RESUMOForam preparados compósitos PHB/TiO 2 e PHB/ZnO num misturador interno de laboratório, a cristalização foi investigada por calorimetria exploratória diferencial (DSC), com taxas de aquecimento e resfriamento entre 5 e 30 °C/min e a superfície de fratura de seletas composições analisada por microscopia eletrônica de varredura (MEV). Através das imagens de MEV foi observado que as nanopartículas de ZnO e TiO 2 estão bem dispersas na matriz de PHB. Por DSC, observou-se que a adição de TiO 2 e ZnO modificou a temperatura e taxa de cristalização do PHB, sem afetar significativamente a cristalinidade total. Em geral, a adição da carga TiO 2 promoveu alterações mais significativas na matriz de PHB, comportando-se como um agente nucleante. Palavras-chave: PHB, cristalização, TiO 2 , ZnO, DSC. ABSTRACTPHB/TiO 2 and PHB/ZnO compounds were prepared in a laboratory internal mixer. Crystallization was investigated by differential scanning calorimetry (DSC) with heating and cooling rates ranging from 5 to 30 ºC/min. Fractured surface of selected samples was analysed by scanning electron microscopy (SEM). From the SEM images, it was observed that ZnO and TiO 2 nanoparticles were properly dispersed in the PHB matrix. DSC studies revealed that the addition of TiO 2 and ZnO changed the temperature and crystallization rate but did not affect the total crystallinity significantly. In general, TiO 2 behaved as nucleating agent greatly influencing the PHB crystallization.

This work presents the preparation of blended (HDPE/UHMWPE) nanocomposites with graphite nanosheets (GNS) by melt mixing (differing compositions) in an internal mixer. After graphite flake treatments to obtain GNS; HDPE/UHMWPE blends are produced using a Haake internal mixer with further compression molding. The blends were prepared as mixes of 0, 10, 20, and 30 wt% of UHMWPE in HDPE. The blend with the best mechanical and thermal properties is chosen to prepare the nanocomposites. The nanocomposites are produced from the 10 wt% UHMWPE in HDPE blend, with 0.5 and 1.0 wt% GNS using the same method as used for obtaining the blends. The functionalized graphite FTIR spectrum revealed functionalization with silane. However, after the ultrasonic bath these groups left the graphitic structure, and as shown by the diffractogram (XRD) and SEM images, good exfoliation continued. The nanocomposite blend with 10 wt% UHMWPE presented higher tensile strength values than pure UHMWPE, and the nanocomposite blend with the lower GNS percentage (0.5 wt%) presented the highest tensile strength. However the nanocomposite with 1.0 wt% GNS presented an increase in crystallization temperature.