Papers by Author: Luiz Antonio Pessan

Abstract: Polyamide 6 (PA6)/Brazilian organoclay nanocomposites were obtained by melt intercalation and the structural and rheological properties were studied. The nanoclay was treated with quaternary ammonium salt (Cetremide) and characterized using infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results indicated the effective organophilization of nanoclay. The nanocomposites were obtained by melt intercalation using a twin screw corrotacional extruder in two steps. Firstly, a masterbatch of PA6 / nanoclay (1: 1) was prepared. In the second step the masterbatch was diluted in PA6 to obtain 3 and 5 wt% of nanoclay in the nanocomposites. The specimens were injection molded and analyzed using capillary rheometry, X-ray diffraction and transmission electron microscopy (TEM). The results of capillary rheometry showed that the presence of the organoclay in PA6 increased the viscosity of the systems. Structural characterization showed that the nanocomposites were predominant in exfoliated structure.

Abstract: Much attention is being given to developing nanocomposites with layered silicates, owing to the great need for advanced materials engineering and the fact that the pure polymers do not present the behavior or properties needed for certain applications within that context, the objective of this study was to influence of the molecular weight of polyamide 6 in obtaining nanocomposites with national organoclay. For this, the mixture of polyamide 6/ organoclay was processed in a twin screw extruder, and then was characterized by thermogravimetry (TG), X-ray diffraction (XRD) and heat deflection temperature (HDT). It was then possible to observe by XRD to obtain a structure exfoliated or partially exfoliated in the studied systems. For TG, it was found that the nanocomposites were stabilities higher than the pure polymer. And the values of HDT of systems were significantly higher than those of pure polyamide 6.

Abstract: Nanocomposites of PA6 / organoclay at different concentration were prepared via melt intercalation method using a corotating twin screw extruder. The composites were prepared with Brazilian clay that was treated with different modifiers based on quaternary ammonium salts to obtain three types of organoclays. After extrusion the mixtures were injection molded into specimens that were tested to obtain the properties of tensile strength, notched izod impact and heat deflection temperature. The structure and morphology of the nanocomposites were characterized by x-rays diffraction (XRD) and transmission electron microscopy (TEM). The results showed that the modifier “dodigen” which promoted the intermediate expansion of the bentonite clay within the three salts used for the modification of the clay affects more significantly the mechanical properties, HDT and morphology of the polyamide 6 due to the higher level of exfoliation observed in these systems compared to the others modifiers. The improvement of the properties was correlated to the level of exfoliation/intercalation obtained which depends on the process technique used, surface treatment of the Brazilian clays with organic salts and interaction between polymer and clay.