Efeito das condições de processamento nas propriedades de nanocompósitos PBAT/argilas organofílicas.

Abstract

In this work, PBAT/organoclay nanocomposites with 2.5; 5,0 e 7,5% filler content were prepared by two routes: (I) direct mixing in an internal mixer, operating at 180°C for 15 minutes at speeds of 60, 120 and 180 rpm, and (II) preparation of a masterbatch (1:1 PBAT/organophilic clay) processed at 180°C, 120 rpm for 15 minutes followed by dilution with the matrix in a double screw corrotational extruder to the desired concentrations. Nanocomposites PBAT/C20A organoclay prepared by route (I), were analyzed by torque rheometry and the formulations thus processed were ground, injected and characterized by X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetry (TG) and parallel plate rheometry. PBAT/organoclay masterbatches containing three different organophilic clays (C10A, C20A and C30B) were prepared by route (II). The masterbatches were ground and extruded in co-rotational twin-screw extruder and matrix diluted to the desired concentrations. The neat matrix was processed under the same conditions. The systems obtained by this route were characterized by XRD, DSC, TG, Dynamic-Mechanical Analysis (DMA), Transmission Electron Microscopy (TEM) and Parallel Plate Rheometry. Results show the processing condition in the internal mixer that led to nanocomposites with higher degree of mixing and better thermal and rheological properties was at 120 rpm and that, although both routes generated nanocomposites with intercalated structures, route II led to structures with greater basal interplanar distance and a slight increase in the degree of crystallinity. Nanocomposites prepared by route II displayed a slight increase in thermal stability which increased with clay content. The elastic modulus, obtained by DMA, varied with clay concentration and was independent of the type of organophilic clay. The glass transition temperature (Tg) is also independent of clay content and identity.