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The chemical structure, polymer mobility and mechanical properties are studied for a cross-linked amorphous poly(ether urethane) (PU) from glass transition to rubber elasticity for juvenile dry samples and for water-saturated states after exposure to humid air (r.h. = 29, 67, 95, 100%) at 60∘C during 1 y of ageing. For saturated samples, network chain cleavage is the chemical ageing mechanism, but it is too weak and slow to affect on the physical properties significantly within 1 y. Water acts primarily in a physical manner. Within 1 d, H2O molecules replace part of the weak urethane H-bonds by H2O–urethane H-bonds and reduce all other physical interactions between network chains by solvating hydrophilic segments. Thus, the cooperative polymer mobility strongly amplifies: The gain of specific conformational entropy doubles across the caloric glass transition, which shifts by −17 K. A H2O concentration of only cH2O≈(0.4…0.5)cH2O,max suffices for the major part of these fast rearrangements. Some part of the water slowly forms (during 3–4 months) a finely dispersed water-rich mixed phase with the PU chains. Except the new phase, these molecular processes of physical ageing strongly affect the mechanical properties at damage-free deformation. For dry PU in the glass transition, the shear modulus, μrelaxed(T), after viscoelastic stress relaxation only depends on the deformation-induced entropy change—like in the rubber elastic state. Within one month, water drastically decreases the viscoelastic response, as expected for plasticisation. However, μrelaxed(T) slightly grows in wet PU. H2O molecules cause these opposite trends by boosting the cooperative mobility (i.e. extension of the accessible conformational space and entropy by reduction in energy barriers) and by occupation of free volume compartments. Water quickly reduces the fracture parameters by about 50%. We explain that embrittlement by the H2O-induced facilitation of cooperative network chain motions, which let fracture proceed with less energy. In summary, our findings provide a detailed conception of the molecular effects the H2O molecules have on the PU network, and they explain the consequences for the mechanical properties.

Constructing composite solid electrolytes (CSEs) integrating the merits of inorganic and organic components is a promising approach to developing high‐performance all‐solid‐state lithium metal batteries (ASSLMBs). CSEs are now capable of achieving homogeneous and fast Li‐ion flux, but how to escape the trade‐off between mechanical modulus and adhesion is still a challenge. Herein, a strategy to address this issue is proposed, that is, intercalating highly conductive, homogeneous, and viscous‐fluid ionic conductors into robust coordination laminar framework to construct laminar solid electrolyte with homogeneous and fast Li‐ion conduction (LSE‐HFC). A 9 µm‐thick LSH‐HFC, in which poly(ethylene oxide)/succinonitrile is adsorbed by coordination laminar framework with metal–organic framework nanosheets as building blocks, is used here as an example to determine the validity. The Li‐ion transfer mechanism is verified and works across the entire LSE‐HFC, which facilitates homogeneous Li‐ion flux and low migration energy barriers, endowing LSE‐HFC with high ionic conductivity of 5.62 × 10−4 S cm−1 and Li‐ion transference number of 0.78 at 25 °C. Combining the outstanding mechanical strength against punctures and the enhanced adhesion force with electrodes, LSE‐HFC harvests uniform Li plating/stripping behavior. These enable the realization of high‐energy‐density ASSLMBs with excellent cycling stability when being assembled as LiFePO4/Li and LiNi0.6Mn0.2Co0.2O2/Li cells. A thin laminar solid electrolyte can actualize the homogeneous and fast Li‐ion flux while also breaking the trade‐off between mechanical modulus and adhesion. The robust coordination laminar framework allows electrolytes to achieve a high Young's modulus against punctures. Viscous‐fluid ionic conductor confined in coordination laminar framework provides homogeneous and fast Li‐ion transport channels and adhesive contact with electrodes.

