Search Results (287)

The emulsification of a molten fusible metal alloy in a liquid epoxy matrix with its subsequent curing is a novel way to create a highly concentrated phase-change material. However, numerous challenges have arisen. The high interfacial tension between the molten metal and epoxy resin and the difference in their viscosities hinder the stretching and breaking of metal droplets during stirring. Further, the high density of metal droplets and lack of suitable surfactants lead to their rapid coalescence and sedimentation in the non-cross-linked resin. Finally, the high differences in the thermal expansion coefficients of the metal alloy and cross-linked epoxy polymer may cause cracking of the resulting phase-change material. This work overcomes the above problems by using nanosilica-induced physical gelation to thicken the epoxy medium containing Wood’s metal, stabilize their interfacial boundary, and immobilize the molten metal droplets through the creation of a gel-like network with a yield stress. In turn, the yield stress and the subsequent low-temperature curing with diethylenetriamine prevent delamination and cracking, while the transformation of the epoxy resin as a physical gel into a cross-linked polymer gel ensures form stability. The stabilization mechanism is shown to combine Pickering-like interfacial anchoring of hydrophilic silica at the metal/epoxy boundary with bulk gelation of the epoxy phase, enabling high metal loadings. As a result, epoxy shape-stable phase-change materials containing up to 80 wt% of Wood’s metal were produced. Wood’s metal forms fine dispersed droplets in epoxy medium with an average size of 2–5 µm, which can store thermal energy with an efficiency of up to 120.8 J/cm³. Wood’s metal plasticizes the epoxy matrix and decreases its glass transition temperature because of interactions with the epoxy resin and its hardener. However, the reinforcing effect of the metal particles compensates for this adverse effect, increasing Young’s modulus of the cured phase-change system up to 825 MPa. These form-stable, high-energy-density composites are promising for thermal energy storage in building envelopes, radiation-protective shielding, or industrial heat management systems where leakage-free operation and mechanical integrity are critical. Full article

Background: Aloe vera gel in 0.3% hyaluronate (AV/HA) could mitigate glaucoma therapy-related ocular surface disease (GTOSD). Methods: Thirty-nine patients diagnosed with GTOSD and receiving AV/HA or HA underwent ocular surface disease index (OSDI), Symptom Assessment iN Dry Eye (SANDE), National Eye Institute Visual Function Questionnaire (NEI VFQ)-25 questionnaires, and tear matrix metalloproteinase-9 (MMP-9), break-up time (BUT), corneal fluorescein staining (CFS), Schirmer test I (STI), and bulbar conjunctival hyperemia (BCH) determination. Results: After one month, AV/HA increased BUT (5 (7–4.5) to 7 (8–5.5)) and STI (12 (19.5–8) to 13.5 (20–10)), while it decreased BCH (2.2 (2.3–1.3) to 2.1 (2.2–1.2)) and CFS (3 (4–2) to 2 (3.0–1.5)) (p < 0.001). SANDE and OSDI scores were reduced from 36.18 (38.5–20.5) to 22.91 (31.5–17.21), and 29.5 (32.5–19.5) to 20 (26.5–18) (p < 0.001). HA reduced BCH from 2.75 (3.20–2.15) to 2.25 (2.30–1.90) (p = 0.014) and CFS from 3.5 (5–2.75) to 2.5 (4–2) (p = 0.014), while it increased BUT (p = 0.036). The SANDE score decreased from 28.95 (47.6–20.9) to 26.86 (36.41–19.90) (p = 0.009), whereas the OSDI decreased from 40 (49–19.5) to 29 (42–19.75) (p = 0.005). Any significant change in NEI VFQ-25 was collected. A trend for an MMP-9 immunoassay positivity reduction was observed in AV/HA (0.073). Conclusions: These findings invite considering lubricants enriched with natural anti-inflammatory agents, such as Aloe vera, as a potential adjunctive option to improve the ocular surface in glaucoma. Full article

