Banca de QUALIFICAÇÃO: MARIA PAULA DE CARVALHO FREIRE
Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.STUDENT : MARIA PAULA DE CARVALHO FREIRE
DATE: 05/05/2023
TIME: 09:00
LOCAL: meet.google.com/sjj-wksu-azs
TITLE:
Optimization of poly(urea-formaldehyde) (PUF) polymeric microcapsules filled with 5-ethylidene-2-norbonene synthesis for self-healing using factorial design methodology
KEY WORDS:
Self-healing; in situ polymerization; polymeric microcapsules; factorial design; poly(urea-formaldehyde).
PAGES: 70
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Polímeros, Aplicações
SUMMARY:
In the recent decades, researches on materials with self-healing capacity has progessively increased, and self-healing systems with polymeric microcapsules are included in the solutions proposed to repair the damage due to the appearance of cracks that structurally compromisse the lifetime of the material during use, enabling a reduction in costs. In this work, poly(urea-formaldehyde) (PUF) microcapsules filled with 5-ethylidene-2-norbonene (ENB) were prepared by in situ emulsion polymerization. A previous analysis of works developed using a Plackett-Burman (PB) design with seven factors helped in the selection of variables to be used in a fractional fatorial design 24-1 and, based on this, it was possible to select the significant variables as 90% confidence to perform a complete factorial design with three factors, in order to optimize the synthesis process. The parameters chosen for the fractional design included: the agitation speed, the poly(ethylene-alt-maleic) (EMA) content that act as na emulsifier, the drops of 1-octanol (stabilizes the emulsion inhibiting the formation of bubbles) and the pH of the reaction. The responses evaluated were the médium diameter of the microcapsules, the yield, the encapsulate contente, the termal stability and the degradation temperature. From the parameters analyzed, the EMA content, the pH of the reaction and the agitation speed should be used in the complete design due to their significant effects on the response variables analyzed, using a confidence level of 90%. In a previous analysis to the pomplete design, considering the analyzed response variables, microcapsules with satisfactory Properties for applications in self-healing were obtained in the condition in which the agitation speed and the EMA contente were at higher levels, and the pH was at the lower level, corresponding to the synthesis of PUF/ENB 4 of the fractional design. However, to obtain the optimal conditions of the synthesis process, it is required the development of the complete fatorial design using as controlled variables the agitation speed, the EMA content and the pH, and the application of microcapsules obtained in the optimal conditions for evaluation of the capacity of self-healing through mechanical tests. These will be the next steps of this work.
COMMITTEE MEMBERS:
Presidente - 1755267 - MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
Interno - 1202134 - JOSE DANIEL DINIZ MELO
Externa à Instituição - MARIA INGRID ROCHA BARBOSA SCHIAVON