Biocomposites based on natural rubber (NR) reinforced with 45S5 BioglassÒ (BG) particles were obtained by casting/evaporation method in which NR was dissolved in chloroform and mixed with BG particles. Structural, mechanical, and thermal tests were performed on the biocomposites to evaluate the influence of BG particles on the properties of the NR matrix. Thermogravimetric tests (TG/DTG) of the biocomposites showed decomposition profiles similar to that of NR, and the main peak of the DTG curve was well defined in the temperature range 300-450°C, characteristic of the structural degradation of NR. The TG analysis also revealed that the thermal stability of the samples increases with the increasing quantity of BG in the biocomposite. DMA tests showed higher storage modulus (E 0) values for samples with larger amounts of BG; however, above the T g , the E 0 value tended to zero due to the increased mobility of the polymer chains. By analyzing tan d, the T g values were calculated to be-46 and-50°C for NR and the biocomposite samples, respectively. Mechanical testing demonstrated that the addition of BG to the biocomposite improved the mechanical properties of the samples. The samples became more rigid with the increasing quantity of BG, as demonstrated by decreasing deformation and the increasing elastic modulus (Y) and breaking strength of the samples. The BG particles positively affected the mechanical and thermal properties of the biocomposite, allowing its use in biomedical applications.
O desenvolvimento de metodologias para obtenção do oxido de grafeno a partir do grafite tem movimentando ainda boa parte das pesquisas., justamente pelos materiais em nanoescala possuírem grande potencial para aplicações como adsorventes no tratamento de efluentes contaminados com contaminantes emergentes, sendo está uma preocupação atual. Neste trabalho apresenta-se a síntese modificada via método Hummers de óxido de grafeno a partir do grafite em pó obtido comercialmente. A caracterização morfológica do material preparado ocorreu por meio da Difração de Raios X, FTIR e Espectrometria RAMAN, além de Microscopia Eletrônica de Varredura e de Transmissão. Os resultados evidenciam a formação de um nanomaterial com alto grau de oxidação e esfoliação, validando a rota de síntese utilizada evidenciando característica morfológicas do material como esperado na literatura.
In this study, spheres of poly (vinylidene fluoride)/clay were synthesized using an easy dripping method (also known as phase inversion). The spheres were characterized by scanning electron microscopy, X-ray diffraction, and thermal analysis. Finally, application tests were carried out using commercial cachaça, a popular alcoholic beverage in Brazil. The SEM images revealed that during the solvent exchange process for sphere formation, PVDF tends to form a three-layered structure with a low-porosity intermediate layer. However, the inclusion of clay was observed to reduce this layer and also widen the pores in the surface layer. The results of the batch adsorption tests showed that the composite with 30% clay content in relation to the mass of PVDF was the most effective among those tested, with the removal of 32.4% and 46.8% of the total copper present in the aqueous and ethanolic media, respectively. The adsorption of copper from cachaça in columns containing cut spheres resulted in adsorption indexes above 50% for samples with different copper concentrations. Such removal indices fit the samples within the current Brazilian legislation. Adsorption isotherm tests indicate that the data fit better to the BET model.
This work aimed to compare the characteristics of micro and nanofibers of the poly (vinylidene fluoride) - PVDF polymer obtained by the Solution Blow Spinning (SBS) method, and films with those produced by other techniques, such as: casting and hot pressing. Thermogravimetric analysis (TGA) revealed that the films are thermally stable up to a temperature of 420 ° C. X-ray diffractometry (XRD) indicated the presence of the crystalline phases α and β, the β phase being more evident for nanofibers and PVDF casting. The film obtained by SBS showed a greater contact angle, showing to be more hydrophobic. Strain tests showed that the nanofiber films showed a 72% rupture to rupture, about 1.7 and 3.1 times greater than those obtained by casting and hot pressing, respectively. There was also a decrease in the modulus of elasticity and the limit of tensile strength of nanofibers, compared to other films.
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