In this study, microparticles of poly(lactic acid) (PLA) were produced to encapsulate cardanol, varying molar mass of the polymer matrix, concentration of the emulsifier (PVA) and concentration of the chemical additive (cardanol). The droplet size distribution, polydispersity index, morphology, the interaction between cardanol and PLA, cardanol encapsulation efficiency and release profile of this chemical additive were assessed. The morphological characterization showed that the microparticles containing cardanol were presented as microcapsules up to a maximum cardanol concentration limit that could be incorporated. The addition of cardanol during the production of the microparticles led to an increase in the average diameter of the microparticles obtained, both those with low and high molar mass (MPLA3 and MPLA100, respectively), with the increase depending on the quantity of cardanol incorporated. DSC results showed a shift in melting point and a change in Tg and Tm with the incorporation of cardanol, suggesting an interaction between cardanol and PLA matrix. Higher encapsulation efficiency and slower release of cardanol were achieved when using microparticles with higher molar mass (MPLA100). The microparticles of MPLA100/1PVA/50C provided the slowest additive release among the formulations tested. Therefore, the processes for encapsulation and controlled release of cardanol in the PLA matrix were efficient.

Asphaltenes are blamed for various problems in the petroleum industry, especially formation of solid deposits and stabilization of water-in-oil emulsions. Many studies have been conducted to characterize chemical structures of asphaltenes and assess their phase behavior in crude oil or in model-systems of asphaltenes extracted from oil or asphaltic residues from refineries. However, due to the diversity and complexity of these structures, there is still much to be investigated. In this study, asphaltene (sub)fractions were extracted from an asphaltic residue (AR02), characterized by NMR, elemental analysis, X-ray fluorescence and MS-TOF, and compared to asphaltene subfractions obtained from another asphaltic residue (AR01) described in a previous article. The (sub)fractions obtained from the two residues were used to prepare model-systems containing 1 wt% of asphaltenes in toluene and their phase behavior was evaluated by measuring asphaltene precipitation onset using optical microscopy. The results obtained indicated minor differences between the asphaltene fractions obtained from the asphaltic residues of distinct origins, with respect to aromaticity, elemental composition (CHN), presence and content of heteroelements and average molar mass. Regarding stability, minor differences in molecule polarity appear to promote major differences in the phase behavior of each of the asphaltene fractions isolated.

O parâmetro de solubilidade (δ) de uma molécula é extremamente importante, visto que novas moléculas são frequentemente desenvolvidas para serem aplicadas em sistemas líquidos. Neste trabalho, nós buscamos técnicas alternativas simples e confiáveis para determinar δ de moléculas de baixa e alta massa molar. Pireno, fenantreno e naftaleno tiveram seus δ determinados por microcalorimetria (µDSC), ultravioleta (UV) e calorimetria (DSC). Resultados de UV foram similares àqueles obtidos por DSC e àqueles citados na literatura. Amostras de poliestireno e poliestireno sulfonado tiveram seus δ determinados por UV, µDSC e viscosidade intrínseca ([η]). Os resultados de [η] foram similares àqueles obtidos por UV. Procedimento de UV foi relativamente simples, de fácil operação e confiável para determinação de δ de moléculas de ampla faixa de massa molar, podendo ser utilizado no desenvolvimento de novas moléculas. O procedimento utilizando μDSC ainda requer alguns ajustes a fim de torná-lo mais preciso do que [η].

The solubility parameter (δ) of a molecule is extremely important, since that new molecules are frequently developed to be applied in liquid systems. In this work, we looked for simple and reliable alternative techniques to determine δ of low and high molecular weight molecules. Pyrene, phenanthrene and naphthalene had their δ determined by microcalorimetry (µDSC), ultraviolet (UV) and calorimetry (DSC). UV results were similar to those obtained by DSC and to those cited in the literature. Polystyrene and sulfonated polystyrene samples had their δ determined by UV, µDSC and intrinsic viscosity ([η]). The [η] results were similar to those obtained by UV. UV procedure was relatively simple, easy operation and reliable for determining δ of molecules in a wide range of molar mass, can be used when developing new molecules. The µDSC procedure still requires some adjustments to become more accurate than [η] procedure.

The objective of this work was to use the high-pressure homogenizer (HPH) to prepare stable oil/water nanoemulsions presenting narrow particle size distribution. The dispersions were prepared using nonionic surfactants based on ethoxylated ether. The size and distribution of the droplets formed, along with their stability, were determined in a Zetasizer Nano ZS particle size analyzer. The stability and the droplet size distribution in these systems do not present the significant differences with the increase of the processing pressure in the HPH). The processing time can promote the biggest dispersion in the size of particles, thus reducing its stability.