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A series of micro hollow glass beads (HGB) filled castor oil-based polyurethane/epoxy resin graft interpenetrating polymer network (IPN) composites were prepared. The tensile and impact strengths, impact fractured surfaces, damping properties and thermal stability of the IPN composites were studied systematically in terms of composition. Results revealed that the addition of HGB into polyurethane/epoxy IPN can significantly improve not only the tensile strength but also the impact strength. The tensile strength was increased by 61% and at the same time the impact strength was increased by 25% when the HGB content was 1.5%. The damping properties were better than the composition of 0.5% or 2% HGB content when the HGB content was 1% or 1.5%. The thermal decomposition temperature was also slightly improved by the incorporation of HGB. It is suggested that the HGB reinforced polyurethane/epoxy resin IPN composites could be used as structural damping materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A biomimetic strategy to prepare supramolecular polyurethanes (SPUs) was described. • The polymer networks were significantly enhanced by H-bonds and coordination bonds. • SPUs showed ultrahigh modulus (146.92 MPa) and excellent self-healing (95%, 24 h). • A bilayer polymer film was designed to realize fast self-healing at room temperature. Developing a new generation of polymeric materials that integrate robust mechanical properties with ultra-high self-healing efficiency at ambient temperature remains a formidable challenge due to the proverbial trade-offs among strength, toughness, and self-healing ability. Herein, inspired by biological systems (titin protein molecular structure and Nereis jaws), a series of updated supramolecular polyurethanes have been successfully synthesized by incorporating hierarchical hydrogen-bonding motifs into the polymer matrix and subsequently coordinated with Zn2+ ions. Relying on collaborative reinforcement of optimized hierarchical hydrogen bonds and metal-ligand coordination bonds, the resulted supramolecular elastomers exhibited a robust strength of ∼14.15 MPa, an excellent toughness of ∼47.57 MJ m−3, and Young's modulus of ∼146.92 MPa. Benefiting from the rational design of hard domains, high mobility of chains, and the synergistic effect of multiple non-covalent interactions, the mechanical properties are far superior to the previously reported room‐temperature self‐healing materials. In addition, with the structural design of "inner soft and external hard" model, we also fabricated a bilayer polymer film with a gradient distribution that can achieve rapid self-healing, with an unexpectedly high self-healing efficiency of 95% at ambient temperature in 24 h. This work opens up a new avenue for fabricating room-temperature self-healing materials with robust mechanical strength and toughness at the same time. [ABSTRACT FROM AUTHOR]

Shield tunnel muck are usually discarded due to high water content and poor engineering properties, resulting in occupation of land sources and waste of soil sources. Meanwhile, large amounts of industrial waste such as carbide slag (CS) and soda residue (SR) are landfilled with a low reuse rate, which poses a threat to the natural environment. This study aims to improve waste shield tunnel muck using CS and SR and traditional lime, and the improved tunnel muck is expected to be used in subgrade filling to provide a new approach to solve this dilemma. A series of physical, mechanical, subgrade property, and microcosmic tests were conducted on shield tunnel muck improved by CS, SR and lime. The effects of different mixing proportions on the properties of improved tunnel muck were examined. The micro-improvement mechanisms of CS and SR on tunnel muck were explored. Results indicate that the addition of CS or SR can effectively improve the physical and mechanical properties of shield tunnel muck. CS plays a significantly role than SR in improving physical and mechanical properties of tunnel muck. A synergistic enhancement is observed as the combined CS and SR are added, and the optimal mixing proportion of tunnel muck to CS to SR is found to be 100:6:2 with a fixed lime content of 4 %. The alkaline environment created by the synergistic action of CS and SR promotes the dissolution of the active ions in soils, and the generated crystals and gelling products of hydration significant contribute to soil improvement. The tunnel muck improved with appropriate CS or SR content could meet the requirements for light or medium traffic load levels and can be effectively utilized as subgrade filling. • Carbide slag or soda residue enhances tunnel muck's properties significantly. • Mechanical properties plateau in tunnel muck beyond 6 % carbide slag content. • Combined carbide slag and soda residue has a synergistic enhancement. • Optimal mix: tunnel muck, carbide slag, soda residue (100:6:2) with fixed 4 % lime. • Carbide slag / soda residue - enhanced tunnel muck meets subgrade performance norms. [ABSTRACT FROM AUTHOR]

