RESUMEN
Two types of cellulose nanofibrils (CNFs) were isolated from cotton linter fibers and hardwood fibers through mechanical fibrillation methods. The dialdehyde cellulose nanofibrils (DACNFs) were prepared through the periodate oxidation method, and their morphological and structural properties were investigated. The characteristics of the DACNFs during the concentration process were also explored. The AFM analysis results showed that the mean diameters of wood fiber-based CNFs and cotton fiber-based CNFs were about 52.03 nm and 69.51 nm, respectively. However, the periodate oxidation treatment process obviously reduced the nanofibril size and destroyed the crystalline region of the nanofibrils. Due to the high crystallinity of cotton fibers, the cotton fiber-based DACNFs exhibited a lower aldehyde content and suspension stability compared to the wood fiber-based DACNFs. For the concentration process of the DACNF suspension, the bound water content of the concentrated cotton fiber-based DACNFs was lowered to 0.41 g/g, which indicated that the cotton fiber-based DACNFs could have good redispersibility. Both the wood fiber-based and cotton fiber-based DACNF films showed relatively good transmittance and mechanical strength. In addition, to the cotton fiber-based DACNF films had a very low swelling ratio, and the barrier water vapor and oxygen properties of the redispersed cotton fiber-based DACNF films decreased by very little. In sum, this study has demonstrated that cotton fibers could serve as an effective alternative to wood fibers for preparing CNFs, and that cotton fiber-based DACNFs have huge application prospects in the field of packaging film materials due to their stable properties during the concentration process.
RESUMEN
Employing renewable, environmentally friendly, low-cost lignocellulose to design flexible pressure sensitive hydrogel (PSH) as strain and pressure sensors in wearable electronics represents the global perspective to build sustainable and green society. Lignin-based carbon (LC), as the conductive filler, were uniform distributed in the hydrogel system composing by polyvinyl alcohol (PVA), carboxymethyl chitosan (CMC), and cellulose nanofibrils (CNF) to assemble PSH. The analysis revealed that the cross-linking of components through hydrogen bonds formed among hydroxyl group, amino group and carboxyl group exerts the hydrogel with stretching ability and fatigue resistance. The results indicated that the fracture tensile strength and compression stress of the PC/CNF/LC hydrogel were 133 kPa and 37.7 kPa, respectively. Because of the existence of LC, PSH hydrogel exhibits the sensitive deformation-dependent conductivity and can be applied as a flexible strain and pressure sensor monitoring body motions such as elbow flexion, finger bend and palm grip. Therefore, the assembled PSH hydrogel is a prominent candidate applying as the strain and pressure sensor devices.