To address the issues of slow curing rate, post-curing reactions, and suboptimal mechanical properties in the carboxyl-terminated polybutadiene (CTPB)/epoxy resin (EP) binder system used for solid propellants, this study optimized the curing system by introducing 593 aliphatic amine compounds containing primary and secondary amine groups as a cure accelerator. It is found that the incorporation of the cure accelerator improved the fracture strength and elongation at break of the CTPB/EP binder system. With the addition of 0.3 wt.% cure accelerator, the tensile fracture strength increased to 0.37 MPa, while the elongation at break reached 655%. Moreover, augmenting the quantity of cure accelerator can substantially elevate the crosslink density and gel fraction of the binder system. When the addition reaches 0.3 wt.%, the crosslink density is 4.3 × 10⁻⁴ mol/cm³. Further studies showed that 593 cure accelerator reduced the activation energy of the curing reaction of the CTPB/EP binder system, with higher levels of cure accelerator resulting in lower activation energy. This study established a preparation methodology for a CTPB/EP binder system with high elongation and tensile strength. These findings provide a solid scientific foundation for the application of CTPB-based binder systems in solid propellants. Full article

The coal washing and processing industry generates substantial quantities of coal gangue, which exerts significant impacts on soil and groundwater environments. Activating the reactivity of inert coal gangue to achieve comprehensive utilization in the field of cementitious materials holds considerable importance. This study investigates a method that synergistically utilizes thermal activation and mechanical activation to enhance the reactivity of coal gangue. The approach aims to reduce the temperature required for thermal activation while effectively stimulating the reactive properties. Furthermore, the mechanisms underlying the thermal–mechanical synergistic activation and its hydration characteristics are thoroughly examined. Experimental results demonstrate that thermo-mechanical synergistic activation, in comparison to sole thermal activation at 950 °C, enhances reaction activity by 28.3%, improves mechanical properties by 27.4%, reduces setting time by 65 min, and significantly optimizes flow performance. The XRD, FT-IR, and TG-DTG analyses demonstrate that the interlayer hydrogen bonds of kaolinite are disrupted during the thermal activation stage, resulting in the formation of amorphous and highly reactive metakaolinite. Subsequent mechanical activation after thermal treatment significantly reduces particle size, further breaks the interlayer hydrogen bonds of kaolinite, and leads to the complete disintegration of the lattice framework. This process markedly enhances the degree of amorphization and thoroughly disrupts the long-range ordered crystalline structure of the kaolinite mineral phase in coal gangue. Concurrently, the d002 interplanar spacing of kaolinite expands by 0.155 Å, leading to an increase in reactivity. SEM-EDS analysis reveals that C-S-H gel is embedded within the mortar matrix, with a reduction in calcium hydroxide content and Ca/Si ratio, and an increase in Al/Si ratio in coal gangue mortar. This confirms that the thermo-mechanical synergistic activation introduces highly reactive Ca²⁺ and Al³⁺ from coal gangue into the secondary hydration reaction, resulting in the formation of a gel structure characterized by high stability and enhanced durability. Full article

In order to address the challenges of soft coal texture, poor permeability, and wellbore instability in tectonic coal reservoirs, a new biodegradable fuzzy-ball drilling fluid combined with a bio-based surfactant and enzyme system was developed. The optimal formula was determined through single-factor experiments and orthogonal optimization: 6% KCl–2% trehalose composite base slurry + 4% carboxymethyl chitosan + 0.4% hydroxypropyl methylcellulose + 0.15% xanthan gum + 0.12% guar gum + 0.3% cocamidopropyl betaine + 0.15% lauryl alcohol + 0.2% triethanolamine, with the degrading agent consisting of 0.2% composite-modified amylase + 0.04% composite-modified cellulase. The performance evaluation results show that the drilling fluid has stable rheological properties in the temperature range of 40~60 °C (yield point-plastic viscosity ratio: 0.8~0.9) and low filtration loss (5.8~6.5 mL); it exhibits excellent inhibition on tectonic coal, the inhibition rate of linear expansion rate is 72.1%, and the 14-mesh rolling recovery rate is 82.5%; at 55 °C, the gel breaking rate reaches 96.9% after 1.5 h, the mud cake removal rate reaches 98.8%, and the permeability recovery rate reaches 84.8%. After applying this drilling fluid, the unconfined compressive strength of tectonic coal increases from 1.2 MPa to 2.8 MPa (an increase of 133.3%), and the triaxial compressive strength increases from 20.1 MPa to 38.5 MPa (an increase of 91.5%); the numerical simulation shows that the radial displacement around the wellbore decreases by 62.1% and the plastic zone area shrinks by 73.2%. This novel biodegradable fuzzy-ball drilling fluid has the characteristics of efficient wellbore stabilization, easy degradation, and low formation damage, providing effective technical support for the green development of coalbed methane in tectonic coal reservoirs. Full article

