Obtenção e caracterização de compósitos de polihidróxibutirato (phb), reforçados com whiskers de celulose extraídos da folha do buriti (mauritia flexuosa l.)

Abstract

In recent years there has been a significant increase in the demand for materials obtained from renewable sources, in particular by natural fibers as reinforcement for polymer composites. Buriti (Mauritia flexuosa L.) is a palm native from Brazil, it is found mainly in the states of Pará, Maranhão and Piauí. The objective of this research was to obtain and characterize polyhydroxybutyrate (PHB) composites reinforced with cellulose nanocrystals and to study the effects of chemical treatments performed on buriti fibers. The fibers were obtained from the leaves of the buriti palm. These were treated in alkaline medium (1% and 5%) and with hydrogen peroxide in alkaline medium. To elaborate the composites the fibers were treated by acid hydrolysis at 60% at 45 º C for 60 minutes and the PHB was used as a matrix. The composites were consolidated by the casting method. Subsequently, the post-cure process was conducted at room temperature. The results of alkaline treatment effects on fibers show surface modifications such as wax removal and impurity. The FTIR assays showed the presence of absorption bands characteristic of lignocellulosic materials. The FTIR spectra in the composites showed chemical interaction between nanocrystals/ matrix. It indicated an increase in the thermal stability of the composites being the best result obtained with the W1% treatment, even though there was an increase of degradation temperature and transition of the polymer observed by the TG and DSC analyzes, respectively. The results obtained by DR-X showed that addition of nanocrystals decreased the intensity of the peaks of the matrix.