Síntese de termorrígidos fenólicos simultaneamente à formação de compósitos: fibras e mantas como reforço vegetal

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dc.contributorUniversidade de São Paulo
dc.contributor.authorPinheiro, Francisca Gleyciara Cavalcante
dc.date.issued2020-05-26
dc.description.abstract<span style=\"font-weight: 400;\">O presente estudo visou a valoriza&ccedil;&atilde;o da fibra do mesocarpo de dend&ecirc; (FMD) e mantas de fibra de sisal (MFS, cristalinidade=57%) e rayon (MFR, cristalinidade = 47%) usando as mesmas como agente de refor&ccedil;o na prepara&ccedil;&atilde;o de comp&oacute;sitos termorr&iacute;gidos obtidos a partir de resinas fenol-formalde&iacute;do (RFF), e h&iacute;bridos constitu&iacute;dos por MFS/FMDmo&iacute;da como refor&ccedil;o de matrizes fen&oacute;licas. Foram tamb&eacute;m sintetizadas resinas substituindo 70% do fenol por lignina Kraft industrial (resina lignina Kraft-fenol-formalde&iacute;do- RLKFF), assim como substituindo o formalde&iacute;do por glutaralde&iacute;do (resina fenol-glutaralde&iacute;do- RFG). FMD, dentre outras t&eacute;cnicas tamb&eacute;m usadas para caracterizar MFS e MFR, foi caracterizada por Microscopia eletr&ocirc;nica por varredura (MEV)-acoplado com Espectroscopia por energia dispersiva (EDS), e espectrometria de emiss&atilde;o &oacute;ptica por plasma induzida por microondas (MIP-OES). As an&aacute;lises de MEV-EDS e MIP-OES indicaram que a FMD possui superf&iacute;cie rugosa com poros preenchidos por corpos circulares de sil&iacute;cio, aproximadamente 1,1% (&plusmn; 0,2), respectivamente. Os termorr&iacute;gidos e comp&oacute;sitos obtidos a partir das resinas foram caracterizados quanto &agrave;s resist&ecirc;ncias ao impacto (Izod) e &agrave; flex&atilde;o, MEV, an&aacute;lise din&acirc;micomec&acirc;nica (DMA) e Termogravimetria. Dentre as propriedades avaliadas para os comp&oacute;sitos, a resist&ecirc;ncia ao impacto foi selecionada para fins comparativos. Os resultados obtidos a partir dos comp&oacute;sitos de matriz RFF refor&ccedil;ados com FMD foram aqu&eacute;m das expectativas, como consequ&ecirc;ncia de as caracter&iacute;sticas das fibras limitarem a porcentagem em massa de fibras a 17% (resist&ecirc;ncia ao impacto 46 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">). Assim, FMD foi substitu&iacute;da por MFS e MFR. Dentre os comp&oacute;sitos de matriz RFF refor&ccedil;ados com MFS (42% em volume) o que apresentou maior resist&ecirc;ncia ao impacto, foi o que a manta foi previamente imersa em &aacute;gua (visando separa&ccedil;&atilde;o de feixes de fibras, com posterior secagem), e a viscosidade da resina foi reduzida com a adi&ccedil;&atilde;o de etanol (visando aumentar a impregna&ccedil;&atilde;o das fibras pela resina, com posterior elimina&ccedil;&atilde;o de etanol), 453 &plusmn; 32 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">. O comp&oacute;sito de matriz RFF refor&ccedil;ado com MFR (19% em volume) apresentou melhor resultado de resist&ecirc;ncia ao impacto normalizado (por unidade de porcentagem em volume de manta), 17 &plusmn; 1,2 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">, comparado ao comp&oacute;sito refor&ccedil;ado com MFS, 10 &plusmn; 0,7 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">. O comp&oacute;sito de matriz RFG refor&ccedil;ado com MFR apresentou resist&ecirc;ncia ao impacto (455 &plusmn; 62 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">) superior, aos comp&oacute;sitos similares em matrizes RFF (323 &plusmn;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 30 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">) e RLKFF (98 &plusmn; 9 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">), possivelmente devido a maior molhabilidade das mantas de rayon pela matriz RFG, devido a menor viscosidade desta resina comparativamente &agrave; RFF e RLKFF. Em todos os comp&oacute;sitos h&iacute;bridos refor&ccedil;ados por MFS/FMDmo&iacute;da (matrizes RFF, RFG e RLKFF), a FMDmo&iacute;da atuou como refor&ccedil;o adicional melhorando a propriedade de resist&ecirc;ncia ao impacto dos comp&oacute;sitos, quando comparados aos respectivos comp&oacute;sitos refor&ccedil;ados apenas por MFS. O amplo conjunto de resultados obtidos, referentes aos refor&ccedil;os, &agrave;s resinas sintetizadas e aos respectivos comp&oacute;sitos, agrega novos conhecimentos &agrave; &aacute;rea de comp&oacute;sitos termorr&iacute;gidos do tipo fen&oacute;lico refor&ccedil;ados por fibras oriundas de plantas. Os materiais obtidos apresentam potencial para aplica&ccedil;&otilde;es como isolante el&eacute;trico, partes n&atilde;o estruturais de autom&oacute;veis, aeronaves, assim como na &aacute;rea naval.&nbsp;
