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Growing demand for animal products caused by a growing population and improved living-standards also yields large quantities of manure constituting an eminent problem. Herbivore manure can be utilized as fertilizer or for biogas production, which, however, disregards the full potential of manure as feedstock for lignocellulosics. Thus, an integrated process combining biogas production and isolation of natural fibres next to providing fertilizer precursors would constitute a major leap forward.

Funding Information: The authors acknowledge Tiergarten Schönbrunn for providing the elephant manure, Johannes Theiner from the Microanalytical Laboratory (Faculty of Chemistry) at the University of Vienna for performing elemental analysis and IR-spectroscopy, and the following students for their help with various aspects of the work: Alexander Blocher, Lisa Panzenböck, Hanna Hirn, Nina Troppmaier, Manuel Holzman (all University of Vienna), and Elodie Schaffner (Institut National Polytechnique de Toulouse). The authors also thank Stephan Puchegger from the Faculty Center for Nano Structure Research for his help with the SEM and Antje Potthast (Institute of Chemistry of Renewable Resources, University of Natural Resources and Life Sciences, Vienna) for measuring the molecular weight of the cellulose. This work was supported by OeAD (WTZ ZA 03/2017) enabling the collaboration with CSIR, Port Elisabeth, South Africa. K.W. is grateful for the financial support provided by the Institute of Materials Chemistry of University of Vienna (371300). E.K. acknowledges the support by FinnCERES Materials Bioeconomy Ecosystem. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. The demand for animal products has significantly increased over the past decades as a result of the growing population and the heightened standards of living. Increased livestock farming does not only yield desired products but also significant quantities of wastes, particularly manure whose storage and application are being monitored with a tightening network of regulations. The problem is that manure is considered merely as a substrate for biogas production or as a fertilizer, whereas the substantial portion of fibers residing in herbivore manure has remained underutilized. Here, we propose a manure management system, in which not only biogas and fertilizer precursors but also high-value materials in the form of (nano)cellulose are produced. We show that high biogas yields can be achieved for elephant manure and the remaining substrate enables effortless isolation of cellulose nanofibers, leading to a significant reduction of the environmental impact compared with traditional systems based on wood.

The interfacial properties of carbon fiber (CF) reinforced thermoplastic composites depend strongly on the wettability and surface characteristics of the reinforcing fibers, and their compatibility with a chosen matrix. The interface between conventional fibers and thermoplastic matrices is generally weak, due to a lack of specific chemical interaction, especially in the case of polyolefins. Carbon nanotube-grafted-carbon fibers (CNT-g-CF) are considered to be potential reinforcements as they provide additional mechanical interlocking. Commercial CFs were successfully grafted with nanotubes using a continuous, and hence scalable, CVD method. X-ray photoelectron spectroscopy, Wilhelmy wetting measurements, and scanning electron microscopy confirmed the successful grafting and resulting hydrophobic surface chemistry, dominated by van der Waals interactions. The grafted CNTs, with diameters and lengths around 10 nm and 140 nm respectively, were well suited to improve the overall wettability and interfacial shear strength (+53.4 %) of the CNT-g-CF in a polypropylene matrix when compared to as-received unsized CFs.

We evaluated the influence of blending various renewable polymer grades and amounts to allow for high stretchability during stretching at 800 mm/s to produce polymer tapes with high Young’s moduli E and yield stress σy similar to industrial production of non-degradable synthetic polymers. Renewable polymer blends based on TPS, PBAT, and PLA with high stretchability as well as high E and σy of stretched tapes comparable to high-density polyethylene (PE-HD) and isotactic polypropylene were identified. High stretchability (up to 380%) was facilitated with TPS-PBAT tapes and comparably high E (up to 5000 MPa) and σy (up to 160 MPa) of stretched tapes were obtained for mixtures of different PLA grades resulting in E-moduli exceeding that of PE-HD. A balance of these properties approaching those of synthetic polymers was achieved with PLA-PBAT blends (stretchability: 340%, E: 4500 MPa, σy: 120 MPa).