In this study, rattan corncob composite materials were developed and their mechanical properties were determined. This was with a view to producing alternative composite materials for automobile applications. Dried corncobs and rattan cane were crushed, treated with caustic alkali NaOH and transferred into a water bath machine to reduce the hydrophilic nature of the fibres in the polymer. The shredded corncobs and rattans cane were sun-dried after the treatment to remove the moisture content and were further pulverized and sieved to obtain 400μm particle size. Compositions of the particles were varied for seven samples with the binder kept constant at 80wt% of the whole mixture and forming them into particle panels using a metal mould. The process was repeated in order to obtain three replicates to get the exact mean value. The produced panels were tested for density, water absorption, tensile strength and modulus, flexural strength and modulus, and optical microstructure. The results revealed that the densities ranged between 1.06g/cm to 1.30g/cm , the water absorption properties ranged between 0.87% to 4.55%, tensile strength ranged between 42MPa to 90MPa, tensile modulus ranged between 2.2GPa to 5.9GPa, flexural strength ranged between 50MPa to 70MPa and flexural modulus ranged between 1.5GPa to 2.7GPa. It was concluded that the developed composite materials have good mechanical properties and could serve as alternative materials for making automobile accessories like bumpers and spoilers. It could also help in solving the problem of environmental pollution caused by open burning.

In this paper, the electronic, mechanical and thermodynamic properties of AlNi2Ti are studied by first-principles calculations in order to reveal the influence of AlNi2Ti as an interfacial phase on ZTA (zirconia toughened alumina)/Fe. The results show that AlNi2Ti has relatively high mechanical properties, which will benefit the impact or wear resistance of the ZTA/Fe composite. The values of bulk, shear and Young’s modulus are 164.2, 63.2 and 168.1 GPa respectively, and the hardness of AlNi2Ti (4.4 GPa) is comparable to common ferrous materials. The intrinsic ductile nature and strong metallic bonding character of AlNi2Ti are confirmed by B/G and Poisson’s ratio. AlNi2Ti shows isotropy bulk modulus and anisotropic elasticity in different crystallographic directions. At room temperature, the linear thermal expansion coefficient (LTEC) of AlNi2Ti estimated by quasi-harmonic approximation (QHA) based on Debye model is 10.6 × 10−6 K−1, close to LTECs of zirconia toughened alumina and iron. Therefore, the thermal matching of ZTA/Fe composite with AlNi2Ti interfacial phase can be improved. Other thermodynamic properties including Debye temperature, sound velocity, thermal conductivity and heat capacity, as well as electronic properties, are also calculated.

Promoting the feasibility of carbon films as electrode applications requires sufficient performances in view of both electrical and mechanical properties. Herein, carbon films with ultrahigh electrical conductivity and mechanical modulus are prepared by high temperature carbonization of polyacrylonitrile (PAN)/single‐walled carbon nanotube (SWNT) nanocomposites. Achieving both performances is ascribed to remarkable graphitic crystallinity, resulting from the sequential templating–coalescing behavior of concentrated SWNT bundles (B‐CNTs). While well‐dispersed SWNTs (WD‐CNTs) facilitate radial templating according to their tubular geometry, flattened B‐CNTs sandwiched between carbonized PAN matrices induce vertical templating, where the former and latter produce concentric and planar crystallizations of the graphitic structure, respectively. After carbonization at 2500 °C with the remaining WD‐CNTs as microstructural defects, the flattened B‐CNTs coalesce into graphitic crystals by zipping the surrounding matrix, resulting in high crystallinity with the crystal thicknesses of 27.4 and 39.4 nm for the (002) and (10) planes, respectively. For comparison, the graphene oxide (GO) containing carbon films produce a less‐ordered graphitic phase owing to irregular templating, despite the geometrical consistency. Consequently, PAN/B‐CNT carbon films exhibit exceptional electrical conductivity (40.7 × 104 S m−1) and mechanical modulus (38.2 ± 6.4 GPa). Thus, controlling the templating−coalescing behavior of SWNTs is the key for improving final performances of carbon films. Carbon films with exceptional electrical conductivity and mechanical modulus are prepared using polyacrylonitrile/single‐walled carbon nanotube (SWNT) nanocomposites through carbonization (2500 °C). High graphitic crystallinity is ascribed to the sequential templating−coalescing behavior of SWNT bundles. Contrary to the well‐dispersed SWNTs, the flattened SWNT bundles induce vertical templating and planar graphitic crystallization. Further, few SWNT bundles remain as defects owing to coalescence.

