Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-09-04T20:41:24Z No. of bitstreams: 1 ErickStefanoSilveiraGuerra_DISSERT.pdf: 8653820 bytes, checksum: 2aa743da5d1ccc3d04ee5e239d05a6c2 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-09-06T19:52:51Z (GMT) No. of bitstreams: 1 ErickStefanoSilveiraGuerra_DISSERT.pdf: 8653820 bytes, checksum: 2aa743da5d1ccc3d04ee5e239d05a6c2 (MD5) / Made available in DSpace on 2017-09-06T19:52:51Z (GMT). No. of bitstreams: 1 ErickStefanoSilveiraGuerra_DISSERT.pdf: 8653820 bytes, checksum: 2aa743da5d1ccc3d04ee5e239d05a6c2 (MD5) 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.