The long-term drag reduction capability of poly(ethylene oxide) with a nominal molar weight of [Formula: see text] g/mol dissolved in water was investigated in a pilot-scale pipe flow device (inner diameter of test section 26 mm) at a Reynolds number of 105. A total loss of the initially high (75%) drag reduction capability was observed over a flow distance of several ∼10 km while the molar weight of the polymer was still [Formula: see text] g/mol. Mechanical degradation in the turbulent flow as well as ageing of the polymer dissolved in water caused this loss in drag reduction capability. A simple ansatz of two independent, statistical polymer chain scission mechanisms was used to describe the polymer degradation empirically using a modified Brostow model. This empirical description was applied successfully and suggested that the polymer exhibited at least 15 cleavage points for mechanical degradation.

The use of chemical and energy intensive delignification processes in industrial pulping generates cellulosic fibres that are hydrophilic, hygroscopic and functionally restricted to paper and cardboard applications. Here, we propose a bio-based alternative to chemical pulping utilising herbivores to harvest and grind lignocellulosic materials followed by natural fungal growth to delignify and hybridise them to generate hierarchical composite papers with altered, water-repelling surface properties. These papers comprise cellulose and fungal biopolymers produced by cultivation of T. versicolor and P. ostreatus on elephant manure. Papers with considerably more hydrophobic surfaces were obtained at glucosamine contents as low as 0.1 wt%. Paper tensile strengths and elastic moduli were improved with longer fungal growth periods, spanning several weeks, resulting in comprehensive interfacing of cellulose microfibrils through tough nanoscale fungal chitin-β-glucan networks within the papers. Papers produced from lignocellulosic material colonised with P. ostreatus for 16 weeks exhibited the highest tensile strengths and more hydrophobic surfaces than T. versicolor. Hybridisation of lignocellulose with fungal biopolymers resulting in improved surface and mechanical properties highlights the extended opportunities of fungal delignification bioprocessing and demonstrates the considerable potential of the fungal biorefinery as an economical, and as of yet underexploited technology.

Fungi-derived leather substitutes are an emerging class of ethically and environmentally responsible fabrics that are increasingly meeting consumer aesthetic and functional expectations and winning favour as an alternative to bovine and synthetic leathers. While traditional leather and its alternatives are sourced from animals and synthetic polymers, these renewable sustainable leather substitutes are obtained through the upcycling of low-cost agricultural and forestry by-products into chitinous polymers and other polysaccharides using a natural and carbon-neutral biological fungal growth process. Following physical and chemical treatment, these sheets of fungal biomass visually resemble leather and exhibit comparable material and tactile properties. Fungi-derived material can substitute for leather. This Review synthesizes information on this process and its environmental and ethical benefits.

The abstract is available here: https://uscholar.univie.ac.at/o:1624880

Uncured solid bisphenol-A epoxy resins containing up to 20 wt% carbon nanotubes (CNTs) were prepared using melt blending in a high shear mixer. The extrudate was ground to produce fine nanocomposite (NC) powders. This simple method produced well-dispersed NC, with CNT agglomerate sizes below 1 μm. Consolidated NCs displayed improved tensile moduli and strengths up to 3.3 GPa (+32%) and 78 MPa (+19%), respectively at 15 wt% CNT, compared to the pure cured epoxy matrix. The relatively high Tg of 39 ◦C for the uncured NC powders simplified the manufacture of composite prepregs using wet powder impregnation. The prepregs were laminated into hierarchical carbon fibre reinforced composites with improved through-thickness properties. Interlaminar shear strength improved for intermediate CNT loadings in the matrix up to 65 MPa (10 wt% CNT, +19%) but decreased at higher concentrations. Compression moduli remained constant irrespectively of CNT loading but compression strength increased with a CNT loading of 2.5 wt% to 772 MPa (+31%). The mechanical properties of the hierarchical composites reflect good consolidation (void content

A tubular co-flow reactor to produce macroporous polymer beads by polymerization of medium and high internal phase emulsion (M/HIPE) templates was developed. This reactor allows for improved production rates compared to tubing based microfluidic devices. Water-in-oil (W/O) M/HIPEs, containing methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) monomers in the continuous phase, were injected into a re-circulating carrier phase. The continuous phase of the emulsion droplets was UV polymerized in situ, resulting in polyM/HIPE beads. The emulsion composition was adjusted to produce poly(MMA-co-EGDMA) porous polymer beads with a protective crust and an interconnected internal pore structure. HCl loaded beads were produced by adding the active ingredient into the dispersed emulsion phase, leading to HCl encapsulation in the porous structure of the beads after polymerization. Even after exposure to ambient conditions for 24 h, 60% of the HCl remained in the beads, indicating good encapsulation efficiencies. Thus, it is possible to use such macroporous beads as delivery vehicles.

