Tese
Novas estratégias para valorização do extrato de tanino
Fecha
2017-07-21Autor
Missio, André Luiz
Institución
Resumen
In a world looking for low environmental impact products, the correct use of each biological
resource is needed. Condensable tannins are present in many natural sources and they are the
second most abundant phenolic compound in the Earth, behind only of the lignin. Based on
both the worldwide production of this phenolic extract and the increase in the researches to
improve the use of raw materials, this doctoral thesis aimed to elaborate new strategies toward
the valorization of the tannin extract. Mimosa tannin (Acacia mearnsii De Wild) was first
purified to remove carbohydrates and acids to obtain new fractions of the extract. The tannin
was fractionated using organic solvents with different polarities in a Soxhlet extraction system
with single and sequential processes. After that, wood-plastic composites were made using
tannin as a natural compatibilizer to apply the Mimosa industrial tannin into products or new
materials. The composites were prepared with polypropylene, pine sawdust and wood fibers
through a thermokinetic homogenizer and a hydraulic press. Finally, the tannin was
incorporated into the nanocellulose to develop a film for application in active packaging.
Cellulose and tannin were mixed with distilled water in a mechanical fibrillation
microprocessor, forming a homogeneous gel with nanofibrillated cellulose and tannin. Using a
vacuum filtration system, the gel was converted into a film. The main results obtained through
specific characterizations of the fractions, composites and films were very positive. Different
properties were observed in the fractions, and it was possible to target the material obtained for
specific purposes, such as for pharmaceuticals and active packaging (lower molecular weight
and higher antioxidant capacity) and adhesives (higher molecular weight). Increases in the
storage modulus and in the hydrophobicity were obtained from the incorporation of the tannin
into wood-plastic composites, besides a compatibilization to be confirmed by morphological
analysis. Finally, the films of nanocellulose and tannin presented high antioxidant properties,
which was released from the contact with water. Furthermore, the films showed high
mechanical strength and barrier capacity, indicating their for application as active packaging
for foods and drugs. Therefore, we believe that the tannin extract can and should be used for
the elaboration of higher value-added materials, mainly due to its chemical structure, abundance
and sustainable production cycle.