Desenvolvimento de novos biolubrificantes hidráulicos derivados dos óleos de maracujá e de moringa in natura e epoxidados
With the increasing environmental awareness, maximizing biodegradability and minimizing ecotoxicity is the main driving force for new technological developments. Thus, can be developed new biodegradable lubricants for use in environmentally sensitive areas. The aim of this study was to obtain new...
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| Formato: | doctoralThesis |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/19767 |
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| Resumo: | With the increasing environmental awareness, maximizing biodegradability
and minimizing ecotoxicity is the main driving force for new technological developments.
Thus, can be developed new biodegradable lubricants for use in environmentally sensitive
areas. The aim of this study was to obtain new bio-lubricants from passion fruit (Passiflora
edulis Sims f. flavicarpa Degener) and moringa (Moringa oleifera Lamarck) epoxidized oils
and develop a new additive package using experimental design for their use as a hydraulic
fluid. In the first stage of this work was performed the optimization of the epoxidation process
of the oils using fractional experimental design 24-1
, varying the temperature, reaction time,
ratio of formic acid and hydrogen peroxide. In the second step was investigated the
selectivity, thermodynamics and kinetics of the reaction for obtaining the two epoxides at 30,
50 and 70 °C. The result of the experimental design confirmed that the epoxidation of passion
fruit oil requires 2 hours of reaction, 50 °C and a ratio H2O2/C=C/HCOOH (1:1:1). For
moringa oil were required 2 hours reaction, 50 °C and a ratio of H2O2/C=C/HCOOH
(1:1:1.5). The results of the final conversions were equal to 83.09% (± 0.3) for passion fruit
oil epoxide and 91.02 (±0,4) for moringa oil epoxide. Following was made the 23
factorial
design to evaluate which are the best concentrations of corrosion inhibitor and anti-wear (IC),
antioxidant (BHA) and extreme pressure (EP) additives. The bio-lubricants obtained in this
step were characterized according to DIN 51524 (Part 2 HLP) and DIN 51517 (Part 3 CLP)
standards. The epoxidation process of the oils was able to improve the oxidative stability and
reduce the total acid number, when compared to the in natura oils. Moreover, the epoxidized
oils best solubilized additives, resulting in increased performance as a lubricant. In terms of
physicochemical performance, the best lubricant fluid was the epoxidized moringa oil with
additives (EMO-ADI), followed by the epoxidized passion fruit oil with additives (EPF-ADI)
and, finally, the passion fruit in natura oil without additives (PFO). Lastly, was made the
investigation of the tribological behavior under conditions of boundary lubrication for these
lubricants. The tribological performance of the developed lubricants was analyzed on a HFRR
equipment (High Frequency Reciprocating Rig) and the coefficient of friction, which occurs
during the contact and the formation of the lubricating film, was measured. The wear was
evaluated through optical microscopy and scanning electron microscopy (SEM). The results
showed that the addition of extreme pressure (EP) and anti-wear and corrosion inhibitor (CI)
additives significantly improve the tribological properties of the fluids. In all assays, was
formed a lubricating film that is responsible for reducing the coefficient of metal-to-metal
wear. It was observed that the addition of EP and IC additives in the in natura vegetable oils
of passion fruit and moringa did not favor a significant reduction in wear. The bio-lubricants
developed from passion fruit and moringa oils modified via epoxidation presented satisfactory
tribological properties and shown to be potential lubricants for replacement of commercial
mineral-based fluids. |
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