Thermal and mechanical properties of poly(ionic liquid)s (PILs), an epoxidized ionic liquid-amine network, are studied via molecular dynamics simulations. The poly(ionic liquid)s are designed with two different ionic liquid monomers, 3-[2-(Oxiran-2-yl)ethyl]-1-4-[(2-oxiran-2-yl)ethoxy]phenylimidazolium (EIM2) and 1-4-[2-(Oxiran-2-yl)ethyl]phenyl-3-4-[2-(oxiran-2-yl)ethoxy]benzylimidazolium (EIM1), each of which is networked with tris(2-aminoethyl)amine, paired with different anions, bis(trifluoromethanesulfonyl)imide (TFSI−) and chloride (Cl−). We investigate how ionic liquid monomers with high ionic strength affect structures of the cross-linked polymer networks and their thermomechanical properties such as glass transition temperature (Tg) and elastic moduli, varying the degree of cross-linking. Strong electrostatic interactions between the cationic polymer backbone and anions build up their strong structures of which the strength depends on their molecular structures and anion size. As the anion size decreases from TFSI− to Cl−, both Tg and elastic moduli of the PIL increase due to stronger electrostatic interactions present between their ionic moieties, making it favorable for the PIL to organize with stronger bindings. Compared to the EIM2 monomer, the EIM1 monomers and TFSI− ions generate a PIL with higher Tg and elastic moduli. This attributes to the less flexible structure of the EIM1 monomer for the chain rotation, in which steric hindrance by ring moieties in the EIM1-based PIL enhances their structural rigidity. The π-π stacking structures between the rings are found to increase in EIM1-based PIL compared to the EIM2-based one, which becomes stronger with smaller Cl− ion rather than TFSI−. The effect of the degree of the cross-linking on thermal and mechanical properties is also examined. As the degree of cross-linking decreases from 100% to 60%, Tg also decreases by a factor of 10–20%, where the difference among the given PILs becomes decreased with a lower degree of cross-linking. Both the Young’s (E) and shear (G) moduli of all the PILs decrease with degree of cross-linking, which the reduction is more significant for the PIL generated with EIM2 monomers. Transport properties of anions in PILs are also studied. Anions are almost immobilized globally with very small structural fluctuations, in which Cl− presents lower diffusivity by a factor of ~2 compared to TFSI− due to their stronger binding to the cationic polymer backbone.

The topographical distributions of the zonal properties of articular cartilage over the medial tibia from an experimental osteoarthritis (OA) model were evaluated as a function of external loading by microscopic Magnetic Resonance Imaging (µMRI). T2 relaxation times and cartilage thicknesses were measured at 17.6µm resolution from 118 specimens, which came from thirteen dogs (six 8-week and seven 12-week after surgery), with and without mechanical loading. In addition, bulk mechanical modulus was measured topographically from each tibia surface. The total thickness decreased significantly under the external loading, in which the relative thickness of the superficial zone (SZ) and the transitional zone (TZ) increased whereas the radial zones (RZs) decreased. In the bulk data, T2(55°) decreased significantly (p<0.001) at all OA-time-points, but T2(0°) decreased without significance (p>0.05) at 8-week. Complex relationships were found in the zonal tissue properties as a function of external loading with the progress of OA. T2 in the superficial zone changed more profoundly than the same properties in the radial zone as a function of external loading at all OA time-points. This study confirms that OA affects the load-induced changes in the molecular distribution and structure of cartilage, which are both depth-dependent and topographically distributed. Such detailed knowledge of mechanobiological changes in specific tibial cartilage zones and locations with OA progress could improve the early detection of the subtle softening of cartilage that accompanies pre-clinical stages of OA.

