Master of Science, The Ohio State University, 1967, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Environmental Science, Miami University, 2018, Geology and Environmental Earth Science

Pharmaceuticals and endocrine disrupting compounds (EDCs) in the aquatic environment have been recognized as an emerging issue of environmental research. Wastewater treatment plants (WWTPs) receive a large spectrum of organic contaminants, which are in part eliminated during treatment. The inefficient removal of pharmaceuticals and EDCs by current wastewater treatment systems results in the occurrence of these compounds in different aquatic environments. Discharges of municipal sewage effluents are therefore considered as a main source of environmental pollution by pharmaceutical and EDC. We are therefore interested in the feasibility of using palygorskite-montmorillonite (Pal-Mt) clay particles and its surfactant modified forms as potential adsorbents for removing pharmaceuticals and EDCs from wastewater. In this study, batch equilibrium studies using surfactant-Pal-Mt and column studies using unmodified Pal-Mt for the removal of several pharmaceuticals and EDCs were studied. An enhanced sorption is observed for bisphenol A, carbamazepine, ibuprofen and sulfamethoxazole by the cetyltrimethylammonium bromide (CTAB) modified adsorbent with sorption capacity ranging from 9.58 x 10^3 – 4.89 x 10^4 mg/kg. However, a high sorption capacity of 1.73 x 10^4 mg/kg is reported for atenolol by the unmodified Pal-Mt due to electrostatic attraction. For the column studies, an increase in column length or a decrease in initial concentration of the adsorbate increased the breakthrough time. The adsorption capacity, and the time required to reach 50% breakthrough time, varied inversely and linearly to the volumetric flow rate.

Committee: Jonathan Levy (Advisor); Krekeler Mark (Committee Member); Danielson Neil (Committee Member) Subjects: Environmental Science; Environmental Studies; Water Resource Management

Doctor of Philosophy, The Ohio State University, 1969, Graduate School

Committee: Not Provided (Other) Subjects: Mineralogy

Doctor of Philosophy, Case Western Reserve University, 2015, Macromolecular Science and Engineering

Aerogels are an interesting class of materials that possess many exotic and extreme properties. These properties are developed as the gel network is produced from solution. As the gel develops, it builds a hierarchical structure, possessing architectures at different size scales through molecular and macro-scale interactions. Once the solvent is removed, and the resultant aerogel is produced, the hierarchical nature of the material produces many desirable properties including: extremely high porosities (greater than 90% pore volume)[1], extremely low thermal conductivities (10-30 mW/m-k)[1], very low densities (as low as 0.002 g/cm3)[2], low refractive indices (as low as 1.01),[3] low dielectric constants (between 1.0 and 1.5),[4] high surface areas,[5,6] and the slowest speed of sound through a solid material. The first chapter of this thesis deals with the structure/property relationships of polymer/clay aerogels interfused with uniformly distributed air bubbles were examined. Through the incorporation of a polyelectrolyte in a montmorillonite (MMT) clay solution, the viscosity was systematically changed by the addition of ions with different charges. The bubbles were achieved via high speed mixing and were stabilized through the use of the surfactant sodium dodecyl sulfate (SDS). As the charge of the ion increased from +1 (Na+ ions) to +2 (Ca2+ ions) to finally +3 (Al3+ ions), the modulus of the resultant aerogels increased. The foamed polymer/clay aerogels showed a reduction in thermal conductivity while retaining similar mechanical properties to unfoamed polymer/clay aerogels. The most promising composition was one which contained 5% MMT clay/5% poly(vinyl alcohol)/0.5% xanthum gum/0.5% SDS/0.2% Al2(SO4)3·6(H2O) possessing a density of 0.083 g/cm3, an average modulus of 3.0 MPa, and a thermal conductivity of 41 mW/m·K. The second project investigated the feasibility of incorporating ground recycled polyurethane (PU) foam into clay/polymer aerog (open full item for complete abstract)

