Carbon nanotubes (CNTs) have drawn interest for many applications since their discovery. While they provide exceptional mechanical, physical and chemical properties, several technical barriers must be overcome before these properties can be fully used. Some of such drawbacks concern length control, lack of good dispersion and poor interfacial bonding. Currently, CNTs such as single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs) and carbon nanofibers (CNFs) are produced in lengths ranging between several to hundreds micrometers and are usually bounded into macroscopically entangled networks. This contradicts with the requirements of some applications, which in the end will benefit with short and highly dispersed CNTs in lengths of a few hundred nanometers or less, such as drug delivering and energy storage carriers. Short CNTs (s-CNTs) and CNFs (s-CNFs) can enhance the mechanical properties of a composite due to the increased interaction with the polymer matrix, through the improvement of the interfacial bonding and resin encapsulation, which is possible with existing open ends of nanotubes. Ultimately this influences the matrix's properties by affecting its chain entanglements, morphology, and crystallinity in the nanocomposite. This research is a continuous effort on nanoscale cutting and characterization of s-CNTs and s-CNFs. Moreover, this research used s-MWNTs and s-CNFs in the lengths of 200 and 500 nm to manufacture the nanocomposites. The mechanical properties of the resultant nanocomposties were characterized. The interactions of the s-MWNT and s-CNTs with epoxy resin matrix were observed using high-resolution SEM and atomic-resolution TEM. The results were compared to nanocomposites with pristine MWNTs and CNFs. In the study, four case studies were explored: 1) 200 nm s-MWNT/epoxy composites; 2) 500 nm s-MWNTs/epoxy composites; 3) 200 nm s-CNF/epoxy composites; 4) 500 nm s-CNF/epoxy composites. For all four cases the MWNT and CNF concentrations were 0.05 wt%, 0.10 wt%, and 1.00 wt%, respectively. Significant mechanical improvements were observed. The strength of the s-MWNT nanocomposite at 1.00 wt% gave a 64% improvement compared to the control sample. The highest young's modulus was also obtained in the 1.00 wt% s-MWNT (200 nm) nanocomposite, and it showed an increase of 44%. In general, the most significant improvements were seen with the s-MWNTs (200 nm) nanocomposites due to their smaller diameters and shorter length. Glass transition temperature was also studied. Finally, the interfacial bonding and interactions of the nanotube's opened ends with the resin matrix were observed through HR-SEM and atomic-resolution TEM analysis, which validated the creation of MWNT and CNF opened ends and the actual resin encapsulation inside the nanotubes' hollow structures. / A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements
for the degree of Master of Science. / Summer Semester, 2011. / April 27, 2011. / short carbon nanotubes, open ends nanocomposites / Includes bibliographical references. / Zhiyong Richard Liang, Professor Directing Thesis; Tao Liu, Committee Member; Chun Chuck Zhang, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_254100 |
| Contributors | Koo, Ana (authoraut), Liang, Zhiyong Richard (professor directing thesis), Liu, Tao (committee member), Zhang, Chun Chuck (committee member), Department of Industrial and Manufacturing Engineering (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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