Hydrogels with high mechanical strength and injectability have attracted extensive attention in biomedical and tissue engineering. However, endowing a hydrogel with both properties is challenging ...because they are generally inversely related. In this work, by constructing a multi‐hydrogen‐bonding system, a high‐strength and injectable supramolecular hydrogel is successfully fabricated. It is constructed by the self‐assembly of a monomeric nucleoside molecular gelator (2‐amino‐2′‐fluoro‐2′‐deoxyadenosine (2‐FA)) with distilled water/phosphate buffered saline as solvent. Its storage modulus reaches 1 MPa at a concentration of 5.0 wt%, which is the strongest supramolecular hydrogel comprising an ultralow‐molecular‐weight (MW < 300) gelator. Furthermore, it exhibits excellent shear‐thinning injectability, and completes the sol–gel transition in seconds after injection at 37 °C. The multi‐hydrogen‐bonding system is essentially based on the synergistic interactions between the double NH2 groups, water molecules, and 2′‐F atoms. Furthermore, the 2‐FA hydrogel exhibits excellent biocompatibility and antibacterial activity. When applied to rat molar extraction sockets, compared to natural healing and the commercial hemorrhage agent gelatin sponge, the 2‐FA hydrogel exhibits faster degradation and induces less osteoclastic activity and inflammatory infiltration, resulting in more complete bone healing. In summary, this study provides ideas for proposing a multifunctional, high‐strength, and injectable supramolecular hydrogel for various biomedical engineering applications.
Simultaneously achieving high strength and injectability in one hydrogel is challenging. A high strength and injectable supramolecular hydrogel is constructed by the self‐assembly of a monomeric nucleoside molecular gelator (2‐amino‐2′‐fluoro‐2′‐deoxyadenosine (2‐FA)). Notably, it exhibits excellent biocompatibility, fast biodegradation, antibacterial property, and osteoclast inhibition, making it a potential candidate biomaterial for tooth‐extraction wound healing and tissue engineering.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Kraft lignin particles (KLPs) were introduced into a commercial biodegradable poly(butylene adipate-co-terephthalate) (PBAT) matrix to produce composite material in a mini-extruder. The effect of ...KLPs content on the morphology, thermal, crystalline, and micro and macro mechanical properties of the PBAT/KLPs was investigated. Results showed that the tensile properties of PBAT improved with the addition of lignin. Dynamic Mechanical Analysis (DMA) showed that the storage modulus of composites increased with increasing of KLPs and Tg slightly shifted to a lower temperature. Differential scanning calorimetry (DSC) revealed that lignin strongly nucleates the crystallization of PBAT. Thermogravimetric analysis (TGA) showed that composites started to degrade at a lower temperature compared with neat PBAT while displaying higher ash residue. Small-angle X-ray scattering (SAXS) analysis showed that under a uniaxial stretch of the PBAT/KLP films nano and microcavities formed due to the debonding of PBAT from KLPs in their polar regions.
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•Green composite from kraft lignin and PBAT were prepared successfully.•The incorporation of lignin as filler lead to enhance the rigidity of PBAT.•Lignin particles accelerate crystallization of PBAT.•The storage modulus of composites increased at temperatures below the Tg.•PBAT is free from inherent cavitation even at a high draw ratio.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The study analyzed the dynamics mechanical properties of carbon fiber‐reinforced polyetheretherketone (CF/PEEK) under multi‐consecutive temperature scans and establish an evaluation model of storage ...modulus to facilitate application in high/low temperature. The dynamic mechanical properties of CF/PEEK laminate sheets obtained via hot‐pressing procedure were subjected to a dynamic mechanical cycle test. The micromorphology and microstructure were observed with a scanning electron microscopy. The structural evolution of CF/PEEK and the interface between carbon fiber and PEEK matrix were analyzed. The characteristic variation of storage modulus, loss modulus, and loss factor are discussed and the damping properties are studied in different temperature ranges. The results show that the dynamic mechanical properties of CF/PEEK were become stabilized after the first temperature scan, while the glass transition temperature remained basically unchanged. The storage modulus of the material increased by 15.8% and the peak value of the loss factor curve increased by 14.4%. Based on the experimental data, an evaluation model of the storage modulus was formulated and validated by the test results obtained to provide an accurately predicting the dynamic mechanical properties of CF/PEEK and expand its engineering applications.
