Physico and Chemical Characterization of NFC and CNC Structure

Abstract

Aims: Investigate fully physical, chemical and morphological structure of the NFC and CNC produced in an industrial pilot plant to develop better applications for nanocelluloses. Methodology: Chemical, physical and morphological structure characterization was performed through high-tech devices such as elemental analysis, carbohydrate content, metal content, electronic and atomic force microscopy, X-ray, FTIR, thermogravimetric analysis, zeta potential and fungal biodegradation. Results: CNC presented a higher sulfation (0.9 %) than the NFC, what has promoted the higher zeta potential (-56.96 mV) for nanocrystals than for NFC (-26.86 mV). CNC showed cylindrical shape (85.48 nm length and 10.32 nm wide) while the NFC presented a more elongated shape (4.7 nm wide and length greater than 1μm). 3D profile of nanocelluloses shows the greatest morphological difference at the end of each production process, in which CNC are small rods with crystallinity (96.17 %) and NFC are elongated tubes with one of its dimensions at the nanoscale with higher content of amorphous areas and less crystallinity (79.30 %). The CNC presented a higher temperature of thermal degradation (375 °C) than the NFC (353 °C), and weight loss in the range of 300-400 °C for CNC than for NFC (200 -300 °C). FTIR spectra confirm the surface cellulosic polymers derivatives groups with emphasis on the peaks of 1205 cm-1 which shows the vibration for the linked sulfated groups (S=O) present in CNC due to acid hydrolysis, and the band of NFC in 1608 cm-1 indicating vibrations of carboxylic acids bonds, due to the presence of hemicellulose or oxidative treatments performed for the nanofibrils isolation. For both nanocelluloses types it occurred the degradation by a fungus of the genus Pleurotus sp., indicating no toxic potential. Conclusion: The nanocelluloses can be applied in many areas considering their properties and safety features classified as biodegradable biopolymers.