535 results found
Verdross P, Guinchard S, Woodward RT, et al., 2023, Black liquor-based epoxy resin: Thermosets from untreated kraft lignin, Chemical Engineering Journal, Vol: 475, ISSN: 1385-8947
The production of thermosetting resins from lignin is a promising route to upcycle this biomaterial, currently overwhelmingly used as fuel. Raw kraft black liquor with no prior purification or treatment was derivatised using epichlorohydrin and an aniline catalyst to yield a black liquor-based epoxy resin (BLER). BLER is a liquid resin, which can be processed using conventional moulding techniques prior to curing into black liquor-based thermosets using maleic anhydride as hardener. We report the production of liquid lignin-based thermosets containing a biocarbon content of ∼ 16%. These thermosets possess Young's moduli and tensile strengths exceeding 1 GPa and 40 MPa, respectively. The chemical composition of the starting material and BLER were characterised, and the mechanisms of cure as well as the mechanical properties of lignin-based thermosets were determined.
Hubert O, Todorovic N, Rojas González LM, et al., 2023, Sulfonated hypercrosslinked polymer enhanced structural composite supercapacitors, Composites Science and Technology, Vol: 242, ISSN: 0266-3538
Structural supercapacitors are multifunctional devices able to bear mechanical load while storing electrical energy. Carbon fibres can be used as a bifunctional component within structural supercapacitors, acting both as current collector and mechanical reinforcement. A promising route to such devices is to increase the surface area of carbon fibres, which can be achieved by the deposition of active materials, and embed them into a structural electrolyte. A highly sulfonated, high porosity hypercrosslinked polymer was deposited onto carbon fibres by electrophoretic deposition from an aqueous suspension. We investigated the effect of polymer and binder concentration in the deposition suspension on the electrochemical properties of the coated carbon fibre electrodes. Multifunctional structural composite supercapacitors had a fibre volume fraction of only 21% and possessed a tensile strength and Young's modulus of 495 MPa and 49 GPa, respectively. A specific capacitance of 1.2 F/g was reached, comparable to graphene coated carbon fibre electrodes. At room temperature and ambient humidity an energy density of 39 mWh/kg and a power density of 15 W/kg were measured. We demonstrate that moisture plays a major role in the energy storage mechanism in these SCs.
Woodward RT, Bismarck A, 2023, Where porous polymers can make a difference, Express Polymer Letters, Vol: 17, Pages: 771-772, ISSN: 1788-618X
Naghilou A, Peter K, Millesi F, et al., 2023, Insights into the material properties of dragline spider silk affecting Schwann cell migration., Int J Biol Macromol, Vol: 244
Dragline silk of Trichonephila spiders has attracted attention in various applications. One of the most fascinating uses of dragline silk is in nerve regeneration as a luminal filling for nerve guidance conduits. In fact, conduits filled with spider silk can measure up to autologous nerve transplantation, but the reasons behind the success of silk fibers are not yet understood. In this study dragline fibers of Trichonephila edulis were sterilized with ethanol, UV radiation, and autoclaving and the resulting material properties were characterized with regard to the silk's suitability for nerve regeneration. Rat Schwann cells (rSCs) were seeded on these silks in vitro and their migration and proliferation were investigated as an indication for the fiber's ability to support the growth of nerves. It was found that rSCs migrate faster on ethanol treated fibers. To elucidate the reasons behind this behavior, the fiber's morphology, surface chemistry, secondary protein structure, crystallinity, and mechanical properties were studied. The results demonstrate that the synergy of dragline silk's stiffness and its composition has a crucial effect on the migration of rSCs. These findings pave the way towards understanding the response of SCs to silk fibers as well as the targeted production of synthetic alternatives for regenerative medicine applications.
Kondor A, Burnett DJ, Bismarck A, et al., 2023, Correct specific retention volume determination in inverse gas chromatography., J Chromatogr A, Vol: 1700
Inverse Gas Chromatography (IGC) is an important technique for characterization of solids. Determining the specific retention volume of the injected probe molecule is the basis of the analysis for all the physico-chemical properties that the technique can determine, most importantly in Heat of Sorption, Glass Transition Temperature, Gibbs Adsorption Free Energy. Two equations have been used in the literature to calculate the specific retention volume; one normalizes the retention volume to 0 °C (standard temperature), which was previously proven to be thermodynamically incorrect, while the other calculates the retention volume at the measurement temperature. Here, we compare the heat of sorption for a series of alkanes on two substrates, micro crystalline cellulose and natural graphite, calculated using these two equations. This study shows that the specific retention volume is strongly dependent on the column temperature. Using the retention volume values normalised to 0 °C consistently overestimates the heats of sorption by up to 10%. Most importantly, correcting the retention volume to standard temperature will misrepresent the effect of temperature on the retention volume and the thermodynamic parameters derived from it.
