2.3. Hydrolysis of BC to obtain CNCs
Acid hydrolysis of BC (previously dispersed in water) was carried
out by stirring BC continuously in 60% (w/w) H2SO4 at 60 C for 1 h
[31] to produce CNCs with average dimensions 25 nm 280 nm.
Specifically, the amount of H2SO4 solution used for the hydrolysis
was based on the dry weight of cellulose (800 ml solution per 1 g
dry weight cellulose). After hydrolysis, the suspension was centrifuged
and diluted several times, until pH neutral. The CNCs were
solvent exchanged from deionised water (dH2O) into dioxane
through acetone (3 times per solvent exchange, with centrifugation
and homogenization steps in between) and a sample taken in order
to ascertain their wet:dry ratio for the production of PLA/CNC composite
feedstock, described below.