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Water-sorption studies and certain organic chemistry reactions require water removal from cellulosic samples. This is hindered by the strong interaction of cellulosic materials with water, and it remains uncertain if a completely anhydrous state can be reached under common drying conditions. Here, different drying conditions were applied to wood and cellulose, and the residual moisture contents were quantified either gravimetrically or by coulometric Karl-Fischer titration. Vacuum-drying at 103 °C and ≤ 1 mbar for at least 360 min decreased the moisture content to ≤ 0.04%. However, in automated sorption balances, drying at atmospheric pressure under dry air or nitrogen flow left some samples with more than 1% moisture content. The residual moisture content obtained under dry gas flow was temperature dependent. Increasing the temperature up to 55 °C decreased the residual moisture content and cooling resulted in a moisture re-uptake, presumably due to small quantities of water vapor in the surrounding atmosphere. These effects must be considered in fundamental studies on water interactions of cellulosic materials.

Cotton fabrics were subjected to modification with fluorine-free polysiloxanes. In the first stage a series of polysiloxanes substituted with alkoxysilyl groups and/or alkyl chains were synthesized. Two methods of functionalization of vinyl group-containing polysiloxanes were used, i.e. hydrosilylation and hydrothiolation. Cotton fabrics were modified via dip-coating technique in solutions of the prepared compounds or by thiol–ene click reaction directly on the surface of cotton. In the first stage of the latter method cotton fabrics were modified by sol–gel technique with 3-mercaptopropyltrimethoxysilane in order to obtain mercapto-functionalized samples. After grafting SH groups on the surface, the fabrics were easily functionalized using the photoclick thiol–ene reaction with vinyl groups containing polysiloxane or vinyl- and alkyl-groups containing polysiloxane. The hydrophobicity was determined by measuring the water contact angle. Changes in the surface morphology were examined by FTIR spectroscopy and scanning electron microscopy (SEM). The coatings of the modified fabrics were subjected to elemental analysis using SEM–EDS techniques. All modified cotton fabrics showed highly hydrophobic properties. All obtained hydrophobic fabrics were fully resistant to the washing process, which proves the durability of the developed modifications.

With the increasing importance of electronic devices in modern industry, considerable efforts have been devoted to solving the problem that the electronic devices fail to work normally in a cold environment. Herein, we designed and fabricated a graphene wrapped wood-based phase change composite with electro-thermal conversion and energy storage capabilities by delignification of natural wood, coverage and reduction of graphene oxide (GO), impregnation of 1-tetradecanol (TD) and package of epoxy resin. The phase change composite exhibited large latent heat of fusion (218.5 J/g), excellent shape stability with high TD packing content of 88.4% and favorable reliability even after 50 heating–cooling cycles. More importantly, the Joule heat conversed by the rGO layer under voltage was able to quickly transfer to the surrounded TD, leading to the increase of the overall temperature of the composite and the efficient storage of energy. The findings conceivably stand out a sustainable strategy to fabricate an electrically driven wood-based phase change composite for preheating and heat preservation of electronics.

Pulp fibers are among the most abundant and cost effective cellulose source for the fabrication of polymer-cellulose composites. A straightforward method is to impregnate pulp fibers into thermoplastic films by hot press forming. As such, tissue materials made from hard or soft wood lignin-free Kraft fibers are attractive. In this work, we prepared cellulose fiber-polylactic acid (PLA) composite films by impregnating PLA films into a 40 g/m2 tissue paper texture. A PLA film was sandwiched between single and multiple layers of cellulose tissues by hot pressing, forming composite films. Up to 40 wt% cellulose could be incorporated into PLA in this way. The effect of cellulose fiber content on the composite thermomechanical properties has been studied and reported. A natural terpene, limonene, was infused into the cellulose fibers by immersion coating to produce antioxidant composites. Limonene-modified composites demonstrated long-term antioxidant release and activity for three days, verified by 2, 2-Diphenyl-1-picrylhydrazyl (DPPH), cupric ion reducing antioxidant capacity (CUPRAC) and free iron ions (Fe2+)/ferrozine chelating assays separately. The short-term (2 h) antioxidant activity of the biocomposites reached 50–70% levels depending on the cellulose fiber concentration for the DPPH and CUPRAC assays but remained lower at 20–55% levels in the metal chelating assay. Due to sustained release of limonene from the composites, at the end of the 5-day period, the iron chelating antioxidant activity of the composites improved reaching 75%, whereas for DPPH and CUPRAC assay, 90% activity was recorded. These biocomposite films can be used in active protective packaging of both food (fruit) and cosmetic products.

