Comparative study of cellulose and lignocellulose nanopapers prepared from hard wood pulps: Morphological, structural and barrier properties

Screw extrusion pretreatment for high-yield lignocellulose nanofibrils (LCNF) production from wood biomass and non-wood biomass

To develop a facile and low-cost nanofibrils process with excellent feedstock adaptability, high-yield lignocellulose nanofibrils (LCNF) are produced directly from wood and non-wood biomass using glycerol solvent via screw extrusion pretreatment. Different LCNFs are obtained from four classical raw materials (polar, pine, bamboo, and wheat straw) in this research, followed by comparing their morphological, thermochemical, and mechanical properties. More than 70 wt% of LCNF could be obtained from low-cost substrates except for LCNF from wheat straw with 62.3 wt% yield. Besides, the morphology property of wood LCNF exhibit more uniform distribution over that of non-wood LCNF due to narrower size distribution. Strikingly, despite of the slightly lower LCNF crystallinity various from 52.4% to 62.6% obtained from four substrates, all the LCNFs separated from wood and non-wood biomass exhibit high thermal stability (T_max over 330 °C), which is higher than conventional nanocellulose, indicating that the crystal area could be well maintained during the pretreated process. Moreover, all the LCNF films show excellent tensile strength which is close to nanocellulose materials. Besides, the Young's modulus of wood-based LCNF films is higher than that of non-wood based LCNF films. Overall, LCNF with excellent performance could be achieved from low-cost biomass by our facile process, which provides a feasible route for industrial production of bio-based nanofilms.

Recent Advances in Cellulose Nanofibers Preparation through Energy-Efficient Approaches: A Review

Cellulose nanofibers (CNFs) and their applications have recently gained significant attention due to the attractive and unique combination of their properties including excellent mechanical properties, surface chemistry, biocompatibility, and most importantly, their abundance from sustainable and renewable resources. Although there are some commercial production plants, mostly in developed countries, the optimum CNF production is still restricted due to the expensive initial investment, high mechanical energy demand, and high relevant production cost. This paper discusses the development of the current trend and most applied methods to introduce energy-efficient approaches for the preparation of CNFs. The production of cost-effective CNFs represents a critical step for introducing bio-based materials to industrial markets and provides a platform for the development of novel high value applications. The key factor remains within the process and feedstock optimization of the production conditions to achieve high yields and quality with consistent production aimed at cost effective CNFs from different feedstock.

Surface and Interface Engineering for Nanocellulosic Advanced Materials

How do trees support their upright massive bodies? The support comes from the incredibly strong and stiff, and highly crystalline nanoscale fibrils of extended cellulose chains, called cellulose nanofibers. Cellulose nanofibers and their crystalline parts-cellulose nanocrystals, collectively nanocelluloses, are therefore the recent hot materials to incorporate in man-made sustainable, environmentally sound, and mechanically strong materials. Nanocelluloses are generally obtained through a top-down process, during or after which the original surface chemistry and interface interactions can be dramatically changed. Therefore, surface and interface engineering are extremely important when nanocellulosic materials with a bottom-up process are fabricated. Herein, the main focus is on promising chemical modification and nonmodification approaches, aiming to prospect this hot topic from novel aspects, including nanocellulose-, chemistry-, and process-oriented surface and interface engineering for advanced nanocellulosic materials. The reinforcement of nanocelluloses in some functional materials, such as structural materials, films, filaments, aerogels, and foams, is discussed, relating to tailored surface and/or interface engineering. Although some of the nanocellulosic products have already reached the industrial arena, it is hoped that more and more nanocellulose-based products will become available in everyday life in the next few years.

Environmentally friendly superabsorbent fibers based on electrospun cellulose nanofibers extracted from wheat straw

Superabsorbent polymers currently used in health and agricultural sectors are based on petroleum-based materials which led to serious concerns in the society. Here, superabsorbent fibers (SAFs) based on electrospun cellulose nanofibers (ECNFs) were prepared. Firstly, cellulose was removed from wheat straw, pre-treated with the TEMPO-mediated oxidation and subsequently dissolved into Trifluoroacetic acid for production of ECNFs through the electrospinning approach. The maximum swelling ratios of 225 g/g and 208 g/g in distilled water and 0.9 wt% NaCl solution were measured for ESAFs composed of oxidized ECNFs containing 15 % poly (sodium acrylate), respectively. The ESAFs were characterized using Fourier transform infrared spectroscopy and field emission scanning electron microscopy analysis. The FESEM showed that ESAFs formed high strength three-dimensional architecture networks. Also, the results showed that the ionic sensitivity of this ECNFs were low. The prepared ESAFs are attractive renewable alternatives for different applications, contributing to a reduction of plastic microspheres.