Treatment of polluted water is an important task to secure access to clean water also for future generations. Filters are an efficient means to reject various pollutants on a wide range of size scales either by size-exclusion or electrostatic interaction, respectively. Commonly, filters and membranes from various synthetic materials are employed for these applications. Recently, filters based on renewable (nano) cellulose papers and coatings emerged as sustainable alternative to synthetic materials usually utilized. However, fabrication of such paper network structures from aqueous suspension by filtration processes is a time-consuming process caused by the high water holding capacity of highly hydrophilic and negatively charged nanocellulose fibrils. To optimize the preparation of nanocellulose coated filters, substitution of water by air and thus generating nanocellulose foams that are collapsed onto a substrate would be an appealing approach. Here we present the development of foams from negatively charged TEMPO-oxidized nanocellulose by screening various surfactants and concentrations to generate a foam stable enough to be transferred onto a viscose substrate. Foams were collapsed by oven consolidation, positive pressure filtration, or hot-pressing, respectively. Consolidated filters were tested for their water permeance and rejection of heavy metal ions using copper ions as model system. Very high permeances competitive to commercial filters based on synthetic polymers were achieved. Furthermore, adsorption capacities for copper of up to 70 mg/g were found. This is close to adsorption capacities reported for negatively charged TEMPO-oxidized nanocellulose in conventional batch-wise static adsorption. However, in the current process adsorption takes place during filtration of water through filters in a continuous process which constitutes a tremendous advantage. Graphical Abstract

Investigations on lithographically formed cavities of surface-imprinted polymers (SIP) can help to gain deeper understanding on cell recognition with SIPs: it is known that surface topography and biomolecules transferred during surface imprinting contribute to cell adhesion. In this work, SIPs synthesized

Micromixers made from emulsion templated macroporous polymers (poly-Pickering-HIPEs) were used to continuously produce polymerizable high internal phase emulsions (HIPE) by injecting a monomer containing continuous phase and aqueous internal phase into micromixers. The interconnected and complex flow path through poly-Pickering-HIPE micromixers resulted in effective mixing by creating local vortices and shear. The emulsion phase volume fraction of the produced HIPE templates can be varied during the process. PolyHIPEs with a porosity gradient ranging from 74% to 89% were produced by altering the phase volume ratio during the emulsification in poly-Pickering-HIPE micromixers. The average pore size of the produced polyHIPEs can be tailored by using poly-Pickering-HIPE micromixers with degrees of interconnectivity ranging from 0.028 to 0.06. The lower the degree of interconnectivity of the micromixer the smaller the droplet size of the produced HIPEs and thus the average pore size of the resulting polyHIPEs.

Structural supercapacitors can both carry load and store electrical energy. An approach to build such devices is to modify carbon fibre surfaces to increase their specific surface area and to embed them into a structural electrolyte. We present a way to coat carbon fibres with graphene nanoplatelets by electrophoretic deposition in water. The effect of time and voltage on the mechanical properties of the carbon fibres, the structure of the coating and the specific surface area of the coated carbon fibres are discussed. A specific capacity of 1.44 F/g was reached, which is 130% higher than state-of-the-art structural electrodes. We demonstrate the scalability of the deposition process to continuous production of coated carbon fibres. These carbon fibre electrodes were used to realise large (21 cm long) structural supercapacitor demonstrators without the need for a separator, having a specific capacity of 623 mF/g.

