O trabalho visou realizar um estudo sobre o comportamento mecânico e de inflamabilidade de estruturas aeronáuticas de interior fabricadas a partir de compósitos reforçados por fibras naturais, especificamente compósitos de resina fenólica com fibras de algodão e de sisal, verificando assim, a possibilidade de substituir compósitos sintéticos. Num primeiro momento, análises experimentais foram executadas para determinar as propriedades mecânicas dos materiais. Em seguida, análises computacionais foram realizadas, empregando as propriedades referentes aos compósitos sintéticos e reforçados por fibras naturais, utilizando critérios de falha e tendo como referência o desempenho do compósito sintético para uma dada estrutura aeronáutica de interior. Além disso, foram efetuadas análises do seu comportamento quanto à inflamabilidade. A incorporação de retardantes de chama foi necessária para que os compósitos reforçados por fibras naturais atendessem aos requisitos de certificação aeronáutica. Após o processo de aditivação, observou-se um aumento do módulo de elasticidade à flexão (55% para o compósito de algodão, 16% para o compósito de sisal) e a diminuição da tensão de ruptura à flexão dos compósitos reforçados por fibras naturais analisados (45% para o compósito de algodão, 55% para o compósito de sisal). No entanto, com o aumento da espessura da estrutura aeronáutica adotada (5,2% para o compósito de algodão, 10,7% para o compósito de sisal), conclui-se que a substituição do compósito sintético pelo natural seria viável. Isto acarretaria em um aumento de massa em 6,2%, caso a estrutura fosse fabricada em compósito reforçado por fibra de sisal. Finalmente, constatou-se que a fração mássica de aditivo utilizada tem grande potencial de otimização e, que a eficiência dos compósitos reforçados por fibras naturais ainda pode ser melhorada. / This dissertation has aimed to study the mechanical behavior and the flammability of aeronautical interior structures manufactured from composites reinforced by natural fibers, specifically phenolic resin and cotton and sisal fibers composites, verifying the possibility of synthetic composites replacement. Firstly, experimental analyses were performed to determine the mechanical properties of the materials. Then, computational analyses were carried out, using properties of synthetic composites and composites reinforced by natural fibers. Also, failure criteria were applied, considering the synthetic composite performance of an interior aeronautical structure as reference. Furthermore, the behavior regarding flammability was analyzed. The addition of flame retardants was necessary for the composites reinforced by natural fibers in order to attend the aeronautical certification requirements. After the addition of flame retardants, an increase in the flexural modulus of elasticity (55% for the cotton composite, 16% for the sisal composite) and a decrease in the flexural stress at break (45% for the cotton composite, 55% for the sisal composite) were observed. However, with an increase of the thickness of the aeronautical structure (5.2% for the cotton composite, 10.7% for the sisal composite), it was concluded that the replacement would be feasible, which would lead to a increase of the mass equal 6.2% for the sisal fiber composite. Finally, it was evidenced that the used flame retardant mass fraction has a great potential for optimization and that the natural composites efficiency can be improved.

"This dissertation documents two interrelated studies that were conducted to more fundamentally understand the scalability of flame heat flux. The first study used an applied heat flux in the bench scale horizontal orientation which simulates a large scale flame heat flux. The second study used enhanced ambient oxygen to actually increase the bench scale flame heat flux itself. Understanding the scalability of flame heat flux more fully will allow better ignition and combustion models to be developed as well as improved test methods. The key aspect of the first study was the use of real scale applied heat flux up to 200 kW/m2. An unexpected non-linear trend is observed in the typical plotting methods currently used in fire protection engineering for ignition and mass loss flux data for several materials tested. This non-linearity is a true material response. This study shows that viewing ignition as an inert material process is inaccurate at predicting the surface temperature at higher heat fluxes and suggests that decomposition kinetics at the surface and possibly even in-depth may need to be included in an analysis of the process of ignition. This study also shows that viewing burning strictly as a surface process where the decomposition kinetics is lumped into the heat of gasification may be inaccurate and the energy balance is too simplified to represent the physics occurring. The key aspect of the second study was direct experimental measurements of flame heat flux back to the burning surface for 20.9 to 40 % ambient oxygen concentrations. The total flame heat flux in enhanced ambient oxygen does not simulate large scale flame heat flux in the horizontal orientation. The vertical orientation shows that enhanced ambient oxygen increases the flame heat flux more significantly and also increases the measured flame spread velocity."

