Individual Cellulose Research Articles

Cellulose nanomaterial metrology: microscopy measurements.

Cellulose nanomaterials are increasingly used for a wide variety of applications. Adequate characterization of these materials is required for quality control during production, to distinguish between materials synthesized by different methods, by different suppliers or from difference cellulose biomass sources, to facilitate development of applications and for regulatory purposes. Here we review recent microscopy measurements for the three main types of cellulose nanomaterials: cellulose nanocrystals, individual cellulose nanofibrils and cellulose nanofibrils. Atomic force microscopy and both scanning and transmission electron microscopy are covered with a focus on recent studies that have metrological rigor, rather than qualitative investigations. In some cases results are compared to those obtained by other methods that are more likely to see widespread use for routine quality control measurements. Detailed studies that use microscopy to provide insight on fundamental material properties (e.g., chiral properties) are also included. Particle size and morphology are important properties but are challenging to measure for cellulose nanomaterials due to the rod or fibril shaped particles, their propensity to agglomerate and aggregate, their low contrast for electron microscopy and, for cellulose nanofibrils, the complex branched and interconnected structures. Overall, the results show that there are now a number of studies in which attention to metrological detail has resulted in measurements that allow one to compare and distinguish between different materials, although there are still examples for which it is not possible to draw conclusions on size differences. The use of detailed microscopy protocols that yield accurate and reliable results will be beneficial in material production and addressing regulatory requirements and will allow the validation of other methods that are more amenable to routine measurements.

One-pot fabrication of hydrophobic, superelastic, harakeke-derived nanocellulose aerogels with excellent shape recovery for oil adsorption and water-in-oil emulsion separation

Cellulose-based aerogels have attracted significant attention for oil/water separation due to their high porosity, large specific surface area and high adsorption capacity. However, their intrinsic hydrophilicity, and inadequate mechanical properties have often limited their practical applications. Traditional freeze-dried cellulose aerogels exhibit unsatisfactory elasticity and require a separate surface modification process to adjust the surface wettability. In this study, we present a novel one-pot fabrication strategy which simultaneously achieves the crosslinking of individual cellulose nanofibers and the hydrophobic modification of the surface wettability. Following directional freeze-drying, hydrophobic, superelastic, and anisotropic cellulose-based aerogel was prepared from the 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibers, isolated from harakeke (New Zealand native flax). The resulting aerogel exhibits a high water contact angle of 142°, good compressive recovery performance (85 % recovery of the original height after 100 compression cycles at 70 % strain), and outstanding adsorption capacity for various types of oil and organic solvents (80–105 g/g). Furthermore, the aerogel could also be used as a filter to separate surfactant stabilized water-in-oil emulsions with a high flux (782 L m−2 h−1) and a high separation efficiency (98.7–99.2 %). The novel aerogel prepared in this study is expected to have great potential for practical applications in oily wastewater remediation.

Hydrogen production through polyoxometalate catalysed electrolysis from biomass components and food waste

Electrolysis from biomass is a promising process for hydrogen generation from biomass and biowaste that is still unexplored. The paper used lignocellulosic biomass components and food waste (banana and cucumber peels) as feedstocks to explore hydrogen generation through an H-type proton exchange membrane electrolytic cell. Polyoxometalates (PMo12) were employed as a catalyst and charge carrier during the pre-treatment stage in the biomass degradation process. Electrochemical characterisations were conducted in a potential range of 0–1.20 V to analyse the electrochemical reaction behaviour at the anode. To assess the impact of temperature on the hydrogen yield rates, the electrolysis was conducted at both room temperature (19 °C) and a higher temperature (80 °C). Results show that the maximum hydrogen produced in the first hour was 7.8 mL per gram of biomass. With an electrical potential of 1.20 V and a temperature of 80 °C, the hydrogen yield rate of glucose was three times higher than that of the individual biomass components, i.e., cellulose, lignin, hemicellulose, and starch. The volume of hydrogen yielded from banana peel and cucumber was 49.2 mL and 39.6 mL, respectively. The overall conversion efficiency was calculated as the weight percentage ratio of the hydrogen contained in cucumber and banana peels and the hydrogen collected was 10 % and 17 %, respectively, suggesting the need to identify solutions to extract the hydrogen content from biomass material further.