There are a range of promising applications for devices that can convert mechanical energy from their local environment into useful electrical energy. Here, mechanical energy harvesting devices have been developed to scavenge low-frequency energy from regular biomotion such as joint movement and heel strike. Specifically, these harvesters exploit novel printed nanocomposite dielectric inks in combination with commercially available conductive elastomers to develop a low cost, high performance embodiment of a variable capacitance mechanism device. The filler of the nanocomposite dielectric ink, consists of high-k dielectric nanoparticles (barium titanate and strontium doped barium titanate) functionalised with poly(methyl methacrylate) to improve the interface with the epoxy matrix. Characterisation by thermogravimetric analysis coupled to mass spectrometry and X-ray photoelectron spectroscopy confirmed the successful covalent grafting of up to ca. 16 wt% poly(methyl methacrylate) onto the dielectric nanoparticle surfaces, with a thickness of approximately 14 nm, measured by transmission electron microscopy. The dielectric inks were screen printed onto copper-polyimide foils, resulting in large area and flexible five to twenty-micron thick films with dielectric constants up to 45. Nanoparticle polymer functionalisation improved the homogeneity and stability of the inks. Using these screen-printed dielectrics with the commercial conductive elastomer, the mechanical energy harvester prototype demonstrated high mechanical cycling stability and low leakage current. It provided a promising power density of 160 μW cm-3, at low frequency (0.5 Hz), over a 1000 cycles, making the device suitable for wearable applications. This type of harvester has two advantages over the state of the art: it is mechanically flexible for integration into wearables and can be produced at low cost with printing methods. This journal is

The abstract is available here: https://uscholar.univie.ac.at/o:1633047

Due to its unique properties, nano fibrillated cellulose (NFC) has been a popular topic of research in recent years. Nevertheless, literature assessing environmental impacts of NFC production is scarce, especially for using other starting materials than wood pulp. Hence, in this study, a new approach of cascaded use of manure to produce biogas and subsequently use the cellulose containing digestate for NFC production (manure scenario) is compared to the production from Kraft pulp from hardwood chips (wood chips scenario) via life cycle assessment (LCA). To produce comparable outputs (NFC and biogas) in both scenarios a typical Austrian biogas plant with maize silage and pig slurry as input material is included in the wood chips scenario. A proxy approach is used to upscale the manure scenario from laboratory to an industrial scale (except for the pulp to NFC step) to ensure comparability of both scenarios. The impact categories global warming potential (GWP), fossil resource scarcity, freshwater eutrophication, human toxicity, terrestrial acidification (TAP) and terrestrial ecotoxicity potential are analysed referring to the functional unit of 1 kg NFC. Results show that the manure scenario has at least 45% lower impacts in all assessed categories. GWP is 4.41 kg CO

Birch (Betula pendula Roth.) and beech (Fagus sylvatica L.) solid wood and plywood were overmolded with polyamide 6 (PA 6) and polypropylene (PP) to investigate their mechanical properties and interfacial adhesion. In the case of PA 6, maximum tensile shear strengths values of more than 8 to 9 MPa were obtained for birch and beech, respectively. The values are comparable to bond strengths of commercial joints bonded with formaldehyde-containing amino-plastics. Perpendicular to the wood elements, bond strength values of 3 MPa was achieved for PA 6. The penetration of the polymers into the wood structure results in a non-densified interphase and subsequent plastic deformation of the wood structure beyond the interphase. These compressed areas influenced the interfacial adhesion and mechanical interlocking. SEM and XPS analysis revealed different interpenetration behavior of the polymers into the wood structure, with chemical interaction confirmed only for wood and PA 6 but not PP.

The abstract is available here: https://uscholar.univie.ac.at/o:1641772

Funding Information: KSK and AB acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) (EP/K014676/1). KSK also acknowledges Academy of Finland (Project number 310943). EK is grateful for the support by the FinnCERES Materials Bioeconomy Ecosystem. Funding Information: Open access funding provided by Aalto University. KSK and AB acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) (EP/K014676/1). KSK also acknowledges Academy of Finland (Project number 310943). Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Cellulose nanopapers provide diverse, strong and lightweight templates prepared entirely from sustainable raw materials, cellulose nanofibers (CNFs). Yet the strength of CNFs has not been fully capitalized in the resulting nanopapers and the relative influence of CNF strength, their bonding, and biological origin to nanopaper strength are unknown. Here, we show that basic principles from paper physics can be applied to CNF nanopapers to illuminate those relationships. Importantly, it appeared that ~ 200 MPa was the theoretical maximum for nanopapers with random fibril orientation. Furthermore, we demonstrate the contrast in tensile strength for nanopapers prepared from bacterial cellulose (BC) and wood-based nanofibrillated cellulose (NFC). Endemic amorphous polysaccharides (hemicelluloses) in NFC act as matrix in NFC nanopapers, strengthening the bonding between CNFs just like it improves the bonding between CNFs in the primary cell wall of plants. The conclusions apply to all composites containing non-wovenfiber mats as reinforcement.

