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Polyethylene-layered double hydroxide and montmorillonite nanocomposites: Thermal, mechanical and flame retardance properties.

Description: The effect of incorporation two clays; layered double hydroxides (LDH) and montmorillonite layered silicates (MLS) in linear low density polyethylene (PE) matrix was investigated. MLS and LDH were added of 5, 15, 30 and 60 weight percent in the PE and compounded using a Brabender. Ground pellets were subsequently compression molded. Dispersion of the clays was analyzed using optical microscopy, SEM and XRD. Both the layered clays were immiscible with the PE matrix and agglomerates formed with increased clay concentration. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Both clays served as nucleation enhancers increasing recrystallization temperatures in the composites. Flame retarding properties were determined by using the flammability HVUL-94 system. LDH indicated better flame retarding properties than MLS for PE. The char structure was analyzed by environmental scanning electron microscopy. Mechanical properties were studied by tensile testing and Vickers microhardness testing apparatus.
Date: May 2008
Creator: Kosuri, Divya
Partner: UNT Libraries

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1993

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes technical progress of research and development efforts aimed at producing superconducting components in the Y-Ba-Cu, (B1,Pb)-Sr-Ca-Cu, (Tl,Pb,BI)-(Ba,Sr)-Ca-Cu, and Hg-Ba-Ca-Cu-O oxide systems including: synthesis and heat treatment of high-Ta superconductors; formation of monolithic and composite wires, tapes, and coils; characterization of structures and superconducting and mechanical properties; fabrication and properties of films; and development of prototype components.
Date: October 1993
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Development of a Boron-Copper Neutron Absorber Composite

Description: This report describes the fabrication of a new boron-copper neutron absorbing material that was developed to meet the upgrading needs of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory. To increase the intensity of the neutron beams from the IPNS, the target uranium was changed from depleted uranium to uranium enriched to 77.5% U-235. To keep the multiplication factor, k(sub eff) (number of fissions in one generation/number of fissions in preceding generation) at a safe level, a new neutron absorber material was needed. The previous materials, boral and cadmium, could not meet the new requirements and a search of the literature showed that no currently available material was acceptable.
Date: May 1991
Creator: Wiencek, T. C.; Thresh, H. R. & Summers, J. R.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1995

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes the technical progress of research and development efforts aimed at producing superconducting components in the (Bi,Pb)-Sr-Ca-Cu, (T,Pb,Bi,V)- (Ba,Sr)-Ca-Cu, and Y-Ba-Cu oxide systems including: synthesis and heat treatment of high-Te superconductors, formation of monolithic and composite conductors, characterization of structures and superconducting and mechanical properties, and fabrication and testing of prototype components.
Date: October 1995
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1991

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes technical progress of research and development efforts aimed at producing superconducting components based on the Y-Ba-Cu, BI-Sr-Ca-Cu, Bi-Pb-Sr-Ca-Cu, and TI-Ba-Ca-Cu oxide systems including: synthesis and heat treatment of high-Te superconductors, formation of monolithic and composite wires and tapes, superconductor/metal connectors, characterization of structures and superconducting and mechanical properties, and fabrication and properties of thin films.
Date: October 1991
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1990

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes technical progress of research and development efforts aimed at producing superconducting components based on the Y-Ba--Cu, Bi-Sr-Ca-Cu, Bi-Pb-Sr-Ca-Cu, and TI-Ba-Ca-Cu oxide systems including: synthesis and heat treatment of high-Ta superconductors, formation of monolithic and composite wires and tapes, superconductor/metal connectors, characterization of structures and superconducting and mechanical properties, and fabrication and properties of thin films.
Date: October 1990
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1994

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes technical progress of research and development efforts aimed at producing superconducting components in the Y-Ba-Cu, (Bi,Pb)-Sr-Ca-Cu, (Tl,Pb,Bi)-(Ba,Sr)-Ca-Cu, and Hg-Ba-Ca-Cu-O oxide systems including: synthesis and heat treatment of high-Ta superconductors, formation of monolithic and composite conductors, characterization of structures and superconducting and mechanical properties, and fabrication and testing of prototype components.
Date: October 1994
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1992

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes the technical progress of research and development efforts aimed at producing superconducting components that are based on the Y-Ba-Cu, Bi-Sr-Ca-Cu, Bi-Pb-Sr-Ca-Cu, and (Tl,Pb)-(Ba,Sr)-Ca-Cu oxide systems including: synthesis and heat treatment of high-Ta superconductors, formation of monolithic and composite wires and tapes, superconductor/metal connectors, characterization of structures and superconducting and mechanical properties, fabrication and properties of thin films, and development of prototype components.
Date: October 1992
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications Semiannual Report: October 1989-June 1990