Experimental analysis of the effects of feedstock composition on the plastic and biomass Co-gasification process

Co-gasification is a feasible approach to manage fast-growing plastic and biomass waste issues. The current work examines air gasification of plastic waste blending with biomass. The influence of plastic-type and biomass characteristics on product distribution under the same operating condition was studied. Ethylene-vinyl acetate, high-density polyethylene, and polypropylene were the investigated plastics while the biomass materials considered were pine sawdust (PS), used ground coffee (UGC), and wheat straw (WS) are compared. Additionally, co-gasification and thermogravimetric analyses (TGA) of plastic and individual biomass components, namely, cellulose, hemicellulose, and lignin, were conducted to identify the nature of the synergy arising from plastic and biomass integration. Similarities in the chemical structure and composition of the investigated plastics resulted in the type of plastic marginally influencing product distribution. The gas composition included 4.6 vol% CH4, 37.5 % CO2, 5.3 % CnHm, 42 % CO, and 10.8 % H2, with yields of 5.9 wt% char, 39.5 wt% gas, and 54.8 wt% tar. Conversely, the type of biomass had a substantial effect on both gas composition and product yields. WS and UGC, characterized by higher hemicellulose and lignin content, generated more hydrogen with 14.4 and 13.3 vol%, respectively, and exhibited lower tar content (45.7 and 47.8 wt%) compared to PS, which has a higher cellulose content and yielded 54.8 wt% tar. During EVA/cellulose co-gasification, the predominant gases produced are CO and CO2, with H2 concentration of 7.2 vol%. In contrast, co-gasification of EVA/xylan and EVA/lignin yields 13.5 and 19.9 vol% hydrogen, respectively. Interactions and synergism between the plastic and biomass were found to be more intensified when the biomass contained greater proportions of cellulose and lignin. Co-gasification and TGA analyses indicated that plastic/cellulose and plastic/lignin interactions in the gas and solid phases (volatile-volatile and volatile-char interactions) and plastic/xylan interactions in the gas phase (volatile-volatile interactions) were significant. Modeling the predictability of the output data revealed that if interactions between the plastic and biomass components are accounted for, the co-gasification results are predictable with a credible accuracy for all biomass types. The predictability model offers a practical approach for selecting an appropriate co-gasification feedstock combination to give a targeted process performance.

Dynamic Structural Change of Plant Epidermal Cell Walls under Strain.

The molecular foundations of epidermal cell wall mechanics are critical for understanding structure-function relationships of primary cell walls in plants and facilitating the design of bioinspired materials. To uncover the molecular mechanisms regulating the high extensibility and strength of the cell wall, the onion epidermal wall is stretched uniaxially to various strains and cell wall structures from mesoscale to atomic scale are characterized. Upon longitudinal stretching to high strain, epidermal walls contract in the transverse direction, resulting in a reduced area. Atomic force microscopy shows that cellulose microfibrils exhibit orientation-dependent rearrangements at high strains: longitudinal microfibrils are straightened out and become highly ordered, while transverse microfibrils curve and kink. Small-angle X-ray scattering detects a 7.4nm spacing aligned along the stretch direction at high strain, which is attributed to distances between individual cellulose microfibrils. Furthermore, wide-angle X-ray scattering reveals a widening of (004) lattice spacing and contraction of (200) lattice spacing in longitudinally aligned cellulose microfibrils at high strain, which implies longitudinal stretching of the cellulose crystal. These findings provide molecular insights into the ability of the wall to bear additional load after yielding: the aggregation of longitudinal microfibrils impedes sliding and enables further stretching of the cellulose to bear increased loads.

Elucidating fungal decomposition of organic matter at sub-micrometer spatial scales using optical photothermal infrared (O-PTIR) microspectroscopy.

