High Klason lignin content (23 wt%) cellulose nanofibrils (LCNF) were successfully isolated from eucalyptus pulp through catalyzed chemical oxidation, followed by high-pressure homogenization. LCNFs had a diameter of ca. 13 nm according to AFM evaluation. Dense films were obtained through vacuum filtration (nanopaper) and subjected to different drying methods. When drying under heat and mild vacuum (93°C, 95 kPa) a higher water contact angle, lower roughness and oxygen transmission rate were observed, compared to those drying at room temperature under compression conditions. DSC experiments showed difference in signals associated to T g of LCNF compared to CNF produced from spruce bleached pulp through enzymatic pre-treatment. The LCNF-based nanopaper showed mechanical properties slightly lower than for those made from cellulose nanofibrils, yet with increased hydrophobicity. In summary, the high-lignin content cellulose nanofibrils proved to be a suitable material for the production of low oxygen permeability nanopaper, with chemical composition close to native wood.

No abstract

Barrier, mechanical and thermal properties of porous paper substrates dip-coated with nanocellulose (NC) were studied. Sorbitol plasticizer was used to improve the toughness, and citric acid crosslinker to improve the moisture stability of the coatings. In general, the addition of sorbitol increased the barrier properties, maximum strength and toughness as well as the thermal stability of the samples when compared to the non-modified NC coatings. The barrier properties significantly improved, especially for plasticized NC coating's, where the oxygen permeability value was as low as 0.7 mL lm day -1 m -2 kPa -1 at 49% RH and the water vapor permeability was reduced by 60%. Furthermore, we found that the cross-linked plasticized NC coating had a smoother surface (50% lower roughness) compared to non-modified ones. This study shows that the environmentally friendly additives sorbitol and citric acid had positive effects on NC coating properties, increasing its potential use in paperbased packaging applications.

No abstract

No abstract

The fact of cellulose been the structural component of the primary cell wall of green plants and some algae, makes it one of the most abundant and naturally occurring polymers on earth. However, cellulose nanowhiskers (CNW) are not commercially available till date. CNWs are rod-like shaped nano-sized crystals that can be obtained from different natural resources.Recently there is an interest to use bioresidues to isolate CNWs to provide value-add to the natural resources and help the economy of the companies. Our earlier studies have shown that it's possible to extract CNW from industrial bioresidues [1].In order to determine if these industrial bioresidues are an option for the production of CNW, the characteristics of nanowhiskers extracted from bioethanol residue (ER), by homogenization, and sludge (SL) from cellulose production, extracted by sulfuric acid hydrolysis, were compared with CNW extracted from commercial microcrystalline cellulose (MCC) by sulfuric acid hydrolysis. The schematic representation of the isolation route adopted for the studied materials are given in Figure 1.The flow birefringence of aqueous suspensions of the CNWs were analyzed through a set of cross polarized filters and a lamp, to understand if the nanocrystals are isolated. The morphology of the whiskers was analyzed with an atomic force microscope (AFM) in tapping mode, on a drop of CNW solution dried over freshly cleaved mica sheet.Films from each suspension were prepared by solution casting to obtain films of ≈ 40 µm of thickness. On these films, the UV/Vis spectroscopy, X-ray diffraction and thermal analysis (TGA) were studied.The results showed that these bioresidues are possible sources for the production of CNW. AcknowledgmentsThe authors would like to thanks to Bio4Energy for the financial support. Reference 1. Oksman K. Cellulose nanowhiskers separated from a bio-residue from wood bioethanol production. Biomass Bioenergy 2011;35(1):146-52.

No abstract