Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent
Epoxy matrix composites are often subjected to adverse service conditions leading to the formation of microcracks. Microcracks are of great concern because they can act as nucleation sites for more prejudicial types of damage, such as delamination. Among the solutions to mitigate the deleterious...
Na minha lista:
| Autor principal: | |
|---|---|
| Outros Autores: | |
| Formato: | doctoralThesis |
| Idioma: | pt_BR |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
|
| Assuntos: | |
| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/50952 |
| Tags: |
Adicionar Tag
Sem tags, seja o primeiro a adicionar uma tag!
|
| id |
ri-123456789-50952 |
|---|---|
| record_format |
dspace |
| institution |
Repositório Institucional |
| collection |
RI - UFRN |
| language |
pt_BR |
| topic |
Compósitos de matriz epóxi Resistência interfacial Ligação fibra-matriz Autorreparo CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA |
| spellingShingle |
Compósitos de matriz epóxi Resistência interfacial Ligação fibra-matriz Autorreparo CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA Guerra, Érick Stéfano Silveira Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| description |
Epoxy matrix composites are often subjected to adverse service conditions leading to the
formation of microcracks. Microcracks are of great concern because they can act as nucleation sites
for more prejudicial types of damage, such as delamination. Among the solutions to mitigate the
deleterious effect of matrix microcracking is the use of thermoplastic healing agents. Poly(ethyleneco-methacrylic acid) (EMAA) has been particularly used as a thermoplastic healing agent because of
its suitable chemical and physical properties. When the material is heated, the thermoplastic phase
dispersed in the epoxy matrix is allowed to flow into microcracks and restore mechanical properties.
The addition of EMAA particles, however, may alter chemical and thermomechanical properties of
epoxy composites. These changes may also affect other fundamental features of epoxy composites,
such as their fiber-matrix interfacial properties. Therefore, the objectives of this work are: (1) study
the effects of EMAA addition on epoxy formation, (2) investigate the effect of EMAA addition on
fiber-matrix interfacial properties, and (3) study the potential for self-healing through
micromechanical testing. The effect of a 10 wt.% EMAA modified epoxy was investigated through
infrared spectroscopy and differential scanning calorimetry (DSC) experiments. The results
suggested that EMAA addition may cause changes during the epoxy network formation. Then, single
fiber pull-out tests were used to characterize the fiber interfacial shear strength (IFSS) of pure and
modified epoxy systems, as well as between fiber and pure EMAA. IFSS results of pure and modified
epoxy were quite similar, revealing that epoxy modification did not significantly alter fiber-matrix
interfacial properties. On the other hand, IFSS measurements of fiber-EMAA presented considerably
lower values than fiber-epoxy, suggesting that healing is most likely held by fiber-epoxy or EMAAepoxy interactions. A novel method to assess the healing efficiency (η) using optically monitored
single fiber pull-out testing was proposed. According to the data obtained, healing efficiency of
EMAA modified epoxy was lower than that of pure epoxy systems. The attenuated matrix shrinkage
effect due to the addition of rubbery EMAA particles, along with the lower IFSS results of EMAAfiber are proposed to explain the observed low η values. Complementary tests investigated
thermomechanical properties and the curing of the EMAA modified epoxy, along with the effect of
healing on the chemical structure and its IFSS properties. |
| author2 |
Melo, José Daniel Diniz |
| author_facet |
Melo, José Daniel Diniz Guerra, Érick Stéfano Silveira |
| format |
doctoralThesis |
| author |
Guerra, Érick Stéfano Silveira |
| author_sort |
Guerra, Érick Stéfano Silveira |
| title |
Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| title_short |
Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| title_full |
Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| title_fullStr |
Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| title_full_unstemmed |
Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| title_sort |
microscale evaluation of epoxy matrix composites containing thermoplastic healing agent |
| publisher |
Universidade Federal do Rio Grande do Norte |
| publishDate |
2023 |
| url |
https://repositorio.ufrn.br/handle/123456789/50952 |
| work_keys_str_mv |
AT guerraerickstefanosilveira microscaleevaluationofepoxymatrixcompositescontainingthermoplastichealingagent |
| _version_ |
1773961241127026688 |
| spelling |