After the first temperature scan, a certain amount of polyetheretherketone (PEEK) is embedded and attached in the grooves among the fibers, and the distribution of PEEK in the fiber is more uniform. The contact area and bonding strength between the fiber and the matrix increases, and the interface performance is effectively improved, resulting in enhanced dynamic mechanical properties of carbon fiber‐reinforced polyetheretherketone (CF/PEEK). For this reason, the characteristic variation of storage modulus, loss modulus, and loss factor are discussed, and the fitted storage modulus model can accurately reflect the storage variation of CF/PEEK.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Relationships between the size of particles and the water holding capacity or storage modulus of chemical-induced soy protein gels were investigated in the present study. Heat-induced protein ...aggregates with different sizes ranging from 92.7 to 525.2 nm were obtained by heating the protein mixtures of varying β-conglycinin/glycinin (7S/11S) ratios at 100 °C for 30 min, then they were cross-linked by glutaraldehyde to form the gels. Larger aggregates were formed at lower 7S/11S ratio, and the ratio of the aggregates in protein suspensions increased from 35.7% to 65.6% when the 7S/11S ratio decreased from 5:0 to 0:5. Reducing SDS-PAGE showed that basic polypeptides of 11S played an important role in the forming of larger particles. Scanning electron microscope results revealed that coarser gel networks with larger pores were formed when larger aggregates were participated in forming a gel. The water loss rate increased from 8.2% to 33.3% as the 7S/11S ratio decreased from 5:0 to 0:5, and a positive correlation between the size of particles and the water loss rate of gel network was found, which could be attributed to coarser gel structure formed by larger aggregates. However, a negative relationship between the size of protein aggregates and the storage modulus of gels was observed, due to that more cross links were induced by glutaraldehyde when smaller protein particles were present in gel network.
•Larger aggregates were mainly composed of basic polypeptides.•Chemical-induced gels by larger particles were of higher water loss rates.•Higher G′ values were found in gels with smaller aggregates.•A negative correlation between water loss rate and G′ values of gels was found.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The underlying cause of mechanical anisotropy in additively manufactured (AM) parts is not yet fully understood and has been attributed to several different factors like microstructural defects, ...residual stresses, melt pool boundaries, crystallographic and morphological textures. To better understand the main contributing factor to the mechanical anisotropy of AM stainless steel 316L, bulk specimens were fabricated via laser powder bed fusion (LPBF). Tensile specimens were machined from these AM bulk materials for three different inclinations: 0°, 45°, and 90° relative to the build plate. Dynamic Young’s modulus measurements and tensile tests were used to determine the mechanical anisotropy. Some tensile specimens were also subjected to residual stress measurement via neutron diffraction, porosity determination with X-ray micro-computed tomography (μCT), and texture analysis with electron backscatter diffraction (EBSD). These investigations revealed that the specimens exhibited near full density and the detected defects were spherical. Furthermore, the residual stresses in the loading direction were between −74±24MPa and 137±20MPa, and the EBSD measurements showed a preferential 〈110〉 orientation parallel to the build direction. A crystal plasticity model was used to analyze the elastic anisotropy and the anisotropic yield behavior of the AM specimens, and it was able to capture and predict the experimental behavior accurately. Overall, it was shown that the mechanical anisotropy of the tested specimens was mainly influenced by the crystallographic texture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The fast loss of fluidity of sodium silicate-activated slag (SS-AAS) systems have been widely studied in the literature. In this study, the rheology of these cements has been correlated with the ...evolution of the reaction products formed over time. For this purpose, a combination of experimental characterization techniques, to study the pore solution composition and microstructure of SS-AAS pastes and thermodynamic calculations have been applied.
