Rheological and morphological characterization of hierarchically nanostructured materials
Name
166330521-MIT.pdf
Description
Full printable version
Size
19.55 MB
Format
Adobe PDF
Checksum (MD5)
e3906331b76ff862f3c344af146267c6
Author(s)
Wang, Benjamin Ning-Haw
Advisor(s)
Robert E. Cohen and Gareth H. McKinley.
Date Issued
2007
Publisher
Massachusetts Institute of Technology
Abstract
Hierarchically nanostructured materials exhibit order on multiple length scales, with at least one of a few nanometers. The expected enhancements for applications using these materials include improved mechanical, thermal and electrical properties; however, control of the morphology which governs material performance and fabrication remains a challenge. The development of novel quantitative characterization techniques is important to connect the underlying morphology to relevant processing parameters and macroscopic behavior. Rheological and morphological analysis can illustrate these governing structure-property relationships for hierarchically nanostructured materials based on "O-D" polyhedral oligomeric silsesquioxane (POSS) particles, "l-D" carbon nanotubes (CNTs), and "2-D" clay nanoparticles. We develop a technique, using small-angle X-ray scattering, which provides quantitative measurements of the morphological characteristics of CNT films, including shape, orientation, CNT diameter, and spacing between CNTs. The method reflects a locally averaged measurement that simultaneously samples from millions of CNTs while maintaining the necessary precision to resolve spatial morphological differences within a film.
(cont.) Using this technique we elucidate spatial variation in pristine films and study changes in the film structure as a result of mechanical manipulations such as uniaxial compression and capillarity-induced densification. We study the rheological properties of blends formed from POSS and clay nanoparticles incorporated into PMMA in shear and extensional flow fields. Relevant morphological parameters, such as volume fraction, aspect ratio of the clay particles, and POSS miscibility are determined using wide angle X-ray scattering and transmission electron microscopy. The interdependence between melt rheology and morphology are understood within a theoretical framework for percolated physical networks, providing for comprehensive guidance regarding the performance and processing of POSS and clay based nanocomposites.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2007.
Vita.
Includes bibliographical references (leaves 154-168).
Subjects
Chemical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
Terms of Use
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
Persistent DSpace Link