Orientador: Celso Eduardo Tuna / Resumo: Com a criação de combustíveis alternativos para a redução de emissões de CO2 no setor aeronáutico, torna-se necessária a determinação de suas propriedades de segurança e, entre elas destacam-se os limites de inflamabilidade. O combustível alternativo aeronáutico, que é utilizado neste trabalho, é o farnesano, fabricado a partir da cana de açúcar, por um processo que transforma açúcar em hidrocarboneto, pela empresa Amyris, localizada em São Paulo, Brasil. O objetivo dessa dissertação é determinar experimentalmente os limites de inflamabilidade, inferior (LII) e superior (LSI) do farnesano, QAV e misturas de 10% (F10) e 50 % (F50) em massa de farnesano com o QAV a pressões reduzidas em ar. Utiliza-se uma bancada experimental, que segue a norma americana ASTM E681, para a determinação dos limites de inflamabilidade, em que se utiliza o critério visual de propagação de chama e um recipiente de vidro borosilicatado de 20,716 L. Primeiramente são determinados os limites de inflamabilidade dos combustíveis para a pressão de 101,3 kPa em temperaturas entre 140 e 220°C, comparando-se os resultados com os valores teóricos disponíveis na literatura para a validação do procedimento experimental. Em segundo lugar, são determinados os limites de inflamabilidade das amostras a pressões reduzidas como 80, 60, 40 e 20 kPa em temperaturas entre 140 e 200°C. Foram realizados, no total 636 testes para determinação dos limites de inflamabilidade, sendo a duração média, para cada teste de 20 minu... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The creation of alternative fuels to reduce CO2 emissions from the aeronautical sector needs determination of their safety properties, among which are flammability limits. farnesane is the alternative aviation fuel used in here, which has been produced from sugar cane through a conversion process known as direct sugar to hydrocarbon (DSHC) created by a company called Amyris, which is located in São Paulo, Brazil. Thereby, it is aimed to experimentally determine the flammability limits, lower (LFL) and upper (UFL) of farnesane, Jet fuel and mixtures of 10% (F10) and 50% (F50) in mass of farnesane at reduced pressures with air. For such a purpose, an experimental bench was built in accordance with American standard ASTM E681 to determine the lower flammability limits, in which flame propagation was analyzed visually through a 20.716 L borosilicate glass flask. The Flammability Limits of the fuels were initially determined at a pressure of 101.3 kPa and temperatures ranging between 140 and 220 ° C, whose results were compared with theoretical values found in literature in order to validate the experimental procedure. Afterwards, the Flammability Limits of samples were determined at reduced pressures, i.e. 80, 60, 40 and 20 kPa, and temperatures ranging between 140 and 200 ° C. 636 tests were performed altogether, the average time of each test was 20 minutes. Finally, prediction equations of flammability limits, were presented as a function of temperature / Mestre

No description available.