In this study we employed Size Exclusion Chromatography (SEC) and X-ray diffraction to monitor the molecular weight and crystallinity of bacterial cellulose I and II (BC-I, BC-II) and microcrystalline cellulose (MCC) digested with three “pure” Thermobifida fusca cellulases (Cel6A, Cel6B, and Cel9A ). For each enzyme, cellulose crystallinity was found to increase modestly with treatment time. The digestion rate of BC-II was higher than that of BC-I for Cel6A and Cel9A, both endocellulases. SEC results show that the endocellulases create a very rapid decrease in cellulose molecular weight while a slower molecular weight loss was observed with Cel6B, an exocellulase. This work suggests that conversion of native cellulose I to cellulose II by mercerization may beneficially impact the rate of sugar release by cellulases from biomass. In general, lower conversion rates are observed for MCC compared to BC, possibly due to a higher initial crystallinity for MCC. Surface area effects may also be important.

Microfluidization, which is a high-pressure homogenization technique, was used to develop highly dispersed cellulose nanocrystal (CNC) reinforced chitosan based nanocomposite films. A three factor central composite design with five levels was designed to systematically optimize the microfluidization process. The three factors were the CNC content, the microfluidization pressure and the number of microfluidization cycles. Response surface methodology was used to obtain relationship between the mechanical properties of the nanocomposite films and the factors. Polynomial equations were generated based on the regression analysis of the factors and the predicted properties of the nanocomposite films were in good agreement with the experimental results. Microfluidization effectively reduced the CNC–chitosan aggregates and improved the mechanical properties of the nanocomposite films. Microscopic analysis of the microfluidized nanocomposite films revealed a 10–15 times reduction in the size of the aggregates compared to the non-microfluidized CNC/chitosan films and an increase in the root mean square surface roughness (Rq).

With the increased use of nanocelluloses as additives in many industrial applications, better characterization methods are needed to ensure their effectiveness. Transmission electron microscopy (TEM) is an appropriate image acquisition system to enable their morphological characterization. The use of TEM has typically been focused on determining the diameter and length of individual cellulose nanocrystals (CNCs) or nanofibers (CNFs), so different dispersion practices, such as sonication or the use of dispersants, are commonly applied to separate the particles. However, this study aims to improve the characterization of the bulk morphology of CNCs and CNFs by TEM, taking steps towards the determination of the aggregation/dispersion degree as well as the fibrillation degree of CNFs. TEM has been investigated with two types of grids (holey and Formvar/carbon), three different fixing methods (Poly-l-Lysine, glow discharge and UV radiation) and the use of negative staining. Fractal dimension and lacunarity were used to quantify the reproducibility of the improved method. With the use of Poly-l-Lysine, the attachment of CNCs and CNFs particles on the TEM grids was ensured, due to the electrostatic interactions between negatively charged nanocelluloses and positively charged and hydrophilic Poly-l-Lysine surfaces. The low value of lacunarity, close to 0.3, shows a very high reproducibility of the methodology proposed. With this new approach, the state that the nanocelluloses have in suspension can be directly characterized by TEM.

In the domain of energetic materials (EMs), the high-energy and high-safety EMs have infinite promising in modern defense weapons. Herein, this study prepared a novel nitrated bacterial cellulose/cyclotrimethylenetrinitramine (NBC/RDX) nanocomposite energetic material via a straightforward, mild and safe sol–gel method and freeze-drying technology. A unique and stable three-dimension (3D) porous network nanostructure of the composites was characterized by a series of analytical and test methods. It was found that the RDX crystals were distributed and imbedded uniformly in the NBC binder matrix, leading to the formation of nanometer-scale composites. The thermal properties presented remarkable decreased peak temperature (RDX: 236.60 °C → NBC/RDX-55%: 217.20 °C) and increased Ea (from 108.00 → 155.25 kJ/mol) during the decomposition process. Furthermore, thermal decomposition reaction kinetics and thermodynamics have also been calculated by two traditional methods: the Kissinger and Ozawa methods, indicating a promoted decomposition behavior compared with raw RDX and NBC. Moreover, TG-DSC-IR-GC–MS technology has been further conducted to probe the mechanism of decomposition, manifesting the formation of crosslinking structure of NBC gel matrix would decompose firstly and followed by the decomposition of RDX. Lastly, the sensitivity test demonstrated that the formation of 3D porous crosslinking network nanostructure of NBC gel matrix exerted remarkably desensitization effect when encountering external stimuli, and three categories of reduction sensitivity mechanism has been proposed. Hence, this synthesis strategy has profound basic theory research significance and may provide promising application of NBC/RDX nEMs used in high-energy and high-strength propellants.