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Orientador: Edvaldo Sabadini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T13:40:57Z (GMT). No. of bitstreams: 1 Sant'AnnaJunior_Walcyr_M.pdf: 635340 bytes, checksum: 1249edac738f7933eee08fdecb6d0d7f (MD5) Previous issue date: 2001 / Resumo: Este trabalho envolve o estudo do equilíbrio de fase líquido-líquido apresentado pelo sistema poli(etileno glicol), (PEG) e hidrocarbonetos aromáticos (HA). Os diagramas de fase são do tipo UCST (upper critical solution temperature), sendo que o grau de miscibilidade é fortemente dependente da massa molar do PEG e do número de CH2 presentes na cadeia alifática das moléculas dos HA. Também são mostrados estudos realizados com os isômeros o, m, e p-xileno e n e iso-propil benzeno, permitindo, nestes casos, verificar a influência da posição do substituinte e da estrutura da cadeia alifática na miscibilidade deste sistema. Os diagramas foram obtidos a partir de medidas visuais de turbidez (ponto de névoa) para as diferentes soluções poliméricas. Neste trabalho procuramos discutir os aspectos entálpicos e entrópicos que levam à separação de fases. O modelo de Flory-Huggins para soluções poliméricas foi utilizado para determinar os parâmetros de interação PEG- HA / Abstract: This work is concerned with the liquid-liquid phase equilibrium shown by a system composed of poly(ethylene glycol) [PEG] and aromatic hydrocarbons [AH]. The diagrams were obtained by cloud point titration. Studies were carried out using o, m, p-xylene isomers and normal and iso-propyl benzene isomers, in order to verify the influence of the substituent position and of the aliphatic chain structure on the miscibility of the system. The phase diagrams obtained are of the UCST (upper critical solution temperature) class. The miscibility is strongly dependent on PEG molar weight and on the number of CH2 units of the aliphatic chain. The Flory-Huggins model for polymeric solutions was employed to determine the PEG-AH interaction parameters. The enthalpic and entropic contribution which lead to phase separation are discussed / Mestrado / Físico-Química / Mestre em Química

In this study, the nanocomposite of graphene and PMMA at the different volume fractions was investigated by molecular dynamics and dissipative particle dynamics simulations. The MD simulation can be performed to simulate the nanocomposite system at different weight fractions to obtain the different repulsive parameters. After obtaining the repulsive parameters, the DPD simulation can be utilized to study the equilibrium phase of graphene and PMMA nanocomposite. From our result, all equilibrium phases at different volume fractions are cluster. However, it is difficult to enhance the property for nanocomposite material due to the aggregated graphene (cluster). Hence, we change the interaction repulsive parameters to stand for the different degrees of functionalized graphene. When the interaction repulsive parameter is smaller than 80, the equilibrium phase is dispersion. In addition, the different number of functionalized garphene bead per graphene was studied, and results show that the equilibrium phase is dispersion when all graphene beads per graphene are functionalized.

