Desenvolvimento de bionanocompósitos de biopolietileno/argila vermiculita organofílica.

Abstract

Polymers derived from oil have caused environmental impact due to its inappropriate disposal. An alternative is the use of biopolymers like biopolyethylene (bioPE). Polymer/clay nanocomposites have attracted great interest of researchers around the world since they present good thermal and barrier properties, flame retardance, strength and high modulus. In this work BioPE/vermiculite organophilic clay bionanocomposites were developed using the melt intercalation method. The effect of the vermiculite clay content on the mechanical and rheological properties was evaluated. The amount of the surfactant used to organically modify the vermiculite clay was based on the Cation Exchange Capacity (CEC) of the clay. The bionanocomposites were prepared by extrusion followed by injection molding. The vermiculite clay was characterized by X-Ray Diffraction (XRD), Infrared Spectroscopy (FTIR), X-Ray Fluorescence (XRF), and particle size anatyses by laser diffraction (AG) while the bionanocomposites were characterized by XRD, FTIR, Scanning Electron Microscopy (SEM), thermal and mechanical properties melt flow índex (MFI) and rheological measurements under low and high shear rates, and oscillatory shear flow. XRD and FTIR results showed that the surfactant was incorporated to the vermiculite structure confirming its organophilization. XRF result indicated a possible substitution of vermiculite exchangeable cátions with the ions present in the surfactant. The AG analysis evidenced that the organophilization process led to a decrease in the particles average size and doubled the clay fraction below 2\im. The increase in the organophilic vermiculite clay content favored the increase in the modulus and the decrease in the MFI, impact strength, and hardness, while the tensile strength remained almost unchanged. The rheological measurements indicated that the viscosity increased with the clay content. This variation was observed at low frequencies, where the storage modulus was higher when compared to pure BHDPE for ali compositions studied. For the rheological measurements at higher frequencies, the viscosity decreased with the increase in the clay content.