M.S.

M.S.

This thesis reports on the results of thermal, optical, and spectroscopic studies on poly(vinylidene fluoride)/poly(3-hydroxybutyrate) (PVDF/PHB) blends prepared by melt and solution blending techniques. The blends exhibit - a single, composition dependent Tg. Dynamic crystallization studies indicate that PVDF crystallizes first in all blends containing more than 30% PVDF, and that the blends exhibit single phase behavior in the liquid state. Studies of the melting of isothermally crystallized samples indicate a melting point depression for melt blended PVDF/PHB but no equilibrium melting point depression for the solution blends. Growth rate studies on the α phase of PVDF reveal that its radial growth rate decreases with increasing PHB blend content. Morphological studies demonstrate that the ring spacing of the PVDF α phase increases with increasing temperature and PHB blend content. The different behavior of the meit and solution blends and the previous findings on the thermooxidative degradation behavior of PHB by Kunioka and Doi [1] indicated that PHB may have degraded during the melt blending process. NMR spectra reveal that PHB's chemical composition had not been affected by either blending procedure, but intrinsic viscosity studies indicate a dramatic decrease in PHB's viscosity average molecular weight after melt blending and a smaller decrease after solution blending. FT-IR studies were conducted to determine if PHB did crystallize in the same temperature range as PVDF. FT-IR spectra reveal PHB does crystallize in the same temperature range as PVDF in the solution but not in the meit blends, and the PVDF γ phase content is higher in the solution blends. Finally, TGA studies were performed to determine the effect of PVDF on the degradation of PHB. These findings indicate that PVDF retards the rate of PHB degradation in both types of blends. / Master of Science

Lyotropic and thermotropic high strength liquid crystalline polymers have become an important area of research and development in polymeric, high performance materials. These materials have afforded excellent high temperature stability and high strength in the oriented direction, but not in the transverse direction. Hence, "balancing" the properties in both directions is an important area of research. Segmented polymers composed of an amorphous, glassy engineering thermoplastic, and an anisotropic, liquid crystalline polymer were synthesized and investigated. The isotropic phase is based upon a ductile poly(arylene ether sulfone), while the anisotropic segment is based on a rigid poly(arylate) moiety. The difunctionally terminated, controlled molecular weight poly(sulfone) oligomers were synthesized via a nucleophilic aromatic substitution reaction. Functional end groups included phenolic, acetate and carboxyl. The structure and reactivity of these oligomers was characterized by analytical techniques, including FT-IR, NMR, and polymer physical characterization methods such as, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and thermal mechanical analysis (TMA), and dynamic mechanical thermal analysis (DMTA). The well characterized, difunctionally terminated poly(sulfone) oligomers were then utilized along with ester forming monomers in a subsequent melt acidolysis reaction to form segmented poly(sulfone)-poly(arylate) co- or terpolymers. Earlier work by Lambert (281-283) showed that solution and interfacial techniques could only be utilized to synthesize segmented polymers with low poly(arylate) contents. The melt acidolysis technique allowed the synthesis of poly(sulfone)- poly(arylate) polymers with poly(arylate) contents as high as 90 weight percent. Along with a high degree of agitation, the melt acidolysis technique utilized chlorobenzene as a solvent in the initial stage of the reaction to enhance the mixing of the poly(sulfone) oligomers and ester forming monomers, allowing true segmented polymers to be formed. This was proven by FT-IR and extraction studies, which determined that very little of the original poly(sulfone) oligomer was extracted by refluxing chloroform. The morphology of these polymers was studied by polarized optical microscopy, and wide angle X-ray scattering. Low weight fraction poly(arylate) co- and terpolymers were determined to be amorphous, while higher poly(arylate) weight fraction polymers (15 weight percent or greater) were found to be semi-crystalline or liquid crystalline. Thermal analysis (DSC) also gave evidence that these materials were semi-crystalline or liquid crystalline. Also, as the weight fraction of poly(arylate) was increased, a significant improvement in solvent resistance was observed as well as an improvement in the modulus and tensile strength. / Ph. D.