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Most crude oils contain traces of vanadyl porphyrins within their asphaltene fraction. Although these metals are only present in trace quantities, they have a significant detrimental impact on crude oil processing units; therefore, their selective removal is highly desirable. The current work studied the interaction of these vanadyl porphyrins with asphaltenes using two approaches: 1) equilibrium solubility measurements of model porphyrins and 2) membrane diffusion measurements in dilute solution. Solubility measurements with model porphyrins showed that simple model porphyrins fit the operational definition for asphaltenes, exhibiting negligible solubility in n-heptane and orders of magnitude higher solubility in toluene. Measurement of the melting point properties enabled modeling of their solubility behaviour and showed that simple models incorporating solubility parameters (Regular solution and Flory-Huggins) were not capable of describing the observed behaviour. Diffusion measurements were done using model vanadyl porphyrins, asphaltenes, and petroporphyrins in toluene using a stirred diffusion cell equipped with ultrafiltration membranes (Ultracel YM and Anopore). The pore sizes were varied between 3-20 nm to retain aggregates while allowing free molecules to diffuse. The permeate was continuously monitored using in situ UV/Visible spectroscopy. These experiments determined that the size of the asphaltene aggregates at 1 g/L in toluene at 25C were in the range of 5-9 nm. An increase in temperature results in an increase in asphaltene mobility but does not reduce the size of the asphaltene structures below 5 nm. Likewise, a decrease in concentration to 0.1 g/L did not result in a decrease in size. It was also observed that the exclusion of a large portion of the total asphaltenes by pores < 5 nm eliminates the absorbance of visible light (>600 nm) indicating the presence of Rayleigh scattering for the aggregated species in solution. The petroporphyrins are larger than the model vanadyl porphyrins as indicated by pore hindrance effects within smaller pores. An increase in temperature results in an increase in petroporphyrin mobility, although decreasing the asphaltene concentration does not. The mobility of the vanadyl petroporphyrins is affected by the origin of the sample (Safaniya, Venezuela, Athabasca) and is therefore not universal. / Chemical Engineering

La gazéification permet de convertir la biomasse en gaz de synthèse composé principalement d’H2, de CO et de CO2. Ce gaz peut être utilisé comme combustible dans des moteurs ou pour produire du gaz naturel de synthèse. En plus du syngaz, la gazéification génère des espèces aromatiques lourdes qualifiées de goudrons, comme le toluène, le naphtalène et le phénanthrène. Ces espèces posent divers problèmes pratiques. Elles nuisent aux catalyseurs de SNG (surtout le toluène car plus abondant). Pour un emploi en moteur, les problèmes viennent des goudrons lourds qui sont condensables. L’épuration du syngaz est donc nécessaire pour permettre son utilisation. La perméation de gaz dans une membrane polymère dense est une technologie employée pour diverses séparations. En particulier, les membranes en silicone (PDMS) sont plus perméables aux vapeurs organiques qu’aux gaz. Cette propriété est déjà utilisée à grande échelle pour retirer des vapeurs légères de flux d’air à température ambiante. La séparation envisagée dans cette thèse reprend cette idée mais avec des vapeurs inhabituellement lourdes et une température de 90°C, ce qui est élevé. La perméation repose sur des lois de sorption et de diffusion. Les paramètres de sorption ont été mesurés, ceux de diffusion ont été tirés de la littérature afin de permettre des simulations. Ces dernières révèlent que l’emploi d’une membrane en PDMS est une technologie prometteuse pour l’épuration du syngaz en vue d’un emploi en moteur. En revanche, cette technologie semble incapable de séparer efficacement le toluène des gaz permanents (par manque de sélectivité), ce qui la rend inapte à épurer le syngaz en vue d’une application de type SNG. / Gasification allows to convert biomass into a synthesis gas containing mainly H2, CO and CO2. This gas can be used as a fuel in engines or to produce synthesis natural gas (SNG). In practice, heavy aromatic species named tars (such as toluene, naphthalene, phenanthrene) are generated along with syngas. These species generate various practical problems. They damage the SNG catalysts (especially toluene since it’s the most abundant). If syngas is used in a combustion engine, the problems are linked to the heaviest tars that can condense. Therefore, syngas upgrading is a key step to allow a good use. Gas permeation across a dense polymer membrane is a technology that is used for several separations. In particular, silicone membranes (PDMS) are more permeable to organic vapors than to permanent gases. This property is ever used at high scale to remove light vapors from fluxes of air or of nitrogen at ambient temperature. The separation that is considered in this study uses this idea but the vapors are heavy and the temperature is 90°C; that is, quite a high level of temperature. The permeation of species through a membrane is ruled by sorption and diffusion laws. The sorption parameters have been measured and the diffusion parameters have been obtained from literature in order to allow simulations. These simulations, show that the use of a PDMS membrane seems to be a promising technology to upgrade syngas for a use in an engine. On the other hand, this technology seems unable to efficiently separate toluene from permanent gases (because of a too low selectivity); that is, this technology is not able to upgrade syngas for use in SNG production.