In microbiological studies, a common goal is to link environmental factors to microbial activities. Both environmental factors and microbial activities are typically derived from bulk samples. It is becoming increasingly clear that such bulk environmental parameters poorly represent the microscale environments microorganisms experience. Using infrared (IR) microspectroscopy, the spatial distribution of chemical compound classes can be visualized, making it a useful tool for studying the interactions between microbial cells and their microenvironments. The spatial resolution of conventional IR microspectroscopy has been limited by the diffraction limit of IR light. The recent development of optical photothermal infrared (O-PTIR) microspectroscopy has pushed the spatial resolution of IR microspectroscopy beyond this diffraction limit, allowing the distribution of chemical compound classes to be visualized at sub-micrometer spatial scales. To examine the potential and limitations of O-PTIR microspectroscopy to probe the interactions between fungal cells and their immediate environments, we imaged the decomposition of cellulose films by cells of the ectomycorrhizal fungus Paxillus involutus and compared O-PTIR results using conventional IR microspectroscopy. Whereas the data collected with conventional IR microspectroscopy indicated that P. involutus has only a very limited ability to decompose cellulose films, O-PTIR data suggested that the ability of P. involutus to decompose cellulose was substantial. Moreover, the O-PTIR method enabled the identification of a zone located outside the fungal hyphae where the cellulose was decomposed by oxidation. We conclude that O-PTIR can provide valuable new insights into the abilities and mechanisms by which microorganisms interact with their surrounding environments.IMPORTANCEInfrared (IR) microspectroscopy allows the spatial distribution of chemical compound classes to be visualized. The use of conventional IR microspectroscopy in microbiological studies has been restricted by limited spatial resolution. Recent developments in laser technology have enabled a new class of IR microspectroscopy instruments to be developed, pushing the spatial resolution beyond the diffraction limit of IR light to approximately 500 nm. This improved spatial resolution now allows microscopic observations of changes in chemical compounds to be made, making IR microspectroscopy a useful tool to investigate microscale changes in chemistry that are caused by microbial activity. We show these new possibilities using optical photothermal infrared microspectroscopy to visualize the changes in cellulose substrates caused by oxidation by the ectomycorrhizal fungus Paxillus involutus at the interface between individual fungal hyphae and cellulose substrates.

Unlocking the potential of pequi (Caryocar brasiliense) residues for bioenergy and renewable chemicals: Multicomponent kinetic modeling, thermodynamic parameter estimation, and characterization of volatile products through TGA and Py-GC/MS experiments

The first study in the literature on the pyrolysis of pequi (Caryocar brasiliense) residues, focusing on the kinetic triplet, thermodynamic parameters, and characterization of volatile products utilizing TGA and Py−GC/MS techniques, is presented in this paper. Slow pyrolysis experiments were conducted on a thermogravimetric scale in a controlled atmosphere of pure nitrogen, with five distinct heating rates (5, 10, 20, 30 and 40 ºC min−1). The pyrolysis progress profiles were fitted using the Asym2Sig function to deconvolute the devolatilization rates of individual biomass pseudo-components, including extractives, hemicellulose, cellulose, and lignin. The average activation energies for pequi peel pyrolysis, as determined by the isoconversional methods of Friedman, Flynn−Wall−Ozawa, Kissinger−Akahira−Sunose and Starink, were higher (114.30 −319.13 kJ mol−1) than those estimated for pequi seeds (88.05 −168.39 kJ mol−1). The pre-exponential factors, obtained through the kinetic compensation effect method, exhibited a range of values between 3.6 × 1011 and 2.4 × 1030 min−1 for pequi peel and between 1.2 × 107 and 9.4 × 108 min−1 for pequi seeds. Utilizing the master-plots method revealed the involvement of F-type, A-type, and D-type reaction models in the pyrolysis of pequi residues. A slight difference between the Ea and ΔH values, less than 5 kJ mol−1, indicates the facile formation of reaction products during pyrolysis. The main organic volatile products obtained from the fast pyrolysis of pequi peel, as revealed by Py−GC/MS analysis, include furans, ketones, aldehydes, and ethers, constituting up to 52% of the total yield of the condensable fraction at 550 °C. Aliphatic hydrocarbons are the major organic volatile products derived from the fast pyrolysis of pequi seeds, accounting for approximately 74% of the total condensable fraction yield at 650 °C. This study provides new insights into the valorization of residues resulting from pequi fruit processing. As a result, a novel pathway for bioenergy and biobased chemical production via pyrolysis is established, aligning with the circular economy principle and capable of promoting energy matrix diversification.

