Preparation of tannic acid-reinforced cellulose nanofiber composites for all-water-based high-performance wood adhesives.

Traditional adhesives easily release toxic gases during the preparation process or apply to wood composite products, which have adverse effects on the human body and the environment. Herein, an all-water-based high-performance wood adhesive is prepared using TEMPO-oxidized cellulose nanofiber (TOCNF), acrylamide (AM), and tannic acid (TA) through free radical polymerization. Different characteristics of the prepared composites, including morphology, injectability, and adhesion properties, have been investigated. Results showed that the TA/TOCNF/PAM composite has excellent injectability. The addition of TA can enhance the lap shear strength of the TA/TOCNF/PAM composites and with the increment of TA content, the lap shear strength gradually decreases. The formation of effective hydrogen bonds and Van der Waals interaction among the rich functional groups in the composite, lead to strong lap shear strength on different substrates. The composite with 5.0 g of AM, 5.0 g of the TOCNF suspension and 0.1 g TA possesses a high lap shear strength of 10.5 MPa on wood and 1.5 MPa on aluminium. Based on strong adhesion properties and excellent injectability, the TA/TOCNF/PAM composites have great potential in the furniture construction and building industries.

Cellulosic and hemicellulosic fractions of sugarcane bagasse: Potential, challenges and future perspective.

Sugarcane bagasse is a rich source of cellulose (32-45%), hemicellulose (20-32%) and lignin (17-32%), 1.0-9.0% ash and some extractives. Huge amount of the generation of sugarcane bagasse has been a great challenge to industries and environment at global level for many years. Though cellulosic and hemicellulosic fractions in bagasse makes it a potential raw substrate for the production of value-added products at large scale, the presence of lignin hampers its saccharification which further leads to low yields of the value-added products. Therefore, an appropriate pretreatment strategy is of utmost importance that effectively solubilizes the lignin that exposes cellulose and hemicellulose for enzymatic action. Pretreatment also reduces the biomass recalcitrance i.e., cellulose crystallinity, structural complexity of cell wall and lignification for its effective utilization in biorefinery. Sugarcane bagasse served as nutrient medium for the cultivation of diverse microorganisms for the production of industrially important metabolites including enzymes, reducing sugars, prebiotic, organic acids and biofuels. Sugarcane bagasse has been utilized in the generation of electricity, syngas and as biosorbant in the bioremediation of heavy metals. Furthermore, the ash generated from bagasse is an excellent source for the synthesis of high strength and light weight bricks and tiles. Present review describes the utility of sugarcane bagasse as sustainable and renewable lignocellulosic substrate for the production of industrially important multifarious value-added products.

The role of heteropolysaccharides in developing oxidized cellulose nanofibrils.

A fundamental study was undertaken to determine the general role of heteropolysaccharides during the production of TEMPO-oxidized cellulose nanofibrils (TOCNs). Four major fiber resources, viz., fully bleached kraft pulps of softwood and hardwood varieties (pine, eucalyptus) and non-woods (bamboo, bagasse) were used because of their substantial morphological differences and relative abundance. The effect of heteropolysaccharides during TEMPO-mediated oxidation and high-pressure homogenization for TOCNs production was investigated under constant conditions. Most galactoglucomannans were removed during oxidation, whereas the majority of xylans were retained. The galactoglucomannans, however, non-beneficially consumed NaClO, the terminal TEMPO oxidant, while xylans adversely affected carboxylate group formation by limiting chemical accessibility to cellulose. However, lower xylans content led to more transparent and processable suspensions, while during mechanical processing, heteropolysaccharides supported nanofibrillation. The average length of the final TOCNs from eucalyptus, bamboo, bagasse, and pine were 290, 350, 360 and 370nm, respectively, with average widths of ∼4nm.

Hydrolysis of various thai agricultural biomasses using the crude enzyme from Aspergillus aculeatus iizuka FR60 isolated from soil

In this study, forty-two fungi from soil were isolated and tested for their carboxymethyl cellulase (CMCase) and xylanase activities. From all isolates, the fungal isolate FR60, which was identified as Aspergillus aculeatus Iizuka, showed high activities in both CMCase and xylanase with 517 mU/mg protein and 550 mU/mg protein, respectively. The crude enzyme from A. aculeatus Iizuka FR60 could hydrolyze several agricultural residues such as corncob, and sweet sorghum leaf and stalk at comparable rates with respect to the tested commercial enzymes and with a maximum rate in rice hull hydrolysis (29 μg sugar g-1 dry weight substrate mg-1 enzyme hr-1). The highest amount of glucose was obtained from corncob by using the crude enzyme from A. aculeatus Iizuka FR60 (10.1 g/100 g dry substrate). From overall enzymatic treatment results, the lowest sugar yield was from rice hulls treatment (1.6 g/100 g dry weight) and the highest amount of reducing sugar was obtained from rice straw treatment (15.3 g/100 g dry weight). Among tested agricultural wastes, rice hull could not be effectively hydrolyzed by enzymes, whereas sugarcane leaf and stalk, and peanut shell could be effectively hydrolyzed (30-31% total sugar comparing with total sugar yield from acid treatment).

Optical monitoring for power law fluids during spin coating.

Optical monitoring is applied, in situ and in real time, to non-newtonian, power law fluids in the spin coating process. An analytical exact solution is presented for thickness evolution that well fits to most measurement data. As result, typical rheological parameters are obtained for several CMC (carboximetilcelullose) concentrations and rotation speeds. Optical monitoring thus precisely indicates applicability of the model to power law fluids under spin coating.

Surgicel: its fate following implantation.

Surgicel, a local haemostatic gauze, is claimed to consist of oxidised regenerated cellulose. It is a polyanion, the functional unit of which is termed polyanhydroglucuronic acid. The ability of tissues to absorb Surgicel and its inherent haemostatic properties have been extensively investigated. This study was undertaken a) to determine the time required for absorption of Surgicel from implantation sites in the chest wall muscles of rats, and b) to establish mechanisms for its removal. Data derived from sequential uronic acid assays, histochemistry using the stain alcian blue, and transmission electron microscopy of implanted Surgicel were interpreted to reveal that Surgicel consists of at least two active components. These are a soluble uronic acid component which is lost after 6 h, and a fibrous component which persists. The latter material resembles Surgicel in the electron microscope and is still evident at the implantation site at 48 h post-implantation. Moreover, Surgicel can be characterized in vitro into at least two components according to its solubility under dissociative salt conditions (4M guanidinium chloride). A residual fibrous material could then be hydrolysed with 0.3N sodium hydroxide. We postulate that the absorption of the former salt soluble uronate in vivo is by early degradation and/or systemic clearance, whilst removal of the fibrous material requires phagocytosis.

A chemical and engineering analysis of dust in textile mills.

Proximate chemical analysis was conducted on the carding, spinning and weave rooms of textile mills. The dust was found to be composed of inorganic, cellulosic and noncellulosic organics in carding and spinning. The percentage of noncellulosic organic (the component of cotton dust considered to be responsible for byssinosis in cotton textile workers) in ring spinning was found to be one-half the percentage composition of the card room dust. The cellulosic percentage of spinning room dust is elevated above that found in card rooms. In weave rooms the composition of dust is a function of the fabric being produced, environmental control systems, and machinery. In all weave rooms where dust levels were sufficiently above background, all components of the dust were accounted for by the proximate chemical analysis without the presence of a noncellulosic organic component. The card room, spinning room and weave room produce dusts that are very different in composition, to the extent that the proximate chemical analysis could identify the area of origin of dust samples from a textile mill.