Problems related to estimating soil ingestion by wildlife species from analysis of feces were examined. Soil ingestion was investigated as a means by which wildlife may be exposed to environmental contaminants, particularly Pb. Titanium (Ti) and acid-insoluble residue (AIR) tracer methods for estimating soil ingestion were compared. The two methods were not significantly (P > 0.05) different when diet consisted of 10% (dry weight, d.w.) soil. When diet contained 5% soil, soil ingestion was more accurately estimated using the Ti method. Digestibility of soil can be ignored in the equation for quantifying soil ingestion from analysis of feces. Soil ingestion, as percentage dry matter intake (% DMI), by five wildlife species was estimated from analysis of feces or intestinal contents using the Ti tracer method. Soil ingestion by mourning doves (Zenaida macroura) was estimated using AIR analysis of crop contents. Mean (± S.E.) soil ingestion by Canada geese (Branta canadensis) and mallards (Anas platyrhynchos) were 4.92 (± 0.60) and 11.73 (± 1.54), respectively. Diets of short-tailed shrews (Blarina brevicauda) consisted of 5.20 (± 1.87)% soil, white-footed mice (Peromyscus leucopus) 16.21 (± 4.85)%, meadow voles (Microtus pennsylvanicus) 2.01 (± 0.34)%, and mourning doves 0.83 (± 0.41)% soil. Mallards collected from Killarney Lake, northern Idaho were analyzed for free erythrocyte protoporphyrin, fecal, liver, and kidney Pb concentrations, and soil/sediment ingestion. Sediment from the area contained 4485 ppm Pb (d.w.). Protoporphyrin was a poor indicator of Pb contamination at this level of exposure and/or under these conditions. Soil/sediment ingestion by mallards averaged 7.5% DMI. Tissue Pb concentrations indicated mallards were suffering from chronic exposure to low concentrations of Pb. Sediment collected from Killarney Lake (4485 ppm Pb) was fed to northern bobwhites (Colinus virginianus) at 8% DMI for 21 dad. Lead concentrations in blood, liver, and kidneys were determined and compared to control values. Treated and control birds showed no significant decline (P > 0.05) in feed intake and body mass did not change by greater than ± 1% over time. Lead in treated birds averaged 7 ppm (d.w.) in liver, 30 ppm (d.w.) in kidneys, and 126 ppb (wet weight, w.w.) in blood. Liver and kidney Pb concentrations of controls were < 0.1 ppm (d.w.) and averaged 630 ppm (w.w.) in blood. / Master of Science

Present stress analysis of adhesively bonded joints suffers from inadequate adhesive material characterization. The lack of correlation between bulk adhesive properties and the corresponding in-situ behavior has led to numerous adhesive test geometries. The current study was an attempt to predict the nonlinear viscoelastic response of an adhesive in-situ using properties obtained from a pure shear test geometry. Four candidate adhesive test geometries were studied both analytically and experimentally in terms of accurate shear property determination and realistic adhesive bond simulation. The thick adherend joint was chosen as the experimental reference of actual viscoelastic response in-situ; the Arcan specimen provided a pure shear stress state for material viscoelastic characterization. Results of finite element analysis and extensive experimental evidence suggest that residual thermal stresses alter the in-situ adhesive properties compared to the bulk adhesive: Furthermore, preliminary results indicate that the free volume nonlinear viscoelastic theory accounts for the effect of residual strains on the in-situ adhesive mechanical response. / M.S.

