Banca de DEFESA: CARLOS GOMES DE MOURA FILHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : CARLOS GOMES DE MOURA FILHO
DATE: 19/11/2021
TIME: 09:00
LOCAL: Virtual
TITLE:

Pressure delivery mechanism for self-healing of epoxy with embedded polyethylene-co-methacrylic acid (EMAA) particles

KEY WORDS:

Self-healing, epoxy, poly (ethylene-co-methacrylic acid)

PAGES: 75
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Materiais Conjugados Não-Metálicos
SUMMARY:

Materials with self-healing capability offer great potential to improve life and long-term reliability in many applications. Poly (ethylene-co-methacrylic acid) (EMAA) has been studied as repair agent for thermosetting polymers and the formation of bubbles has been described as a pressure delivery mechanism to push the molten thermoplastic into the crack plane, thus promoting healing. This study investigates the effects of temperature, time, and particle size of EMMA particles as parameters related to the self-healing mechanism. EMMA particle size of ≥ 355 μm and ≥ 125 μm and temperatures of 130 °C, 155 °C, and 180 °C were considered. Thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) were performed to investigate thermal properties and material degradation. Melt Flow Rate (MFR) tests were also performed on EMAA. Hot stage microscopy was used to investigate the dynamics of bubble formation resulting from condensation reactions between EMAA and epoxy. The results were compared with those observed using EMAA on a glass substrate. Thermal analysis showed no degradation of EMAA and epoxy at the temperatures considered for the healing process. The results suggest that the number of bubbles increased with time, irrespective of temperature and particle size for EMAA on epoxy or glass substrate, for promoting the pressure delivery mechanism. Then, the number of bubbles decreased with time for EMAA on the glass substrate, regardless of temperature and particle size. The collapse of bubbles was not observed in epoxy substrate for the processing times evaluated.  Ultimately, the results suggest that self-healing cycles using smaller particles (≥ 125 μm) at a temperature of 180 °C and processing times enough to consume reactional functional groups available are parameters that favor the pressure delivery mechanism with a subsequent collapse of bubbles. 

BANKING MEMBERS:
Presidente - 1202134 - JOSE DANIEL DINIZ MELO
Interna - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
Externo à Instituição - FELIPE PEDRO DA COSTA GOMES