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Previous issue date: 2017-04-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O reparo de estruturas comp?sitas danificadas a fim de recuperar condi??es iniciais
e atender requisitos regulat?rios pode ser um grande desafio. Assim, materiais
capazes de se auto-reparar quando danificados s?o de grande interesse. Em uma
das abordagens de auto-reparo estudada na literatura, um material termopl?stico ?
adicionado ? matriz termofixa e o material danificado ? capaz de parcialmente
recuperar suas propriedades mec?nicas depois de um ciclo de reparo. Essa t?cnica
usa calor para reestabelecer parcialmente as propriedades mec?nicas do material
comp?sito. No presente estudo, a modifica??o de resina ep?xi com a adi??o de
poli(etileno-co-metil acrilato-co-glicidil metacrilato) (E-MA-GMA) foi avaliada. A
influ?ncia do tipo de endurecedor (anidrido e amina) empregado nas propriedades
do material tamb?m foi investigada. An?lises din?mico-mec?nicas (DMA) foram
realizadas para averiguar mudan?as nas propriedades viscoel?sticas devido a
adi??o do termopl?stico. Mudan?as qu?micas nas misturas termopl?stico-ep?xi
foram avaliadas por espectroscopia de infravermelho por transformada de Fourier
(FTIR). Microscopia de for?a at?mica (AFM) foi empregada para examinar o papel
da adi??o de termopl?stico na estrutura da rede do ep?xi. A habilidade de reparo foi avaliada comparando ?reas danificadas por uma
indenta??o padr?o na superf?cie das amostras antes e depois do ciclo de reparo
para amostras com e sem a adi??o de E-MA-GMA. Os resultados sugerem a
presen?a de uma segunda fase de E-MA-GMA ap?s a cura, um aumento na
temperatura de transi??o v?trea (Tg) para todas as misturas com termopl?stico
quando comparadas ? ep?xi pura, a presen?a de uma ?nica Tg para misturas EMA-
GMA-ep?xi curadas com anidrido e mudan?as qu?micas e estruturais na rede
ep?xi devido ? adi??o de E-MA-GMA. Al?m disso, o desaparecimento de danos
causados por indenta??es em ?reas do material modificado com o termopl?stico
depois do ciclo de aquecimento confirmam o potencial no uso de E-MA-GMA como
agente de reparo. / Repair of damaged composite structural elements to restore pristine conditions and
meet regulatory requirements can be a great challenge. Thus, materials capable of
self-healing when damaged are of great interest. In one of the self-healing
approaches studied in the literature, thermoplastic is added to a thermosetting matrix
and the damaged material partially recovers its mechanical properties after a healing
cycle. This technique employs heat to trigger the healing process and partially reestablish
the mechanical properties of the composite material. In the present study,
poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (E-MA-GMA)
thermoplastic was added to epoxy matrix and evaluated as a self-healing agent. The
influence of the type of hardener employed (anhydride or amine) on the properties of
the material was also investigated. Dynamic mechanical thermal analysis (DMTA)
was performed to evaluate changes in viscoelastic properties due to the addition of
thermoplastic. Fourier transform infrared (FTIR) spectroscopy was used to evaluate
chemical alterations in thermoplastic-epoxy systems. Atomic force microscopy (AFM)
was employed to examine the role of thermoplastic addition on epoxy network
structure. Healing ability was assessed by comparison of areas damaged by
indentations on the surface of samples before and after a healing cycle for materials
with and without E-MA-GMA addition. Results suggest the presence of a E-MA-GMA
second phase after curing, an increase in glass transition temperature (Tg) for all
thermoplastic blended samples as compared to neat epoxy, the presence of one
single Tg for epoxy anhydride hardened E-MA-GMA mixtures and chemical and
structural alterations on the epoxy network due to addition of E-MA-GMA. Further,
the elimination of visible damage areas of the material modified with thermoplastic
after a heating cycle supports the potential use of E-MA-GMA as healing agent.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/23776 |
| Date | 28 April 2017 |
| Creators | Guerra, ?rick St?fano Silveira |
| Contributors | 04561659676, http://lattes.cnpq.br/3718650566004689, Ferreira, Evans Paiva da Costa, 72074094434, http://lattes.cnpq.br/6994798590609919, Melo, Jos? Daniel Diniz, 46660640444, http://lattes.cnpq.br/6572298923055649, Nascimento, Maria Carolina Burgos Costa do, 03449466496, Cioffi, Maria Odila Hilario, 09840732803, http://lattes.cnpq.br/6119671014416126, Barbosa, Ana Paula Cysne |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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