A new approach to the investigation of the optical properties of polytypic minerals that combines spindle stage techniques, X-ray diffraction methods, electron microprobe analysis, and dielectric tensor calculations has been developed and applied to zinc sulfides and chloritoids. For the first time, X—ray diffraction studies of natural anisotropic zinc sulfides have documented the simultaneous occurrence of twinning and stacking disorder along more than one of the four symmetry equivalent <111> directions of sphalerite. Precession photographs of optically anisotropic zinc sulfides are characterized by twin—equivalent diffraction maxima and diffuse diffraction streaking along lattice rows with (h-k) ≠ 3n (equivalent hexagonal indices) in one or two <111> directions. A system of linear equations has been used to calculate the approximate volume fractions of each twin domain and the sphalerite host domain. Dielectric tensor calculations have been performed to illustrate that mixtures of cubic and hexagonal zinc sulfide may be optically biaxial if the intergrowth occurs along more than one of the symmetry equivalent <111> directions of sphalerite (cubic). The dependence of the optical properties upon the chemical variation and polytypic intergrowth in the Hg-Fe chloritoids has been investigated. The effects of the variation in chemical composition of specific polytypic compositions were analyzed first. The refractive indices of 10 approximately pure 2M₂ Hg-Fe chloritoids show strong correlations (R² ≥ 0.094) to the proportion of Hg cations in the H(1B) site, Hg/(Hg + Fe + Hn) - HGN. Correlations between the optical orientation angles and HGN were weaker (R² ≤ 0.87). The optical orientation is very sensitive to small variations in the polytypic composition, especially orientation angles that have fixed values in 2M₂ chloritoid. The parameter showing the most sensitivity is ∠ X ⋀ b, which is 0° in an ideal 2M₂ chloritoid, but increases to about 6° for a chloritoid containing 10% by volume 1Tc polytype. The sum of ∠ Y ⋀ c* and ∠ Z ⋀ c* for an ideal 2M₂ chloritoid has a value of 90°, whereas a chloritoid with 10% 1Tc has a sum of 92°. Although not as sensitive as ∠ X ⋀ b, this parameter can be determined with only a spindle stage or universal stage. The observed dependence of the optical properties on polytypic intergrowth and chemical variation has been modeled using dielectric tensor calculations based on the properties of a 1Tc layer and assuming that the 2M₂ polytype is derived by twinning the 1Tc polytype about [010] with an (001) composition plane. / Ph. D.

Transition metal compounds such as Co₂(CO)₈ have often been used to catalyze various organic reactions. Severe difficulties may be encountered when attempts are made to recover and separate the soluble catalysts. A heterogeneous system consisting of Co₂(CO)₈ impregnated on zeolites with faujasitic structure has been designed and investigated using a variety of techniques. In situ FTIR spectroscopy and carbon monoxide evolution were used to identify the major products generated, namely Co₄(CO)₁₂ and Co(CO)_4^-. Disproportionation may be induced thus forming Co(CO)_4^- and an associated cation from the supported subcarbonyls by addition of various ligands such as methanol. The location of the supported cobalt carbonyls is determined by their reactivity toward various phosphines with various kinetic diameters. The materials prepared in this manner were found to be active in catalyzing the methanol carbonylation reaction and following thermolysis were also found to be active Fischer-Tropsch catalysts. Major products observed in the carbonylation of methanol were methyl acetate and an acetaldehyde dimethyl acetal. The supported cobalt catalyst displays greater activity than Co₂(CO)₈ in solution for the carbonylation reaction when conducted under similar conditions. In the Fischer-Tropsch process, selectivity is seen for the production of linear, short-chain hydrocarbons. / Ph. D.

This study investigated several facets of the environmental coping process. Environmental coping was defined as any behavioral or cognitive attempt to reduce annoyance resulting from bothersome environmental conditions. In this study, library patrons using study carrels were observed while two people talked nearby. The library patron's behaviors in response to this event were recorded. In addition, self-report data were collected by means of follow-up questionnaires. Drawing on the literature from areas of research such as environmental stress, the coping process, and the effects of perceived control, four hypotheses were proposed. In summary, these hypotheses proposed that people would attempt to deal with the intrusion created by others talking nearby through indirect means first, and that people would attempt to"make do" (satisfice) rather than exert control over environmental events (optimize). Due to methodological difficulties, no definite conclusions could be drawn. Suggestions for methodological refinement in this area of research were offered and conceptual issues discussed. / M.S.

Recent advances in VLSI technology have stimulated research efforts in the area of highly reliable fault tolerant, general purpose computing systems, notably, parallel systems. An automatically reconfigurable, fault-tolerant, parallel architecture is suited to VLSI technology. The architecture, a uniformly interconnected array of identical cells, is capable of functional reconfiguration as well as fault reconfiguration. Microprocessor cells are suggested as the "fabric" for implementation of the array. This thesis also introduces an I/O algorithm as an extension to the reconfiguration process, and outlines the steps by which the array cells construct paths from the active-array to the cellular array I/O ports. Path reconfiguration is presented as the method by which fault-free paths replace faulty paths. A testing algorithm is described for use in the self-testing operation of the array. The types of tests that are conducted on cells are outlined, and the basis by which a cell determines the faulty or fault-free status of a cell is described. / M.S.