Banca de DEFESA: ANNA RAFFAELA DE MATOS COSTA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ANNA RAFFAELA DE MATOS COSTA
DATA : 19/02/2019
HORA: 08:30
LOCAL: Sala de aulas do PPGCEM
TÍTULO:

POLY (B-HYDROXYBUTYRATE) AND POLY (BUTYLENE-ADIPATE-CO-TEREPHTHALATE) BLENDS AND THEIR COMPOSITES WITH BABAÇU: EFFECT OF COMPOSITION AND PROCESSING CONDITIONS


PALAVRAS-CHAVES:
Biodegradable polymers, blends and polymer composites, babassu fiber, PBAT and PHB


PÁGINAS: 215
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Polímeros, Aplicações
RESUMO:
This work deals with PHB/PBAT blends as well as their composites with fibers extracted from two parts of the babassu fruit (epicarp and endocarp). The effect of processing conditions on the rheological, thermal and morphological properties of the composites as a function of load type and content was evaluated. PHB/ PBAT blends were processed in an internal mixer. They were characterized by torque rheometry and their crystallization and melting behavior were analyzed by differential scanning calorimetry (DSC). Composites having three different blends as the matrix and reinforced with 10 and 20 %wt. of the two kinds of fibrous loads were melt processed in an internal laboratory mixer and characterized by torque rheometry. Degradation rates, estimated by the reduction of the torque and molar mass during processing, were associated to blend composition as well as to the filler kind (epicarp or mesocarp) and content. Scanning electron microscopy was used to analyse the interface of the blends and composites, while optical microscopy was used to reveal the filler dispersion. DSC results showed that PBAT crystallizes completely during cooling while PHB and PHB/PBAT blends incompletely crystallized from the melt, the process achieving completion during the reheating step. These characteristics were independent of the heating rate and are the same for the pure polymers and for the blend with 50 %wt. of the PBAT. Pseudo-Avrami, Ozawa and Mo classical macrokinetic models were employed to describe the evolution of crystallization from the melt and it was found that none of the three classical kinetic models tested could accurately predict the experimental data for the blend. Some models can be used - as predictive tools - for pure components (Ozawa for PHB, Mo for PBAT) with a reduced validity range. The results of torque rheometry showed that PHB degraded faster during processing than PBAT and that the combination of PHB with PBAT provided significant protection against excessive degradation of PHB. Both the presence and level of the two types of filler increased the incipient degradation of the blend. The images obtained by optical microscopy (OM) showed uniform filler distribution in the matrix in all cases, without agglomerates. SEM of the fracture surface morphology indicated better matrix/fiber adhesion in mixtures rich in PHB and composites with babassu epicarp.


MEMBROS DA BANCA:
Externa ao Programa - 2254759 - AMANDA MELISSA DAMIAO LEITE
Presidente - 1639676 - EDSON NORIYUKI ITO
Externo à Instituição - ELITON SOUTO DE MEDEIROS - UFPB
Externa à Instituição - LAURA HECKER DE CARVALHO - UFCG
Interna - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
Notícia cadastrada em: 17/01/2019 08:47
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