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Polymer additives exemplify many classes of compounds which possess a wide variety of chemical (i.e., phenols, amides, esters) and physical (i.e., volatility, solubility) properties. They are incorporated into polyolefins and other such polymeric materials for a number reasons: (a) to prevent degradation by ultraviolet light, heat, and oxygen; (b) to aid in the processing of the polymer; and (c) to modify the physical properties of the polymer. Since the purity and amount of additive can affect polymer properties, it is very important to characterize and quantify additives in polymer products. Traditional liquid solvent/polymer extraction methods, which involve dissolution/precipitation, are time-consuming, uneconomical, and the recoveries are significantly lower than 90%. In recent years, analysis with supercritical fluids (SFs) has emerged as an alternative analytical technique because SFs afford higher diffusivity and lower viscosity. In this research, an on-line Supercritical Fluid Extraction (SFE)/Supercritical Fluid Chromatography (SFC) system was assembled to provide efficient extraction and separation of polymer additives with quantitative results. The effects of various SFE/SFC parameters, such as trapping temperature, injection temperature, extraction pressure and temperature, dynamic extraction time, and fluid flow rate on extraction and separation efficiencies of different additive standards (i.e., BHT, BHEB, Isonox 129, Irganox 1076 and Irganox 1010) were investigated. Optimized conditions were employed to quantitatively extract additives from LDPE. Identification of additives was performed by comparing the retention time with each additive standard. Results obtained from on-line SFE/SFC were compared to results from off-line SFE/High Performance Liquid Chromatography (HPLC) and off-line Enhanced Solvent Extraction (ESE)/HPLC. / Master of Science

This research is directed to the characterization of the thermodynamic properties and viscosity of lubricant base oils modified with polymeric additives. Several groups of mineral and synthetic base oils, including Ultra S4, Ultra S8, and poly alpha olefin PAO 4 have been studied. Among the various types of additives explored were viscosity index modifiers, polyisobutylene polymers (PIBs), and dispersants. The viscosity index modifiers are studied in terms of different polymer architectures, molecular weights, presence or absence of functional groups, and their concentrations. The dispersants are studied in terms of concentration, molecular weight, and presence of capping groups. Density data, as the basic thermodynamic data, are generated using a high-pressure variable-volume view-cell over a pressure range from 10 to 40 MPa and a range of temperatures from 298 to 398 K. The density data are then correlated with the Sanchez-Lacombe equation of state, from which key thermodynamic properties, namely isothermal compressibility, isobaric expansivity, and internal pressure are derived. These properties offer a rational approach to better understand molecular packing in lubricants under high pressure and temperature conditions which has direct impact on film formation. Viscosity determinations are carried out using a custom-designed high-pressure rotational viscometer. Data were generated in the pressure range from 10 to 40 MPa, but at temperatures ranging from 298 to 373 K as a function of shear rate up to 1270 s-1. Viscosity data were then correlated with density which provides interpretations in terms of free-volume and density scaling models. The molecular parameters produced from these correlations support the interpretation of molecular packing under high pressure and temperature conditions. The results of this study included several key findings. With regards to density, the addition of viscosity index modifiers to Ultra S4 base oil caused the density to increase, except for the addition of functionalized olefin copolymers (OCPs) which caused the density to decrease. This was true with both high and low molecular weight additives. In the case of Ultra S8 base oil, the addition of OCPs generally decreased the density, while the addition of polymethacrylates (PMAs) caused the density to increase. In terms of compressibility and expansivity, the addition of high molecular weight viscosity index modifiers to Ultra S4 base oil generally decreased both these properties. However, the compressibility increased with the addition of 5 wt % functionalized PMA and 2 wt % star styrene butadiene (SSB). Furthermore, there was less of a decrease in compressibility with the addition of functionalized additives. With the addition of low molecular weight viscosity index modifiers to Ultra S4 base oil, little change was observed in compressibility, and the expansivity decreased to a lesser degree than with the addition of high molecular weight viscosity index modifiers. Viscosity index modifiers did not alter the compressibility of Ultra S8 base oil. Compared to Ultra S4, expansivity in Ultra S8 decreased to a lesser extent. The internal pressure was observed to be lowered to a greater degree in either Ultra S4 or Ultra S8 base oil with the addition of additives with more rigid internal structures (PMA and SSB). The decrease occurred to a greater degree with the addition of the higher molecular weight versions of additives studied and/or with the incorporation of functional groups to the additives. Although density changes were often greater