Committee: David Schiraldi Ph.D. (Advisor); Mary Ann Meador Ph.D. (Advisor); Gary Wnek Ph.D. (Committee Member); Eric Baer Ph.D. (Committee Member) Subjects: Aerospace Materials; Automotive Materials; Chemistry; Engineering; Experiments; Inorganic Chemistry; Materials Science; Organic Chemistry; Polymer Chemistry; Polymers

Doctor of Philosophy, Miami University, 2015, Geology and Environmental Earth Science

This dissertation investigates the iron reduction-oxidation (redox) cycle and microbe-mineral interactions in clay minerals associated with sediments samples from the oxic-anoxic interface of a sediment core located in the 300 area of the Hanford site, Washington State, USA, in the summer of 2008. The applicability of the products of this redox reaction towards environmental problems such as heavy metal (Cr6+ Tc(VII) or U(VI)) contaminants is largely unexplored. This dissertation, therefore, seeks to develop a fundamental understanding of how redox cycled sediment samples can reduce/immobilize aqueous hexavalent chromium (Cr6+). These results are important for our understanding of how various clay minerals associated with sediment samples may be utilized to reductively immobilize heavy metal contaminants in the environment. The first subproject involves research on iron biogeochemistry in different clay minerals [nontronite (NAu-2), montmorillonite (SWy-2) and chlorite (CCa-2)] and size fractionated sediments [0.5- 2.0 µM (Hanford-C), 0.02-0.5 µM (Hanford-F)]. NAu-2 and SWy-2 were most effective in reducing Cr6+. Characterization of the Cr-clay reaction product utilizing scanning electron microscopy (SEM) with a focused ion beam (FIB) and transmission electron microscope (TEM) with electron energy loss spectroscopy (EELS) revealed that reduced chromium possibly formed as a subnanometer Cr2O3 as micro-aggregates in association with residual clay minerals. The second subproject focused on Fe redox cycling in size fractionated sediments. The rate and extent are determined as a result of structural Fe concentration and physiochemical properties of the clay minerals in association with sediment. The rate and extent of bioreduction decreased with increased cycle numbers with some variations. X-ray diffraction (XRD) and SEM revealed that biogenic quartz and clinoptilolite formed as secondary minerals as a result of dissolution-precipitation. The thi (open full item for complete abstract)

Committee: Hailiang Dong (Advisor); Jin-Wook Kim (Other); John Rakovan (Committee Member); Mark Krekeler (Committee Member); Jon Scaffidi (Other) Subjects: Biogeochemistry; Environmental Geology; Geochemistry; Geotechnology; Inorganic Chemistry; Rehabilitation; Soil Sciences

Doctor of Philosophy, Miami University, 2015, Geology and Environmental Earth Science

Water resources contamination by pharmaceutically-active and endocrine-disrupting compounds (EDCs) is widespread. Sewage treatment plants (STPs) are the main gateway of these compounds to the natural environment, posing acute and chronic health risks to aquatic organisms once discharged to rivers and streams as well as a potential human health concern through induced infiltration to municipal groundwater supplies. Concentrations of many of these compounds in the environment tend to be very low; however, the ecosystem and human health effects associated with chronic exposure to low-level concentrations are unknown. Also unknown are the effects when a synergic mix of these compounds and other chemicals that are consumed over a long period of time. There is therefore a need to research cost-effective, innovative alternative treatment technologies to remove pharmaceuticals and EDCs from STP effluent. Sorption is one of the main treatment mechanisms that is employed in sewage- and drinking-water treatment plants due to its low cost, simplicity and effectiveness. This dissertation used batch kinetic and batch equilibrium sorption-desorption experimental approaches to explore the use of the palygorskite-montmorillonite (PM) mix of clay minerals as a function of granule size for removing a selected group of pharmaceuticals and EDCs. This optimization based on granule size is mainly to maximizing both water-flow through the medium while still achieving significant retention of the compounds under common sewage effluent and environmental conditions (pH, ionic strength and temperature). This project also focused on improving the sorptive removal capacity of PM through surfactant-intercalation of PM for a selected group of pharmaceuticals and EDCs. Results from the batch experiments were fit to appropriate kinetic and equilibrium sorption models. For those compounds that followed a Langmuir equilibrium isotherm, a best fit-kinetic model was related to the Langmuir kinetics. (open full item for complete abstract)

