Name: WALBER RONCONI DOS SANTOS

Publication date: 25/02/2019
Advisor:

Name	Role
EDSON JOSE SOARES	Co-advisor *
RENATO DO NASCIMENTO SIQUEIRA	Advisor *

Examining board:

Name	Role
FABIO DE ASSIS RESSEL PEREIRA	External Examiner *
JAIR CARLOS CHECON DE FREITAS	External Examiner *
RENATO DO NASCIMENTO SIQUEIRA	Advisor *

Summary: The drag reduction phenomenon by addition of small amounts of polymer has been known for more than 70 years. The synthetic polymers Polyethylene Oxide (PEO) and Polyacrylamide (PAM) and the biological polymer Xanthan Gum (XG) are some of the most used drag reducing agents. Research on a recent biopolymer, called Diutan Gum (DG), shows promising results concerning its drag reduction ability. However, its rheological characteristics and advantages compared to other polymers lack further information. With this objective, the diutan gum is analyzed in terms of viscosity, storage and loss moduli, and its effects as a drag reducing agent. It is verified that the diutan gum presents high pseudoplastic behavior, even for concentrations as low as 25 ppm. The elastic modulus is more prominent than the viscous modulus for a wide frequency range and concentrations above 750 ppm. In the experiments, the reduction of drag provided by diutan gum is compared with that of PEO, PAM and XG. In addition, the results are shown in terms of pressure drop and relative drag reduction. It is noted that diutan gum is poorly de-aggregated and leads to a superior drag reduction compared to other polymers. Diutan gum, like any biopolymer, experiences biological degradation, but it can preserve good results up to 10 days after the preparation of the solution. The effect of the DG and PEO blending is also investigated. In addition to the results indicating positive synergy from the rigid polymer with flexible, the blend attenuated the effects of the degradation suffered by the synthetic.
Keywords: Polymer solution. Drag reduction. Degradation. Sinergy.

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