This study addresses the challenges of low-pressure oil well workover operations, namely, severe loss of water-based workover fluid, significant reservoir damage from conventional temporary plugging agents, and slow production recovery, by focusing on the yet-mechanistically unclear “fuzzy-ball workover fluid.” Laboratory experiments combined with field data were used to evaluate its plugging performance and reservoir-protective mechanisms. In sand-filled tubes (diameter 25 mm, length 20–100 cm) sealed with the fuzzy-ball fluid, the formation’s bearing capacity increased by 3.25–18.59 MPa, showing a positive correlation with the plugging radius. Compatibility tests demonstrated that mixtures of crude oil and workover fluid (1:1) or crude oil, workover fluid, and water (1:1:1) held at 60 °C for 80 h exhibited only minor apparent viscosity reductions of 4 mPa·s and 2 mPa·s, respectively, indicating good stability. After successful plugging, a 1% ammonium persulfate solution was injected for 2 h to break the gel; permeability recovery rates reached 112–127%, confirming low reservoir damage and effective gel-break de-blocking. Field data from five wells (formation pressure coefficients 0.49–0.64) showed per-well fluid consumption of 33–83 m³ and post-workover liquid production index recoveries of 5.90–53.30%. Multivariate regression established mathematical relationships among bearing capacity, production index recovery, and fourteen geological engineering parameters, identifying the plugging radius as a key factor. Larger radii enhance both temporary plugging strength and production recovery without harming the reservoir, and they promote production by expanding the cleaning zone. In summary, the fuzzy-ball workover fluid achieves an integrated “high-efficiency plugging–low-damage gel-break–synergistic cleaning” mechanism, resolving the trade-off between temporary-plugging strength and production recovery in low-pressure wells and offering an innovative, environmentally friendly solution for the sustainable and efficient exploitation of oil–gas resources. Full article

This work investigates the modification of poly(lactic acid) (PLA) film properties for food packaging applications through the incorporation of modified gelatin (Gel-mod) and a choline chloride/glycerol deep eutectic solvent (DES). PLA/Gel-mod/DES materials were melt-processed and evaluated with respect to structure, morphology, thermal and mechanical behavior, processability, wettability, barrier performance, and compostability. Two incorporation routes were investigated for adding Gel-mod into the PLA matrix: direct incorporation and masterbatch preparation. FTIR and SEM analyses confirmed improved interfacial interactions and more homogeneous dispersion when Gel-mod was directly incorporated, compared with the masterbatch route. DES acted as an effective plasticizer and nucleating agent, reducing Tg, increasing crystallinity, and enhancing processability while maintaining thermal stability. Mechanical properties decreased relative to neat PLA, primarily due to increased crystallinity and chain scission. PLA_4Gel-mod demonstrated a more balanced performance, with higher elongation at break and improved processability than the other formulations, likely due to its single processing cycle, which minimized PLA degradation. Increased hydrophilicity led to higher water vapor transmission rates, correlating with accelerated biodegradation. Overall, the synergistic incorporation of DES and gelatin provides a viable strategy to tailor PLA properties, enabling the development of compostable packaging films suitable for sustainable food contact applications. Full article