Committee: Jonathan Levy PhD (Advisor); Mark Krekeler PhD (Committee Co-Chair); Neil Danielson PhD (Committee Member); Hailiang Dong PhD (Committee Member); Samuel Mutiti PhD (Committee Member) Subjects: Environmental Geology; Environmental Studies; Geology; Hydrologic Sciences; Hydrology; Water Resource Management

Master of Science (MS), Wright State University, 2011, Biochemistry and Molecular Biology

Wound healing is a complex, multi-step process that can be summarized into three stages, namely hemostasis and inflammation, proliferation, and finally tissue remodeling. Battlefield wound healing demands rapid hemostasis using clotting or cauterizing agents to immediately limit blood loss, but this occurs at the expense of proper tissue repair beyond hemostasis. Layered silicate clays such as kaolin and montmorillonite (MMT) have been previously shown to induce blood clotting due to their ability to form charged interactions with clotting factors. The charge characteristics of sodium MMT (Na-MMT) also enable functionalization with active biomolecules. Herein we first functionalize three types of alumoinosilicate clays, namely Na-MMT, kaolin, and halloysite with horseradish peroxidase (HRP) as a model system with which to study the binding and biological activity of biomolecules bound to MMT. We then functionalized Na-MMT with epidermal growth factor (EGF) via ion exchange reaction to create a nanocomposite (MMT-EGF) with EGF occupying approximately 0.12 % of the Na+ exchange sites and conduct biochemical analysis of keratinocytes after treatment with MMT-EGF. Our results demonstrate that EGF immobilized on MMT retains the ability to activate the epidermal growth factor receptor (EGRF), causing phosphorylation of the AKT and MEK1 pathways, as well as upregulation of its downstream target gene expression involved in cell growth and migration. This study also shows that like EGF, MMT-EGF treatment can stimulate cell migration in vitro, which is dependent on ERK1/2 phosphorylation.

Committee: Madhavi Kadakia PhD (Advisor); Rajesh Naik PhD (Advisor); Lawrence Prochaska PhD (Committee Member) Subjects: Biochemistry

Master of Science (MS), Wright State University, 2008, Earth and Environmental Sciences

Using batch and stream recirculating flume experiments to compare and contrast one clayey sediment (Warden Ditch) and two analytical grade clay minerals (montmorillonite and kaolinite), the dynamic interactions between two aquatic stressors (suspended solids and nickel) were explored. Aldrich humic acid was incorporated to demonstrate the mitigating effects of dissolved organic carbon (DOC) on Ni toxicity. The flux of Ni between compartments (dissolved and sorbed) was quantified as a partition/distribution coefficient. The USEPA test organism Daphnia magna (neonates, < 24 h) was utilized to evaluate toxicity in dynamic non-renewal, short-term bioassays. Generally, toxicity showed a linear relationship with turbidity level. Conversely, sorption coefficients were experiment specific, making them difficult to predict and assess. Clay functioned as an adsorbent, scavenging Ni. Results support the hypotheses that solids and metals act as stressors in streams, DOC attenuates the toxicity of Ni, and Ni fluxes quickly between system compartments.