Traditional fluorosilicones contain a siloxane backbone and pendant fluorinated group leading to low temperature ductility and excellent thermal stability. However, acidic or basic catalysts can reduce the thermal stability from a potential 350 °C to 150 °C. The predominant decomposition mechanism is through chain scission and it is hypothesized that preventing this will result in polymers with higher thermal stability. Three approaches were taken to prevent chain scission. First, a series of hybrid fluorosilicones based on (trifluorovinyl)benzene were synthesized through condensation polymerization with initial decomposition temperatures of approximately 240 °C. These were compared to similar aromatic polyethers and removal of the ether oxygen lowered the initial decomposition temperature by approximately 190 °C demonstrating the importance of this oxygen to the stability of polyethers. Second, reverse fluorosilicone (fluorinated backbone and pendant siloxane) terpolymers of chlorotrifluoroethylene (CTFE), vinyl acetate (VAc) and methacryloxypropyl-terminated polydimethylsiloxane (PDMSMA) were synthesized in supercritical CO2 (scCO2) or by emulsion polymerization. Chain scission was prevented as initial decomposition occurred between 231 and 278 °C. In both the emulsion and scCO2 cases, VAc was essential in facilitating cross-propagation between CTFE and PDMSMA and the branching was similar suggesting polymerization media does not affect polymer structure. Emulsion-based polymers had higher molar masses and thermal stability whereas comparable scCO2 polymers had higher yields and incorporated more PDMSMA. Third, a series of homo-, co-, and terpolymers of CTFE, VAc and methacryloxypropyl-terminated silsesquioxane (POSSMA) were synthesized representing the first synthesis of POSSMA containing polymers in scCO2 and demonstrating reverse fluorosilicones can be synthesized without VAc. Chain scission was prevented as initial decomposition occurred from 244 to 296 °C with thermal stability increasing with CTFE content to a limit. Decomposition of the polymers was examined and mechanism elucidated. In air, the copolymers give 40 to 47 wt% char since the silsesquioxane oxidizes to SiO2 while in N2, no residue is seen. In contrast, the terpolymers give a carbonaceous residue of approximately 20 wt% in N2. The flammability and surface properties of the polymers were examined with the terpolymers having flammability similar to p(CTFE) and surface properties comparable to p(POSSMA) giving a low-flammability, hydrophobic polymer.

Traditional fluorosilicones contain a siloxane backbone and pendant fluorinated group leading to low temperature ductility and excellent thermal stability. However, acidic or basic catalysts can reduce the thermal stability from a potential 350 °C to 150 °C. The predominant decomposition mechanism is through chain scission and it is hypothesized that preventing this will result in polymers with higher thermal stability. Three approaches were taken to prevent chain scission. First, a series of hybrid fluorosilicones based on (trifluorovinyl)benzene were synthesized through condensation polymerization with initial decomposition temperatures of approximately 240 °C. These were compared to similar aromatic polyethers and removal of the ether oxygen lowered the initial decomposition temperature by approximately 190 °C demonstrating the importance of this oxygen to the stability of polyethers. Second, reverse fluorosilicone (fluorinated backbone and pendant siloxane) terpolymers of chlorotrifluoroethylene (CTFE), vinyl acetate (VAc) and methacryloxypropyl-terminated polydimethylsiloxane (PDMSMA) were synthesized in supercritical CO2 (scCO2) or by emulsion polymerization. Chain scission was prevented as initial decomposition occurred between 231 and 278 °C. In both the emulsion and scCO2 cases, VAc was essential in facilitating cross-propagation between CTFE and PDMSMA and the branching was similar suggesting polymerization media does not affect polymer structure. Emulsion-based polymers had higher molar masses and thermal stability whereas comparable scCO2 polymers had higher yields and incorporated more PDMSMA. Third, a series of homo-, co-, and terpolymers of CTFE, VAc and methacryloxypropyl-terminated silsesquioxane (POSSMA) were synthesized representing the first synthesis of POSSMA containing polymers in scCO2 and demonstrating reverse fluorosilicones can be synthesized without VAc. Chain scission was prevented as initial decomposition occurred from 244 to 296 °C with thermal stability increasing with CTFE content to a limit. Decomposition of the polymers was examined and mechanism elucidated. In air, the copolymers give 40 to 47 wt% char since the silsesquioxane oxidizes to SiO2 while in N2, no residue is seen. In contrast, the terpolymers give a carbonaceous residue of approximately 20 wt% in N2. The flammability and surface properties of the polymers were examined with the terpolymers having flammability similar to p(CTFE) and surface properties comparable to p(POSSMA) giving a low-flammability, hydrophobic polymer.

