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Polyamide-imide and Montmorillonite Nanocomposites

Polyamide-imide and Montmorillonite Nanocomposites

Date: August 2001
Creator: Ranade, Ajit
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 studied by x-ray diffraction (XRD) and was confirmed by Transmission electron microscopy (TEM). Differential scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA) was used to study impact of MMT on glass transition temperature (Tg) and degradation properties of PAI respectively. Micro-hardness testing of PAI nanocomposites was also performed. A concentration dependent state of dispersion was obtained. The glass transition (Tg), degradation and mechanical properties were found to correlate to the state of dispersion.
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Polycyclic-Aromatic-Hydrocarbon-Induced Alterations in the Physio-Chemical Characteristics of Escherechia Coli Dexyribonucleic Acid

Polycyclic-Aromatic-Hydrocarbon-Induced Alterations in the Physio-Chemical Characteristics of Escherechia Coli Dexyribonucleic Acid

Date: August 1969
Creator: Chapel, J. Frederick (James Frederick)
Description: Prior to 1965 the interactions of polycyclic aromatic hydrocarbons with DNA (Deoxyribonucleic acid) had been but moderately studied. It was concluded that, although a controversy existed, an apparent interaction occurred between DNA and certain aromatic hydrocarbon molecules and that the interaction was not an artifact of the reaction system.
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Polyethylene-layered double hydroxide and montmorillonite nanocomposites: Thermal, mechanical and flame retardance properties.

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

Date: May 2008
Creator: Kosuri, Divya
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.
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Polymer Gels: Kinetics, Dynamics Studies and Their Applications as Biomaterials

Polymer Gels: Kinetics, Dynamics Studies and Their Applications as Biomaterials

Date: December 2003
Creator: Wang, Changjie
Description: The polymer gels especially hydrogels have a very special structure and useful features such as unusual volume phase transition, compatibility with biological systems, and sensitivity to environmental stimuli (temperature, pH value, electric field, light and more), which lead to many potential applications in physical and biochemical fields. This research includes: (1) the theoretical and experimental studies of polymer gels on swelling kinetics, spinodal decomposition, and solution convection in gel matrix; (2) applications of polymer gels in wound dressing, tissue-simulating optical phantom and gel display. The kinetics of gel swelling has been theoretically analyzed by considering coupled motions of both solvent and polymer network. Analytical solutions of the solvent and the network movement are derived from collective diffusion equations for a long cylindrical and a large disk gel. Kinetics of spinodal decomposition of N-isopropylacrylamide (NIPA) polymer gel is investigated using turbidity and ultrasonic techniques. By probing movement of domains, a possible time-dependent gel structure in the spinodal decomposition region is presented. Theoretical studies of solution convection in gel matrix have been done and more analysis on dimensionless parameters is provided. To enhance the drug uptake and release capacity of silicone rubber (SR), NIPA hydrogel particles have been incorporated into a SR ...
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Polymer hydrogel nanoparticles and their networks

Polymer hydrogel nanoparticles and their networks

Date: August 2002
Creator: Lu, Xihua
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 concentration, polymer concentration, and reaction temperature. The swelling and phase transition properties of resultant HPC microgels have been analyzed using both static and dynamic light scattering techniques. By first making gel nanoparticles and then covalently bonding them together, we have engineered a new class of gels with two levels of structural hierarchy: the primary network is crosslinked polymer chains in each individual particle, while the secondary network is a system of crosslinked nanoparticles. The covalent bonding contributes to the structural stability of the nanostructured gels, while self-assembly provides them with crystal structures that diffract light, resulting in colors. By using N-isopropylacrylamide copolymer hydrogel nanoparticles, we have synthesized nanoparticle networks that display a striking iridescence like precious opal but are soft and flexible like gelatin. This is in contrast to previous colored hydrogels, which were created either by adding dyes or fluorescent, ...
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Polymer Liquid Crystal (PLC) and Polypropylene Interlayers in Polypropylene and Glass Fiber Composites: Mechanical Properties

Polymer Liquid Crystal (PLC) and Polypropylene Interlayers in Polypropylene and Glass Fiber Composites: Mechanical Properties