Limestone calcined clay cement (LC3) and recycled aggregates (RAs) are important innovations in civil engineering, offering solutions to the industry’s energy and carbon challenges. However, limited research on their combined use has hindered widespread application. This study systematically evaluates LC3-based concrete with both coarse and fine RAs, using material testing, cost analysis and carbon footprint assessments to examine the effects of water-to-binder ratio, metakaolin-limestone powder synergy, RA content and particle quality on workability, compressive strength, elastic modulus, splitting-tensile strength, unit cost and environmental impact, while establishing clear quantitative relationships. Key findings include: (i) Using up to 50% metakaolin-limestone powder by mass, 30% coarse RA and 20% recycled sand by volume results in minimal reductions in 28-day strength and elastic modulus. However, exceeding 70%, 50% and 40%, respectively, leads to significant mechanical deterioration. (ii) LC3 concrete has 4-15% lower strength than Portland cement concrete at 14 days due to slower pozzolanic reactions, but strength levels equalize by 28 days. Similarly, recycled aggregate concrete shows lower early-age strength, with extended curing further highlighting performance differences, likely due to the residual mortar on recycled particles. (iii) Lifecycle analysis confirms that replacing 50% of the binder with metakaolin-limestone powder reduces carbon emissions by 29.9% and costs by 12.4% for strength-equivalent concrete. In contrast, RAs offer only modest sustainability benefits, with 20% recycled sand and 30% coarse RA increasing emissions by 5.4% and 2.8%, respectively, while keeping costs stable. (iv) The quality of RA particles plays a key role in their sustainable application. Additionally, transportation distance significantly affects the circular benefits of RA use but has a limited impact on the sustainability of metakaolin-limestone powder.

It remains poorly understood if carrier hardness, elastic modulus, and contact area affect neural stem cell growth and differentiation. Tensile tests show that the elastic moduli of Tiansu and SMI silicone membranes are lower than that of an ordinary dish, while the elastic modulus of SMI silicone membrane is lower than that of Tiansu silicone membrane. Neural stem cells from the cerebral cortex of embryonic day 16 Sprague-Dawley rats were seeded onto ordinary dishes as well as Tiansu silicone membrane and SMI silicone membrane. Light microscopy showed that neural stem cells on all three carriers show improved adherence. After 7 days of differentiation, neuron specific enolase, glial fibrillary acidic protein, and myelin basic protein expression was detected by immunofluorescence. Moreover, flow cytometry revealed a higher rate of neural stem cell differentiation into astrocytes on Tiansu and SMI silicone membranes than on the ordinary dish, which was also higher on the SMI than the Tiansu silicone membrane. These findings con- firm that all three cell carrier types have good biocompatibility, while SMI and Tiansu silicone membranes exhibit good mechanical homogenization. Thus, elastic modulus affects neural stem cell differentiation into various nerve cells. Within a certain range, a smaller elastic modulus re- sults in a more obvious trend of cell differentiation into astrocytes.

This study examined the hypothesis that meniscal allograft transplantation serves a “chondroprotective” role and prevents the histological and biomechanical changes of the articular cartilage following meniscectomy. Skeletally mature mongrel dogs underwent total medial meniscectomy and received either a fresh meniscal allograft (n=10) or no further treatment (n=10). Semiquantitative histology and biomechanical analysis of the femoral articular cartilage was used to assess cartilage pathology 12 weeks following surgery. Histological analysis showed significant changes in cartilage structure that did not differ between the meniscectomy and allograft transplantation groups. Similarly, the tensile modulus of the surface zone cartilage was significantly lower than that in unoperated controls following either meniscectomy or allograft transplantation. A significant correlation was observed between the biomechanical and histological changes, suggesting that degenerative changes in cartilage structure and mechanical function are interrelated. Our findings do not support the hypothesis that meniscal allograft transplantation provides chondroprotection of the femoral condyle and also suggest that it does not lead to increased degenerative changes.