with the addition of additives to the Ultra S8 base oil, all other derived thermodynamic properties, including internal pressure, changed to a greater degree with the addition of additives to the lower molecular weight Ultra S4 base oil. The viscosity generally increased to varying degrees with the addition of different additives to either base oil. The addition of functionality and higher molecular weight additives led to more consistent viscosity increases at higher temperatures. At the highest viscosity isotherm tested, 373 K, the addition of viscosity index modifiers resulted in similar viscosity values in either base oil, even though the viscosity of Ultra S4 at 373 K is much lower than the viscosity of Ultra S8 at this temperature. However, at 298 K, the viscosity index modifiers increased the viscosity of the Ultra S8 base oil to much higher values than the viscosity of the Ultra S4 base oil. Model based correlations of viscosity showed that with addition of high molecular weight viscosity index modifiers to Ultra S4 base oil, the parameters that are linked to free-volume overlap and the density dependence were more sensitive to the addition of OCPs than with the addition of PMAs and SSBs. These changes were reflected in larger free-volume overlap parameters and larger density exponent values. However, with a low molecular weight addition, the resulting parameters changed more with the addition of PMAs than OCPs. Overall, the addition of polymers with more rigid architecture led to more similar changes in correlative parameters across molecular weights from that of the original base oil, while for the OCP addition, the molecular weight had more of an influence on the degree of change. With addition of viscosity index modifiers to the Ultra S8 base oil, the architecture of the additive had more of an influence on the viscosity correlation parameters as the addition of PMA led to more noticeable changes in the parameters (resulting in lower free-volume overlap parameters, and a lower density exponent) than the addition of OCP, irrespective of the molecular weight or functionality. In either base oil, the addition of PMA led to lower free-volume overlap parameters and density exponent values than the addition of OCP. In this study it was observed that the addition of functionality, or polar groups to viscosity index modifiers, led to more desirable thermodynamic and rheological property changes to the lubrication base oil. This change was more definitive with the addition of polymers with more rigid architecture, such as PMAs and SSBs in contrast to the OCPs. The study on the addition of PIBs and capped or uncapped dispersants showed little variation in the resulting density and viscosity values when added to Ultra S4 base oil. However, the compressibility in these systems generally increased while the expansivity decreased except with the addition of PIBs. The internal pressure decreased to similar levels for all additive additions, except for the lowest molecular weight PIB, in which there was little change. The study on the addition of PIBs to different base oils showed that low molecular weight PIBs had the potential to disrupt the packing of a more uniform PAO 4 base oil and change the thermodynamic properties and correlation parameters to a greater degree than with the addition of higher molecular weight PIBs. This resulted in higher compressibility and internal pressure values with the addition of low molecular weight PIB compared to the higher molecular weight PIBs. However, there was little variation in viscosity with any of the PIB additions, except for the highest molecular weight PIB. / Doctor of Philosophy / Several legislations have recently been passed which are aimed at improving the fuel efficiency in cars. One way to improve fuel efficiency is to reduce friction through improvements on the lubrication systems such as engine oils and transmission fluids. This applies to lubricants operating under cold start conditions and up to operating condition of approximately 100ºC. Additionally, the lubricants are subject to extreme pressure conditions when they are squeezed between contacts such as gears or clutch plates. Therefore, it is crucial to explore lubricant performance under high pressure and temperature conditions. The lubricants that are preferred are those that form a layer that completely protects metal contacts without causing the contacts difficulty in moving, causing a loss in efficiency. The desired film layer thickness under high pressure and temperature conditions can be improved using different additives. This thesis explores high pressure and temperature behavior of lubricant systems modified with different types of additives using uniquely designed lab instrumentation. The focus is on understanding their volumetric and flow properties, which directly influence the film layer and effectiveness of the lubricant. Volumetric properties are characterized by measurement of density as a function of temperature and pressure. Density data provides insights on molecular packing in lubricant systems. Flow properties, specifically, resistance to flow, can help analyze a potential loss in efficiency caused by the lubricant systems. The thesis is thus a comprehensive study on the volumetric and flow properties of lubricants at a wide range of temperatures ( from 298 to 398 K) and pressures (from 10 to 40 MPa) and how these properties are affected in the presence of additives that aim to improve lubricant performance.

