Flexão e análise dinâmico-mecânica de compósitos 5HS e NCF com resina epóxi monocomponente produzidos por RTM

In order to study resin distribution and homogeneity of composite laminates manufactured by RTM, it was used CYCOM 890 monolithic toughened epoxy as a matrix with two different configurations of intermediated modulus (IM) carbon fibers: Satin Weave (5HS) and non crimp fabric (NCF). The injection parameters were defined based on Thermo Gravimetric Analysis (TG), Differential Scanning Calorimetry (DSC) and rheological analysis. After processing the material, the resin/fiber impregnation was studied using ultrasonic test, Thermo Gravimetric Analysis, Differential Scanning Calorimetry, Dynamic Mechanical Analysis (DMA) and flexural tests. Therefore, it was able to observe an internal residual stress during the cooling process in both laminates, higher in the composite using NCF fabric due to the lack of symmetry, although a good proportion of fiber/matrix has been verified by the lower values of flexural modulus deviation. The DMA enabled the visualization of glass transition and its association with the inter and intra molecular interaction and movement, in which the NCF composite presented better permeability due to the lowest temperature of glass transition, when compared to the Satin Weave composite

Estudo da superfície de fibras de carbono após tratamento de implantação iônica por imersão em plasma (3IP)

In this work, plasma immersion ion implantation (PIII) treatments of carbon fibers (CFs) were performed in order to induce modifications of chemical and physical properties of the CF surface aimed to improve the performance of thermoplastic composite. The samples to be treated were immersed in nitrogen or air glow discharge plasma and pulsed at −3.0 kV for 2.0, 5.0, 10.0, and 15.0 min. After PIII processing, the specimens were characterized by atomic force microscopy (AFM), scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). After CFs treatments, the CF/Polypropylene (PP) composites were produced by hot pressing method. Surface morphology of as-received CFs exhibited some scratches aligned along the fibers due to the fiber manufacturing process. After both treatments, these features became deeper, and also, a number of small particles nonuniformly distributed on the fiber surface can be observed. These particles are product of CF surface sputtering during the PIII treatment, which removes the epoxy layer that covers as-received samples. AFM analyses of CF samples treated with nitrogen depicted a large increase of the surface roughness (Rrms value approximately six times higher than that of the untreated sample). The increase of the roughness was also observed for samples treated by air PIII. Raman spectra of all samples presented the characteristic D- and G-bands at approximately 1355 and 1582 cm−1, respectively. Analysis of the surface chemical composition provided by the XPS showed that nitrogen and oxygen were incorporated onto the surface. The polar radicals formed on the surface lead to increasing of the CF surface energy. Both the modification of surface roughness and the surface oxidation contributed for the enhancement of CF adhesion to the polymeric matrix. These features were confirmed ... (Complete abstract click electronic access below)

Avaliação dos efeitos ambientais nas propriedades do compósito de poliamida 6,6/fibras de carbono

This graduation work done study of polyamide 6.6/composite carbon fibres, since its processing, characterization of the main properties. Besides the influence of temperature, UV radiation, salt spray and moisture on the mechanical and viscoelastic behavior. To achieve this goal, the first composite was processed from the heat compression molding using known variables of the process and using the empirical method to find the best value for other parameters. The method processing molding was chosen because it common in composites processing in order to evaluate the influence of crystallinity of the properties that influence the mechanical and viscoelastic behavior laminates. From the obtained laminate specimens were evaluated in weathering, such as: in hygrothermal chamber, UV, salt spray and thermal shock. In another step, the effect produced by these constraints were evaluated by optical microscopy, ultrasound, dynamic mechanical analysis and vibration tests. This project was conducted at the Department of Technology and Materials of UNESP in Guaratingueta, where all the equipment and techniques for the implementation of this project met available. After the tests proved the applicability of the composite polyamide 6.6/carbon fibers in aeronautical applications with resistance the main climatic influences

Anatomia comparada da casca de stryphnodendron polyphyllum mart. (fabaceae) em cerrado sensu stricto e mata de galeria

Pós-graduação em Ciência Florestal - FCA

Compósitos de nanocelulose / PHBV: manta microfibrilica por eletrofiação

Pós-graduação em Engenharia Mecânica - FEG

Otimização do processamento de partículas lead-free para aplicação em compósitos polímero/cerâmica com propriedades piezoelétrica e fotoluminescente