Metallic materials and oxygen can be a volatile combination when accompanied by ignition mechanisms. Once ignited, metallic materials can readily burn in high pressure oxygen atmospheres, releasing an enormous amount of energy and potentially destroying equipment, space missions and resulting in the loss of life. The potential losses associated with these fires led to research into the conditions under which metal fires propagate. Several organisations, including the American Society for Testing and Materials (ASTM) and the International Organisation for Standardisation (ISO), have published recommended standard test practices with which to assess the relative flammability of metallic materials. These promoted ignition tests, so called because samples are ignited with an overwhelming source of energy, are typically used to examine two important parameters as an indication of a metallic material's flammability: Threshold Pressure (TP) and the Regression Rate of the Melting Interface (RRMI). A material's TP is the minimum pressure at which it burns, therefore, TPs of different materials can be compared to assess which materials are most suited for a range of high pressure applications. The RRMI is a useful measure for ranking materials, particularly if they have the same TP, but can be used as a ranking method irrespective of TP. In addition, it is a crucial parameter to aid in understanding the complex burning process and is one of the few experimental parameters that can be measured. Promoted ignition test standards specify a standard sample geometry to use when performing the test, typically a 3.2 mm diameter cylindrical rod. The recent addition of a 3.2 × 3.2 mm square rod as an optional standard sample geometry raises the issue of how the geometry of a sample affects its flammability. Promoted ignition test results for standard geometries are often applied to assess the flammability risk for the complex geometries of real components within oxygen systems, including regulators, valves, piping etc. Literature shows that sample geometry has a significant effect on material rankings when rankings are based on testing of standard geometries, for example, cylindrical rods, compared to non-standard geometries, for example, sintered filters and meshes. In addition, the RRMI has been shown to be dependent on a sample's cross-sectional area (XA). However, it remains unclear, from a simple heat transfer analysis, why the RRMI is dependent on XA or how the shape of a sample affects its melting rate. These questions are particularly relevant since understanding how sample geometry affects burning contributes to two important research goals: to be able to accurately model and predict the flammability risk of a metallic component without the need for physical testing, and to understand the effects of different sample geometries on their relative flammabilities within the standard tests used. Promoted ignition tests were conducted on iron rods with cylindrical, rectangular and triangular cross sections for a range of XAs. Their RRMIs were measured and analysed using a statistical approach which allowed differences in RRMI to be quantitatively assessed. Statistically significant differences in RRMI were measured for rods with the same XA but of different shape. Furthermore, the magnitude of the difference was dependent on XA. Triangular rods had the fastest RRMIs, followed by rectangular rods and then cylindrical rods. Differences in RRMI based on rod shape are due to heat transfer effects and the dynamic motion of the attached molten mass during the drop cycle. The corners of the rectangular and triangular rods melt faster due to their locally higher Surface Area to Volume ratio (SA/V). This dynamic effect increases the area of contact between the molten mass and the solid rod (solid liquid interface (SLI)) which facilitates increased heat transfer to the rod resulting in a faster RRMI. This finding highlights the importance of the SLI in the heat transfer process. Although the SLI is largely dependent on the XA, the shape of the rod causes subtle changes to the size of the SLI and thus affects heat transfer, burning and observed RRMI. The relationship between rod diameter, test pressure and Extent of Reaction (ER), the proportion of metal that reacts (oxidises) whilst attached to the burning rod, was investigated. During promoted ignition testing of iron rods of varying diameter the detached drops were rapidly quenched by immersion in a water bath. Microanalysis techniques were used to qualitatively assess the ER as a function of pressure and rod diameter. It was found that the pressure dramatically affects ER. High pressure tests resulted in a slag mass consisting of oxide, with no unreacted iron, whereas low pressure tests resulted in a significant fraction of unreacted iron within the slag. This indicates that the ER contributes directly to the observed increase in RRMI with increasing test pressure. At high pressures the ER is not affected by rod diameter, since all available liquid metal reacted, but at low pressures ER is a function of rod diameter, ER decreases as XA increases. This thesis also investigates the analysis of promoted ignition test data through suitable statistical methods. Logistic regression is identified as an appropriate method for modelling binary burn/no-burn test data. The relationship between the reaction probability, defined as the probability that a sample will undergo sustained burning, and pressure, is evaluated for two different data sets. The fits of the logistic regression models are assessed and found to model the available data well. The logistic regression method is contrasted with the confidence levels associated with binary data based on the Bernoulli distribution. It is concluded that a modelling approach is beneficial in providing an overall understanding of the transition between pressures where no burning occurs and pressures where burning is expected.

