Preparação e caracterização de compósitos de PHB e mesocarpo de babaçu.

Abstract

Fully natural and biodegradable composites of commercial poly(3-hydroxybutyrate) (PHB) and fiber of the mesocarp of the fruit of the babacu palm were prepared with 5, 10, and 20% of vegetable fiber of two different granulometries, processed in an internal mixer. Matrix, load, and composites were characterized by melt flow index (MFI), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and optical microscopy (OM). The matrix (PHB) was found thermally unstable at processing temperatures. The load level and particle size significantly affected the melting and crystallization processes of PHB in the composites, in both its thermodynamic (melting temperature, crystallinity) and kinetic (crystallization rate) characteristics, suggesting that the mesocarp of babacu acted as a nucleating agent. Analysis of microphotographs showed that the load was well dispersed during processing. Particle size distribution was determined and the effect of loading level and granulometry was found to affect the mean particle size and breadth of the size distribution. It was found that the mixing process significantly decreases particle size, which becomes a function of the loading level.