In recent years, TiO 2 nanotube has presented great potentials in blood-contacting implants. However, considering the reliability and safety of the application and complexity of coagulation mechanism, the physicochemical property and hemocompatibility of phase dependent TiO 2 still need to be investigated deeply. In this research, the wettability, electrochemical properties, mechanical properties, and whole blood coagulation response of phase dependent TiO 2 nanotubes were systematically evaluated. First, the surface topography and crystal phase of regular self-ordering TiO 2 nanotubes arrays were characterized, some significant changes including fracture, collapse and micropores appeared with the increase of annealed temperature, which mainly caused by transformation of crystal structure. Secondly, the physicochemical properties were analyzed, which presented that the superhydrophilicity, hardness, elastic modulus, adhesive strength of TiO 2 nanotubes gradually decrease with the increase of annealed temperature; the mean coefficient of friction increases when the crystal phase of TiO 2 nanotubes transferred from amorphous into anatase, whereas it decreases with the increase of rutile phase content; and the rutile phase displays excellent resistant element precipitation due to the increase of grain boundary density and close packed crystal structure. Finally, the whole blood was applied to evaluate the hemocompatibility of phase dependent TiO 2 nanotubes by in vitro experiment. The deteriorative surface morphology and lower interfacial tension of nanotubes array composed of rutile phase can effectively avoid adhesion and activation of platelets. This research can provide a useful guide to design the TiO 2 -nanotube-based blood compatible biomaterials. Unlabelled Image • The surface topography including fracture, collapse and micropores appear with the increase of annealed temperature, which are mainly caused by transformation of crystal structure. • The TiO 2 nanotube array presents a smallest friction coefficient at 450°C, the mean friction coefficient decreases with the increase of rutile phase content and deterioration of surface topography. • The hardness, elastic modulus and adhesive strength gradually decrease with the increase of annealed temperature. • In simulated human body fluid, the increase of grain boundary density and close packed crystal structure of rutile result in the enhancement of corrosion resistance. • The deteriorative surface morphology and lower interfacial tension of nanotubes array composed of rutile phase can effectively avoid adhesion and activation of platelets. [ABSTRACT FROM AUTHOR]

In this paper, the corresponding densification, microstructure, precipitate phase and mechanical properties of Al-14.1Mg-0.47Si-0.31Sc-0.17Zr fabricated by selective laser melting were detailly investigated. The experimental result shows that the densification of SLM specimens increased first and then decreased with energy density. Even at the same energy density, the relative densities of the samples are also different, and the printed sample has a high densification under the condition of low laser power and scanning speed. Two typical microstructures (fine grain zone and coarse grain zone) were formed inside the printed samples due to the formation of Al 3 (Sc, Zr) particles (coherent with the Al matrix) during the solidification process of SLM. As fabricated at 200 W and 500 mm/s, the average grain size of the SLM sample is 2.07 (Y-Z plane) and 1.72 μm (X–Y plane), and the maximum values of nano-hardness and tensile strength were 2.19 GPa and 510 MPa, respectively. The mechanical properties increased due to the combined effect of fine grain strengthening and dispersed distribution of precipitates in Al matrix. With a low density (2.537 g/cm3) and high tensile strength, the components fabricated by this alloy have more extensive spreading values and prospects for applying due to the excellent mechanical performance. [ABSTRACT FROM AUTHOR]

A novel Sc- and Zr- modified 7075 Al alloy with a low microalloying content (0.4 wt% Sc and 0.25 wt %Zr) was designed and the influence of process parameters on the microstructure and mechanical properties of selective laser melting (SLM) samples was systematically analyzed. As the SLM energy input increased, the relative density of block specimens first increased before plateauing. At a high energy density, crack defects disappeared, and the average grain size significantly decreased. For the specimen fabricated at 375 J/mm3, the average grain size was 2.6 μm, which is only 9.8% of the size of samples fabricated at 44 J/mm3. Due to fine grain strengthening, the mechanical properties of the printed specimens were remarkably improved, but the high energy input softened the matrix. Due to these two opposing effects, the compressive strength and nano-hardness of specimens fabricated at 375 J/mm3 were 621 MPa and 1.85 GPa, which are respectively 129.6% and 98.4% of the specimen fabricated at 44 J/mm3. [ABSTRACT FROM AUTHOR]