Submitted by EDWIN SANTIAGO RIOS ESCALANTE null (esre_2808@hotmail.com) on 2016-09-12T20:28:02Z No. of bitstreams: 1 template-feg-2016-VERSÃO FINAL.pdf: 3419531 bytes, checksum: 2e6eca3a01fecef269a3334812ba75d2 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-09-14T19:40:34Z (GMT) No. of bitstreams: 1 escalante_esr_me_guara.pdf: 3419531 bytes, checksum: 2e6eca3a01fecef269a3334812ba75d2 (MD5) / Made available in DSpace on 2016-09-14T19:40:34Z (GMT). No. of bitstreams: 1 escalante_esr_me_guara.pdf: 3419531 bytes, checksum: 2e6eca3a01fecef269a3334812ba75d2 (MD5) Previous issue date: 2016-07-12 / Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP) / Os limites superior e inferior de inflamabilidade são as concentrações máximas e mínimas de um combustível no ar, respectivamente, na qual uma chama pode se propagar, eles são considerados ferramentas chaves na predição do fogo, avaliando a possibilidade de explosão e projeto de sistemas de proteção. Existe interesse em encontrar os limites de inflamabilidade do etanol misturado com um diluente para pressões reduzidas para o futuro uso desse biocombustível em aplicações aeronáuticas tendo em conta a altitude típica de um avião comercial (<40 000 ft.). Neste trabalho foi desenvolvido experimentalmente a inflamabilidade do combustível líquido: Etanol hidratado e utilizou-se como gás diluente o nitrogênio. A bancada experimental usada, consiste de um recipiente esférico de 20 litros como câmara de aquecimento, uma fonte de ignição por faísca localizada na parte central da câmara. O líquido foi injetado com uma seringa de precisão de 1ml de volume para logo se evaporar no interior da câmara, o nitrogênio e ar foram injetados usando pressões parciais. O método para medir a inflamabilidade foi baseado na ignição elétrica e observação visual da propagação da chama conforme norma ASTM E-681. Primeiro os limites superior e inferior de inflamabilidade foram determinados para elevada temperatura (60℃) e pressão ambiente (101,325 kPa) para comparar os resultados com os dados publicados na literatura científica. Depois procedeu-se trabalhar com pressões reduzidas (80, 60, 40 e 20 kPa) para essa mesma temperatura, finalmente foram realizados testes para uma temperatura maior (110℃) para avaliar a influência da temperatura sobre os limites de inflamabilidade de misturas etanol-ar-diluente, os resultados foram plotados como função da relação e adição de nitrogênio e esses gráficos seguem a mesma tendência de trabalhos publicados na literatura científica. / The upper and lower limits of flammability are the maximum and minimum concentrations of a fuel in the air, respectively, in which the flame can spread; they are considered key tools for predicting fire, evaluating the possibility of explosion and protection system design. There is interest in finding the flammability limits of ethanol mixed with a diluent to reduced pressure for future use this biofuel in aeronautical applications having regard the typical height of a commercial aircraft (<40, 000 ft.). In this experimental work was carried flammability of the liquid fuel: Ethanol hydrate and used as a diluent gas nitrogen. The experimental apparatus consists of a 20 liters spherical vessel as heating chamber, a spark ignition source located in the central part of the chamber. The liquid was injected with a 1 ml syringe precision volume immediately evaporates in the chamber; nitrogen and air were injected using partial pressures. The method for flammability measuring was based in both visual observation electric ignition and flame propagation as defined by ASTM E-681. First, the upper and lower flammability limits were determined to a high temperature (60 ℃) and ambient pressure (101.325 kPa) to compare the results with data published in the scientific literature. After, we proceeded to work at reduced pressures (80, 60, 40 and 20 kPa) to same temperature. Finally, tests were carried out for a higher temperature (110 ℃) to evaluate the influence of temperature on the flammability limits ethanol-air-diluent mixtures, the results were plotted as a function of the relationship and adding nitrogen and these graphs follow the same trend of papers published in scientific literature.