Synergistic interaction for catalytic co-pyrolysis of municipal paper and polyethylene terephthalate wastes coupling with deep learning methodology

Municipal papers and polyethylene terephthalate (PET) wastes are primary constituents of municipal solid waste (MSW) which necessitates effective disposal. Co-pyrolysis is an efficient transformation technology for the production of valuable gas and liquid fuels. Therefore, co-pyrolysis characteristics, kinetics, gas and liquid products of cellulose and PET mixtures were investigated in a two-stage reactor by multiple characterizations coupling with deep learning approach. The results indicated that there exhibited positive interaction for cellulose and PET co-pyrolysis in terms of mass difference (δm) and mass loss rate difference (δr) between experimental and calculated values. The thermal decomposition process and synergistic effects (δm and δr) were accurately predicted by deep learning approaches (R2 =0.9823–0.9993) using temperature, catalyst, mixing ratio and heating rate variables. Feature importance revealed that the temperature, catalyst, heating rate and mixing ratio were in the descending order to affect the remaining mass from TG curves. And the temperature played a predominant role in synergistic effects. The Flynn-Wall-Ozawa (FWO) method was more suitable for fitting the pyrolysis process to obtain activation energy (Ea) with higher R2 (0.94714–0.99640) compared with Kissinger-Akahira-Sunose (KAS) method. When the mixing ratio of cellulose and PET was 1:1, the Ea was significantly reduced to 80.73 KJ/mol, and further reduced to 73.04 KJ/mol by introducing the catalyst, as compared to Ea of individual cellulose (178.95 KJ/mol) and PET (198.34 KJ/mol). Co-pyrolysis of cellulose and PET led to a reduction of carbohydrates, furans, alcohols, ketones, and phenols, while the content of acids was remarkably increased which was consistent with the observation in FTIR that the absorption peak of C＝O became sharp and strong. The introduction of ZSM-11 resulted in an increase in aromatics and a decrease in acids content owing to aromatization and deoxygenation. This work is expected to offer beneficial guidance for the efficient disposal of MSW and the application of deep learning methods.

Biomass-based single- and double-network hydrogels derived from cellulose microfiber and chitosan for potential application as plant growing substrate

A series of hydrogels were synthesized from renewable and low-cost micro-sized cellulose fiber. The single-network hydrogel was composed of cellulose fiber and a small amount of another polysaccharide, chitosan, which ‘glued’ individual cellulose fiber pieces together through Schiff-base bonding. The double-network hydrogel was constructed by adding a secondary network, the covalently crosslinked polyacrylamide, into the single-network hydrogel, which was synthesized by conducting Schiff-base reaction and free radical polymerization at the same time in a facile one-pot process. In both single- and double-network hydrogels, cellulose fiber constituted the dominant component. Both types of hydrogels exhibited good swelling properties. The double-network hydrogel showed much improved stability against soaking in water and higher salt tolerance. Germination experiment with choy sum seeds sowed on hydrogel surface showed that the seeds were able to germinate and further develop roots, shoots, and true leaves, demonstrating the potential of the biomass-derived hydrogels for soilless plant growing applications.

Supramolecular Materials Chemistry in the MacLachlan Group

AbstractThis invited Team Profile was created by the MacLachlan group at the University of British Columbia. They recently published an article on the uniform growth of a metal–organic framework, ZIF‐8, on the surface of individual cellulose nanocrystals (CNCs). After the ZIF‐8/CNC fibers had been coated with a microporous organic polymer, the ZIF‐8 was removed to leave a microporous polymer with CNCs encapsulated in a ship‐in‐a‐bottle architecture. This material proved to be effective for CO2 fixation. “Uniform Growth of Nanocrystalline ZIF‐8 on Cellulose Nanocrystals: Useful Template for Microporous Organic Polymers”, K. Cho, L. J. Andrew, M. J. MacLachlan, Angew. Chem. Int. Ed. 2023, e202300960.

Supramolecular Materials Chemistry in the MacLachlan Group.

