additional layers of metal mesh to protect the aircraft structure from electromagnetic interference or lightning strikes. Polymer nanocomposites with Ni-coated CNT additives provide the improved interlaminar strength and electrical conductivity to be a solution to these existing issues. However, their application has been limited due to poor property scaling and poor scalability. Thus, capability to organize and control nano-additives within polymer matrices in bulk is the essential step toward effective bulk application of these novel advanced polymer nanocomposites. More specifically, I developed and implemented a three-step process to achieve magnetically aligned CNTs, as shown in Figure 2.1,: 1) chemical vapor deposition (CVD) growth of vertically aligned, multi-walled CNTs, 2) low-temperature air plasma treatment to clean, etch, and functionalize CNTs, and 3) electron beam evaporation of ferromagnetic nickel (Ni) on functionalized CNT surfaces. The CNT growth, mostly vertically aligned morphology, was optimized by pre-conditioning of iron (Fe) catalyst layers using hydrogen (H2) gas. Low-temperature plasma treatment etched away the entangled section of CNTs, exposing CNT tips to be ready for Ni coating. The degree of functionalization and degradation by plasma treatment was characterized via x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The Ni-coating on CNTs was inspected using energy dispersive x-ray spectroscopy (EDS) about their morphology and vibrating sample magnetometer (VSM) about their magnetic properties. With the 80-nm-thick Ni coating, the CNTs were well dispersed and suspended within solutions (DI water and a polymer matrix), and CNT alignment along magnetic fields was successfully demonstrated using the small field (150 G) in a short time (15 mins). This preliminary result confirms the potential of Ni-coated CNTs as magnetically responsive additives that can be organized in bulk using an energy-efficient set-up.