Geiza E. Oliveira

The Effect of Asphaltenes, Naphthenic Acids, and Polymeric Inhibitors on the Pour Point of Paraffins Solutions

The influence of asphaltenes and naphthenic acids on wax appearance temperature (WAT), wax crystals morphology, and pour point was estimated for solutions of a commercial paraffin sample dissolved in a solvents mixture. In addition, the performance of copolymers obtained by modification of ethylene‐vinyl acetate copolymers as organic deposition inhibitors (ODI) also was studied. Asphaltenes reduced the pour point and this effect increased with the increase in the asphaltenes concentration, indicating that asphaltenes interact with the paraffins to form particles with a different interaction profile. The observation of the wax crystals using optical microscopy revealed that in the absence of additives the solid wax particles form a homogeneous mass, evenly distributed throughout the whole sample having a plane lamellar structure which favor aggregation. When asphaltenes were incorporated, the particles were smaller and less well defined. At higher asphaltenes concentrations, dark particles whose surface resembled asphaltenes also were observed. Naphthenic acids caused a small increase in the pour point and when both fractions, asphaltenes and naphthenic acids, were added together, the asphaltenes seem to have their pour point reduction effect depressed. The ODI presented some efficiency as pour point reducers but, in the presence of asphaltenes, this efficiency was largely enhanced suggesting that beside the alteration of the particles an efficient dispersion mechanism is also necessary to inhibit the aggregation of the wax particles.

Espumados magnetizáveis úteis em processos de recuperação ambiental

The biodiesel production was encouraged since the entire world is looking for new energy sources. However, the biodiesel process produces large amounts of glycerin as byproduct. Therefore, innovative uses for this new glycerin source must be sought so as to avoid the collapse of the animal glycerin chain. In this context, the production of resins is interesting due to the likeness between these polymers and the petroleum, with these resins being promising as spill cleanup agents. In the present work, magnetic foams were prepared with insertion of maghemite nanoparticles into in a polymer generated from the glycerin, and were characterized using FTIR-ATR, WAXD and SAXS techniques. In addition, the magnetic force and the oil removal capability of these materials were also studied. The results are encouraging because nanocomposites were obtained which possess magnetic forces larger than for pure maghemite. Furthermore, this nanocomposite is able to remove a petroleum mass around 300% larger than the used mass of the composite, which means that the composite may be important for avoiding environmental disasters owing to the oil spill on the water.

Modificação da Fibra de Coco com Polianilina e o seu Uso como Sensor de Pressão

O presente trabalho teve por foco a modificacao de fibras de coco, tornando-as materiais compositos condutores de eletricidade. Para tanto, foi utilizada uma tecnica de polimerizacao in situ, capaz de gerar nanoparticulas de polianilina sobre a superficie de fibras tratadas. As fibras modificadas com polianilina foram caracterizadas por FTIR, UV-Vis, DRX e SAXS. Alem disso, foram submetidas a ensaios eletromecânicos, com a finalidade de indicar quais condicoes de modificacao sao mais eficientes para a obtencao de um material sensivel a esforcos compressivos. Os resultados de sensibilidade a compressao sugerem que os materiais modificados com as menores quantidades de polianilina sao os mais adequados para aplicacoes no campo de sensores de pressao de natureza resistiva, podendo ser utilizados no desenvolvimento de dispositivos inteligentes.

Estudo das propriedades mecânicas e elétricas de fibras de curauá modificada com polianilina

Natural fibers have been employed as reinforcement filler in composite materials for the automobile industry. Among the natural fibers, the curaua fiber is promising due to its high mechanical resistance associated with low density values. In this work curaua fibers are chemically modified by a conducting polyaniline coating, with the aim of using this new conductive composite as pressure sensors. The composite material obtained was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and optical microscopy. The results demonstrated that the methodology adopted was efficient in forming a partial, but effective, coating of the fiber, thus leading to conducting paths along the whole fiber. The electro-mechanical properties of the fibers were also evaluated and the composites have potential for low cost pressure sensors. Furthermore, the modified fibers had good thermal stability and the partial coating allows the composite to be naturally degraded as an environmentally-friendly material.