Committee: G. Allen Burton PhD (Committee Chair); David Dominic PhD (Committee Member); Songlin Cheng PhD (Committee Member); Chad Hammerschmidt PhD (Committee Member) Subjects: Earth; Environmental Science; Geology; Toxicology

PhD, University of Cincinnati, 2008, Engineering : Materials Science

This research work focuses on the synthesis characterization and processing of conducting polymer coated both carbon fiber and montmorillonite clay based nano-particles to improve the mechanical, thermal, and adhesive properties of epoxy based micro and nano composites. The entire research work mainly consists of two parts. In the first part, homogeneous and uniform coatings of polyaniline were successfully deposited onto carbon fibers by aqueous electrodeposition technique using p-toluene sulfonic acid as the electrolyte. Electrochemical deposition of aniline was carried out by cyclic voltammetry in the potential range of -0.2 V to 1.0 V vs. SCE. The electrochemical deposition parameters such as the number of cycles, scan rate (SR), initial monomer ([M]) and electrolyte concentration ([E]) were systematically varied. The amount of composite coatings on carbon fibers was dependant on the electrochemical deposition parameters. From the weight gain analysis, rate of the reactions (Rp) were calculated. As the aniline concentration was increased up to 0.35 M and electrolyte concentration up to 0.5 M, the deposition rate also increased, whereas an increase in scan rate decreased the deposition rate. The kinetic analysis showed that the rate equation for the p-toluene sulfonic acid system is Rp ∝ SR-1.25 [M]0.73 [E]0.95. IR spectra also show an increase in the deposition of polyaniline coatings on carbon fibers with a decrease in the scan rate and an increase in both monomer and electrolyte concentration. The ratio of two oxidation states of polyaniline namely emeraldine and pernigraniline obtained during electrodeposition can be varied by changing the electrochemical deposition parameters. SEM results show that carbon fiber surface was uniformly coated with polyaniline resulting a dense, rough and reactive surface that increases the compatibility and wettability of carbon fibers. The effect of PANi coated carbon fibers on the curing behavior of diglycidyl ether of bisphe (open full item for complete abstract)

Committee: Jude Iroh PhD (Committee Chair); Relva Buchanan PhD (Committee Member); Steven Clarson PhD (Committee Member); Rodney Roseman PhD (Committee Member) Subjects: Engineering; Materials Science; Polymers

MS, University of Cincinnati, 2004, Arts and Sciences : Chemistry

The purpose of this study was to decrease chemical permeation of model compounds through calcium alginate film by adding small amounts of Montmorillonite (MMT) clay. In order to ensure maximum effectiveness of the clay it is crucial for MMT to be sufficiently exfoliated. During exfoliation MMT platelets are separated, thus increasing surface area improving dispersion within the calcium alginate matrix. The extent of exfoliation was verified by Light scattering particle-sizing and X-ray diffraction. Sodium alginate polymer solutions were blended with 0 to10% pre-exfoliated MMT on a dry weight basis to investigate the effect MMT has on alginate permeability. The polymer blends were cast into thin films and dried. The sodium alginate films were crosslinked with calcium chloride solution forming the water insoluble calcium alginate. The MMT impregnated calcium alginate films were subjected to permeation study to determine model chemical permeation. A Hanson Research diffusion cell was used to study the model permeation of a chemical across the calcium alginate membranes. Ultraviolet (UV) absorbance was used to determine the concentration of the model chemical that crossed the alginate membrane. Benzaldehyde was used for the model chemical due to its high UV absorbance and favorable oil to water partition coefficient. Accumulated benzaldehyde concentrations were then used to calculate diffusion coefficients for benzaldehyde within each film. The results indicate exfoliated MMT addition decreased the permeability of calcium alginate polymer membranes. The data show that addition of 0.5% clay yields decreased permeation compared to nascent calcium alginate film by approximately 2.5X. MMT clay amounts above 3% show a complicated clay concentration dependence, but were generally smaller than those of a calcium alginate film with 0% clay.

