All ETDs from UAB

Advisory Committee Chair

Daneesh Simien

Advisory Committee Members

Amber Genau

Clayton E Simien

Haibin Ning

Ruigang Wang

Document Type

Dissertation

Date of Award

2017

Degree Name by School

Doctor of Philosophy (PhD) School of Engineering

Abstract

ABSTRACT In this work, Single Walled Carbon Nanotubes (SWNT) were separated by length and chirality using an ultracentrifuge technique. The influence of length-separation on the composites’ viscosity and crystallinity behavior was studied. We found that the compo-sites’ viscosity does not increase monotonously with weight fractions. Specifically, in rel-atively small nanotube weight fractions, the dynamic viscosity of the composites was found to be smaller than that of the pure Polyisotublyene (PIB) matrix. The dimension of nanotube bundles and polymer radius of gyration were compared to further study the mechanism of such a viscosity change. It was observed that nanotubes with shorter lengths successfully initiated polymer crystallization. In further studies conducted on, both length and chirality separated SWNTs were used to fabricate nanotube based semi-conducting devices, the 1/f noise characteristics of all samples were measured and com-pared. It was experimentally observed that both length and chirality separation could ef-fectively reduce the level of noise in these homogenous samples. Finally, in coordinating the effects of nanoparticulate inclusions, with highly spe-cific dimensional, and dispersion characteristics the study of the extrusion processing of Polytetrafluoroethylene (PTFE)/ Styrene- Acrylonitrile Copolymer (SAN) nanocompo-sites is presented. As with the dimensional control observed with regards to the nanopar-ticulates in SWNT- polymer composites, which serves as a first order system model which has led to predictable structure-property relationships, the control of the dimension and morphology of nanofribrils produced in processing PTFE/SAN nanocomposites will deci-sively alter the overall properties and behavior of the whole composite. In this study, the degree of nano-fibrillaiton is quantified, and its relationship to increased mechanical properties of the composite is assessed. The accelerating pattern of fibrillation increase was identified, and the critical temperature to initiate a significant formation of nanofiber was identified.

Included in

Engineering Commons

Share

COinS