Solvent-free acetylation of cellulose nanofibers for improving compatibility and dispersion

Cellulose nanocrystals reinforced environmentally-friendly waterborne polyurethane nanocomposites

“…In this case, WBPU matrix presents a considerably hydrophobic character which is reduced as CNC content is increased, even around 15º for WBPU-5. These results are attributable to the greater hydrophilicity of the nanocomposites provided by the hydrophilic character of CNC (Ashori, Babaee, Jonoobi, & Hamzeh, 2014;Hubbe, Gardner, & Shen, 2015;Ly et al, 2008). Similar deviation values of 2-3 º can be observed in the nanocomposites, which suggest that the films possess a homogeneous surface.…”

Nanocellulosic fillers for waterborne wood coatings: reinforcement effect on free-standing coating films

“…2 indicate significant changes in the chemistry of CNF after acetylation. Three characteristic bands are related to acetyl groups and therefore acetylated cellulose: the C=O stretching of carbonyl groups in the ester bonds around 1745-1740 cm -1 , the vibration peaks at 1240-1235 cm -1 due to stretching of C-O bonds and the methyl in-plane bending of C-CH 3 around 1375 cm -1 (Ashori et al 2014;Cetin et al 2009;Higgins et al 1961;Jonoobi et al 2010). All of them could be easily identified in the spectrum obtained for the modified CNF.…”

“…The acetylation of CNF was done according to protocols published in the literature (Ashori et al 2014;Ernest-Saunders et al 2014;Jonoobi et al 2010). As a first step, a solvent exchange from water to a mixture of acetone and methanol (2:1) was carried out.…”

How to decrease the hydrophilicity of wood flour to process efficient composite materials

“…Besides, the hydrophilicity of the wood filler results in another drawback: water is absorbed into the filler once incorporated into the polymer, leading to dimensional instability and thus to a degradation of the mechanical composite properties [9,10]. With the aim of changing the surface chemistry of the wood filler and of making it more compatible with the polymer, several chemical treatments may be used such as esterification [11][12][13][14][15] and reaction with alkaline solutions [9,[16][17][18]. Physical and thermal treatments were also performed [10,[19][20][21] such as curing [22] or corona discharge [23][24][25].…”