Committee: Dr. James Mark (Advisor) Subjects: Chemistry, Polymer

PhD, University of Cincinnati, 2003, Engineering : Materials Science

In-situ polymerization was used to synthesize a novel nanocomposite material based on layered silicate clay and intrinsically conducting polymers (ICPs): polyaniline (PANi). Conducting polymers including PANi and PPy are known to effectively protect active metals against corrosion. Montmorillonite (MMT) clay was successfully incorporated into polyaniline to form PANi-clay (PACN) nanocomposites with controlled structure and with improved properties. The relationship between the synthesis conditions and the structure, thermal behavior and oxidation states of the PANi-clay nanocomposites were determined and a further insight into the processing, structure and property correlations was gained. The effect of processing parameters such as oxidant and filler concentration on the structure and properties of the nanocomposites were studied by using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) together with thermal analysis. It was shown that the oxidant concentration plays an important role in controlling the properties and the structure of the PACN. It was shown that the degradation temperature of PACN decreases with the increasing concentration of oxidant. In depth study was done by FTIR to determine the molecular structure and the oxidation state of PANi in the composites. The morphology of the nanocomposites was observed by using the scanning electron microscopy (SEM). Transmission electron microscopy (TEM), wide-angle X-ray scattering and small angle X-ray scattering (SAXS) study showed the presence of both intercalated and exfoliated clay in the polymer matrix. X-ray diffraction analysis provides additional structural information on both PANi and PACN nanocomposites synthesized at different processing conditions. The nanocomposites were combined with epoxy and formulated into coatings for use in the protection of AA 2024-T3. The effect of PACN nanocomposites on the curing of epoxy resin was studied by using FTIR and a significant enhanceme (open full item for complete abstract)

Committee: Dr. Jude O. Iroh (Advisor) Subjects: Engineering, Materials Science

PhD, University of Cincinnati, 2001, Arts and Sciences : Chemistry

This work focused on examining and characterizing the reinforcement of thermoset and thermoplastic elastomers, such as natural rubber, epoxidized natural rubber and elastomeric polypropylene. The reinforcement was achieved through the formation of composites of these elastomers with reinforcing fillers by applying some of the latest techniques. One of the techniques is the combination of elastomeric materials with thermosetting resins, specifically natural rubber and cardanol-formaldehyde resins, to improve mechanical properties, such as toughness and thermal properties, such as high-temperature resistance. The natural product cashew nut shell liquid was used to obtain the cardanol, which was then used to prepare cardanol-formaldehyde (CF) resole and novolak resins. The curing behavior of systems containing natural rubber and cardanol-formaldehyde resins was established. The incorporation of cardanol-formaldehyde resins into natural rubber provided significant improvements in tensile strength, while maintaining the thermal stability of the elastomer. Various nanocomposites of epoxidized natural rubber, cis-1,4 polyisoprene and elastomeric polypropylene were successfully prepared by using montmorillonite clays as a reinforcing filler. Conditions were established for dispersing clay nanolayers into these elastomers. The clay filler-elastomer and clay filler-filler interactions were studied by using dynamic mechanical analysis. Such interactions were found to strongly depend on the clay organic modifiers and the polarity of the elastomers was found to have a major effect on the final properties of these nanocomposites. The dispersion of clay fillers into the elastomer matrix was examined by X-ray diffraction techniques. Mechanical property measurements showed that several organo-clays provided very strong reinforcing effects. For non-polar elastomers, organo-modified clays were found to behave more like "carbon black". For polar elastomers, the intercalation of the ela (open full item for complete abstract)

Committee: Dr. James E. Mark (Advisor) Subjects: Chemistry, Polymer

Master of Science in Chemical Engineering, University of Toledo, 2010, Chemical Engineering