This invited Team Profile was created by the MacLachlan group at the University of British Columbia. They recently published an article on the uniform growth of a metal-organic framework, ZIF-8, on the surface of individual cellulose nanocrystals (CNCs). After the ZIF-8/CNC fibers had been coated with a microporous organic polymer, the ZIF-8 was removed to leave a microporous polymer with CNCs encapsulated in a ship-in-a-bottle architecture. This material proved to be effective for CO2 fixation. "Uniform Growth of Nanocrystalline ZIF-8 on Cellulose Nanocrystals: Useful Template for Microporous Organic Polymers", K. Cho, L. J. Andrew, M. J. MacLachlan, Angew. Chem. Int. Ed. 2023, e202300960.

Multiscale kinetic modeling of biomass fractionation in an experiment: Understanding individual reaction mechanisms and cellulose degradation

To avoid over-consumption and wastage of virgin fibers, the quality of pulp products is as important as their productivity. To this end, both the quality and quantity of pulp should be considered together during the pulping processes. Multiple experimental studies have highlighted that maintaining a high degree of polymerization (DP) for cellulose microfibers in the wood chip ensures a good quality pulp product. However, in the pulping process, the applied reagents and severe conditions can cause a certain degree of cellulose degradation, accompanying unwanted lowering of fiber grades. In order to mitigate cellulose degradation during this step, it is crucial to control the process conditions such as reagent concentration and temperature. Also, to establish the optimum operating strategies, it is necessary to understand how the operating conditions impact the DP of cellulose microfibers. Therefore, we have proposed a novel multiscale model which predicts mesoscopic properties (e.g., the lignin content and fiber morphology) alongside microscopic properties (e.g., the DP of the cellulose microfibers). The proposed model incorporates a multi-layered kinetic Monte Carlo (kMC) framework that allows us to capture the temporal evolution of lignin content, fiber morphology, and cellulose DP, occurring at disparate timescales, as a function of reaction conditions in a computationally tractable fashion. Furthermore, the model predictions are validated with the experimental results so that it gives us a detailed picture of the pulp production processes. Overall with the proposed model, we aim to maximize productivity and maintain a high quality of cellulose fibers from the wood chips during the pulping process.

Assessment of the optical properties with physicochemical properties and cell wall polysaccharides of ‘Korla’ pear flesh during Alternaria alternata-induced disease development

Cell wall polysaccharides and physicochemical properties are the major quality characteristics of fruit, but they are significantly affected by the postharvest disease. In this study, the influence of Alternaria alternata-induced disease on the contents of cell wall polysaccharides and physicochemical properties in ‘Korla’ pear flesh during storage, as well as their relationships of the optical absorption (μa) and reduced scattering (μs') were explored. The infected pear had lower individual sugars, covalent-soluble pectin, cellulose and hemicellulose contents than the healthy ones. The successive decreases of μa and increases of μs' in pears were observed while the process of pathogen infection. Path-coefficient analysis indicated the ionic-soluble pectin was the main reason responsible for the change of μs' in infected pear at 675 nm and 980 nm. This study indicated the optical properties have the possibility to present the physicochemical characteristics and cell wall polysaccharides of pears during postharvest pathogen infection.

Comparison of the Carbon Payback Period (CPP) of Different Variants of Insulation Materials and Existing External Walls in Selected European Countries

The EU “Fit for 55” legislative package provides for the introduction of regulations enabling the achievement of the emission reduction target by 55%. As part of the necessary actions, it is necessary to increase the energy efficiency of existing buildings. To achieve this, there are plans to increase the pace of the modernization of buildings, from 1% to 3% of buildings annually by 2030. However, this must be done with respect to the principles of sustainable development, circular economy and the conservation of buildings. This article presents a comprehensive comparison and calculation of carbon payback period (CPP) for selected insulation materials, combined with selected typical building partitions, and shows how quickly the payback period of greenhouse gases in the production of insulation materials is completed. Individual insulation materials (stone and glass wool, expanded polystyrene (EPS), extruded polystyrene (XPS), polyurethane (PUR) and cellulose) were analyzed in relation to different types of walls (seven types—including solid wall, diaphragm wall, large panel system (LPS), and concrete), in different locations (Poland, Germany, Czech Republic, Austria, Finland, Europe) and for various energy sources (electricity, gas, oil, biomass, district heating). After taking into account the carbon footprint embodied in the insulation materials, along with the potential reductions in the operational greenhouse gases emissions, the carbon payback period (CPP) was determined, resulting from the use of a given technology, insulation material and location. By comparing the CPPs for different insulations, this paper shows that the results vary significantly between EU countries, which have different embodied carbon factors for energy sources and materials, and that there is still a serious lack in the availability of reliable environmental information, which can limit research results.