Shale reservoirs contain abundant organic matter, pyrite, and clay minerals, making them highly susceptible to fluid-sensitivity damage; consequently, conventional hydraulic fracturing often yields poor stimulation performance, with low fracturing fluid flowback and rapid post-treatment production decline. Oxidative dissolution, however, can significantly alter the physical properties of shale reservoirs and improve stimulation effectiveness. In this study, nuclear magnetic resonance (NMR), contact-angle measurements, and triaxial compression tests are combined to systematically evaluate the effects of oxidative dissolution on the pore structure, wettability, and mechanical properties of Wufeng Formation shale from the Sichuan Basin. Core-flooding experiments with NaClO solutions show that, as the oxidant dosage (pore volume) increases, shale permeability rises by 66.67–266.67% and porosity by 1.79–9.58%, while the hydrophilic surface fraction increases from 5.45% to 61.73%. These changes are accompanied by a steady reduction in rock strength: the compressive strength decreases by up to 57.8%, and the elastic modulus exhibits a non-monotonic response to oxidation. Oxidative dissolution preferentially enlarges micropores, improves pore connectivity, and strengthens water wetness by consuming oil-wet organic matter and pyrite, which also enhances gel-breaking efficiency. Based on the experimental results, a series of characterization models are developed for oxidized shale reservoirs, including quantitative relationships linking porosity to compressive strength, elastic modulus, and contact angle, as well as a model relating oxidant dosage to microscopic pore structure evolution and imbibition enhancement. Overall, the coupled modifications of pore structure, wettability, and mechanical behavior produced by oxidative dissolution synergistically broaden the effective action range of fracturing fluids, promote shale gas desorption, and improve hydrocarbon seepage, providing a theoretical basis and practical guidance for oxidation-assisted stimulation in shale reservoirs. Full article

Addressing the issues of low permeability, stress sensitivity in CBM reservoirs, and severe reservoir damage from traditional fracturing fluids, we prepared a Gemini surfactant (designated GEM-CBM) for CBM development using ethanolamine, epichlorohydrin, and alkylamidopropyl dimethylamine as feedstocks. On this basis, we further developed a clean fracturing fluid system. The synthesis process of GEM-CBM was optimized via single-factor and orthogonal experiments. The surface activity of GEM-CBM was assessed through surface tension measurements, whereas the sand-carrying capacity, the rheological properties, gel-breaking performance, and reservoir compatibility were comprehensively examined. The optimal conditions for GEM-CBM are listed as follows: the molar ratio of intermediate to alkylamidopropyl dimethylamine being 1:2.2, reacted at 80 °C for 20 h, with a conversion rate of 96.5%. FTIR verified the existence of characteristic functional groups, and EA results matched the theoretical molecular composition. GEM-CBM has good performance, with a critical micelle concentration (CMC) of 19.0 μmol/L and a surface tension at CMC (γCMC) of 37.44 mN/m. The optimized clean fracturing fluid (formulation: 2.3% GEM-CBM + 0.3% Tween-80 + simulated formation water with 150,000 mg/L mineralization) exhibited a viscosity of 82 mPa·s (66.7% viscosity retention rate) after being subjected to 100 min of shearing at 90 °C and 170 s⁻¹. At 90 °C, the proppant settlement velocity was less than 0.15 mm/s, and complete gel breaking was achieved within 30 min without residues. For coal cores from the Qinshui Basin, the permeability recovery rate reached 78.6%. The permeability recovery rate of coal cores from the Qinshui Basin reached 78.6%. This fracturing fluid realizes viscosity enhancement and sand carrying via the worm-like micellar network formed by GEM-CBM, inducing minimal damage to CBM reservoirs and offering technical support for efficient CBM extraction. Full article

This study systematically investigates the mechanical behavior and failure mechanisms of cemented tailings backfill (CTB) prepared from classified and unclassified tailings across cement-to-tailings (C/T) ratios of 1:8, 1:6, and 1:4 and slurry concentrations of 60%, 65%, and 70%. Specimens were evaluated by uniaxial compression (UCS) tests, failure mode observation, and SEM. The results show that increasing C/T and concentration markedly enhances compressive strength: the maximum 28-day UCS reached 5.38 MPa under unclassified tailings, C/T = 1:4, 70%. Moreover, unclassified tailings exhibited a later-age strength gain of 244.9%, far exceeding the 58.5% observed for classified tailings. Failure modes evolve from brittle splitting to shear-dominated behavior as mixes densify, reflecting a transition from near-symmetric early-age stress/microstructural fields to asymmetric localized failure (symmetry breaking). SEM reveals that higher binder ratios and concentrations promote C-(A)-S-H-dominated gel formation, improved ITZ continuity, and reduced apparent porosity, thereby restraining microcrack initiation and coalescence. These findings elucidate the micro-to-macro mechanisms governing CTB strength and failure and provide field-relevant guidance for mix optimization and safe, efficient underground backfilling. Full article

