Amanda Dantas de Oliveira

Efeito da sequência de mistura nas propriedades de blendas PA6/ABS compatibilizadas com o copolímero SMA

Blends of polyamide 6 (PA6) with acrylonitrile-butadiene-estyrene (ABS) were prepared in a twin-screw extruder, using the styrene-maleic anhydride (SMA) copolymer containing 7% of maleic anhydride as compatibilizer. The effects from three blending sequences on the microstructure and properties of the blends were investigated. The morphology and mechanical properties of the materials were characterized by transmission electron microscopy and tensile and impact tests. The results showed that the morphology and mechanical properties of ternary blends depend on the sequence of blend preparation. The blend prepared using the mixture of all components in a single-pass extrusion showed the more significant improvement in the material toughness. However, when the ABS and SMA were melt mixed together in a first extrusion step prior to incorporating PA6 in a second extrusion, the impact strength is lower than that of the blend without compatibilizer PA6/ABS and PA6 matrix. Evidence of chemical reactions between the compatibilizer SMA and PA6 was also obtained using a torque rheometer.

Influência da modificação da argila montmorilonita nas propriedades mecânicas, termo-mecânicas e morfológicas de nanocompósitos de blendas de poliamida 6/Acrilonitrila-EPDM-estireno

The effect of clay organophilization on mechanical, morphological and thermo-mechanical behavior of polyamide-6/acrylonitrile-EPDM (ethylene/propylene/diene elastomer)-styrene blends was studied. Three nanoclays were used for the preparation of nanocomposites: two commercial organically modified montmorillonites (Cloisite®30B and Cloisite® 20A) and an unmodified sodium montmorillonite (Cloisite®Na+). We used wide angle X-ray scattering, transmission electron microscopy and mechanical tests to evaluate the effect of clay modification on the morphology and mechanical properties of the nanocomposites. The thermo-mechanical properties were characterized using dynamic mechanical analysis and heat distortion temperature (HDT). The results show that the modification of clay affected simultaneously the degree of PA6 matrix reinforcement, dispersion of the clay lamellas in the blend and size of the dispersed phase AES. The incorporation of different nanoclays increase the elastic modulus of all the ternary nanocomposites compared to the neat blend. An increase in the toughness is obtained only for systems with Cloisite®Na+. A significant increment in the storages modulus and HDT was observed by the incorporation of Cloisite®30B in the PA6/AES blends.

Characterization of nanocomposites for hydrogen storage

The use of hydrogen as an energy carrier suitable to replace gasoline and other fossil fuels has been widely discussed as a way to sustainably fuel our civilization. However, hydrogen storage is a major barrier in the establishment of infrastructure for hydrogen technology. The incorporation of nanoparticles to the polymer matrix may be an alternative to obtain materials with promising properties for hydrogen storage. In this work, polyetherimide-based Nanocomposites were prepared using carbon nanotubes doped with sodium alanate (NaAlH4) as filler. The sodium alanate content was fixed at 30 wt% and were studied three carbon nanotubes concentrations: 5, 10 and 20 wt%. The nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Hydrogen sorption measurements.The use of hydrogen as an energy carrier suitable to replace gasoline and other fossil fuels has been widely discussed as a way to sustainably fuel our civilization. However, hydrogen storage is a major barrier in the establishment of infrastructure for hydrogen technology. The incorporation of nanoparticles to the polymer matrix may be an alternative to obtain materials with promising properties for hydrogen storage. In this work, polyetherimide-based Nanocomposites were prepared using carbon nanotubes doped with sodium alanate (NaAlH4) as filler. The sodium alanate content was fixed at 30 wt% and were studied three carbon nanotubes concentrations: 5, 10 and 20 wt%. The nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Hydrogen sorption measurements.

Polymer nanocomposites for hydrogen storage

Hydrogen is considered to be a clean, economical and safe renewable energy source that would be ideal to replace fossil fuels, because it is light, highly abundant and its oxidation product (water) is environmentally benign. However, hydrogen is easy to burn (the chemical energy per mass of hydrogen is at least three times larger than that of other chemical fuels), which has the risk of fire and explosion. The problems of transportation and storage restrict the application of hydrogen energy, which has become a key factor in the development and utilization of hydrogen energy. This gas adsorbs at solid surfaces depending on the applied pressure and temperature. For storage purposes in mobile applications, the adsorption of hydrogen has been studied mainly on carbon species, but light and reasonably cheap materials of high surface area should prove to be attractive as well. Porous material is a very promising hydrogen storage material, which stores the gas in the form of molecules at low temperatures and co...

Sulfonated poly(ether imide)/aluminium nanocomposites for hydrogen storage

Mobility is a socioeconomic reality that increases every year and it should be safe, economic and reasonably clean. Little energy needs to be expended to overcome potential energy changes, but a great deal is lost through friction and low-efficiency energy conversion. Hydrogen would be ideal as a synthetic fuel because it is lightweight, highly abundant and its oxidation product (water) is environmentally benign, but storage remains a problem. The clean way to produce hydrogen from water is to use sunlight in combination with photovoltaic cells and water electrolysis, although other forms of primary energy and other water-splitting processes are generally used. The chemical energy per mass of hydrogen is at least three times larger than that of other chemical fuels. Hydrogen adsorbs at solid surfaces depending on the applied pressure and temperature. The variation of attractive surface forces as a function of distance from the surface decides whether van der Waals-type weak physisorption of molecular hydr...