Rusakov D, Menner A, Bismarck A, 2023, High Porosity Poly(ether ketone ketone): Influence of Solvents on Foam Properties, Macromolecular Materials and Engineering, Vol: 308, ISSN: 1438-7492
Poly(ether ketone ketone) (PEKK) is a semicrystalline high-performance polymer with exceptional mechanical properties, high continuous operation temperature, and is insoluble in most common solvents. Porous PEKK, desired for biomedical applications, is produced by a high-temperature thermally induced phase separation process using PEKK solutions in two high boiling aprotic solvents, 4-phenylphenol and 9-fluorenone, with concentrations up to 20 wt.%. It is demonstrated that the solvent choice has a pronounced influence on the phase separation behavior, which determines the foam morphology, physical and mechanical properties of PEKK foams. Porous PEKK with porosities ranging from 70% to 90%, specific surface areas up to 194 m2 g−1 and elastic moduli ranging from 35 to 100 MPa are produced.
Muratspahić E, Schöffmann J, Jiang Q, et al., 2023, Poly(acrylamide-co-styrene): A Macrosurfactant for Oil/Water Emulsion Templating toward Robust Macroporous Hydrogels, Macromolecules, Vol: 56, Pages: 3213-3223, ISSN: 0024-9297
Large amounts of relatively expensive small-molecule surfactants, between 6 and 25%, are typically required for the formulation of oil/water high or medium internal phase emulsion (H/MIPE) templates. We synthesized an amphiphilic “macrosurfactant” copolymer poly(acrylamide-co-styrene) via micellar polymerization. As-synthesized poly(acrylamide-co-styrene) still associated with 0.01 wt % cetyltrimethylammonium bromide (CTAB) can be used to produce stable toluene or cyclohexane-in-water H/MIPEs already at concentrations of 0.1 wt %. Emulsion templates containing 2-hydroxyethyl methacrylate (HEMA) and N,N-methylenebis(acrylamide) (MBAm) in the aqueous continuous phase can be polymerized to produce macroporous poly(HEMA-co-MBAm)M/HIPEs. Our poly(HEMA-co-MBAm)M/HIPEs synthesized in templates stabilized with much lower emulsifier content were mechanically more robust, in dry and swollen state, as compared with poly(HEMA-co-MBAm)HIPEs reported in the literature.
Anthony DB, Nguyen SN, Qian H, et al., 2023, Silica aerogel infused hierarchical glass fiber polymer composites, Composites Communications, Vol: 39, Pages: 1-7, ISSN: 2452-2139
Hierarchical systems can address the matrix-dominated failures of structural fiber polymer composites. Here, a new synergistic hierarchical structure combines conventional structural glass fibers with a bi-continuous silica-based aerogel matrix; both pure-silica and organically-modified silicate aerogels are demonstrated. When infused with an epoxy matrix, this type of hierarchical architecture showed a marked improvement in mechanical properties: without any loss in modulus, both the compressive strength and the interlaminar shear strength increased by up to 27%, relative to the equivalent glass-fiber reinforced epoxy composite baseline. The bi-continuous network modification strategy uses industrially-relevant infusion techniques, at or near room temperature, and retains a similar final composite density (within 2%). The strategy presented here provides a versatile and readily applicable means to improve state-of-the art continuous fiber reinforced composite systems in compression and offers an opportunity to develop a new generation of composite materials.
Weiland K, Alge K, Mautner A, et al., 2023, Horse manure as resource for biogas and nanolignocellulosic fibres., Bioresour Technol, Vol: 372
Nanofibrillated cellulose (NFC) has key applications in composites, water filters and as emulsifiers. The affinity of NFC to water is a challenge, as it negatively influences its integrity. Lignin, a major component of plant biomass, is a natural hydrophobiser. Anaerobic digestion (AD) of biomass to produce biomethane allows to up-concentrate lignin in the fermentation residue containing lignocellulosic fibres. Horse manure was used as substrate for biogas production from which nanolignocellulose fibres (LCNF) were extracted. A biogas yield of 207 LN kgVS-1 with a methane concentration of 65 % was achieved. From the fermentation residue LCNFs, in yields of up to 41 %, with lignin contents between 23 and 29 wt% depending on fermentation time were obtained. Nanopapers produced from LCNFs possessed tensile strengths and moduli of 45 to 91 MPa and 7 to 8 GPa, respectively. The increased lignin content was responsible for decreased water absorption capacity of nanopapers.