Greener alternatives to synthetic polymers are constantly being investigated and sought after. Chitin is a natural polysaccharide that gives structural support to crustacean shells, insect exoskeletons, and fungal cell walls. Like cellulose, chitin resides in nanosized structural elements that can be isolated as nanofibers and nanocrystals by various top-down approaches, targeted at disintegrating the native construct. Chitin has, however, been largely overshadowed by cellulose when discussing the materials aspects of the nanosized components. This Perspective presents a thorough overview of chitin-related materials research with an analytical focus on nanocomposites and nanopapers. The red line running through the text emphasizes the use of fungal chitin that represents several advantages over the more popular crustacean sources, particularly in terms of nanofiber isolation from the native matrix. In addition, many β-glucans are preserved in chitin upon its isolation from the fungal matrix, enabling new horizons for various engineering solutions.

The influence of the crystallization temperature and the pressure on the crystallization kinetics, structure and compression strength of γ-polypropylene was investigated. Samples were produced in a custom-made high-pressure crystallization cell and characterized by differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). It could be shown that the strength is mainly affected by the mean lamellar thickness. The strength of γ-PP is at least 40% higher than α-PP at the same mean lamellar thickness. This confirms the hypothesis that the arrangement of non-parallel chains restricts the number of possible slip systems so that almost no mobile dislocations are generated. The mode of nucleation is only slightly affected by the crystallization pressure. The Avrami coefficient is n = 2.5 ± 0.1 at the beginning of crystallization and largely independent of pressure.

Contamination of fresh water sources with heavy metal ions constitutes a serious threat to drinking water safety. Treatment of water in order to remove these contaminants, e.g. copper ions, is thus an important task, usually performed by utilizing adsorbents or continuous membrane/filter processes. In particular combinations of these processes, i.e. adsorption or ion-exchange membranes/filters, are potential solutions in this regard. Thereby, materials derived from renewable resources constitute an environmentally benign alternative to traditional adsorption membrane/filter materials. For example, anionic TEMPO-oxidized cellulose nanofibrils (TCNF) were demonstrated to have high affinity towards heavy metal ions but nanopaper membranes made thereof suffer from low permeance and hence limited performance. To achieve high permeance and efficient adsorption of metal ions utilizing pure nanopapers has still not been possible. However, decorating a porous natural fibre substrate with TCNF should allow for high adsorption capacity towards Cu2+ together with high water permeance. We here present natural fibre-nanocellulose composite filters derived from flax and agave fibres, extracted e.g. from tequila residues, decorated with TCNF. The performance of these filters was determined with respect to their permeance and adsorption capacity for copper. It was shown that this new type of filter derived from industrial crop residues is capable of adsorbing high amounts of Cu(II) ions during a continuous filtration process with very high permeances enabled by their highly porous nature.

Agricultural by-products can be upcycled into environmentally-sustainable, inexpensive chitinous materials and nanofibers derived from fungal mycelium for composites, cosmetics, pharmaceuticals and water treatment applications. This study determined the suitability of common agricultural by-products as medium for fungal growth. Growth was measured by quantifying ergosterol, a unique fungal product, in solid and liquid media. The results reveal that fungi grew less on rice hull, sugarcane bagasse and wheat straw agricultural by-products than on commercial wheat grains. However, the liquid agricultural by-product blackstrap molasses facilitated very high biomass production, outperforming the commonly used laboratory nutrient malt extract. Hyphal fusion, sheet formation and hyphal diameter metrics of fungi growing on each substrate were evaluated by SEM to assess suitability for chitin nanofiber production. Utilising these materials offers a cheap, renewable, easily-isolated, and abundant alternative to problematic crustacean chitin that when implemented on a large scale could rapidly upcycle low-value agricultural by-products into high-value chitinous materials.