The extraction of fifteen (15) polymer additives with supercritical carbon dioxide which are used as antioxidants, uv stabilizers, process lubes, flame retardants and antistats from eight formulations of polystyrene is demonstrated and compared to traditional dissolution/precipitation extractions. The purpose of the study was twofold: 1) the development of a high performance liquid chromatography (HPLC) method(s) for the additives and 2) the determination of the viability of supercritical fluid extraction (SFE) for the additives from polystyrene. Separation of some of the additives was achieved using reversed phase liquid chromatography. Nine of the additives were assayed in this manner while, the remaining six additives could not be assayed using reversed phase liquid chromatography. In order to develop an extraction method for the additives, the effects of static extraction time, CO2 density, and temperature were first investigated. These preliminary extractions revealed that a static extraction period which afforded an opportunity for the polymer to swell combined with a high CO2 density and extraction temperature above the glass transition (Tg) yielded quantitative recoveries of the additives. Triplicate extractions of the various polystyrene formulations matched additive recoveries obtained by the traditional dissolution/precipitation method. / Master of Science

Drilled shaft construction often requires the use of drill slurry to maintain borehole stability during excavation and concreting. While drill slurry may be composed of fluids ranging from air to petroleum, drilled shaft construction typically makes use of water based drilling fluids. Although clean water may be utilized as a drilling fluid, a premixed slurry consisting of water, minerals, and/or polymers is more commonly used. Florida Department of Transportation (FDOT) specifications require the use of mineral slurry for all primary structures. The slurry resists the intrusion of groundwater, slows the outward migration of drilling fluid from the excavation, and aids in the removal of suspended soil cuttings. The mechanisms by which mineral slurries work are quite different from those of polymer slurries. Due to these differences, it is unclear whether a mineral based slurry, which has been fortified with polymers by manufacturers or enhanced through the addition of polymers in the field, behaves more like a mineral slurry rather than polymer slurry. This thesis provides an overview of the methods used to measure physical slurry parameters of interest. These parameters include density, viscosity, pH, sand content, and filtration control. Methods employed to describe the slurry parameters include tools and instrumentation commonly used in both field and laboratory settings.

Made available in DSpace on 2014-12-17T14:07:02Z (GMT). No. of bitstreams: 1 JoseKMAR_DISSERT.pdf: 2948541 bytes, checksum: 646d8653b036843236db0bfc42c7f90b (MD5) Previous issue date: 2012-02-10 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Currently new polymeric materials have been developed to replace other of traditionally materials classes. The use of dyes allows to expand and to diversify the applications in the polymeric materials development. In this work the behavior and ability of azo dyes Disperse Blue 79 (DB79) and Disperse Red 73 (DR73) on poly(methyl methacrylate) (PMMA) were studied. Two types of mixtures were used in the production of masterbatches: 1) rheometer 2) solution. Processing by extrusion-blow molding of PMMA was carried out in order to evaluate the applications of polymeric films. Thermal analysis were performed by thermogravimetry to evaluate polymer and azo dyes thermal stability. Colorimetric analysis were obtained through monitoring the spectral variations associated with sys/trans/anti azo dyes isomerization process Colorimetric data were treated and evaluated in accordance to the color system RGB and CIEL*ab, by monitoring the color change as function of time. Mechanical properties, characterized by tensile tests, were evaluated and correlated with the presence and content of azo dyes in the samples. Analyses by scanning electronic microscopy (SEM) were performed on the surfaces of samples to check the azo dye dispersion after the mixing process. It was concluded that the production of PMMA/azo dyes is possible and feasible, and the mixtures produced had synergy of properties for use in various applications / Atualmente novos materiais polim?ricos v?m sendo desenvolvidos, visando substituir outras classes de materiais tradicionalmente empregados. O uso de corantes possibilita ampliar e diversificar as possibilidades