Almousa H, De Luca H, Anthony D, et al., 2023, Robust continuous production of carbon nanotube-grafted structural fibres: a route to hierarchical fibre reinforced composites, ECCM20 - The 20th European Conference on Composite Materials, Publisher: Composite Construction Laboratory (CCLab), Pages: 1451-1456
Growth of carbon nanotubes (CNTs) onto the fibre surface by direct chemical vapour deposition (CVD) offers a convenient means to integrate synthesis with assembly. This method delivers the nanostructures where they have the greatest influence on fibre-matrix interface or interphase. However, CVD is usually limited to small batches of short fibre lengths, and can damage the primary properties. Here, we describe a robust process to produce carbon nanotube-grafted-fibres continuously at tow level with a uniform coverage of short (sub-500 nm length), 10-20 nm diameter CNTs. Different CNT growth conditions, such as temperature [650-950 °C], duration [0.72-50 min], line speed [0.6-10 m/h], potential difference [0-1000 V], and reactive gas flow/compositions were investigated. Following optimisation, the fabrication of an entirely “fuzzy” fibre reinforced hierarchical composite was achieved.
Mueller HW, Brandfellner L, Bismarck A, 2023, Long-term degradation of high molar mass poly(ethylene oxide) in a turbulent pilot-scale pipe flow, PHYSICS OF FLUIDS, Vol: 35, ISSN: 1070-6631
Mautner A, Wintner S, Weiland K, et al., 2023, Excellent excrements: Biogas and paper products made from animal manure, BioSpektrum, Vol: 29, Pages: 91-93, ISSN: 0947-0867
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.
Fortea-Verdejo M, Jiang Q, Bismarck A, et al., 2022, Foaming of oxidized nanocellulose for the preparation of high-flux water filters, MONATSHEFTE FUR CHEMIE, ISSN: 0026-9247
Muratspahic E, Brandfellner L, Schoeffmann J, et al., 2022, Aqueous Solutions of Associating Poly(acrylamide-co-styrene): A Path to Improve Drag Reduction?, MACROMOLECULES, Vol: 55, Pages: 10479-10490, ISSN: 0024-9297
Jiang Q, Horozov T, Bismarck A, 2022, One-pot approach to fabrication of porous polymers from Pickering emulsion templates, Polymer, Vol: 261, ISSN: 0032-3861
We demonstrate a simple, versatile one-pot approach for the preparation of particle stabilised soft templates and macroporous polymer materials from them. This approach allows for the rapid fabrication (in a few minutes rather than hours) of large amounts of Pickering emulsion templates by performing the synthesis of mineral nanoparticle stabilisers (e.g. CaCO3) and the emulsification in-one-go in a very efficient way. It is shown that by using suitable formulations a variety of emulsion templates with a range of monomers can be fabricated and solidified to produce macroporous materials with closed-cell, open-cell or hierarchical pore architectures. Due to its versatility and scalability, this approach could be potentially used for the production of macroporous materials for research and diverse industrial applications.
Jones MP, Murali GG, Laurin F, et al., 2022, Functional flexibility: The potential of morphing composites, Composites Science and Technology, Vol: 230, Pages: 1-12, ISSN: 0266-3538
From plants tracking the sun to the aerodynamics of bird wings, shape change is key to the performance of natural structures. After years of reliance on mechanical joints, human engineering now focuses on improving aerodynamic efficiency through smooth, full form changes in material geometry, achieved using technologies such as morphing composites. Promising improved power generation and efficiency in wind turbines and safer more sustainable aircraft and cars, these materials can achieve both large geometric changes with low energy requirements by cycling between several stable physical states and more gradual changes in geometry by exploiting coefficient of thermal expansion mismatch and structural anisotropy, shape memory polymers and 4D printing. The merits and limitations of these various shape change systems are the subject of extensive and ongoing academic research and both commercial and defence industry trials to improve the viability of these technologies for widespread adoption. Shape change capabilities are often associated with problems in material cost, mass, mechanical properties, manufacturability, and energy requirements. Nonetheless, the considerable and rapid advances in this technology, already resulting in successful trials in advanced civilian and military aircraft and high-performance cars, indicate that future research and development of this materials platform could revolutionise many of our most critical power generation, defence and transport systems.