Optimal mechanical parameters for successful bone-healing remain unclear despite their critical influence on fracture outcomes, and the timing of post-surgery mobilization is still controversial despite many clinical observations and pre-clinical studies. In this bioreactor in vitro work, we investigate the effect of fundamental parameters such as timing, duration, and frequency of mechanical stimulation on the endochondral bone-healing paths, specifically on the hypertrophic chondrocyte differentiation of naïve human mesenchymal stromal cells (hMSCs). Human MSCs encapsulated in Gelatin-Methacryloyl hydrogels (GelMa) were subjected to three different 10% strain protocols: P1 (168 long-break cycles spread over 14 days), P2ce (cycle equivalent: 168 short-break cycles condensed in 42-min stimulation followed by 14 days free swelling), and P2te (time equivalent—14 days continuous stimulation, 80′640 short-break cycles). In the free-swelling control group, samples were cultured for 14 days without any mechanical stimulation. Our results confirmed that 10% strain induces a robust hypertrophic chondrocyte differentiation of naïve MSCs in all three tested protocols, as demonstrated by enlarged cell size, rounded morphology, robust upregulation of hypertrophic markers (COL10A1, MMP13, RUNX2, ALP), and reduced glycosaminoglycan production. Of particular interest, we show that P2ce (early short stimulation) was as effective as the two extended stimulation protocols, suggesting that initial mechanical signals are sufficient to trigger cell differentiation toward a hypertrophic chondrocyte phenotype that continues even after stimulation ceases. These in vitro findings provide crucial insights into the cellular basis of endochondral ossification during the early phase of loading and show a beneficial long-term effect of early mechanical stimulation. By demonstrating that the cellular mechanobiology of hypertrophic differentiation responds to brief early stimulation, our findings provide a scientific foundation to guide future in vivo investigations on how rehabilitation protocols could influence fracture healing. Full article

To address the shortcomings of traditional polyurethane (PU) sealants, including inadequate weather resistance, low curing efficiency, and limited environmental performance, this study synthesized a functional silicone oligomer (DQPSi) featuring both dynamic crosslinking and hydrophobic properties via the sol–gel method, which was subsequently incorporated into the polyurethane matrix. The effects of DQPSi content (0–20 wt%) on the properties of silane-modified polyurethane (SPU) sealants were systematically investigated. Results demonstrate that DQPSi significantly enhances the comprehensive performance of the material. At 15% loading, the sealant achieves optimal performance balance: surface-drying time shortens to 110 min (45% reduction), curing rate increases to 1.7 mm/d (112.5% improvement), tensile modulus rises by 14% to 0.88 MPa, elongation at break substantially increases to 420%, and contact angle improves to 78° with markedly enhanced hydrophobicity. Microscopic analyses (SEM, nanoindentation) confirm that these improvements stem from DQPSi forming a uniform interpenetrating network (IPN) structure with the PU matrix, where dynamic Si-O-Si bonds provide rigidity and stress dissipation while hydrophobic groups (methylpropyl) migrate to the surface to form a barrier. However, excessive addition (20%) induces silicone phase separation and over-crosslinking, causing mechanical degradation (tensile strength decreases to 0.70 MPa, elongation at break drops to 331%) and microcrack formation. This research elucidates DQPSi’s reinforcement mechanism and critical loading threshold, establishing theoretical and technical foundations for developing high-performance eco-friendly silane-modified polyurethane sealants. Full article

The aim of this study was to produce and characterize bioplastics derived from sweet potato peel starch, Aloe vera gel, and eucalyptus essential oil. Starch from sweet potato peels was extracted using a wet method, yielding 3.54%, while eucalyptus oil was obtained via steam distillation, with a yield of 1.4%. In order to assess the influence of Aloe vera and eucalyptus oil concentrations on the properties of bioplastics, a 2^2 factorial design was implemented. Consequently, bioplastic films were produced using the casting technique. As a result, the films appeared brown, translucent, and homogeneous, while also exhibiting a rough surface texture. Mechanical testing revealed that the films possessed a high Young’s modulus of 41.1 ± 11.1 MPa, a maximum tensile strength of 2.1 ± 0.4 MPa, and an elongation at break of 21.6 ± 4.3%. These properties were achieved with a formulation containing 70% w/w Aloe vera, 0.6% w/w eucalyptus oil, and 5% w/w sweet potato peel starch, suggesting a promising eco-friendly alternative to conventional plastics for potential use in packaging applications. Full article