de aplica??es no desenvolvimento desses novos materiais. Neste trabalho foi estudado o comportamento e a capacidade de tingimento dos azocorantes: Azul Disperso 79 (DB79) e o Vermelho Disperso 73 (DR73), em uma matriz de poli(metacrilato de metila) (PMMA). Duas formas de misturas foram utilizadas na produ??o dos concentrados: na primeira, em re?metro de torque e na segunda, em solu??o. O processamento por extrus?o-sopro do PMMA foi realizado neste trabalho com intuito de avaliar suas aplica??es na forma de filmes polim?ricos. An?lises t?rmicas foram realizadas por termogravimetria para avaliar a estabilidade t?rmica dos pol?meros e dos azocorantes. An?lises por colorimetria foram obtidas por meio do acompanhamento das mudan?as espectrais associadas ao processo de isomeriza??o cis/trans/anti dos azocorantes. Os dados de colorimetria foram tratados e avaliados segundo o sistema de cores RGB e CIEL*ab, por meio do acompanhamento da mudan?a de colora??o em fun??o do tempo. As propriedades mec?nicas, caracterizadas por meio de ensaios de tra??o uniaxial, foram avaliadas e correlacionadas com a presen?a e quantidade de azocorantes na constitui??o das amostras. An?lises por microscopia eletr?nica de varredura (MEV) foram realizadas nas superf?cies das amostras para verificar a dispers?o dos corantes no final do processo de mistura. Verificou-se que a produ??o de PMMA/azocorantes ? poss?vel e vi?vel e as misturas produzidas apresentaram sinergia de propriedades para utiliza??o em diversas aplica??es

In this thesis we study a variety of problems in fluid turbulence, principally in two dimensions. A summary of the main results of our studies is given below; we indicate the Chapters in which we present these. In Chapter 1, we provide an overview of several problems in turbulence with special emphasis on background material for the problems we study in this thesis. In particular, we give (a) natural and laboratory examples of fluid turbulence, (b) and introductory accounts of the equations of hydrodynamics, without and with polymer additives, Eulerian and Lagrangian frameworks, and the equations of motion of inertial particles in fluid flows. We end with a summary of the problems we study in subsequent Chapters of this thesis. In Chapter 2, we carry out the most extensive and high-resolution direct numerical simulation, attempted so far, of homogeneous, isotropic turbulence in two-dimensional fluid films with air-drag-induced friction and with polymer additives. Our study reveals that the polymers (a) reduce the total fluid energy, enstrophy, and palinstrophy, (b) modify the fluid energy spectrum both in inverse- and forward-cascade regimes, (c) reduce small-scale intermittency, (d) suppress regions of large vorticity and strain rate, and (e) stretch in strain-dominated regions. We compare our results with earlier experimental studies and propose new experiments. In Chapter 3, we perform a direct numerical simulation (DNS) of the forced, incompressible two-dimensional Navier-Stokes equation coupled with the FENE-P equations for the polymer- conformation tensor. The forcing is such that, without polymers and at low Reynolds numbers Re, the lm attains a steady state that is a square lattice of vortices and anti-vortices. We nd that, as we increase the Weissenberg number (Wi), this lattice undergoes a series of nonequilibrium phase transitions, first to spatially distorted, but temporally steady, crystals and then to a sequence of crystals that oscillate in time, periodically, at low Wi, and quasiperiodically, for slightly larger Wi. Finally, the system becomes disordered and displays spatiotepmoral chaos and elastic turbulence. We then obtain the nonequilibrium phase diagram for this system, in the Wi − Re plane, and show that (a) the boundary between the crystalline and turbulent phases has a complicated, fractal-type character and (b) the Okubo-Weiss parameter provides us with a natural measure for characterizing the phases and transitions in this diagram. In Chapter 4, our study is devoted to heavy, inertial particles in two-dimensional (2D) tur- bulent, but statistically steady, flows that are homogeneous and isotropic. The inertial particles are distributed uniformly in our simulation domain when St = 0; they start to cluster as St increases; this clustering tendency reaches a maximum at St 1 and decreases thereafter. We then obtain PDFs of and show that their left tails, which come from extensional regions, do not depend sensitively on St; in contrast, their right tails, from the vortical regions of the flow, are consistent with the exponential form ∼ exp ‰− + Ž; and we nd that the scale + decreases