To prepare oxidized CF, a 9% CF dispersion (900 g) in water with 0.74% sodium hydroxide based on the dry weight of CF
was first hydrolyzed at 95 C for 1 h and cooled. After the hydrolysis, 0.5% copper(II) sulfate pentahydrate and 6% hydrogen
peroxide based on the dry weight of CF were added to the dispersion. The concentrations used are based on the literature
methods [16,17] to ensure a significant extent of oxidation on the hydroxyl functional groups. The mixture was then homogenized at 104 rpm for 45 min followed by stirring at 50 C for 1 h. After the oxidation, the dispersion was microfluidized
under the same condition mentioned above for 6 cycles. The oxidized CF with a higher level of oxidation was also prepared
with the same process except 28% of hydrogen peroxide was added in the process mentioned above.