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-09-26T15:00:31Z No. of bitstreams: 1 RENATA BARBOSA - TESE (PPGEP) 2009.pdf: 13292645 bytes, checksum: e1d1eb846f17881cd108a8bad8f924ec (MD5) / Made available in DSpace on 2018-09-26T15:00:31Z (GMT). No. of bitstreams: 1 RENATA BARBOSA - TESE (PPGEP) 2009.pdf: 13292645 bytes, checksum: e1d1eb846f17881cd108a8bad8f924ec (MD5) Previous issue date: 2009-06-19 / Nanocompósitos de PEAD/argila bentonítica modificada e sem modificação foram preparados por meio do processo de intercalação por fusão. Realizou-se, previamente um estudo sistemático com quatro sais quaternários de amônio e em três tipos de argilas bentoníticas. Em seguida, fez-se a escolha de um sal quaternário de amônio e de uma argila bentonítica para dar continuidade ao trabalho. A argila escolhida foi organofilizada usando-se diferentes percentuais de sal quaternário de amônio 100%, 125% e 150% baseados na capacidade de troca de cátions (CTC) da argila. Ficou evidente por difração de raios- X (DRX) que os sais foram incorporados à estrutura da argila confirmando assim sua organofilização. Em princípio, todos os sais poderão ser usados para a organofilização da argila e, consequentemente nos sistemas de nanocompósitos PEAD/argila organofílica. Porém, foi verificado que o tipo de ânion presente pode influenciar a estabilidade térmica do sal quaternário de amônio. Os nanocompósitos foram preparados em uma extrusora de rosca dupla contrarrotacional e, em seguida, corpos de prova foram moldados por injeção. Para a avaliação da inflamabilidade dos sistemas foi utilizado o teste de queima na posição horizontal segundo a norma (UL-94HB) e o método do Calorímetro de Cone. O comportamento térmico dos nanocompósitos foi avaliado por temperatura de deflexão térmica (HDT) e termogravimetria (TG). As técnicas de DRX e microscopia eletrônica de transmissão (MET) foram utilizadas para caracterizar a morfologia e analisar o grau de expansão das argilas preparadas bem como o grau de esfoliação dos nanocompósitos. As propriedades mecânicas de tração e impacto também foram analisadas. Para efeito de comparação, determinadas composições foram extrudadas utilizando-se duas configurações de roscas da extrusora ZSK-30 corrotacional, com objetivos de variar as condições de processo e melhorar as propriedades dos nanocompósitos obtidos. Observou-se que o percentual de sal de amônio e o tipo de compatibilizante polar influenciam nas propriedades finais dos nanocompósitos. / High Density Polyethylene (HDPE) nanocomposites containing unmodified and modified bentonite clay were prepared by melt intercalation technique. Initially, four quaternary ammonium salts and three types of bentonitic clays were studied. Afterwards, one type of salt and one type of clay were chosen for the study. The clay was organophilized using 100,125 and 150wt% of quaternary ammonium salt based on cationic exchange capacity (CEC) of the clay. It was evident from the X-ray diffraction (XRD) that the salts were incorporated into the clay structure confirming its organophilization. In general, all salts may be used for clay organophilization and hence, on HDPE/Organophilic clay nanocomposites. However, it was verified that the type of anion present may influence the thermal stability of the quaternary ammonium salt. The nanocomposites were prepared in a counter-rotating twin screw extruder and the samples were prepared by injection molding. For the evaluation of the flammability, horizontal burn (UL-94HB) and cone calorimeter methods were used. The thermal behavior of the nanocomposites was analyzed by Heat Distortion Temperature (HDT) and Thermogravimetry (TG). XRD and Transmission Electron Microscopy (MET) techniques were used to characterize the morphology and analyze the degree of expansion of the prepared clays, and also the degree of exfoliation of the nanocomposites. Mechanical properties (Tensile and Impact strength) were also analyzed. Some compositions were extruded using two screw configurations of ZSK-30 co-rotacional extruder with the aim of improving the properties of the nanocomposites obtained by varying the processing conditions. It was observed that the percentage of the ammonium salt and the type of polar compatibilizer influence the final properties of the nanocomposites.