Polyimides (PI) generally have a high affinity for single-walled carbon nanotubes (SWNTs), but they suffer from poor solubility in most low boiling point organic solvents and low compatibility with common resins (such as epoxy) used in composites, limiting their suitability as dispersants. PI block copolymer systems containing reactive poly(ester carbonate)s have not yet been reported and are expected to act as effective reactive dispersing agents of SWNTs. Herein, PI-derived block copolymers are synthesized via ring-opening copolymerization of lactide (LA) (a control monomer) and allyl-bearing 2-methyl-2-(allyloxycarbonyl)-propylene carbonate (MAC) from the OH-terminal ends of the PI block to produce PLA-PI-PLA (TB1, a control) and PMAC-PI-PMAC (TB2). The allyl pendant group of TB2 allows further facile functionalization to form a third series of epoxidized (EP) derivatives, i.e. PMACEP-block-PI-block-PMACEP (TB3). TB3 copolymer when mixed with a conventional structural epoxy resin forms blends that do not show inferior tensile properties compared with the epoxy, which is unusual. Furthermore, the mixing solvent tetrahydrofuran (THF) can be readily evaporated off after forming the blends. TB3-dispersed (2 wt%) SWNTs added to epoxy increased the tensile strength, modulus, and elongation at break of the resulting nanocomposite films by 40%, 34%, and 26% respectively, compared to the baseline epoxy resin. Furthermore, when TB3b triblock-dispersed SWNTs in epoxy were combined with fuzzy carbon fibers, i.e. carbon nanotube-grafted-carbon fibers (CNT-g-CF), a synergistic interfacial strength reinforcement was observed, together with shifting of the failure mode from the matrix interphase to the carbon fiber-grafted nanotube interface. The ultimate interfacial shear strength between the TB3-dispersed SWNT-epoxy matrix and the fuzzy carbon fibers (i.e., fibers having carbon nanotubes grown on them) measured via single fiber pull-out tests was 100 MPa, which was ca. 11% improvement over the baseline unsized carbon fiber in neat epoxy. To our knowledge, this is the first evidence of a synergistic enhancement in interfacial properties when fuzzy carbon fibers are combined with a SWNT-reinforced epoxy using the new epoxidized TB3 nanotube dispersing agent that forms a strong covalent TB3–epoxy interface. The new functionalizable TB3 synthesis route introduced here is generalizable to other PI-based copolymers with diverse functionalities and solvent compatibilities. ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore) NMRC (Natl Medical Research Council, S’pore) MOH (Min. of Health, S’pore) Accepted version

An isolation method with mild mechanical agitation and no acidic extraction step from a mushroom substrate resulted in chitin nanofibers (ChNFs) with large shares of retained glucans (50-65%). The subsequent chitin nanopapers exhibited exceptionally high tensile strengths of >200 MPa and moduli of ca. 7 GPa, which were largely attributed to the preserved glucans in the mixture, imparting a composite nature to the nanopapers. The isolation method for ChNFs is notably different from the conventional process with crustacean chitin sources that do not incorporate glucans and where an acidic extraction step for the removal of minerals must always be included.

By whipping air into a solution containing the pulp processing by-product black liquor, crosslinker and surfactant, stable air-in-black liquor froths were produced. The air volume in the froths was controlled by tuning the viscosity of the black liquor and the whipping time. By the selectively crosslinking the renewable lignin and hemicellulose content in the black liquor froths, lignin foams possessing a porosity of up to 88% have been produced. The porosity, pore and pore throat sizes decreased with increasing viscosity of the continuous liquid phase of the black liquor froths. The resulting lignin foams were pyrolysed to produce renewable carbon foams, which retained the shape and macropore structure of the lignin foam precursor well, opening the door to structurally designable carbon foams from lignin. The work demonstrated that froth templating using an industrial by-product is a viable low-cost method to produce both stable lignin and carbon foams.