Polymer nanocomposites are prepared by dispersing small quantities (0.5-10% by weight) of nano-sized particles which have high aspect ratios (100-1500) and high surface area (in excess of 750-800 m2/g) into the polymer matrices. Polymer nanocomposites offer improvements over conventional composites in mechanical, thermal and barrier properties without substantially increasing the density or affecting the light transmission properties of the base polymer. The objective of this project is to develop a new process for preparation of polyethylene terephthalate (PET)/montmorillonite (MMT/Na+MMT) nanocomposite and to characterize it. During the study, we tried to disperse natural clay (Na+MMT) in PET polymer monomers by different methods. Natural MMT clay has been chosen to prepare PET nanocomposites because previous studies with organoclays have shown that organically modified clays get thermally degraded at PET preparation and processing temperatures (~280 °C) and because of degradation, PET nanocomposites do not show expected improvement in properties. PET nanocomposites were prepared by dispersing pristine MMT (Na+MMT) clays into ethylene glycol (esterification-ES clay addition) and bishydroxy ethylene terephthalate (polycondensation-PC clay addition). Thermal, mechanical and barrier properties of these nanocomposites have been studied in comparison to those of neat PET. Differential scanning calorimetry (DSC) results were used to study thermal properties and it was observed that regardless of weight percentage of Na+MMT clay in PET matrices, there were no significant changes in glass transition temperatures (Tg) or melting temperatures (Tm) of the nanocomposites compared to neat PET. It was observed, however, that crystallization rate had increased at higher clay loading because of agglomeration of clay in the PET polymer matrices. For 0.5 wt% ES clay addition PET nanocomposite, tensile strength and tensile modulus observed to be increased by 85% and 92% respective (open full item for complete abstract)

Committee: Saleh Jabarin PhD (Advisor); Maria Coleman PhD (Committee Member); Escobar Isabel PhD (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy in Engineering, University of Toledo, 2007, Chemical Engineering

This research has concentrated on the development of methods for creating exfoliated clay nanocomposites with poly (ethylene terephthalate) (PET) for the purpose of improving barrier and other properties. For this purpose, extrusion blending and in situ polymerization were investigated. The melt extrusion was studied as a function of mobility of PET chain, affinity of clay modifier, and solid state polymerization (SSP). Three IVs of PET (0.48, 0.63, 0.74 dL/g) and three organic clays (Cloisite 10A, 15A, 30B) were melt blended with a twin screw extruder to evaluate variables on the properties. Addition of clay caused big molecular weight reduction after extrusion. Thermal stability experiments showed that the nanocomposites were sensitive to temperature. Fourier Transform Infrared (FTIR), however, indicated hydrolysis was the main reason for molecular weight reduction after extrusion. The SSP rate was decreased and crystallization rate became faster due to clay particles. There were basal spacing increases in PET/Cloisite 10A and PET/Cloisite 30B, but PET/Cloisite 15A did not show any change. After SSP reactions, PET/Cloisite 10A and PET/Cloisite 30B nanocomposites had a new peak at low angle in X-ray diffracton (XRD), indicating more expansion of basal spacing. In situ polymerization was investigated in detail as a function of time and temperature of polymerization, mode of addition of the clay in esterification and in polycondensation, ethylene glycol/terephthalic acid ratio (E/T), diethylene glycol (DEG) suppressor, reactor pressure, antioxidant, and metal stabilizer. There was a limitation to reach 0.60 dL/g IV when the clay was added into the reactor at PET melt polymerization conditions. Foam generation made the melt polymerization of nanocomposites difficult. The concentrations of carboxyl and hydroxyl end groups showed big differences from normal values of PET, due to severe thermal degradation during melt polymerization. This thermal degradation caused drast (open full item for complete abstract)

Committee: Saleh Jabarin (Advisor) Subjects:

Master of Science, Miami University, 2010, Geology and Environmental Earth Science