with St until St _0:1 and then saturates at a value _0:75. Our persistence-type studies yield the following results, when we consider forcing that leads to an energy spectrum that is dominated by a forward-cascade regime: In strain-dominated or extensional regions of the flow, wend that the cumulative PDF of the persistence time decays exponentially; this decay yields a time scale T−, which increases rapidly with St, at low values of St, but more slowly after St _0:75. By contrast, in vortical regions of the flow, this cumulative PDF displays a tail that has power-law and exponential parts; the power-law part yields the persistence exponent _ and the exponential tail gives a time scale T−; _ increases with St, whereas T− decreases with St; _ and T− reach saturation values as St increases. From the cumulative PDF of the particle mean-square displacement r2, we obtain the time scale Ttrans at which there is a crossover from ballistic to diffusive behavior; we _nd that Ttrans increases with St. The PDFs of v2, the square of the particle velocity, and v2 ejected, the square of the velocity of a particle just as it is ejected from a region with _ > 0 (vortical region) to one that has _ < 0 (extensional region), do not show a significant dependence on St; the tails of these PDFs are characterized by power-law decays with exponents _1 and _5~3, respectively. Our next set of results deal with statistical properties of special combinations of the acceleration a =dv~dt and the velocity v. For instance, the curvature of the trajectory is _ =aÙ~v2, where the subscript Ù denotes the component perpendicular to the particle trajectory; we obtain PDFs of _ and _nd there from that particles in regions of elongational flow have, on average, trajectories with a lower curvature than particles in vortical regions; this . We also determine how the number of number of points NI , at which a ×v changes sign along a particle trajectory, as time increases; we _nd that the increase of NI with time and decrease as St increases. Our ninth set of results show that the characteristic decay time T_ for decreases with St. In Chapter 5, we study the statistical properties of orientation and rotation dynamics of elliptical tracer particles in two-dimensional, homogeneous and isotropic turbulence by direct numerical simulations. We consider both the cases in which the turbulent flow is generated by forcing at large and intermediate length scales. We show that the two cases are qualitatively different. For the large-scale forcing, the spatial distribution of particle orientations forms large- scale structures, which are absent for the intermediate-scale forcing. The alignment with the local directions of the flow is much weaker in the latter case than in the former. For the intermediate- scale forcing, the statistics of rotation rates depends weakly on the Reynolds number and on the aspect ratio of particles. In contrast with what is observed in three-dimensional turbulence, in two dimensions the mean-square rotation rate decreases as the aspect ratio increases. In Chapter 6, we study the issue of intermittency in numerical solutions of the 3D Navier-Stokes equations on a periodic box [0; L]3. This is addressed through four sets of numerical simulations that calculate a new set of variables defined by Dm(t) = where All four simulations unexpectedly show that the Dm are ordered for m =1 ….,9 such that Dm+1 <Dm. Moreover, the Dm squeeze together such that Dm+1/Dm 1 as m increases. The values of D1 lie far above the values of the rest of the Dm, giving rise to a suggestion that a depletion of nonlinearity is occuring which could be the cause of Navier{Stokes regularity. The first simulation, by R. Kerr, is of very anisotropic decaying turbulence ; the second and third, which have been carried out by me, are of decaying isotropic turbulence from random initial conditions and forced isotropic turbulence at fixed Grashof number, respectively ; the fourth, by D. Donzis, is of very-high-Reynolds-number forced, stationary, isotropic turbulence at resolutions up to 40963 collocation points. For the sake of completeness and for a comparison of the data from all these four simulations, all the results are presented; however, in the Sections that deal with the simulations, I indicate who carried out the calculations reported there. I also present an extension of this work to two-dimensional fluid turbulence; this has not been submitted for publication so far. We hope our in silico studies of 2D and 3D turbulence will stimulate new experimental, numerical, and theoretical studies.