A method for addressing compensation effect in determining kinetics of biomass pyrolysis

Compensation effect is an unsolved issue when determining pyrolysis kinetics of biomass using inverse modelling and optimization algorithms, implying no unique solution can be obtained. To address this problem, a new method coupling Gauss multi-peak fitting method, Kissinger method, a numerical model, and Shuffled Complex Evolution (SCE) optimization algorithm is proposed to extract kinetics from microscale thermogravimetric analysis (TGA) experiments and avoid attainment of unreasonable good-fit solutions. TGA tests of beech wood at nitrogen atmosphere were conducted at three heating rates. Gauss multi-peak fitting method was employed to separate the overlapped peaks in TGA curves and identify the contribution of each elemental component reaction. The kinetics of individual reactions were estimated by Kissinger method to provide an initial solution for SCE optimization. Then, narrow initial search ranges were determined to further refine the kinetics by SCE. By compiling previous data in literature and our optimization results, it was found compensation effect exists for individual basic components, hemicellulose, cellulose and lignin, following a linear correlation between lnA andEa, and among multiple components. Pyrolysis of hemicellulose can be modelled by either first-order or high-order reactions, while cellulose pyrolysis is more likely a first-order reaction. Nevertheless, the long tail in DTG curves associated with decomposition of lignin can only be captured by a high-order reaction. Although the Kissinger solution of lignin cannot be used in selecting an appropriate search range for SCE optimization, the narrow search ranges of the remaining kinetic parameters can ensure the accuracy and convergency efficiency of optimization.

Elucidating the fine-scale structural morphology of nanocellulose by nano infrared spectroscopy

Nanoscale infrared (IR) spectroscopy and microscopy, enabling the acquisition of IR spectra and images with a lateral resolution of 20 nm, is employed to chemically characterize individual cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) to elucidate if the CNCs and CNFs consist of alternating crystalline and amorphous domains along the CNF/CNC. The high lateral resolution enables studies of the nanoscale morphology at different domains of the CNFs/CNCs: flat segments, kinks, twisted areas, and end points. The types of nanocellulose investigated are CNFs from tunicate, CNCs from cotton, and anionic and cationic wood-derived CNFs. All nano-FTIR spectra acquired from the different samples and different domains of the individual nanocellulose particles resemble a spectrum of crystalline cellulose, suggesting that the non-crystalline cellulose signal observed in macroscopic measurements of nanocellulose most likely originate from cellulose chains present at the surface of the nanocellulose particles.

Molecular insights on the crystalline cellulose-water interfaces via three-dimensional atomic force microscopy.

Cellulose, a renewable structural biopolymer, is ubiquitous in nature and is the basic reinforcement component of the natural hierarchical structures of living plants, bacteria, and tunicates. However, a detailed picture of the crystalline cellulose surface at the molecular level is still unavailable. Here, using atomic force microscopy (AFM) and molecular dynamics (MD) simulations, we revealed the molecular details of the cellulose chain arrangements on the surfaces of individual cellulose nanocrystals (CNCs) in water. Furthermore, we visualized the three-dimensional (3D) local arrangement of water molecules near the CNC surface using 3D AFM. AFM experiments and MD simulations showed anisotropic water structuring, as determined by the surface topologies and exposed chemical moieties. These findings provide important insights into our understanding of the interfacial interactions between CNCs and water at the molecular level. This may allow the establishment of the structure-property relationship of CNCs extracted from various biomass sources.