High-performance spun bionanocomposite fibers, composed of high-molecular-weight chitosan (HMW), low-molecular-weight chitosan “oligomers” (LMW), and cellulose nanofibers (CNFs), were successfully fabricated via gel spinning of viscous aqueous chitosan (CHI) based formulations into a NaOH coagulation bath. The X-ray diffraction (XRD) analysis revealed that the incorporation of cellulose nanofibers contributed to enhance crystallinity of chitosan in spun fibers. The spinning process, which comprised sequential acidic solubilization, basic neutralization, stretching, and drying steps, produced chitosan/CNF composite fibers with high crystallinity, further enhanced by the incorporation of low molecular weight chitosan. The cellulose nanofibers seem to promote CHI crystallization, by acting as nucleation sites for the nucleation and growth of chitosan crystals, with those latter of LMW further enhancing crystallization and orientation due to higher mobility of shorter polymer chains. Two-dimensional XRD patterns demonstrated the preferential alignment of both CNFs and chitosan crystals along the fiber axis. Increasing the proportion of short-chain chitosan led to a reduction of the viscosity of collodion, facilitating the spinning of solutions with higher polymer concentrations. The X-ray diffraction (XRD) analysis revealed that the addition of low-molecular-weight chitosan (LMW), with an intermediate molecular weight Mw of ~4.4 × 10⁴ g/mol, produced the most significant improvements in the crystallinity index (CrI) and orientation. This structural enhancement corresponded to superior mechanical properties like Young’s modulus, yield stress σ_y, and stress-at-break σ_b of the processed composite fibers. By incorporating that intermediate molecular weight chitosan, a Young’s modulus as high as 20 GPa was achieved for the spun composite fibers, which was twice higher than the modulus of around 10 GPa obtained by adding the lowest molecular weight chitosan of Mw ~ 2.9 × 10⁴ g/mol in the composite, and largely above the modulus of around 5 GPa obtained for fiber just spun with chitosan without incorporation of cellulose nanofibers. Full article

A series of PTT-b-PTMG copolyesters was synthesized via direct esterification followed by melt polycondensation using purified terephthalic acid (PTA), bio-based 1,3-propanediol (PDO), and poly(tetramethylene glycol) (PTMG) of varying molecular weights (650–3000 g/mol). The resulting materials were comprehensively characterized in terms of chemical structure, molecular weight, thermal behavior, phase morphology, crystalline architecture, and mechanical performance using a range of analytical techniques: Fourier-transform infrared spectroscopy (FTIR), ¹H-NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), dynamic mechanical thermal analysis (DMA), tensile testing, and other standard physical methods. FTIR, ¹H-NMR, and GPC data confirmed the successful incorporation of both PTT-hard and PTMG-soft segments into the copolymer backbone. As the PTMG molecular weight increased, the average sequence length of the PTT-hard segments (L_n,T) also increased, leading to higher melting (T_m) and crystallization (T_c) temperatures, albeit with a slight reduction in overall crystallinity. DMA results indicated enhanced microphase separation between hard and soft domains with increasing PTMG molecular weight. WAXS and SAXS analyses further revealed that the crystalline structure and long-range ordering were strongly dependent on the copolymer composition and block architecture. Mechanical testing showed that tensile strength at break remained relatively constant across the series, while Young’s modulus increased significantly with higher PTMG molecular weight—concurrently accompanied by a decrease in elongation at break. Furthermore, the elastic deformability and recovery behavior of PTT-b-PTMG block copolymers were evaluated through cyclic tensile testing. TGA confirmed that all copolyesters exhibited excellent thermal stability. This study demonstrates that the physical and mechanical properties of bio-based PTT-b-PTMG elastomers can be effectively tailored by adjusting the molecular weight of the PTMG-soft segment, offering valuable insights for the rational design of sustainable thermoplastic elastomers with tunable performance. Full article