Banca de DEFESA: RÓGERSON RODRIGUES FREIRE RAMOS
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.DISCENTE : RÓGERSON RODRIGUES FREIRE RAMOS
DATA : 02/02/2017
HORA: 14:00
LOCAL: Sala de Aula PPGCEM
TÍTULO:
PALAVRAS-CHAVES:
SBS, nanofibras, compositos
PÁGINAS: 127
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
RESUMO:
Structures produced from bioresorbable polymers are of great interest because of their potential uses in medical applications. In this work, a process of production of micro and nanofibrous tubular structures by solution blow spinning (SBS) was developed, using a multi-ejection matrix and a collection system based on a rotational conical collector. The process also includes an extracting step and post-spinning process by heat treatment in oven. Poly(D, L lactic acid), PDLLA, fibrous tubules were produced. The effects of collection and heat treatment on their morphological properties (SEM), crystallinity (DSC and DXR), diameter distribution, hydrophobicity (contact angle) and mechanical properties such as modulus of elasticity, stress and strain at rupture (tensile test) were evaluated. DSC analyzes indicated an increase in fiber crystallinity with increasing heat treatment time and temperature and SEM images indicated that the average fiber diameter tends to decrease at the beginning of crystallization. Wettability tests indicated that the surface energy of the material does not change significantly as a function of the degree of crystallinity. The results of the tensile tests showed that the degree of crystallinity is determinant for the mechanical performance of the mats that form the wall of the tubular structures and that the heat treatment raises the modulus of elasticity and reduces the deformation at break. The tubules submitted to the intermediate levels of heat treatment (85 ° C for 3.5 min) presented mechanical performance similar to that of samples treated at the highest levels (115°C for 6.5 min) and the tensile properties were comparable to those of Saphenous vein of an adult person. Analysis of the influence of the collection variables on mechanical properties of the tubules indicated that an increase in spinning gas pressure and a reduction in the diameter of the extractor increases elastic modulus and the tensile strength without significantly affecting the deformation at break. The angular velocity of the conical collector did not interfere in the mechanical behavior of the tubules. In summary, it was possible to produce micro and nanofibrous tubules with great potential in angiogenesis by combining SBS with an appropriate winding and extraction process.
MEMBROS DA BANCA:
Interno - 2042234 - ANA PAULA CYSNE BARBOSA
Externo à Instituição - ELITON SOUTO DE MEDEIROS - UFPB
Presidente - 1202134 - JOSE DANIEL DINIZ MELO
Externo à Instituição - JULIANO ELVIS DE OLIVEIRA - UFLA
Interno - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO