Name: Leandro Motta Leal
Type: MSc dissertation
Publication date: 25/04/2018

Namesort descending Role
Edson Jose Soares Advisor *
Renato do Nascimento Siqueira Co-advisor *

Examining board:

Namesort descending Role
Edson Jose Soares Advisor *
Jair Carlos Checon de Freitas External Examiner *
Renato do Nascimento Siqueira Co advisor *
Sandro José Greco External Examiner *

Summary: The addition of small amounts of polymer to turbulent flow produces a significant reduction of the friction factor. This phenomenon, known as drag reduction, has been studied by many researchers since it was reported by Toms (1948) due its importance and wide applicability. However, most polymers commonly used as a drag reducer are synthetic. They are poorly resistant to high shear rates and are toxic, factors that do not allow the use of these materials in certain applications, such as in the medical field and the environment. Thus, the search for natural additives that reduce drag increases over time, because these materials are generally more resistant, biodegradable and non-toxic, reasons that make them a good alternative to replace synthetic polymers in some applications. The present work proposes a more detailed study about mucilage of aloe vera plant as a natural reducing agent. To do this, the tests are performed using a rotating geometry composed of double-gap concentric cylinders and an experimental apparatus formed by a tube system with flow rate and pressure controlled. The analyzes focused on assessing whether aloe vera leaves of varying ages had different efficiencies to reduce drag. For this, a methodology was created to estimate leaf age and separate the material into young, intermediate and mature leaves. Thereafter, with the production of the test samples, the drag reduction experiments are conducted at the same concentration among different ages, in both the rheometer and the experimental apparatus. In addition, Magnetic Resonance tests are performed to evaluate the chemical composition of each age of the aloe vera sample and to estimate which constituent possibly acts most intensively in the phenomenon of drag reduction.

Key words: biopolymer, drag, efficiency, constituent

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