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Preparation of cellulose nanofibers from Miscanthus x. Giganteus by ammonium persulfate oxidation

Yang, Han, Zhang, Yefei, Kato, Ryo, Rowan, Stuart J.
Carbohydrate polymers 2019
Miscanthus, acid hydrolysis, ammonium persulfate, bleaching agents, carboxylic acids, cellulose, cellulose nanofibers, crystal structure, dispersibility, grasses, mechanical properties, nanocrystals, oxidation, polyvinyl acetate, storage modulus, thermal stability, thermogravimetry, ultrasonic treatment
Carboxylic acid functionalized cellulose nanofibers (MxG-CNFA-CO2H) were successfully isolated from a sustainable grass hybrid Miscanthus x. Giganteus by a new two-step chemical oxidation, that involves bleach treatment and ammonium persulfate oxidation, followed by ultrasonication. The resulting MxG-CNFA-CO2Hs have ca. 1200mmol/kg carboxylic acid surface groups, an aspect ratio of 230 (height of ca. 3.8±0.8nm and length of ca. 880±300nm) and 70% crystallinity. Interestingly, these MxG-CNFA-CO2Hs exhibit better thermal stability (as measured by thermal gravimetric analysis) and better dispersibility in DMF than corresponding cellulose nanocrystals (CNC) obtained from same biosource (MxG-CNC-CO2Hs) via acid hydrolysis. Poly(vinyl acetate):MxG-CNFA-CO2H composites show an increase in storage modulus (aboveTg) with increasing filler content. Importantly, the mechanical properties of the poly(vinyl acetate):nanocellulose composites showed that the MxG-CNFA-CO2Hs exhibit significantly better reinforcement than the MxG-CNC-CO2H at the same weight percent filler content.