Les matériaux plastiques contiennent des additifs, qui ne sont pas fixés dans la matrice polymère et risquent migrer dans les aliments. La directive européenne 2002/72 a introduit la possibilité de démontrer l’aptitude au contact alimentaire de ces matériaux à partir d’approches prédictives, dont l’application est limitée par la disponibilité de données de formulation et de physico-chimie. Ces travaux visent à adapter et développer des approches analytiques rapides pour identifier et quantifier les substances majoritaires contenues dans les plastiques et à développer une approche générique de prédiction des coefficients de partage entre des polymères et les simulants de l’aliment. Des méthodes conventionnelles d’extraction par solvant et de quantification en CLHP-UV-DEDL et CPG-DIF ont été comparées pour quatre formulations modèles de PEHD et PS. Une méthode rapide de déconvolution de spectres infrarouge d’extraits de PEHD a été développée pour identifier et quantifier les additifs. Un modèle prédictif des coefficients d’activité dans les PE et les simulants est proposé. Les contributions enthalpique et entropique non configurationnelle sont évaluées à partir d’un échantillonnage des énergies de contact paire à paire. Il est démontré que la contribution entropique configurationnelle est indispensable à la description de l’affinité de molécules de grande taille dans les simulants polaires ou non constitués de petites molécules. Des arbres de décision combinant approche expérimentale et modèle sont finalement discutés dans la logique de démonstration de la conformité et de veille sanitaire / Plastic packagings are formulated with additives, which can migrate from materials into foodstuffs. According to European directive 2002/72/EC, the ability of plastic materials to be used in contact with food can be demonstrated using modelling tools. Their use is however limited due to availability of some data, like the formulation of materials and partition coefficients of substances between plastics and food. On the one hand this work aims to develop the ability of laboratories to identify and quantify the main substances in plastic materials, and on the other hand it aims to develop a new method to predict partition coefficients between polymers and food simulants. Four formulations of both HDPE and PS were chosen and used during the work. Standard extraction methods and quantification methods using HPLC-UV-ELSD and GC-FID were compared. A new deconvolution process applied on infrared spectra of extracts was developed to identify and quantify additives contained in HDPE. Activity coefficients in both phases were approximated through a generalized off-lattice Flory-Huggins formulation applied to plastic materials and to liquids simulating food products. Potential contact energies were calculated with an atomistic semi-empirical forcefield. The simulations demonstrated that plastic additives have a significant chemical affinity, related to the significant contribution of the positional entropy, for liquids consisting in small molecules. Finally, decision trees, which combine both experimental and modelling approaches to demonstrate the compliance of plastic materials, were discussed

In modern separation design, an important part of many phase-equilibrium calculations is the mathematical representation of pure-component and mixture enthalpies. Mixture enthalpy data are important not only for determination of heat loads, but also for the design of distillation units. Further, mixture enthalpy data, when available, are useful for extending vapor-liquid equilibria to higher (or lower) temperatures, through the use of the Gibbs-Helmholtz equation. In this connection excess molar enthalpies for several binary and ternary mixtures involving ethers and hydrocarbons have been measured at the temperature 298.15 K and atmospheric pressure, over the whole mole fraction range. Values of the excess molar enthalpies were measured by means of a modified flow microcalorimeter (LKB 10700-1) and the systems show endothermic behavior. The Redlich-Kister equation has been used to correlate experimental excess molar enthalpy data of binary mixtures. Smooth representations of the excess molar enthalpy values of ternary mixtures are accomplished by means of the Tsao-Smith equation with an added ternary contribution term and are used to construct excess enthalpy contours on Roozeboom diagrams. The values of the standard deviations indicate good agreement between experimental results and those calculated from the smoothing equations. The experimental excess enthalpy data are also correlated and predicted by means of solution theories (Flory theory and Liebermann-Fried model) for binary and ternary mixtures, respectively. These solution theories correlate the binary heats of mixing data with reasonable accuracy. The prediction of ternary excess molar enthalpy by means of the solution theories are also presented on Roozeboom diagrams. The predictions of ternary excess enthalpy data by means of these theories are reasonably reliable.

