10 Matching Results

Search Results

Results: 1 - 10
open access

Preparation and Characterization of a Treated Montmorillonite Clay and Epoxy Nanocomposite

Description: Montmorillonite reinforced polymers are a new development in the area of nanocomposite materials. Since reinforcement of epoxy is important to the development of high strength adhesives and composite matrices, the introduction of montmorillonite to epoxy is of interest. Compositional effects on epoxy reactivity, on molecular relaxation, and on mechanical properties were investigated. Change in reactivity was determined by Differential Scanning Calorimetry. Tensile properties at room temperature… more
Date: December 2000
Creator: Butzloff, Peter Robert
Partner: UNT Libraries

Cure Kinetics and Processing Parameters of Neat and Reinforced High Performance Epoxy Resins: Evaluation of Techniques

Description: Kinetic equation parameters for the curing reaction of a commercial glass fiber reinforced high performance epoxy prepreg composed of the tetrafunctional epoxy tetraglycidyl 4,4-diaminodiphenyl methane (TGDDM), the tetrafunctional amine curing agent 4,4’-diaminodiphenylsulfone (DDS) and an ionic initiator/accelerator, are determined by various thermal analysis techniques and the results compared. The reaction is monitored by heat generated determined by differential scanning calorimetry (DSC). … more
Access: Restricted to UNT Community Members. Login required if off-campus.
Date: December 1999
Creator: Bilyeu, Bryan
Partner: UNT Libraries
open access

Epoxy + Liquid Crystalline Epoxy Coreacted Networks

Description: Molecular reinforcement through in-situ polymerization of liquid crystalline epoxies (LCEs) and a non-liquid crystalline epoxy has been investigated. Three LCEs: diglycidyl ether of 4,4'-dihydroxybiphenol (DGE-DHBP) and digylcidyl ether of 4-hydroxyphenyl-4"-hydroxybiphenyl-4'-carboxylate (DGE-HHC), were synthesized and blended with diglycidyl ether of bisphenol F (DGEBP-F) and subsequently cured with anhydride and amine curing agents. Curing kinetics were determined using differential scanning… more
Date: December 2000
Creator: Punchaipetch, Prakaipetch
Partner: UNT Libraries

Characterizaton of Triethoxyfluorosilane and Tetraethoxysilane Based Aerogels

Description: Aerogels are highly porous, low dielectric constant (low k) materials being considered by the semiconductor industry as an interlayer dielectric. Low k materials are needed to overcome capacitance problems that limit device feature sizes. Precursors triethoxyfluorosilane (TEFS) and tetraethoxysilane (TEOS) were used to prepare bulk aerogels. Samples were prepared by sol-gel methods, and then carbon dioxide supercritically-dried. Effects of varying the water to precursor ratio were studied with … more
Access: Restricted to UNT Community Members. Login required if off-campus.
Date: December 2001
Creator: Roepsch, Jodi Ann
Partner: UNT Libraries

Mineral-filled polypropylene: Improvement of scratch resistance

Description: A potential alternative to acrylonitrile-butadiene-styrene (ABS) and polycarbonate+ABS (PC+ABS), pigmented mineral-filled polypropylene (PP) finds an opening in automotive interior components such as instrument panels, knee bolsters, consoles, etc. Because of the lack of surface aesthetics, pigmented mineral-filled PP is experiencing a limitation to its acceptance in many applications. This study focuses on exploring various mineral fillers and additives in polypropylene to provide a material w… more
Access: Restricted to UNT Community Members. Login required if off-campus.
Date: December 2001
Creator: Khatib, Jamal F.
Partner: UNT Libraries

The Effects of Color Concentrate in Polyolefins.

Description: Throughout history consumer products were generally manufactured from wood and metal. They either had to hold their natural color or become subject to painting. When plastics entered the industry, it was recognized for its ease of shaping, re-usability, physical properties and its low cost. One of plastics' greatest benefits is its ability to hold a given color from within allowing it to avoid use of paint. This paper will give a brief overview on the effects of pigments when incorporated in a … more
Access: Restricted to UNT Community Members. Login required if off-campus.
Date: December 2001
Creator: Flora, Paul
Partner: UNT Libraries
open access

Techniques Utilized in the Characterization of Existing Materials for Improved Material Development

Description: It has become increasingly important to remain on the cutting edge of technology for a company to remain competitive and survive in today's high-tech industries. To do this, a company needs various resources dedicated to this cause. One of these resources is the use of existing materials, as starting points, for which improved materials can be based. For this, a company must rely on the characterization of existing materials to bring that base technology into their company. Through this evaluat… more
Date: December 2001
Creator: Withaeger, Gary
Partner: UNT Libraries
open access

Temperature dependent rheology of surfactant-hydroxypropyl cellulose solutions.

Description: The rheology of 1-8% hydroxypropyl cellulose (HPC) solutions has been studied in the temperature range of 20-45 degrees Celsius. The results showed that the relative viscosity at each HPC concentration decreases with increasing temperature. The relative viscosity decreases drastically at about 43 degrees Celsius due to a phase transition. The influence of anionic surfactant, sodium dodecylsulfate (SDS), induced gelation of a 2% HPC solution. The HPC solutions gelled at surfactant SDS concentrat… more
Date: December 2002
Creator: Snively, C. Todd
Partner: UNT Libraries
open access

The Electron Emission Characteristics of Aluminum, Molybdenum and Carbon Nanotubes Studied by Field Emission and Photoemission.

Description: The electron emission characteristics of aluminum, molybdenum and carbon nanotubes were studied. The experiments were setup to study the emission behavior as a function of temperature and exposure to oxygen. Changes in the surface work function as a result of thermal annealing were monitored with low energy ultra-violet photoelectron spectroscopy for flat samples while field emission energy distributions were used on tip samples. The change in the field emission from fabricated single tips expo… more
Date: December 2002
Creator: Sosa, Edward Delarosa
Partner: UNT Libraries
open access

Stability of Field Emitter Arrays to Oxygen Exposures

Description: The purpose of these experiments was to determine the degradation mechanisms of molybdenum based field emitter arrays to oxygen exposures and to improve the overall reliability. In addition, we also evaluated the emission current stability of gold-coated field emitter arrays to oxygen exposures. oxygen at 1x10-6 torr was introduced into the chamber through a leak valve for different lengths of time and duty cycles. To ensure identical oxygen exposure and experimental measurement conditions, ti… more
Date: December 2002
Creator: Godbole, Soumitra Kumar
Partner: UNT Libraries
Back to Top of Screen