The reactivity of clay minerals toward technetium immobilization utilizing a suite of clay minerals ranging from smectite-illite including montmorillonite, nontronite, rectorite, mixed layered I-S (70:30), and illite, with chlorite (ripidolite), and palygorskite common in nature. The clay minerals were characterized utilizing multiple techniques. Fe-Oxides were removed prior to bioreduction using a modified dithionite-citrate-bicarbonate method. Fe (II) in the bioreduced clay minerals is used to reduce Tc(VII) to Tc (IV) in PIPES buffer. In the S:I series, the smectite end member was most effective in reducing Tc (VII) and the illite member the least effective, parallel to the extent and rate of Fe(III) bioreduction of these minerals. For all the clay minerals, the ratio of oxidized Fe(II) to reduced Tc(VII) was ~3.5±0.5. These kinetic results are important for our understanding of how various clay minerals may be used to immobilize heavy metal Tc at DOE contaminated sites.

Committee: Hailiang Dong PhD (Advisor); John Rakovan PhD (Committee Member); Mark Krekeler PhD (Committee Member) Subjects: Environmental Geology; Geology; Microbiology; Mineralogy

Doctor of Philosophy, Case Western Reserve University, 1994, Macromolecular Science

In order to utilize the expanding nature of smectite clays in the compensation of shrinkage in epoxy systems, several "epoxyphilic" montmorillonites were prepared via ion exchange reactions. These epoxyphilic montmorillonites contain moieties within their structures that can react with either the epoxide resin, curing agent or both. The swelling behavior of aminolauric acid-intercalated montmorillonite (ALA-MMT) was studied under various swelling conditions prior to curing of the epoxy. It was determined that to obtain larger montmorillonite interlayer distances in the cured epoxy, the ALA-MMT should be swollen in the curing agent rather than the epoxide resin. The curing reaction was shown to increase the interlayer spacing of the ALA-MMT more efficiently when swollen in the curing agent rather than the epoxide resin. Based on these results, models for the swelling behavior of ALA-MMT is proposed. The addition of 2-5% epoxyphilic montmorillonite to epoxy was observed to reduce the maximum residual stress by more than 50%. The glass transition temperatures of these clay/epoxy compounds were generally higher than the pure epoxy. The modulus and ultimate strengths of these compounds were as high or higher than pure epoxy. However, due p rimarily to large agglomerations of montmorillonite particles, the ultimate elongation was drastically reduced.

Committee: Syed Qutubuddin (Advisor) Subjects:

Doctor of Philosophy, University of Akron, 2009, Polymer Engineering

The behavior of polypropylene nanocomposite fibers and films under uniaxial deformation in a partial and fully molten state was investigated. A fiber that exited the die was found to contain orientation gradient in the radial direction that was preserved even after solidification without application of a take up. The shearing effect in the die resulted in a band of oriented outer layers in which broad surfaces of the clay particles became parallel to the surface of the fibers. The polymer phase trapped between these particles exhibited moderate to high preferential orientation levels. Conversely, in the core low levels of preferred orientation were found in both the clay and the polymer phases. Upon application of take up, the presence of clay particles substantially enhanced the orientation of amorphous and crystalline phases in PP/PPgMA (maleic anhydride modified polypropylene) fibers. This was due to the substantial decrease in chain relaxation in the proximity of the clay platelets and enhancement of orientation in the polymer phase in the vicinity of particles that created amplified deformation field by their relative motions. Measurements of the clay orientation in the melt-spun fibers as they undergo “confined melting” in constrained state revealed that these naturally anisotropic nanoplatelets contributed positively to the birefringence of the fibers.A hybrid real-time spectral birefringence technique depolarized light intensity method was used to capture the mechanistic changes that take place during heating, stretching, holding and cooling cycles of PP/PPGMA and nanocomposite films in a partially molten state. During the heating stage, the birefringence and the degree of melting of the as-cast films were determined by real-time depolarizing light intensity technique. The results indicated the initial fraction of crystallites, which govern the deformation behavior of the PP films, remained in dynamic equilibrium with the molten phase prior to the deformatio (open full item for complete abstract)

Committee: Mukerrem Cakmak PhD (Advisor) Subjects: Materials Science; Packaging; Polymers