dc.description.abstract<span style=\"font-weight: 400;\">The present study aimed at the valorization of palm oil mesocarp fibers (OPMF), and woven mats (sisal fibers, SFWM, crystallinity = 57%, and rayon, RFWM, crystallinity = 47%) using them as reinforcing agents in the preparation of thermoset composites from phenol-formaldehyde resins, and hybrids consisting of SFWM/OPMFmilled as reinforcement of phenolic-type matrices (PhFR). Resins were also synthesized by replacing 70% of phenol by industrial Kraft lignin (Kraft lignin-phenol-formaldehyde resin - KLPhFR) as well as replacing formaldehyde by glutaraldehyde (phenol-glutaraldehyde resin- PhGR). OPMF, among other techniques also used to characterize SFWM and RFWM, was characterized by Scanning electron microscopy - coupled with Energy dispersive x-ray spectroscopy (EDS), and Microwave-induced plasma optical emission spectrometry (MIP-OES). SEM-EDS and MIP-OES analyze indicated that OPMF has a rough surface with pores filled with circular silicon bodies, approximately 1.1% &plusmn; 0.2 of silicon, respectively. Thermosets and composites obtained from resins were characterized for Impact strength (Izod) and Flexural strength, SEM, Dynamic mechanical analysis (DMA) and Thermogravimetry. Among the properties evaluated for composites, impact resistance was selected for comparative purposes. Among the properties evaluated for composites, impact strength was selected for comparative purposes. The results obtained from OPMF-reinforced PhFR matrix composites were below expectations as a consequence of the fiber characteristics limited the fiber percentage by mass to 17% (impact strength 46 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">). Thus, OPMF was replaced by SFWM and RFWM. Among the SFWM (42% by volume) reinforced PhFR matrix composites the one that presented the highest impact strength was obtained by immersion of SFWM in water (aiming fiber bundle separation, with subsequent drying) and the resin viscosity was reduced with the addition of ethanol (aiming at increasing impregnation of the fibers by the resin, with subsequent elimination of ethanol). The SFWM-reinforced PhFR matrix composite (19% by volume) showed better impact strength normalized results (per unit volume percentage of the woven mat) compared to the similar SFWM-reinforced composite. The SFWM-reinforced PhGR matrix composite showed higher impact strength (455 &plusmn; 62 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">) than similar composites in PhFR (323 &plusmn; 30 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">) and (98 &plusmn; 9 J m<span style=\"font-weight: 400;\">-1<span style=\"font-weight: 400;\">) matrices, possibly due to the higher wettability of rayon woven mat by the RFG matrix, as a consequence of the lower viscosity of this resin compared to PhFR and KLPhFR. In all SFWM/FMDmilled-reinforced hybrid composites (PhFR, PhGR, and KLPhFR matrices), the FMDmilled acted as additional reinforcement, increasing the impact strength of the composites when compared to those reinforced only with SFWM. The broad set of results regarding the reinforcements, synthesized resins, and their composites adds new knowledge to the area of phenolic-type thermoset composites reinforced by plant fibers. The materials prepared have potential for applications such as electrical insulators, non-structural parts of automobiles, aircraft, as well as in the naval area.
dc.formatapplication/pdf
dc.identifier.doi10.11606/T.75.2020.tde-19052020-104459
dc.identifier.urihttp://www.teses.usp.br/teses/disponiveis/75/75135/tde-19052020-104459/
dc.languagept
dc.rights.holderPinheiro, Francisca Gleyciara Cavalcante
dc.subjectcompósito
dc.subjectfibra do mesocarpo do dendê
dc.subjectlignina Kraft
dc.subjectmantas naturais
dc.subjectcomposite
dc.subjectKraft lignin
dc.subjectnatural woven mat
dc.subjectoil palm mesocarp fiber
dc.titleSíntese de termorrígidos fenólicos simultaneamente à formação de compósitos: fibras e mantas como reforço vegetal
dc.title.alternativeSynthesis of phenolic thermosetting with simultaneous composites formation: fibers and woven mats as vegetal reinforcement
dc.typeTese de Doutorado
usp.advisorFrollini, Elisabete
usp.date.defense2020-02-07
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