Production of nanocrystals and nanofibrils from unbleached and bleached soda pulp with ECFlight bleaching sequence and comparison of their morphological and thermal properties

In this study, pulp nanocrystals (PNCs) and pulp nanofibrils (PNFs) were extracted from bleached soda pulp with D0EpD1 sequence, and their characteristics were compared with lignocellulosic nanocrystals (LCNCs) and lignocellulosic nanofibrils (LCNFs) obtained from unbleached soda pulp. LCNCs were extracted with an acid hydrolysis method using sulfuric acid (64 wt%) at 45◦C for 45 minutes with a liquor to fiber ratio of 17.5: 1 and LCNFs were produced via microfluidizer by passing through three chambers with diameters of 50, 100, and 200 μm for 2, 4, and 6 hours, respectively. SEM and AFM images confirmed the needle-like and spherical-like structure of lignocellulosic nanocrystals and the stringy structure of lignocellulosic nanofibrils. XRD results showed that D0EpD1 bleaching increased the crystallinity of nanolignocelluloses. The results obtained from TGA thermal calorimetry analysis show that D0EpD1 bleaching increases the thermal stability of the produced PNCs and decreases the thermal stability of the produced PNFs. FTIR results confirmed that the amount of hemicelluloses and lignin was reduced from the fiber surface after D0EpD1 bleaching sequence