In modern separation design, an important part of many phase-equilibrium calculations is the mathematical representation of pure-component and mixture enthalpies. Mixture enthalpy data are important not only for determination of heat loads, but also for the design of distillation units. Further, mixture enthalpy data, when available, are useful for extending vapor-liquid equilibria to higher (or lower) temperatures, through the use of the Gibbs-Helmholtz equation. In this connection excess molar enthalpies for several binary and ternary mixtures involving ethers and hydrocarbons have been measured at the temperature 298.15 K and atmospheric pressure, over the whole mole fraction range. Values of the excess molar enthalpies were measured by means of a modified flow microcalorimeter (LKB 10700-1) and the systems show endothermic behavior. The Redlich-Kister equation has been used to correlate experimental excess molar enthalpy data of binary mixtures. Smooth representations of the excess molar enthalpy values of ternary mixtures are accomplished by means of the Tsao-Smith equation with an added ternary contribution term and are used to construct excess enthalpy contours on Roozeboom diagrams. The values of the standard deviations indicate good agreement between experimental results and those calculated from the smoothing equations. The experimental excess enthalpy data are also correlated and predicted by means of solution theories (Flory theory and Liebermann-Fried model) for binary and ternary mixtures, respectively. These solution theories correlate the binary heats of mixing data with reasonable accuracy. The prediction of ternary excess molar enthalpy by means of the solution theories are also presented on Roozeboom diagrams. The predictions of ternary excess enthalpy data by means of these theories are reasonably reliable.

The goal of this project was to develop a non-toxic amphiphilic diblock copolymer nanoparticulate drug delivery system that will solubilize paclitaxel (PTX) and retain the drug in plasma. Methoxy poly(ethylene glycol)-block-poly(ε-caprolactone) (MePEG-b-PCL) diblock copolymers loaded with PTX were characterized and their physicochemical properties were correlated with their performance as nanoparticulate drug delivery systems. A series of MePEG-b-PCL was synthesized with PCL blocks ranging from 2-104 repeat units and MePEG blocks of 17, 44 or 114 repeat units. All copolymers were water soluble and formed micelles except MePEG₁₁₄-b-PCL₁₀₄, which was water insoluble and formed nanospheres. Investigation of the effects of block length on the physicochemical properties of the nanoparticles was used to select appropriate copolymers for development as PTX nanoparticles. The critical micelle concentration, pyrene partition coefficient and diameter of nanoparticles were found to be dependent on the PCL block length. Copolymers based on a MePEG molecular weight of 750 g/mol were found to have temperature dependent phase behavior. Relationships between the concentration of micellized drug and the compatibility between the drug and core-forming block, as determined by the Flory-Huggins interaction parameter, and PCL block length were developed. Increases in the compatibility between PCL and the drug, as well as longer PCL block lengths resulted in increased drug solubilization. The physicochemical properties and drug delivery performance characteristics of MePEG₁₁₄-b-PCL₁₉ micelles and MePEG₁₁₄-b-PCL₁₀₄ nanospheres were compared. Nanospheres were larger, had a more viscous core, solubilized more PTX and released it slower, compared to micelles. No difference was seen in the hemocompatibility of the nanoparticles as assessed by plasma coagulation time and erythrocyte hemolysis. Micellar PTX had an in vitro plasma distribution similar to free drug. The majority of micellar PTX associated with the lipoprotein deficient plasma fraction (LPDP). In contrast, nanospheres were capable of retaining more of the encapsulated drug with significantly less PTX partitioning into the LPDP fraction. In conclusion, although both micelles and nanospheres were capable of solubilizing PTX and were hemocompatible, PTX nanospheres may offer the advantage of prolonged blood circulation, based on the in vitro plasma distribution data, which showed that nanospheres retained PTX more effectively.