Date: December 2000
Creator: Maswood, Syed
Description: In recent developments of composite materials, scientists and engineers have come up with fibers as well as matrices for composites and techniques of blending high cost components with low cost materials. Thus, one creates cost effective composite materials that are as efficient as space age components. One of the major breakthroughs in this area is the innovation of molecular composites, specifically polymeric liquid crystals (PLCs). These materials have excellent mechanical properties such as tensile impact and bending strength. They have excellent chemical resistance, low thermal expansivity, and low flammability. Their low viscosity leads to good processability One major setback in using space age composite technology in commercial applications is the price. Due to the complexity of processing, the cost of space composite materials is skyrocketing. To take the same concept of space age composite materials to create a more economical substitute has become a serious concern among scientists and engineers around the world. The two issues that will be resolved in this thesis are: (1) the potential impact of using PLCs (molecular reinforcement) can have on macro reinforced (heterogeneous composite, HC) long fiber systems; and (2) how strategic placement of the reinforcing layers can affect the macromechanical properties of the ...
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Polymorphous

Polymorphous

Access: Use of this item is restricted to the UNT Community.
Date: May 2004
Creator: Maxwell, Sarah
Description: The first section explores how far I could stretch dichotomy in formal terms, while maintaining a visually resonant image. I wanted to manipulate a superficial surface filtered through "natural forms" as seen in scientific imagery. By this I wanted to create access to a place where forms could play and imagination could wander. I was seeking to find a confluence in seemingly opposing forces that would coexist in the same work. The second section answers questions I had established for myself. The most important discovery I made was about the true nature of what I called a dichotomy in my work. The last section discusses the conclusions drawn from mounting the Master of Fine Arts Exhibition. I found that my interests resided more in investigating an already confluent dualism, as opposed to reconciling a conflicting dichotomy.
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Polynomial Curve and Surface Fitting

Polynomial Curve and Surface Fitting

Date: January 1968
Creator: Capps, Ann Dowdy
Description: The main problems of numerical analysis involve performing analytical operations, such as integration, differentiation, finding zeroes, interpolation, and so forth, of a function when all the data available are some samples of the function. Therefore, the purpose of this paper is to investigate the following problem: given a set of data points (x[sub i], y[sub i]) which are samples of some function, determine an approximating function. Further, extend the problem to that of determining an approximating function for a surface given some samples (x[sub i], y[sub j], z[sub ij]) of the surface.
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Polynomial Rings and Selected Integral Domains

Polynomial Rings and Selected Integral Domains

Date: January 1968
Creator: Kamen, Sam A.
Description: This thesis is an investigation of some of the properties of polynomial rings, unique factorization domains, Euclidean domains, and principal ideal domains. The nature of some of the relationships between each of the above systems is also developed in this paper.
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Polystylistic Features of Schnittke's Cello Sonata (1978)

Polystylistic Features of Schnittke's Cello Sonata (1978)

Date: August 2010
Creator: Kleinmann, Johannes
Description: Polystylism in Alfred Schnittke's music has been considered by scholars as a central aspect of his music. Although there are many published analyses of his choral music, symphonies, concerti and violin sonatas, there is no known published research for Schnittke's first cello sonata. Alfred Schnittke grew up in a culturally diverse environment influenced by many different composers and compositional styles under the restrictions of a communist Russian government. These aspects influenced the development of Schnittke's polystylism, characteristically represented by his Cello Sonata (1978). The detailed musical analysis of this sonata in this study serves the purpose to reveal Schnittke's polystylistic tendencies and his use of cyclic elements. These polystylistic elements in the sonata illustrate how Schnittke de-familiarizes listeners from rules commonly accepted as unavoidable and re-familiarizes listeners with the expressive qualities of tonal, twelve-tone and atonal music. Although Schnittke introduces polystylistic materials in de-familiarized contexts in this sonata, this study finds that Schnittke particularly re-familiarizes the audience's musical and stylistic perception through the reappearance of sections, textures and motifs. Abrupt polystylistic conflicts contrast with the repetition of previous materials, thereby forming a combination of traditional styles with features of discontinuity in 20th century music.
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