ri-123456789-509522023-01-16T18:03:37Z Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent Guerra, Érick Stéfano Silveira Melo, José Daniel Diniz http://lattes.cnpq.br/0196847521512805 http://lattes.cnpq.br/6572298923055649 Barbosa, Ana Paula Cysne https://orcid.org/0000-0002-9510-4851 http://lattes.cnpq.br/3718650566004689 Kalinka, Gerhard Carvalho, Laura Hecker de Portella, Pedro Dolabella Compósitos de matriz epóxi Resistência interfacial Ligação fibra-matriz Autorreparo CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA Epoxy matrix composites are often subjected to adverse service conditions leading to the formation of microcracks. Microcracks are of great concern because they can act as nucleation sites for more prejudicial types of damage, such as delamination. Among the solutions to mitigate the deleterious effect of matrix microcracking is the use of thermoplastic healing agents. Poly(ethyleneco-methacrylic acid) (EMAA) has been particularly used as a thermoplastic healing agent because of its suitable chemical and physical properties. When the material is heated, the thermoplastic phase dispersed in the epoxy matrix is allowed to flow into microcracks and restore mechanical properties. The addition of EMAA particles, however, may alter chemical and thermomechanical properties of epoxy composites. These changes may also affect other fundamental features of epoxy composites, such as their fiber-matrix interfacial properties. Therefore, the objectives of this work are: (1) study the effects of EMAA addition on epoxy formation, (2) investigate the effect of EMAA addition on fiber-matrix interfacial properties, and (3) study the potential for self-healing through micromechanical testing. The effect of a 10 wt.% EMAA modified epoxy was investigated through infrared spectroscopy and differential scanning calorimetry (DSC) experiments. The results suggested that EMAA addition may cause changes during the epoxy network formation. Then, single fiber pull-out tests were used to characterize the fiber interfacial shear strength (IFSS) of pure and modified epoxy systems, as well as between fiber and pure EMAA. IFSS results of pure and modified epoxy were quite similar, revealing that epoxy modification did not significantly alter fiber-matrix interfacial properties. On the other hand, IFSS measurements of fiber-EMAA presented considerably lower values than fiber-epoxy, suggesting that healing is most likely held by fiber-epoxy or EMAAepoxy interactions. A novel method to assess the healing efficiency (η) using optically monitored single fiber pull-out testing was proposed. According to the data obtained, healing efficiency of EMAA modified epoxy was lower than that of pure epoxy systems. The attenuated matrix shrinkage effect due to the addition of rubbery EMAA particles, along with the lower IFSS results of EMAAfiber are proposed to explain the observed low η values. Complementary tests investigated thermomechanical properties and the curing of the EMAA modified epoxy, along with the effect of healing on the chemical structure and its IFSS properties. Compósitos de matriz epóxi estão regularmente submetidos a condições de trabalho adversas levando à formação de microtrincas. A presença de microtrincas é preocupante porque elas podem servir de sítios de nucleação para formas de danos mais prejudiciais, como delaminação. O uso de agentes de reparo termoplásticos está entre as principais soluções usadas para mitigar o efeito deletério das microtrincas. Poli(etileno-co-ácido metacrílico) (EMAA) tem sido particularmente usado como agente de reparo termoplástico em função de suas adequadas propriedades químicas e físicas. Quando calor é aplicado ao material, a fase termoplástica dispersa flui e preenche as microtrincas, assim recuperando as propriedades mecânicas. A adição de partículas de EMAA, no entanto, pode causar alterações nas propriedades químicas e termomecânicas do compósito epoxídico. Essas mudanças podem também afetar outras características fundamentais dos compósitos epoxídicos, como as propriedades interfaciais fibra-matriz. Os objetivos desse trabalho são, portanto, (1) estudar os efeitos da adição de EMAA na formação do epóxi, (2) investigar os efeitos da adição de EMAA nas propriedades interfaciais fibra-matriz e (3) estudar o potencial de autorreparo através de testes micromecânicos. O efeito da adição de 10% em peso de EMAA em epóxi foi investigado através das técnicas de espectroscopia do infravermelho e calorimetria diferencial exploratória (DSC). Os resultados sugerem que a adição de EMAA pode causar alterações na formação da rede epoxídica. Em seguida, testes de puxamento de fibra única foram usados para caracterizar a resistência ao cisalhamento interfacial (IFSS) entre fibra e os sistemas epoxídicos (puro e modificado), além de entre fibra e EMAA puro. Resultados de IFSS dos sistemas epoxídicos foram bastante similares, revelando que a modificação do epóxi não altera significantemente as propriedades interfaciais fibra-matriz. Contudo, medidas de IFSS entre fibra-EMAA apresentaram valores consideravelmente menores do que fibra-epóxi, sugerindo que a habilidade de reparo é provavelmente realizada pelas interações fibra-epóxi ou EMAA-epóxi. Um novo método para avaliar a eficiência de reparo (η) usando testes de puxamento de fibra única monitorados opticamente foi proposto. Resultados revelaram que o epóxi modificado com EMAA apresentou menores valores de η do que para o epóxi puro. As principais razões sugeridas para são a atenuação da contração de cura da matriz devido à presença das partículas borrachosas de EMAA e os baixos valores de IFSS obtidos entre fibra-EMAA. Testes complementares investigaram as propriedades termomecânicas e a cura do epóxi modificado com EMAA, assim como o efeito do reparo na estrutura química e nas propriedades IFSS. 2023-01-16T18:02:47Z 2023-01-16T18:02:47Z 2022-12-01 doctoralThesis GUERRA, Érick Stéfano Silveira. Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent. Orientador: José Daniel Diniz Melo. 2022. 96f. Tese (Doutorado em Ciência e Engenharia de Materiais) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2022. https://repositorio.ufrn.br/handle/123456789/50952 pt_BR Acesso Aberto application/pdf Universidade Federal do Rio Grande do Norte Brasil UFRN PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIA E ENGENHARIA DE MATERIAIS |