The initial precipitation of ill-defined N-A-S-H and C-N-A-S-H producta leads to a fast increase of the storage modulus after 40 min of reaction. These products are formed from the reaction of the Na+ ions and silicate ions of the activator with the Ca2+ and aluminate species dissolved from the slag. However, when a shear is applied, the structure breaks down and fluidity is recovered, that infers that the attractive forces between the particles are low at the early stages of hydration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The structural build-up of cementitious paste with nano-Fe3O4 under time-varying magnetic fields was experimentally investigated using small amplitude oscillatory shear (SAOS) technique. Several ...modes of magnetic fields, such as constant, sudden-changed and linearly-changed, were applied to the cementitious paste. Results showed that the structural build-up of the cementitious paste depended on the magnetizing time and magnetic field strength. Applying constant magnetic fields improved the liquid-like behavior during first minutes and afterwards the solid-like property was enhanced. Both the sudden-increased and sudden-decreased magnetic fields resulted in a sharp decrease in storage modulus. The linearly increasing magnetic field resulted in a slight increase in storage modulus but higher liquid-like behavior. When the magnetic field was linearly decreased from 0.5 T to approx. 0.25 T, the structural build-up was enhanced significantly, and with the continuously decreasing magnetic field from approx. 0.25 T to 0 T, a decrease in storage modulus was observed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Nanocomposites of epoxy with 3 and 5 wt% graphene nanoplatelets (GnPs) were fabricated with GnP sizes of ~5 and <1 μm dispersed within an epoxy resin using a sonication process followed by three-roll ...milling. The morphology, mechanical, and thermal properties of the composites were investigated. Tensile and flexural properties measurements of these nanocomposites indicated higher modulus and strength with increasing concentration of small GnPs sizes (<1 μm, GnP-C750). The incorporation of larger GnPs sizes (~5 μm, GnP-5) significantly improved the tensile and flexural modulus but reduced the strength of the resulting composites. At 35 °C, the dynamic storage modulus of GnP-5/epoxy composites increased with increasing platelet concentration, and improved by 12 % at 3 wt% and 23 % at 5 wt%. The smaller GnP-C750 increased the storage modulus by 5 % at 3 wt% loading but only 2 % at 5 wt% loading. The glass transition temperatures of the composites increased with increasing platelet concentration regardless of the GnP particle size. A marked improvement in thermal conductivity was measured with the incorporation of the larger GnP size reaching 115 % at 5 wt% loading. The effects of different platelet sizes of the GnP reinforcement on the damage mechanisms of these nanocomposites were studied by scanning electron microscopy.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Thermosetting polymers have been demonstrated to exhibit improved mechanical properties when nanofillers are introduced. These improvements can be further increased through the introduction of ...covalent linkages between the polymer matrix and nanofillers that enhances the chemical interaction. Here, aramid nanofibers (ANFs) are functionalized using a glycidyl ether silane coupling agent and their effect on the mechanical properties of epoxy are investigated. The results show that Young's modulus and tensile strength of 1 wt % epoxy functionalized ANFs (EANFs) reinforced nanocomposites increase by 16.8% and 14.0%, respectively, and fracture toughness increases by 4.4 times with the addition of 1.5 wt % EANFs. Additionally, both an increase in storage modulus and glass transition temperature are observed during dynamic mechanical analysis with increasing percentage of EANFs. Thus, this work demonstrates that the EANFs can further enhance the mechanical properties of epoxy nanocomposites through chemical crosslinking between the epoxy matrix and ANFs.
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•Aramid nanofibers (ANFs) are functionalized using a glycidyl ether silane coupling agent.•The effect of epoxy functionalized ANFs (EANFs) on the properties of epoxy nanocomposites is investigated.•The mechanical and viscoelastic properties of EANF reinforced epoxy nanocomposites are improved.•The chemical crosslinking between the polymer and ANFs further enhances the mechanical properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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