Toward stretchable batteries: 3D-printed deformable electrodes and separator enabled by nanocellulose

The needs for stretchable batteries surge as wearable and epidermal electronics emerge. The development of stretchable batteries, however, remains a grand challenge, as the battery components are intrinsically brittle and fracture easily under mechanical loading. Existing efforts to increase the stretchability of battery components often involve complex fabrication processes and thus are not viable for scalable and cost-effective manufacturing. To address this challenge, herein a facile yet effective strategy is developed to fabricate stretchable electrodes and separator for Li-ion batteries using extrusion-based 3D printing of active materials mixed with nanofibrillated cellulose. The resulting electrodes and separator can achieve reversible stretchability of 50%. After 50 stretching cycles, the resistance of the electrodes under 50% stretch only increases by 3%. The origin of the exceptional mechanical and electrical performances of the 3D-printed battery components is twofold: (i) excellent deformability enabled by the 3D-printed serpentine structure at the component level; (ii) the robust nanoscale structure due to the high aspect ratios of nanofibrillated cellulose and carbon nanotubes and the strong interactions between nanofibrillated cellulose and carbon nanotubes or among the individual cellulose fibers at the material structure level. The facile 3D printing of the patterned electrodes/separator leads to low-cost manufacturing of high-performance stretchable Li-ion batteries, demonstrating its promising potential to enable stretchable energy storage devices for wearable and epidermal electronics.

Deswelling of microfibril bundles in drying wood studied by small-angle neutron scattering and molecular dynamics

Structural changes of cellulose microfibrils and microfibril bundles in unmodified spruce cell wall due to drying in air were investigated using time-resolved small-angle neutron scattering (SANS). The scattering analysis was supported with dynamic vapor sorption (DVS) measurements to quantify the macroscopic drying kinetics. Molecular dynamics (MD) simulations were carried out to aid in understanding the molecular-level wood-water interactions during drying. Both SANS experiments and simulations support the notion that individual cellulose microfibrils remain relatively unaffected by drying. There is, however, a significant decrease in fibril-to-fibril distances in microfibril bundles. Both scattering and DVS experiments showed two distinct drying regions: constant-rate drying and falling-rate drying. This was also supported by the MD simulation results. The shrinking of the fibril bundles starts at the boundary of these two regions, which is accompanied by a strong decrease in the diffusivity of water in between the microfibrils.Graphic abstract

Levoglucosan Emission From Different Indigenous and Exotic Plant Species in Bangladesh

Levoglucosan is a biomarker for biomass burning with high emission efficiency. Both indigenous and exotic plant species (biomass) are common in Bangladesh and used as a fuel source in rural areas for cooking purposes. Three indigenous plants, Mango (Mangifera indica), Jackfruit (Artocarpus heterophyllus), Coconut (Cocos nucifera) and three exotic plants, Mahogany (Swietenia mahagoni), Koroi (Albizia lebbeck), Guava (Psidium guajava), were selected for this experiment. The study was carried out to determine and compare the levoglucosan emission for these selected indigenous and exotic plants upon burning at the typical rural cooking stove in the laboratory scale. PM10 samples were collected on top of the cooking stove using a low volume air sampler (LVAS). The concentration was determined quantitatively by UV-visible spectrophotometer using anthrone-sulfuric acid reagent. The exotic plant samples (7.47 mg/m3) emitted a higher concentration of levoglucosan than the indigenous plant samples (6.49 mg/m3). Among the six different leaf samples, S. mahagoni leaves showed the highest emission of levoglucosan (6.31 mg/m3) and C. nucifera leaves showed the lowest levoglucosan (5.74 mg/m3) due to their individual cellulose content and combustion efficiency. Among the six wood samples, S. mahagoni woods showed the maximum concentration (9.63 mg/m3) and C. nucifera coir showed the minimum concentration (6.631 mg/m3) of levoglucosan emission. The soft leaf samples (6.02 mg/m3) showed lower emission than the hardwood (7.97 mg/m3) samples because of their diverse structural pattern and combustion efficiency. Comparing the emission factors, the exotic wood and leaf samples (EF=2.89*10– 3g/kg) showed higher emission than the indigenous wood and leaf samples (EF=2.55*10–3g/kg) J. Biodivers. Conserv. Bioresour. Manag. 2020, 6(2): 1-10