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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.

IntroduçãoAs companhias de petróleo têm intensificado a exploração offshore, onde os campos são localizados abaixo do fundo do mar. Neste caso, a baixa temperatura da água provoca um resfriamento brusco do óleo, ocasionando deposição de parafinas. O fenômeno de cristalização de parafina pode ser dividido em três estágios: a nucleação, onde o primeiro núcleo aparece; o segundo estágio, onde a massa produzida sai de solução; e o terceiro, onde ocorre a agregação dos cristais produzidos dando origem a cristais maiores [1][2][3] . O fenômeno de precipitação de parafina pode ocorrer devido à ação de três mecanismos: (i) efeito termodinâmico, onde a redução de temperatura e o abaixamento da pressão provocam a precipitação e uma posterior deposição dos cristais que saem de solução; (ii) efeito da estrutura molecular, onde a linearidade da parafina e o seu alto peso molecular facilitam a sua agregação; (iii) efeito fluido-dinâmico, onde um regime turbulento, que provoca uma difusão molecular e uma dispersão cisalhante, favorece uma maior troca tér-mica e, conseqüentemente, a saída da parafina de solução; e um regime laminar, que provoca o ancoramento e aderên-cia na parede e, ainda, alinha esses cristais favorecendo a deposição da parafina [4] . Atualmente esse problema de deposição de parafina é controlado pela Petrobrás através de três métodos: (1) o preditivo, onde são feitas modelações moleculares e simulações numérica e física; (2) o preventivo, onde se emprega inibição química, inibição magnética e isolamento térmico; (3) o corretivo, onde são aplicadas uma remoção Resumo: O desafio da produção de óleos parafínicos e óleos pesados tem sido destaque no cenário de inovações tecnológicas na indústria do petróleo. Este trabalho apresenta a obtenção de um novo aditivo químico de base polimérica, e sua avaliação como modificador da cristalização de parafinas de petróleo. O polímero foi obtido pela reação de éster fosfórico de cadeia longa e aluminato de sódio, de modo a gerar uma molécula de peso molecular relativamente alto e de caracterís-ticas anfifílicas. Os estudos foram realizados utilizando um sistema-modelo de parafina de petróleo (P140) dissolvida em solvente parafínico. Ensaios reológicos, calorimétricos, cromatográficos e de microscopia óptica e eletrônica de varredura evidenciaram a ação do aditivo como modificador da cristalização de parafinas, sendo que a eficiência se mostrou dependente do peso molecular do polímero. Palavras-chave:Aditivos poliméricos, éster fosfórico, parafinas de petróleo, calorimetria, morfologia. Evaluation of Polymeric Phosphoric Ester-Based Additives as Modifiers of Paraffin CrystallizationAbstract: The challenge of producing paraffinic and heavy oils plays an important role in the scenario of technological innovations in the petroleum industry. This work presents the synthesis of a new polymer-based chemical additive, and its evaluation as inhibitor of petroleum paraffin deposition. This polymer was obtained by reacting a long chain phosphoric ester with sodium aluminate, generati...

The challenge of producing paraffinic and heavy oils plays an important role in the scenario of technological innovations in the petroleum industry. This work presents the synthesis of a new polymer-based chemical additive, and its evaluation as an inhibitor of paraffin crystallization. This polymer was obtained by reacting a long-chain phosphoric ester with sodium aluminate, generating a molecule with relatively high molecular weight and amphiphilic character. The studies were carried out using a model-system of petroleum paraffin (P140) dissolved in paraffin solvent. Rheological, calorimetric, chromatographic and optical and electron microscopy tests demonstrated that the additive acts as modifier of paraffin crystallization, although the efficiency shown depended on the polymer molecular weight. Introduction The paraffinic deposit formation phenomenon is common in the oil industry and occurs as a result of modifications to the thermal dynamic variables that alter the solubility of the paraffin fractions present in petroleum. The paraffination phenomenon mainly involves the straight-chain and high molecular weight saturated hydrocarbons, during the oil production, displacement and treatment stages. Deposition in subsea flow lines, surface equipment, and production strings or even in the reservoir rock can cause significant and increasing oil production losses. [1–6]. The paraffin crystallization phenomenon may be divided into three stages: nucleation, where the first nucleus appears; the second stage, where the produced mass leaves the solution; and the third, where the aggregation of produced crystals occurs and larger crystals are formed [1–6]. The paraffin precipitation phenomenon may occur due to three mechanisms:the thermal dynamic effect, where the temperature reduction and the lowering of pressure causes the precipitation and a later deposition of crystals that leave the solution;the molecular structure effect, where the linearity of the paraffin and its high molecular weight facilitate their aggregation;the fluid dynamic effect, where a turbulent regime which provokes molecular diffusion and a shearing dispersion, favoring a greater thermal exchange and, consequently, paraffin leaving the solution; and a flow regime, which provokes anchoring and adherence to the walls and, also, aligns these crystals, favoring paraffin deposition [4]. Currently PETROBRAS controls this paraffin deposition problem by three methods:the predictive, where molecular models and numerical and physical simulations are made;the preventive, where chemical and magnetic inhibition [5] and thermal insulation are used;the corrective, where physical-chemical removal is carried out by a nitrogen generator system (SGN) [6] or mechanical removal with the use of pigs [1, 6]. Bearing in mind that the problems arising from the paraffination process do not have a single solution, and are strongly associated to the flow conditions and the petroleum's chemical nature, various scientific research has been carried out. With the objective of optimizing oil flow, various studies prove that some polymeric additives especially block copolymers, have the ability to alter the rheological properties of oil. These additives inhibit paraffin deposition below the wax appearance temperature (WAT) in the oil, as they have, predominantly, in their structure a, aliphatic portion similar to that of paraffin, attracting the crystals and, in a smaller quantity, a differential group that impedes their aggregation. One big advantage in the application of these inhibitors is their high performance in extremely low concentrations, therefore being economically viable for the flow of oil in higher volumes [1,2,4,5–9].