UNT Libraries - 9 Matching Results

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Characterization of Methyltrimethoxysilane Sol-Gel Polymerization and the Resulting Aerogels.

Description: Methyl-functionalized porous silica is of considerable interest as a low dielectric constant film for semiconductor devices. The structural development of these materials appears to affect their gelation behaviors and impact their mechanical properties and shrinkage during processing. 29Si solution NMR was used to follow the structural evolution of MTMS (methyltrimethoxysilane) polymerization to gelation or precipitation, and thus to better understand the species that affect these properties an… more
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Date: August 2003
Creator: Dong, Hanjiang
Item Type: Refine your search to only Thesis or Dissertation
open access

Polymer hydrogel nanoparticles and their networks

Description: The thermally responsive hydroxypropyl cellulose (HPC) hydrogel nanoparticles have been synthesized and characterized. The HPC particles were obtained by chemically crosslinking collapsed HPC polymer chains in water-surfactant (dodecyltrimethylammonium bromide) dispersion above the lower critical solution temperature (LCST) of the HPC. The size distributions of microgel particles, measured by dynamic light scattering, have been correlated with synthesis conditions including surfactant concen… more
Date: August 2002
Creator: Lu, Xihua
Item Type: Refine your search to only Thesis or Dissertation

Thermal, Electrical, and Structural Analysis of Graphite Foam

Description: A graphite foam was developed at Oak Ridge National Laboratory (ORNL) by Dr. James Klett and license was granted to POCO Graphite, Inc. to manufacture and market the product as PocoFoam™. Unlike many processes currently used to manufacture carbon foams, this process yields a highly graphitic structure and overcomes many limitations, such as oxidation stabilization, that are routinely encountered in the development of carbon foam materials. The structure, thermal properties, electrical resistiv… more
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Date: August 2001
Creator: Morgan, Dwayne Russell
Item Type: Refine your search to only Thesis or Dissertation

Mechanical Properties of Polymer Modified Mortar

Description: The mechanical properties of the polymer-modified mortar are markedly improved over conventional cement mortar. We utilized recycled ABS in powder form and a polymer latex emulsion, polymer percentage ranges from 0 to 25 percent by polymer/cement ratio were investigated. The mechanical properties investigated were compression strength and adhesion strength. Compression strength effects did not have an impact on adhesion strength. Adhesion strength was calculated with pullout testing apparatus … more
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Date: August 2002
Creator: Palos, Artemio
Item Type: Refine your search to only Thesis or Dissertation
open access

Materials properties of hafnium and zirconium silicates: Metal interdiffusion and dopant penetration studies.

Description: Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric… more
Date: August 2002
Creator: Quevedo-Lopez, Manuel Angel
Item Type: Refine your search to only Thesis or Dissertation
open access

Polyamide-imide and Montmorillonite Nanocomposites

Description: Solvent suspensions of a high performance polymer, Polyamide-imide (PAI) are widely used in magnetic wire coatings. Here we investigate the effect that the introduction of montmorillonite (MMT) has on PAI. MMT was introduced into an uncured PAI suspension; the sample was then cured by step-wise heat treatment. Polarized optical microscopy was used to choose the best suitable MMT for PAI matrix and to study the distribution of MMT in PAI matrix. Concentration dependent dispersion effect was stud… more
Date: August 2001
Creator: Ranade, Ajit
Item Type: Refine your search to only Thesis or Dissertation

Mechanical behavior and performance of injection molded semi-crystalline polymers.

Description: I have used computer simulations to investigate the behavior of polymeric materials at the molecular level. The simulations were performed using the molecular dynamics method with Lennard-Jones potentials defining the interactions between particles in the system. Significant effort was put into the creation of realistic materials on the computer. For this purpose, an algorithm was developed based on the step-wise polymerization process. The resulting computer-generated materials (CGMs) exhibit… more
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Date: August 2003
Creator: Simoes, Ricardo J. F.
Item Type: Refine your search to only Thesis or Dissertation

Application of Thermomechanical Characterization Techniques to Bismuth Telluride Based Thermoelectric Materials

Description: The thermoelectric properties of bismuth telluride based thermoelectric (TE) materials are well-characterized, but comparatively little has been published on the thermomechanical properties. In this paper, dynamic mechanical analysis (DMA) and differential scanning calorimetry data for bismuth telluride based TE materials is presented. The TE materials' tan delta values, indicative of viscoelastic energy dissipation modes, approached that of glassy or crystalline polymers, were greater than ten… more
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Date: August 2002
Creator: White, John B.
Item Type: Refine your search to only Thesis or Dissertation
open access

Influence of design and coatings on the mechanical reliability of semiconductor wafers.

Description: We investigate some of the mechanical design factors of wafers and the effect on strength. Thin, solid, pre-stressed films are proposed as a means to improve the bulk mechanical properties of a wafer. Three-point bending was used to evaluate the laser scribe density and chemical processing effect on wafer strength. Drop and strike tests were employed to investigate the edge bevel profile effect on the mechanical properties of the wafer. To characterize the effect of thin films on stren… more
Date: August 2002
Creator: Yoder, Karl J.
Item Type: Refine your search to only Thesis or Dissertation
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