Influence of PLGA and PLGA-PEG on the dissolution profile of oxaliplatin

Oxaliplatin was inserted into polymeric matrices aiming to study the interaction of this drug with these polymers and its capability to diffuse to the environment. Tested polymers were: (1) polyethylene glycol (PEG), (2) poly(lactic-co-glycolic acid) (PLGA), and (3) a copolymer of them (PLGA-PEG). The latter two were synthesized by us using polycondensation in bulk. Oxaliplatin was included in the matrices by the melt mixing process followed by casting. Fourier tran sform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR) and X-ray diffraction (DRX) studies of the polymers were performed proving the obtaining of the desired materials. In addition, the interaction between drug and matrices and the release profile of the oxaliplatin from these matrices were analyzed. Among them, PEG did not control the oxaliplatin release. In turn, PLGA and PLGA-PEG present drug release profiles quite similar. Oxaliplatin was completely released from PLGA and PLGA-PEG in 5 hours, by a relaxation mechanism. There was no evidence of oxaliplatin interaction with the different polymers. In addition, as the PEG improves the biocompatibility and biomasking, obtained results prove the obtaining of a drug release system, which allowed the total use of the drug improving the cancer treatment and even the welfare of the patients.

Extrinsically magnetic poly(butylene succinate): An up-and-coming petroleum cleanup tool

This work presents the synthesis and characterization of extrinsically magnetic poly(butylene succinate) (PBS). PBS is obtained from succinic acid (SA), which can be efficiently produced from renewable biomass by fermentation. Thus, the use of SA helps to remove CO2 from the atmosphere, constituting a good way to accumulate carbon credits. The magnetic PBS here presented was prepared by fusion using different amounts of maghemite. Obtained materials were characterized using Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), X-ray diffraction (XRD), Small angle X-ray scattering and magnetic force tests. Besides, the oil removal capability (OR) of the samples was also studied. All the magnetic composites were able to remove petroleum from the water. Among them, the one filled with the highest amount of magnetic particles was able to remove 11 g of oil per gram of composite. Also, XRD and SAXS results showed that PBS is a long size oriented material, which allows it to work as a thermoset, avoiding its dissolution in organic contaminant medium. As PBS can also be considered as a platform, these are promising results for the oil spill cleanup applications.

The biodegradative effect of Tenebrio molitor Linnaeus larvae on vulcanized SBR and tire crumb

The overall world consumption rate of rubber tends to increase by an average of 2.8% per year in the period between 2017 and 2025. Rubber residues represent a severe problem to both health and environment due to their cross-linked structure that offers a prolonged degradation rate. A good solution to eliminate this problem is recycling and recovery, aiming at the production of new materials. The tire crumb can be recycled by chemical/biological recovery, where the elastomer is devulcanized, or by physical recovery, where the three-dimensional network is transformed into small fragments. In this study, we investigated the bio-degradation effect caused by Mealworms (the larvae of Tenebrio molitor Linnaeus) on vulcanized SBR-rubber and tire crumb as a desulphurization method. The surface modifications of both rubbers were studied by instrumental techniques: FTIR-ATR, TGA, XRD, and SEM. The cross-linking degree of the rubber was determined via circular condensation method. The obtained results show that the Tenebrio molitor could survive after three weeks of direct contact with SBR-rubber and tire crumb as the only alimentation. There was a declining effect of cross-linking degree by increasing the contact time between the rubbers and larvae. The FTIR results indicate surface/chemical modifications of the rubbers and the SEM results show the free sulfur after it was released in the form of sulfur flower-like. Also, the TGA results highlight a difference in the degrading behavior and residues of the treated and non-treated rubbers. Therefore, the reported results were promising, demonstrating the biodegradation effect caused by the Tenebrio molitor mealworms, highlighting an alternative and natural mean of degrading vulcanized rubber residues.