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-28T21:49:04Z No. of bitstreams: 1 KARINE CASTRO NÓBREGA – DISSERTAÇÃO (UAEMa) 2015.pdf: 1849613 bytes, checksum: c5a145f0dd677d54aab0ed55f6ccc4e9 (MD5) / Made available in DSpace on 2018-06-28T21:49:04Z (GMT). No. of bitstreams: 1 KARINE CASTRO NÓBREGA – DISSERTAÇÃO (UAEMa) 2015.pdf: 1849613 bytes, checksum: c5a145f0dd677d54aab0ed55f6ccc4e9 (MD5) Previous issue date: 2015-02-23 / CNPq / A perfuração de poços de petróleo pode danificar fortemente a formação, incluindo a região de interesse: o reservatório. Perfurar sem que se danifique o reservatório caracteriza-se como um grande desafio, e por isso, tem sido estimulado o desenvolvimento de tecnologias de fluidos e otimização de processos de perfuração, incluindo, por exemplo, o uso de fluidos argilosos com vistas à minimização de perdas excessivas de filtrado para as formações permeáveis. Desta forma, este trabalho teve como objetivo avaliar a influência dos aditivos carboximetilcelulose (CMC) e calcita (CaCO3) e suas interações nas propriedades de filtração de fluidos de perfuração argilosos. Para tanto, foi utilizada uma amostra de argila bentonítica, comercialmente conhecida por Volclay, duas amostras de CMC com diferentes massas molares (CMC 1 (9,0 x 104g/mol) e CMC 2 (2,5 x 105g/mol)) e mesmo grau de substituição (DS = 0,7) e, duas amostras de calcita (CaCO3), com diferentes diâmetros médios de partículas e curvas de distribuição em tamanho. Foram realizadas a caracterização física e mineralógica da amostra de argila e a caracterização granulométrica das amostras de calcita, em seguida determinadas as propriedades reológicas (viscosidades aparente (VA) e plástica (VP), limite de escoamento (LE) e força gel (FG)) e de filtração (volume de filtrado (VF), volume de filtrado corrigido (VFcorr), spurt loss (SPL), espessura (h) e permeabilidade (k) do reboco e poder de retenção (R)) dos fluidos argilosos estudados. Os resultados evidenciaram que os fluidos estudados apresentaram comportamento pseudoplástico e os fluidos argilosos preparados com elevada concentração de CMC 2 (2g/350mL de água) apresentaram melhores valores de propriedades reológicas, pois estas propriedades são fortemente influenciadas pelo grau médio de polimerização dos aditivos poliméricos. A aditivação de fluidos argilosos com carboximetilcelulose de baixa massa molar e com calcita de granulometria fina conferiu aos fluidos melhor desempenho na melhoria das propriedades de filtração. Isto aconteceu, porque no meio aquoso a CMC 1 em elevada concentração associada a calcita 1 conduziu a menores valores de VF, h e k e, elevados valores de R. / The drilling of oil wells can greatly damage the formation, including the region of interest: the reservoir. Drilling without damaging the reservoir is characterized as a big challenge, and therefore, has been stimulated the development of fluid technologies and optimization of drilling processes, including, for example, the clay fluids use aiming at minimization excessive losses of the filtrate into the permeable formations. Thus, this study aimed to evaluate the influence of additives carboxymethylcellulose (CMC) and calcite (CaCO3) and their interactions in the filtration properties of clay drilling fluids. For this, it was used a sample of bentonite clay, commercially known by Volclay, two samples of CMC with different molecular weight (CMC 1 (9,0 x 104g/mol) and CMC 2 (2,5 x 105g/mol) ) and the same degree of substitution (DS = 0,7) and two samples of calcite (CaCO3) with different average diameters of particles and size distribution curves. It was done the physical and mineralogical characterization of the clay sample and the particle size characterization of the calcite samples it was also determined the rheological properties (apparent viscosity (AV) and plastic (PV), yield limit (YL) and gel strength (GS)) and of filtration (filtrate volume (FV), filtrate volume corrected (FVcorr), spurt loss (SPL), cake thickness (h) and permeability (k) and retaining power (R)) of the studied clay fluids. The results showed that the studied fluids showed pseudoplastic behavior and clay fluids prepared with high concentration of CMC 2 (2g/350mL of water) showed better values of rheological properties, because these properties are strongly influenced by the average degree of polymerization of polymeric additives. The additived clay fluids with low molecular weight carboxymethylcellulose and with fine granulometry calcite gave the fluids best performance in improving the filtration properties. This happened because in the aqueous medium the CMC 1 in high concentration associated at calcite 1 led at lower values of FV, h and k and high values of R.