Pós-graduação em Química - IQ

Preparo e caracterização de compósitos polímero/cerâmica com potencial aplicação como sensor multifuncional

Pós-graduação em Química - IQ

Inspeção de materiais compósitos utilizando ondas acústicas guiadas

Pós-graduação em Engenharia Elétrica - FEIS

Obtenção e caracterização de compósitos de benzoxazina/fibra de carbono

Pós-graduação em Engenharia Mecânica - FEG

Predição de vida em fadiga de compósitos estruturais baseado em análises dinâmico-mecânicas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Eletrofiação de fibras de borracha natural com adição de polianilina

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Elaboração de pão com casca de abacate hass: valor nutricional e aceitabilidade

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Alterações nuricionais em casca e polpa de cenoura decorrentes de diferentes métodos de cozimento

The aim of this study was to verify the carrot cooking most suitable method to minimize nutrient losses. Carrot peel slices were subjected to pre cooking tests that were initiated with 0.5 min of duration and then increased in 0.5 min successively. The carrot pieces texture was monitored during the pre tests so all would havethe same texture independent of the type of cooking. The degree of softennes was evaluated by pressuring the pieces between the toes. The carrot pulp and pell were subjected to four types of heat treatment (pressure, immersion, microwave, and steam), after that they were pounded with a food processor and stored at -18 ºC. The nutritional analyses were as follow: The evalu determination of proteins, lipids, fibers, sugars reducers, total of ascorbic acid content and minerals (iron, calcium, zinc, magnesium, potassium, phosphorus, and calcium). The analyses were accomplished with fresh carrot and after cooking with the different methods. The peel of the carrot presented as amounts of proteins, lipids, fibers percentages, sugars reducers, total and ascorbic acid content equivalent to the pulp. In addition, the minerals content was superior in the peel in relation to the pulp, presenting respective percentages of 38,10%, 95,12%, 47,04%, 58,88%, 70,27% and 21,27%. There were nutrient losses in relation to the raw vegetable, when the carrot pieces were submitted to the different cooking methods. The methods of steaming and microwave had lower nutritional losses.

Características estruturais e físicas de material biodegradável produzido a base de zeína e fibras de milho e bananeira

Pós-graduação em Engenharia e Ciência de Alimentos - IBILCE

Obtenção e caracterização de nanocelulose a partir de fibras de Chorisia speciosa St. Hil

Natural fibers have been highlighted as a renewable material that can replace materials from oil and its derivatives. In this context, Brazil becomes the perfect setting because of the diversity of fibers found in its territory, such as sugarcane, sisal, rice, cotton, coconut, pineapple, among others. The paineiras (Chorisia speciosa St. Hil) are typically Brazilian trees, which produce paina as fruit. These fruits are still little studied as a source of lignocellulose by research groups. This project aimed obtaining and characterization of cellulose nanofibers from the fibers from the paina fibers. Obtaining nanocellulose is practically made through simplified chemical processes. First, was performed out pre-treatments to removal of waxes, lignin and hemicellulose. The first stage of pre-treatment was carried out by alkaline aqueous solution of sodium hydroxide (NaOH) at 5wt%, where the fibers were under constant agitation for 1h at 70°C. Through alkali treatment it was possible to remove most of the lignin, hemicellulose, waxes and extractives. After the alkaline treatment was done bleaching with an aqueous solution of sodium hydroxide (NaOH) to 4wt% and hydrogen peroxide (H2O2) to 24wt% 1:1 during 2h with constant stirring to 50 °C. Through bleaching was possibe to remove residual lignin, and got cellulose with 72% of crystallinity. Nanocellulose of paina fibers was extracted using different conditions of acid hydrolysis with sulfuric acid (H2SO4) to 50wt%. After acid hydrolysis, the suspensions were centrifuged during 30 min and dialyzed in water to remove excess acid until neutral pH (6-7). Then the suspensions were passed by ultrasonification in an ultrasound 20 kHz during 1h in an ice bath. Untreated, alkalinized and bleached fibers as well as cellulose nanoparticles were characterized by the techniques of thermogravimetry ... (Complete abastract click electronic access below)