O trabalho visou realizar um estudo sobre o comportamento mecânico e de inflamabilidade de estruturas aeronáuticas de interior fabricadas a partir de compósitos reforçados por fibras naturais, especificamente compósitos de resina fenólica com fibras de algodão e de sisal, verificando assim, a possibilidade de substituir compósitos sintéticos. Num primeiro momento, análises experimentais foram executadas para determinar as propriedades mecânicas dos materiais. Em seguida, análises computacionais foram realizadas, empregando as propriedades referentes aos compósitos sintéticos e reforçados por fibras naturais, utilizando critérios de falha e tendo como referência o desempenho do compósito sintético para uma dada estrutura aeronáutica de interior. Além disso, foram efetuadas análises do seu comportamento quanto à inflamabilidade. A incorporação de retardantes de chama foi necessária para que os compósitos reforçados por fibras naturais atendessem aos requisitos de certificação aeronáutica. Após o processo de aditivação, observou-se um aumento do módulo de elasticidade à flexão (55% para o compósito de algodão, 16% para o compósito de sisal) e a diminuição da tensão de ruptura à flexão dos compósitos reforçados por fibras naturais analisados (45% para o compósito de algodão, 55% para o compósito de sisal). No entanto, com o aumento da espessura da estrutura aeronáutica adotada (5,2% para o compósito de algodão, 10,7% para o compósito de sisal), conclui-se que a substituição do compósito sintético pelo natural seria viável. Isto acarretaria em um aumento de massa em 6,2%, caso a estrutura fosse fabricada em compósito reforçado por fibra de sisal. Finalmente, constatou-se que a fração mássica de aditivo utilizada tem grande potencial de otimização e, que a eficiência dos compósitos reforçados por fibras naturais ainda pode ser melhorada. / This dissertation has aimed to study the mechanical behavior and the flammability of aeronautical interior structures manufactured from composites reinforced by natural fibers, specifically phenolic resin and cotton and sisal fibers composites, verifying the possibility of synthetic composites replacement. Firstly, experimental analyses were performed to determine the mechanical properties of the materials. Then, computational analyses were carried out, using properties of synthetic composites and composites reinforced by natural fibers. Also, failure criteria were applied, considering the synthetic composite performance of an interior aeronautical structure as reference. Furthermore, the behavior regarding flammability was analyzed. The addition of flame retardants was necessary for the composites reinforced by natural fibers in order to attend the aeronautical certification requirements. After the addition of flame retardants, an increase in the flexural modulus of elasticity (55% for the cotton composite, 16% for the sisal composite) and a decrease in the flexural stress at break (45% for the cotton composite, 55% for the sisal composite) were observed. However, with an increase of the thickness of the aeronautical structure (5.2% for the cotton composite, 10.7% for the sisal composite), it was concluded that the replacement would be feasible, which would lead to a increase of the mass equal 6.2% for the sisal fiber composite. Finally, it was evidenced that the used flame retardant mass fraction has a great potential for optimization and that the natural composites efficiency can be improved.