Description: Progress report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report describes technical progress of research and development efforts aimed at producing superconducting components based on the Y-Ba-Cu, Bi-Sr-Ca-Cu, and Tl-Ba-Ca-Cu oxide systems.
Date: June 1990
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Thermal-Performance Study of Liquid Metal Fast Breeder Reactor Insulation

Description: Three types of metallic thermal insulation were investigated analytically and experimentally: multilayer reflective plates, multilayer honeycomb composite, and multilayer screens. Each type was subjected to evacuated and non-evacuated conditions, where thermal measurements were made to determine thermal-physical characteristics. A variation of the separation distance between adjacent reflective plates of multilayer reflective plates and multilayer screen insulation was also experimentally studied to reveal its significance. One configuration of the multilayer screen insulation was further selected to be examined in sodium and sodium oxide environments. The emissivity of Type 304 stainless steel used in comprising the insulation was measured by employing infrared technology. A comprehensive model was developed to describe the different proposed types of thermal insulation. Various modes of heat transfer inherent in each type of insulation were addressed and their relative importance compared. Provision was also made in the model to allow accurate simulation of possible sodium and sodium oxide contamination of the insulation. The thermal-radiation contribution to heat transfer in the temperature range of interest for LMFBR's was found to be moderate, and the suppression of natural convection within the insulation was vital in preserving its insulating properties. Experimental data were compared with the model and other published results. Moreover, the three proposed test samples were assessed and compared under various conditions as viable LMFBR thermal insulations.
Date: September 1980
Creator: Shiu, Kelvin Kwok-Kay
Partner: UNT Libraries Government Documents Department

Comparison of Costs for Solidification of High-Level Radioactive Waste Solutions: Glass Monoliths vs Metal Matrices

Description: A comparative economic analysis was made of four solidification processes for liquid high-level radioactive waste. Two processes produced borosilicate glass monoliths and two others produced metal matrix composites of lead and borosilicate glass beads and lead and super-calcine pellets. Within the uncertainties of the cost (1979 dollars) estimates, the cost of the four processes was about the same, with the major cost component being the cost of the primary building structure. Equipment costs and operating and maintenance costs formed only a small portion of the building structure costs for all processes.
Date: May 1981
Creator: Jardine, L. J.
Partner: UNT Libraries Government Documents Department

Practical Superconductor Development for Electrical Power Applications, Annual Report: 1988

Description: Annual report for the superconductor program at Argonne National Laboratory discussing the group's activities and research. This report documents research efforts aimed at producing superconducting components based on oxide systems.
Date: February 1989
Creator: Argonne National Laboratory. Materials and Components Technology Division.
Partner: UNT Libraries Government Documents Department

Charge Interaction Effects in Epoxy with Cation Exchanged Montmorillonite Clay and Carbon Nanotubes.

Description: The influence of charge heterogeneity in nanoparticles such as montmorillonite layered silicates (MLS) and hybrid systems of MLS + carbon nanotubes was investigated in cured and uncured epoxy. Epoxy nanocomposites made with cation-exchanged montmorillonite clay were found to form agglomerates near a critical concentration. Using differential scanning calorimetry it was determined that the mixing temperature of the epoxy + MLS mixture prior to the addition of the curing agent critically influenced the formation of the agglomerate. Cured epoxy samples showed evidence of the agglomerate being residual charge driven by maxima and minima in the concentration profiles of thermal conductivity and dielectric permittivity respectively. A hybrid nanocomposite of MLS and aniline functionalized multi walled nanotubes indicated no agglomerates. The influence of environmentally and process driven properties on the nanocomposites was investigated by examination of moisture, ultrasound, microwaves and mechanical fatigue on the properties of the hybrid systems. The results point to the importance of charge screening by adsorbed or reacted water and on nanoparticulates.
Date: May 2005
Creator: Butzloff, Peter Robert
Partner: UNT Libraries

