Banca de QUALIFICAÇÃO: ANA CLÁUDIA MEDEIROS DE CARVALHO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ANA CLÁUDIA MEDEIROS DE CARVALHO
DATA : 28/04/2017
HORA: 10:30
LOCAL: Auditório do CT
TÍTULO:

SYNTHESIS OF POLY(UREA-FORMALDEHYDE) MICROCAPSULES FILLED WITH DICYCLOPENTADIENE AND ITS USE IN SELF-HEALING SYSTEMS

PALAVRAS-CHAVES:

Self-healing, microcapsules, poly(urea-formaldehyde), dicyclopentadiene, vegetable oil.

PÁGINAS: 83
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Polímeros, Aplicações
RESUMO:

Self-healing materials are a class of smart materials with an inherent ability to repair damage, thus recovering their functionality. Urea-formaldehyde microcapsules have been studied to provide self-healing functionality to polymers and polymeric matrix composites. These microcapsules must be strong enough to remain intact during processing of the host polymer, and yet break when the polymer is damaged. A well-known self-healing system comprises an epoxy matrix with urea-based microcapsules containing dicyclopentadiene (DCPD). Upon release, DCPD can undergo ring-opening metathesis polymerization (ROMP) when in contact with a pre-embedded dispersed Grubbs’ catalyst. As the healing agent encounters the embedded catalyst, a polymerization reaction is initiated and proceeds until all released healing agent is consumed. The resulting polymer (poly(DCPD) serves as a bonding agent that bridges the crack, regaining much of the initial material properties (fracture toughness, stiffness, ultimate strength, etc.). In this work, urea-formaldehyde microcapsules were synthesized by in situ polymerization in an oil-in-water emulsion. In preliminary studies, four vegetable oils (soybean, linseed, olive and coconut oil) were used in substitution of DCPD due to its acute toxicity and strong smell. The main idea was to study microcapsules synthesis using a non-toxic core material, which would later be substituted by DCPD, when microcapsule synthesis and polymer processing parameters were consolidated. The microcapsules synthesized were characterized by Fourier Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM). The preliminary results showed that it was possible to produced microcapsules made of poly(urea-formaldehyde) filled with all vegetable oils used. Most capsules synthesized presented diameter around 50 µm, a suitable size for application in epoxy matrix or epoxy coating. Tests were also conducted using DCPD as core material and the resulting microcapsules had the same characteristics compared with capsules filled with vegetable oils.

MEMBROS DA BANCA:
Interno - 2042234 - ANA PAULA CYSNE BARBOSA
Externo ao Programa - 1064594 - EVANS PAIVA DA COSTA FERREIRA
Interno - 1202134 - JOSE DANIEL DINIZ MELO
Presidente - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
Externo à Instituição - MARIA ODILA HILARIO CIOFFI - UNESP