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

Incorporação da apatita na superfície da liga Ti30ta empregando tratamento alcalino associado à eletrofiação de fibras de PCL

Pós-graduação em Engenharia Mecânica - FEG

Estudo da modificação superficial de fibras de carbono por meio de tratamentos a plasma para o aumento da adesão na interface de compósitos fibra de carbono/PPS

Pós-graduação em Engenharia Mecânica - FEG

Estudo do comportamento reológico de sucos combinados de frutas vermelhas

The aim of this work was to evaluate the rheological behavior of combined juices of strawberry, blackberry and raspberry in two different temperatures of interest in industrial processes in the food industry, using rheological analyses on non-oscillatory regime and the Response Surface Methodology (RSM). The rheological data were fitted by the Casson model. All samples of combined juices of ref fruits showed a Newtonian behavior and the rheological parameters yield stress (Kc) and plastic viscosity of Casson (Koc) had a decrease in its values with the temperature increase. By the analysis of the ternary diagrams it is evident that the raspberry juice effectively contributed to the higher values of yield stress and plastic viscosity of Casson in both temperatures studied.

Fibras alimentares: efeito na farinha, reologia das massas, qualidade e taxa de envelhecimento de pães

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

Otimização do processo de soldagem por resistência elétrica em compósitos PEI/fibras contínuas para aplicações aeronáuticas

Pós-graduação em Engenharia Mecânica - FEG

Avaliação dos parâmetros tempo, corrente e pressão na soldagem por resistência elétrica de compósitos PEI/fibras contínuas: influência na resistência mecânica

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)

Efeito das fibras alimentares como substitutos de gordura em hambúrguer de carne bovina e paio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Temperaturas de armazenamento e uso de soluções de manutenção na pós-colheita de gérberas vermelhas

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Efeitos do treinamento aeróbio e de força sobre a área de secção transversal (AST) das fibras do músculo plantar de ratos

Recent research seeking to elucidate the possible effects of different types of physical training on the morphological adaptations of skeletal muscle. Although it is relatively easy to study the effects of exercise training in humans, such research becomes limited due to the invasive nature of the biopsies and the risk inherent in the use of human subjects. Thus, the application of animal models of training has been considered an appropriate strategy for the study of muscular adaptations in response to exercise. Objective: This study used a rodent model to determine the possible effects of aerobic and strength training on the CSA of fibers of the plantaris muscle. Methods: 24 male Wistar rats (80 to 120 days, 250 to 400 g) were randomly divided into 3 groups: aerobic training (TA, n = 8), strength training (ST, n = 8) and control (CO, n = 8). The animals in groups TA and TF were subjected to 8 weeks of training, while the animals of group C remained without any stimulus from start to finish the training period. At the end of the experiment, the animals were sacrificed and right plantar muscles dissected and removed. For morphological and morphometric analysis of muscle fibers was performed staining was performed H.E. Results: There was no significant difference in initial body weight between experimental groups. After 8 weeks of training, the TA group showed a significant reduction in final body weight, compared to CO and TF groups. With respect to the CSA of fibers of the plantaris muscle, no significant difference between the groups CO and TA. On the other hand, the strength training promoted a significant increase in AST of the group TF in compared with the groups CO and TA. Conclusion: Strength training used in this study promoted an increase in CSA of fibers of the plantaris muscle. On the other hand, animals submitted to aerobic training showed no changes in the CSA of the fibers, however, there was reduction in PC animals. The data strongly suggest the use of animal model of strength training used in this study as an appropriate strategy for studying the hypertrophic response of skeletal muscle.

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

Detecção e quantificação de corantes de importância ambiental empregando sensores químicos baseados em fibras ópticas e polímeros molecularmente impressos

Pós-graduação em Química - IQ

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)