Barkan-Oeztuerk H, Delorme J, Menner A, et al., 2022, Liquid-liquid extraction using combined hydrophilic-hydrophobic emulsion templated macroporous polymer micromixer-settlers, CHEMICAL ENGINEERING AND PROCESSING-PROCESS INTENSIFICATION, Vol: 181, ISSN: 0255-2701
Barkan-Ozturk H, Menner A, Bismarck A, et al., 2022, Simultaneous hypercrosslinking and functionalization of polyHIPEs for use as coarse powder catalyst supports, CHEMICAL ENGINEERING SCIENCE, Vol: 264, ISSN: 0009-2509
Jones MP, Krexner T, Bismarck A, 2022, Repurposing Fischer-Tropsch and natural gas as bridging technologies for the energy revolution, ENERGY CONVERSION AND MANAGEMENT, Vol: 267, ISSN: 0196-8904
Wang J, Anthony DB, Fuentes CA, et al., 2022, Wettability of carbon nanotube-grafted carbon fibers and their interfacial properties in polypropylene thermoplastic composite, Composites Part A: Applied Science and Manufacturing, Vol: 159, Pages: 1-10, ISSN: 1359-835X
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.
Yousefi N, Fisher SJ, Burgstaller C, et al., 2022, Hierarchical carbon fibre composites incorporating high loadings of carbon nanotubes, Composites Science and Technology, Vol: 222, ISSN: 0266-3538
Uncured solid bisphenol-A epoxy resins containing up to 20 wt% carbon nanotubes (CNTs) were prepared usingmelt 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 NCsdisplayed improved tensile moduli and strengths up to 3.3 GPa (+32%) and 78 MPa (+19%), respectively at 15wt% CNT, compared to the pure cured epoxy matrix. The relatively high Tg of 39 ◦C for the uncured NC powderssimplified the manufacture of composite prepregs using wet powder impregnation. The prepregs were laminatedinto hierarchical carbon fibre reinforced composites with improved through-thickness properties. Interlaminarshear strength improved for intermediate CNT loadings in the matrix up to 65 MPa (10 wt% CNT, +19%) butdecreased at higher concentrations. Compression moduli remained constant irrespectively of CNT loading butcompression strength increased with a CNT loading of 2.5 wt% to 772 MPa (+31%). The mechanical propertiesof the hierarchical composites reflect good consolidation (void content <3%) and excellent fibre alignment(<±0.8◦). In addition to the improved mechanical properties, incorporation of CNTs improved the through-thickness electrical conductivity up to 115 S/m
Krexner T, Bauer A, Zollitsch W, et al., 2022, Environmental life cycle assessment of nano-cellulose and biogas production from manure, JOURNAL OF ENVIRONMENTAL MANAGEMENT, Vol: 314, ISSN: 0301-4797
Barkan-Oeztuerk H, Menner A, Bismarck A, 2022, Polymerised high internal phase emulsion micromixers for continuous emulsification, CHEMICAL ENGINEERING SCIENCE, Vol: 252, ISSN: 0009-2509
Ferrer J, Jiang Q, Menner A, et al., 2022, An approach for the scalable production of macroporous polymer beads, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 616, Pages: 834-845, ISSN: 0021-9797
Werner M, Glueck MS, Braeuer B, et al., 2022, Investigations on sub-structures within cavities of surface imprinted polymers using AFM and PF-QNM, SOFT MATTER, Vol: 18, Pages: 2245-2251, ISSN: 1744-683X
Lamoriniere S, Jones MP, Ho K, et al., 2022, Carbon nanotube enhanced carbon Fibre-Poly(ether ether ketone) interfaces in model hierarchical composites, COMPOSITES SCIENCE AND TECHNOLOGY, Vol: 221, ISSN: 0266-3538
Wu R, Jones MP, Jiang Q, et al., 2022, Assessing shear, tensile and fracture properties of macroporous nanocomposites using the Arcan test, POLYMER TESTING, Vol: 107, ISSN: 0142-9418
Bai S, Jones MP, de Laclause TP, et al., 2022, Towards robust synchronous belts: influence of surface characteristics on interfacial adhesion, COMPOSITE INTERFACES, Vol: 29, Pages: 1145-1159, ISSN: 0927-6440
Leese HS, Tejkl M, Vilar L, et al., 2022, High-k dielectric screen-printed inks for mechanical energy harvesting devices, MATERIALS ADVANCES, Vol: 3, Pages: 1780-1790
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