High-Density Polyethylene/Peanut Shell Biocomposites

Description: A recent trend in the development of renewable and biodegradable materials has led to the development of composites from renewal sources such as natural fibers. This agricultural activity generates a large amount of waste in the form of peanut shells. The motivation for this research is based on the utilization of peanut shells as a viable source for the manufacture of biocomposites. High-density polyethylene (HDPE) is a plastic largely used in the industry due to its durability, high strength to density ratio, and thermal stability. This research focuses in the mechanical and thermal properties of HDPE/peanut shell composites of different qualities and compositions. The samples obtained were subjected to dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and mechanical tensile strength tests. TO prepare the samples for analysis, the peanut shells were separated into different mesh sizes and then mixed with HDPE at different concentrations. The results showed that samples with fiber size number 10 exhibited superior strength modulus of 1.65 GPa versus results for HDPE alone at 1.32 GPa. The analysis from the previous experiments helped to determine that the fiber size number 10 at 5%wt. ratio in HDPE provides the most optimal mechanical and thermal results. From tensile tests the highest modulus of elasticity of 1.33 GPa was achieved from the samples of peanut shells size number 10 in HDPE at 20%wt. ratio, while the results for HDPE alone were only of 0.8 GPa. The results proved the hypothesis that the addition of peanut shells to HDPE enhances both the thermal and mechanical properties of the composite.
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Date: May 2014
Creator: Londoño Ceballos, Mauricio
Partner: UNT Libraries

Electromagnetically Modulated Sonic Structures

Description: Phononic crystals are structures composed of periodically arranged scatterers in a background medium that affect the transmission of elastic waves. They have garnered much interest in recent years for their macro-scale properties that can be modulated by the micro-scale components. The elastic properties of the composite materials, the contrast in the elastic properties of the composite materials, and the material arrangement all directly affect how an elastic wave will behave as it propagates through the sonic structure. The behavior of an elastic wave in a periodic structure is revealed in its transmission bandstructure, and modification of any the elastic parameters will result in tuning of the band structure. In this dissertation, a phononic crystal with properties that can be modulated using electromagnetic radiation, and more specifically, radio-frequency (RF) light will be presented.
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Date: May 2014
Creator: Walker, Ezekiel Lee
Partner: UNT Libraries

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 indicated improved modulus and retention of strength of the epoxy matrix but a decreased elongation to failure. Depression of dry nanocomposite glass transition was observed for nanocomposites beyond 5% by weight montmorillonite. Samples that were saturated with water showed lower moduli due to the epoxy matrix. The greatest moisture absorption rate was found at 7%, the least at 3%.
Date: December 2000
Creator: Butzloff, Peter Robert
Partner: UNT Libraries

The Microbial Retting Environment of Hibiscus Cannabinus and Its Implications in Broader Applications

Description: Fiber-yielding plants is an area of increased interest due to the potential use in a variety of green-based materials. These biocomposites can be incorporated into multiple uses; for example, to replace building materials and interior vehicular paneling. The research here aims to focus in on the crop Hibiscus cannabinus for utilization into these functions. H. cannabinus is economically attractive due to the entire process being able to be accomplished here in the United States. The plant can be grown in a relatively short growth period (120-180 days), and then processed and incorporated in a biocomposite. The plant fiber must first be broken down into a useable medium. This is accomplished by the retting process, which occurs when microbial constituents breakdown the heteropolysaccharides releasing the fiber. The research aims to bridge the gap between the primitive process of retting and current techniques in molecular and microbiology. Utilizing a classical microbiological approach, which entailed enrichment and isolation of pectinase-producing bacteria for downstream use in augmented microbial retting experiments. The tracking of the bacteria was accomplished by using the 16S rRNA which acts as “barcodes” for bacteria. Next-generation sequencing can then provide data from each environment telling the composition and microbial diversity of each tested variable. The main environments tested are: a natural environment, organisms contributed by the plant material solely, and an augmented version in which pectinase-producing bacteria are added. In addition, a time-course experiment was performed on the augmented environment providing data of the shift to an anaerobic environment. Lastly, a drop-in set was performed using each isolate separately to determine which contributes to the shift in microbial organization. This research provided a much needed modernization of the retting technique. Previous studies have been subject to simple clone libraries and growth plate assays and next-generation sequencing will bring the understanding of ...
Date: May 2015
Creator: Visi, David K.
Partner: UNT Libraries

Electrical resistivity as a measure of change of state in substrates: Design, development and validation of a microprocessor-based system.

Description: Smart structures are relevant and significant because of their relevance to phenomena such as hazard mitigation, structural health monitoring and energy saving. Electrical resistance could potentially serve as an indicator of structural well-being or damage in the structure. To this end, the development of a microprocessor-based automated resistance measurement system with customized GUI is desired. In this research, a nodal electrical resistance acquisition circuit (NERAC) system was designed. The system hardware interfaces to a laptop, which houses a customized GUI developed using DAQFactory software. Resistance/impedance was measured using DC/AC methods with four-point probes technique, on three substrates. Baseline reading before damage was noted and compared with the resistance measured after damage. The device was calibrated and validated on three different substrates. Resistance measurements were taken from PVDF samples, composite panels and smart concrete. Results conformed to previous work done on these substrates, validating the effective working of the NERAC device.
Date: December 2009
Creator: Le, Dong D.
Partner: UNT Libraries