Mechanics of mass, energy and momentum transfer in complex textured materials at micro/nanoscales
by Raman, Srikar, Ph.D., UNIVERSITY OF ILLINOIS AT CHICAGO, 2010, 191 pages; 3417338

Abstract:

The aim of this work is the investigation of the physical properties associated with nanostructured materials for various advanced applications which include controlled drug release, pressure driven nanofluidics, spray cooling etc.

Polymer nanofibers (monolithic or core-shell) and turbostatic carbon nanotube bundles fabricated through electrospinning and co-electrospinning respectively were used as the key materials in this work. For controlled release applications, a model fluorescent dye Rhodamine 610 chloride, proteins, drugs or antigens encapsulated inside electrospun polymer nanofibers and its release to a buffer medium was analyzed. As a result of these experiments, it was discovered that the release process is limited by desorption process from nanopore surfaces. The experimental results were used as foundation as novel theory of release process and also allowed characterization of the relevant physical parameters of different compounds involved. In addition, thermal characterization of these electrospun polymer nanofibers was carried out to investigate their creep properties. The aim of this part was in the establishment of a detailed mechanism responsible for shrinkage of nanofiber mats at elevated temperatures and elucidation of its relation to the microscopic thermally-induced changes occurring in the polymer structure. In particular, thermal behavior of Poly(ϵ-caprolactone) (PCL), Poly(methylmethacrylate) (PMMA), Polyacrylonitrile (PAN) and Polyurethane (PU) in electrospun nanofibers and original pellets were studied using Differential Scanning Calorimetry (DSC) and linked to the onset of thermally-induced shrinkage of nanofiber mats.

The elctrospinning setup was then extended to Co-electrospinning process for fabricating Turbostratic Carbon Nanotube Bundles, for pressure driven flow of suspensions. Using a model water soluble compound, fluorescent dye Rhodamine 610 chloride, it was shown that deposit buildup on the inner walls of the delivery channels and its adverse consequences pose a severe challenge in implementing pressure-driven fluidic delivery through nano- and microcapillaries even in the case of homogeneous solutions.

The final work was in the investigation of the rheological properties of complex textured micro material, mainly gypsum slurries. Gypsum slurries experience rapid evaporation of water which causes them to solidify in a few seconds. It is therefore important to study their rheological properties for enhancing the efficacy of the production processes as well as to minimize the associated water content. Therefore, in this work, rheological characterization of gypsum slurries were studied under various initial conditions namely Water to Stucco Ratio, effect on rheological properties of the slurries due to the addition of foam and time related shear measurements.

 
AdviserAlexander L. Yarin
SchoolUNIVERSITY OF ILLINOIS AT CHICAGO
SourceDAI/B 71-08, p. , Aug 2010
Source TypeDissertation
SubjectsMechanical engineering; Nanotechnology
Publication Number3417338
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