The surface of ramie cellulose whiskers has been chemically modified by grafting organic acid chlorides presenting different lengths of the aliphatic chain by an esterification reaction. The occurrence of the chemical modification was evaluated by FTIR and X-ray photoelectron spectroscopies, elemental analysis and contact angle measurements. The crystallinity of the particles was not altered by the chain grafting, but it was shown that covalently grafted chains were able to crystallize at the cellulose surface when using C18.Both unmodified and functionalized nanoparticles were extruded with low density polyethylene to prepare nanocomposite materials. The homogeneity of the ensuing nanocomposites was found to increase with the length of the grafted chains. The thermomechanical properties of processed nanocomposites were studied by differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA) and tensile tests. A significant improvement in terms of elongation at break was observed when sufficiently long chains were grafted on the surface of the nanoparticles. It was ascribed to improved dispersion of the nanoparticles within the LDPE matrix.

In the present study, an innovative method to produce cellulose nanocrystals is proposed. The conventional production of nanocrystals uses concentrated solutions of strong acids to promote the hydrolysis of cellulose amorphous regions and hemicelluloses. However, in the conventional method, long duration washing steps and the nanocrystals low temperature resistance still limit their larger industrialization and some applications in processes or end-uses that require heat resistance, like extrusion. In this context, the use of subcritical water (120 °C and 20.3 MPa for 60 min) allows higher diffusion, activity, and ionization of water. With that, partial hydrolysis of cellulose can be attended (with 21.9 wt % NCC yield). The cellulose source, the hydrolyzed cellulose, and a commercial nanocellulose were submitted to different analytical techniques to evaluate their morphology and physicochemical characteristics. The obtained cellulose nanocrystals presented a high crystallinity index (79.0% by XRD), rod-like shape with a similar aspect ratio as those known for classic cellulose nanocrystals but also a higher thermal stability even when compared with the original cellulosic source (onset around 300 °C). The exclusive use of water as a reagent is a promising process not only for its green characteristics but also for its low corrosion, low and cleaner effluent, and low cost of reagents.

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The kinetics of sugar cane bagasse cellulose saccharification and the decomposition of glucose under extremely low acid (ELA) conditions, (0.07%), 0.14%, and 0.28% H 2 SO 4 , and at high temperatures were investigated using batch reactors. The first-order rate constants were obtained by weight loss, remaining glucose, and fitting glucose concentration profiles determined with HPLC using the Saeman model. The maximum glucose yields reached 67.6% (200°C, 0.07% H 2 SO 4 , 30 min), 69.8% (210°C, 0.14% H 2 SO 4 , 10 min), and 67.3% (210°C, 0.28% H 2 SO 4 , 6 min). ELA conditions produced remarkable glucose yields when applied to bagasse cellulose. The first-order rate constants were used to calculate activation energies and extrathermodynamic parameters to elucidate the reaction mechanism under ELA conditions. The effect of acid concentration on cellulose hydrolysis and glucose decomposition was also investigated. The observed activation energies and reaction orders with respect to hydronium ion for cellulose hydrolysis and glucose decomposition were 184.9 and 124.5 kJ/mol and 1.27 and 0.75, respectively.

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This paper describes the organosolv delignification of depithed bagasse using glycerol-water mixtures without a catalyst. The experiments were performed using two separate experimental designs. In the first experiment, two temperatures (150 and 190°C), two time periods (60 and 240 min) and two glycerol contents (20% and 80%, v/v) were used. In the second experiment, which was a central composite design, the glycerol content was maintained at 80%, and a range of temperatures (141.7-198.3°C) and time (23-277 min) was used. The best result, obtained with a glycerol content of 80%, a reaction time of 150 min and a temperature of 198.3°C, produced pulps with 54.4% pulp yield, 7.75% residual lignin, 81.4% delignification and 13.7% polyose content. The results showed that high contents of glycerol tend to produce pulps with higher delignification and higher polyoses content in relation to the pulps obtained from low glycerol content reactions. In addition, the proposed method shows potential as a pretreatment for cellulose saccharification.

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