Thermochemical and structural characterization of promising carnauba novel leaf fiber (Copernicia prunifera)

Abstract

The Copernicia prunifera palm tree, popularly known in Brazil as carnauba palm, is quite resistant and adapts very well to severe droughts. Its wood, leaves and fruits are widely used in various applications. In the present work, a thermochemical and structural characterization of the fibers extracted from the leaf of carnauba palm tree have been performed. Clean and dry fibers were subjected to characterization by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), lignocellulosic analysis and scanning electron microscopy (SEM). The thermogravimetric disclosed a moisture loss at 64.4 °C and degradation onset temperature at 267 °C. In DSC analysis an endothermic peak (208 °C) and two exothermic peaks (287 °C and 359 °C) were observed, probably correlated to the lignocellulosic constituents of the fibers. The FTIR spectra have shown bands referring to molecular vibrations of functional groups belonging to the constituents of NLF, such as cellulose, hemicellulose and lignin. Moreover, the diffraction pattern presented by the carnauba fibers (CF) attained a crystallinity index of 86.9% and microfibrillar angle (MFA) of 7.48°. The CF unveiled a moisture content of 7.2%. Furthermore, a chemical composition constituted by 4.8% extractives, 36.9% lignin, 40.9% hemicellulose and 20.2% cellulose has been achieved. In addition, SEM micrographs have shown that the CF possess superficial porosity along its length and an approximately elliptical cross section. Considering the abovementioned results, Carnauba fibers exhibits a high potential for engineering applications, its present properties are similar to other NLFs used as reinforcement for polymeric matrix composite.

Keywords

• Carnauba fiber
• Lignocellulosic
• Thermal stability
• Morphology
• Crystallinity